Keywords: Parallel Mechanisms, Modeling and Design of Mechatonic Systems, Compuational Models and Methods
Abstract: A cable-driven parallel manipulator (CDPM) is driven by a set of cables instead of rigid links. Since cables have more flexibility than rigid links, stiffness of a CDPM has been a concern for applications requiring controllable system stiffness. This paper studies the effect of cable tensions on the stiffness of a CDPM that has six degrees of freedom and are driven by seven cables. Both upper and lower limits of the tension in a cable are taken into account in order to mimic real-world scenarios. The natural frequencies of the CDPM at all poses in the workspace are calculated based on interval analysis. Simulation results show that increasing antagonistic cable tensions does not necessarily increase the stiffness of the CDPM within a certain set of poses. The stiffness of a CDPM does not necessarily monotonically increase or decrease with the increase of antagonistic cable tensions. Moreover, a larger change of antagonistic cable tensions does not always lead to a larger change in the stiffness of the CDPM for a certain set of poses. Both cable tensions and the current pose contribute to the stiffness of the CDPM. The effect of cable tensions on the stiffness of a CDPM discussed in this paper provides a guideline to select the set of poses in order to control the stiffness of a CDPM via adjusting cable tensions.

Keywords: Parallel Mechanisms, Design Optimization in Mechatronics, Modeling and Design of Mechatonic Systems
Abstract: Isotropy analysis of workspace plays a critical role in improving the quality of workspace for parallel manipulators. Although various workspace determination approaches have been studied intensively for parallel manipulators in the past decades, workspace isotropy analysis for parallel manipulators has been seldom touched. This paper proposes two novel workspace geometric shape isotropy indices, namely, translational workspace isotropy index and entire workspace isotropy index, for workspace analysis of planar parallel manipulators. Both indices are mathematically defined and can be used to evaluate the isotropy of the geometric shape of the workspace. They are good indicators of the robustness of a planar parallel manipulator to external planar rotational disturbances to the base and can be used as a guideline for optimal design of planar parallel manipulators. Both indices proposed in this paper are evaluated in the optimal design of an example planar cable-driven planar parallel manipulator through simulation.

Keywords: Parallel Mechanisms, Design Optimization in Mechatronics, Flexible Manipulators and Structures
Abstract: This paper introduces a parametric design of a new 3D compliant parallel manipulator based on pantograph linkage for micro/nano applications. Furthermore, the modal shapes and natural frequencies analysis are carried out versus the flexure joint parameters which are a crucial point for the controller selection/design and geometry optimization. The new compliant manipulator provides decoupled 3DOF translational motion with fixed orientation of the end effector and it has significantly high workspace to size ratio. The modified manipulator aims to enlarge the workspace by enhancing the values of magnification factors of input motion and by reducing the parasitic motion and geometric stiffening of the original manipulator. The main parameters that affect the performance of the compliant manipulator are determined based on the generated results of finite element analysis which is performed using ANSYS software. The results have successfully demonstrated the improvements of the proposed manipulator in terms of workspace size, magnification factors, joint stiffening and parasitic motions.

Keywords: Design Optimization in Mechatronics, Legged Robots, Parallel Mechanisms
Abstract: In this paper, we propose an energy-efficient robotic leg design using a redundantly actuated parallel mechanism (RAPM). By adding an actuator parallel to the seriallyactuated leg, we show that the legged machine can reduce mechanical energy loss. We begin with reviewing kinematic model of parallel mechanisms and then present an optimal torque distribution algorithm among redundant actuators which minimizes antagonistic power, a measure for mechanical energy loss due to power conflict in actuators. As an example study, given end-effector (foot) force and motion profile generated by the spring-loaded-inverted-pendulum (SLIP) running, we demonstrate how much the antagonistic power can be reduced by applying the proposed leg design and optimization algorithm in simulation. Also, it is presented that the choice of actuated joints in parallel mechanism affects the performance (energy efficiency). Finally, we demonstrate that the proposed design is also effective in walking, which validates the hypothesis that the proposed RAPM leg design can be effective in a range of locomotion tasks.

Keywords: Parallel Mechanisms, Modeling and Design of Mechatonic Systems, Actuators in Mechatronic Systems
Abstract: This paper presents a novel design of an integrated electro-magnets driven spherical parallel manipulator which produces 3-degree-of-freedom (3-DOF) rotational motion within the workspace. The spherical parallel manipulator is actuated by the interaction between stator coils and the rotor magnetic field. The kinematic and dynamic models are developed. The torque model is formulated analytically based on the magnetic field distribution of the permanent magnet slide unit. Finally, the magnetic field distribution and the torque model are both validated using the finite element analysis.

Keywords: Modeling and Design of Mechatonic Systems, Parallel Mechanisms, Humanoid Robots
Abstract: This paper describes the conception, design, fabrication and testing of a wrist for a new humanoid robot. The wrist is comprised of a three degrees-of-freedom (DOF) parallel mechanism actuated by three motors. The wrist was made to be lightweight and cost-efficient. The design is optimized to fit within the forearm of the robot and is equipped with joint and calibration sensors. It was then tested for consistency in performance and positioning accuracy.

Keywords: Robot Dynamics and Control, Control Application in Mechatronics, Design Optimization in Mechatronics
Abstract: This paper introduces an extension to a method for fast and close to optimal trajectory generation for articulated robots in the case where dynamic constraints and real-time capability are considered. We aim at solving reaching motion problems without pre-defined timing requirements, where the robot starts from its current state trying to reach the final desired state. Our approach combines the advantage of Sequential Action Control (SAC) with an indirect optimization process to further improve optimality and not violate final state constraints while still being applicable for online implementation. Simulation results on a 2 degree of freedom (DOF) and a 3 DOF KUKA-based platform are evaluated to show the improvement of our method in comparison to SAC and other optimal control methods in terms of cost efficiency and computation time.

Keywords: Mobile Robots, Sensors and Sensing Systems, Sensor Integration, Data Fusion
Abstract: This paper presents laser-based tracking (estimation of pose and size) of moving objects using multiple mobile robots as sensor nodes in Global navigation satellite system (GNSS)-denied environments. Each sensor node is equipped with a multilayer laser scanner and detects moving objects, such as people, cars, and bicycles, in its own laser-scanned images by applying an occupancy-grid-based method. It then sends measurement information related to the moving objects to a central server. The central server estimates the objects’ poses (positions and velocities) and sizes using Bayesian filter. In this cooperative-tracking method, the nearby sensor nodes always share their tracking information, allowing tracking of invisible or partially visible objects. To perform reliable cooperative tracking, sensor nodes should accurately identify their relative pose. In GNSS-denied environments, the relative pose is estimated by scan matching using laser measurements captured by nearby sensor nodes. Such cooperative scan matching is performed by 4-points congruent sets (4PCS) matching method for coarse registration and Iterative closest point (ICP) method for fine registration. The experimental results of tracking a car, a motorcycle, and a pedestrian with two sensor nodes in an outdoor GNSS-denied environment validate the proposed method.

Keywords: Planning and Navigation, Fixture and Grasping, Humanoid Robots
Abstract: This paper identifies high-performing Open Motion Planning Library (OMPL) planners for grasp execution and simultaneously presents useful benchmark data. Four grasp executions were defined using a UR5 manipulator. The performance was measured by means of solved runs, computing time and path length. Based on the results, planners are recommended and the reasons are discussed.

Keywords: Planning and Navigation, Compuational Models and Methods, Service Robots
Abstract: Dynamic roadmaps (DRM) are a planning approach for robots in changing environments where fast replanning is required. DRMs are based on a precomputed graph in the configuration space and mappings from workspace voxels to vertices and edges in the graph, which allows for computation times below 100~ms. While dynamic roadmaps can in principle be applied to dual-arm motion planning, it may be beneficial to use independent roadmaps per arm. This paper proposes four different approaches for planning based on two separate DRMs that all take advantage of the availability of workspace mappings. A sequential approach first plans for a prioritized arm and then considers its motion as obstacle for the second arm. The other three planners coordinate the motion of the arms along fixed paths or graphs such that no collision occurs. Benchmarks are performed for two robot models with different ratios of overlapping workspace to investigate the pros and cons of the composition approaches and to compare them to a single roadmap for the dual-arm robot.

Keywords: Service Robots, Modeling and Design of Mechatonic Systems, Machine Vision
Abstract: Trajectory planning has been a common and important topic in robotics since its generation. As a powerful tool, it can enhance the performance of the robots in manufacturing industry. In this paper, a trajectory planning method based on unit quaternion was proposed. Unit quaternions were used to represent the orientations of the target as there are no more singularities. The trajectory was planning in Cartesian space using Paul’s method and the orientations were intermediated using spherical linear interpolation. Experiments on PUMA 560, the analytical inverse kinematics solutions were figured out to generate the joint trajectory for the execution phase. A virtual simulation platform was built up to verify and illustrate the trajectory planning algorithm. The data of target can be updated with time which is meaningful to the visual servo system.

Keywords: Mobile Robots, Planning and Navigation, Service Robots
Abstract: This paper addresses the safe and legible navigation of mobile robots in multi-agent encounters. A novel motion model provides the basis to predict, plan and coordinate agent trajectories in intersection scenarios. The approach establishes an implicit, non-overt cooperation between the robot and humans by linking the prediction and planning of agent trajectories within a unified representation in terms of timed elastic bands. The planning process maintains multiple topological alternatives to resolve the encounter in a manner compliant with the implicit rules and objectives of human proxemics. The trajectory is obtained by optimizing the timed elastic band considering multiple conflicting objectives such as fastest path and minimal spatial separation among agents but also global proxemic aspects such as motion coherence within a group. Cooperation is achieved by coupling predicted and planned agent trajectories to eventually reach an implicit agreement of the agents on how to circumnavigate each other. The parameters of the cost functions of the underlying motion model are identified by inverse optimal control from a dataset of 73 recorded encounters with up to five humans and a total of 283 individual trajectories. Playback simulations of recorded encounters and experiments with a robot traversing a group of oncoming humans demonstrate the feasibility of the approach to resolve general proxemic encounters.

Keywords: Biomechatronics, Space Robotics
Abstract: We have developed an excavation robot for lunar-subsurface exploration. This robot moves using a mechanism based on the peristaltic crawling of earthworms, which can move stably. In our previous study, we demonstrated that the robot can excavate down to 938 mm using this technique. However, it can only excavate in a straight configuration. If it can excavate while curving, its exploration range would expand. Therefore, in this paper, we develop a curving-excavation method for this robot. Firstly, this method is proposed and developed. Secondly, we design the propulsion units necessary to realize this method. Finally, we conduct experiments to confirm curving motion using a robot equipped with the designed unit and evaluate the performance of this method.

Keywords: Biomechatronics
Abstract: In recent years, ventilation equipment has been installed in various structures to draw in outdoor air and circulate indoor air. These ventilation installations have pipes (ducts) through which air flows. If dust accumulates in a duct, it will be carried indoors by the airflow. Dust adversely affects human health, and so these ducts must be cleaned regularly. However, the existing cleaning methods are inadequate for the Ducts having small diameter and many curved points, that are used in houses. Thus, to clean such ducts, we have developed a robot that moves imitating peristaltic crawling. This motion is suitable for moving in ducts because it is stable in curved and narrow pipes. In addition, the robot can move and clean the duct at the same time because it moves forward by holding the pipe walls. In this paper, we outline the development of such a robot. From the results of using the robot to clean the inside of duct, we find a cleaning performance of it.

Keywords: Humanoid Robots, Legged Robots, Mobile Robots
Abstract: This paper proposes a biomechanical analysis of human locomotion to define a reference system for designing flexible-wheeled biped robots. The novelties proposed with this paper are twofold: 1) to revolutionize the concept to design humanoid robots as a complete imitation of humans; 2) to reduce the gap between humans and humanoids designing systems obtained by studying limits of human abilities instead of optimizing humanoid capabilities. In this first study, a human walking model is designed with some added constraints. In particular, the feet are always in contact with the ground. Results of this work are used to optimize the real flexible-wheeled biped robot, named ROLLO, with the final aim to move the robot like a human but bypassing the complexities of the human body and the robotic control.

Keywords: Biomechatronics, Sensors and Sensing Systems
Abstract: In recent years, road collapse accidents due to leakage of aging sewage pipes have become a major social problem. To prevent accidents, the inside of the sewage pipe must be inspected. However, it is difficult to inspect long-distance pipes with diameters of 100 mm or less and curved pipes. Therefore, in this research, we develop an inspection system that uses earthworm movement which can drive steadily over long distances even in narrow spaces. This research involves traveling experiments on straight horizontal pipes, straight vertical pipes, and 90° pipes, and the usefulness of the proposed approach is confirmed. In this report, we present the device to estimate the shape of sewer pipelines and confirm its usefulness by experiment.

Keywords: Mobile Robots, Vehicle Technology
Abstract: The vehicle using omnidirectional wheels has ability to move in all directions without changing the body direction unlike a normal four wheel drive vehicle. However most of omnidirectional vehicle are designed for using only on flat ground. In this paper, we propose a new type of omnidirectional wheel, “Spiral Mecanum Wheel”, which enables vehicle climb the step. This new wheel consists of spiral beams and many small rollers, and these small rollers are arranged along the spiral beams. When the vehicle with this spiral Mecanum Wheels moves in normal direction, the edge of the spiral moves to cover the step from above. We have performed the experiments using Spiral Mecanum Wheel and showing the wheel works very well. As a result, in the experiment using single Spiral Mecanum Wheel, this Spiral Mecanum Wheel climbed the step about 83% of the wheel diameter in normal direction motion. The vehicle with Spiral Mecnaum Wheel climbed the step about 37% of the wheel diameter in tangential direction motion and 59% in normal direction.

Keywords: Mobile Robots, Modeling and Design of Mechatonic Systems, Robot Dynamics and Control
Abstract: In this study, the motion of an inverted pendulum mobile platform is extended to omnidirectional motion. omnidirectional motion is implemented by a drive unit constructed from paired mecanum wheels. The mechanism of the omnidirectional drive unit replaces the two parallel wheels of the inverted pendulum mobile platform and extends its motion to an omnidirectional motion. The mechanism of the omnidirectional drive unit and the control system are described. The control system is also extended to integrate the additional lateral motion into the two-parallel-wheel-type inverted pendulum control and performs path following control of the in-plane motion with complete three degrees of freedom. A simple additional control method is presented for the trajectory following control of the system that has unstable degrees of freedom. The ability of the system is demonstrated through an experiment of a trajectory following task. The experimental results indicate the omnidirectional motion ability of the mobile platform with auto balance and demonstrate the appropriate control method.

Keywords: Applications of nano technology, Design/control of MEMS-nano devices
Abstract: Polymerase chain reaction (PCR) is used to amplify small amount of Deoxyribonucleic Acid (DNA). ). It has been used extensively in biomedical laboratories and has become a powerful tool for clinical, medical diagnostic, biological, forensic and genetic analysis and other areas of life science. This process actively increases the amount of DNA by repetition of three step procedure which includes denaturation, annealing and extension, which are to be performed at 95oC, 72oC and 55oC respectively. These temperatures are maintained by attaching the heaters in the denaturation, extension and annealing zones of PCR device. In the proposed design the PCR channel is embedded in a glass substrate which is a solid domain and conduction being the dominant heat transfer phenomena in a device. Heat flows from high temperature region to low temperature region during conduction, making it difficult to maintain the constant temperature zones in the solid domain which is a necessary requirement to avoid thermal cross talk between the zones. Multiple methods are proposed in the literature for this purpose. They include use of insulation materials, creation of air gaps between the three zones, and the use of two heater configurations with cooling jackets to maintain constant temperature in the middle zone. In this work, three-dimensional heat transfer plus computational fluid dynamics (CFD) simulations are performed to study the temperature distribution and heat transfer characteristics in a continuous flow glass based PCR device using three and one heater configurations. Three heaters of constant temperature are attached to the lower surface of the glass substrate and a comparison of temperature distribution along lateral direction is carried out for 8mm and 9mm heater lengths. Then one heater configuration is used in such a way that there is a thin sheet made of invar and is placed between the heater and the PCR device. The temperatures in the zones without heaters are controlled by fluid convection phenomena. The comparison of residence time for both configurations shows that the residence time is independent of number of heaters and the temperature distribution in a PCR channel. The study provides a useful comparison between

Keywords: Robot Dynamics and Control, Legged Robots, Micro-Electro-Mechanical Systems
Abstract: This paper examines the dynamics of a type of millimeter-scale hexapod microrobot based on piezoelectric actuation. These robots, having a 5mm x 2 mm footprint, are formed from integrated thin-film lead zirconate titanate (PZT) and high-aspect-ratio parylene-C polymer structures. The in-chip dynamics of the microrobots are measured when actuated with tethered electrical signal, to demonstrate the resonant behavior of different parts of the robot. Out-of-chip robot motion is then actuated by external vibration after the robot has been detached from its silicon tethers to external power. A dynamic model for robot and ground interaction is presented and validated to explain robot locomotion in the vibrating field using the in-chip measurements of actuator dynamics and certain additional design information. The model accounts for the interaction between the robot and ground, for multiple resonances of the robot leg, and for rigid robot body motion in 3 degrees of freedom. The dynamic model with first vertical and lateral resonant modes of leg shows a good match with experimental results for the motion of the robot on a vibrating surface actuated within low-frequency range.

Keywords: Design/control of MEMS-nano devices, Actuators, Opto-Mechatronic Sensors
Abstract: High resolution and high throughput imaging are typically mutually exclusive. While there is a wide range of techniques to image features beyond the diffraction limit of light, they all have their own benefits and drawbacks, but they are often very slow compared to optical systems. As such, extending the performance of optical microscopes remains. Examples of high resolution optical concepts are metamaterials nano-antennas, superoscillatory lenses and hyperlenses. These concepts require precise and high speed positioning of the optical element at lens-to-sample separations measured in tens of nanometers. We present a design and process for a MEMS nanopositioning stage capable of sub-nm positioning of a metamaterials optical lens with very high bandwidth. Laser vibrometer measurements on the first batch of fully fabricated devices showed that the first eigenfrequency is at 500±25 kHz, somewhat below the 660 kHz obtained by FEM simulations. Due to squeeze film damping, the quality factor is relatively low (approximately 2-2.5), which is advantageous for reaching high positioning bandwidth when the device is used in a near-field optical imaging microscope.

Keywords: Micro-Electro-Mechanical Systems, Actuators, Design/control of MEMS-nano devices
Abstract: Advanced microscopy techniques can permit imaging beneath the tissue surface in hollow organs where cancer can begin. This work examines the design, modeling, fabrication and control process for an electromagnetic z-displacement, or into-tissue, scanning microactuator based on semiconductor fabrication methods. Dynamic modeling and control of the microactuator allows it to perform large vertical displacements despite nonlinearities of thick-film magnetic material behavior and closely-spaced dynamic modes from the compliant actuator structures. Nearly single frequency oscillation of >100 µm vertical displacement at 15 V is achieved by implementing an open-loop input linearization control tsignal. Nearly pure vertical motion of the microstage prevents the focal point of actuator lens from deviating from an axial laser path, necessary to capture images with high resolution.

Keywords: Design/control of MEMS-nano devices, Flexible Manipulators and Structures
Abstract: This paper presents the mechanical design of a novel 3-PSS (P and S represent the prismatic and spherical joints, respectively) parallel-kinematic flexure nanopositioning stage. This stage provides a high-precision motion driven by three piezoelectric actuators. By employing the compound displacement amplifier and 3-PSS parallel mechanism, the flexure nanopositioning stage can deliver two rotational degree-of-freedom (DOF) and one translational DOF. Statics modeling and dynamics analysis of the nanopositioning stage are carried out to evaluate the performance of the stage. To verify the accuracy of the analytical modeling, simulation studies with finite element analysis (FEA) are carried out. Results demonstrate the promising performance of the designed spatial nanopositioning stage for dexterous micromanipulation applications.

Keywords: Tele-operation, Micro-Electro-Mechanical Systems, Sensors and Sensing Systems
Abstract: This paper presents a method to improve the robustness of the position control of a small permanent magnet within a living organism, such as the human body in micro-surgery. So far, position control has been achieved up to 5 Degrees of Freedom with robustness against predicted and modeled disturbance. In order to achieve robust control against non predicted disturbances, the use of a disturbance observer was proved efficient in the past. Disturbance observers require fast and accurate position sensing, which has been achieved so far by optical position sensing. In an effort to extend the operational range of magnetic levitation systems, this paper also considers the use of a position sensor which does not rely on optical sensors, but inductance variation. The models for simulations are based on the Octomag system, which is one of the most up-to-date magnetic levitation devices.

Keywords: Control Application in Mechatronics, Novel Industry Applications of Mechatroinics, Mechatronics in Manufacturing Processes
Abstract: Recently, in the manufacturing process of flat panel displays, mass production method of the in-line system has been emerged. In particular, the next generation OLED display manufacturing process, horizontal in-line evaporation process has been tried. It is important for the success of OLED inline evaporation process to develop a magnetic levitation transport system capable of transferring a carrier equipped with a mother glass with high accuracy without any physical contact along the rail under vacuum condition. In the case of existing wheel-based transfer system, it is not suitable for OLED evaporation process requiring high cleanliness. On the other hand, the magnetic levitation transport system has an advantage that it does not generate any dust and it is possible to achieve high-precision control because there are not non-linear factors such as friction force. In this paper, we introduce the high accuracy magnetic levitation transport system for OLED evaporation process currently under development and design of levitation controller using cascade control consisting of current control (PI) and airgap control (PID).

Keywords: Modeling and Design of Mechatonic Systems, Actuators in Mechatronic Systems, Design Optimization in Mechatronics
Abstract: This paper presents the integrated design of a magnetically levitated dual-stage positioning system to improve the bandwidth of traditional maglev positioning systems. The primary stage of the proposed dual-stage system is a 6 DOF maglev positioning system, and a specifically designed flexure-based actuator is utilized as the secondary stage to further compensate the error of primary stage. Compared with the primary maglev stage, the flexure-based secondary stage owns the advantages such as high stiness, high nature frequency, and non-commutation. The plant and controller parameters of the secondary stage is integrally designed in this work, where various control/mechanical specifications are considered and formulated as the constraints in an optimization problem. The prototype of designed secondary stage is fabricated, and the experiments indicate that the bandwidth of the flexure-based secondary stage is largely improved compared with the primary maglev stage.

Keywords: Novel Industry Applications of Mechatroinics, Actuators in Mechatronic Systems
Abstract: Torque limiters are a proven way to enhance the safety in robots. To further increase the safety, adjustable torque limits depending on the task and the joint configuration (joint angles, velocity, acceleration) would be preferable. Friction clutches can be used as adjustable torque limiters (ATL). In contact free motion the ATL can be set with torque limits higher than the required torque, thereby not influencing the position tracking performance. At an impact, the torque is intrinsically limited, enhancing the safety. Furthermore, depending on the implementation, friction clutches have another relevant property. They can have different torque limits for static and kinetic friction: when the static torque limit is exceeded (as it would be the case in an incidental contact situation), the clutch starts slipping, and the torque output automatically decreases, thereby reducing the forces in a quasi-static contact, as defined in ISO/TS 15066:2016. Impact experiments validate the safety benefits outlined above. The current paper implements and profiles an ATL, which exhibits a kinetic torque limit of only 50.4% of the static torque limit at 10rpm. This ensures both an adjustable torque limit fitting to the task requirement and a lower but not zero torque after impact for enhanced safety.

Keywords: Actuators in Mechatronic Systems, Modeling and Design of Mechatonic Systems, Identification and Estimation in Mechatronics
Abstract: Tendon-sheath actuation mechanism has been researched due to its extremely simple and light cable routing structure. However, the slide-based force transmission mechanism causes friction, which disturbs precise force control. To overcome such disadvantage, friction compensation algorithms in tendon-sheath actuation systems have been studied. However, the torque control of double tendon-sheath mechanism has not been achieved yet without a torque feedback. In this research, a double-tendon sheath actuation mechanism with series elastic elements and tight sheath routing method is introduced to achieve feedforward torque control. The performance of proposed mechanism is verified with experiments.

Keywords: Motion Vibration and Noise Control, Learning and Neural Control in Mechatronics
Abstract: For an accurate and precise periodic scanning motion of a galvanometer scanner, this paper presents iterative learning control (ILC) that is designed and implemented in the frequency domain to compensate for system nonlinearities, such as static friction. For a case that system identification in advance is difficult due to the nonlinearities, the frequency-domain ILC itself incorporates and performs system identification during iterative learning, as modeling-free inversion-based iterative control (IIC). A learning law is derived for a nonlinear system, where the internal system identification is formulated as an estimation problem of a Jacobian matrix that represents the system. In order to find a suitable Jacobian estimation method in the IIC, this paper compares Broyden's method and the linear method, as well as the secant method. To decease the algorithms, the IIC is operated only at the harmonic frequencies of the motion trajectory. In the implementation of the modeling-free IIC, the control input update is explicitly separated from the Jacobian estimation, so that the IIC can still decrease the motion error even when the Jacobian estimation is interrupted for stability. The experimental results demonstrate that the secant method is the best of the three for raster scanning due to its fast learning and high tracking performance.

Keywords: Control Application in Mechatronics, Learning and Neural Control in Mechatronics, Robot Dynamics and Control
Abstract: Velocity field control (VFC) is an alternative approach for motion control of robotic systems. It has advantages over the trajectory tacking problem when the timing in the desired task is of less importance in the application of interest. Recently, this control strategy has been emerged as a promising control method in robot-aided rehabilitation. Therefore, this paper addresses the problem of VFC for robotic exoskeletons with dynamic uncertainties. Most existing VFC methods require some knowledge of the dynamic model of the robot, which is usually difficult in practice to precisely identify. Consequently, this paper design an adaptive neural network VFC method to compensate for the dynamic uncertainties. The controller gives a priori bounded control command in order to take into account the saturation of actuators. The controller performance is validated through simulation and experimental studies on a two-degree-of-freedom lower-limb robotic exoskeleton.

Keywords: Machine Learning, Neural Networks, Artificial Intelligence in Mechatronics
Abstract: In this work a novel approach to Transfer Learning for the use in Deep Reinforcement Learning is introduced. The agent is realized as an actor-critic framework, namely the textit{Deep Deterministic Policy Gradient} algorithm. The Q-function and the policy are represented as deep feed-forward networks, that are trained by minimizing the mean squared Bellman error and by maximizing the expected reward, respectively. For Transfer Learning, the actor is modified with a new regularization term, called the textit{knowledge regularizer}. It allows to include prior knowledge in from of an existing policy in the learning process. The textit{knowledge regularizer} shifts the current weight vector during the gradient descent step towards a region of the weight space, that is centered around the existing policy. Because neural networks are universal and smooth function approximators, the weights of the existing policy and the new ones have to lie close to each other in the weight space. Solving a task therefore benefits from the prior knowledge, when it is used to manipulate the gradient given by the critic. We could experimentally verify, that the textit{knowledge regularizer} results in a higher performance achieved by the agent and in a reduction of the learning time. Furthermore, the textit{knowledge regularizer} can be used as a replacement for labeled training data, which renders it especially useful for physical applications.

Keywords: Control Application in Mechatronics, Automotive Systems, Modeling and Design of Mechatonic Systems
Abstract: In this work an estimation based iterative learning control (ILC) approach for a vehicle suspension rig is presented. Slow convergence rates and non-monotonic learning transients of the typically cross-coupled multi-axial system require a high number of system measurements. This significantly damages the specimen before the actual endurance test. In combination with inverse model ILC the presented method uses estimates of the test system outputs in a second iteration domain in addition to real system measurements. The method is tested in an experiment and compared to the conventional inverse model ILC approach. The results show a significant reduction of necessary system measurements without non-monotonic learning transients compared to the conventional ILC method.

Keywords: Control Application in Mechatronics, Learning and Neural Control in Mechatronics, Motion Vibration and Noise Control
Abstract: This paper examines an application of the iterative learning control (ILC) scheme for fast and precise positioning of galvano scanners with a combination of short and long interval times. The ILC scheme is well-known as one of the effective control approaches for high-precision motion control of mechatronic systems, and a variety of ILC methods have been proposed in the former literature. Most of the ILC methods are applied to fixed repetitive motions and perform the learning process to compensate effects of model errors, disturbances, and uncertainties. However, the galvano scanners often require sequential repetitive short interval motions between long interval positioning trials for the laser processing, which means that the learning interval time varies between the short and long interval trials. In such special positioning motions, ILC cannot compensate undesired responses sufficiently. In this study, we consider the ILC property for a sequential repetitive movement combining short and long interval motions by theoretical examinations and numerical simulations, and subject matters to be solved are clarified as an initial consideration.

Keywords: Actuators in Mechatronic Systems, Modeling and Design of Mechatonic Systems, Neural and Fuzzy Control in Mechatronics
Abstract: An effective way for the testing of a large number of systems is using single and multi-axis shaking tables. Among the possible applications, the civil engineering field stands out for the testing of structures, or part of them, to high natural dynamic forces. However, due to nonlinearities and structured and unstructured uncertainties of the hydraulic systems, the acceleration signal of these systems with respect to sine input are distorted. This paper is focused on identification of a gray-box acceleration model of a uni-axial servo hydraulic shaking table with respect to sine input signal with different frequencies and amplitude. First, a full system model of servo hydraulic system is developed based on fluid mechanical expressions and steady state friction. Second, for each input frequencies the unknown parameters of the friction, bulk modulus and leakage of the system are identified based on nonlinear least square method. Then, the identified parameters are used to develop a dynamic feed forward neural network model. The gray-box model uses online short fast Fourier transform harmonic identification method to identify the harmonic and amplitude of input signal and the neural network model produces parameters of the system. Finally, the comparison between the experimental results of the acceleration signal and the simulation one demonstrates the accuracy of the model.

Keywords: Mobile Robots, Robot Dynamics and Control, Planning and Navigation
Abstract: This paper investigates a novel approach for transporting an elastic plate using a group of small swarm mobile robots. A formation of omnidirectional mobile robots transports a plate through an unknown environment purely by normal and friction forces between the robots and the plate. The scheme includes the calculation of normal forces by solving a linear complementary problem and the formation control of swarm robot while they keep the stability of the plate. An improved artificial potential field method is used for path planning and formation control of the mobile robots. The robots are controlled fully distributedly and the proposed scheme is carefully and successfully tested in various simulations posing rather sophisticated challenges both to its navigation and formation control subaspects.

Keywords: Network Robotics, Hybrid intelligent systems
Abstract: Swarm Robotics (SR) is expected to have a significant impact on society over the next decade. One of the contributing factors is that swarms are robust. However, robustness has not gained sufficient attention in the context of robotic swarms. This study focuses on the swarm network to generate insights as to how network topologies can be controlled to improve the robustness of SR systems. More specifically, how removing key robots alters the network topology, thereby changing the performance of the swarm. Analyzing these changes provides possible guidelines to improve swarm robustness towards targeted interventions. The most important findings suggest that robustness can be increased by making the network topology: (1) provincial and decentralized in the middle phase of the swarming procedure in unimodal domains, (2) provincial and centralized during the same phase in multi-objective domains.

Keywords: Motion Vibration and Noise Control, Network Robotics, Identification and Estimation in Mechatronics
Abstract: This paper considers the robust cooperative output regulation problem for a class of linear uncertain multi-agent systems. It is assumed that the agents in the system can only access incomplete measurements of the exosystem, and the local regulated error signals are not available to the agents to be used in control. Under these assumptions, the agents in the system cannot independently reconstruct the exosystem dynamics, or rely on their own local measurements to achieve the objectives of the output regulation problem. The solution to the regulation problem proposed in this paper is a distributed dynamic control law that reconstructs the exosystem states, given a mild collective detectability assumption. Furthermore, the proposed distributed control law incorporates an internal model of the exosystem to allow for uncertain dynamics of the multi-agent system. A numerical example is offered to illustrate the effectiveness of the proposed control solution.

Keywords: Mobile Robots, Modeling and Design of Mechatonic Systems, Software Design for System Integration
Abstract: We are designing an unmanned ground vehicle (UGV) for use in a large-scale and long-term environmental monitoring system. Existing high-performance UGVs cannot cope with unexpected events because their design concept, like that of almost all previous mobile robots, is based on the development of a single high-performance robot capable of performing every task. To overcome this limitation, we propose using multiple inexpensive robots and operating them such that each compensates for the shortcomings of the others. The objective of this study is to design a robot that could be used to realize a multiple autonomous mobile robot system for long-term outdoor operation. These robots use only two motors for movement and rely on internal sensors for the control of the robot, thus minimizing the cost. The developed robot is capable of handling unexpected events such that could traverse extreme environments such as forests. The design concept will contribute to the configuration of a multiple robot system and also to increasing the robustness of the overall system. In addition to proposing a robotic system for long-term operation, this study also proposes a novel idea whereby parts of a robot may be sacrificed to attain the overall objective. In this paper, we describe the details of the wheel and the control design of the robot, and also present the results of some experiments using the developed robot.

Keywords: Control Application in Mechatronics, Unmanned Aerial Vehicles, Software Design for System Integration
Abstract: We describe the design and implementation of a Guidance, Navigation and Control (GNC) System for fixed wing Unmanned aerial vehicles (UAVs). This system allows an autonomous navigation by following a desired trajectory defined by a profile of airspeed, altitude and a list of waypoints. The GNC system has a hierarchical architecture and integrates the Controller Area Network data bus, which facilitate the process of implementation and testing. The results of Hardware In the Loop simulations and real-time performances demonstrate the soundness of the implemented system. This article gives the necessary details so the proposed implementation will be reproducible by other searchers.

Keywords: Mobile Robots, Actuators in Mechatronic Systems, Modeling and Design of Mechatonic Systems
Abstract: Bristle-bots are vibration-driven mobile robots characterized by small size, high speed, simple design and low costs for production and application – qualities which are advantageous for agents of swarm robotics. Current studies have focused on their natural behaviour on confined spaces, navigation capabilities through pipes, and mathematical modelling of the bristle-based motion, however, trajectory generation capabilities were not evaluated. Therefore, this paper presents our robot “Donipodis”, a mobile micro-robot for swarm robotics research. Our robot uses a single vibro-motor controlled over an 8-bit microprocessor that generates locomotion using bristles. It possess two IR receivers at its front as antennae and one IR transmitter at its back for peer-to-peer communications, an RGB colour identifier and IrDA communication for master host programming. A modelling of the micro-robot was also developed. Simulations and experimental results show a proper modelling of the locomotion and performance over displacement with slightly curved trajectories. Translation and rotation speeds characterization results show potential for controllable trajectory generation by varying the motor speed properties (PWM frequency and duty cycle) and direction.

Keywords: Planning and Navigation
Abstract: With the increasing complexity of electromagnetic environment and increasing intensity of military confrontation, the potential security exposure in the application of satellite navigation has become one real threat to face. This paper has an analysis on GNSS repeater spoofing technique, for fake Position, fake Time and fake Velocity in theory. The analysis results of this paper will provide beneficial guidance for the development of spoofer. Besides, the spoofing technique and anti-spoofing technique are like lance and shield. The progress on spoofing technique will also promote the development of anti-spoofing technique.

Keywords: Planning and Navigation, Mobile Robots
Abstract: Follow the Gap Method (FGM) is a safety-focused geometric obstacle avoidance algorithm for local navigation. In this method, the largest gap around the robot is selected and the robot moves towards a goal point considering the largest gap and minimum distance to obstacle. One of the drawbacks of the method is the extension of the path which sometimes happens unnecessarily. Another drawback comes from small differences between the gap sizes. This sometimes makes the robot to change the selected gaps instantly which causes zigzag trajectories. In this paper, Improved Follow the Gap Method (FGM-I) is presented to eliminate these two drawbacks. In FGM-I, the gaps are selected according to a new utility function and unnecessary gap changes are penalized. A differential drive powerchair is used in simulations. The simulation results show that the FGM-I reduces the effects of the mentioned problems seriously.

Keywords: Artificial Intelligence in Mechatronics
Abstract: This work is concerned with the robot individuality generation in action control. In the near future autonomous robots will plan and practice actions according to the code of conduct generated by themselves. It is important to investigate how a robot's personality or individual character will form and how to create a desirable one. When only the task objective is given, the control of a complex robot action has a large number of redundant degrees of freedom. The easiness criterion introduced for the arbitrariness resolution in the early stage of optimization affects the optimal action control. From the result of a simple numerical example it is shown that the easiness-based arbitrariness resolution leads to the action control individuality generation.

Keywords: Planning and Navigation, Compuational Models and Methods, Mobile Robots
Abstract: Sampling-based approaches constitute the state-of-the-art for robot motion planning. Collision checking and nearest neighbor search are the major performance bottlenecks of these methods. For an environment with fixed number of obstacles, collision checking for a new candidate state is a constant time operation, whereas nearest neighbor search usually degrades during the runtime of the algorithm. Multiple variants of the single-query probabilistically optimal RRT* algorithm were introduced to tackle these issues. In this work, we present heuristics to augmented RRT* such that it finds the initial solution faster and converges to the optimal solution with less number of nodes. Instead of checking collision for every new node candidate, we consider only samples which are maximum step size away from the nearest neighbor or are near obstacles. With our augmented node concept, we embed nearby obstacle information to the nodes either as a binary variable (RRT*K) or with a higher resolution quadrant based representation (RRT*Q). Extensive benchmark batteries conducted on 2D and 3D problems with geometric constraints show the efficacy of our approach.

Keywords: Planning and Navigation, Mobile Robots
Abstract: This paper introduces a path planning algorithm that takes into consideration different locomotion modes in a wheeled reconfigurable rover. Power consumption and traction are estimated by means of simplified dynamics models for each locomotion mode. In particular, wheel-walking and normal-driving are modeled for a planetary rover prototype. These models are then used to define the cost function of a path planning algorithm based on fast marching. It calculates the optimal path, in terms of power consumption, between two positions, providing the most appropriate locomotion mode to be used at each position. Finally, the path planning algorithm was implemented in V-REP simulation software and a Martian area was used to validate it. Results of this contribution also demonstrate how the use of these locomotion modes would reduce the power consumption for a particular area.

Keywords: Mobile Robots
Abstract: Water, a valuable resource, is usually distributed through urban environments by buried pipes. These pipes are difficult to access for inspection, maintenance and repair. This makes in-pipe robots an appealing technology for inspecting water pipes and localising damage prior to repair from above ground. Accurate localisation of damage is of critical importance because of the costs associated with excavating roads, disrupting traffic and disrupting the water supply. The problem is that pipes tend to be relatively featureless making robot localisation a challenging problem. In this paper we propose a novel simultaneous localisation and mapping (SLAM) algorithm for metal water pipes. The approach we take is to excite pipe vibration with a hydrophone (sound induced vibration), which leads to a map of pipe vibration amplitude over space. We then develop a SLAM algorithm that makes use of this new type of map, where the estimation method is based on the Rao-Blackwellised particle filter (RBPF), termed PipeSLAM. The approach is also suited to SLAM in plastic water pipes using a similar type of map derived from ultrasonic sensing. We successfully demonstrate the feasibility of the approach using a combination of experimental and simulation data.

Keywords: Legged Robots, Walking Machines, Modeling and Design of Mechatonic Systems
Abstract: Passive dynamic walking robot can walk with low energy consumption and exhibits human-like natural gait. However, because the walking performance greatly or fully depends on the mechanical structural parameters, their walking stability is quite low compared to active walking robot. In other words, proper mechanical parameters are one of the key factors to achieve stable walking for a passive dynamic walking robot. In this paper, parametric mechanical structural parameters were used to fulfill the parameters optimization process and optimal mechanical structural parameters were obtained based on the global stability analysis with cell-mapping method by numerical simulation. A passive dynamic biped walking robot prototype with hip joint, knee joints, ankle joints and an upper body was developed based on the optimization result, both the simulation and experiments results proved that the optimization result is reasonable.

Keywords: Humanoid Robots, Walking Machines, Legged Robots
Abstract: Classic biped walking controllers assume a perfectly flat, rigid surface on which the robot walks. While walking over unknown terrain, robots need to sense and estimate the ground location. Errors in this estimation result in an unexpected early or late ground contact of the swing foot. In this paper, we analyze how these errors affect walking stability. Based on simulation results, we propose a strategy that mitigates this effect. We show that if the ground height has an associated uncertainty, an overestimation of its value results in a more stable walk. This overestimation depends on both sensor data and the robot’s dynamics. By using a reduced robot model, our strategy could be implemented into the real-time control to make the robot more robust against perception errors and irregular surfaces.

Keywords: Humanoid Robots, Legged Robots, Robot Dynamics and Control
Abstract: This paper proposes a method to realize sequential-contact bipedal running based on the spring loaded inverted pendulum (SLIP) model. SLIP model has some excellent properties for realizing a natural locomotion, therefore some researchers proposed a method to mimic the SLIP dynamics for multi-body system’s locomotion. In this paper, we propose a method to control contact conditions of a robot model through handling a zero moment point, and we combine it with a method of embedding the SLIP dynamics to multibody system. It makes possible to control both the continuous dynamics and the phase transition of the robot model. Furthermore, to consider other sub tasks simultaneously, we introduce a hierarchical feedback linearization and construct the controller for sequential-contact bipedal running. Finally, we show that the proposed method can produce a desired running through the numerical simulations.

Keywords: Humanoid Robots, Walking Machines, Robot Dynamics and Control
Abstract: In this paper, we present a control method for bipedal robotic walking based on insights we obtain from simple models. Inspired by the virtual pendulum (VP) concept and the spring-mass walking models, we propose a force direction control method to redirect the axial force of a compliant leg in order for walking with upright trunk. We first consider a dynamic simulation of a simple planar walking model to validate the proposed method with proper foot placement rule, under the presence of force disturbance. Finally, we design a controller to implement the proposed force direction control scheme onto a more realistic model, a planar five link biped, which involves individual leg controller and walking state machine. The simulation results indicate that the robot model equipped with the proposed controller can overcome terrains with moderate roughness.

Keywords: Legged Robots, Robot Dynamics and Control, Walking Machines
Abstract: We present balance recovery control of bipedal robotic walkers under foot slip disturbance. A dynamic model is first presented to capture the bipedal locomotion under slip disturbance. Two different control approaches are presented: one is based on the feedback linearization and the second one uses the disturbance observer (DOB) method. The recovery strategies and profiles are designed through linear inverted models and inspired by human walking locomotion profiles. We present and compare the simulation results under both the feedback linearization- and DOB-based control designs.

Keywords: Legged Robots, Service Robots, Flexible Manipulators and Structures
Abstract: In this paper, we introduce a new scanning technique for detecting landmines and unexploded ordnance (UXO). The manipulator arm carried by a hexapod robot is capable of scanning rough terrain using a typical mine detector. To speed up the landmine detection and marking, both scanning and moving forward will be done simultaneously. The controller will perform two tasks. The first task is to keep the sensor-head in a fixed level with respect to the ground and the second task is to keep the base of the arm within a specified range of position and orientation. A coupling between the velocity of the end-effector and the velocity of the manipulator base (robot body) is created to ensure the efficiency of the whole process. To verify the feasibility of our design, three experiments will be performed using simulation in MATLAB. The manipulator was modelled using SolidWorks.

Keywords: Identification and Estimation in Mechatronics, Compuational Models and Methods, Automotive Systems
Abstract: In contemporary mechatronic applications decision-making is often based on information about the underlying model governing the dynamical evolution, in order to ensure optimal operation with respect to a prioritized objective. Modeling errors stemming from parameter uncertainty or varying operational conditions result in inevitable deviations from the theoretical estimate and consequently in suboptimal operation. Intelligent systems need to be equipped with inherent means to compensate for these a priori unknown discrepancies, hereby guaranteeing a robust operation in uncertain environments. In this manuscript, advanced filtering techniques are applied to assess both an optimal model representation and state estimates. An appropriate interconnection between both model and state estimation is determined. The proposed methodology is demonstrated for an electric drive, embodying a DC-source, a voltage source inverter (VSI) and an asynchronous machine, as the presence of discrete switching sequences and physical constraints introduces additional challenges. Results prove that the error on the state estimates can be improved by 92.7-97.2%, outperforming the classical estimation techniques, while the relative model mismatch is scaled down to 0.03%, even in highly demanding scenarios. The introduced strategy thus enables high-fidelity virtual sensing and reliable decision-making procedures for advanced asynchronous drives when modeling errors can be anticipated.

Keywords: Control Application in Mechatronics, Design Optimization in Mechatronics, Software Design for System Integration
Abstract: Brushless DC (BLDC) motors have been widely used in industry. However, one of the main drawbacks of using BLDC motors is the undesirable torque ripple. The torque ripple can cause mechanical vibration, acoustic noise and bearing damage that reduces the lifetime of the machine. This paper proposes a simple repetitive control scheme to attenuate torque ripple of BLDC motors. In this method, the ripple is considered as an undesirable repeated signal that will be minimized by the repetitive control scheme. The control input used in the proposed method is controlled transistors switching using space vector pulse width modulation technique. Simulation results show the proposed repetitive control technique results in the apparent reduction of the torque ripple when compared to a conventional control scheme.

Keywords: Motion Vibration and Noise Control, Actuators in Mechatronic Systems, Vehicle Control
Abstract: The maximum available damping force in electromagnetic dampers has been a bottleneck in their practical utilization. Most of the proposed solutions result in heavy or complicated designs which cannot be used in real-world applications. In this paper, we propose a negative resistance concept which can be created in the damper shunt circuit using a bidirectional boost converter. The negative resistance compensates for some of the internal resistance in the damper circuit and leads to lower overall resistance. As a result, higher currents can be driven in the circuit, and higher damping levels are achieved.

Keywords: Modeling and Design of Mechatonic Systems, Fault Detection and diagnosis in Manufacturing
Abstract: In this paper we present an alternative model of an induction motor that offers the flexibility required for simulation of phase faults scenarios as well as accounting for the effect of leakage saturation in the motor. A non-DQ generalized model is developed and modified to incorporate saturation effect. The performance of the model is evaluated by simulation. The simulation results demonstrate the attainable performance of the model.

Keywords: Motion Vibration and Noise Control, Mechatronics in Manufacturing Processes, Modeling and Design of Mechatonic Systems
Abstract: The use of slender tool holders is inherent to boring and turning operations. As a result, large vibrations, known as chatter, may arise, resulting in poor surface finishing and decrease in the tool life. Therefore, chatter is a recurring issue that is in need of modeling and controlling in order to improve the industry's productivity. The nonlinear and cutting friction forces, together with the mode coupling that arises from a symmetric tool holder, can lead to these extreme vibrations and possibly chaotic motion under a certain set of parameters. These nonlinearities must be studied and experimentally analyzed to be considered in chatter control mechanisms in turning. It is well known that passive shunt circuits increase the system's damping and can be used to control chatter. This paper presents a simple lumped nonlinear model of the tool holder embedded to a piezoelectric patch and an analysis of such model with and without the passive shunt circuit. The set of parameters is chosen in order to simulate a chatter condition. The resulting phase diagrams are qualitatively compared to experimental data obtained from a real turning operation made using a CNC lathe. The results show that the model is capable of appropriately simulating the chatter vibration.

Keywords: Control Application in Mechatronics, Novel Industry Applications of Mechatroinics
Abstract: Increasingly stringent regulations on emission control and energy efficiency operations drive the maritime industry towards hybrid solutions incorporating energy storage and other alternative energy sources into marine power systems. In particular, commercial all-electric hybrid vessels with dynamic operations such as harbor tugs often face significant challenges in power management control to maximize fuel savings, in addition to ensuring power system reliability. An intelligent power management control strategy plays an important role in effectively managing the multiple energy sources and their constraints to achieve desired control objectives. Hence, in this paper, Model Predictive Control (MPC) approach is proposed to address these challenges. The proposed strategy shows comparative performance in terms of fuel savings when compared to the Equivalent Consumption Minimization Strategy (ECMS), with added advantage of improving power system reliability.

Keywords: Modeling and Design of Mechatonic Systems, Actuators in Mechatronic Systems, Control Application in Mechatronics
Abstract: A novel modified Preisach model is proposed to identify and simulate the hysteresis phenomena observed in a piezoelectric stack actuator. Further, an open-loop controller is incorporated to eliminate hysteresis influence. The proposed approach with a continuous, analytical distribution function performs very well when considering the low amount of parameters. In contrast to the classical and discrete Preisach model, this approach can also handle a non-constant frequency dependence by employing a time-derivative correction technique. Parameter estimation and model verification were subsequently carried out, demonstrating high accuracy of the derived model, keeping the deviation in the low percentage range (about 2- 3%). Finally, our model performance is demonstrated by an open loop compensation algorithm based on the inversion of the improved Preisach model.

Keywords: Control Application in Mechatronics, Identification and Estimation in Mechatronics, Motion Vibration and Noise Control
Abstract: A bi-stable spring component is proven to be able to improve the utilizable power from a vortex induced vibration (VIV) energy harvesting system at low speed water flows. However, it is also shown that chaotic vibrations might occur and drastically reduce the utilizable power when water flow velocity varies. Hence, an appropriate controller is required to maintain high-energy orbit vibrations when the system experiences chaos. The OGY chaos control method seems to be potential in this case since it only requires a small perturbation in a structural parameter. However, the requirement of a priori knowledge of all state variables makes the control design tedious and cost-expensive. To overcome this shortcoming, the time-delay coordinates have been proposed. As a tradeoff, the design and implementation might become more complicated. This paper carries out a comparative study between the two methods of using the full state variables and the time-delay coordinates to stabilize the chaotic responses of a bi-stable VIV energy harvesting system by means of the OGY method.

Keywords: Motion Vibration and Noise Control, Design Optimization in Mechatronics, Actuators in Mechatronic Systems
Abstract: The benefits of nonlinear damping in increasing the amount of energy (power) harvested by a vibration-based energy harvester (VEH) has been reported where it was revealed that more energy can be harvested using nonlinear cubic damping when compared to a VEH with linear damping. As has been reported, this only occurs when the base excitation on the VEH, at resonance, is less than the maximum base excitation. A maximum harvester base excitation results in a maximum distance the harvester mass can move due to its size and geometric limitations. The present study is concerned with the analysis and design of a VEH using a nonlinear frequency analysis method. This method employs the concept of the output frequency response function (OFRF) to derive an explicit polynomial relationship between the harvested energy (power) and the parameter of the energy harvester of interest, i.e. the nonlinear cubic damping coefficient. Based on the OFRF, a nonlinear damping coefficient can be designed to achieve a range of desired levels of energy harvesting. It is also shown that using the OFRF the harvester throw (the displacement of the mass of the harvester), can be predicted using the designed damping coefficient.

Keywords: Intelligent Sensors, Sensors and Sensing Systems, Mechatronics in Manufacturing Processes
Abstract: The need for wireless sensor networks that can run for long times without the need of battery replacement has risen the need for energy harvesters. Industrial environments have plenty of energy sources that can be harvested; pressure fluctuations are a high energy density source that can be harvested using piezoelectric devices. Present devices have introduced flat metallic plates as the main force transmission elements for hydraulic fluctuations energy harvesters. In this paper, we analyze the force transmission efficiency of flat plates when used as the primary fluid coupling interface in hydraulic energy harvesters. Previous work has been focused on the optimization of circuit matching and pressure ripple amplification. In this work, we offer a look into the efficiencies of flat plates in different configurations and pressure loads. The analysis shows that despite the reasonable force transmission efficiency of flat plates in low-pressure environments, the overall efficiency of hydraulic energy harvesters can be improved if instead of flat plates, conventional hydraulic actuators, such as piston cylinders, could be used.

Keywords: Micro-Electro-Mechanical Systems, Sensors and Sensing Systems
Abstract: A system level approach of a wearable rectified harvester array formed by integrating PVDF films and piezoelectric-charge-gated thin-film transistors (PCGTFTs) was addressed. Output power of the array upon various gratis non-stop daily trusts and body movements has been conducted. A peak power of a few !W from gentle finger bending is achieved. The analysis of voltage waveforms in response to both resistive and capacitive loads unveils that such an array is capable of quickly charging the capacitor and discharging it slowly allowing for possible energy storage. The estimation on power generation by the harvesting array and survey on power requirements for wearable electronic devices exhibit its feasibility for wearable electronics.

Keywords: Flexible Manipulators and Structures, Modeling and Design of Mechatonic Systems, Fuel Cells and Alternative Power Sources
Abstract: This paper presents a focus on harvesting energy from mechanical sources operating at 20Hz or below. For many practical energy harvesting applications, low frequency mechanical sources present an issue for efficient energy conversion. Often energy harvesters become inefficient when driven outside of a narrow band about their natural frequency, which may be orders of magnitude above the frequency of the target source. In this paper, an energy harvester is presented that combines the use of a piezoelectric stack mounted within a flexure frame, used to amplify the force applied to the piezoelectric elements. This force amplification serves to increase the low frequency, off-resonance performance of the device, achieving force amplification levels up to 7.95 times the input. This style of harvester is particularly suited to underfloor energy harvesting, typically targeting the motion of human or vehicle traffic overhead. In such an application, minimising the impact on the traffic is of high importance. Alternate methods of harvesting from such sources often involve mechanically driven systems, which can be disruptive or increase the required energy input. The proposed harvester addresses these known issues by offering a method of converting energy from very low levels of displacement. The harvester was proven to harvest energy from deflections of 112μm or less. In this work, the force amplification factor and the loaded displacement of the device are modelled using finite element analysis and experimentally proven. An iterative approach was taken using FEA software in order to optimise the force amplification of the harvester frame. The work serves to extend the knowledge of these devices to quantify their performance in the 0 – 20Hz range. Furthermore, the force amplification is explicitly simulated and proven experimentally, which has not previously been achieved in practice.

Keywords: Compuational Models and Methods, Flexible Manipulators and Structures
Abstract: Snake-like robots allow to perform examination tasks of difficultly accessible areas. In this context a hyper-redundant shaft concept based on unique binary, electromagnetic tilting actuators was proposed earlier. Because of the electromagnetic actuation principle, the system provides good path following capabilities in combination with high resistance against manipulation forces.

An efficient and intuitive path planning algorithm for those snake-like, serial chain robots is a follow-the-leader approach, as it is less complex and promises high accuracy at the same time. However, classical follow-the-leader approaches are designed for continuously actuated joints and their applicability to binary actuated systems is limited.

Therefore, an adaption to binary actuation with optimized switching sequences to achieve an appropriate path following performance in spatial settings despite of the restricted motion is presented in this paper. Optimization strategies are outlined and different cost functions for different use cases, including the adherence to constrains, are evaluated.

Keywords: Design Optimization in Mechatronics, Modeling and Design of Mechatonic Systems, Automotive Systems
Abstract: Improving fuel economy and reducing the Greenhouse-Gas emissions have been the determining factors in the development and implementation of innovative automotive technologies. Engine thermal management is one of the research fields that tries to solve these issues. Thermal management can be applied when controlling temperatures in different cooling circuits with an electronically actuated valve, which respects certain thermal management strategies. This control varies depending on several parameters such as temperature, load and engine rotational speed. This paper is part of a larger work that aims to improve the robustness of this valve design process since the early steps while minimizing the torque requirements of the DC-actuator. The first part of the paper will describe the mechanical concept of the valve and The second part will be focused on the hydro-mechanical model that is composed of four different sub-models that has been developed in order to simulate the multi-physical environment and so was validated based on experimental measurement. The third part is dedicated to discuss optimization results of a particle swarm based bi- objective optimization (PSO) loop applied on a simpler model, which helps to determine an optimal geometrical configuration. The optimal geometrical configuration found after running the optimization loop is to be tested in the multi-physical global model and results of the simulation are to be shown in future works.

Keywords: Sensors and Sensing Systems, Design Optimization in Mechatronics
Abstract: This paper describes a novel approach to the problem of optimal placement of 3D sensors in a specified volume of interest. The coverage area of the sensors is modelled as a cone having limited field of view and range. The volume of interest is divided into many, smaller cubes each having a set of associated Boolean and continuous variables. The proposed method could be easily extended to handle the case where certain sub-volumes must be covered by several sensors (redundancy), for example ex-zones, regions where humans are not allowed to enter or regions where machine movement may obstruct the view of a single sensor. The optimization problem is formulated as a Mixed-Integer Linear Program (MILP) utilizing logical constraints and piecewise linearisation of nonlinear functions. The final MILP problem is solved using the Cplex solver interfaced with Matlab.

Keywords: Design Optimization in Mechatronics
Abstract: The dual-drive H gantry is widely used in many industrial processes that require high precision Cartesian motion. The conventional rigid-link version suffers breaking down of joints if any de-synchronization between the two carriages occurs. To prevent above potential risk, a novel biaxial gantry with flexure-links is designed to allow a small rotation angle of the cross-arm. Nevertheless, the chattering of control signals and inappropriate design of the flexure joint will possibly induce resonant modes of the end effector. Thus, in this work, the design requirements in terms of tracking accuracy, biaxial synchronization, and resonant mode suppression are achieved by integrated optimization of the stiffness of flexures and PID controller parameters for a class of point-to-point trajectories with same dynamics but different steps. From here, an H2 optimization with defined constraints is formulated, and an efficient iterative solver is proposed by hybridizing direct computation of constrained projection gradient and line search of optimal steps. Comparative experiments results obtained on the testbed are presented to verify the effectiveness of proposed method.

Keywords: Control Application in Mechatronics, Modeling and Design of Mechatonic Systems
Abstract: Perturbation-based extremum seeking (ES) is a non model-based approach to maximize or minimize the output of a dynamic system without requiring any explicit information about the dynamics of the system, steady-state map, or the value of the extremum. In this work, perturbation-based ES is used to minimize power reflection from a cavity resonator in order to provide maximum accelerating field for particles travelling through the cavity. Power reflection is minimized by equalizing the frequency of the cavity and RF source. The controller sends commands to a stepper motor setup connected to the cavity. The stepper motor moves the tuner plate which changes the frequency of the cavity. Simulation and experimental results are presented which indicate that the algorithm can successfully minimize power reflection despite variations in the value of the minimum.

Keywords: Learning and Neural Control in Mechatronics, Control Application in Mechatronics
Abstract: In this paper, a distributed and cooperative optimization-based iterative learning control (ILC) algorithm is proposed for large-scale building temperature control problems. With the algorithm, large-scale building temperature control problems are solvable with reasonable computational load and guaranteed control performance under nearly repetitive disturbances. The large-scale centralized system is separated into several distributed and cooperative small-scale subsystems that communicate among each other. For each subsystem, a convex optimization problem is solved. The cooperative learning policy allows all subsystems to contribute together to improve the overall performance. The convergence property of the algorithm is proved and simulation results are provided to demonstrate its effectiveness.

Keywords: Planning and Navigation, Compuational Models and Methods, Service Robots
Abstract: This work proposes a novel RRT-based motion planning method for robotic systems equipped with redundant anthropomorphic arms. A characteristic Redundancy space (ReRRT) for this type of robots is proposed for sampling at the position level to deal with the problem of Task-Constrained Motion Planning (TCMP) with other multiple constraints in realistic robotic manipulation applications.

Based on the geometric feature of a redundant anthropomor- phic arm with seven DOFs, the whole configuration space of a robot equipped with the anthropomorphic arm is decoupled to extract a redundancy space independent of the task space. The redundancy space is defined and spanned by the swivel angle of the arm and the variables which control the position and orientation of the arm base frame located at the shoulder. As a result, an explicitly intuitive sampling space, which has one-to-one mapping relationship with the task-constrained configuration space, can be found. One dedicated Inverse Kinematics (IK) algorithm is developed to directly map the samples back to the task-constrained configuration space without iterative modifications. Simulation studies were performed and comparisons with traditional Gradient Projection Method (GPM) and Rapidly exploring Random Tree (RRT) are drawn to illustrate that the proposed ReRRT is able to combine the advantages of the two methods. Finally, an experimental task of putting a cup on the table is performed on a humanoid robot COMAN to demonstrate the effectiveness of the proposed method in a more realistic task scenario.

Keywords: Service Robots, Planning and Navigation, Mobile Robots
Abstract: In this study, we aim to achieve path-planning for firefighter robots in large petrochemical complexes. In large environments, path-planning (e.g., Hybrid A*) requires a large computation memory and a long execution time. These constrains are not feasible for firefighter robots. In order to overcome these two challenges, we propose a two-stage hybrid A* path-planning. For the first stage we use a global path-planner that makes a path using a low-resolution grid map of 2 m. The global path-planner generates a path for an area of approx. 500 m X 1000 m in 10 seconds . In the second stage, we refine the path by using a local-planner that uses a local-map of 100 m X 100 m size around the robot with a high resolution grid of 1 m. The local planner receives its sub-goal from the global planner and recalculates a local path at a high speed of a few hundred milliseconds. Therefore, the local-planner can react to changes of the map due to obstacles in real-time. We evaluated our proposed method by comparing with conventional hybrid A* in simulated as well as real experimental data of petrochemical complexes. By employing the local-planner our method could drastically reduce the used memory and execution time for the re-planning. For a trajectory of 600 m, our method reduces the execution time by 99.2% for real data and by 94.34% for simulated data. The memory usage was likewise drastically reduced by 97.45% for real data and by 97.91% for simulated data.

Keywords: Planning and Navigation, Aerial Robots, Compuational Models and Methods
Abstract: Many hybrid UAVs capable of vertical takeoff and landing (VTOL) and fixed-wing flight are being introduced for their maneuverability, efficiency and high cruise speed. The benefits of these systems can be exploited effectively using task planning frameworks tailored to their unique properties. To address this need, we present a motion planning strategy for these hybrid UAVs in cluttered urban settings. After dividing the flight into three phases of takeoff, cruise and landing, we solve each of the ensuing motion planning problems using Stable Sparse RRT motion planner. We employ a Dubin's vehicle based model because it offers a balanced trade-off between computational simplicity and accurate simulation of real-world behavior. Simulation experiments conducted in a dense urban setting (downtown Chicago) show the efficacy of our approach.

Keywords: Service Robots, Intelligent Process Automation
Abstract: Real manufacturing environments are cluttered spaces, where the environment matches its digital model (the CAD model) only to a certain degree. Robot systems, which autonomously execute tasks in these environments should combine CAD and vision data in order to successfully carry out their tasks. This way the model data (coming from the CAD model) can be corrected by the sensor data (coming from computer vision) to properly reflect the real environment. In this paper, a novel method for autonomous task-space exploration is presented, which is based on space exploration and object recognition. During the exploration of the environment, the CAD data is used to determine the initial belief of the newly gained information. After constructing the environment model, a task planner based on a geometric contact analysis and symbolic inference computes the necessary manipulation sequence. To compute the disassembly space, a novel time-efficient algorithm is proposed. The theoretical aspects are applied to disassembly sequences. A variety of heuristics for computing a local optimal sequence of the required manipulation steps and the corresponding paths is also presented in the paper. To plan the paths well-known global path planners are applied with a step-size control which reduce the planning effort. The approaches are experimentally validated and the results are discussed.

Keywords: Mobile Robots, Machine Vision, Planning and Navigation
Abstract: The robots in warehouse have boosted the efficiency and economic benefits of the logistic industrial chain. This paper provides a deep learning, single-camera-based solution to navigate vehicles in warehouse. Firstly we train a Faster R-CNN model to detect shelf-legs and tags in the captured image. To position the localized objects into the world coordinate, we then present a precise Inverse Perspective Mapping (IPM) algorithm. Finally, an unsupervised Support Vector Machine (SVM) algorithm is utilized to enumerate all possible paths and derive a best guiding line to navigate vehicles. The proposed solution is evaluated on real world warehouse images including various intricate situations. The experimental results prove the robustness and reliability of our work.

Keywords: Automotive Systems, Vehicle Technology, Service Robots
Abstract: In this paper, we propose a method to improve the accuracy of GPS positioning in the environment where the satellite signal including error information is excluded and the satellite signal is reflected and distorted like urban area. Factors that degrade GPS positioning accuracy include time error, ionospheric error, tropospheric error, and multipath error. In order to compensate for this, various methods such as RTK-GPS (Real Time Kinematic GPS), D-GPS (Differential GPS) and A-GPS (Assisted GPS) are used. However, these methods have drawbacks that are difficult to use due to additional system configuration and cost. In order to improve the position accuracy of the GPS receiver, the state of the satellite signal is determined by using the SNR and the Doppler shift, and the accuracy of the position estimation of the GPS receiver is improved by excluding the satellite signal including the error. In order to verify the performance of the proposed method, we proceeded with experiments under static conditions rather than dynamic conditions in a dense environment.

Keywords: Mobile Robots, Robot Dynamics and Control
Abstract: We propose a mobile robot that rolls by active deformation of the soft outer shell. The robot consists of a wire drive module and soft outer shell part that are joined only by prestressed wires. The soft shell and wire drive help realize a tough, low-cost, and lightweight design. To realize high-speed rolling, we examined the effect of property changes on the converged solution and rolling speed. Finally, we conduct a experiment with actual deformable robot.

Keywords: Robot Dynamics and Control, Mobile Robots, Control Application in Mechatronics
Abstract: This paper proposes a new kind of rolling mobile robot, consisting of a cylindrical outer shell and multiple autonomous mass-driver units inside it, each of which is capable of moving a mass along the radial axis. We design a simple decentralized (i.e., based only on local information) control law for individual unit, and theoretically show that the resulting motion would converge to constant-speed rolling depending on the choice of control parameters. Moreover, by extending this idea to three-dimensional, we propose a spherical rolling robot with radial mass-driver units, and designed a decentralized control law (inspired by phototaxis) to realize whole-body rolling and chasing for a given light source.

Keywords: Modeling and Design of Mechatonic Systems, Robot Dynamics and Control, Mobile Robots
Abstract: The authors showed that a motion generation is possible on downhill, by using the proposed method, through basic research of underactuated locomotion robot utilizing wobbling and sliding. It was, however, difficult to generate forward motion on level surface. Recently, our objective is motiongenerationonslipperylevelsurface,itisbeingdeveloped that a new type of the robot utilizing wobbling effects by quick return linkage. In this paper, we report the numerical simulation results and the parametric analysis results, and furthermore, the outline of the experimental robot is reported, it is under development. A motion of the quick return linkage and of the robot are shown as the numerical simulation. The moving speed of the robot with respect to driving frequency for the quick return linkage is shown as the parametric analysis.

Keywords: Control Application in Mechatronics, Mobile Robots
Abstract: The ultimate goal of a single-wheel mobile robot is to maintain balance and to navigate on its terrain autonomously. To become an autonomous vehicle, it is required to stand up and drive by itself. In this paper, a controllable balancing angle of the single-wheel mobile robot, GYROBO developed previously, is found by empirical studies. A dynamic equation of the gyroscopic effect between a gimbal and a body is verified by experimental studies. The physical relationship between the gimbal and the body system is studied. PWM(Pulse Width Modulation) characteristic of the control system, a maximum slew rate of gimbal and body, and the falling phenomenon of the robot are numerically analyzed by extensive experimental studies.

Keywords: Mobile Robots, Control Application in Mechatronics, Motion Vibration and Noise Control
Abstract: This paper presents a technique to design and implement a robust command shaper to reduce the residual vibration of a spherical rolling robot. The system of interest is VIRGO, a novel miniaturized spherical rolling robot designed for surveillance and reconnaissance. Given the high order nonlinearity of VIRGO, a second order linear approximation is first achieved through analysis of the system’s forced response. Subsequently, Zero Vibration (ZV), Zero Vibration with Derivative (ZVD), and Robust Variable Phase (RVP) shapers, including the Extra Insensitive (EI) Shaper, were designed and implemented. The performance of the robot’s unshaped and shaped responses were evaluated in terms of their settling time and maximum overshoot. Experimental results show that the proposed Robust Command Shaping technique is able to prevent flipping over while reducing residual vibration arising from a range of duty cycle inputs.

Keywords: Control Application in Mechatronics, Identification and Estimation in Mechatronics, Compuational Models and Methods
Abstract: In recent years, electric power assisted bicycles become popular in Japan. However the prices of such bicycles are still high because an expensive torque sensor is attached. It is a necessary component to measure human pedaling torque for comfortable motor assistance. Therefore realization of pedaling torque estimation without torque sensor is effective for the cost reduction. In our previous studies, we did not consider the condition for travelling on upward slope. In order to increase accuracy of the estimation regardless of road environmental change, this paper presents an improved method for pedaling torque estimation using the Recursive Least Square (RLS) method with multiple forgetting factors. The validity of the proposed method is verified by simulations and experiments.

Keywords: Motion Vibration and Noise Control, Identification and Estimation in Mechatronics
Abstract: A novel design of Composite Turbo-Molecular Pump (CTMP) is proposed. The major configuration of CTMP is composed by a coarse pump, a Turbo-Molecular Pump (TMP) and a Magnetic Gear Unit (MGU) capable of speed amplification. The corresponding modal analysis and the study on rotor/bearing dynamics are undertaken at first to estimate the resonance frequencies of the TMP blade rotor itself solely and the interactive dynamics of Blade Rotor/Radial Active Magnetic Bearing (BR/RAMB) subsystem. Secondly, an appropriate interval of stiffness provided and tuned by the RAMB is presented to make the TMP blade rotor able to actively retain speed margin at least 10% away from the resonance frequencies of the closed-loop control system. Thirdly, an economical and efficient method by adjusting the angular acceleration speed of BR, namely Resonance-Driven Prevention Strategy (RDPS), is proposed to avoid the undesired excitation at resonance frequencies of BR/RAMB system and potential instability. Finally, by intensive computer simulations, the proposed RDPS indeed manifests its outstanding performance to efficiently skip or bypass the natural frequencies of the closed-loop system within a very short time period and guarantee, to a certain extent, the system stability.

Keywords: Control Application in Mechatronics, Modeling and Design of Mechatonic Systems, Mechatronics in Manufacturing Processes
Abstract: In precision motion control systems, the two degree of freedom (2-DOF) control structure is widely utilized for improving tracking performance. Although ideally the 2-DOF control can be designed to yield zero tracking error, the practical performance is often deteriorated due to disturbances. In some cases, the disturbances can be measured or estimated and then compensated by modifying the control input. However, in many industrial applications, the control engineers are not allowed to modify the control input directly, as the commercial controllers are often proprietary with a closed architecture. In order to address this practical difficulty, in this paper, we propose a disturbance compensation scheme which alters the set-point instead of the control input. Since we no longer have a preview of the altered set-point, the traditional feedforward controller is no longer implementable due to its non-causality. The non-causality problem is then solved by using a predictive feedforward approach, which is based on prediction of the set-point as well as a general offsetting mechanism to compensate for the prediction errors. Simulations are conducted to further illustrate the proposed method with a case study based on a timing-belt tracking setup

Keywords: Control Application in Mechatronics, Mechatronics in Manufacturing Processes, Sensor Integration, Data Fusion
Abstract: In many laser processing applications, galvanometer scanners are integrated into a larger system that creates external disturbances to the actual laser-material interaction. To reject such disturbance with feedback-based control schemes, the sampling of the output needs to be fast enough to capture all major frequency components of the disturbance. In some applications, however, the sensor’s sampling speed is limited, such that the disturbance is beyond the sampler’s Nyquist frequency. This paper introduces a multi-rate control scheme to fully reject narrow-band beyond-Nyquist disturbances in galvanometer scanner systems. The proposed algorithm consists of a special bandpass filter with tailored frequency response, and a model-based predictor that reconstructs signals from limited sensor data. Verification of this algorithm is conducted by both simulated and experimental results on a commercial galvanometer scanner testbed.

Keywords: Modeling and Design of Mechatonic Systems, Novel Industry Applications of Mechatroinics, Motion Vibration and Noise Control
Abstract: In this paper, we propose a novel design of a compact unit of tunable vibration absorber with the integration of actuator, controller and sensor. It is a small design and can be attached simply to an existing application for a vibration suppression. The proposed system is a vibration absorber using a magnetorheological (MR) material, in which the stiffness can be tuned by controlling the external magnetic field. The previous magnetorheological material based vibration absorber has limitations in designing a compact unit due to the bulkiness in size, a necessity of a complex feedback sensor systems, and heating problem as the electromagnets are prone to overheating. Thus, this paper studies designs of an all-in-one unit of small vibration absorber that contains the MR material, the magnetic field generator and feedback sensor based on self-sensing property of the MR material. It is also free from heating problem even for a long-term application and provides easy installation. Two proposed designs are analyzed and compared with simulation and experimental data for the feasibility of the design.

Keywords: Modeling and Design of Mechatonic Systems, Identification and Estimation in Mechatronics, Motion Vibration and Noise Control
Abstract: Reaction wheel assembly (RWA) is an attitude control actuator for spacecraft. Its induced micro vibration will have a harsh effect on the performance of sensitive payloads. In this paper, a compact four-legged vibration isolation system for RWA is designed and investigated. Piezoelectric stack actuators (PSA) are chosen and dynamic equations are derived by Newton-Euler approach. Moreover, to identify low-frequency modal excitation of synthesis body composed by RWA and isolator, we propose one solution based on blind source separation (BSS). Simulation studies are conducted to verify the solution. The result shows that modal excitation within 10Hz-30Hz could be extracted effectively.

Keywords: Modeling and Design of Mechatonic Systems, Design Optimization in Mechatronics, Control Application in Mechatronics
Abstract: Camera technology is continuously improving and high quality cameras are now available under one pound of weight. This enables novel and innovative uses, for example at the end of a long boom pole. Unfortunately lighter cameras used in such ways are more susceptible to vertical disturbances and the bouncing associated with walking resulting in shaking and distortion. We introduce a miniaturized active stabilization mechanism that attenuates such disturbances and keeps the camera steady. Feedback control effectively emulates the stabilizing inertial dynamics associ- ated with higher weights without the penalty of higher weight. The system uses only accelerometer readings and avoids pure integration and associated numerical drift issues. We design, analyze, build, and test the mechanism to show appropriate performance.

Keywords: Fuzzy Logic, Intelligent Process Automation, Novel Industry Applications of Mechatroinics
Abstract: Constant torque control in machining processes reduces the cycling time and energy consumption, while protecting the machine tool and cutting tool at the same time. This paper presents an adaptive fuzzy control system for optimizing the cutting torque in gear hobbing process. And during the machining process, the input and output scaling factors of the fuzzy controller can also be adjusted automatically according to the control effect. Therefore, this control system can achieve robust adaptive control of the spindle torque by regulating the feed rate in gear hobbing process with little intervention of humans. As a result, the fluctuation of the cutting torque in gear hobbing process is reduced and the machining efficiency is improved significantly.

Keywords: Rehabilitation Robots, Modeling and Design of Mechatonic Systems, Robot Dynamics and Control
Abstract: Active exoskeleton controllers are designed to control the interaction force. Compliant exoskeletons need to be controlled in both position and force due to the coupling with a human in all rehabilitation conditions, which give rise to human-exoskeleton interaction dynamics, high nonlinear uncertain exoskeleton dynamics, noisy sensors and other parametric uncertainties, such as environmental contacts. These factors do not allow to account on a precise dynamical model, thus model-based controllers are difficult to implement. This paper presents an auto-tuning force/position controller based on fuzzy inference system to control a previously designed five degrees of freedom upper limb exoskeleton. The exoskeleton control system aims to achieve the best control performances together with stability and safety guarantees.

Keywords: Fuzzy Logic, Robot Dynamics and Control
Abstract: This paper revisits the problem of global asymptotic regulation for robot manipulators with bounded inputs. A simple model-free sectorial fuzzy controller plus saturated integral action is proposed. Global asymptotic stability is proven following Lyapunov’s direct method. Advantages of the proposed control are that it is fairly easy to construct with simple intuitive structure and absence of modeling parameter, and thus it is ready to implement. An additive appealing feature is that the proposed control has the abilities to protect the actuator from control effort saturation and ensure global asymptotic stability. Simulations on a two-DOF robot demonstrate the effectiveness of the proposed approach.

Keywords: Robot Dynamics and Control, Control Application in Mechatronics, Novel Industry Applications of Mechatroinics
Abstract: We propose an enhanced time-delay controller (TDC) for robot manipulators using Takagi-Sugeno-Kang (TSK) fuzzy control systems. The proposed controller has three terms: a time-delay estimation (TDE) term to estimate and cancel continuous nonlinearities of robot dynamics, a desired dynamics injection term, and a TSK fuzzy inference system to correct the effect of the TDE error. The TSK-type fuzzy inference system is constructed by using integral sliding surface to achieve the desired error dynamics. The proposed controller is easy to implement because calculations of the robot dynamics are not required, and the design of the fuzzy rules is also intuitive. The proposed controller has shown enhanced tracking performances compared with the conventional TDC in the experiment.

Keywords: Control Application in Mechatronics, Compuational Models and Methods, Automotive Systems
Abstract: The paper presents an optimal control strategy for a heavy-duty multi-group transmission that allows for simultaneous shifting in all groups. The approach is presented for a two-group transmission without loss of generality. The optimal control problem (OCP) consists of three phases with state-dependent switching of the hybrid dynamics and free end-time characteristics as well as several input and state constraints. The objective is designed to minimize the gear shift time while maintaining the speed and torque at the output shaft. A tailored optimization algorithm is presented to numerically solve the nonlinear OCP in a highly efficient manner. A comparison with a standard SQP method as well as simulation and runtime results on CPU and ECU level demonstrate the performance of the algorithm for an embedded real time implementation.

Keywords: Robot Dynamics and Control, Control Application in Mechatronics
Abstract: In this contribution, we propose a novel nonlinear Model Predictive Control (NMPC) formulation based on the optimal control method Discrete Mechanics and Optimal Control (DMOC). We discuss the properties of the novel approach and compare it with the standard NMPC formulation based on the Multiple-Shooting method using numerical simulations. We also consider the real-time application of the NMPC algorithm by extending the DMOC based NMPC using the Real-Time Iteration scheme. We apply the extended NMPC controller to the swing-up and stabilization task of a double pendulum on a cart with limited rail length to show its capability for controlling nonlinear dynamical systems with input and state constraints.

Keywords: Control Application in Mechatronics, Compuational Models and Methods, Robot Dynamics and Control
Abstract: A difficulty still hindering the widespread application of Model Predictive Control (MPC) methodologies, remains the computational burden that is related to solving the associated Optimal Control (OC) problem for every control period. In contrast to numerous approximation techniques that pursue acceleration of the online optimization procedure, relatively few work has been devoted towards shifting the optimization effort to a precomputational phase, especially for nonlinear system dynamics. Recently, interest revived in the theory of general Polynomial Chaos (gPC) in order to appraise the influence of variable parameters on dynamic system behaviour and proved to yield reliable results. This article establishes an explicit solution of the multi-parametric Nonlinear Problem (mp-NLP) based on the theoretical framework of gPC, which enabled a polynomial approximated nonlinear feedback law formulation. This resulted in real-time computations allowing for real-time MPC, with corresponding control frequencies up to 2 kHz,

Keywords: Control Application in Mechatronics, Automotive Systems
Abstract: This contribution demonstrates the practical realizability of a tailored real-time nonlinear model predictive control (MPC) scheme for off-highway diesel engines. Besides controlling the torque and emissions, the MPC accounts for inequality constraints such as the maximum cylinder pressure by means of an augmented Lagrangian formulation. In addition, the heat-up of the exhaust gas aftertreatment system, e.g. for the regeneration of a diesel particulate filter, is acilitated with a warm-start strategy that enables the smooth activation of the inequality constraints. Experimental results from a testbench of the off-highway diesel engine within a wide operation range demonstrate the efficiency of the control scheme.

Keywords: Control Application in Mechatronics, Robot Dynamics and Control, Motion Vibration and Noise Control
Abstract: Variable stiffness actuation is a new design paradigm for high performance and energy efficient robots with inherent safety features. Nonlinear model predictive control (NMPC) was employed to control these robots due to its ability to cope with constrained and nonlinear systems. Even though the results for NMPC are promising, one major weakness is the computational cost of this algorithm. It restricts the use of NMPC to low degree of freedom robots with relatively slow dynamics. This problem can be alleviated by finding an approximate linear representation of the system and using less computation hungry traditional model predictive control (MPC). In this work, we present our successive linearization based MPC (SLMPC) framework for variable stiffness actuated (VSA) robots. The system is linearized and discretized at every sampling instant and a quadratic problem is formulated using this discrete-time linear model. Solution of this quadratic problem provides the control inputs for the control horizon. In order to compare our scheme to NMPC, we conducted experiments with a reaction wheel augmented VSA system. For a 16 s trajectory tracking experiment, the root-mean-square errors were 0.54 and 0.64 degrees for NMPC and SLMPC methods, respectively, whereas the average computation time of the control rule was 2.17 ms for NMPC and 1.25 ms for SLMPC. Halving the computation time without compromising tracking performance shows the potential of our approach as a viable control alternative for VSA robots.

Keywords: Control Application in Mechatronics, Robot Dynamics and Control
Abstract: Widespread application of real-time, Nonlinear Model Predictive Control (NMPC) algorithms to systems of large scale or with fast dynamics is challenged by the high associated computational cost, in particular in presence of long prediction horizons. In this paper, a fast NMPC strategy to reduce the on-line computational cost is proposed. A Curvature-based Measure of Nonlinearity (CMoN) of the system is exploited to reduce the required number of sensitivity computations, which largely contribute to the overall computational cost. The proposed scheme is validated by a simulation study on the chain of masses motion control problem, a toy example that can be easily extended to an arbitrary dimension. Simulations have been run with long prediction horizons and large state dimensions. Results show that sensitivity computations are significantly reduced with respect to other sensitivity updating schemes, while preserving control performance.