ICRA 2011 Paper Abstract


Paper ThA107.4

Jafari, Amir (Italian Institute of Technology), Tsagarakis, Nikolaos (Italian Institute of Technology (IIT)), Caldwell, Darwin G. (Italian Institute of Technology)

AwAS-II: A New Actuator with Adjustable Stiffness Based on the Novel Principle of Adaptable Pivot Point and Variable Lever Ratio

Scheduled for presentation during the Regular Sessions "Variable Stiffness Actuators I" (ThA107), Thursday, May 12, 2011, 09:05−09:20, Room 5B

2011 IEEE International Conference on Robotics and Automation, May 9-13, 2011, Shanghai International Conference Center, Shanghai, China

This information is tentative and subject to change. Compiled on May 23, 2019

Keywords Compliant Joint/Mechanism, Mechanism Design of Manipulators


The Actuator with Adjustable Stiffness (AwAS) is an actuator which can independently control equilibrium position and stiffness by two motors. The first motor controls the equilibrium position while the second motor regulates the compliance. This paper describes the design and development of AwAS-II which is an improved version of the original realization. AwAS tuned the stiffness by controlling the location of the springs and adjusting its arm, length. Instead AwAS-II regulates the compliance by implementing a force amplifier based on a lever mechanism on which a pivot point can adjust the force amplification ratio from zero to infinitive. As in the first implementation, the actuator which is responsible for adjusting the stiffness in AwAS II is not working against the spring forces. Its displacement is perpendicular to the force generated by springs which makes changing the stiffness energetically efficient. As the force amplification ratio can theoretically change from zero to infinitive consequently the level of stiffness can tune from very soft to completely rigid. Because this range does not depends on the spring’s rate and length of the lever, thus soft springs and small lever can be used which result in a lighter and more compact setup. Furthermore as the lever arm is shorter the time required for the stiffness regulation is smaller.



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