Series Elastic Actuators - Intelligent Robots and Systems 95. 'Human Robot Interaction and Cooperative Robots', Proceedings.

It is traditional to make the interface between an actuator and its load as stiff as possible. Despite this tradition, reducing interface stiffness offers a number of advantages, including greater shock tolerance, lower reflected inertia, more accurate and stable force control, less inadvertant damage to the environment, and the capacity for energy storage. As a trade-off, reducing interface stiffness also lowers zero motion force bandwidth[9][10]. In this paper, we propose that for natural tasks, zero motion force bandwidth isn’t everything, and incorporating series elasticity as a purposeful element within an actuator is a good idea. We use the term elasticity instead of compliance to indicate the presence of a passive mechanical spring in the actuator. After a discussion of the trade-offs inherent in series elastic actuators, we present a control system for their use under general force or impedance control. We conclude with test results from a revolute series-elastic actuator meant for the arms of the MIT humanoid robot Cog[5] and for a small planetary roveri21.’