Variable Transmission Compliance With an MR Damper

This paper presents a novel transmission design that consists of a parallel combination of an MR damper and a compliant element together acting in series with an actuator. By adjusting the magnetic field to vary the amount of damping, the transmission can be switched between compliant and effectively rigid modes. Transmission compliance between an actuator and its load has several benefits: It enables (1) storage of elastic energy to improve efficiency, (2) filtering of shocks acting on the load that would otherwise be transmitted to the actuator, and (3) facilitation of force control by converting it to a position control problem. Despite these benefits, the design objective for most robotic systems remains to minimize transmission compliance to improve transmission bandwidth, improving the ability to control the position of the load with high precision. With the new transmission presented in this paper, compliance becomes a tunable quantity allowing joint stiffness to be optimized based upon the task requirements.Copyright © 2004 by ASME