Session: MR-07-04: Novel Mechanisms, Robots, & Applications

Paper Number: 196444

196444 - A Two-Speed Robotic Actuator Transmission Based on Opposing Unidirectional Clutches 

Despite advances in brushless motor technology, the dynamic range of robotic actuation lags behind that of biological actuation, particularly with respect to peak torque output relative to minimum torque, where the latter is typically determined by the minimum output impedance of the actuator during passive movement. This presentation describes a two-speed transmission for a robotic actuator that substantially expands the dynamic range of actuator output, in terms of torque, speed, and reflected impedance, relative to a typical single-speed actuator. The transmission switches between gear ratios via selective locking and unlocking of planetary components using opposing sets of actuated one-way roller clutches. This clutching architecture enables high holding torque with very compact and low power clutch actuation. In addition to the favorable clutch actuation requirements, the opposing sets of actuated one-way clutches provide access to asymmetric configurations, which have unique gear-shifting properties. In particular, these asymmetric configurations automatically perform instantaneous gear shifts at the moment the output velocity reverses directions. Since the reversal occurs at exactly zero velocity, which always fulfills the speed-matching condition needed for a smooth gear shift, the gear shift occurs at the instant of speed-matching, producing a smooth shift without any precisely timed control input. This presentation will describe the conceptual design of the proposed two-speed transmission using opposing unidirectional clutches.

Presenting Author: Aaron Haake Vanderbilt University

Presenting Author Biography: Aaron Haake received the B.S. degree in mechanical engineering from the University of Nebraska-Lincoln in 2022. He is currently pursuing the Ph.D. degree in mechanical engineering at Vanderbilt University. His research involves design of lower-limb prosthetic devices, particularly focusing on actuator design.