Clutchable series-elastic actuator: Design of a robotic knee prosthesis for minimum energy consumption

• Published in: 2013 IEEE 13th International Conference on Rehabilitation Robotics (ICORR) Vol. 2013; pp. 1 - 6
• Main Authors: Rouse, Elliott J., Mooney, Luke M., Martinez-Villalpando, Ernesto C., Herr, Hugh M.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: United States IEEE 01-06-2013
• Subjects: Actuators; biologically inspired design; Biomechanical Phenomena; clutch; Elasticity; Energy Transfer; Humans; Kinematics; Knee; Knee Prosthesis; Legged locomotion; lower limb prosthesis; Models, Theoretical; powered prosthesis; Prosthesis Design; Prosthetics; Robotics - instrumentation; Robotics - methods; series elastic actuator; Torque; Walking - physiology
• ISBN: 9781467360227; 1467360228
• ISSN: 1945-7898; 1945-7901
• DOI: 10.1109/ICORR.2013.6650383

The cyclic and often linear torque-angle relationship of locomotion presents the opportunity to innovate on the design of traditional series-elastic actuators (SEAs). In this paper, a novel modification to the SEA architecture was proposed by adding a clutch in parallel with the motor within the SEA - denoted as a CSEA. This addition permits bimodal dynamics where the system is characterized by an SEA when the clutch is disengaged and a passive spring when the clutch is engaged. The purpose of the parallel clutch was to provide the ability to store energy in a tuned series spring, while requiring only reactionary torque from the clutch. Thus, when the clutch is engaged, a tuned elastic relationship can be achieved with minimal electrical energy consumption. The state-based model of the CSEA is introduced and the implementation of the CSEA mechanism in a powered knee prosthesis is detailed. The series elasticity was optimized to fit the spring-like torque-angle relationship of early stance phase knee flexion and extension during level ground walking. In simulation, the CSEA knee required 70% less electrical energy than a traditional SEA. Future work will focus on the mechanical implementation of the CSEA knee and an empirical demonstration of reduced electrical energy consumption during walking.