title: Clutchable series-elastic actuator: design of a robotic knee prosthesis for minimum energy consumption.
abstract: 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.
authors.forename: Elliott J
authors.initials: EJ
authors.lastname: Rouse
authors.forename: Luke M
authors.initials: LM
authors.lastname: Mooney
authors.forename: Ernesto C
authors.initials: EC
authors.lastname: Martinez-Villalpando
authors.forename: Hugh M
authors.initials: HM
authors.lastname: Herr
mesh_terms: D001696:Biomechanical Phenomena; D004548:Elasticity; D004735:Energy Transfer; D006801:Humans; D007720:Knee Prosthesis; D008962:Models, Theoretical; D011474:Prosthesis Design; D012371:Robotics / Q000295:instrumentation* / Q000379:methods*; D019415:Torque; D016138:Walking / Q000502:physiology*