Design and Preliminary Results of a Reaction Force Series Elastic Actuator for Bionic Knee and Ankle Prostheses

We present an actuator designed for untethered, lower-extremity powered-prostheses that replicates biological kinetic and kinematic function of both human knees ankles. An electric energy optimal hardware specification is defined by kinematically clamping walking gait data to the dynamic model a series elastic (SEA) searching motor, reduction ratio, spring. The shown achieve required torque, angle, velocity requirements nominal conditions on level ground as well varied terrain. performance demonstrated benchtop worn subject with unilateral below knee amputation. resulting design moment-coupled cantilever-beam reaction-force SEA (MC-RFSEA) has torque rating 85Nm, repeated peak 175Nm, 105 o range motion, mass 1.6kg. Preliminary results from level-ground tested in ankle configuration show cost transport 0.053J/kg when at 1.5m/s.