A forearm actuation unit for an upper extremity prosthesis

This paper presents the design of a 14 degree-of-motion forearm actuation unit for an upper extremity prosthesis. The forearm utilizes pneumatic type actuators which use the reaction products of a monopropellant gas generator as a working fluid. The use of pneumatic type actuators provides a near-human power density, such that the fourteen actuator forearm unit can deliver approximately one half of the force and power capability of a human arm, with a total package size that fits within the volumetric constraints of a 50th percentile female forearm (excluding the cartridge of liquid propellant). This paper describes the design of the forearm. The design has been fabricated, and experimental results are presented that demonstrate the closed-loop force tracking capability. An accompanying video further demonstrates the forearm performance.