Artificial Muscles: Actuators for

Biorobotic research seeks to develop new robotic technologies mod-eled after the performance of human and animal neuromuscular sys-tems. The development of one component of a biorobotic system, an artificial muscle and tendon, is reported here. The device is based on known static and dynamic properties of biological muscle and tendon that were extracted from the literature and used to mathe-matically describe their force, length, and velocity relationships. A flexible pneumatic actuator is proposed as the contractile element of the artificial muscle and experimental results are presented that show the force-length properties of the actuator are muscle-like, but the force-velocity properties are not. The addition of a hydraulic damper is put forward to improve the actuator’s velocity-dependent properties. Further, an artificial tendon is set forth whose function is to serve as connective tissue between the artificial muscle and a skeletal structure. A complete model of the artificial muscle-tendon system is then presented which predicts the expected force-length-velocity performance of the artificial system. Experimental results of the constructed device indicate muscle-like performance in general: higher activation pressures yielded higher output forces, faster con-centric contractions resulted in lower force outputs, faster eccentric contractions produced higher force outputs, and output forces were higher at longer muscle lengths than shorter lengths