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Volume 21 Issue 04 - Publication Date: 1 April 2002
 
Artificial Muscles : Actuators for Biorobotic Systems
 
Glenn K. Klute Dept. of Veterans Affairs, Puget Sound Health Care System, USA and Dept. of Electrical Engineering, University of Washington, USA , Joseph M. Czerniecki Dept. of Veterans Affairs, Puget Sound Health Care System, USA and Dept. of Rehabilitation Medicine, University of Washington, , USA and Blake Hannaford Dept. of Electrical Engineering, University of Washington, USA
 
Biorobotic research seeks to develop new robotic technologies modeled after the performance of human and animal neuromuscular systems. 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 mathematically 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 concentric 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.
 
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