Sleeve Muscle Actuator: Concept and Prototype Demonstration

This paper presents the concept and prototype demonstration results of a new sleeve muscle actuator, which provides a significantly improved performance through a fundamental structural change to the traditional pneumatic muscle. Specifically, the sleeve muscle incorporates a cylindrical insert to the center of the pneumatic muscle, and thus eliminates the central portion of the internal volume. Through the analysis of the actuation mechanism, it is shown that the sleeve muscle is able to provide a consistent increase of force capacity over the entire range of motion. Furthermore, the sleeve muscle provides a significant energy saving effect, as a result of the reduced internal volume as well as the enhance force capacity. To demonstrate this new concept, a sleeve muscle prototype was designed and fabricated. Experiments conducted on the prototype verified the improvement in the force capacity and demonstrated a significant energy saving effect (20%–37%). Finally, as the future work on this new concept, the paper presents a new robotic elbow design actuated with the proposed sleeve muscle. This unique design is expected to provide a highly compact and powerful actuation approach for robotic systems.