Abstract: A plurality of shape memory alloy tubes (SMTs) of one or more shape memory alloy (SMA) types is configured as an element in a rotary actuator system in a nested manner. In various configurations, the nested SMTs provide one or more modes of multiplication (torque output or angular displacement), rotation reversibility and bias loading. The innovation provides for leveraging the modes for reductions in the rotary actuator system size, weight, or complexity or combinations thereof, or providing improved and more stable actuation capabilities in a given envelope.

Abstract: A scalable plurality of shape memory alloy (SMA) elements are configured to provide a continuous rotation actuator system. The plurality of SMA elements are coupled to a Ring Gear element, as well as to a Sun Gear element and a provision for thermal cycle return assist of the SMA elements. A plurality of Transmission elements provide for controlled rotary actuation in a desired direction with lock capability that provides for continuous rotary motion even as the SMA elements undergo reciprocating rotary action during their thermal cycling without running into system component rotation limits. The innovation distinguishes over other innovative approaches by way of at least the Ring Gear element, the manner of lock control, and the return assist element.