Design and experimentation of shape memory alloy wire bundle actuators

Current literature describes the use of multiple muscle wires placed in parallel to increase the lifting capabilities of a Shape Memory Alloy (SMA) actuator. Toward this end, this research studied the design and development of SMA muscle wire bundle actuators, encompassing two areas: 1) the optimization of bundle design and 2) the development and comparison of varied bundle actuators. To date, bundle arrangement has been limited to wires of like-diameter. The first part of this paper describes the formulation of a constrained optimization problem that explored the use of several different diameter wires for an optimal SMA bundle actuator. The final section of this paper presents the experimental results of several configurations consisting of series of wires placed in parallel, joined or intertwined and crimped together, or bundled separately. As a case study, the design and development of SMA bundle actuators for the Rutgers robotic hand is presented.