Variable structure control of shape memory alloy actuators

摘要: A shape memory alloy (SMA) actuator consisting of a number thin NiTi fibers woven in counter rotating helical pattern around supporting disks is first described. This structure accomplishes highly efficient transformation between force and displacement overcoming the main mechanical drawback alloys, that being limited strain. Time domain open loop experiments were then conducted to determine intrinsic properties actuator. From these from knowledge underlying physics SMAs, multiterm model, including linear nonlinear elements, was proposed. After further investigation simulation, it found most complexities did not need be considered order explain reported results, model could reduced single integrator. variable controller applied pair antagonist actuators. The feedback switches two actuators according sign error. improvement added compensate for known gross nonlinearities by modulating current magnitude discrete manner as function state space position. It therefore possible realize smooth robust control with very little cost complexity.