Robust and Adaptive Sampled-Data Control of Twisted and Coiled Artificial Muscles

Twisted and Coiled Artificial Muscles (TCAMs) are lightweight actuators providing high power/weight ratio, and can substitute heavy electromagnetic motors and pneumatic artificial muscles in applications that require low weight and high contractile work. In this letter we present a robust and adaptive output feedback control strategy for electro-thermally actuated TCAMs. The controller adjusts the voltage applied to the TCAM in order to match desired muscles contraction/expansion. The proposed controller compensates for disturbances and uncertainties in the TCAM's dynamic model. The robustness and stability analysis of the controller takes into account a digital implementation of the control algorithms. Performance are derived in terms of the sampling time of the CPU and the sensors available. The efficacy of the controller is validated through experimental tests.