An architecture for fast and accurate control of shape memory alloy actuators

This paper presents a new control architecture for fast, accurate force control of antagonistic pairs of shape memory alloy wires. The main components are: a differential-mode controller which controls the output force, an anti-slack mechanism, a rapid-heating mechanism and an anti-overload mechanism. The closed-loop response is fast and accurate, even in the presence of large external motion disturbances. There is no sign of limit cycles, and the performance is unaffected by large load inertias. This paper also presents an architecture for position control, in which a position feedback loop is added to the force control architecture. Experimental results show force control accuracies as high as 1 mN in a 13 N range, force output rates as high as 50 N s²¹, and highly accurate position control with steady-state errors below the resolution of the position encoder.