Application of Shape Memory Alloy Actuators in Active Shape Control of Inflatable Space Structures

SMA (shape memory alloy) actuators have found a wide range of applications due to their unique properties such as high force, long stroke, small size, light weight, and silent operation, etc. However, their strong nonlinear properties make them a challenge to achieve accurate actuation. This paper presents a simple control strategy based on the idea of adjusting the SMA wire temperature as fast as possible. This strategy is simple, stable, and requires no hysteresis model or thermal model. This strategy is tested with displacement output, and effects of updating rate and input current on control accuracy are also discussed. This control strategy is then used for active shape control of inflatable space structures. Results indicate that under this control strategy, shape memory alloy wire actuators can offer very good accuracy, and for inflatable structure shape control, great improvement can be achieved.