Disturbance Compensation Based Force and Position Control of Prosthesis Finger Actuated by Shape Memory Alloy

The intelligent material shape memory alloy (SMA) contributes to driving prosthetic finger systems. However, the dynamic properties of SMAs impact the precise control of force and position. In this paper, a first order driving force mechanism model is presented, and a force adaptive control method based on disturbance compensation is proposed. Then, a double closed-loop adaptive position control structure is applied. The tracking experiments of step signal, frequency conversion sinusoidal signal, and triangle wave signal are carried out on a prosthetic finger platform, which shows that the proposed method can adapt to the complex kinetic properties of memory alloys. At the same time, the load disturbance resistance experiment further proves that the proposed method can effectively suppress the system disturbance with strong robustness.