Position Control of a Flexible Beam Actuated by Two Active SMA Wires

SMA-actuated flexible structure become nonlinear in large deflection mode and as a result become more sensitive to the actuator applied force. In order to overcome this problem, in this paper, the hysteresis nonlinearity of SMA-actuated flexible structure is modeled by the generalized PrandtlIshlinskii model. Subsequently, a feedforwardfeedback controller is used to control the tip deflection of the SMA-actuated structure. The feedforward part of the control system is based on the inverse generalized PrandtlIshlinskii model while a conventional proportionalintegral feedback controller is added to the feedforward controller to increase the accuracy. However, in order to increase accuracy of position control system, in addition to the main SMA actuator, another auxiliary SMA actuator is attached to the structure. It is shown by the experimental data that, in comparison to the time that only main SMA actuator is attached to the structure, the proposed controller in the new architecture has increased the accuracy of the position control system.