System Analysis And Control Of SMA Actuating Systems

Shape Memory Alloys(SMA)as a new kind of smart materials,may also produce deformation and recovery tension through inflicting the phase changes through the changes of material temperature,and thus the SMA can achieve the convert of thermal energy and mechanical energy.The special actuated characteristics of the SMA makes the SMA actuators have wonderful characteristics such as high power density ratio and high resilience,so it has steadily been applied in the fields of bionic robots and aerospace.In this thesis,the modelling and control method for the SMA based actuating system is discussed.However,there are strong saturation hysteresis nonlinear characteristics between the input and output of the SMA actuators due to the special properties inside the material,thus characteristic will result in the decline of actuators output accuracy,oscillation and even instability,which limits the improvement of actuators performance.Considering the hysteresis effect inside the SMA wire,the composite control scheme of feedforward control and feedback control is proposed.In the feedforward control,the hysteresis inverse model is constructed based on the Duhem model to compensate the hysteresis.The adaptive Sliding mode control method is designed in a nonlinear control refuge that drives the systems state trajectory on to a specific sliding surface and maintain the trajectory on this surface for the following time.The main tasks of this thesis are as follows: In this paper,the characteristics of the shape memory alloy intelligent flexible actuator are selected as the controlled object development,from the shape memory effect of the SMA wire,the mechanical characteristics,the working principle of the SMA driver,the input and output characteristics of the SMA driver and hysteresis.In this paper,a new SMC controller with PID-type sliding and adaptive gains is proposed for the motion tracking of an actuated micromanipulator hysteresis modeling systems.It can be that the sliding mode controller proposed in this paper has a good tracking effect,the tracking error and the adjustment time of the control systems.