Research On Modeling And Control Of IPMC Actuators' Hysteresis Characteristics

Ionic Polymer Metal Composite(IPMC)is one of the intelligent materials.This kind of materials can achieve bending deformation driven by an external electric field and recover to its initial state when the electric field is removed.As actuators,IPMC has the characteristics that include low driving voltage(1V-5V),fast response,large driving deformation,light weight,good flexibility,better performance in the water environment and so on.Therefore,IPMC actuators possess a very broad application prospect in the fields of bionics,biomedicine and micro-electromechanical systems.However,IPMC has strong-nonlinearity,especially hysteresis,which affects the control accuracy seriously.In this thesis,firstly,the IPMC actuator with platinum electrode is firstly prepared,and the electrical drive performance is tested to observe its tip displacement response under different voltage drives,so as to analyze and summarize the hysteresis characteristics of the IPMC actuator.Secondly,a LSSVM-NARX(least squares support vector machine-nonlinear autoregressive)model is proposed and MATLAB simulation is used to compare this model with a prandtl-ishlinskii model,which is frequently used at present.The LSSVM-NARX model has been proved to have better modeling effect.Finally,the model is optimized by using artificial colony algorithm.Then,a LSSVM-NARX inverse controller is designed to compensate the hysteresis characteristics of IPMC actuator.After analyzing the performance of the inverse controller according to the simulation results,a PID feedback controller is added and they combine to form a hybrid PID feedback controller.MATLAB simulation results show that the control scheme has excellent performance.Finally,the experimental platform based on DSP is established.The experimental results show that the designed hybrid PID feedback controller can compensate the hysteresis characteristics of IPMC actuator well and achieve accurate control.