Study Of A High-precision Servo Control Method

With the rapid development of semiconductor manufacturing, nano-materials andhigh-precision measurement, piezoelectric ceramic high-precision positioningtechnology plays an increasingly important role in many areas. But the stronghysteresis of piezoelectric ceramic has a serious impact on the control accuracy. Inthis thesis, the reaserch focuses on the high-precision piezo servo system. Itsnonlinear hysteresis model and control method, and their practical verifications havebeen completed.Firstly, the static hysteresis characteristics of the high-precision piezo servosystem is described by Bouc-Wen model. The model structure is simple and has lessparameters to identify. Then the details of the procedure to identify Bouc-Wenhysteretic with PSO algorithm is described and a static Bouc-Wen hysteresis model isestablished. The simulation result shows that the model has a high fitting precisionand is able to reflect the static hysteresis characteristics of the high-precision piezoservo system.The problem of current control system is their complex structure and badimplementation. To deal with the problem, a control system is proposed, whichcombines a hysteresis compensator based on Bouc-Wen hysteresis model with asliding mode controller based on a perturbation estimator. The hysteresiscompensator is settled in cascade with the process approximately cancelling thehysteresis nonlinearity and reducing a nonlinear system to a linear system with aninversion error. The compensation error and other uncertainties will be dealt with bythe sliding controller in the feedback path. The simulation results show that theproposed control system can effectively improve the control performance and theentire control system not only has a good control effect, but also has a simplestructure and is easy to set up the implementation.In order to further improve the control accuracy, a control system combing ahysteresis compensator based on the improved hysteresis PI model with abackstepping controller based on purterbation estimator is proposed. The improved PI model has better fitting precision. The backstepping controller based on thepurterbation estimator has a better control effect. The simulation results show thatthe control system can effectively improve the accuracy of the tracking platform.Finally, an experimental system based on iHawk semi-physical simulationplatform for the verification of the designed algorithms is settled. Experimentalresults show that the experimental results are consistent with the simulation results,verify the effectiveness of the designed control system and lay the foundation forfuture research work.