Research On Characteristic Modeling And Control Of Piezoelectric Actuator Under Complicated Working Conditions

Micro-actuating systems have become an important part of related fields such as robotics,precision manufacturing and medical fields.As one of the candidates for high-precision actuating components in micro-actuating systems,piezoelectric actuators with high displacement resolution,large output power,and fast response speed show the obvious advantages in improving the actuating performance of mechanical systems.However,piezoelectric actuator made of piezoelectric materials has strong frequency-dependent hysteresis nonlinearity characteristic inside,which is the main factor hindering the improvement of the actuating accuracy of piezoelectric actuator.In this paper,the piezoelectric actuating platform based on piezoelectric actuator is taken as the research object.Considering the hysteresis nonlinearity characteristic existing in the piezoelectric actuator,a modeling method combining the Modified Particle Swarm Optimization(MPSO)algorithm and Rate-dependent Prandtl-Ishlinskii(RDPI)model is designed to determine the hysteresis nonlinear model of the piezoelectric actuating platform.And based on this model,an adaptive backstepping controller was designed to realize the trajectory tracking of the piezoelectric actuating platform under the premise of ensuring the stability of the closed-loop system.Further considering the input constraints of piezoelectric actuator in practical application,an anti-windup compensator is introduced into the unsaturated control scheme,which can effectively alleviate the performance degradation of controller when input saturation occurs.The main work completed in this paper is as follows:1)Completed the experimental research on the input and output characteristics of the piezoelectric actuating platform.In order to model the hysteresis nonlinearity existing in the piezoelectric actuating platform to accurately predict the output behavior of the piezoelectric actuating platform in a wide frequency range,this paper has completed the experimental research on the input and output characteristics of the piezoelectric actuating platform with the change of input signal frequency and amplitude,and analyzed the hysteresis nonlinearity characteristics of the piezoelectric actuating platform combining with the experimental results.2)A hysteresis modeling method combining MPSO algorithm and RDPI model is designed.The piezoelectric actuator is separated from the piezoelectric actuating platform,and its electromechanical characteristics are analyzed.Considering the hysteresis between the input voltage and output force and the dynamics equation between the output displacement and the output force of the piezoelectric actuator,the model structure of RDPI model cascaded second-order system is used to characterize the hysteresis nonlinearity of the piezoelectric actuating platform,and the MPSO algorithm is applied to determine the model parameters.Combined with the experimental verification of the model and two groups of comparative experiments,the effectiveness of the modeling method designed in this paper is proved.3)Designed the tracking control scheme of the piezoelectric actuating platform and completed the experimental verification.Regarding the hysteresis represented by the RDPI model as a bounded disturbance of the system,a closed-loop feedback adaptive backstepping control scheme is designed by combining the adaptive algorithm and the backstepping control algorithm,and the stability of the control system is proved.The effectiveness of the proposed control method has been verified by trajectory tracking experiments under different reference trajectories.An anti-windup compensator is introduced into the unsaturated control scheme to reduce the performance degradation of the controller caused by the input saturation of the piezoelectric actuator in practical application and the feasibility of the scheme is verified through experiments.This paper improves the actuating performance of the piezoelectric actuating platform through the modeling of hysteresis nonlinearity and control scheme design,which provides a theoretical basis for the subsequent application of piezoelectric actuators in micro-actuating systems of various fields.