Modeling And Compensation Method Piezoelectric Actuator Based On Hammerstein Model

Piezoceramic actuators,as the main actuators of fast tilt mirrors,are the guarantee that space laser communication can establish a stable communication link.Piezoceramic actuators have the advantages of high rigidity,high displacement resolution,and large output force.Compared with other actuators such as voice coil motors,they are more suitable for precise tracking control of light beams.Although piezoelectric ceramic actuators have many advantages,it is undeniable that the inherent asymmetric hysteresis characteristics and rate-dependent characteristics limit the application of piezoelectric ceramic actuators.The so-called asymmetric hysteresis characteristic means that the input voltage and the output displacement of the piezoelectric ceramic actuator exhibit a non-symmetrical hysteresis relationship,and the size and shape of the hysteresis loop will change with the frequency of the input signal.In order to compensate for the asymmetric hysteresis and rate-dependent characteristics of piezoelectric ceramic actuators,this paper describes the asymmetric hysteresis and rate-dependent characteristics of piezoelectric ceramic actuators based on the Hammerstein model.First,an asymmetric hysteresis model is established in which a symmetric hysteresis model is connected in series with a nonlinear compensation function.Further,the corresponding model identification method is proposed.First,the symmetric hysteresis model is used to describe the actual asymmetric hysteresis phenomenon.At this time,a large model error will be introduced,and then the output of the symmetric hysteresis model is corrected by the memoryless nonlinear compensation function to achieve The purpose of reducing model errors.Both the symmetrical hysteresis model and the nonlinear compensation function are described by polynomials,which has the advantages of a simple identification method and fewer identification parameters.In order to verify the effectiveness of the proposed model,an experimental platform with piezoelectric ceramic micro-displacement mechanism as the research object was built.In order to compensate for the asymmetric hysteresis characteristics,a method for obtaining the inverse model of the asymmetric hysteresis model is given.Using the obtained inverse hysteresis model to compensate the asymmetric hysteresis characteristics of the piezoelectric ceramic actuator can significantly reduce the hysteresis nonlinearity.influences.Secondly,the dynamic transfer function of the piezoelectric ceramic actuator is measured based on the frequency method,and then the velocity-dependent characteristics of the piezoelectric ceramic actuator are described.The established asymmetric hysteresis model is used in series with the dynamic transfer function G(s)to form a complete Hammerstein model to describe the asymmetric hysteresis and velocity-dependent characteristics of piezoelectric ceramic actuators.Finally,the composite control scheme is used to verify that the Hammerstein model has a certain dynamic signal tracking ability.In this paper,the asymmetric hysteresis and rate-dependent characteristics of piezoelectric ceramic actuators are studied,which lays a theoretical foundation for the rapid and high-precision positioning of fast tilt mirrors in space laser communication systems.