Driving Control And Research Of High Precision Piezoelectric Ceramic Displacement Platform

Piezoelectric ceramic displacement platform as a kind of high precision nano positioning system,because of its high positioning accuracy,no transmission,small size and fast response speed and other advantages,has been widely used in optics,optoelectronics,biological detection,aerospace,precision manufacturing and other fields,and has become an important symbol to measure the national scientific and technological strength and economic power.The hysteresis and other characteristics of piezoelectric ceramics seriously affect the output accuracy of the platform,and the excellent driving controller can make up for the shortcomings of the platform itself,so the research on the driving controller of the platform is particularly important.Therefore,this paper carries out research on the driving control of the piezoelectric ceramic displacement platform.(1)The characteristics of piezoelectric ceramics and the structure of the displacement platform are analyzed,and then the hysteresis characteristics of piezoelectric ceramics are described.Based on the traditional Prandtl-Ishlinskii model,a piecewise P-I model is proposed to decompose the hysteresis behavior into a rising stage and a falling stage.The weights and thresholds of different stages are selected.To achieve the purpose of accurate fitting,the traditional P-I model can not accurately describe the hysteresis characteristics due to the odd symmetry of the shortcoming,and then use MATLAB to verify,the final comparison,the fitting error rate reduced from 3.5% to 0.7%.(2)The power supply and driver of the piezoelectric ceramic displacement platform are designed.The power supply adopts a flyback DC-DC converter based on Buck-Boost topology,and adopts a 4-stage parallel structure to convert the input 24 V DC voltage into the DC voltage required by each part of the displacement platform.In the driver part,the error amplifier circuit is used.On this basis,the two-stage amplifier structure is designed,with the unit gain of the front stage and ten times the gain of the rear stage,which can ensure that the driver circuit has a high precision calculation output value.The power amplifier part adopts complementary push-free circuit structure,and uses MOS tubes of different polarity to output voltage,so as to achieve the purpose of driving the platform.The hardware circuit is generated and its feasibility is verified by experiments.(3)The control part of the piezoelectric ceramic displacement platform is designed.The piecewise P-I hysteresis inverse model is used as the feedforward compensation item,and the closed-loop control part and the detection part of the controller are composed by the analog circuit.In the closed-loop control part,a series PI controller is adopted.In order to obtain higher control accuracy,a conversion rate limiting circuit,a double T notch filter circuit,and a zero drift compensation circuit are designed to form a feedback control circuit.In the detection loop,the resistance strain gauge sensor is used to detect the displacement error,Wheatstone bridge is used to detect the displacement difference,and the error signal is amplified 100 times by the instrument amplifier.The adjustable low-pass filter circuit is designed to provide high quality output signal.In summary,a composite controller is formed for the control part of the piezoelectric ceramic displacement platform,and its feasibility is verified by experiments.(4)The drive control part of the piezoelectric ceramic displacement platform was verified experimentally under the open-loop condition.The experimental results show that the output magnification is 10 times,the output stability is 0.228%,the long-term drift value is 12 m V,and the voltage ripple noise is less than 16 m V.The experimental results show that the accuracy of the platform under control is 0.045956μm,the precision of repeated positioning is 0.048032μm,the hysteresis error is 0.005%,the compensation linearity under the composite controller is0.86%,and the root mean square error of the dynamic response of the composite controller is0.066.The results show that the designed drive control system has good output characteristics and control precision.