Research On Micro-angle Step Piezoelectric Motor Drive And Closed-loop Control System Based On FPGA

With the development of technology and science, the drive and control systemwith the property of high-resolution, high-precision, high stability and high repeatpositioning precision performance is extremely needy in the areas such as precisionmeasurement, nano science instruments, precision processing and assembly,semiconductor equipment and biological cell manipulation Also the development inpositioning and control of micro-displacement drive technology has provided thebasic technique for the super precision processing of micro-sized devices.Micro-angle step piezoelectric motor was designed based on the geometridmovement mechanism. FPGA was cybernetics core of driving control. The squarewave signals and the triangular wave signal generated by FPGA and integratingcircuit were control signals. The ModelSim simulation results show that the frequency,voltage, steps of four square wave output signals was stable.The RESM circular grating was used to detect angle signal in the form of digitaldifferential. The angle signal was sent into the closed loop control module of FPGAsystem, through incremental PID control algorithm, the error between the ideal valueand actual value was reduced. The Modelsim simulation results show that the errorvalue successive decreases, real-time simulation can meet the requirements of motorcontrol.The testing results of control system show that the output angle is reduced withincreasing of drive frequency and increased with increase of the driving voltage. Theerrors of closed-loop control system can be adjusted in a small range, systemresolution was0.11″. The minimum and maximum angular displacement of a stepwere12.57"and40.02", respectively measured under100V,40Hz and160V,20Hz,and both repeated positioning accuracy excellent at97%. The non-linearity was1.38%, the control system had wonderful linear. Closed-loop control can improve thedisplacement accuracy and stability, reduce positioning errors, and enhance reliability.The micro-angle piezoelectric motor can achieve360°circumference rotation andpositioning accuracy, stability high.