Double Reading Heads Self-Calibration And Active Disturbance Rejection Control Of The Linear Grating Servo System

At present,high-precision measurement methods such as laser interferometer are required for calibration of grating ruler.The motion platform is generally adopted in the traditional PID control mode.This paper studies the calibration of the linear grating and the control of the servo system,introduces the self-calibration mode by double reading heads and active disturbance rejection control(ADRC)of the system.This paper analyzes the measurement error of linear grating measuring system,and analyzes the calibration mode of nonlinear error according to the nature of the error.This paper introduces the principle of self-calibration mode by double reading heads,verify the feasibility of this method and analyzes the influence of measurement noise by simulation.This paper designed ADRC for linear motion platform,the algorithm uses the classic structure of ADRC.Extended state observer receives system direct input(finally form the integral series system).State errors feedback uses nonlinear the most rapid control function.By simulation,this paper compares the result of step response and constant disturbance with ADRC and classic PID,analyzes the influence of the parameters of ADRC on the result.This paper set up one dimension linear precision platform with linear grating as feedback device,linear coreless motor as the drive,servo system including driver,controller,etc.A LabVIEW program based on NI CompactRIO is written,which can measure and record of double reading heads,realize PID and ADRC,and add simulation disturbance.This paper carry out the experiment of self-calibration by double-reading heads and compare the result by laser interferometer.The experiment shows that the calibration method is effective.This paper carry out the ADRC control of the servo system showing that the disturbance can be suppressed effectively.