Research On The Velocity Measurement Method Of Incremental Encoder Based On Kalman Filter

Incremental photoelectric encoders are widely used in servo control systems due to their small size,strong anti-interference,high resolution,stable output,and low cost.For servo motor control system,the accuracy of the speed measurement affects the stability and accuracy of the motor control directly.Based on summarizing the research status of encoder speed measurement at home and abroad,to solve the problems that the common speed measurement algorithms,such as the "M" method and "T" method,cannot adapt to the entire speed range and the traditional "M/T" method has poor real-time performance when measuring low velocity,in this paper,a new variable "M/T"high-accuracy and real-time dynamic speed measurement method based on Kalman filtering is proposed.Kalman filtering is the most optimized autoregressive data processing algorithm.The kalman filter can effectively filter out the noise and interference in the process of speed measurement and estimate the present velocity value based on the state of the last time step.Then the optimum method is selected the optimal sampling period or pulse number at the next moment by analyzing the estimated value range.Combining the measured value and the predicted value at the present moment,the high-precision optimal rotational speed estimation value can be obtained.The method has been implemented on the STM32F303RET6 digital signal controller and measured the real-time speed of the high-speed rotary table manufactured by CKD Corporation of Japan.Finally,the one-dimensional rotational speed measurement algorithm was extended to three-dimensional measurement of displacement,angular velocity and angular acceleration,and corresponding simulation analysis was performed.Simulations and experimental platform test results show that:the new variable"M/T" speed measurement method based on Kalman filtering can give a relatively real-time and accurate speed value in the whole speed section of the turntable,and can suppress and eliminate the effects of quantization error in sampling time interval.Thus,the new speed measurement method is of great pratical significant to improve the accuracy of encoder dynamic speed measurement.