PID controller of servo system in real time linux Environment

Abstract

This work presents an implementation of a digital PID (Proportional + Integral + Derivative) controller algorithm in real-Time Linux environment. PID controllers are well known and have a wide range of applications in automatic control of systems. such as servomotors and temperature control etc. PID values are dependent on the sampling rate at which system output is read and the new value for system input generated. In order to achieve the desired performance the system output (axis position) is feed-back to the PID controller which generated the system input (motor voltage), in a closed loop. The Real-Time system is the accurate system which gives lowest latency. Through this real real-time the temperature control unit is controlled. The PID controller computes the error of the temperature control circuit between the desired system output (reference) and the actual system output. Then, the system input, which is the PID controller output, is generated as weighted sum of the error, its integral and derivative. The weighting coefficients are known as controller gains and referred as Kp, Ki, and Kd. The values of the controller gains determine the performance of the closed loop system and even its stability. The data acquisition card AX5411 receives the data from the computer to control the temperature controller and retrieve the data and send it to computer again from the output as a feed back element simultaneously.