DC Motor Speed PID Control with Arduino

It is a new MechLab for NCKU ME next semester, a PID controller!
Hardware:

• Arduino Mega2560
• Motor Shield: Dual H-brigde VNH2SP30
• Due to there is no lib of this shield, I modify the dual-vnh5019 Lib to fit the goal
• Github: https://github.com/kvzhao/DualVNH2SH30MotorShield

• DC Motor - IG42
• I also write a C++ wrapper for this motor, utilizing Encoder lib(also a little modify for constructor) and VNH2SP30 lib
• Github: https://github.com/kvzhao/DCMotorIG42

Source Code on Github: https://github.com/kvzhao/ME-PIDLab

The crucial part of the PID code is listed below

void loop()
{
    // Run a period to estimate more precise speed
    Motor.Tick();
    // Run for one Second
    delay(SamplingTime);
    Motor.Tock();

    // Read rotation speed from Encoder
    Input = Motor.getSpeedRPS();

    // PID Compute
    PID_Controller.Compute();
    if ((Output-prevOutput) >= oscGap) {
      //Output = prevOutput;
    }
    Motor.setSpeed(Output);
    prevOutput = Output;
    // Show Data
    /*
    Serial.print("Input: ");
    Serial.println(Input);
    Serial.print("Setpoint: "); 
    Serial.println(Setpoint);    
    Serial.print("Error: ");
    Serial.println(error);
    Serial.print("Output: "); 
    Serial.println(Output);*/
    Serial.println(error);
    // wait a little while
    delay(5);
}

My first test result (with KP=98, KI=8, PD=5)

There is almost no steady state error, however overshoot happens.

Next step is to tune the parameters and control the motor smoothly!

Some useful references

• http://www.robotroom.com/PWM5.html
• http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-012-driving-vibration-motors-with-pwm
• http://lancet.mit.edu/motors/motors3.html
• http://mechatronics.mech.northwestern.edu/design_ref/actuators/motor_theory.html
• http://www.roadtocreate.com/?tag=vnh2sp30
• http://www.pololu.com/product/537