File content as of revision 0:46cf63cba59a:

/*
* Parts of the code copied from PES lecture slides
*/

// include all necessary libraries
#include "mbed.h"
#include "QEI.h"

//intialize all pins
PwmOut motor1(D5);
PwmOut motor2(D6);
DigitalOut motor1Dir(D4); // direction of motor 1 (1 is ccw 0 is cw (looking at the shaft from the front))
DigitalOut motor2Dir(D7); // direction of motor 2 (1 is ccw 0 is cw (looking at the shaft from the front))
QEI motor1Encoder (D10,D11, NC, 624,QEI::X4_ENCODING);
QEI motor2Encoder (D12,D13, NC, 624,QEI::X4_ENCODING);
DigitalIn button1(D8); //button to move cw
DigitalIn button2(D9); //button to move ccw

//initialize variables
double angleIncrement = 0.036; // increment of angle when button pressed (1 is a whole rotation (360 degrees))

const double motor1KP=1.3; //Proportional gain of motor1 PI control
const double motor1KI=0.5; //Integral gain of motor1 PI control
const double motor1KD=0.5; // Differential gain of motor1 PID control

const double motor2KP=1.3; //Proportional gain of motor1 PI control
const double motor2KI=0.5; //Integral gain of motor1 PI control
const double motor2KD=0.5; // Differential gain of motor1 PID control

const double N=100; //LP filter coefficient
const double encoderToMotor= 0.000119047619047619; //proportion of the rotation of the motor to the rotation of the encoder
const double controllerTickerTime=0.01; //ticker frequency

double motor1ErrorInt=0; //error of motor1 for the integrating part of PI controller
double motor1ErrorDif=0; //error of motor1 for the integrating part of PI controller
double desiredPos1 =0; //desired position of motor1

double motor2ErrorInt=0; //error of motor1 for the integrating part of PI controller
double motor2ErrorDif=0; //error of motor1 for the integrating part of PI controller
double desiredPos2 =0; //desired position of motor1
//initialize ticker for checking and correcting the angle
Ticker myControllerTicker;


double PIDController(double error, const double Kp, const double Ki, const double Kd, double Ts, const double N,double &intError, double &DifError){
    const double a1 = -4/(N*Ts+2);
    const double a2 = -(N*Ts-2)/(N*Ts+2);
    const double b0 = (4*Kp + 4*Kd*N + 2*Ki*Ts + 2*Kp*N*Ts + Ki*N*pow(Ts,2))/(2*N*Ts + 4);
    const double b1 = (Ki*N*pow(Ts,2) - 4*Kp - 4*Kd*N)/(N*Ts + 2);
    const double b2 = (4*Kp + 4*Kd*N - 2*Ki*Ts - 2*Kp*N*Ts + Ki*N*pow(Ts,2))/(2*N*Ts + 4);

    double v = error - a1*intError - a2*DifError;
    double u = b0*v + b1*intError + b2*DifError;
    DifError = intError; intError = v;
    return u;
}


void motorButtonController(){
    double position1= encoderToMotor*motor1Encoder.getPulses();
    double posError1 = desiredPos1 - position1; 
    
    //change direction based on error sign
    if(PIDController( posError1, motor1KP, motor1KI,motor1KD, controllerTickerTime, N, motor1ErrorInt ,motor1ErrorDif)>0) {
        motor1Dir=0;
    } else {
        motor1Dir =1;
    }
    //set motor speed based on PI controller error
    motor1 = fabs(PIDController( posError1, motor1KP, motor1KI,motor1KD, controllerTickerTime, N, motor1ErrorInt ,motor1ErrorDif));
    
    double position2= encoderToMotor*motor2Encoder.getPulses();
    double posError2 = desiredPos2 - position2; 
    
    //change direction based on error sign
    if(PIDController( posError2, motor2KP, motor2KI,motor2KD, controllerTickerTime, N, motor2ErrorInt ,motor2ErrorDif)>0) {
        motor2Dir=0;
    } else {
        motor2Dir =1;
    }
    //set motor speed based on PI controller error
    motor2 = fabs(PIDController( posError2, motor2KP, motor2KI,motor2KD, controllerTickerTime, N, motor2ErrorInt ,motor2ErrorDif));

}

int main(){
    wait(2);
    myControllerTicker.attach(&motorButtonController, controllerTickerTime);
    while(1) {
        if(!button1) {
            desiredPos1+=angleIncrement;
            desiredPos2-=angleIncrement;
            wait(0.5f);
        }

        if(!button2) {
            desiredPos1-=angleIncrement;
            desiredPos2+=angleIncrement;
            wait(0.5f);
        }
    }
}