File content as of revision 1:117e0c36eb22:

/**
* Includes
*/
#include "PID.h"

PID::PID(float Kc, float tauI, float tauD, float interval) {

    usingFeedForward = false;
    inAuto = false;

    //Default the limits to the full range of I/O.
    //Make sure to set these to more appropriate limits for your application.
    setInputLimits(0.0, 100.0);
    setOutputLimits(0.0,100.0);

    tSample_ = interval;

    setTunings(Kc, tauI, tauD);

    setPoint_ = 0.0;
    processVariable_ = 0.0;
    prevProcessVariable_ = 0.0;
    controllerOutput_ = 0.0;
    prevControllerOutput_ = 0.0;

    accError_ = 0.0;
    bias_ = 0.0;

    realOutput_ = 0.0;

}

void PID::setInputLimits(float inMin, float inMax) {

    //Make sure we haven't been given impossible values.
    if (inMin >= inMax) {
        return;
    }

    //Rescale the working variables to reflect the changes.
    prevProcessVariable_ *= (inMax - inMin) / inSpan_;
    accError_ *= (inMax - inMin) / inSpan_;

    //Make sure the working variables are within the new limits.
    if (prevProcessVariable_ > 1) {
        prevProcessVariable_ = 1;
    }
    else if (prevProcessVariable_ < 0) {
        prevProcessVariable_ = 0;
    }

    inMin_ = inMin;
    inMax_ = inMax;
    inSpan_ = inMax - inMin;

}

void PID::setOutputLimits(float outMin, float outMax) {

    //Make sure we haven't been given impossible values.
    if (outMin >= outMax) {
        return;
    }

    //Rescale the working variables to reflect the changes.
    prevControllerOutput_ *= (outMax - outMin) / outSpan_;

    //Make sure the working variables are within the new limits.
    if (prevControllerOutput_ > 1) {
        prevControllerOutput_ = 1;
    }
    else if (prevControllerOutput_ < 0) {
        prevControllerOutput_ = 0;
    }

    outMin_ = outMin;
    outMax_ = outMax;
    outSpan_ = outMax - outMin;

}

void PID::setTunings(float Kc, float tauI, float tauD) {

    //Verify that the tunings make sense.
    if (Kc == 0.0 || tauI < 0.0 || tauD < 0.0) {
        return;
    }

    //Store raw values to hand back to user on request.
    pParam_ = Kc;
    iParam_ = tauI;
    dParam_ = tauD;

    float tempTauR;

    if (tauI == 0.0) {
        tempTauR = 0.0;
    }
    else {
        tempTauR = (1.0 / tauI) * tSample_;
    }

    //For "bumpless transfer" we need to rescale the accumulated error.
    //if (inAuto) {
        //if (tempTauR == 0.0) {
            //accError_ = 0.0;
        //}
        //else {
            accError_ *= (Kc_ * tauR_) / (Kc * tempTauR);
        //}
    //}

    Kc_ = Kc;
    tauR_ = tempTauR;
    tauD_ = tauD / tSample_;

}

void PID::reset(void) {

    float scaledBias = 0.0;

    if (usingFeedForward) {
        scaledBias = (bias_ - outMin_) / outSpan_;
    }
    else {
        scaledBias = (realOutput_ - outMin_) / outSpan_;
    }

    prevControllerOutput_ = scaledBias;
    prevProcessVariable_ = (processVariable_ - inMin_) / inSpan_;

    //Clear any error in the integral.
    accError_ = 0;

}

void PID::setMode(int mode) {

    //We were in manual, and we just got set to auto.
    //Reset the controller internals.
    if (mode != 0 && !inAuto) {
        reset();
    }

    inAuto = (mode != 0);

}

void PID::setInterval(float interval) {

    if (interval > 0) {
        //Convert the time-based tunings to reflect this change.
        tauR_ *= (interval / tSample_);
        accError_ *= (tSample_ / interval);
        tauD_ *= (interval / tSample_);
        tSample_ = interval;
    }

}

void PID::setSetPoint(float sp) {

    setPoint_ = sp;

}

void PID::setProcessValue(float pv) {

    processVariable_ = pv;

}

void PID::setBias(float bias){

    bias_ = bias;
    usingFeedForward = 1;

}

float PID::compute(float pv,  float sp) {

    //enregistrer variables dans var interne
    processVariable_ = pv; //ce que l'on mesure
    setPoint_ = sp;  // ce que l'on veut atteindre

    //Pull in the input and setpoint, and scale them into percent span.
    float scaledPV = (processVariable_ - inMin_) / inSpan_;

    if (scaledPV > 1.0) {
        scaledPV = 1.0;
    }
    else if (scaledPV < 0.0) {
        scaledPV = 0.0;
    }

    float scaledSP = (setPoint_ - inMin_) / inSpan_;
    if (scaledSP > 1.0) {
        scaledSP = 1;
    }
    else if (scaledSP < 0.0) {
        scaledSP = 0;
    }

    float error = scaledSP - scaledPV;

    //Check and see if the output is pegged at a limit and only
    //integrate if it is not. This is to prevent reset-windup.
    if (!(prevControllerOutput_ >= 1 && error > 0) && !(prevControllerOutput_ <= 0 && error < 0)) {
        accError_ += error;
    }

    //Compute the current slope of the input signal.
    float dMeas = (scaledPV - prevProcessVariable_) / tSample_;
    //float dMeas = (scaledPV - prevProcessVariable_);

    float scaledBias = 0.0;

    if (usingFeedForward) {
        scaledBias = (bias_ - outMin_) / outSpan_;
    }

    //Perform the PID calculation.
    controllerOutput_ = scaledBias + Kc_ * (error + (tauR_ * accError_) - (tauD_ * dMeas));
    //controllerOutput_ = Kc_ * error + tauR_ * accError_ + tauD_ * dMeas;

    //Make sure the computed output is within output constraints.
    if (controllerOutput_ < 0.0) {
        controllerOutput_ = 0.0;
    }
    else if (controllerOutput_ > 1.0) {
        controllerOutput_ = 1.0;
    }

    //Remember this output for the windup check next time.
    prevControllerOutput_ = controllerOutput_;
    //Remember the input for the derivative calculation next time.
    prevProcessVariable_ = scaledPV;

    //Scale the output from percent span back out to a real world number.
    return ((controllerOutput_ * outSpan_) + outMin_);

}

float PID::getInMin() {

    return inMin_;

}

float PID::getInMax() {

    return inMax_;

}

float PID::getOutMin() {

    return outMin_;

}

float PID::getOutMax() {

    return outMax_;

}

float PID::getInterval() {

    return tSample_;

}

float PID::getPParam() {

    return pParam_;

}

float PID::getIParam() {

    return iParam_;

}

float PID::getDParam() {

    return dParam_;

}