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/* Copyright 2012, Sebastian Reichel <sre@ring0.de>
* Copyright 2012, Ted Carancho
*
* Ported from AeroQuad
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
public class PID {
double P;
double I;
double D;
Timer timer;
double lastPosition;
double integratedError;
double windupGuard;
public void calibrate(double P, double I, double D) {
this.P = P;
this.I = I;
this.D = D;
}
public double update(double targetPosition, double currentPosition) {
/* delta time in seconds */
double deltaPIDTime = timer.ellapsed() / 1000000.0;
/* calculate error */
double error = targetPosition - currentPosition;
integratedError += error * deltaPIDTime;
integratedError = constrain(integratedError, -windupGuard, windupGuard);
double dTerm = D * (currentPosition - lastPosition) / (deltaPIDTime * 100);
lastPosition = currentPosition;
return P * error + I * integratedError + dTerm;
}
public void clear() {
integratedError = 0;
timer.start();
}
}
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