PID.h

00001 /**
00002  * @author Aaron Berk
00003  *
00004  * @section LICENSE
00005  *
00006  * Copyright (c) 2010 ARM Limited
00007  *
00008  * Permission is hereby granted, free of charge, to any person obtaining a copy
00009  * of this software and associated documentation files (the "Software"), to deal
00010  * in the Software without restriction, including without limitation the rights
00011  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00012  * copies of the Software, and to permit persons to whom the Software is
00013  * furnished to do so, subject to the following conditions:
00014  *
00015  * The above copyright notice and this permission notice shall be included in
00016  * all copies or substantial portions of the Software.
00017  *
00018  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00019  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00020  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00021  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00022  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00023  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00024  * THE SOFTWARE.
00025  *
00026  * @section DESCRIPTION
00027  * 
00028  * A PID controller is a widely used feedback controller commonly found in
00029  * industry.
00030  *
00031  * This library is a port of Brett Beauregard's Arduino PID library:
00032  *
00033  *  http://www.arduino.cc/playground/Code/PIDLibrary
00034  *
00035  * The wikipedia article on PID controllers is a good place to start on
00036  * understanding how they work:
00037  *
00038  *  http://en.wikipedia.org/wiki/PID_controller
00039  *
00040  * For a clear and elegant explanation of how to implement and tune a
00041  * controller, the controlguru website by Douglas J. Cooper (who also happened
00042  * to be Brett's controls professor) is an excellent reference:
00043  *
00044  *  http://www.controlguru.com/
00045  */
00046 
00047 // Modified by K.Arai/JH1PJL on June 15th, 2016
00048 
00049 #ifndef PID_H
00050 #define PID_H
00051 
00052 /**
00053  * Includes
00054  */
00055 #include "mbed.h"
00056 
00057 /**
00058  * Defines
00059  */
00060 #define MANUAL_MODE 0
00061 #define AUTO_MODE   1
00062 
00063 /**
00064  * Proportional-integral-derivative controller.
00065  */
00066 class PID {
00067 
00068 public:
00069 
00070     /**
00071      * Constructor.
00072      *
00073      * Sets default limits [0-3.3V], calculates tuning parameters, and sets
00074      * manual mode with no bias.
00075      *
00076      * @param Kc - Tuning parameter
00077      * @param tauI - Tuning parameter
00078      * @param tauD - Tuning parameter
00079      * @param interval PID calculation performed every interval seconds.
00080      */
00081     PID(double Kc, double tauI, double tauD, double interval);
00082 
00083     /**
00084      * Scale from inputs to 0-100%.
00085      *
00086      * @param InMin The real world value corresponding to 0%.
00087      * @param InMax The real world value corresponding to 100%.
00088      */
00089     void setInputLimits(double inMin , double inMax);
00090 
00091     /**
00092      * Scale from outputs to 0-100%.
00093      *
00094      * @param outMin The real world value corresponding to 0%.
00095      * @param outMax The real world value corresponding to 100%.
00096      */
00097     void setOutputLimits(double outMin, double outMax);
00098 
00099     /**
00100      * Calculate PID constants.
00101      *
00102      * Allows parameters to be changed on the fly without ruining calculations.
00103      *
00104      * @param Kc - Tuning parameter
00105      * @param tauI - Tuning parameter
00106      * @param tauD - Tuning parameter
00107      */
00108     void setTunings(double Kc, double tauI, double tauD);
00109 
00110     /**
00111      * Reinitializes controller internals. Automatically
00112      * called on a manual to auto transition.
00113      */
00114     void reset(void);
00115     
00116     /**
00117      * Set PID to manual or auto mode.
00118      *
00119      * @param mode        0 -> Manual
00120      *             Non-zero -> Auto
00121      */
00122     void setMode(int mode);
00123     
00124     /**
00125      * Set how fast the PID loop is run.
00126      *
00127      * @param interval PID calculation peformed every interval seconds.
00128      */
00129     void setInterval(double interval);
00130     
00131     /**
00132      * Set the set point.
00133      *
00134      * @param sp The set point as a real world value.
00135      */
00136     void setSetPoint(double sp);
00137     
00138     /**
00139      * Set the process value.
00140      *
00141      * @param pv The process value as a real world value.
00142      */
00143     void setProcessValue(double pv);
00144     
00145     /**
00146      * Set the bias.
00147      *
00148      * @param bias The bias for the controller output.
00149      */
00150     void setBias(double bias);
00151 
00152     /**
00153      * PID calculation.
00154      *
00155      * @return The controller output as a double between outMin and outMax.
00156      */
00157     double compute(void);
00158 
00159     //Getters.
00160     double getInMin();
00161     double getInMax();
00162     double getOutMin();
00163     double getOutMax();
00164     double getInterval();
00165     double getPParam();
00166     double getIParam();
00167     double getDParam();
00168 
00169 private:
00170 
00171     bool usingFeedForward;
00172     bool inAuto;
00173 
00174     //Actual tuning parameters used in PID calculation.
00175     double Kc_;
00176     double tauR_;
00177     double tauD_;
00178     
00179     //Raw tuning parameters.
00180     double pParam_;
00181     double iParam_;
00182     double dParam_;
00183     
00184     //The point we want to reach.
00185     double setPoint_;         
00186     //The thing we measure.
00187     double processVariable_;  
00188     double prevProcessVariable_;
00189     //The output that affects the process variable.
00190     double controllerOutput_; 
00191     double prevControllerOutput_;
00192 
00193     //We work in % for calculations so these will scale from
00194     //real world values to 0-100% and back again.
00195     double inMin_;
00196     double inMax_;
00197     double inSpan_;
00198     double outMin_;
00199     double outMax_;
00200     double outSpan_;
00201 
00202     //The accumulated error, i.e. integral.
00203     double accError_;
00204     //The controller output bias.
00205     double bias_;
00206 
00207     //The interval between samples.
00208     double tSample_;          
00209 
00210     //Controller output as a real world value.
00211     volatile double realOutput_;
00212 
00213 };
00214 
00215 #endif /* PID_H */