Ian Hua / PID

PID control library forked from Aaron Berk. Make sure to read articles from www.controlguru.com to properly understand how to instantiate the PID loop.

Fork of PID by Aaron Berk

PID.h@2:b55a16b5f05c, 2014-05-12 (annotated)

Committer:
pHysiX
Date:
Mon May 12 13:15:56 2014 +0000
Revision:
2:b55a16b5f05c
Parent:
1:ae1c6d19f4c6 
Added in ability to set Proportional Gain only

Who changed what in which revision?

UserRevisionLine numberNew contents of line
aberk 0:6e12a3e5af19 1 /**
aberk 0:6e12a3e5af19 2 * @author Aaron Berk
aberk 0:6e12a3e5af19 3 *
aberk 0:6e12a3e5af19 4 * @section LICENSE
aberk 0:6e12a3e5af19 5 *
aberk 0:6e12a3e5af19 6 * Copyright (c) 2010 ARM Limited
aberk 0:6e12a3e5af19 7 *
aberk 0:6e12a3e5af19 8 * Permission is hereby granted, free of charge, to any person obtaining a copy
aberk 0:6e12a3e5af19 9 * of this software and associated documentation files (the "Software"), to deal
aberk 0:6e12a3e5af19 10 * in the Software without restriction, including without limitation the rights
aberk 0:6e12a3e5af19 11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
aberk 0:6e12a3e5af19 12 * copies of the Software, and to permit persons to whom the Software is
aberk 0:6e12a3e5af19 13 * furnished to do so, subject to the following conditions:
aberk 0:6e12a3e5af19 14 *
aberk 0:6e12a3e5af19 15 * The above copyright notice and this permission notice shall be included in
aberk 0:6e12a3e5af19 16 * all copies or substantial portions of the Software.
aberk 0:6e12a3e5af19 17 *
aberk 0:6e12a3e5af19 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
aberk 0:6e12a3e5af19 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
aberk 0:6e12a3e5af19 20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
aberk 0:6e12a3e5af19 21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
aberk 0:6e12a3e5af19 22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
aberk 0:6e12a3e5af19 23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
aberk 0:6e12a3e5af19 24 * THE SOFTWARE.
aberk 0:6e12a3e5af19 25 *
aberk 0:6e12a3e5af19 26 * @section DESCRIPTION
aberk 0:6e12a3e5af19 27 *
aberk 0:6e12a3e5af19 28 * A PID controller is a widely used feedback controller commonly found in
aberk 0:6e12a3e5af19 29 * industry.
aberk 0:6e12a3e5af19 30 *
aberk 0:6e12a3e5af19 31 * This library is a port of Brett Beauregard's Arduino PID library:
aberk 0:6e12a3e5af19 32 *
aberk 0:6e12a3e5af19 33 * http://www.arduino.cc/playground/Code/PIDLibrary
aberk 0:6e12a3e5af19 34 *
aberk 0:6e12a3e5af19 35 * The wikipedia article on PID controllers is a good place to start on
aberk 0:6e12a3e5af19 36 * understanding how they work:
aberk 0:6e12a3e5af19 37 *
aberk 0:6e12a3e5af19 38 * http://en.wikipedia.org/wiki/PID_controller
aberk 0:6e12a3e5af19 39 *
aberk 0:6e12a3e5af19 40 * For a clear and elegant explanation of how to implement and tune a
aberk 0:6e12a3e5af19 41 * controller, the controlguru website by Douglas J. Cooper (who also happened
aberk 0:6e12a3e5af19 42 * to be Brett's controls professor) is an excellent reference:
aberk 0:6e12a3e5af19 43 *
aberk 0:6e12a3e5af19 44 * http://www.controlguru.com/
aberk 0:6e12a3e5af19 45 */
aberk 0:6e12a3e5af19 46
aberk 0:6e12a3e5af19 47 #ifndef PID_H
aberk 0:6e12a3e5af19 48 #define PID_H
aberk 0:6e12a3e5af19 49
aberk 0:6e12a3e5af19 50 /**
aberk 0:6e12a3e5af19 51 * Includes
aberk 0:6e12a3e5af19 52 */
aberk 0:6e12a3e5af19 53 #include "mbed.h"
aberk 0:6e12a3e5af19 54
aberk 0:6e12a3e5af19 55 /**
aberk 0:6e12a3e5af19 56 * Defines
aberk 0:6e12a3e5af19 57 */
aberk 0:6e12a3e5af19 58 #define MANUAL_MODE 0
aberk 0:6e12a3e5af19 59 #define AUTO_MODE 1
aberk 0:6e12a3e5af19 60
aberk 0:6e12a3e5af19 61 /**
aberk 0:6e12a3e5af19 62 * Proportional-integral-derivative controller.
aberk 0:6e12a3e5af19 63 */
aberk 0:6e12a3e5af19 64 class PID {
aberk 0:6e12a3e5af19 65
aberk 0:6e12a3e5af19 66 public:
aberk 0:6e12a3e5af19 67 /**
aberk 0:6e12a3e5af19 68 * Constructor.
aberk 0:6e12a3e5af19 69 *
aberk 0:6e12a3e5af19 70 * Sets default limits [0-3.3V], calculates tuning parameters, and sets
aberk 0:6e12a3e5af19 71 * manual mode with no bias.
aberk 0:6e12a3e5af19 72 *
aberk 0:6e12a3e5af19 73 * @param Kc - Tuning parameter
aberk 0:6e12a3e5af19 74 * @param tauI - Tuning parameter
aberk 0:6e12a3e5af19 75 * @param tauD - Tuning parameter
aberk 0:6e12a3e5af19 76 * @param interval PID calculation performed every interval seconds.
aberk 0:6e12a3e5af19 77 */
aberk 0:6e12a3e5af19 78 PID(float Kc, float tauI, float tauD, float interval);
aberk 0:6e12a3e5af19 79
aberk 0:6e12a3e5af19 80 /**
aberk 0:6e12a3e5af19 81 * Scale from inputs to 0-100%.
aberk 0:6e12a3e5af19 82 *
aberk 0:6e12a3e5af19 83 * @param InMin The real world value corresponding to 0%.
aberk 0:6e12a3e5af19 84 * @param InMax The real world value corresponding to 100%.
aberk 0:6e12a3e5af19 85 */
aberk 0:6e12a3e5af19 86 void setInputLimits(float inMin , float inMax);
aberk 0:6e12a3e5af19 87
aberk 0:6e12a3e5af19 88 /**
aberk 0:6e12a3e5af19 89 * Scale from outputs to 0-100%.
aberk 0:6e12a3e5af19 90 *
aberk 0:6e12a3e5af19 91 * @param outMin The real world value corresponding to 0%.
aberk 0:6e12a3e5af19 92 * @param outMax The real world value corresponding to 100%.
aberk 0:6e12a3e5af19 93 */
aberk 0:6e12a3e5af19 94 void setOutputLimits(float outMin, float outMax);
aberk 0:6e12a3e5af19 95
aberk 0:6e12a3e5af19 96 /**
aberk 0:6e12a3e5af19 97 * Calculate PID constants.
aberk 0:6e12a3e5af19 98 *
aberk 0:6e12a3e5af19 99 * Allows parameters to be changed on the fly without ruining calculations.
aberk 0:6e12a3e5af19 100 *
aberk 0:6e12a3e5af19 101 * @param Kc - Tuning parameter
aberk 0:6e12a3e5af19 102 * @param tauI - Tuning parameter
aberk 0:6e12a3e5af19 103 * @param tauD - Tuning parameter
aberk 0:6e12a3e5af19 104 */
aberk 0:6e12a3e5af19 105 void setTunings(float Kc, float tauI, float tauD);
pHysiX 2:b55a16b5f05c 106
pHysiX 2:b55a16b5f05c 107 /**
pHysiX 2:b55a16b5f05c 108 * Set Proportional Gain
pHysiX 2:b55a16b5f05c 109 *
pHysiX 2:b55a16b5f05c 110 * Change Proportional Gain only
pHysiX 2:b55a16b5f05c 111 *
pHysiX 2:b55a16b5f05c 112 * @param Kc - Proportional gain
pHysiX 2:b55a16b5f05c 113 */
pHysiX 2:b55a16b5f05c 114 void setKP(float KP);
aberk 0:6e12a3e5af19 115
aberk 0:6e12a3e5af19 116 /**
aberk 0:6e12a3e5af19 117 * Reinitializes controller internals. Automatically
aberk 0:6e12a3e5af19 118 * called on a manual to auto transition.
aberk 0:6e12a3e5af19 119 */
aberk 0:6e12a3e5af19 120 void reset(void);
aberk 0:6e12a3e5af19 121
aberk 0:6e12a3e5af19 122 /**
aberk 0:6e12a3e5af19 123 * Set PID to manual or auto mode.
aberk 0:6e12a3e5af19 124 *
aberk 0:6e12a3e5af19 125 * @param mode 0 -> Manual
aberk 0:6e12a3e5af19 126 * Non-zero -> Auto
aberk 0:6e12a3e5af19 127 */
aberk 0:6e12a3e5af19 128 void setMode(int mode);
aberk 0:6e12a3e5af19 129
aberk 0:6e12a3e5af19 130 /**
aberk 0:6e12a3e5af19 131 * Set how fast the PID loop is run.
aberk 0:6e12a3e5af19 132 *
aberk 0:6e12a3e5af19 133 * @param interval PID calculation peformed every interval seconds.
aberk 0:6e12a3e5af19 134 */
aberk 0:6e12a3e5af19 135 void setInterval(float interval);
aberk 0:6e12a3e5af19 136
aberk 0:6e12a3e5af19 137 /**
aberk 0:6e12a3e5af19 138 * Set the set point.
aberk 0:6e12a3e5af19 139 *
aberk 0:6e12a3e5af19 140 * @param sp The set point as a real world value.
aberk 0:6e12a3e5af19 141 */
aberk 0:6e12a3e5af19 142 void setSetPoint(float sp);
aberk 0:6e12a3e5af19 143
aberk 0:6e12a3e5af19 144 /**
aberk 0:6e12a3e5af19 145 * Set the process value.
aberk 0:6e12a3e5af19 146 *
aberk 0:6e12a3e5af19 147 * @param pv The process value as a real world value.
aberk 0:6e12a3e5af19 148 */
aberk 0:6e12a3e5af19 149 void setProcessValue(float pv);
aberk 0:6e12a3e5af19 150
aberk 0:6e12a3e5af19 151 /**
aberk 0:6e12a3e5af19 152 * Set the bias.
aberk 0:6e12a3e5af19 153 *
aberk 0:6e12a3e5af19 154 * @param bias The bias for the controller output.
aberk 0:6e12a3e5af19 155 */
aberk 0:6e12a3e5af19 156 void setBias(float bias);
aberk 0:6e12a3e5af19 157
aberk 0:6e12a3e5af19 158 /**
aberk 0:6e12a3e5af19 159 * PID calculation.
aberk 0:6e12a3e5af19 160 *
aberk 0:6e12a3e5af19 161 * @return The controller output as a float between outMin and outMax.
aberk 0:6e12a3e5af19 162 */
aberk 0:6e12a3e5af19 163 float compute(void);
aberk 0:6e12a3e5af19 164
aberk 0:6e12a3e5af19 165 //Getters.
aberk 0:6e12a3e5af19 166 float getInMin();
aberk 0:6e12a3e5af19 167 float getInMax();
aberk 0:6e12a3e5af19 168 float getOutMin();
aberk 0:6e12a3e5af19 169 float getOutMax();
aberk 0:6e12a3e5af19 170 float getInterval();
aberk 0:6e12a3e5af19 171 float getPParam();
aberk 0:6e12a3e5af19 172 float getIParam();
aberk 0:6e12a3e5af19 173 float getDParam();
aberk 0:6e12a3e5af19 174
aberk 0:6e12a3e5af19 175 private:
aberk 0:6e12a3e5af19 176 bool usingFeedForward;
aberk 0:6e12a3e5af19 177 bool inAuto;
aberk 0:6e12a3e5af19 178
aberk 0:6e12a3e5af19 179 //Actual tuning parameters used in PID calculation.
aberk 0:6e12a3e5af19 180 float Kc_;
aberk 0:6e12a3e5af19 181 float tauR_;
aberk 0:6e12a3e5af19 182 float tauD_;
aberk 0:6e12a3e5af19 183
aberk 0:6e12a3e5af19 184 //Raw tuning parameters.
aberk 0:6e12a3e5af19 185 float pParam_;
aberk 0:6e12a3e5af19 186 float iParam_;
aberk 0:6e12a3e5af19 187 float dParam_;
aberk 0:6e12a3e5af19 188
aberk 0:6e12a3e5af19 189 //The point we want to reach.
aberk 0:6e12a3e5af19 190 float setPoint_;
aberk 0:6e12a3e5af19 191 //The thing we measure.
aberk 0:6e12a3e5af19 192 float processVariable_;
aberk 0:6e12a3e5af19 193 float prevProcessVariable_;
aberk 0:6e12a3e5af19 194 //The output that affects the process variable.
aberk 0:6e12a3e5af19 195 float controllerOutput_;
aberk 0:6e12a3e5af19 196 float prevControllerOutput_;
aberk 0:6e12a3e5af19 197
aberk 0:6e12a3e5af19 198 //We work in % for calculations so these will scale from
aberk 0:6e12a3e5af19 199 //real world values to 0-100% and back again.
aberk 0:6e12a3e5af19 200 float inMin_;
aberk 0:6e12a3e5af19 201 float inMax_;
aberk 0:6e12a3e5af19 202 float inSpan_;
aberk 0:6e12a3e5af19 203 float outMin_;
aberk 0:6e12a3e5af19 204 float outMax_;
aberk 0:6e12a3e5af19 205 float outSpan_;
aberk 0:6e12a3e5af19 206
aberk 0:6e12a3e5af19 207 //The accumulated error, i.e. integral.
aberk 0:6e12a3e5af19 208 float accError_;
aberk 0:6e12a3e5af19 209 //The controller output bias.
aberk 0:6e12a3e5af19 210 float bias_;
aberk 0:6e12a3e5af19 211
aberk 0:6e12a3e5af19 212 //The interval between samples.
aberk 0:6e12a3e5af19 213 float tSample_;
aberk 0:6e12a3e5af19 214
aberk 0:6e12a3e5af19 215 //Controller output as a real world value.
aberk 0:6e12a3e5af19 216 volatile float realOutput_;
aberk 0:6e12a3e5af19 217 };
aberk 0:6e12a3e5af19 218
aberk 0:6e12a3e5af19 219 #endif /* PID_H */