Kenji Arai / PID

change float to double

Fork of PID by Aaron Berk

PID.cpp@1:ca4077d72c94, 2016-11-23 (annotated)

Committer:
kenjiArai
Date:
Wed Nov 23 07:13:07 2016 +0000
Revision:
1:ca4077d72c94
Parent:
0:6e12a3e5af19 
Change float to double

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
kenjiArai 1:ca4077d72c94 47 // Modified by K.Arai/JH1PJL on June 15th, 2016
kenjiArai 1:ca4077d72c94 48
aberk 0:6e12a3e5af19 49 /**
aberk 0:6e12a3e5af19 50 * Includes
aberk 0:6e12a3e5af19 51 */
aberk 0:6e12a3e5af19 52 #include "PID.h"
aberk 0:6e12a3e5af19 53
kenjiArai 1:ca4077d72c94 54 PID::PID(double Kc, double tauI, double tauD, double interval) {
aberk 0:6e12a3e5af19 55
aberk 0:6e12a3e5af19 56 usingFeedForward = false;
aberk 0:6e12a3e5af19 57 inAuto = false;
aberk 0:6e12a3e5af19 58
aberk 0:6e12a3e5af19 59 //Default the limits to the full range of I/O: 3.3V
aberk 0:6e12a3e5af19 60 //Make sure to set these to more appropriate limits for
aberk 0:6e12a3e5af19 61 //your application.
aberk 0:6e12a3e5af19 62 setInputLimits(0.0, 3.3);
aberk 0:6e12a3e5af19 63 setOutputLimits(0.0, 3.3);
aberk 0:6e12a3e5af19 64
aberk 0:6e12a3e5af19 65 tSample_ = interval;
aberk 0:6e12a3e5af19 66
aberk 0:6e12a3e5af19 67 setTunings(Kc, tauI, tauD);
aberk 0:6e12a3e5af19 68
aberk 0:6e12a3e5af19 69 setPoint_ = 0.0;
aberk 0:6e12a3e5af19 70 processVariable_ = 0.0;
aberk 0:6e12a3e5af19 71 prevProcessVariable_ = 0.0;
aberk 0:6e12a3e5af19 72 controllerOutput_ = 0.0;
aberk 0:6e12a3e5af19 73 prevControllerOutput_ = 0.0;
aberk 0:6e12a3e5af19 74
aberk 0:6e12a3e5af19 75 accError_ = 0.0;
aberk 0:6e12a3e5af19 76 bias_ = 0.0;
aberk 0:6e12a3e5af19 77
aberk 0:6e12a3e5af19 78 realOutput_ = 0.0;
aberk 0:6e12a3e5af19 79
aberk 0:6e12a3e5af19 80 }
aberk 0:6e12a3e5af19 81
kenjiArai 1:ca4077d72c94 82 void PID::setInputLimits(double inMin, double inMax) {
aberk 0:6e12a3e5af19 83
aberk 0:6e12a3e5af19 84 //Make sure we haven't been given impossible values.
aberk 0:6e12a3e5af19 85 if (inMin >= inMax) {
aberk 0:6e12a3e5af19 86 return;
aberk 0:6e12a3e5af19 87 }
aberk 0:6e12a3e5af19 88
aberk 0:6e12a3e5af19 89 //Rescale the working variables to reflect the changes.
aberk 0:6e12a3e5af19 90 prevProcessVariable_ *= (inMax - inMin) / inSpan_;
aberk 0:6e12a3e5af19 91 accError_ *= (inMax - inMin) / inSpan_;
aberk 0:6e12a3e5af19 92
aberk 0:6e12a3e5af19 93 //Make sure the working variables are within the new limits.
aberk 0:6e12a3e5af19 94 if (prevProcessVariable_ > 1) {
aberk 0:6e12a3e5af19 95 prevProcessVariable_ = 1;
aberk 0:6e12a3e5af19 96 } else if (prevProcessVariable_ < 0) {
aberk 0:6e12a3e5af19 97 prevProcessVariable_ = 0;
aberk 0:6e12a3e5af19 98 }
aberk 0:6e12a3e5af19 99
aberk 0:6e12a3e5af19 100 inMin_ = inMin;
aberk 0:6e12a3e5af19 101 inMax_ = inMax;
aberk 0:6e12a3e5af19 102 inSpan_ = inMax - inMin;
aberk 0:6e12a3e5af19 103
aberk 0:6e12a3e5af19 104 }
aberk 0:6e12a3e5af19 105
kenjiArai 1:ca4077d72c94 106 void PID::setOutputLimits(double outMin, double outMax) {
aberk 0:6e12a3e5af19 107
aberk 0:6e12a3e5af19 108 //Make sure we haven't been given impossible values.
aberk 0:6e12a3e5af19 109 if (outMin >= outMax) {
aberk 0:6e12a3e5af19 110 return;
aberk 0:6e12a3e5af19 111 }
aberk 0:6e12a3e5af19 112
aberk 0:6e12a3e5af19 113 //Rescale the working variables to reflect the changes.
aberk 0:6e12a3e5af19 114 prevControllerOutput_ *= (outMax - outMin) / outSpan_;
aberk 0:6e12a3e5af19 115
aberk 0:6e12a3e5af19 116 //Make sure the working variables are within the new limits.
aberk 0:6e12a3e5af19 117 if (prevControllerOutput_ > 1) {
aberk 0:6e12a3e5af19 118 prevControllerOutput_ = 1;
aberk 0:6e12a3e5af19 119 } else if (prevControllerOutput_ < 0) {
aberk 0:6e12a3e5af19 120 prevControllerOutput_ = 0;
aberk 0:6e12a3e5af19 121 }
aberk 0:6e12a3e5af19 122
aberk 0:6e12a3e5af19 123 outMin_ = outMin;
aberk 0:6e12a3e5af19 124 outMax_ = outMax;
aberk 0:6e12a3e5af19 125 outSpan_ = outMax - outMin;
aberk 0:6e12a3e5af19 126
aberk 0:6e12a3e5af19 127 }
aberk 0:6e12a3e5af19 128
kenjiArai 1:ca4077d72c94 129 void PID::setTunings(double Kc, double tauI, double tauD) {
aberk 0:6e12a3e5af19 130
aberk 0:6e12a3e5af19 131 //Verify that the tunings make sense.
aberk 0:6e12a3e5af19 132 if (Kc == 0.0 || tauI < 0.0 || tauD < 0.0) {
aberk 0:6e12a3e5af19 133 return;
aberk 0:6e12a3e5af19 134 }
aberk 0:6e12a3e5af19 135
aberk 0:6e12a3e5af19 136 //Store raw values to hand back to user on request.
aberk 0:6e12a3e5af19 137 pParam_ = Kc;
aberk 0:6e12a3e5af19 138 iParam_ = tauI;
aberk 0:6e12a3e5af19 139 dParam_ = tauD;
aberk 0:6e12a3e5af19 140
kenjiArai 1:ca4077d72c94 141 double tempTauR;
aberk 0:6e12a3e5af19 142
aberk 0:6e12a3e5af19 143 if (tauI == 0.0) {
aberk 0:6e12a3e5af19 144 tempTauR = 0.0;
aberk 0:6e12a3e5af19 145 } else {
aberk 0:6e12a3e5af19 146 tempTauR = (1.0 / tauI) * tSample_;
aberk 0:6e12a3e5af19 147 }
aberk 0:6e12a3e5af19 148
aberk 0:6e12a3e5af19 149 //For "bumpless transfer" we need to rescale the accumulated error.
aberk 0:6e12a3e5af19 150 if (inAuto) {
aberk 0:6e12a3e5af19 151 if (tempTauR == 0.0) {
aberk 0:6e12a3e5af19 152 accError_ = 0.0;
aberk 0:6e12a3e5af19 153 } else {
aberk 0:6e12a3e5af19 154 accError_ *= (Kc_ * tauR_) / (Kc * tempTauR);
aberk 0:6e12a3e5af19 155 }
aberk 0:6e12a3e5af19 156 }
aberk 0:6e12a3e5af19 157
aberk 0:6e12a3e5af19 158 Kc_ = Kc;
aberk 0:6e12a3e5af19 159 tauR_ = tempTauR;
aberk 0:6e12a3e5af19 160 tauD_ = tauD / tSample_;
aberk 0:6e12a3e5af19 161
aberk 0:6e12a3e5af19 162 }
aberk 0:6e12a3e5af19 163
aberk 0:6e12a3e5af19 164 void PID::reset(void) {
aberk 0:6e12a3e5af19 165
kenjiArai 1:ca4077d72c94 166 double scaledBias = 0.0;
aberk 0:6e12a3e5af19 167
aberk 0:6e12a3e5af19 168 if (usingFeedForward) {
aberk 0:6e12a3e5af19 169 scaledBias = (bias_ - outMin_) / outSpan_;
aberk 0:6e12a3e5af19 170 } else {
aberk 0:6e12a3e5af19 171 scaledBias = (realOutput_ - outMin_) / outSpan_;
aberk 0:6e12a3e5af19 172 }
aberk 0:6e12a3e5af19 173
aberk 0:6e12a3e5af19 174 prevControllerOutput_ = scaledBias;
aberk 0:6e12a3e5af19 175 prevProcessVariable_ = (processVariable_ - inMin_) / inSpan_;
aberk 0:6e12a3e5af19 176
aberk 0:6e12a3e5af19 177 //Clear any error in the integral.
aberk 0:6e12a3e5af19 178 accError_ = 0;
aberk 0:6e12a3e5af19 179
aberk 0:6e12a3e5af19 180 }
aberk 0:6e12a3e5af19 181
aberk 0:6e12a3e5af19 182 void PID::setMode(int mode) {
aberk 0:6e12a3e5af19 183
aberk 0:6e12a3e5af19 184 //We were in manual, and we just got set to auto.
aberk 0:6e12a3e5af19 185 //Reset the controller internals.
aberk 0:6e12a3e5af19 186 if (mode != 0 && !inAuto) {
aberk 0:6e12a3e5af19 187 reset();
aberk 0:6e12a3e5af19 188 }
aberk 0:6e12a3e5af19 189
aberk 0:6e12a3e5af19 190 inAuto = (mode != 0);
aberk 0:6e12a3e5af19 191
aberk 0:6e12a3e5af19 192 }
aberk 0:6e12a3e5af19 193
kenjiArai 1:ca4077d72c94 194 void PID::setInterval(double interval) {
aberk 0:6e12a3e5af19 195
aberk 0:6e12a3e5af19 196 if (interval > 0) {
aberk 0:6e12a3e5af19 197 //Convert the time-based tunings to reflect this change.
aberk 0:6e12a3e5af19 198 tauR_ *= (interval / tSample_);
aberk 0:6e12a3e5af19 199 accError_ *= (tSample_ / interval);
aberk 0:6e12a3e5af19 200 tauD_ *= (interval / tSample_);
aberk 0:6e12a3e5af19 201 tSample_ = interval;
aberk 0:6e12a3e5af19 202 }
aberk 0:6e12a3e5af19 203
aberk 0:6e12a3e5af19 204 }
aberk 0:6e12a3e5af19 205
kenjiArai 1:ca4077d72c94 206 void PID::setSetPoint(double sp) {
aberk 0:6e12a3e5af19 207
aberk 0:6e12a3e5af19 208 setPoint_ = sp;
aberk 0:6e12a3e5af19 209
aberk 0:6e12a3e5af19 210 }
aberk 0:6e12a3e5af19 211
kenjiArai 1:ca4077d72c94 212 void PID::setProcessValue(double pv) {
aberk 0:6e12a3e5af19 213
aberk 0:6e12a3e5af19 214 processVariable_ = pv;
aberk 0:6e12a3e5af19 215
aberk 0:6e12a3e5af19 216 }
aberk 0:6e12a3e5af19 217
kenjiArai 1:ca4077d72c94 218 void PID::setBias(double bias){
aberk 0:6e12a3e5af19 219
aberk 0:6e12a3e5af19 220 bias_ = bias;
aberk 0:6e12a3e5af19 221 usingFeedForward = 1;
aberk 0:6e12a3e5af19 222
aberk 0:6e12a3e5af19 223 }
aberk 0:6e12a3e5af19 224
kenjiArai 1:ca4077d72c94 225 double PID::compute() {
aberk 0:6e12a3e5af19 226
aberk 0:6e12a3e5af19 227 //Pull in the input and setpoint, and scale them into percent span.
kenjiArai 1:ca4077d72c94 228 double scaledPV = (processVariable_ - inMin_) / inSpan_;
aberk 0:6e12a3e5af19 229
aberk 0:6e12a3e5af19 230 if (scaledPV > 1.0) {
aberk 0:6e12a3e5af19 231 scaledPV = 1.0;
aberk 0:6e12a3e5af19 232 } else if (scaledPV < 0.0) {
aberk 0:6e12a3e5af19 233 scaledPV = 0.0;
aberk 0:6e12a3e5af19 234 }
aberk 0:6e12a3e5af19 235
kenjiArai 1:ca4077d72c94 236 double scaledSP = (setPoint_ - inMin_) / inSpan_;
aberk 0:6e12a3e5af19 237 if (scaledSP > 1.0) {
aberk 0:6e12a3e5af19 238 scaledSP = 1;
aberk 0:6e12a3e5af19 239 } else if (scaledSP < 0.0) {
aberk 0:6e12a3e5af19 240 scaledSP = 0;
aberk 0:6e12a3e5af19 241 }
aberk 0:6e12a3e5af19 242
kenjiArai 1:ca4077d72c94 243 double error = scaledSP - scaledPV;
aberk 0:6e12a3e5af19 244
aberk 0:6e12a3e5af19 245 //Check and see if the output is pegged at a limit and only
aberk 0:6e12a3e5af19 246 //integrate if it is not. This is to prevent reset-windup.
aberk 0:6e12a3e5af19 247 if (!(prevControllerOutput_ >= 1 && error > 0) && !(prevControllerOutput_ <= 0 && error < 0)) {
aberk 0:6e12a3e5af19 248 accError_ += error;
aberk 0:6e12a3e5af19 249 }
aberk 0:6e12a3e5af19 250
aberk 0:6e12a3e5af19 251 //Compute the current slope of the input signal.
kenjiArai 1:ca4077d72c94 252 double dMeas = (scaledPV - prevProcessVariable_) / tSample_;
aberk 0:6e12a3e5af19 253
kenjiArai 1:ca4077d72c94 254 double scaledBias = 0.0;
aberk 0:6e12a3e5af19 255
aberk 0:6e12a3e5af19 256 if (usingFeedForward) {
aberk 0:6e12a3e5af19 257 scaledBias = (bias_ - outMin_) / outSpan_;
aberk 0:6e12a3e5af19 258 }
aberk 0:6e12a3e5af19 259
aberk 0:6e12a3e5af19 260 //Perform the PID calculation.
aberk 0:6e12a3e5af19 261 controllerOutput_ = scaledBias + Kc_ * (error + (tauR_ * accError_) - (tauD_ * dMeas));
aberk 0:6e12a3e5af19 262
aberk 0:6e12a3e5af19 263 //Make sure the computed output is within output constraints.
aberk 0:6e12a3e5af19 264 if (controllerOutput_ < 0.0) {
aberk 0:6e12a3e5af19 265 controllerOutput_ = 0.0;
aberk 0:6e12a3e5af19 266 } else if (controllerOutput_ > 1.0) {
aberk 0:6e12a3e5af19 267 controllerOutput_ = 1.0;
aberk 0:6e12a3e5af19 268 }
aberk 0:6e12a3e5af19 269
aberk 0:6e12a3e5af19 270 //Remember this output for the windup check next time.
aberk 0:6e12a3e5af19 271 prevControllerOutput_ = controllerOutput_;
aberk 0:6e12a3e5af19 272 //Remember the input for the derivative calculation next time.
aberk 0:6e12a3e5af19 273 prevProcessVariable_ = scaledPV;
aberk 0:6e12a3e5af19 274
aberk 0:6e12a3e5af19 275 //Scale the output from percent span back out to a real world number.
aberk 0:6e12a3e5af19 276 return ((controllerOutput_ * outSpan_) + outMin_);
aberk 0:6e12a3e5af19 277
aberk 0:6e12a3e5af19 278 }
aberk 0:6e12a3e5af19 279
kenjiArai 1:ca4077d72c94 280 double PID::getInMin() {
aberk 0:6e12a3e5af19 281
aberk 0:6e12a3e5af19 282 return inMin_;
aberk 0:6e12a3e5af19 283
aberk 0:6e12a3e5af19 284 }
aberk 0:6e12a3e5af19 285
kenjiArai 1:ca4077d72c94 286 double PID::getInMax() {
aberk 0:6e12a3e5af19 287
aberk 0:6e12a3e5af19 288 return inMax_;
aberk 0:6e12a3e5af19 289
aberk 0:6e12a3e5af19 290 }
aberk 0:6e12a3e5af19 291
kenjiArai 1:ca4077d72c94 292 double PID::getOutMin() {
aberk 0:6e12a3e5af19 293
aberk 0:6e12a3e5af19 294 return outMin_;
aberk 0:6e12a3e5af19 295
aberk 0:6e12a3e5af19 296 }
aberk 0:6e12a3e5af19 297
kenjiArai 1:ca4077d72c94 298 double PID::getOutMax() {
aberk 0:6e12a3e5af19 299
aberk 0:6e12a3e5af19 300 return outMax_;
aberk 0:6e12a3e5af19 301
aberk 0:6e12a3e5af19 302 }
aberk 0:6e12a3e5af19 303
kenjiArai 1:ca4077d72c94 304 double PID::getInterval() {
aberk 0:6e12a3e5af19 305
aberk 0:6e12a3e5af19 306 return tSample_;
aberk 0:6e12a3e5af19 307
aberk 0:6e12a3e5af19 308 }
aberk 0:6e12a3e5af19 309
kenjiArai 1:ca4077d72c94 310 double PID::getPParam() {
aberk 0:6e12a3e5af19 311
aberk 0:6e12a3e5af19 312 return pParam_;
aberk 0:6e12a3e5af19 313
aberk 0:6e12a3e5af19 314 }
aberk 0:6e12a3e5af19 315
kenjiArai 1:ca4077d72c94 316 double PID::getIParam() {
aberk 0:6e12a3e5af19 317
aberk 0:6e12a3e5af19 318 return iParam_;
aberk 0:6e12a3e5af19 319
aberk 0:6e12a3e5af19 320 }
aberk 0:6e12a3e5af19 321
kenjiArai 1:ca4077d72c94 322 double PID::getDParam() {
aberk 0:6e12a3e5af19 323
aberk 0:6e12a3e5af19 324 return dParam_;
aberk 0:6e12a3e5af19 325
aberk 0:6e12a3e5af19 326 }