MHVLib
20111011
An efficiency oriented runtime library for AVR microcontrollers
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00001 /* 00002 * Based on Arduino PID Library - Version 1 00003 * by Brett Beauregard <br3ttb@gmail.com> brettbeauregard.com 00004 * 00005 * Original code is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License. 00006 * 00007 * MHV version Copyright (c) 2011, Make, Hack, Void Inc 00008 * All rights reserved. 00009 * 00010 * Redistribution and use in source and binary forms, with or without 00011 * modification, are permitted provided that the following conditions are met: 00012 * * Redistributions of source code must retain the above copyright 00013 * notice, this list of conditions and the following disclaimer. 00014 * * Redistributions in binary form must reproduce the above copyright 00015 * notice, this list of conditions and the following disclaimer in the 00016 * documentation and/or other materials provided with the distribution. 00017 * * Neither the name of the Make, Hack, Void nor the 00018 * names of its contributors may be used to endorse or promote products 00019 * derived from this software without specific prior written permission. 00020 * 00021 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 00022 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 00023 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 00024 * DISCLAIMED. IN NO EVENT SHALL MAKE, HACK, VOID BE LIABLE FOR ANY 00025 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 00026 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00027 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 00028 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 00029 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 00030 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00031 */ 00032 00033 #include <MHV_PID.h> 00034 00046 MHV_PID::MHV_PID(float setpoint, float kP, float kI, float kD, uint16_t period, 00047 bool reverse, uint16_t min, uint16_t max) { 00048 _setpoint = setpoint; 00049 00050 setDirection(reverse); 00051 setTuning(kP, kI, kD, period); 00052 00053 _enabled = false; 00054 } 00055 00056 00057 inline void MHV_PID::clampIntegral() { 00058 if (_integral > outMax) { 00059 _integral = outMax; 00060 } else if (_integral < outMin) { 00061 _integral = outMin; 00062 } 00063 } 00064 00069 float MHV_PID::compute(float input) { 00070 float error = _setpoint - input; 00071 00072 _integral += (_kI * error); 00073 00074 clampIntegral(); 00075 00076 float output = _kP * error + _integral - _kD * (input - _lastInput); 00077 00078 if (output > outMax) 00079 output = outMax; 00080 else if (output < outMin) 00081 output = outMin; 00082 00083 _lastInput = input; 00084 _lastOutput = output; 00085 00086 return output; 00087 } 00088 00089 00097 void MHV_PID::setTuning(float kP, float kI, float kD, uint16_t period) { 00098 float myPeriod = period / 1000; 00099 00100 _kP = kP; 00101 _kI = kI * myPeriod; 00102 _kD = kD / myPeriod; 00103 00104 if (_reverse) { 00105 _kP = 0 - _kP; 00106 _kI = 0 - _kI; 00107 _kD = 0 - _kD; 00108 } 00109 } 00110 00111 00117 void MHV_PID::setOutputLimits(float min, float max) { 00118 outMin = min; 00119 outMax = max; 00120 00121 clampIntegral(); 00122 } 00123 00124 00129 void MHV_PID::enable(bool enable) { 00130 if (enable && !_enabled) { 00131 _integral = _lastOutput; 00132 00133 clampIntegral(); 00134 } 00135 _enabled = enable; 00136 } 00137 00138 00145 void MHV_PID::setDirection(bool reverse) { 00146 if (_enabled && reverse != _reverse) { 00147 _kP = 0 - _kP; 00148 _kI = 0 - _kI; 00149 _kD = 0 - _kD; 00150 } 00151 00152 _reverse = reverse; 00153 } 00154