Lorenz Meier
13 years ago
5 changed files with 166 additions and 204 deletions
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/****************************************************************************
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* |
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* Copyright (C) 2012 PX4 Development Team. All rights reserved. |
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* Author: @author Ivan Ovinnikov <oivan@ethz.ch> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name PX4 nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**
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* @file pid.c |
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* Implementation of a fixed wing attitude and position controller. |
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*/ |
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#include "pid.h" |
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#include "fixedwing_control.h" |
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/*******************************************************************************
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* pid() |
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* |
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* Calculates the PID control output given an error |
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* |
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* Input: float error, uint16_t dt, float scaler, float K_p, float K_i, float K_d |
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* |
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* Output: PID control value |
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* |
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******************************************************************************/ |
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static float pid(float error, float error_deriv, uint16_t dt, float scaler, float K_p, float K_i, float K_d, float intmax) |
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{ |
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// PID parameters
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float Kp = K_p; |
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float Ki = K_i; |
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float Kd = K_d; |
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float delta_time = dt; // delta time
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float lerror; // last error value
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float imax = intmax; // max integral value
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float integrator; |
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float derivative; |
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float lderiv; |
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int fCut = 20; // anything above 20 Hz is considered noise - low pass filter for the derivative
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float output = 0; // the output of the PID controller
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output += error * Kp; |
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if ((fabs(Kd) > 0) && (dt > 0)) { |
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if (PID_DERIVMODE_CALC) { |
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derivative = (error - lerror) / delta_time; |
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// discrete low pass filter, cuts out the
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// high frequency noise that can drive the controller crazy
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float RC = 1 / (2 * M_PI * fCut); |
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derivative = lderiv + |
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(delta_time / (RC + delta_time)) * (derivative - lderiv); |
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// update state
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lerror = error; |
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lderiv = derivative; |
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} else { |
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derivative = error_deriv; |
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} |
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// add in derivative component
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output += Kd * derivative; |
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} |
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printf("PID derivative %i\n", (int)(1000 * derivative)); |
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// scale the P and D components
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output *= scaler; |
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// Compute integral component if time has elapsed
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if ((fabs(Ki) > 0) && (dt > 0)) { |
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integrator += (error * Ki) * scaler * delta_time; |
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if (integrator < -imax) { |
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integrator = -imax; |
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} else if (integrator > imax) { |
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integrator = imax; |
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} |
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output += integrator; |
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} |
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printf("PID Integrator %i\n", (int)(1000 * integrator)); |
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return output; |
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} |
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@ -1,46 +0,0 @@
@@ -1,46 +0,0 @@
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/****************************************************************************
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* pid.h |
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* |
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* Copyright (C) 2012 Ivan Ovinnikov. All rights reserved. |
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* Authors: Ivan Ovinnikov <oivan@ethz.ch> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
||||
* |
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* 1. Redistributions of source code must retain the above copyright |
||||
* notice, this list of conditions and the following disclaimer. |
||||
* 2. Redistributions in binary form must reproduce the above copyright |
||||
* notice, this list of conditions and the following disclaimer in |
||||
* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
||||
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
||||
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
||||
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
||||
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
||||
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
||||
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
||||
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
||||
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
||||
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
||||
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/****************************************************************************
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* Included Files |
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****************************************************************************/ |
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#ifndef PID_H_ |
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#define PID_H_ |
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static float pid(float error, float error_deriv, uint16_t dt, float scaler, float K_p, float K_i, float K_d, float intmax); |
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#endif /* PID_H_ */ |
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