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92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilot Math Utilities
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* @{
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* @addtogroup Sine and cosine methods that use a cached lookup table
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* @{
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*
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* @file pid.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief Methods to work with PID structure
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*
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "openpilot.h"
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#include "pid.h"
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//! Private method
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static float bound(float val, float range);
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float pid_apply(struct pid *pid, const float err, float dT)
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{
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float diff = (err - pid->lastErr);
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pid->lastErr = err;
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// Scale up accumulator by 1000 while computing to avoid losing precision
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pid->iAccumulator += err * (pid->i * dT * 1000.0f);
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pid->iAccumulator = bound(pid->iAccumulator, pid->iLim * 1000.0f);
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return ((err * pid->p) + pid->iAccumulator / 1000.0f + (diff * pid->d / dT));
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}
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/**
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* Reset a bit
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* @param[in] pid The pid to reset
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*/
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void pid_zero(struct pid *pid)
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{
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if (!pid)
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return;
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pid->iAccumulator = 0;
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pid->lastErr = 0;
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}
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/**
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* Configure the settings for a pid structure
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* @param[out] pid The PID structure to configure
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* @param[in] p The proportional term
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* @param[in] i The integral term
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* @param[in] d The derivative term
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*/
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void pid_configure(struct pid *pid, float p, float i, float d, float iLim)
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{
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if (!pid)
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return;
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pid->p = p;
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pid->i = i;
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pid->d = d;
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pid->iLim = iLim;
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}
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/**
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* Bound input value between limits
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*/
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static float bound(float val, float range)
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{
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if(val < -range) {
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val = -range;
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} else if(val > range) {
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val = range;
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}
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return val;
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}
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