mirror of https://github.com/ArduPilot/ardupilot
113 lines
2.2 KiB
C++
113 lines
2.2 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
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/// @file PID.cpp
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/// @brief Generic PID algorithm
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#include <math.h>
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#include "PID.h"
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long
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PID::get_pid(int32_t error, uint16_t dt, float scaler)
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{
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float output = 0;
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float delta_time = (float)dt / 1000.0;
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// Compute proportional component
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output += error * _kp;
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// Compute derivative component if time has elapsed
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if ((fabs(_kd) > 0) && (dt > 0)) {
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float derivative;
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// add in
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_filter[_filter_index] = (error - _last_error) / delta_time;
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_filter_index++;
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if(_filter_index >= PID_FILTER_SIZE)
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_filter_index = 0;
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// sum our filter
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for(uint8_t i = 0; i < PID_FILTER_SIZE; i++){
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derivative += _filter[i];
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}
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// grab result
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derivative /= PID_FILTER_SIZE;
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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 = _last_derivative + (delta_time / (RC + delta_time)) * (derivative - _last_derivative);
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// update state
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_last_error = error;
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//_last_derivative = derivative;
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// add in derivative component
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output += _kd * derivative;
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}
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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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return output;
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}
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long
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PID::get_pi(int32_t error, uint16_t dt, float scaler)
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{
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float output = 0;
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float delta_time = (float)dt / 1000.0;
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// Compute proportional component
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output += error * _kp;
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// scale the P 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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return output;
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}
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void
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PID::reset_I()
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{
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_integrator = 0;
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_last_error = 0;
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//_last_derivative = 0;
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}
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void
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PID::load_gains()
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{
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_group.load();
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}
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void
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PID::save_gains()
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{
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_group.save();
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}
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