mirror of https://github.com/ArduPilot/ardupilot
125 lines
3.5 KiB
C++
125 lines
3.5 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, with EEPROM-backed storage of constants.
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#include <math.h>
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#include <avr/eeprom.h>
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#include "PID.h"
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// make the gain array members a little easier to identify
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#define _kp _gain_array[0]
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#define _ki _gain_array[1]
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#define _kd _gain_array[2]
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#define _imax _gain_array[3]
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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 (_kd && (dt > 0)) {
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float derivative = (error - _last_error) / 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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derivative = _last_derivative +
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((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 (_ki && (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::imax(float v)
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{
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_imax = fabs(v);
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}
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void
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PID::load_gains()
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{
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switch(_storage)
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{
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case STORE_OFF:
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// load is a NOP if the gain array is managed externally
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break;
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case STORE_EEPROM_UINT16:
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// _kp = (float)(eeprom_read_word((uint16_t *) _address)) / 1000.0;
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// _ki = (float)(eeprom_read_word((uint16_t *) (_address + 2))) / 1000.0;
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//_kd = (float)(eeprom_read_word((uint16_t *) (_address + 4))) / 1000.0;
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//_imax = eeprom_read_word((uint16_t *) (_address + 6)) * 100;
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_kp = (float)_ee.read_int(_address) / 1000.0;
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_ki = (float)_ee.read_int(_address + 2) / 1000.0;
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_kd = (float)_ee.read_int(_address + 4) / 1000.0;
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_imax = (float)_ee.read_int(_address + 6) * 100;
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break;
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case STORE_EEPROM_FLOAT:
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//eeprom_read_block((void*)&_kp,(const void*)(_address),sizeof(_kp));
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//eeprom_read_block((void*)&_ki,(const void*)(_address+4),sizeof(_ki));
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//eeprom_read_block((void*)&_kd,(const void*)(_address+8),sizeof(_kd));
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//eeprom_read_block((void*)&_imax,(const void*)(_address+12),sizeof(_imax));
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break;
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}
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}
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void
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PID::save_gains()
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{
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switch(_storage)
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{
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case STORE_OFF:
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// save is a NOP if the gain array is managed externally
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break;
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case STORE_EEPROM_UINT16:
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/*
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eeprom_write_word((uint16_t *) _address, (int)(_kp * 1000));
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eeprom_write_word((uint16_t *) (_address + 2), (int)(_ki * 1000));
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eeprom_write_word((uint16_t *) (_address + 4), (int)(_kd * 1000));
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eeprom_write_word((uint16_t *) (_address + 6), (int)_imax/100);
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*/
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_ee.write_int(_address, (int)(_kp * 1000));
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_ee.write_int(_address + 2, (int)(_ki * 1000));
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_ee.write_int(_address + 4, (int)(_kd * 1000));
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_ee.write_int(_address + 6, (int)(_imax /100));
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break;
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case STORE_EEPROM_FLOAT:
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//eeprom_write_block((const void *)&_kp,(void *)(_address),sizeof(_kp));
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//eeprom_write_block((const void *)&_ki,(void *)(_address+4),sizeof(_ki));
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//eeprom_write_block((const void *)&_kd,(void *)(_address+8),sizeof(_kd));
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//eeprom_write_block((const void *)&_imax,(void *)(_address+12),sizeof(_imax));
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break;
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}
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}
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