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f528c63030
This adds a second put method to the integrator class. This allows to integrate with known intervals between samples, rather than based on timestamps. This makes integrating the samples coming out of the MPU9250 FIFO buffer easier.
156 lines
4.4 KiB
C++
156 lines
4.4 KiB
C++
/****************************************************************************
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*
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* Copyright (c) 2015-2016 PX4 Development Team. All rights reserved.
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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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* 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 integrator.cpp
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*
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* A resettable integrator
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*
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* @author Lorenz Meier <lorenz@px4.io>
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* @author Julian Oes <julian@oes.ch>
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*/
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#include "integrator.h"
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Integrator::Integrator(uint64_t auto_reset_interval, bool coning_compensation) :
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_auto_reset_interval(auto_reset_interval),
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_last_integration_time(0),
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_last_reset_time(0),
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_integral(0.0f, 0.0f, 0.0f),
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_last_val(0.0f, 0.0f, 0.0f),
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_last_delta(0.0f, 0.0f, 0.0f),
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_coning_comp_on(coning_compensation)
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{
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}
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Integrator::~Integrator()
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{
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}
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bool
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Integrator::put(uint64_t timestamp, math::Vector<3> &val, math::Vector<3> &integral, uint64_t &integral_dt)
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{
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if (_last_integration_time == 0) {
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/* this is the first item in the integrator */
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_last_integration_time = timestamp;
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_last_reset_time = timestamp;
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_last_val = val;
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return false;
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}
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double dt = 0.0;
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// Integrate:
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// Leave dt at 0 if the integration time does not make sense.
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// Without this check the integral is likely to explode.
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if (timestamp >= _last_integration_time) {
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dt = (double)(timestamp - _last_integration_time) / 1000000.0;
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}
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math::Vector<3> delta = (val + _last_val) * dt * 0.5f;
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// Apply coning compensation if required
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if (_coning_comp_on) {
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// Coning compensation derived by Paul Riseborough and Jonathan Challinger,
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// following:
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// Tian et al (2010) Three-loop Integration of GPS and Strapdown INS with Coning and Sculling Compensation
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// Available: http://www.sage.unsw.edu.au/snap/publications/tian_etal2010b.pdf
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delta += ((_integral + _last_delta * (1.0f / 6.0f)) % delta) * 0.5f;
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}
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_integral += delta;
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_last_integration_time = timestamp;
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_last_val = val;
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_last_delta = delta;
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// Only do auto reset if auto reset interval is not 0.
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if (_auto_reset_interval > 0 && (timestamp - _last_reset_time) > _auto_reset_interval) {
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integral = _integral;
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_reset(integral_dt);
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return true;
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} else {
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return false;
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}
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}
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bool
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Integrator::put_with_interval(unsigned interval_us, math::Vector<3> &val, math::Vector<3> &integral,
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uint64_t &integral_dt)
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{
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if (_last_integration_time == 0) {
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/* this is the first item in the integrator */
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uint64_t now = hrt_absolute_time();
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_last_integration_time = now;
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_last_reset_time = now;
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_last_val = val;
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return false;
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}
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// Create the timestamp artifically.
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uint64_t timestamp = _last_integration_time + interval_us;
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return put(timestamp, val, integral, integral_dt);
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}
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math::Vector<3>
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Integrator::get(bool reset, uint64_t &integral_dt)
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{
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math::Vector<3> val = _integral;
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if (reset) {
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_reset(integral_dt);
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}
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return val;
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}
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void
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Integrator::_reset(uint64_t &integral_dt)
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{
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_integral(0) = 0.0f;
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_integral(1) = 0.0f;
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_integral(2) = 0.0f;
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integral_dt = (_last_integration_time - _last_reset_time);
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_last_reset_time = _last_integration_time;
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}
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