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/****************************************************************************
*
* Copyright (c) 2013 Estimation and Control Library (ECL). All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 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
* distribution.
* 3. Neither the name ECL nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file ecl_roll_controller.cpp
* Implementation of a simple orthogonal roll PID controller.
*
* Authors and acknowledgements in header.
*/
#include <ecl/ecl.h>
#include "ecl_roll_controller.h"
#include <stdint.h>
#include <float.h>
#include <geo/geo.h>
#include <ecl/ecl.h>
#include <mathlib/mathlib.h>
#include <systemlib/err.h>
ECL_RollController::ECL_RollController() :
ECL_Controller("roll")
{
}
ECL_RollController::~ECL_RollController()
{
}
float ECL_RollController::control_attitude(const struct ECL_ControlData &ctl_data)
{
/* Do not calculate control signal with bad inputs */
if (!(isfinite(ctl_data.roll_setpoint) && isfinite(ctl_data.roll))) {
perf_count(_nonfinite_input_perf);
return _rate_setpoint;
}
/* Calculate error */
float roll_error = ctl_data.roll_setpoint - ctl_data.roll;
/* Apply P controller */
_rate_setpoint = roll_error / _tc;
/* limit the rate */ //XXX: move to body angluar rates
if (_max_rate > 0.01f) {
_rate_setpoint = (_rate_setpoint > _max_rate) ? _max_rate : _rate_setpoint;
_rate_setpoint = (_rate_setpoint < -_max_rate) ? -_max_rate : _rate_setpoint;
}
return _rate_setpoint;
}
float ECL_RollController::control_bodyrate(const struct ECL_ControlData &ctl_data)
{
/* Do not calculate control signal with bad inputs */
if (!(isfinite(ctl_data.pitch) &&
isfinite(ctl_data.roll_rate) &&
isfinite(ctl_data.yaw_rate) &&
isfinite(ctl_data.yaw_rate_setpoint) &&
isfinite(ctl_data.airspeed_min) &&
isfinite(ctl_data.airspeed_max) &&
isfinite(ctl_data.scaler))) {
perf_count(_nonfinite_input_perf);
return math::constrain(_last_output, -1.0f, 1.0f);
}
/* get the usual dt estimate */
uint64_t dt_micros = ecl_elapsed_time(&_last_run);
_last_run = ecl_absolute_time();
float dt = (float)dt_micros * 1e-6f;
/* lock integral for long intervals */
bool lock_integrator = ctl_data.lock_integrator;
if (dt_micros > 500000) {
lock_integrator = true;
}
/* Transform setpoint to body angular rates (jacobian) */
_bodyrate_setpoint = _rate_setpoint - sinf(ctl_data.pitch) * ctl_data.yaw_rate_setpoint;
/* Transform estimation to body angular rates (jacobian) */
float roll_bodyrate = ctl_data.roll_rate - sinf(ctl_data.pitch) * ctl_data.yaw_rate;
/* Calculate body angular rate error */
_rate_error = _bodyrate_setpoint - roll_bodyrate; //body angular rate error
if (!lock_integrator && _k_i > 0.0f) {
float id = _rate_error * dt * ctl_data.scaler;
/*
* anti-windup: do not allow integrator to increase if actuator is at limit
*/
if (_last_output < -1.0f) {
/* only allow motion to center: increase value */
id = math::max(id, 0.0f);
} else if (_last_output > 1.0f) {
/* only allow motion to center: decrease value */
id = math::min(id, 0.0f);
}
_integrator += id;
}
/* integrator limit */
//xxx: until start detection is available: integral part in control signal is limited here
float integrator_constrained = math::constrain(_integrator * _k_i, -_integrator_max, _integrator_max);
//warnx("roll: _integrator: %.4f, _integrator_max: %.4f", (double)_integrator, (double)_integrator_max);
/* Apply PI rate controller and store non-limited output */
_last_output = _bodyrate_setpoint * _k_ff * ctl_data.scaler +
_rate_error * _k_p * ctl_data.scaler * ctl_data.scaler
+ integrator_constrained; //scaler is proportional to 1/airspeed
return math::constrain(_last_output, -1.0f, 1.0f);
}
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