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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_yaw_controller.cpp
* Implementation of a simple orthogonal coordinated turn yaw PID controller.
*
* Authors and acknowledgements in header.
*/
#include "ecl_yaw_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_YawController::ECL_YawController() :
ECL_Controller("yaw"),
_coordinated_min_speed(1.0f)
{
}
ECL_YawController::~ECL_YawController()
{
}
float ECL_YawController::control_attitude(const struct ECL_ControlData &ctl_data)
{
/* Do not calculate control signal with bad inputs */
if (!(isfinite(ctl_data.roll) &&
isfinite(ctl_data.pitch) &&
isfinite(ctl_data.speed_body_u) &&
isfinite(ctl_data.speed_body_v) &&
isfinite(ctl_data.speed_body_w) &&
isfinite(ctl_data.roll_rate_setpoint) &&
isfinite(ctl_data.pitch_rate_setpoint))) {
perf_count(_nonfinite_input_perf);
return _rate_setpoint;
}
// static int counter = 0;
/* Calculate desired yaw rate from coordinated turn constraint / (no side forces) */
_rate_setpoint = 0.0f;
if (sqrtf(ctl_data.speed_body_u * ctl_data.speed_body_u + ctl_data.speed_body_v * ctl_data.speed_body_v +
ctl_data.speed_body_w * ctl_data.speed_body_w) > _coordinated_min_speed) {
float denumerator = (ctl_data.speed_body_u * cosf(ctl_data.roll) * cosf(ctl_data.pitch) +
ctl_data.speed_body_w * sinf(ctl_data.pitch));
if(fabsf(denumerator) > FLT_EPSILON) {
_rate_setpoint = (ctl_data.speed_body_w * ctl_data.roll_rate_setpoint +
9.81f * sinf(ctl_data.roll) * cosf(ctl_data.pitch) +
ctl_data.speed_body_u * ctl_data.pitch_rate_setpoint * sinf(ctl_data.roll)) /
denumerator;
// warnx("yaw: speed_body_u %.f speed_body_w %1.f roll %.1f pitch %.1f denumerator %.1f _rate_setpoint %.1f", speed_body_u, speed_body_w, denumerator, _rate_setpoint);
}
// if(counter % 20 == 0) {
// warnx("denumerator: %.4f, speed_body_u: %.4f, speed_body_w: %.4f, cosf(roll): %.4f, cosf(pitch): %.4f, sinf(pitch): %.4f", (double)denumerator, (double)speed_body_u, (double)speed_body_w, (double)cosf(roll), (double)cosf(pitch), (double)sinf(pitch));
// }
}
/* 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;
}
// counter++;
if(!isfinite(_rate_setpoint)){
warnx("yaw rate sepoint not finite");
_rate_setpoint = 0.0f;
}
return _rate_setpoint;
}
float ECL_YawController::control_bodyrate(const struct ECL_ControlData &ctl_data)
{
/* Do not calculate control signal with bad inputs */
if (!(isfinite(ctl_data.roll) && isfinite(ctl_data.pitch) && isfinite(ctl_data.pitch_rate) &&
isfinite(ctl_data.yaw_rate) && isfinite(ctl_data.pitch_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;
/* input conditioning */
float airspeed = ctl_data.airspeed;
if (!isfinite(airspeed)) {
/* airspeed is NaN, +- INF or not available, pick center of band */
airspeed = 0.5f * (ctl_data.airspeed_min + ctl_data.airspeed_max);
} else if (airspeed < ctl_data.airspeed_min) {
airspeed = ctl_data.airspeed_min;
}
/* Transform setpoint to body angular rates (jacobian) */
_bodyrate_setpoint = -sinf(ctl_data.roll) * ctl_data.pitch_rate_setpoint +
cosf(ctl_data.roll)*cosf(ctl_data.pitch) * _rate_setpoint;
/* Transform estimation to body angular rates (jacobian) */
float yaw_bodyrate = -sinf(ctl_data.roll) * ctl_data.pitch_rate +
cosf(ctl_data.roll)*cosf(ctl_data.pitch) * ctl_data.yaw_rate;
/* Calculate body angular rate error */
_rate_error = _bodyrate_setpoint - yaw_bodyrate; //body angular rate error
if (!lock_integrator && _k_i > 0.0f && airspeed > 0.5f * ctl_data.airspeed_min) {
float id = _rate_error * dt;
/*
* 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);
/* Apply PI rate controller and store non-limited output */
_last_output = (_bodyrate_setpoint * _k_ff + _rate_error * _k_p + integrator_constrained) * ctl_data.scaler * ctl_data.scaler; //scaler is proportional to 1/airspeed
//warnx("yaw:_last_output: %.4f, _integrator: %.4f, _integrator_max: %.4f, airspeed %.4f, _k_i %.4f, _k_p: %.4f", (double)_last_output, (double)_integrator, (double)_integrator_max, (double)airspeed, (double)_k_i, (double)_k_p);
return math::constrain(_last_output, -1.0f, 1.0f);
}
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