diff options
Diffstat (limited to 'src/lib/ecl/attitude_fw/ecl_roll_controller.cpp')
| -rw-r--r-- | src/lib/ecl/attitude_fw/ecl_roll_controller.cpp | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp b/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp new file mode 100644 index 000000000..0b1ffa7a4 --- /dev/null +++ b/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp @@ -0,0 +1,129 @@ +/**************************************************************************** + * + * 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.h" +#include "ecl_roll_controller.h" +#include <stdint.h> +#include <float.h> +#include <geo/geo.h> +#include <ecl/ecl.h> +#include <mathlib/mathlib.h> + +ECL_RollController::ECL_RollController() : + _last_run(0), + _tc(0.1f), + _last_output(0.0f), + _integrator(0.0f), + _rate_error(0.0f), + _rate_setpoint(0.0f), + _max_deflection_rad(math::radians(45.0f)) +{ + +} + +float ECL_RollController::control(float roll_setpoint, float roll, float roll_rate, + float scaler, bool lock_integrator, float airspeed_min, float airspeed_max, float airspeed) +{ + /* 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 */ + if (dt_micros > 500000) + lock_integrator = true; + + float k_ff = math::max((_k_p - _k_i * _tc) * _tc - _k_d, 0.0f); + float k_i_rate = _k_i * _tc; + + /* input conditioning */ + if (!isfinite(airspeed)) { + /* airspeed is NaN, +- INF or not available, pick center of band */ + airspeed = 0.5f * (airspeed_min + airspeed_max); + } else if (airspeed < airspeed_min) { + airspeed = airspeed_min; + } + + float roll_error = roll_setpoint - roll; + _rate_setpoint = roll_error / _tc; + + /* limit the rate */ + 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; + } + + _rate_error = _rate_setpoint - roll_rate; + + + float ilimit_scaled = _integrator_max * scaler; + + if (!lock_integrator && k_i_rate > 0.0f && airspeed > 0.5f * airspeed_min) { + + float id = _rate_error * k_i_rate * dt * scaler; + + /* + * anti-windup: do not allow integrator to increase into the + * wrong direction if actuator is at limit + */ + if (_last_output < -_max_deflection_rad) { + /* only allow motion to center: increase value */ + id = math::max(id, 0.0f); + } else if (_last_output > _max_deflection_rad) { + /* only allow motion to center: decrease value */ + id = math::min(id, 0.0f); + } + + _integrator += id; + } + + /* integrator limit */ + _integrator = math::constrain(_integrator, -ilimit_scaled, ilimit_scaled); + /* store non-limited output */ + _last_output = ((_rate_error * _k_d * scaler) + _integrator + (_rate_setpoint * k_ff)) * scaler; + + return math::constrain(_last_output, -_max_deflection_rad, _max_deflection_rad); +} + +void ECL_RollController::reset_integrator() +{ + _integrator = 0.0f; +} + |