PX4-Autopilot/src/modules/mc_att_control/mc_att_control_base.cpp

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/**
 * @file mc_att_control_base.cpp
 *
 * MC Attitude Controller : Control and math code
 *
 * @author Tobias Naegeli <naegelit@student.ethz.ch>
 * @author Lorenz Meier <lm@inf.ethz.ch>
 * @author Anton Babushkin <anton.babushkin@me.com>
 * @author Thomas Gubler <thomasgubler@gmail.com>
 * @author Julian Oes <julian@oes.ch>
 * @author Roman Bapst <bapstr@ethz.ch>
 *
 */

#include "mc_att_control_base.h"
#include <geo/geo.h>
#include <math.h>
#include <lib/mathlib/mathlib.h>

#ifdef CONFIG_ARCH_ARM
#else
#include <cmath>
using namespace std;
#endif

MulticopterAttitudeControlBase::MulticopterAttitudeControlBase() :
	_publish_att_sp(false)

{
	memset(&_v_att_sp_mod, 0, sizeof(_v_att_sp_mod));
	memset(&_v_rates_sp_mod, 0, sizeof(_v_rates_sp_mod));
	memset(&_actuators, 0, sizeof(_actuators));

	_params.att_p.zero();
	_params.rate_p.zero();
	_params.rate_i.zero();
	_params.rate_d.zero();
	_params.yaw_ff = 0.0f;
	_params.yaw_rate_max = 0.0f;
	_params.man_roll_max = 0.0f;
	_params.man_pitch_max = 0.0f;
	_params.man_yaw_max = 0.0f;
	_params.acro_rate_max.zero();

	_rates_prev.zero();
	_rates_sp.zero();
	_rates_int.zero();
	_thrust_sp = 0.0f;
	_att_control.zero();

	_I.identity();
}

MulticopterAttitudeControlBase::~MulticopterAttitudeControlBase()
{
}

void MulticopterAttitudeControlBase::control_attitude(float dt)
{
	float yaw_sp_move_rate = 0.0f;
	_publish_att_sp = false;


	if (_v_control_mode->get().flag_control_manual_enabled) {
		/* manual input, set or modify attitude setpoint */

		if (_v_control_mode->get().flag_control_velocity_enabled
		    || _v_control_mode->get().flag_control_climb_rate_enabled) {
			/* in assisted modes poll 'vehicle_attitude_setpoint' topic and modify it */
			memcpy(&_v_att_sp_mod, _v_att_sp->get_void_ptr(), sizeof(_v_att_sp_mod));
		}

		if (!_v_control_mode->get().flag_control_climb_rate_enabled) {
			/* pass throttle directly if not in altitude stabilized mode */
			_v_att_sp_mod.thrust = _manual_control_sp->get().z;
			_publish_att_sp = true;
		}

		if (!_armed->get().armed) {
			/* reset yaw setpoint when disarmed */
			_reset_yaw_sp = true;
		}

		/* move yaw setpoint in all modes */
		if (_v_att_sp_mod.thrust < 0.1f) {
			// TODO
			//if (_status.condition_landed) {
			/* reset yaw setpoint if on ground */
			//	reset_yaw_sp = true;
			//}
		} else {
			/* move yaw setpoint */
			yaw_sp_move_rate = _manual_control_sp->get().r * _params.man_yaw_max;
			_v_att_sp_mod.yaw_body = _wrap_pi(
						     _v_att_sp_mod.yaw_body + yaw_sp_move_rate * dt);
			float yaw_offs_max = _params.man_yaw_max / _params.att_p(2);
			float yaw_offs = _wrap_pi(_v_att_sp_mod.yaw_body - _v_att->get().yaw);

			if (yaw_offs < -yaw_offs_max) {
				_v_att_sp_mod.yaw_body = _wrap_pi(_v_att->get().yaw - yaw_offs_max);

			} else if (yaw_offs > yaw_offs_max) {
				_v_att_sp_mod.yaw_body = _wrap_pi(_v_att->get().yaw + yaw_offs_max);
			}

			_v_att_sp_mod.R_valid = false;
			_publish_att_sp = true;
		}

		/* reset yaw setpint to current position if needed */
		if (_reset_yaw_sp) {
			_reset_yaw_sp = false;
			_v_att_sp_mod.yaw_body = _v_att->get().yaw;
			_v_att_sp_mod.R_valid = false;
			_publish_att_sp = true;
		}

		if (!_v_control_mode->get().flag_control_velocity_enabled) {
			/* update attitude setpoint if not in position control mode */
			_v_att_sp_mod.roll_body = _manual_control_sp->get().y * _params.man_roll_max;
			_v_att_sp_mod.pitch_body = -_manual_control_sp->get().x
					       * _params.man_pitch_max;
			_v_att_sp_mod.R_valid = false;
			_publish_att_sp = true;
		}

	} else {
		/* in non-manual mode use 'vehicle_attitude_setpoint' topic */
		memcpy(&_v_att_sp_mod, _v_att_sp->get_void_ptr(), sizeof(_v_att_sp_mod));

		/* reset yaw setpoint after non-manual control mode */
		_reset_yaw_sp = true;
	}

	_thrust_sp = _v_att_sp_mod.thrust;

	/* construct attitude setpoint rotation matrix */
	math::Matrix<3, 3> R_sp;

	if (_v_att_sp_mod.R_valid) {
		/* rotation matrix in _att_sp is valid, use it */
		R_sp.set(&_v_att_sp_mod.R_body[0]);

	} else {
		/* rotation matrix in _att_sp is not valid, use euler angles instead */
		R_sp.from_euler(_v_att_sp_mod.roll_body, _v_att_sp_mod.pitch_body,
				_v_att_sp_mod.yaw_body);

		/* copy rotation matrix back to setpoint struct */
		memcpy(&_v_att_sp_mod.R_body[0], &R_sp.data[0][0],
		       sizeof(_v_att_sp_mod.R_body));
		_v_att_sp_mod.R_valid = true;
	}

	/* rotation matrix for current state */
	math::Matrix<3, 3> R;
	R.set(_v_att->get().R);

	/* all input data is ready, run controller itself */

	/* try to move thrust vector shortest way, because yaw response is slower than roll/pitch */
	math::Vector < 3 > R_z(R(0, 2), R(1, 2), R(2, 2));
	math::Vector < 3 > R_sp_z(R_sp(0, 2), R_sp(1, 2), R_sp(2, 2));

	/* axis and sin(angle) of desired rotation */
	math::Vector < 3 > e_R = R.transposed() * (R_z % R_sp_z);

	/* calculate angle error */
	float e_R_z_sin = e_R.length();
	float e_R_z_cos = R_z * R_sp_z;

	/* calculate weight for yaw control */
	float yaw_w = R_sp(2, 2) * R_sp(2, 2);

	/* calculate rotation matrix after roll/pitch only rotation */
	math::Matrix<3, 3> R_rp;

	if (e_R_z_sin > 0.0f) {
		/* get axis-angle representation */
		float e_R_z_angle = atan2f(e_R_z_sin, e_R_z_cos);
		math::Vector < 3 > e_R_z_axis = e_R / e_R_z_sin;

		e_R = e_R_z_axis * e_R_z_angle;

		/* cross product matrix for e_R_axis */
		math::Matrix<3, 3> e_R_cp;
		e_R_cp.zero();
		e_R_cp(0, 1) = -e_R_z_axis(2);
		e_R_cp(0, 2) = e_R_z_axis(1);
		e_R_cp(1, 0) = e_R_z_axis(2);
		e_R_cp(1, 2) = -e_R_z_axis(0);
		e_R_cp(2, 0) = -e_R_z_axis(1);
		e_R_cp(2, 1) = e_R_z_axis(0);

		/* rotation matrix for roll/pitch only rotation */
		R_rp = R
		       * (_I + e_R_cp * e_R_z_sin
			  + e_R_cp * e_R_cp * (1.0f - e_R_z_cos));

	} else {
		/* zero roll/pitch rotation */
		R_rp = R;
	}

	/* R_rp and R_sp has the same Z axis, calculate yaw error */
	math::Vector < 3 > R_sp_x(R_sp(0, 0), R_sp(1, 0), R_sp(2, 0));
	math::Vector < 3 > R_rp_x(R_rp(0, 0), R_rp(1, 0), R_rp(2, 0));
	e_R(2) = atan2f((R_rp_x % R_sp_x) * R_sp_z, R_rp_x * R_sp_x) * yaw_w;

	if (e_R_z_cos < 0.0f) {
		/* for large thrust vector rotations use another rotation method:
		 * calculate angle and axis for R -> R_sp rotation directly */
		math::Quaternion q;
		q.from_dcm(R.transposed() * R_sp);
		math::Vector < 3 > e_R_d = q.imag();
		e_R_d.normalize();
		e_R_d *= 2.0f * atan2f(e_R_d.length(), q(0));

		/* use fusion of Z axis based rotation and direct rotation */
		float direct_w = e_R_z_cos * e_R_z_cos * yaw_w;
		e_R = e_R * (1.0f - direct_w) + e_R_d * direct_w;
	}

	/* calculate angular rates setpoint */
	_rates_sp = _params.att_p.emult(e_R);

	/* limit yaw rate */
	_rates_sp(2) = math::constrain(_rates_sp(2), -_params.yaw_rate_max,
				       _params.yaw_rate_max);

	/* feed forward yaw setpoint rate */
	_rates_sp(2) += yaw_sp_move_rate * yaw_w * _params.yaw_ff;
}

void MulticopterAttitudeControlBase::control_attitude_rates(float dt)
{
	/* reset integral if disarmed */
	if (!_armed->get().armed || !_v_status->get().is_rotary_wing) {
		_rates_int.zero();
	}

	/* current body angular rates */
	math::Vector < 3 > rates;
	rates(0) = _v_att->get().rollspeed;
	rates(1) = _v_att->get().pitchspeed;
	rates(2) = _v_att->get().yawspeed;

	/* angular rates error */
	math::Vector < 3 > rates_err = _rates_sp - rates;
	_att_control = _params.rate_p.emult(rates_err)
		       + _params.rate_d.emult(_rates_prev - rates) / dt + _rates_int;
	_rates_prev = rates;

	/* update integral only if not saturated on low limit */
	if (_thrust_sp > MIN_TAKEOFF_THRUST) {
		for (int i = 0; i < 3; i++) {
			if (fabsf(_att_control(i)) < _thrust_sp) {
				float rate_i = _rates_int(i)
					       + _params.rate_i(i) * rates_err(i) * dt;

				if (isfinite(
					    rate_i) && rate_i > -RATES_I_LIMIT && rate_i < RATES_I_LIMIT &&
				    _att_control(i) > -RATES_I_LIMIT && _att_control(i) < RATES_I_LIMIT) {
					_rates_int(i) = rate_i;
				}
			}
		}
	}

}

void MulticopterAttitudeControlBase::set_actuator_controls()
{
	_actuators.control[0] = (isfinite(_att_control(0))) ? _att_control(0) : 0.0f;
	_actuators.control[1] = (isfinite(_att_control(1))) ? _att_control(1) : 0.0f;
	_actuators.control[2] = (isfinite(_att_control(2))) ? _att_control(2) : 0.0f;
	_actuators.control[3] = (isfinite(_thrust_sp)) ? _thrust_sp : 0.0f;
}