PX4-Autopilot/src/modules/spacecraft/SpacecraftAttitudeControl/AttitudeControl/AttitudeControl.hpp

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/**
 * @file AttitudeControl.hpp
 *
 * A quaternion based attitude controller.
 *
 * @author Matthias Grob	<maetugr@gmail.com>
 *
 * Publication documenting the implemented Quaternion Attitude Control:
 * Nonlinear Quadrocopter Attitude Control (2013)
 * by Dario Brescianini, Markus Hehn and Raffaello D'Andrea
 * Institute for Dynamic Systems and Control (IDSC), ETH Zurich
 *
 * https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/154099/eth-7387-01.pdf
 */

#pragma once

#include <matrix/matrix/math.hpp>
#include <mathlib/math/Limits.hpp>

class ScAttitudeControl
{
public:
	ScAttitudeControl() = default;
	~ScAttitudeControl() = default;

	/**
	 * Set proportional attitude control gain
	 * @param proportional_gain 3D vector containing gains for roll, pitch, yaw
	 */
	void setProportionalGain(const matrix::Vector3f &proportional_gain);

	/**
	 * Set hard limit for output rate setpoints
	 * @param rate_limit [rad/s] 3D vector containing limits for roll, pitch, yaw
	 */
	void setRateLimit(const matrix::Vector3f &rate_limit) { _rate_limit = rate_limit; }

	/**
	 * Set a new attitude setpoint replacing the one tracked before
	 * @param qd desired vehicle attitude setpoint
	 */
	void setAttitudeSetpoint(const matrix::Quatf &qd)
	{
		_attitude_setpoint_q = qd;
		_attitude_setpoint_q.normalize();
	}

	/**
	 * Adjust last known attitude setpoint by a delta rotation
	 * Optional use to avoid glitches when attitude estimate reference e.g. heading changes.
	 * @param q_delta delta rotation to apply
	 */
	void adaptAttitudeSetpoint(const matrix::Quatf &q_delta)
	{
		_attitude_setpoint_q = q_delta * _attitude_setpoint_q;
		_attitude_setpoint_q.normalize();
	}

	/**
	 * Run one control loop cycle calculation
	 * @param q estimation of the current vehicle attitude unit quaternion
	 * @return [rad/s] body frame 3D angular rate setpoint vector to be executed by the rate controller
	 */
	matrix::Vector3f update(const matrix::Quatf &q) const;

private:
	matrix::Vector3f _proportional_gain;
	matrix::Vector3f _rate_limit;

	matrix::Quatf _attitude_setpoint_q; ///< latest known attitude setpoint e.g. from position control
};