ManualVelocitySmoothingZ.cpp

Go to the documentation of this file.

/****************************************************************************
 *
 *   Copyright (c) 2019 PX4 Development Team. 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 PX4 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.
 *
 ****************************************************************************/

#include "ManualVelocitySmoothingZ.hpp"

#include <mathlib/mathlib.h>
#include <float.h>

void ManualVelocitySmoothingZ::reset(float accel, float vel, float pos)
{
    _trajectory.reset(accel, vel, pos);

    resetPositionLock();
}

void ManualVelocitySmoothingZ::resetPositionLock()
{
    _position_lock_active = false;
    _position_setpoint_locked = NAN;
}

void ManualVelocitySmoothingZ::update(float dt, float velocity_target)
{
    // Update state
    updateTrajectories(dt);

    // Set max accel/vel/jerk
    // Has to be done before _updateTrajDurations()
    updateTrajConstraints(velocity_target);

    // Lock or unlock position
    // Has to be done before _updateTrajDurations()
    checkPositionLock(velocity_target);

    // Update durations
    _trajectory.updateDurations(velocity_target);
}

void ManualVelocitySmoothingZ::updateTrajectories(float dt)
{
    _trajectory.updateTraj(dt);

    _state.j = _trajectory.getCurrentJerk();
    _state.a = _trajectory.getCurrentAcceleration();
    _state.v = _trajectory.getCurrentVelocity();
    _state.x = _trajectory.getCurrentPosition();
}

void ManualVelocitySmoothingZ::updateTrajConstraints(float velocity_target)
{
    if (velocity_target < 0.f) { // up
        _trajectory.setMaxAccel(_max_accel_up);
        _trajectory.setMaxVel(_max_vel_up);

    } else { // down
        _trajectory.setMaxAccel(_max_accel_down);
        _trajectory.setMaxVel(_max_vel_down);
    }
}

void ManualVelocitySmoothingZ::checkPositionLock(float velocity_target)
{
    /**
     * During a position lock -> position unlock transition, we have to make sure that the velocity setpoint
     * is continuous. We know that the output of the position loop (part of the velocity setpoint)
     * will suddenly become null
     * and only the feedforward (generated by this flight task) will remain.
     * This is why the previous input of the velocity controller
     * is used to set current velocity of the trajectory.
     */
    if (fabsf(_state.v) < 0.1f &&
        fabsf(_state.a) < .2f &&
        fabsf(velocity_target) <= FLT_EPSILON) {
        // Lock position
        _position_lock_active = true;
        _position_setpoint_locked = _state.x;

    } else {
        // Unlock position
        if (_position_lock_active) {
            // Start the trajectory at the current velocity setpoint
            _trajectory.setCurrentVelocity(_velocity_setpoint_feedback);
            _state.v = _velocity_setpoint_feedback;
            resetPositionLock();
        }

        _trajectory.setCurrentPosition(_position_estimate);
    }
}