PX4-Autopilot/src/lib/FlightTasks/tasks/FlightTaskAutoLine.cpp

504 lines
17 KiB
C++

/****************************************************************************
*
* Copyright (c) 2018 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
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* the documentation and/or other materials provided with the
* distribution.
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* 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
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/**
* @file FlightAutoLine.cpp
*/
#include "FlightTaskAutoLine.hpp"
#include <mathlib/mathlib.h>
using namespace matrix;
#define SIGMA_SINGLE_OP 0.000001f
#define SIGMA_NORM 0.001f
FlightTaskAutoLine::FlightTaskAutoLine(control::SuperBlock *parent, const char *name) :
FlightTaskAuto(parent, name),
_land_speed(parent, "MPC_LAND_SPEED", false),
_vel_max_up(parent, "MPC_Z_VEL_MAX_UP", false),
_vel_max_down(parent, "MPC_Z_VEL_MAX_DN", false),
_acc_max_xy(parent, "MPC_ACC_HOR_MAX", false),
_acc_xy(parent, "MPC_ACC_HOR", false),
_acc_max_up(parent, "MPC_ACC_UP_MAX", false),
_acc_max_down(parent, "MPC_ACC_DOWN_MAX", false),
_cruise_speed_90(parent, "MPC_CRUISE_90", false),
_nav_rad(parent, "NAV_ACC_RAD", false),
_mis_yaw_error(parent, "MIS_YAW_ERR", false)
{}
bool FlightTaskAutoLine::activate()
{
_reset();
return FlightTaskAuto::activate();
}
bool FlightTaskAutoLine::update()
{
if (_type == WaypointType::idle) {
_generateIdleSetpoints();
} else if (_type == WaypointType::land) {
_generateLandSetpoints();
} else if (_type == WaypointType::loiter || _type == WaypointType::position) {
_generateSetpoints();
} else if (_type == WaypointType::takeoff) {
_generateTakeoffSetpoints();
} else if (_type == WaypointType::velocity) {
_generateVelocitySetpoints();
}
/* For now yaw setpoint comes directly form triplets */
_setYawSetpoint(_yaw_wp);
return true;
}
void FlightTaskAutoLine::_reset()
{
/* Set setpoints equal current state. */
_vel_sp_xy = matrix::Vector2f(&_velocity(0));
_pos_sp_xy = matrix::Vector2f(&_position(0));
_vel_sp_z = _velocity(2);
_pos_sp_z = _position(2);
_destination = _target;
_origin = _prev_wp;
_speed_at_target = 0.0f;
}
void FlightTaskAutoLine::_generateIdleSetpoints()
{
/* Send zero thrust setpoint */
_setThrustSetpoint(Vector3f(0.0f, 0.0f, 0.0f));
/* Set member setpoints to current state */
_reset();
}
void FlightTaskAutoLine::_generateLandSetpoints()
{
/* Keep xy-position and go down with landspeed. */
_setPositionSetpoint(Vector3f(_target(0), _target(1), NAN));
_setVelocitySetpoint(Vector3f(NAN, NAN, _land_speed.get()));
/* Set member setpoints to current state */
_reset();
}
void FlightTaskAutoLine::_generateTakeoffSetpoints()
{
/* Takeoff is completely defined by position. */
_setPositionSetpoint(_target);
/* Set member setpoints to current state */
_reset();
}
void FlightTaskAutoLine::_generateSetpoints()
{
_updateInternalWaypoints();
_generateAltitudeSetpoints();
_generateXYsetpoints();
_setPositionSetpoint(Vector3f(_pos_sp_xy(0), _pos_sp_xy(1), _pos_sp_z));
_setVelocitySetpoint(Vector3f(_vel_sp_xy(0), _vel_sp_xy(1), _vel_sp_z));
}
void FlightTaskAutoLine::_updateInternalWaypoints()
{
/* The internal Waypoints might differ from previous_wp and target. The cases where it differs:
* 1. The vehicle already passe the target -> go straight to target
* 2. The vehicle is more than cruise speed in front of previous waypoint -> go straight to previous wp
* 3. The vehicle is more than cruise speed from track -> go straight to closest point on track
*
* If a new target is available, then the speed at the target is computed from the angle previous-target-next
*/
/* Adjust destination and origin based on current vehicle state. */
Vector2f u_prev_to_target = Vector2f(&(_target - _prev_wp)(0)).unit_or_zero();
Vector2f pos_to_target = Vector2f(&(_target - _position)(0));
Vector2f prev_to_pos = Vector2f(&(_position - _prev_wp)(0));
Vector2f closest_pt = Vector2f(&_prev_wp(0)) + u_prev_to_target * (prev_to_pos * u_prev_to_target);
if (u_prev_to_target * pos_to_target < 0.0f) {
/* Target is behind. */
if (_current_state != State::target_behind) {
_destination = _target;
_origin = _position;
_current_state = State::target_behind;
float angle = 2.0f;
_speed_at_target = 0.0f;
/* angle = cos(x) + 1.0
* angle goes from 0 to 2 with 0 = large angle, 2 = small angle: 0 = PI ; 2 = PI*0 */
if (Vector2f(&(_destination - _next_wp)(0)).length() > 0.001f &&
(Vector2f(&(_destination - _origin)(0)).length() > _nav_rad.get())) {
angle = Vector2f(&(_destination - _origin)(0)).unit_or_zero()
* Vector2f(&(_destination - _next_wp)(0)).unit_or_zero()
+ 1.0f;
_speed_at_target = _getVelocityFromAngle(angle);
}
}
} else if (u_prev_to_target * prev_to_pos < 0.0f && prev_to_pos.length() > _mc_cruise_speed) {
/* Current position is more than cruise speed in front of previous setpoint. */
if (_current_state != State::previous_infront) {
_destination = _prev_wp;
_origin = _position;
_current_state = State::previous_infront;
float angle = 2.0f;
_speed_at_target = 0.0f;
/* angle = cos(x) + 1.0
* angle goes from 0 to 2 with 0 = large angle, 2 = small angle: 0 = PI ; 2 = PI*0 */
if (Vector2f(&(_destination - _next_wp)(0)).length() > 0.001f &&
(Vector2f(&(_destination - _origin)(0)).length() > _nav_rad.get())) {
angle = Vector2f(&(_destination - _origin)(0)).unit_or_zero()
* Vector2f(&(_destination - _next_wp)(0)).unit_or_zero()
+ 1.0f;
_speed_at_target = _getVelocityFromAngle(angle);
}
}
} else if (Vector2f(Vector2f(&_position(0)) - closest_pt).length() > _mc_cruise_speed) {
/* Vehicle is more than cruise speed off track. */
if (_current_state != State::offtrack) {
_destination = matrix::Vector3f(closest_pt(0), closest_pt(1), _target(2));
_origin = _position;
_current_state = State::offtrack;
float angle = 2.0f;
_speed_at_target = 0.0f;
/* angle = cos(x) + 1.0
* angle goes from 0 to 2 with 0 = large angle, 2 = small angle: 0 = PI ; 2 = PI*0 */
if (Vector2f(&(_destination - _next_wp)(0)).length() > 0.001f &&
(Vector2f(&(_destination - _origin)(0)).length() > _nav_rad.get())) {
angle = Vector2f(&(_destination - _origin)(0)).unit_or_zero()
* Vector2f(&(_destination - _next_wp)(0)).unit_or_zero()
+ 1.0f;
_speed_at_target = _getVelocityFromAngle(angle);
}
}
} else {
if ((_target - _destination).length() > 0.01f) {
/* A new target is available. Update speed at target.*/
_destination = _target;
_origin = _prev_wp;
_current_state = State::none;
float angle = 2.0f;
_speed_at_target = 0.0f;
/* angle = cos(x) + 1.0
* angle goes from 0 to 2 with 0 = large angle, 2 = small angle: 0 = PI ; 2 = PI*0 */
if (Vector2f(&(_destination - _next_wp)(0)).length() > 0.001f &&
(Vector2f(&(_destination - _origin)(0)).length() > _nav_rad.get())) {
angle =
Vector2f(&(_destination - _origin)(0)).unit_or_zero()
* Vector2f(&(_destination - _next_wp)(0)).unit_or_zero()
+ 1.0f;
_speed_at_target = _getVelocityFromAngle(angle);
}
}
}
}
void FlightTaskAutoLine::_generateXYsetpoints()
{
Vector2f pos_sp_to_dest = Vector2f(&_target(0)) - _pos_sp_xy;
const bool has_reached_altitude = fabsf(_destination(2) - _position(2)) < _nav_rad.get();
if ((_speed_at_target < 0.001f && pos_sp_to_dest.length() < _nav_rad.get()) ||
(!has_reached_altitude && pos_sp_to_dest.length() < _nav_rad.get())) {
/* Vehicle reached target in xy and no passing required. Lock position */
_pos_sp_xy = Vector2f(&_destination(0));
_vel_sp_xy.zero();
} else {
/* Get various path specific vectors. */
Vector2f u_prev_to_dest = Vector2f(&(_destination - _origin)(0)).unit_or_zero();
Vector2f prev_to_pos(&(_position - _origin)(0));
Vector2f closest_pt = Vector2f(&_origin(0)) + u_prev_to_dest * (prev_to_pos * u_prev_to_dest);
Vector2f closest_to_dest = Vector2f(&(_destination - _position)(0));
Vector2f prev_to_dest = Vector2f(&(_destination - _origin)(0));
float speed_sp_track = _mc_cruise_speed;
float speed_sp_prev_track = math::max(_vel_sp_xy * u_prev_to_dest, 0.0f);
/* Distance to target when brake should occur. The assumption is made that
* 1.5 * cruising speed is enough to break. */
float target_threshold = 1.5f * _mc_cruise_speed;
float speed_threshold = _mc_cruise_speed;
const float threshold_max = target_threshold;
if (target_threshold < 0.5f * prev_to_dest.length()) {
/* Target threshold cannot be more than distance from previous to target */
target_threshold = 0.5f * prev_to_dest.length();
}
/* Compute maximum speed at target threshold */
if (threshold_max > _nav_rad.get()) {
float m = (_mc_cruise_speed - _speed_at_target) / (threshold_max - _nav_rad.get());
speed_threshold = m * (target_threshold - _nav_rad.get()) + _speed_at_target; // speed at transition
}
/* Either accelerate or decelerate */
if (closest_to_dest.length() < target_threshold) {
/* Vehicle is close to destination. Start to decelerate */
if (!has_reached_altitude) {
/* Altitude is not reached yet. Vehicle has to stop first before proceeding */
_speed_at_target = 0.0f;
}
float acceptance_radius = _nav_rad.get();
if (_speed_at_target < 0.01f) {
/* If vehicle wants to stop at the target, then set acceptance radius
* to zero as well.
*/
acceptance_radius = 0.0f;
}
if ((target_threshold - acceptance_radius) >= SIGMA_NORM) {
/* Slow down depending on distance to target minus acceptance radius */
float m = (speed_threshold - _speed_at_target) / (target_threshold - acceptance_radius);
speed_sp_track = m * (closest_to_dest.length() - acceptance_radius) + _speed_at_target; // speed at transition
} else {
speed_sp_track = _speed_at_target;
}
/* If we are close to target and the previous speed setpoint along track was smaller than
* current speed setpoint along track, then take over the previous one.
* This ensures smoothness since we anyway want to slow down.
*/
if ((speed_sp_prev_track < speed_sp_track)
&& (speed_sp_track * speed_sp_prev_track > 0.0f)
&& (speed_sp_prev_track > _speed_at_target)) {
speed_sp_track = speed_sp_prev_track;
}
} else {
/* Vehicle is still far from destination. Accelerate or keep maximum target speed. */
float acc_track = (speed_sp_track - speed_sp_prev_track) / _deltatime;
float yaw_diff = 0.0f;
if (PX4_ISFINITE(_yaw_wp)) {
yaw_diff = _wrap_pi(_yaw_wp - _yaw);
PX4_WARN("Yaw Waypoint not finite");
}
/* If yaw offset is large, only accelerate with 0.5 m/s^2. */
float acc_max = (fabsf(yaw_diff) > math::radians(_mis_yaw_error.get())) ? 0.5f : _acc_xy.get();
if (acc_track > acc_max) {
/* Accelerate towards target */
speed_sp_track = acc_max * _deltatime + speed_sp_prev_track;
}
}
speed_sp_track = math::constrain(speed_sp_track, 0.0f, _mc_cruise_speed);
_pos_sp_xy = closest_pt;
_vel_sp_xy = u_prev_to_dest * speed_sp_track;
}
}
void FlightTaskAutoLine::_generateAltitudeSetpoints()
{
/* Total distance between previous and target setpoint */
const float dist = fabsf(_destination(2) - _origin(2));
/* If target has not been reached, then compute setpoint depending on maximum velocity */
if ((dist > SIGMA_NORM) && (fabsf(_position(2) - _destination(2)) > 0.1f)) {
/* get various distances */
const float dist_to_prev = fabsf(_position(2) - _origin(2));
const float dist_to_target = fabsf(_destination(2) - _position(2));
/* check sign */
const bool flying_upward = _destination(2) < _position(2);
/* Speed at threshold is by default maximum speed. Threshold defines
* the point in z at which vehicle slows down to reach target altitude. */
float speed_sp = (flying_upward) ? _vel_max_up.get() : _vel_max_down.get();
/* target threshold defines the distance to target(2) at which
* the vehicle starts to slow down to approach the target smoothly */
float target_threshold = speed_sp * 1.5f;
/* If the total distance in z is NOT 2x distance of target_threshold, we
* will need to adjust the final_velocity in z */
const bool is_2_target_threshold = dist >= 2.0f * target_threshold;
const float min_vel = 0.2f; // minimum velocity: this is needed since estimation is not perfect
const float slope = (speed_sp - min_vel) / (target_threshold); /* defines the the acceleration when slowing down */
if (!is_2_target_threshold) {
/* adjust final_velocity since we are already are close
* to target and therefore it is not necessary to accelerate
* up to full speed
*/
target_threshold = dist * 0.5f;
/* get the velocity at target_threshold */
speed_sp = slope * (target_threshold) + min_vel;
}
/* we want to slow down */
if (dist_to_target < target_threshold) {
speed_sp = slope * dist_to_target + min_vel;
} else if (dist_to_prev < target_threshold) {
/* we want to accelerate */
const float acc = (speed_sp - fabsf(_vel_sp_z)) / _deltatime;
const float acc_max = (flying_upward) ? (_acc_max_up.get() * 0.5f) : (_acc_max_down.get() * 0.5f);
if (acc > acc_max) {
speed_sp = acc_max * _deltatime + fabsf(_vel_sp_z);
}
}
/* make sure vel_sp_z is always positive */
if (speed_sp < 0.0f) {
PX4_WARN("speed cannot be smaller than 0");
speed_sp = 0.0f;
}
/* get the sign of vel_sp_z */
_vel_sp_z = (flying_upward) ? -speed_sp : speed_sp;
_pos_sp_z = NAN; // We don't care about position setpoint */
} else {
/* Vehicle reached desired target altitude */
_vel_sp_z = 0.0f;
_pos_sp_z = _target(2);
}
}
void FlightTaskAutoLine::_generateVelocitySetpoints()
{
/* TODO: Remove velocity force logic from navigator, since
* navigator should only send out waypoints. */
_setPositionSetpoint(Vector3f(NAN, NAN, _position(2)));
Vector2f vel_sp_xy = Vector2f(&_velocity(0)).unit_or_zero() * _mc_cruise_speed;
_setVelocitySetpoint(Vector3f(vel_sp_xy(0), vel_sp_xy(1), NAN));
_reset();
}
float FlightTaskAutoLine::_getVelocityFromAngle(const float angle)
{
/* Minimum cruise speed when passing waypoint */
float min_cruise_speed = 0.0f;
/* Make sure that cruise speed is larger than minimum*/
if ((_mc_cruise_speed - min_cruise_speed) < SIGMA_NORM) {
return _mc_cruise_speed;
}
/* Middle cruise speed is a number between maximum cruising speed and minimum cruising speed and corresponds to speed at angle of 90degrees.
* It needs to be always larger than minimum cruise speed. */
float middle_cruise_speed = _cruise_speed_90.get();
if ((middle_cruise_speed - min_cruise_speed) < SIGMA_NORM) {
middle_cruise_speed = min_cruise_speed + SIGMA_NORM;
}
if ((_mc_cruise_speed - middle_cruise_speed) < SIGMA_NORM) {
middle_cruise_speed = (_mc_cruise_speed + min_cruise_speed) * 0.5f;
}
/* If middle cruise speed is exactly in the middle, then compute
* speed linearly
*/
bool use_linear_approach = false;
if (((_mc_cruise_speed + min_cruise_speed) * 0.5f) - middle_cruise_speed < SIGMA_NORM) {
use_linear_approach = true;
}
/* Compute speed sp at target */
float speed_close;
if (use_linear_approach) {
/* velocity close to target adjusted to angle
* vel_close = m*x+q
*/
float slope = -(_mc_cruise_speed - min_cruise_speed) / 2.0f;
speed_close = slope * angle + _mc_cruise_speed;
} else {
/* Speed close to target adjusted to angle x.
* speed_close = a *b ^x + c; where at angle x = 0 -> speed_close = cruise; angle x = 1 -> speed_close = middle_cruise_speed (this means that at 90degrees
* the velocity at target is middle_cruise_speed);
* angle x = 2 -> speed_close = min_cruising_speed */
/* from maximum cruise speed, minimum cruise speed and middle cruise speed compute constants a, b and c */
float a = -((middle_cruise_speed - _mc_cruise_speed) * (middle_cruise_speed - _mc_cruise_speed))
/ (2.0f * middle_cruise_speed - _mc_cruise_speed - min_cruise_speed);
float c = _mc_cruise_speed - a;
float b = (middle_cruise_speed - c) / a;
speed_close = a * powf(b, angle) + c;
}
/* speed_close needs to be in between max and min */
return math::constrain(speed_close, min_cruise_speed, _mc_cruise_speed);
}