Checked in L1 position and TECS altitude control. Not test-flown in HIL or outdoors yet

This commit is contained in:
Lorenz Meier
2013-09-10 11:53:59 +02:00
parent 5182860a68
commit 12e4e393bd
16 changed files with 2695 additions and 8 deletions
@@ -12,7 +12,7 @@
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name APL nor the names of its contributors may be
* 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.
*
@@ -12,7 +12,7 @@
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name APL nor the names of its contributors may be
* 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.
*
@@ -12,7 +12,7 @@
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name APL nor the names of its contributors may be
* 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.
*
@@ -12,7 +12,7 @@
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name APL nor the names of its contributors may be
* 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.
*
@@ -12,7 +12,7 @@
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name APL nor the names of its contributors may be
* 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.
*
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@@ -12,7 +12,7 @@
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name APL nor the names of its contributors may be
* 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.
*
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@@ -38,6 +38,7 @@
*/
#include <drivers/drv_hrt.h>
#include <geo/geo.h>
#define ecl_absolute_time hrt_absolute_time
#define ecl_elapsed_time hrt_elapsed_time
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/****************************************************************************
*
* 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 vector_ABove copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the vector_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 MERCHANTvector_ABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIvector_ABLE 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 LIvector_ABILITY, WHETHER IN CONTRACT, STRICT
* LIvector_ABILITY, 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_l1_pos_control.h
* Implementation of L1 position control.
* Authors and acknowledgements in header.
*
*/
#include "ecl_l1_pos_control.h"
float ECL_L1_Pos_Control::nav_roll()
{
float ret = atanf(_lateral_accel * 1.0f / CONSTANTS_ONE_G);
ret = math::constrain(ret, (-M_PI_F) / 2.0f, M_PI_F / 2.0f);
return ret;
}
float ECL_L1_Pos_Control::nav_lateral_acceleration_demand()
{
return _lateral_accel;
}
float ECL_L1_Pos_Control::nav_bearing()
{
return _wrap_pi(_nav_bearing);
}
float ECL_L1_Pos_Control::bearing_error()
{
return _bearing_error;
}
float ECL_L1_Pos_Control::target_bearing()
{
return _target_bearing;
}
float ECL_L1_Pos_Control::switch_distance(float wp_radius)
{
return math::min(wp_radius, _L1_distance);
}
bool ECL_L1_Pos_Control::reached_loiter_target(void)
{
return _circle_mode;
}
float ECL_L1_Pos_Control::crosstrack_error(void)
{
return _crosstrack_error;
}
void ECL_L1_Pos_Control::navigate_waypoints(const math::Vector2f &vector_A, const math::Vector2f &vector_B, const math::Vector2f &vector_curr_position,
const math::Vector2f &ground_speed_vector)
{
float eta;
float xtrack_vel;
float ltrack_vel;
/* get the direction between the last (visited) and next waypoint */
_target_bearing = get_bearing_to_next_waypoint(vector_curr_position.getX(), vector_curr_position.getY(), vector_B.getX(), vector_B.getY());
/* enforce a minimum ground speed of 0.1 m/s to avoid singularities */
float ground_speed = math::max(ground_speed_vector.length(), 0.1f);
/* calculate the L1 length required for the desired period */
_L1_distance = _L1_ratio * ground_speed;
/* calculate vector from A to B */
math::Vector2f vector_AB = get_local_planar_vector(vector_A, vector_B);
/*
* check if waypoints are on top of each other. If yes,
* skip A and directly continue to B
*/
if (vector_AB.length() < 1.0e-6f) {
vector_AB = get_local_planar_vector(vector_curr_position, vector_B);
}
vector_AB.normalize();
/* calculate the vector from waypoint A to the aircraft */
math::Vector2f vector_A_to_airplane = get_local_planar_vector(vector_A, vector_curr_position);
/* calculate crosstrack error (output only) */
_crosstrack_error = vector_AB % vector_A_to_airplane;
/*
* If the current position is in a +-135 degree angle behind waypoint A
* and further away from A than the L1 distance, then A becomes the L1 point.
* If the aircraft is already between A and B normal L1 logic is applied.
*/
float distance_A_to_airplane = vector_A_to_airplane.length();
float alongTrackDist = vector_A_to_airplane * vector_AB;
if (distance_A_to_airplane > _L1_distance && alongTrackDist / math::max(distance_A_to_airplane , 1.0f) < -0.7071f) {
/* calculate eta to fly to waypoint A */
/* unit vector from waypoint A to current position */
math::Vector2f vector_A_to_airplane_unit = vector_A_to_airplane.normalized();
/* velocity across / orthogonal to line */
xtrack_vel = ground_speed_vector % (-vector_A_to_airplane_unit);
/* velocity along line */
ltrack_vel = ground_speed_vector * (-vector_A_to_airplane_unit);
eta = atan2f(xtrack_vel, ltrack_vel);
/* bearing from current position to L1 point */
_nav_bearing = atan2f(-vector_A_to_airplane_unit.getY() , -vector_A_to_airplane_unit.getX());
} else {
/* calculate eta to fly along the line between A and B */
/* velocity across / orthogonal to line */
xtrack_vel = ground_speed_vector % vector_AB;
/* velocity along line */
ltrack_vel = ground_speed_vector * vector_AB;
/* calculate eta2 (angle of velocity vector relative to line) */
float eta2 = atan2f(xtrack_vel, ltrack_vel);
/* calculate eta1 (angle to L1 point) */
float xtrackErr = vector_A_to_airplane % vector_AB;
float sine_eta1 = xtrackErr / math::max(_L1_distance , 0.1f);
/* limit output to 45 degrees */
sine_eta1 = math::constrain(sine_eta1, -M_PI_F / 4.0f, +M_PI_F / 4.0f);
float eta1 = asinf(sine_eta1);
eta = eta1 + eta2;
/* bearing from current position to L1 point */
_nav_bearing = atan2f(vector_AB.getY(), vector_AB.getX()) + eta1;
}
/* limit angle to +-90 degrees */
eta = math::constrain(eta, (-M_PI_F) / 2.0f, +M_PI_F / 2.0f);
_lateral_accel = _K_L1 * ground_speed * ground_speed / _L1_distance * sinf(eta);
/* flying to waypoints, not circling them */
_circle_mode = false;
/* the bearing angle, in NED frame */
_bearing_error = eta;
}
void ECL_L1_Pos_Control::navigate_loiter(const math::Vector2f &vector_A, const math::Vector2f &vector_curr_position, float radius, int8_t loiter_direction,
const math::Vector2f &ground_speed_vector)
{
/* calculate the gains for the PD loop (circle tracking) */
float omega = (2.0f * M_PI_F / _L1_period);
float K_crosstrack = omega * omega;
float K_velocity = 2.0f * _L1_damping * omega;
/* update bearing to next waypoint */
_target_bearing = get_bearing_to_next_waypoint(vector_curr_position.getX(), vector_curr_position.getY(), vector_A.getX(), vector_A.getY());
/* ground speed, enforce minimum of 0.1 m/s to avoid singularities */
float ground_speed = math::max(ground_speed_vector.length() , 0.1f);
/* calculate the L1 length required for the desired period */
_L1_distance = _L1_ratio * ground_speed;
/* calculate the vector from waypoint A to current position */
math::Vector2f vector_A_to_airplane = get_local_planar_vector(vector_A, vector_curr_position);
/* store the normalized vector from waypoint A to current position */
math::Vector2f vector_A_to_airplane_unit = (vector_A_to_airplane).normalized();
/* calculate eta angle towards the loiter center */
/* velocity across / orthogonal to line from waypoint to current position */
float xtrack_vel_center = vector_A_to_airplane_unit % ground_speed_vector;
/* velocity along line from waypoint to current position */
float ltrack_vel_center = - (ground_speed_vector * vector_A_to_airplane_unit);
float eta = atan2f(xtrack_vel_center, ltrack_vel_center);
/* limit eta to 90 degrees */
eta = math::constrain(eta, -M_PI_F / 2.0f, +M_PI_F / 2.0f);
/* calculate the lateral acceleration to capture the center point */
float lateral_accel_sp_center = _K_L1 * ground_speed * ground_speed / _L1_distance * sinf(eta);
/* for PD control: Calculate radial position and velocity errors */
/* radial velocity error */
float xtrack_vel_circle = -ltrack_vel_center;
/* radial distance from the loiter circle (not center) */
float xtrack_err_circle = vector_A_to_airplane.length() - radius;
/* cross track error for feedback */
_crosstrack_error = xtrack_err_circle;
/* calculate PD update to circle waypoint */
float lateral_accel_sp_circle_pd = (xtrack_err_circle * K_crosstrack + xtrack_vel_circle * K_velocity);
/* calculate velocity on circle / along tangent */
float tangent_vel = xtrack_vel_center * loiter_direction;
/* prevent PD output from turning the wrong way */
if (tangent_vel < 0.0f) {
lateral_accel_sp_circle_pd = math::max(lateral_accel_sp_circle_pd , 0.0f);
}
/* calculate centripetal acceleration setpoint */
float lateral_accel_sp_circle_centripetal = tangent_vel * tangent_vel / math::max((0.5f * radius) , (radius + xtrack_err_circle));
/* add PD control on circle and centripetal acceleration for total circle command */
float lateral_accel_sp_circle = loiter_direction * (lateral_accel_sp_circle_pd + lateral_accel_sp_circle_centripetal);
/*
* Switch between circle (loiter) and capture (towards waypoint center) mode when
* the commands switch over. Only fly towards waypoint if outside the circle.
*/
// XXX check switch over
if ((lateral_accel_sp_center < lateral_accel_sp_circle && loiter_direction > 0 && xtrack_err_circle > 0.0f) |
(lateral_accel_sp_center > lateral_accel_sp_circle && loiter_direction < 0 && xtrack_err_circle > 0.0f)) {
_lateral_accel = lateral_accel_sp_center;
_circle_mode = false;
/* angle between requested and current velocity vector */
_bearing_error = eta;
/* bearing from current position to L1 point */
_nav_bearing = atan2f(-vector_A_to_airplane_unit.getY() , -vector_A_to_airplane_unit.getX());
} else {
_lateral_accel = lateral_accel_sp_circle;
_circle_mode = true;
_bearing_error = 0.0f;
/* bearing from current position to L1 point */
_nav_bearing = atan2f(-vector_A_to_airplane_unit.getY() , -vector_A_to_airplane_unit.getX());
}
}
void ECL_L1_Pos_Control::navigate_heading(float navigation_heading, float current_heading, const math::Vector2f &ground_speed_vector)
{
float eta;
/*
* As the commanded heading is the only reference
* (and no crosstrack correction occurs),
* target and navigation bearing become the same
*/
_target_bearing = _nav_bearing = _wrap_pi(navigation_heading);
eta = _target_bearing - _wrap_pi(current_heading);
eta = _wrap_pi(eta);
/* consequently the bearing error is exactly eta: */
_bearing_error = eta;
/* ground speed is the length of the ground speed vector */
float ground_speed = ground_speed_vector.length();
/* adjust L1 distance to keep constant frequency */
_L1_distance = ground_speed / _heading_omega;
float omega_vel = ground_speed * _heading_omega;
/* not circling a waypoint */
_circle_mode = false;
/* navigating heading means by definition no crosstrack error */
_crosstrack_error = 0;
/* limit eta to 90 degrees */
eta = math::constrain(eta, (-M_PI_F) / 2.0f, +M_PI_F / 2.0f);
_lateral_accel = 2.0f * sinf(eta) * omega_vel;
}
void ECL_L1_Pos_Control::navigate_level_flight(float current_heading)
{
/* reset all heading / error measures resulting in zero roll */
_target_bearing = current_heading;
_nav_bearing = current_heading;
_bearing_error = 0;
_crosstrack_error = 0;
_lateral_accel = 0;
/* not circling a waypoint when flying level */
_circle_mode = false;
}
math::Vector2f ECL_L1_Pos_Control::get_local_planar_vector(const math::Vector2f &origin, const math::Vector2f &target) const
{
math::Vector2f out;
out.setX(math::radians((target.getX() - origin.getX())));
out.setY(math::radians((target.getY() - origin.getY())*cosf(math::radians(origin.getX()))));
return out * static_cast<float>(CONSTANTS_RADIUS_OF_EARTH);
}
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/****************************************************************************
*
* 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_l1_pos_control.h
* Implementation of L1 position control.
*
* @author Lorenz Meier
*
* Acknowledgements and References:
*
* Original publication:
* S. Park, J. Deyst, and J. P. How, "A New Nonlinear Guidance Logic for Trajectory Tracking,"
* Proceedings of the AIAA Guidance, Navigation and Control
* Conference, Aug 2004. AIAA-2004-4900.
*
* Original navigation logic modified by Paul Riseborough 2013:
* - Explicit control over frequency and damping
* - Explicit control over track capture angle
* - Ability to use loiter radius smaller than L1 length
* - Modified to use PD control for circle tracking to enable loiter radius less than L1 length
* - Modified to enable period and damping of guidance loop to be set explicitly
* - Modified to provide explicit control over capture angle
*
*/
#ifndef ECL_L1_POS_CONTROL_H
#define ECL_L1_POS_CONTROL_H
#include <mathlib/mathlib.h>
#include <geo/geo.h>
#include <ecl/ecl.h>
/**
* L1 Nonlinear Guidance Logic
*/
class __EXPORT ECL_L1_Pos_Control
{
public:
ECL_L1_Pos_Control() {
_L1_period = 25;
_L1_damping = 0.75f;
}
/**
* The current target bearing
*
* @return bearing angle (-pi..pi, in NED frame)
*/
float nav_bearing();
/**
* Get lateral acceleration demand.
*
* @return Lateral acceleration in m/s^2
*/
float nav_lateral_acceleration_demand();
// return the heading error angle +ve to left of track
/**
* Heading error.
*
* The heading error is either compared to the current track
* or to the tangent of the current loiter radius.
*/
float bearing_error();
/**
* Bearing from aircraft to current target.
*
* @return bearing angle (-pi..pi, in NED frame)
*/
float target_bearing();
/**
* Get roll angle setpoint for fixed wing.
*
* @return Roll angle (in NED frame)
*/
float nav_roll();
/**
* Get the current crosstrack error.
*
* @return Crosstrack error in meters.
*/
float crosstrack_error();
/**
* Returns true if the loiter waypoint has been reached
*/
bool reached_loiter_target();
/**
* Get the switch distance
*
* This is the distance at which the system will
* switch to the next waypoint. This depends on the
* period and damping
*
* @param waypoint_switch_radius The switching radius the waypoint has set.
*/
float switch_distance(float waypoint_switch_radius);
/**
* Navigate between two waypoints
*
* Calling this function with two waypoints results in the
* control outputs to fly to the line segment defined by
* the points and once captured following the line segment.
*
* @return sets _lateral_accel setpoint
*/
void navigate_waypoints(const math::Vector2f &vector_A, const math::Vector2f &vector_B, const math::Vector2f &vector_curr_position,
const math::Vector2f &ground_speed);
/**
* Navigate on an orbit around a loiter waypoint.
*
* @return sets _lateral_accel setpoint
*/
void navigate_loiter(const math::Vector2f &vector_A, const math::Vector2f &vector_curr_position, float radius, int8_t loiter_direction,
const math::Vector2f &ground_speed_vector);
/**
* Navigate on a fixed bearing.
*
* This only holds a certain direction and does not perform cross
* track correction.
*
* @return sets _lateral_accel setpoint
*/
void navigate_heading(float navigation_heading, float current_heading, const math::Vector2f &ground_speed);
/**
* Keep the wings level
*/
void navigate_level_flight(float current_heading);
/**
* Set the L1 period.
*/
void set_l1_period(float period) {
_L1_period = period;
_L1_ratio = 1.0f / M_PI_F * _L1_damping * _L1_period;
/* calculate normalized frequency for heading tracking */
_heading_omega = sqrtf(2.0f) * M_PI_F / _L1_period;
}
/**
* Set the L1 damping factor.
*
* The original publication recommends a default of sqrt(2) / 2 = 0.707
*/
void set_l1_damping(float damping) {
_L1_damping = damping;
_L1_ratio = 1.0f / M_PI_F * _L1_damping * _L1_period;
_K_L1 = 4.0f * _L1_damping * _L1_damping;
}
private:
float _lateral_accel; ///< Lateral acceleration setpoint in m/s^2
float _L1_distance; ///< L1 lead distance, defined by period and damping
bool _circle_mode; ///< flag for loiter mode
float _nav_bearing; ///< bearing to L1 reference point
float _bearing_error; ///< bearing error
float _crosstrack_error; ///< crosstrack error in meters
float _target_bearing; ///< the heading setpoint
float _L1_period; ///< L1 tracking period in seconds
float _L1_damping; ///< L1 damping ratio
float _L1_ratio; ///< L1 ratio for navigation
float _K_L1; ///< L1 control gain for _L1_damping
float _heading_omega; ///< Normalized frequency
/**
* Convert a 2D vector from WGS84 to planar coordinates.
*
* This converts from latitude and longitude to planar
* coordinates with (0,0) being at the position of ref and
* returns a vector in meters towards wp.
*
* @param ref The reference position in WGS84 coordinates
* @param wp The point to convert to into the local coordinates, in WGS84 coordinates
* @return The vector in meters pointing from the reference position to the coordinates
*/
math::Vector2f get_local_planar_vector(const math::Vector2f &origin, const math::Vector2f &target) const;
};
#endif /* ECL_L1_POS_CONTROL_H */
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#
SRCS = attitude_fw/ecl_pitch_controller.cpp \
attitude_fw/ecl_roll_controller.cpp \
attitude_fw/ecl_yaw_controller.cpp
attitude_fw/ecl_roll_controller.cpp \
attitude_fw/ecl_yaw_controller.cpp \
l1/ecl_l1_pos_control.cpp