/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
#include "AC_Avoid.h"
#include // AHRS library
#include // Failsafe fence library
#include
#include
#include
#include
#if APM_BUILD_TYPE(APM_BUILD_Rover)
# define AP_AVOID_BEHAVE_DEFAULT AC_Avoid::BehaviourType::BEHAVIOR_STOP
#else
# define AP_AVOID_BEHAVE_DEFAULT AC_Avoid::BehaviourType::BEHAVIOR_SLIDE
#endif
#if APM_BUILD_TYPE(APM_BUILD_ArduCopter)
# define AP_AVOID_ENABLE_Z 1
#endif
const AP_Param::GroupInfo AC_Avoid::var_info[] = {
// @Param: ENABLE
// @DisplayName: Avoidance control enable/disable
// @Description: Enabled/disable avoidance input sources
// @Values: 0:None,1:UseFence,2:UseProximitySensor,3:UseFence and UseProximitySensor,4:UseBeaconFence,7:All
// @Bitmask: 0:UseFence,1:UseProximitySensor,2:UseBeaconFence
// @User: Standard
AP_GROUPINFO_FLAGS("ENABLE", 1, AC_Avoid, _enabled, AC_AVOID_DEFAULT, AP_PARAM_FLAG_ENABLE),
// @Param{Copter}: ANGLE_MAX
// @DisplayName: Avoidance max lean angle in non-GPS flight modes
// @Description: Max lean angle used to avoid obstacles while in non-GPS modes
// @Units: cdeg
// @Range: 0 4500
// @User: Standard
AP_GROUPINFO_FRAME("ANGLE_MAX", 2, AC_Avoid, _angle_max, 1000, AP_PARAM_FRAME_COPTER | AP_PARAM_FRAME_HELI | AP_PARAM_FRAME_TRICOPTER),
// @Param{Copter}: DIST_MAX
// @DisplayName: Avoidance distance maximum in non-GPS flight modes
// @Description: Distance from object at which obstacle avoidance will begin in non-GPS modes
// @Units: m
// @Range: 1 30
// @User: Standard
AP_GROUPINFO_FRAME("DIST_MAX", 3, AC_Avoid, _dist_max, AC_AVOID_NONGPS_DIST_MAX_DEFAULT, AP_PARAM_FRAME_COPTER | AP_PARAM_FRAME_HELI | AP_PARAM_FRAME_TRICOPTER),
// @Param: MARGIN
// @DisplayName: Avoidance distance margin in GPS modes
// @Description: Vehicle will attempt to stay at least this distance (in meters) from objects while in GPS modes
// @Units: m
// @Range: 1 10
// @User: Standard
AP_GROUPINFO("MARGIN", 4, AC_Avoid, _margin, 2.0f),
// @Param{Copter}: BEHAVE
// @DisplayName: Avoidance behaviour
// @Description: Avoidance behaviour (slide or stop)
// @Values: 0:Slide,1:Stop
// @User: Standard
AP_GROUPINFO_FRAME("BEHAVE", 5, AC_Avoid, _behavior, AP_AVOID_BEHAVE_DEFAULT, AP_PARAM_FRAME_COPTER | AP_PARAM_FRAME_HELI | AP_PARAM_FRAME_TRICOPTER),
// @Param: BACKUP_SPD
// @DisplayName: Avoidance maximum backup speed
// @Description: Maximum speed that will be used to back away from obstacles in GPS modes (m/s). Set zero to disable
// @Units: m/s
// @Range: 0 2
// @User: Standard
AP_GROUPINFO("BACKUP_SPD", 6, AC_Avoid, _backup_speed_max, 0.75f),
// @Param: ALT_MIN
// @DisplayName: Avoidance minimum altitude
// @Description: Minimum altitude above which proximity based avoidance will start working. This requires a valid downward facing rangefinder reading to work. Set zero to disable
// @Units: m
// @Range: 0 6
// @User: Standard
AP_GROUPINFO("ALT_MIN", 7, AC_Avoid, _alt_min, 0.0f),
// @Param: ACCEL_MAX
// @DisplayName: Avoidance maximum acceleration
// @Description: Maximum acceleration with which obstacles will be avoided with. Set zero to disable acceleration limits
// @Units: m/s/s
// @Range: 0 9
// @User: Standard
AP_GROUPINFO("ACCEL_MAX", 8, AC_Avoid, _accel_max, 3.0f),
AP_GROUPEND
};
/// Constructor
AC_Avoid::AC_Avoid()
{
_singleton = this;
AP_Param::setup_object_defaults(this, var_info);
}
/*
* This method limits velocity and calculates backaway velocity from various supported fences
* Also limits vertical velocity using adjust_velocity_z method
*/
void AC_Avoid::adjust_velocity_fence(float kP, float accel_cmss, Vector3f &desired_vel_cms, Vector3f &backup_vel, float kP_z, float accel_cmss_z, float dt)
{
// Only horizontal component needed for most fences, since fences are 2D
Vector2f desired_velocity_xy_cms{desired_vel_cms.x, desired_vel_cms.y};
// limit acceleration
const float accel_cmss_limited = MIN(accel_cmss, AC_AVOID_ACCEL_CMSS_MAX);
// maximum component of desired backup velocity in each quadrant
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
if ((_enabled & AC_AVOID_STOP_AT_FENCE) > 0) {
// Store velocity needed to back away from fence
Vector2f backup_vel_fence;
adjust_velocity_circle_fence(kP, accel_cmss_limited, desired_velocity_xy_cms, backup_vel_fence, dt);
find_max_quadrant_velocity(backup_vel_fence, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
// backup_vel_fence is set to zero after each fence incase the velocity is unset from previous methods
backup_vel_fence.zero();
adjust_velocity_inclusion_and_exclusion_polygons(kP, accel_cmss_limited, desired_velocity_xy_cms, backup_vel_fence, dt);
find_max_quadrant_velocity(backup_vel_fence, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
backup_vel_fence.zero();
adjust_velocity_inclusion_circles(kP, accel_cmss_limited, desired_velocity_xy_cms, backup_vel_fence, dt);
find_max_quadrant_velocity(backup_vel_fence, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
backup_vel_fence.zero();
adjust_velocity_exclusion_circles(kP, accel_cmss_limited, desired_velocity_xy_cms, backup_vel_fence, dt);
find_max_quadrant_velocity(backup_vel_fence, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
}
if ((_enabled & AC_AVOID_STOP_AT_BEACON_FENCE) > 0) {
// Store velocity needed to back away from beacon fence
Vector2f backup_vel_beacon;
adjust_velocity_beacon_fence(kP, accel_cmss_limited, desired_velocity_xy_cms, backup_vel_beacon, dt);
find_max_quadrant_velocity(backup_vel_beacon, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
}
// check for vertical fence
float desired_velocity_z_cms = desired_vel_cms.z;
float desired_backup_vel_z = 0.0f;
adjust_velocity_z(kP_z, accel_cmss_z, desired_velocity_z_cms, desired_backup_vel_z, dt);
// Desired backup velocity is sum of maximum velocity component in each quadrant
const Vector2f desired_backup_vel_xy = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
backup_vel = Vector3f{desired_backup_vel_xy.x, desired_backup_vel_xy.y, desired_backup_vel_z};
desired_vel_cms = Vector3f{desired_velocity_xy_cms.x, desired_velocity_xy_cms.y, desired_velocity_z_cms};
}
/*
* Adjusts the desired velocity so that the vehicle can stop
* before the fence/object.
* kP, accel_cmss are for the horizontal axis
* kP_z, accel_cmss_z are for vertical axis
*/
void AC_Avoid::adjust_velocity(Vector3f &desired_vel_cms, bool &backing_up, float kP, float accel_cmss, float kP_z, float accel_cmss_z, float dt)
{
// exit immediately if disabled
if (_enabled == AC_AVOID_DISABLED) {
return;
}
// make a copy of input velocity, because desired_vel_cms might be changed
const Vector3f desired_vel_cms_original = desired_vel_cms;
// limit acceleration
const float accel_cmss_limited = MIN(accel_cmss, AC_AVOID_ACCEL_CMSS_MAX);
// maximum component of horizontal desired backup velocity in each quadrant
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
float back_vel_up = 0.0f;
float back_vel_down = 0.0f;
// Avoidance in response to proximity sensor
if ((_enabled & AC_AVOID_USE_PROXIMITY_SENSOR) > 0 && _proximity_enabled && _proximity_alt_enabled) {
// Store velocity needed to back away from physical obstacles
Vector3f backup_vel_proximity;
adjust_velocity_proximity(kP, accel_cmss_limited, desired_vel_cms, backup_vel_proximity, kP_z,accel_cmss_z, dt);
find_max_quadrant_velocity_3D(backup_vel_proximity, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, back_vel_up, back_vel_down);
}
// Avoidance in response to various fences
Vector3f backup_vel_fence;
adjust_velocity_fence(kP, accel_cmss, desired_vel_cms, backup_vel_fence, kP_z, accel_cmss_z, dt);
find_max_quadrant_velocity_3D(backup_vel_fence , quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, back_vel_up, back_vel_down);
// Desired backup velocity is sum of maximum velocity component in each quadrant
const Vector2f desired_backup_vel_xy = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
const float desired_backup_vel_z = back_vel_down + back_vel_up;
Vector3f desired_backup_vel{desired_backup_vel_xy.x, desired_backup_vel_xy.y, desired_backup_vel_z};
const float max_back_spd_cms = _backup_speed_max * 100.0f;
if (!desired_backup_vel.is_zero() && is_positive(max_back_spd_cms)) {
backing_up = true;
// Constrain backing away speed
if (desired_backup_vel.length() > max_back_spd_cms) {
desired_backup_vel = desired_backup_vel.normalized() * max_back_spd_cms;
}
// let user take control if they are backing away at a greater speed than what we have calculated
// this has to be done for x,y,z seperately. For eg, user is doing fine in "x" direction but might need backing up in "y".
if (!is_zero(desired_backup_vel.x)) {
if (is_positive(desired_backup_vel.x)) {
desired_vel_cms.x = MAX(desired_vel_cms.x, desired_backup_vel.x);
} else {
desired_vel_cms.x = MIN(desired_vel_cms.x, desired_backup_vel.x);
}
}
if (!is_zero(desired_backup_vel.y)) {
if (is_positive(desired_backup_vel.y)) {
desired_vel_cms.y = MAX(desired_vel_cms.y, desired_backup_vel.y);
} else {
desired_vel_cms.y = MIN(desired_vel_cms.y, desired_backup_vel.y);
}
}
if (!is_zero(desired_backup_vel.z)) {
if (is_positive(desired_backup_vel.z)) {
desired_vel_cms.z = MAX(desired_vel_cms.z, desired_backup_vel.z);
} else {
desired_vel_cms.z = MIN(desired_vel_cms.z, desired_backup_vel.z);
}
}
}
// limit acceleration
limit_accel(desired_vel_cms_original, desired_vel_cms, dt);
if (desired_vel_cms_original != desired_vel_cms) {
_last_limit_time = AP_HAL::millis();
}
if (limits_active()) {
// log at not more than 10hz (adjust_velocity method can be potentially called at 400hz!)
uint32_t now = AP_HAL::millis();
if ((now - _last_log_ms) > 100) {
_last_log_ms = now;
Write_SimpleAvoidance(true, desired_vel_cms_original, desired_vel_cms, backing_up);
}
} else {
// avoidance isn't active anymore
// log once so that it registers in logs
if (_last_log_ms) {
Write_SimpleAvoidance(false, desired_vel_cms_original, desired_vel_cms, backing_up);
// this makes sure logging won't run again till it is active
_last_log_ms = 0;
}
}
}
/*
* Limit acceleration so that change of velocity output by avoidance library is controlled
* This helps reduce jerks and sudden movements in the vehicle
*/
void AC_Avoid::limit_accel(const Vector3f &original_vel, Vector3f &modified_vel, float dt)
{
if (original_vel == modified_vel || is_zero(_accel_max) || !is_positive(dt)) {
// we can't limit accel if any of these conditions are true
return;
}
if (AP_HAL::millis() - _last_limit_time > AC_AVOID_ACCEL_TIMEOUT_MS) {
// reset this velocity because its been a long time since avoidance was active
_prev_avoid_vel = original_vel;
}
// acceleration demanded by avoidance
const Vector3f accel = (modified_vel - _prev_avoid_vel)/dt;
// max accel in cm
const float max_accel_cm = _accel_max * 100.0f;
if (accel.length() > max_accel_cm) {
// pull back on the acceleration
const Vector3f accel_direction = accel.normalized();
modified_vel = (accel_direction * max_accel_cm) * dt + _prev_avoid_vel;
}
_prev_avoid_vel = modified_vel;
return;
}
// This method is used in most Rover modes and not in Copter
// adjust desired horizontal speed so that the vehicle stops before the fence or object
// accel (maximum acceleration/deceleration) is in m/s/s
// heading is in radians
// speed is in m/s
// kP should be zero for linear response, non-zero for non-linear response
void AC_Avoid::adjust_speed(float kP, float accel, float heading, float &speed, float dt)
{
// convert heading and speed into velocity vector
Vector3f vel{
cosf(heading) * speed * 100.0f,
sinf(heading) * speed * 100.0f,
0.0f
};
bool backing_up = false;
adjust_velocity(vel, backing_up, kP, accel * 100.0f, 0, 0, dt);
const Vector2f vel_xy{vel.x, vel.y};
if (backing_up) {
// back up
if (fabsf(wrap_180(degrees(vel_xy.angle())) - degrees(heading)) > 90.0f) {
// Big difference between the direction of velocity vector and actual heading therefore we need to reverse the direction
speed = -vel_xy.length() * 0.01f;
} else {
speed = vel_xy.length() * 0.01f;
}
return;
}
// No need to back up so adjust speed towards zero if needed
if (is_negative(speed)) {
speed = -vel_xy.length() * 0.01f;
} else {
speed = vel_xy.length() * 0.01f;
}
}
// adjust vertical climb rate so vehicle does not break the vertical fence
void AC_Avoid::adjust_velocity_z(float kP, float accel_cmss, float& climb_rate_cms, float& backup_speed, float dt)
{
#ifdef AP_AVOID_ENABLE_Z
// exit immediately if disabled
if (_enabled == AC_AVOID_DISABLED) {
return;
}
// do not adjust climb_rate if level or descending
if (climb_rate_cms <= 0.0f) {
return;
}
// limit acceleration
const float accel_cmss_limited = MIN(accel_cmss, AC_AVOID_ACCEL_CMSS_MAX);
bool limit_alt = false;
float alt_diff = 0.0f; // distance from altitude limit to vehicle in metres (positive means vehicle is below limit)
const AP_AHRS &_ahrs = AP::ahrs();
// calculate distance below fence
AC_Fence *fence = AP::fence();
if ((_enabled & AC_AVOID_STOP_AT_FENCE) > 0 && fence && (fence->get_enabled_fences() & AC_FENCE_TYPE_ALT_MAX) > 0) {
// calculate distance from vehicle to safe altitude
float veh_alt;
_ahrs.get_relative_position_D_home(veh_alt);
// _fence.get_safe_alt_max() is UP, veh_alt is DOWN:
alt_diff = fence->get_safe_alt_max() + veh_alt;
limit_alt = true;
}
// calculate distance to (e.g.) optical flow altitude limit
// AHRS values are always in metres
float alt_limit;
float curr_alt;
if (_ahrs.get_hgt_ctrl_limit(alt_limit) &&
_ahrs.get_relative_position_D_origin(curr_alt)) {
// alt_limit is UP, curr_alt is DOWN:
const float ctrl_alt_diff = alt_limit + curr_alt;
if (!limit_alt || ctrl_alt_diff < alt_diff) {
alt_diff = ctrl_alt_diff;
limit_alt = true;
}
}
#if HAL_PROXIMITY_ENABLED
// get distance from proximity sensor
float proximity_alt_diff;
AP_Proximity *proximity = AP::proximity();
if (proximity && proximity->get_upward_distance(proximity_alt_diff)) {
proximity_alt_diff -= _margin;
if (!limit_alt || proximity_alt_diff < alt_diff) {
alt_diff = proximity_alt_diff;
limit_alt = true;
}
}
#endif
// limit climb rate
if (limit_alt) {
// do not allow climbing if we've breached the safe altitude
if (alt_diff <= 0.0f) {
climb_rate_cms = MIN(climb_rate_cms, 0.0f);
// also calculate backup speed that will get us back to safe altitude
backup_speed = -1*(get_max_speed(kP, accel_cmss_limited, -alt_diff*100.0f, dt));
return;
}
// limit climb rate
const float max_speed = get_max_speed(kP, accel_cmss_limited, alt_diff*100.0f, dt);
climb_rate_cms = MIN(max_speed, climb_rate_cms);
}
# endif
}
// adjust roll-pitch to push vehicle away from objects
// roll and pitch value are in centi-degrees
void AC_Avoid::adjust_roll_pitch(float &roll, float &pitch, float veh_angle_max)
{
// exit immediately if proximity based avoidance is disabled
if ((_enabled & AC_AVOID_USE_PROXIMITY_SENSOR) == 0 || !_proximity_enabled) {
return;
}
// exit immediately if angle max is zero
if (_angle_max <= 0.0f || veh_angle_max <= 0.0f) {
return;
}
float roll_positive = 0.0f; // maximum positive roll value
float roll_negative = 0.0f; // minimum negative roll value
float pitch_positive = 0.0f; // maximum positive pitch value
float pitch_negative = 0.0f; // minimum negative pitch value
// get maximum positive and negative roll and pitch percentages from proximity sensor
get_proximity_roll_pitch_pct(roll_positive, roll_negative, pitch_positive, pitch_negative);
// add maximum positive and negative percentages together for roll and pitch, convert to centi-degrees
Vector2f rp_out((roll_positive + roll_negative) * 4500.0f, (pitch_positive + pitch_negative) * 4500.0f);
// apply avoidance angular limits
// the object avoidance lean angle is never more than 75% of the total angle-limit to allow the pilot to override
const float angle_limit = constrain_float(_angle_max, 0.0f, veh_angle_max * AC_AVOID_ANGLE_MAX_PERCENT);
float vec_len = rp_out.length();
if (vec_len > angle_limit) {
rp_out *= (angle_limit / vec_len);
}
// add passed in roll, pitch angles
rp_out.x += roll;
rp_out.y += pitch;
// apply total angular limits
vec_len = rp_out.length();
if (vec_len > veh_angle_max) {
rp_out *= (veh_angle_max / vec_len);
}
// return adjusted roll, pitch
roll = rp_out.x;
pitch = rp_out.y;
}
/*
* Note: This method is used to limit velocity horizontally only
* Limits the component of desired_vel_cms in the direction of the unit vector
* limit_direction to be at most the maximum speed permitted by the limit_distance_cm.
*
* Uses velocity adjustment idea from Randy's second email on this thread:
* https://groups.google.com/forum/#!searchin/drones-discuss/obstacle/drones-discuss/QwUXz__WuqY/qo3G8iTLSJAJ
*/
void AC_Avoid::limit_velocity_2D(float kP, float accel_cmss, Vector2f &desired_vel_cms, const Vector2f& limit_direction, float limit_distance_cm, float dt)
{
const float max_speed = get_max_speed(kP, accel_cmss, limit_distance_cm, dt);
// project onto limit direction
const float speed = desired_vel_cms * limit_direction;
if (speed > max_speed) {
// subtract difference between desired speed and maximum acceptable speed
desired_vel_cms += limit_direction*(max_speed - speed);
}
}
/*
* Note: This method is used to limit velocity horizontally and vertically given a 3D desired velocity vector
* Limits the component of desired_vel_cms in the direction of the obstacle_vector based on the passed value of "margin"
*/
void AC_Avoid::limit_velocity_3D(float kP, float accel_cmss, Vector3f &desired_vel_cms, const Vector3f& obstacle_vector, float margin_cm, float kP_z, float accel_cmss_z, float dt)
{
if (desired_vel_cms.is_zero()) {
// nothing to limit
return;
}
// create a margin_cm length vector in the direction of desired_vel_cms
// this will create larger margin towards the direction vehicle is traveling in
const Vector3f margin_vector = desired_vel_cms.normalized() * margin_cm;
const Vector2f limit_direction_xy{obstacle_vector.x, obstacle_vector.y};
if (!limit_direction_xy.is_zero()) {
const float distance_from_fence_xy = MAX((limit_direction_xy.length() - Vector2f{margin_vector.x, margin_vector.y}.length()), 0.0f);
Vector2f velocity_xy{desired_vel_cms.x, desired_vel_cms.y};
limit_velocity_2D(kP, accel_cmss, velocity_xy, limit_direction_xy.normalized(), distance_from_fence_xy, dt);
desired_vel_cms.x = velocity_xy.x;
desired_vel_cms.y = velocity_xy.y;
}
if (is_zero(desired_vel_cms.z) || is_zero(obstacle_vector.z)) {
// nothing to limit vertically if desired_vel_cms.z is zero
// if obstacle_vector.z is zero then the obstacle is probably horizontally located, and we can move vertically
return;
}
if (is_positive(desired_vel_cms.z) != is_positive(obstacle_vector.z)) {
// why limit velocity vertically when we are going the opposite direction
return;
}
// to check if Z velocity changes
const float velocity_z_original = desired_vel_cms.z;
const float z_speed = fabsf(desired_vel_cms.z);
// obstacle_vector.z and margin_vector.z should be in same direction as checked above
const float dist_z = MAX(fabsf(obstacle_vector.z) - fabsf(margin_vector.z), 0.0f);
if (is_zero(dist_z)) {
// eliminate any vertical velocity
desired_vel_cms.z = 0.0f;
} else {
const float max_z_speed = get_max_speed(kP_z, accel_cmss_z, dist_z, dt);
desired_vel_cms.z = MIN(max_z_speed, z_speed);
}
// make sure the direction of the Z velocity did not change
// we are only limiting speed here, not changing directions
// check if original z velocity is positive or negative
if (is_negative(velocity_z_original)) {
desired_vel_cms.z = desired_vel_cms.z * -1.0f;
}
}
/*
* Compute the back away horizontal velocity required to avoid breaching margin
* INPUT: This method requires the breach in margin distance (back_distance_cm), direction towards the breach (limit_direction)
* It then calculates the desired backup velocity and passes it on to "find_max_quadrant_velocity" method to distribute the velocity vectors into respective quadrants
* OUTPUT: The method then outputs four velocities (quad1/2/3/4_back_vel_cms), which correspond to the maximum horizontal desired backup velocity in each quadrant
*/
void AC_Avoid::calc_backup_velocity_2D(float kP, float accel_cmss, Vector2f &quad1_back_vel_cms, Vector2f &quad2_back_vel_cms, Vector2f &quad3_back_vel_cms, Vector2f &quad4_back_vel_cms, float back_distance_cm, Vector2f limit_direction, float dt)
{
if (limit_direction.is_zero()) {
// protect against divide by zero
return;
}
// speed required to move away the exact distance that we have breached the margin with
const float back_speed = get_max_speed(kP, 0.4f * accel_cmss, fabsf(back_distance_cm), dt);
// direction to the obstacle
limit_direction.normalize();
// move in the opposite direction with the required speed
Vector2f back_direction_vel = limit_direction * (-back_speed);
// divide the vector into quadrants, find maximum velocity component in each quadrant
find_max_quadrant_velocity(back_direction_vel, quad1_back_vel_cms, quad2_back_vel_cms, quad3_back_vel_cms, quad4_back_vel_cms);
}
/*
* Compute the back away velocity required to avoid breaching margin, including vertical component
* min_z_vel is <= 0, and stores the greatest velocity in the downwards direction
* max_z_vel is >= 0, and stores the greatest velocity in the upwards direction
* eventually max_z_vel + min_z_vel will give the final desired Z backaway velocity
*/
void AC_Avoid::calc_backup_velocity_3D(float kP, float accel_cmss, Vector2f &quad1_back_vel_cms, Vector2f &quad2_back_vel_cms, Vector2f &quad3_back_vel_cms, Vector2f &quad4_back_vel_cms, float back_distance_cms, Vector3f limit_direction, float kp_z, float accel_cmss_z, float back_distance_z, float& min_z_vel, float& max_z_vel, float dt)
{
// backup horizontally
if (is_positive(back_distance_cms)) {
Vector2f limit_direction_2d{limit_direction.x, limit_direction.y};
calc_backup_velocity_2D(kP, accel_cmss, quad1_back_vel_cms, quad2_back_vel_cms, quad3_back_vel_cms, quad4_back_vel_cms, back_distance_cms, limit_direction_2d, dt);
}
// backup vertically
if (!is_zero(back_distance_z)) {
float back_speed_z = get_max_speed(kp_z, 0.4f * accel_cmss_z, fabsf(back_distance_z), dt);
// Down is positive
if (is_positive(back_distance_z)) {
back_speed_z *= -1.0f;
}
// store the z backup speed into min or max z if possible
if (back_speed_z < min_z_vel) {
min_z_vel = back_speed_z;
}
if (back_speed_z > max_z_vel) {
max_z_vel = back_speed_z;
}
}
}
/*
* Calculate maximum velocity vector that can be formed in each quadrant
* This method takes the desired backup velocity, and four other velocities corresponding to each quadrant
* The desired velocity is then fit into one of the 4 quadrant velocities as per the sign of its components
* This ensures that if we have multiple backup velocities, we can get the maximum of all of those velocities in each quadrant
*/
void AC_Avoid::find_max_quadrant_velocity(Vector2f &desired_vel, Vector2f &quad1_vel, Vector2f &quad2_vel, Vector2f &quad3_vel, Vector2f &quad4_vel)
{
if (desired_vel.is_zero()) {
return;
}
// first quadrant: +ve x, +ve y direction
if (is_positive(desired_vel.x) && is_positive(desired_vel.y)) {
quad1_vel = Vector2f{MAX(quad1_vel.x, desired_vel.x), MAX(quad1_vel.y,desired_vel.y)};
}
// second quadrant: -ve x, +ve y direction
if (is_negative(desired_vel.x) && is_positive(desired_vel.y)) {
quad2_vel = Vector2f{MIN(quad2_vel.x, desired_vel.x), MAX(quad2_vel.y,desired_vel.y)};
}
// third quadrant: -ve x, -ve y direction
if (is_negative(desired_vel.x) && is_negative(desired_vel.y)) {
quad3_vel = Vector2f{MIN(quad3_vel.x, desired_vel.x), MIN(quad3_vel.y,desired_vel.y)};
}
// fourth quadrant: +ve x, -ve y direction
if (is_positive(desired_vel.x) && is_negative(desired_vel.y)) {
quad4_vel = Vector2f{MAX(quad4_vel.x, desired_vel.x), MIN(quad4_vel.y,desired_vel.y)};
}
}
/*
Calculate maximum velocity vector that can be formed in each quadrant and separately store max & min of vertical components
*/
void AC_Avoid::find_max_quadrant_velocity_3D(Vector3f &desired_vel, Vector2f &quad1_vel, Vector2f &quad2_vel, Vector2f &quad3_vel, Vector2f &quad4_vel, float &max_z_vel, float &min_z_vel)
{
// split into horizontal and vertical components
Vector2f velocity_xy{desired_vel.x, desired_vel.y};
find_max_quadrant_velocity(velocity_xy, quad1_vel, quad2_vel, quad3_vel, quad4_vel);
// store maximum and minimum of z
if (is_positive(desired_vel.z) && (desired_vel.z > max_z_vel)) {
max_z_vel = desired_vel.z;
}
if (is_negative(desired_vel.z) && (desired_vel.z < min_z_vel)) {
min_z_vel = desired_vel.z;
}
}
/*
* Computes the speed such that the stopping distance
* of the vehicle will be exactly the input distance.
*/
float AC_Avoid::get_max_speed(float kP, float accel_cmss, float distance_cm, float dt) const
{
if (is_zero(kP)) {
return safe_sqrt(2.0f * distance_cm * accel_cmss);
} else {
return sqrt_controller(distance_cm, kP, accel_cmss, dt);
}
}
/*
* Adjusts the desired velocity for the circular fence.
*/
void AC_Avoid::adjust_velocity_circle_fence(float kP, float accel_cmss, Vector2f &desired_vel_cms, Vector2f &backup_vel, float dt)
{
AC_Fence *fence = AP::fence();
if (fence == nullptr) {
return;
}
AC_Fence &_fence = *fence;
// exit if circular fence is not enabled
if ((_fence.get_enabled_fences() & AC_FENCE_TYPE_CIRCLE) == 0) {
return;
}
// exit if the circular fence has already been breached
if ((_fence.get_breaches() & AC_FENCE_TYPE_CIRCLE) != 0) {
return;
}
// get desired speed
const float desired_speed = desired_vel_cms.length();
if (is_zero(desired_speed)) {
// no avoidance necessary when desired speed is zero
return;
}
const AP_AHRS &_ahrs = AP::ahrs();
// get position as a 2D offset from ahrs home
Vector2f position_xy;
if (!_ahrs.get_relative_position_NE_home(position_xy)) {
// we have no idea where we are....
return;
}
position_xy *= 100.0f; // m -> cm
// get the fence radius in cm
const float fence_radius = _fence.get_radius() * 100.0f;
// get the margin to the fence in cm
const float margin_cm = _fence.get_margin() * 100.0f;
if (margin_cm > fence_radius) {
return;
}
// get vehicle distance from home
const float dist_from_home = position_xy.length();
if (dist_from_home > fence_radius) {
// outside of circular fence, no velocity adjustments
return;
}
const float distance_to_boundary = fence_radius - dist_from_home;
// for backing away
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
// back away if vehicle has breached margin
if (is_negative(distance_to_boundary - margin_cm)) {
calc_backup_velocity_2D(kP, accel_cmss, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, margin_cm - distance_to_boundary, position_xy, dt);
}
// desired backup velocity is sum of maximum velocity component in each quadrant
backup_vel = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
// vehicle is inside the circular fence
switch (_behavior) {
case BEHAVIOR_SLIDE: {
// implement sliding behaviour
const Vector2f stopping_point = position_xy + desired_vel_cms*(get_stopping_distance(kP, accel_cmss, desired_speed)/desired_speed);
const float stopping_point_dist_from_home = stopping_point.length();
if (stopping_point_dist_from_home <= fence_radius - margin_cm) {
// stopping before before fence so no need to adjust
return;
}
// unsafe desired velocity - will not be able to stop before reaching margin from fence
// Project stopping point radially onto fence boundary
// Adjusted velocity will point towards this projected point at a safe speed
const Vector2f target_offset = stopping_point * ((fence_radius - margin_cm) / stopping_point_dist_from_home);
const Vector2f target_direction = target_offset - position_xy;
const float distance_to_target = target_direction.length();
if (is_positive(distance_to_target)) {
const float max_speed = get_max_speed(kP, accel_cmss, distance_to_target, dt);
desired_vel_cms = target_direction * (MIN(desired_speed,max_speed) / distance_to_target);
}
break;
}
case (BEHAVIOR_STOP): {
// implement stopping behaviour
// calculate stopping point plus a margin so we look forward far enough to intersect with circular fence
const Vector2f stopping_point_plus_margin = position_xy + desired_vel_cms*((2.0f + margin_cm + get_stopping_distance(kP, accel_cmss, desired_speed))/desired_speed);
const float stopping_point_plus_margin_dist_from_home = stopping_point_plus_margin.length();
if (dist_from_home >= fence_radius - margin_cm) {
// vehicle has already breached margin around fence
// if stopping point is even further from home (i.e. in wrong direction) then adjust speed to zero
// otherwise user is backing away from fence so do not apply limits
if (stopping_point_plus_margin_dist_from_home >= dist_from_home) {
desired_vel_cms.zero();
}
} else {
// shorten vector without adjusting its direction
Vector2f intersection;
if (Vector2f::circle_segment_intersection(position_xy, stopping_point_plus_margin, Vector2f(0.0f,0.0f), fence_radius - margin_cm, intersection)) {
const float distance_to_target = (intersection - position_xy).length();
const float max_speed = get_max_speed(kP, accel_cmss, distance_to_target, dt);
if (max_speed < desired_speed) {
desired_vel_cms *= MAX(max_speed, 0.0f) / desired_speed;
}
}
}
break;
}
}
}
/*
* Adjusts the desired velocity for the exclusion polygons
*/
void AC_Avoid::adjust_velocity_inclusion_and_exclusion_polygons(float kP, float accel_cmss, Vector2f &desired_vel_cms, Vector2f &backup_vel, float dt)
{
const AC_Fence *fence = AP::fence();
if (fence == nullptr) {
return;
}
// exit if polygon fences are not enabled
if ((fence->get_enabled_fences() & AC_FENCE_TYPE_POLYGON) == 0) {
return;
}
// for backing away
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
// iterate through inclusion polygons
const uint8_t num_inclusion_polygons = fence->polyfence().get_inclusion_polygon_count();
for (uint8_t i = 0; i < num_inclusion_polygons; i++) {
uint16_t num_points;
const Vector2f* boundary = fence->polyfence().get_inclusion_polygon(i, num_points);
Vector2f backup_vel_inc;
// adjust velocity
adjust_velocity_polygon(kP, accel_cmss, desired_vel_cms, backup_vel_inc, boundary, num_points, fence->get_margin(), dt, true);
find_max_quadrant_velocity(backup_vel_inc, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
}
// iterate through exclusion polygons
const uint8_t num_exclusion_polygons = fence->polyfence().get_exclusion_polygon_count();
for (uint8_t i = 0; i < num_exclusion_polygons; i++) {
uint16_t num_points;
const Vector2f* boundary = fence->polyfence().get_exclusion_polygon(i, num_points);
Vector2f backup_vel_exc;
// adjust velocity
adjust_velocity_polygon(kP, accel_cmss, desired_vel_cms, backup_vel_exc, boundary, num_points, fence->get_margin(), dt, false);
find_max_quadrant_velocity(backup_vel_exc, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel);
}
// desired backup velocity is sum of maximum velocity component in each quadrant
backup_vel = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
}
/*
* Adjusts the desired velocity for the inclusion circles
*/
void AC_Avoid::adjust_velocity_inclusion_circles(float kP, float accel_cmss, Vector2f &desired_vel_cms, Vector2f &backup_vel, float dt)
{
const AC_Fence *fence = AP::fence();
if (fence == nullptr) {
return;
}
// return immediately if no inclusion circles
const uint8_t num_circles = fence->polyfence().get_inclusion_circle_count();
if (num_circles == 0) {
return;
}
// exit if polygon fences are not enabled
if ((fence->get_enabled_fences() & AC_FENCE_TYPE_POLYGON) == 0) {
return;
}
// get vehicle position
Vector2f position_NE;
if (!AP::ahrs().get_relative_position_NE_origin(position_NE)) {
// do not limit velocity if we don't have a position estimate
return;
}
position_NE = position_NE * 100.0f; // m to cm
// get the margin to the fence in cm
const float margin_cm = fence->get_margin() * 100.0f;
// get desired speed
const float desired_speed = desired_vel_cms.length();
// get stopping distance as an offset from the vehicle
Vector2f stopping_offset;
if (!is_zero(desired_speed)) {
switch (_behavior) {
case BEHAVIOR_SLIDE:
stopping_offset = desired_vel_cms*(get_stopping_distance(kP, accel_cmss, desired_speed)/desired_speed);
break;
case BEHAVIOR_STOP:
// calculate stopping point plus a margin so we look forward far enough to intersect with circular fence
stopping_offset = desired_vel_cms*((2.0f + margin_cm + get_stopping_distance(kP, accel_cmss, desired_speed))/desired_speed);
break;
}
}
// for backing away
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
// iterate through inclusion circles
for (uint8_t i = 0; i < num_circles; i++) {
Vector2f center_pos_cm;
float radius;
if (fence->polyfence().get_inclusion_circle(i, center_pos_cm, radius)) {
// get position relative to circle's center
const Vector2f position_NE_rel = (position_NE - center_pos_cm);
// if we are outside this circle do not limit velocity for this circle
const float dist_sq_cm = position_NE_rel.length_squared();
const float radius_cm = (radius * 100.0f);
if (dist_sq_cm > sq(radius_cm)) {
continue;
}
const float radius_with_margin = radius_cm - margin_cm;
if (is_negative(radius_with_margin)) {
return;
}
const float margin_breach = radius_with_margin - safe_sqrt(dist_sq_cm);
// back away if vehicle has breached margin
if (is_negative(margin_breach)) {
calc_backup_velocity_2D(kP, accel_cmss, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, margin_breach, position_NE_rel, dt);
}
if (is_zero(desired_speed)) {
// no avoidance necessary when desired speed is zero
continue;
}
switch (_behavior) {
case BEHAVIOR_SLIDE: {
// implement sliding behaviour
const Vector2f stopping_point = position_NE_rel + stopping_offset;
const float stopping_point_dist = stopping_point.length();
if (is_zero(stopping_point_dist) || (stopping_point_dist <= (radius_cm - margin_cm))) {
// stopping before before fence so no need to adjust for this circle
continue;
}
// unsafe desired velocity - will not be able to stop before reaching margin from fence
// project stopping point radially onto fence boundary
// adjusted velocity will point towards this projected point at a safe speed
const Vector2f target_offset = stopping_point * ((radius_cm - margin_cm) / stopping_point_dist);
const Vector2f target_direction = target_offset - position_NE_rel;
const float distance_to_target = target_direction.length();
if (is_positive(distance_to_target)) {
const float max_speed = get_max_speed(kP, accel_cmss, distance_to_target, dt);
desired_vel_cms = target_direction * (MIN(desired_speed,max_speed) / distance_to_target);
}
}
break;
case BEHAVIOR_STOP: {
// implement stopping behaviour
const Vector2f stopping_point_plus_margin = position_NE_rel + stopping_offset;
const float dist_cm = safe_sqrt(dist_sq_cm);
if (dist_cm >= radius_cm - margin_cm) {
// vehicle has already breached margin around fence
// if stopping point is even further from center (i.e. in wrong direction) then adjust speed to zero
// otherwise user is backing away from fence so do not apply limits
if (stopping_point_plus_margin.length() >= dist_cm) {
desired_vel_cms.zero();
// desired backup velocity is sum of maximum velocity component in each quadrant
backup_vel = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
return;
}
} else {
// shorten vector without adjusting its direction
Vector2f intersection;
if (Vector2f::circle_segment_intersection(position_NE_rel, stopping_point_plus_margin, Vector2f(0.0f,0.0f), radius_cm - margin_cm, intersection)) {
const float distance_to_target = (intersection - position_NE_rel).length();
const float max_speed = get_max_speed(kP, accel_cmss, distance_to_target, dt);
if (max_speed < desired_speed) {
desired_vel_cms *= MAX(max_speed, 0.0f) / desired_speed;
}
}
}
}
break;
}
}
}
// desired backup velocity is sum of maximum velocity component in each quadrant
backup_vel = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
}
/*
* Adjusts the desired velocity for the exclusion circles
*/
void AC_Avoid::adjust_velocity_exclusion_circles(float kP, float accel_cmss, Vector2f &desired_vel_cms, Vector2f &backup_vel, float dt)
{
const AC_Fence *fence = AP::fence();
if (fence == nullptr) {
return;
}
// return immediately if no inclusion circles
const uint8_t num_circles = fence->polyfence().get_exclusion_circle_count();
if (num_circles == 0) {
return;
}
// exit if polygon fences are not enabled
if ((fence->get_enabled_fences() & AC_FENCE_TYPE_POLYGON) == 0) {
return;
}
// get vehicle position
Vector2f position_NE;
if (!AP::ahrs().get_relative_position_NE_origin(position_NE)) {
// do not limit velocity if we don't have a position estimate
return;
}
position_NE = position_NE * 100.0f; // m to cm
// get the margin to the fence in cm
const float margin_cm = fence->get_margin() * 100.0f;
// for backing away
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
// get desired speed
const float desired_speed = desired_vel_cms.length();
// calculate stopping distance as an offset from the vehicle (only used for BEHAVIOR_STOP)
// add a margin so we look forward far enough to intersect with circular fence
Vector2f stopping_offset;
if (!is_zero(desired_speed)) {
if ((AC_Avoid::BehaviourType)_behavior.get() == BEHAVIOR_STOP) {
stopping_offset = desired_vel_cms*((2.0f + margin_cm + get_stopping_distance(kP, accel_cmss, desired_speed))/desired_speed);
}
}
// iterate through exclusion circles
for (uint8_t i = 0; i < num_circles; i++) {
Vector2f center_pos_cm;
float radius;
if (fence->polyfence().get_exclusion_circle(i, center_pos_cm, radius)) {
// get position relative to circle's center
const Vector2f position_NE_rel = (position_NE - center_pos_cm);
// if we are inside this circle do not limit velocity for this circle
const float dist_sq_cm = position_NE_rel.length_squared();
const float radius_cm = (radius * 100.0f);
if (radius_cm < margin_cm) {
return;
}
if (dist_sq_cm < sq(radius_cm)) {
continue;
}
const Vector2f vector_to_center = center_pos_cm - position_NE;
const float dist_to_boundary = vector_to_center.length() - radius_cm;
// back away if vehicle has breached margin
if (is_negative(dist_to_boundary - margin_cm)) {
calc_backup_velocity_2D(kP, accel_cmss, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, margin_cm - dist_to_boundary, vector_to_center, dt);
}
if (is_zero(desired_speed)) {
// no avoidance necessary when desired speed is zero
continue;
}
switch (_behavior) {
case BEHAVIOR_SLIDE: {
// vector from current position to circle's center
Vector2f limit_direction = vector_to_center;
if (limit_direction.is_zero()) {
// vehicle is exactly on circle center so do not limit velocity
continue;
}
// calculate distance to edge of circle
const float limit_distance_cm = limit_direction.length() - radius_cm;
if (!is_positive(limit_distance_cm)) {
// vehicle is within circle so do not limit velocity
continue;
}
// vehicle is outside the circle, adjust velocity to stay outside
limit_direction.normalize();
limit_velocity_2D(kP, accel_cmss, desired_vel_cms, limit_direction, MAX(limit_distance_cm - margin_cm, 0.0f), dt);
}
break;
case BEHAVIOR_STOP: {
// implement stopping behaviour
const Vector2f stopping_point_plus_margin = position_NE_rel + stopping_offset;
const float dist_cm = safe_sqrt(dist_sq_cm);
if (dist_cm < radius_cm + margin_cm) {
// vehicle has already breached margin around fence
// if stopping point is closer to center (i.e. in wrong direction) then adjust speed to zero
// otherwise user is backing away from fence so do not apply limits
if (stopping_point_plus_margin.length() <= dist_cm) {
desired_vel_cms.zero();
backup_vel = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
return;
}
} else {
// shorten vector without adjusting its direction
Vector2f intersection;
if (Vector2f::circle_segment_intersection(position_NE_rel, stopping_point_plus_margin, Vector2f(0.0f,0.0f), radius_cm + margin_cm, intersection)) {
const float distance_to_target = (intersection - position_NE_rel).length();
const float max_speed = get_max_speed(kP, accel_cmss, distance_to_target, dt);
if (max_speed < desired_speed) {
desired_vel_cms *= MAX(max_speed, 0.0f) / desired_speed;
}
}
}
}
break;
}
}
}
// desired backup velocity is sum of maximum velocity component in each quadrant
backup_vel = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
}
/*
* Adjusts the desired velocity for the beacon fence.
*/
void AC_Avoid::adjust_velocity_beacon_fence(float kP, float accel_cmss, Vector2f &desired_vel_cms, Vector2f &backup_vel, float dt)
{
AP_Beacon *_beacon = AP::beacon();
// exit if the beacon is not present
if (_beacon == nullptr) {
return;
}
// get boundary from beacons
uint16_t num_points = 0;
const Vector2f* boundary = _beacon->get_boundary_points(num_points);
if ((boundary == nullptr) || (num_points == 0)) {
return;
}
// adjust velocity using beacon
float margin = 0;
if (AP::fence()) {
margin = AP::fence()->get_margin();
}
adjust_velocity_polygon(kP, accel_cmss, desired_vel_cms, backup_vel, boundary, num_points, margin, dt, true);
}
/*
* Adjusts the desired velocity based on output from the proximity sensor
*/
void AC_Avoid::adjust_velocity_proximity(float kP, float accel_cmss, Vector3f &desired_vel_cms, Vector3f &backup_vel, float kP_z, float accel_cmss_z, float dt)
{
#if HAL_PROXIMITY_ENABLED
// exit immediately if proximity sensor is not present
AP_Proximity *proximity = AP::proximity();
if (!proximity) {
return;
}
AP_Proximity &_proximity = *proximity;
// check for status of the sensor
if (_proximity.get_status() != AP_Proximity::Status::Good) {
return;
}
// get total number of obstacles
const uint8_t obstacle_num = _proximity.get_obstacle_count();
if (obstacle_num == 0) {
// no obstacles
return;
}
const AP_AHRS &_ahrs = AP::ahrs();
// for backing away
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
float max_back_vel_z = 0.0f;
float min_back_vel_z = 0.0f;
// rotate velocity vector from earth frame to body-frame since obstacles are in body-frame
const Vector2f desired_vel_body_cms = _ahrs.earth_to_body2D(Vector2f{desired_vel_cms.x, desired_vel_cms.y});
// safe_vel will be adjusted to stay away from Proximity Obstacles
Vector3f safe_vel = Vector3f{desired_vel_body_cms.x, desired_vel_body_cms.y, desired_vel_cms.z};
const Vector3f safe_vel_orig = safe_vel;
// calc margin in cm
const float margin_cm = MAX(_margin * 100.0f, 0.0f);
Vector3f stopping_point;
if (!desired_vel_cms.is_zero()) {
// only used for "stop mode". Pre-calculating the stopping point here makes sure we do not need to repeat the calculations under iterations.
const float speed = safe_vel.length();
stopping_point = safe_vel * ((2.0f + get_stopping_distance(kP, accel_cmss, speed))/speed);
}
for (uint8_t i = 0; i AC_AVOID_MIN_BACKUP_BREACH_DIST) {
// this vector will help us decide how much we have to back away horizontally and vertically
const Vector3f margin_vector = vector_to_obstacle.normalized() * breach_dist;
const float xy_back_dist = norm(margin_vector.x, margin_vector.y);
const float z_back_dist = margin_vector.z;
calc_backup_velocity_3D(kP, accel_cmss, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, xy_back_dist, vector_to_obstacle, kP_z, accel_cmss_z, z_back_dist, min_back_vel_z, max_back_vel_z, dt);
}
}
if (desired_vel_cms.is_zero()) {
// cannot limit velocity if there is nothing to limit
// backing up (if needed) has already been done
continue;
}
switch (_behavior) {
case BEHAVIOR_SLIDE: {
Vector3f limit_direction{vector_to_obstacle};
// distance to closest point
const float limit_distance_cm = limit_direction.length();
if (is_zero(limit_distance_cm)) {
// We are exactly on the edge, this should ideally never be possible
// i.e. do not adjust velocity.
continue;
}
// Adjust velocity to not violate margin.
limit_velocity_3D(kP, accel_cmss, safe_vel, limit_direction, margin_cm, kP_z, accel_cmss_z, dt);
break;
}
case BEHAVIOR_STOP: {
// vector from current position to obstacle
Vector3f limit_direction;
// find intersection with line segment
const float limit_distance_cm = _proximity.distance_to_obstacle(i, Vector3f{}, stopping_point, limit_direction);
if (is_zero(limit_distance_cm)) {
// We are exactly on the edge, this should ideally never be possible
// i.e. do not adjust velocity.
return;
}
if (limit_distance_cm <= margin_cm) {
// we are within the margin so stop vehicle
safe_vel.zero();
} else {
// vehicle inside the given edge, adjust velocity to not violate this edge
limit_velocity_3D(kP, accel_cmss, safe_vel, limit_direction, margin_cm, kP_z, accel_cmss_z, dt);
}
break;
}
}
}
// desired backup velocity is sum of maximum velocity component in each quadrant
const Vector2f desired_back_vel_cms_xy = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
const float desired_back_vel_cms_z = max_back_vel_z + min_back_vel_z;
if (safe_vel == safe_vel_orig && desired_back_vel_cms_xy.is_zero() && is_zero(desired_back_vel_cms_z)) {
// proximity avoidance did nothing, no point in doing the calculations below. Return early
backup_vel.zero();
return;
}
// set modified desired velocity vector and back away velocity vector
// vectors were in body-frame, rotate resulting vector back to earth-frame
const Vector2f safe_vel_2d = _ahrs.body_to_earth2D(Vector2f{safe_vel.x, safe_vel.y});
desired_vel_cms = Vector3f{safe_vel_2d.x, safe_vel_2d.y, safe_vel.z};
const Vector2f backup_vel_xy = _ahrs.body_to_earth2D(desired_back_vel_cms_xy);
backup_vel = Vector3f{backup_vel_xy.x, backup_vel_xy.y, desired_back_vel_cms_z};
#endif // HAL_PROXIMITY_ENABLED
}
/*
* Adjusts the desired velocity for the polygon fence.
*/
void AC_Avoid::adjust_velocity_polygon(float kP, float accel_cmss, Vector2f &desired_vel_cms, Vector2f &backup_vel, const Vector2f* boundary, uint16_t num_points, float margin, float dt, bool stay_inside)
{
// exit if there are no points
if (boundary == nullptr || num_points == 0) {
return;
}
const AP_AHRS &_ahrs = AP::ahrs();
// do not adjust velocity if vehicle is outside the polygon fence
Vector2f position_xy;
if (!_ahrs.get_relative_position_NE_origin(position_xy)) {
// boundary is in earth frame but we have no idea
// where we are
return;
}
position_xy = position_xy * 100.0f; // m to cm
// return if we have already breached polygon
const bool inside_polygon = !Polygon_outside(position_xy, boundary, num_points);
if (inside_polygon != stay_inside) {
return;
}
// Safe_vel will be adjusted to remain within fence.
// We need a separate vector in case adjustment fails,
// e.g. if we are exactly on the boundary.
Vector2f safe_vel(desired_vel_cms);
Vector2f desired_back_vel_cms;
// calc margin in cm
const float margin_cm = MAX(margin * 100.0f, 0.0f);
// for stopping
const float speed = safe_vel.length();
Vector2f stopping_point_plus_margin;
if (!desired_vel_cms.is_zero()) {
stopping_point_plus_margin = position_xy + safe_vel*((2.0f + margin_cm + get_stopping_distance(kP, accel_cmss, speed))/speed);
}
// for backing away
Vector2f quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel;
for (uint16_t i=0; i= num_points) {
j = 0;
}
// end points of current edge
Vector2f start = boundary[j];
Vector2f end = boundary[i];
Vector2f vector_to_boundary = Vector2f::closest_point(position_xy, start, end) - position_xy;
// back away if vehicle has breached margin
if (is_negative(vector_to_boundary.length() - margin_cm)) {
calc_backup_velocity_2D(kP, accel_cmss, quad_1_back_vel, quad_2_back_vel, quad_3_back_vel, quad_4_back_vel, margin_cm-vector_to_boundary.length(), vector_to_boundary, dt);
}
// exit immediately if no desired velocity
if (desired_vel_cms.is_zero()) {
continue;
}
switch (_behavior) {
case (BEHAVIOR_SLIDE): {
// vector from current position to closest point on current edge
Vector2f limit_direction = vector_to_boundary;
// distance to closest point
const float limit_distance_cm = limit_direction.length();
if (is_zero(limit_distance_cm)) {
// We are exactly on the edge - treat this as a fence breach.
// i.e. do not adjust velocity.
return;
}
// We are strictly inside the given edge.
// Adjust velocity to not violate this edge.
limit_direction /= limit_distance_cm;
limit_velocity_2D(kP, accel_cmss, safe_vel, limit_direction, MAX(limit_distance_cm - margin_cm, 0.0f), dt);
break;
}
case (BEHAVIOR_STOP): {
// find intersection with line segment
Vector2f intersection;
if (Vector2f::segment_intersection(position_xy, stopping_point_plus_margin, start, end, intersection)) {
// vector from current position to point on current edge
Vector2f limit_direction = intersection - position_xy;
const float limit_distance_cm = limit_direction.length();
if (is_zero(limit_distance_cm)) {
// We are exactly on the edge - treat this as a fence breach.
// i.e. do not adjust velocity.
return;
}
if (limit_distance_cm <= margin_cm) {
// we are within the margin so stop vehicle
safe_vel.zero();
} else {
// vehicle inside the given edge, adjust velocity to not violate this edge
limit_direction /= limit_distance_cm;
limit_velocity_2D(kP, accel_cmss, safe_vel, limit_direction, MAX(limit_distance_cm - margin_cm, 0.0f), dt);
}
}
break;
}
}
}
// desired backup velocity is sum of maximum velocity component in each quadrant
desired_back_vel_cms = quad_1_back_vel + quad_2_back_vel + quad_3_back_vel + quad_4_back_vel;
// set modified desired velocity vector or back away velocity vector
desired_vel_cms = safe_vel;
backup_vel = desired_back_vel_cms;
}
/*
* Computes distance required to stop, given current speed.
*
* Implementation copied from AC_PosControl.
*/
float AC_Avoid::get_stopping_distance(float kP, float accel_cmss, float speed_cms) const
{
// avoid divide by zero by using current position if the velocity is below 10cm/s, kP is very low or acceleration is zero
if (accel_cmss <= 0.0f || is_zero(speed_cms)) {
return 0.0f;
}
// handle linear deceleration
if (kP <= 0.0f) {
return 0.5f * sq(speed_cms) / accel_cmss;
}
// calculate distance within which we can stop
// accel_cmss/kP is the point at which velocity switches from linear to sqrt
if (speed_cms < accel_cmss/kP) {
return speed_cms/kP;
} else {
// accel_cmss/(2.0f*kP*kP) is the distance at which we switch from linear to sqrt response
return accel_cmss/(2.0f*kP*kP) + (speed_cms*speed_cms)/(2.0f*accel_cmss);
}
}
// convert distance (in meters) to a lean percentage (in 0~1 range) for use in manual flight modes
float AC_Avoid::distance_to_lean_pct(float dist_m)
{
// ignore objects beyond DIST_MAX
if (dist_m < 0.0f || dist_m >= _dist_max || _dist_max <= 0.0f) {
return 0.0f;
}
// inverted but linear response
return 1.0f - (dist_m / _dist_max);
}
// returns the maximum positive and negative roll and pitch percentages (in -1 ~ +1 range) based on the proximity sensor
void AC_Avoid::get_proximity_roll_pitch_pct(float &roll_positive, float &roll_negative, float &pitch_positive, float &pitch_negative)
{
#if HAL_PROXIMITY_ENABLED
AP_Proximity *proximity = AP::proximity();
if (proximity == nullptr) {
return;
}
AP_Proximity &_proximity = *proximity;
// exit immediately if proximity sensor is not present
if (_proximity.get_status() != AP_Proximity::Status::Good) {
return;
}
const uint8_t obj_count = _proximity.get_object_count();
// if no objects return
if (obj_count == 0) {
return;
}
// calculate maximum roll, pitch values from objects
for (uint8_t i=0; i 0.0f) {
roll_positive = MAX(roll_positive, roll_pct);
} else if (roll_pct < 0.0f) {
roll_negative = MIN(roll_negative, roll_pct);
}
if (pitch_pct > 0.0f) {
pitch_positive = MAX(pitch_positive, pitch_pct);
} else if (pitch_pct < 0.0f) {
pitch_negative = MIN(pitch_negative, pitch_pct);
}
}
}
}
#endif // HAL_PROXIMITY_ENABLED
}
// singleton instance
AC_Avoid *AC_Avoid::_singleton;
namespace AP {
AC_Avoid *ac_avoid()
{
return AC_Avoid::get_singleton();
}
}