ardupilot/libraries/AP_Proximity/AP_Proximity_Backend.cpp

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/*
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 <http://www.gnu.org/licenses/>.
*/
#include <AP_Common/AP_Common.h>
#include <AP_Common/Location.h>
#include <AP_AHRS/AP_AHRS.h>
#include <AC_Avoidance/AP_OADatabase.h>
#include <AP_HAL/AP_HAL.h>
#include "AP_Proximity.h"
#include "AP_Proximity_Backend.h"
/*
base class constructor.
This incorporates initialisation as well.
*/
AP_Proximity_Backend::AP_Proximity_Backend(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state) :
frontend(_frontend),
state(_state)
{
// initialise sector edge vector used for building the boundary fence
init_boundary();
}
// get distance in meters in a particular direction in degrees (0 is forward, angles increase in the clockwise direction)
bool AP_Proximity_Backend::get_horizontal_distance(float angle_deg, float &distance) const
{
uint8_t sector;
if (convert_angle_to_sector(angle_deg, sector)) {
if (_distance_valid[sector]) {
distance = _distance[sector];
return true;
}
}
return false;
}
// get distance and angle to closest object (used for pre-arm check)
// returns true on success, false if no valid readings
bool AP_Proximity_Backend::get_closest_object(float& angle_deg, float &distance) const
{
bool sector_found = false;
uint8_t sector = 0;
// check all sectors for shorter distance
for (uint8_t i=0; i<_num_sectors; i++) {
if (_distance_valid[i]) {
if (!sector_found || (_distance[i] < _distance[sector])) {
sector = i;
sector_found = true;
}
}
}
if (sector_found) {
angle_deg = _angle[sector];
distance = _distance[sector];
}
return sector_found;
}
// get number of objects, used for non-GPS avoidance
uint8_t AP_Proximity_Backend::get_object_count() const
{
return _num_sectors;
}
// get an object's angle and distance, used for non-GPS avoidance
// returns false if no angle or distance could be returned for some reason
bool AP_Proximity_Backend::get_object_angle_and_distance(uint8_t object_number, float& angle_deg, float &distance) const
{
if (object_number < _num_sectors && _distance_valid[object_number]) {
angle_deg = _angle[object_number];
distance = _distance[object_number];
return true;
}
return false;
}
// get distances in PROXIMITY_MAX_DIRECTION directions. used for sending distances to ground station
bool AP_Proximity_Backend::get_horizontal_distances(AP_Proximity::Proximity_Distance_Array &prx_dist_array) const
{
// exit immediately if we have no good ranges
bool valid_distances = false;
for (uint8_t i=0; i<_num_sectors; i++) {
if (_distance_valid[i]) {
valid_distances = true;
break;
}
}
if (!valid_distances) {
return false;
}
// initialise orientations and directions
// see MAV_SENSOR_ORIENTATION for orientations (0 = forward, 1 = 45 degree clockwise from north, etc)
// distances initialised to maximum distances
bool dist_set[PROXIMITY_MAX_DIRECTION]{};
for (uint8_t i=0; i<PROXIMITY_MAX_DIRECTION; i++) {
prx_dist_array.orientation[i] = i;
prx_dist_array.distance[i] = distance_max();
}
// cycle through all sectors filling in distances
for (uint8_t i=0; i<_num_sectors; i++) {
if (_distance_valid[i]) {
// convert angle to orientation
int16_t orientation = static_cast<int16_t>(_angle[i] * (PROXIMITY_MAX_DIRECTION / 360.0f));
if ((orientation >= 0) && (orientation < PROXIMITY_MAX_DIRECTION) && (_distance[i] < prx_dist_array.distance[orientation])) {
prx_dist_array.distance[orientation] = _distance[i];
dist_set[orientation] = true;
}
}
}
// fill in missing orientations with average of adjacent orientations if necessary and possible
for (uint8_t i=0; i<PROXIMITY_MAX_DIRECTION; i++) {
if (!dist_set[i]) {
uint8_t orient_before = (i==0) ? (PROXIMITY_MAX_DIRECTION - 1) : (i-1);
uint8_t orient_after = (i==(PROXIMITY_MAX_DIRECTION - 1)) ? 0 : (i+1);
if (dist_set[orient_before] && dist_set[orient_after]) {
prx_dist_array.distance[i] = (prx_dist_array.distance[orient_before] + prx_dist_array.distance[orient_after]) / 2.0f;
}
}
}
return true;
}
// get boundary points around vehicle for use by avoidance
// returns nullptr and sets num_points to zero if no boundary can be returned
const Vector2f* AP_Proximity_Backend::get_boundary_points(uint16_t& num_points) const
{
// high-level status check
if (state.status != AP_Proximity::Status::Good) {
num_points = 0;
return nullptr;
}
// check at least one sector has valid data, if not, exit
bool some_valid = false;
for (uint8_t i=0; i<_num_sectors; i++) {
if (_distance_valid[i]) {
some_valid = true;
break;
}
}
if (!some_valid) {
num_points = 0;
return nullptr;
}
// return boundary points
num_points = _num_sectors;
return _boundary_point;
}
// initialise the boundary and sector_edge_vector array used for object avoidance
// should be called if the sector_middle_deg or _setor_width_deg arrays are changed
void AP_Proximity_Backend::init_boundary()
{
for (uint8_t sector=0; sector < _num_sectors; sector++) {
float angle_rad = radians((float)_sector_middle_deg[sector]+(float)_sector_width_deg[sector]/2.0f);
_sector_edge_vector[sector].x = cosf(angle_rad) * 100.0f;
_sector_edge_vector[sector].y = sinf(angle_rad) * 100.0f;
_boundary_point[sector] = _sector_edge_vector[sector] * PROXIMITY_BOUNDARY_DIST_DEFAULT;
}
}
// update boundary points used for object avoidance based on a single sector's distance changing
// the boundary points lie on the line between sectors meaning two boundary points may be updated based on a single sector's distance changing
// the boundary point is set to the shortest distance found in the two adjacent sectors, this is a conservative boundary around the vehicle
void AP_Proximity_Backend::update_boundary_for_sector(const uint8_t sector, const bool push_to_OA_DB)
{
// sanity check
if (sector >= _num_sectors) {
return;
}
if (push_to_OA_DB) {
database_push(_angle[sector], _distance[sector]);
}
// find adjacent sector (clockwise)
uint8_t next_sector = sector + 1;
if (next_sector >= _num_sectors) {
next_sector = 0;
}
// boundary point lies on the line between the two sectors at the shorter distance found in the two sectors
float shortest_distance = PROXIMITY_BOUNDARY_DIST_DEFAULT;
if (_distance_valid[sector] && _distance_valid[next_sector]) {
shortest_distance = MIN(_distance[sector], _distance[next_sector]);
} else if (_distance_valid[sector]) {
shortest_distance = _distance[sector];
} else if (_distance_valid[next_sector]) {
shortest_distance = _distance[next_sector];
}
if (shortest_distance < PROXIMITY_BOUNDARY_DIST_MIN) {
shortest_distance = PROXIMITY_BOUNDARY_DIST_MIN;
}
_boundary_point[sector] = _sector_edge_vector[sector] * shortest_distance;
// if the next sector (clockwise) has an invalid distance, set boundary to create a cup like boundary
if (!_distance_valid[next_sector]) {
_boundary_point[next_sector] = _sector_edge_vector[next_sector] * shortest_distance;
}
// repeat for edge between sector and previous sector
uint8_t prev_sector = (sector == 0) ? _num_sectors-1 : sector-1;
shortest_distance = PROXIMITY_BOUNDARY_DIST_DEFAULT;
if (_distance_valid[prev_sector] && _distance_valid[sector]) {
shortest_distance = MIN(_distance[prev_sector], _distance[sector]);
} else if (_distance_valid[prev_sector]) {
shortest_distance = _distance[prev_sector];
} else if (_distance_valid[sector]) {
shortest_distance = _distance[sector];
}
_boundary_point[prev_sector] = _sector_edge_vector[prev_sector] * shortest_distance;
// if the sector counter-clockwise from the previous sector has an invalid distance, set boundary to create a cup like boundary
uint8_t prev_sector_ccw = (prev_sector == 0) ? _num_sectors-1 : prev_sector-1;
if (!_distance_valid[prev_sector_ccw]) {
_boundary_point[prev_sector_ccw] = _sector_edge_vector[prev_sector_ccw] * shortest_distance;
}
}
// set status and update valid count
void AP_Proximity_Backend::set_status(AP_Proximity::Status status)
{
state.status = status;
}
bool AP_Proximity_Backend::convert_angle_to_sector(float angle_degrees, uint8_t &sector) const
{
// sanity check angle
if (angle_degrees > 360.0f || angle_degrees < -180.0f) {
return false;
}
// convert to 0 ~ 360
if (angle_degrees < 0.0f) {
angle_degrees += 360.0f;
}
bool closest_found = false;
uint8_t closest_sector;
float closest_angle;
// search for which sector angle_degrees falls into
for (uint8_t i = 0; i < _num_sectors; i++) {
float angle_diff = fabsf(wrap_180(_sector_middle_deg[i] - angle_degrees));
// record if closest
if (!closest_found || angle_diff < closest_angle) {
closest_found = true;
closest_sector = i;
closest_angle = angle_diff;
}
if (fabsf(angle_diff) <= _sector_width_deg[i] / 2.0f) {
sector = i;
return true;
}
}
// angle_degrees might have been within a gap between sectors
if (closest_found) {
sector = closest_sector;
return true;
}
return false;
}
// get ignore area info
uint8_t AP_Proximity_Backend::get_ignore_area_count() const
{
// count number of ignore sectors
uint8_t count = 0;
for (uint8_t i=0; i < PROXIMITY_MAX_IGNORE; i++) {
if (frontend._ignore_width_deg[i] != 0) {
count++;
}
}
return count;
}
// get next ignore angle
bool AP_Proximity_Backend::get_ignore_area(uint8_t index, uint16_t &angle_deg, uint8_t &width_deg) const
{
if (index >= PROXIMITY_MAX_IGNORE) {
return false;
}
angle_deg = frontend._ignore_angle_deg[index];
width_deg = frontend._ignore_width_deg[index];
return true;
}
// retrieve start or end angle of next ignore area (i.e. closest ignore area higher than the start_angle)
// start_or_end = 0 to get start, 1 to retrieve end
bool AP_Proximity_Backend::get_next_ignore_start_or_end(uint8_t start_or_end, int16_t start_angle, int16_t &ignore_start) const
{
bool found = false;
int16_t smallest_angle_diff = 0;
int16_t smallest_angle_start = 0;
for (uint8_t i=0; i < PROXIMITY_MAX_IGNORE; i++) {
if (frontend._ignore_width_deg[i] != 0) {
int16_t offset = start_or_end == 0 ? -frontend._ignore_width_deg[i] : +frontend._ignore_width_deg[i];
int16_t ignore_start_angle = wrap_360(frontend._ignore_angle_deg[i] + offset/2.0f);
int16_t ang_diff = wrap_360(ignore_start_angle - start_angle);
if (!found || ang_diff < smallest_angle_diff) {
smallest_angle_diff = ang_diff;
smallest_angle_start = ignore_start_angle;
found = true;
}
}
}
if (found) {
ignore_start = smallest_angle_start;
}
return found;
}
// returns true if database is ready to be pushed to and all cached data is ready
bool AP_Proximity_Backend::database_prepare_for_push(Location &current_loc, float &current_vehicle_bearing)
{
AP_OADatabase *oaDb = AP::oadatabase();
if (oaDb == nullptr || !oaDb->healthy()) {
return false;
}
if (!AP::ahrs().get_position(current_loc)) {
return false;
}
current_vehicle_bearing = AP::ahrs().yaw_sensor * 0.01f;
return true;
}
// update Object Avoidance database with Earth-frame point
void AP_Proximity_Backend::database_push(const float angle, const float distance)
{
Location current_loc;
float current_vehicle_bearing;
if (database_prepare_for_push(current_loc, current_vehicle_bearing) == true) {
database_push(angle, distance, AP_HAL::millis(), current_loc, current_vehicle_bearing);
}
}
// update Object Avoidance database with Earth-frame point
void AP_Proximity_Backend::database_push(const float angle, const float distance, const uint32_t timestamp_ms, const Location &current_loc, const float current_vehicle_bearing)
{
AP_OADatabase *oaDb = AP::oadatabase();
if (oaDb == nullptr || !oaDb->healthy()) {
return;
}
Location temp_loc = current_loc;
temp_loc.offset_bearing(wrap_180(current_vehicle_bearing + angle), distance);
oaDb->queue_push(temp_loc, timestamp_ms, distance, angle);
}