ardupilot/libraries/AP_Beacon/AP_Beacon.cpp

/*
   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_Beacon.h"
#include "AP_Beacon_Backend.h"
#include "AP_Beacon_Pozyx.h"
#include "AP_Beacon_Marvelmind.h"
#include "AP_Beacon_SITL.h"

extern const AP_HAL::HAL &hal;

// table of user settable parameters
const AP_Param::GroupInfo AP_Beacon::var_info[] = {

    // @Param: _TYPE
    // @DisplayName: Beacon based position estimation device type
    // @Description: What type of beacon based position estimation device is connected
    // @Values: 0:None,1:Pozyx,2:Marvelmind
    // @User: Advanced
    AP_GROUPINFO("_TYPE",    0, AP_Beacon, _type, 0),

    // @Param: _LATITUDE
    // @DisplayName: Beacon origin's latitude
    // @Description: Beacon origin's latitude
    // @Units: deg
    // @Increment: 0.000001
    // @Range: -90 90
    // @User: Advanced
    AP_GROUPINFO("_LATITUDE", 1, AP_Beacon, origin_lat, 0),

    // @Param: _LONGITUDE
    // @DisplayName: Beacon origin's longitude
    // @Description: Beacon origin's longitude
    // @Units: deg
    // @Increment: 0.000001
    // @Range: -180 180
    // @User: Advanced
    AP_GROUPINFO("_LONGITUDE", 2, AP_Beacon, origin_lon, 0),

    // @Param: _ALT
    // @DisplayName: Beacon origin's altitude above sealevel in meters
    // @Description: Beacon origin's altitude above sealevel in meters
    // @Units: m
    // @Increment: 1
    // @Range: 0 10000
    // @User: Advanced
    AP_GROUPINFO("_ALT", 3, AP_Beacon, origin_alt, 0),

    // @Param: _ORIENT_YAW
    // @DisplayName: Beacon systems rotation from north in degrees
    // @Description: Beacon systems rotation from north in degrees
    // @Units: deg
    // @Increment: 1
    // @Range: -180 +180
    // @User: Advanced
    AP_GROUPINFO("_ORIENT_YAW", 4, AP_Beacon, orient_yaw, 0),

    AP_GROUPEND
};

AP_Beacon::AP_Beacon(AP_SerialManager &_serial_manager) :
    serial_manager(_serial_manager)
{
    AP_Param::setup_object_defaults(this, var_info);
}

// initialise the AP_Beacon class
void AP_Beacon::init(void)
{
    if (_driver != nullptr) {
        // init called a 2nd time?
        return;
    }

    // create backend
    if (_type == AP_BeaconType_Pozyx) {
        _driver = new AP_Beacon_Pozyx(*this, serial_manager);
    } else if (_type == AP_BeaconType_Marvelmind) {
        _driver = new AP_Beacon_Marvelmind(*this, serial_manager);
    }
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
    if (_type == AP_BeaconType_SITL) {
        _driver = new AP_Beacon_SITL(*this);
    }
#endif
}

// return true if beacon feature is enabled
bool AP_Beacon::enabled(void)
{
    return (_type != AP_BeaconType_None);
}

// return true if sensor is basically healthy (we are receiving data)
bool AP_Beacon::healthy(void)
{
    if (!device_ready()) {
        return false;
    }
    return _driver->healthy();
}

// update state. This should be called often from the main loop
void AP_Beacon::update(void)
{
    if (!device_ready()) {
        return;
    }
    _driver->update();

    // update boundary for fence
    update_boundary_points();
}

// return origin of position estimate system
bool AP_Beacon::get_origin(Location &origin_loc) const
{
    if (!device_ready()) {
        return false;
    }

    // check for un-initialised origin
    if (is_zero(origin_lat) && is_zero(origin_lon) && is_zero(origin_alt)) {
        return false;
    }

    // return origin
    origin_loc.lat = origin_lat * 1.0e7;
    origin_loc.lng = origin_lon * 1.0e7;
    origin_loc.alt = origin_alt * 100;
    origin_loc.options = 0; // all flags to zero meaning alt-above-sea-level

    return true;
}

// return position in NED from position estimate system's origin in meters
bool AP_Beacon::get_vehicle_position_ned(Vector3f &position, float& accuracy_estimate) const
{
    if (!device_ready()) {
        return false;
    }

    // check for timeout
    if (AP_HAL::millis() - veh_pos_update_ms > AP_BEACON_TIMEOUT_MS) {
        return false;
    }

    // return position
    position = veh_pos_ned;
    accuracy_estimate = veh_pos_accuracy;
    return true;
}

// return the number of beacons
uint8_t AP_Beacon::count() const
{
    if (!device_ready()) {
        return 0;
    }
    return num_beacons;
}

// return all beacon data
bool AP_Beacon::get_beacon_data(uint8_t beacon_instance, struct BeaconState& state) const
{
    if (!device_ready() || beacon_instance >= num_beacons) {
        return false;
    }
    state = beacon_state[beacon_instance];
    return true;
}

// return individual beacon's id
uint8_t AP_Beacon::beacon_id(uint8_t beacon_instance) const
{
    if (beacon_instance >= num_beacons) {
        return 0;
    }
    return beacon_state[beacon_instance].id;
}

// return beacon health
bool AP_Beacon::beacon_healthy(uint8_t beacon_instance) const
{
    if (beacon_instance >= num_beacons) {
        return false;
    }
    return beacon_state[beacon_instance].healthy;
}

// return distance to beacon in meters
float AP_Beacon::beacon_distance(uint8_t beacon_instance) const
{
    if (!beacon_state[beacon_instance].healthy || beacon_instance >= num_beacons) {
        return 0.0f;
    }
    return beacon_state[beacon_instance].distance;
}

// return beacon position in meters
Vector3f AP_Beacon::beacon_position(uint8_t beacon_instance) const
{
    if (!device_ready() || beacon_instance >= num_beacons) {
        Vector3f temp = {};
        return temp;
    }
    return beacon_state[beacon_instance].position;
}

// return last update time from beacon in milliseconds
uint32_t AP_Beacon::beacon_last_update_ms(uint8_t beacon_instance) const
{
    if (_type == AP_BeaconType_None || beacon_instance >= num_beacons) {
        return 0;
    }
    return beacon_state[beacon_instance].distance_update_ms;
}

// create fence boundary points
void AP_Beacon::update_boundary_points()
{
    // we need three beacons at least to create boundary fence.
    // update boundary fence if number of beacons changes
    if (!device_ready() || num_beacons < AP_BEACON_MINIMUM_FENCE_BEACONS || boundary_num_beacons == num_beacons) {
        return;
    }

    // record number of beacons so we do not repeat calculations
    boundary_num_beacons = num_beacons;

    // accumulate beacon points
    Vector2f beacon_points[AP_BEACON_MAX_BEACONS];
    for (uint8_t index = 0; index < num_beacons; index++) {
        const Vector3f& point_3d = beacon_position(index);
        beacon_points[index].x = point_3d.x;
        beacon_points[index].y = point_3d.y;
    }

    // create polygon around boundary points using the following algorithm
    //     set the "current point" as the first boundary point
    //     loop through all the boundary points looking for the point which creates a vector (from the current point to this new point) with the lowest angle
    //     check if point is already in boundary
    //       - no: add to boundary, move current point to this new point and repeat the above
    //       - yes: we've completed the bounding box, delete any boundary points found earlier than the duplicate

    Vector2f boundary_points[AP_BEACON_MAX_BEACONS+1];  // array of boundary points
    uint8_t curr_boundary_idx = 0;                      // index into boundary_sorted index.  always points to the highest filled in element of the array
    uint8_t curr_beacon_idx = 0;                        // index into beacon_point array.  point indexed is same point as curr_boundary_idx's

    // initialise first point of boundary_sorted with first beacon's position (this point may be removed later if it is found to not be on the outer boundary)
    boundary_points[curr_boundary_idx] = beacon_points[curr_beacon_idx];

    bool boundary_success = false;  // true once the boundary has been successfully found
    bool boundary_failure = false;  // true if we fail to build the boundary
    float start_angle = 0.0f;		// starting angle used when searching for next boundary point, on each iteration this climbs but never climbs past PI * 2
    while (!boundary_success && !boundary_failure) {
        // look for next outer point
        uint8_t next_idx;
        float next_angle;
        if (get_next_boundary_point(beacon_points, num_beacons, curr_beacon_idx, start_angle, next_idx, next_angle)) {
            // add boundary point to boundary_sorted array
            curr_boundary_idx++;
            boundary_points[curr_boundary_idx] = beacon_points[next_idx];
            curr_beacon_idx = next_idx;
            start_angle = next_angle;

            // check if we have a complete boundary by looking for duplicate points within the boundary_sorted
            uint8_t dup_idx = 0;
            bool dup_found = false;
            while (dup_idx < curr_boundary_idx && !dup_found) {
                dup_found = (boundary_points[dup_idx] == boundary_points[curr_boundary_idx]);
                if (!dup_found) {
                    dup_idx++;
                }
            }
            // if duplicate is found, remove all boundary points before the duplicate because they are inner points
            if (dup_found) {
                uint8_t num_pts = curr_boundary_idx - dup_idx + 1;
                if (num_pts > AP_BEACON_MINIMUM_FENCE_BEACONS) {
                    // success, copy boundary points to boundary array and convert meters to cm
                    for (uint8_t j = 0; j < num_pts; j++) {
                        boundary[j] = boundary_points[j+dup_idx] * 100.0f;
                    }
                    boundary_num_points = num_pts;
                    boundary_success = true;
                } else {
                    // boundary has too few points
                    boundary_failure = true;
                }
            }
        } else {
            // failed to create boundary - give up!
            boundary_failure = true;
        }
    }

    // clear boundary on failure
    if (boundary_failure) {
        boundary_num_points = 0;
    }
}

// find next boundary point from an array of boundary points given the current index into that array
// returns true if a next point can be found
//   current_index should be an index into the boundary_pts array
//   start_angle is an angle (in radians), the search will sweep clockwise from this angle
//   the index of the next point is returned in the next_index argument
//   the angle to the next point is returned in the next_angle argument
bool AP_Beacon::get_next_boundary_point(const Vector2f* boundary_pts, uint8_t num_points, uint8_t current_index, float start_angle, uint8_t& next_index, float& next_angle)
{
    // sanity check
    if (boundary_pts == nullptr || current_index >= num_points) {
        return false;
    }

    // get current point
    Vector2f curr_point = boundary_pts[current_index];

    // search through all points for next boundary point in a clockwise direction
    float lowest_angle = M_PI_2;
    float lowest_angle_relative = M_PI_2;
    bool lowest_found = false;
    uint8_t lowest_index = 0;
    for (uint8_t i=0; i < num_points; i++) {
        if (i != current_index) {
            Vector2f vec = boundary_pts[i] - curr_point;
            if (!vec.is_zero()) {
                float angle = wrap_2PI(atan2f(vec.y, vec.x));
                float angle_relative = wrap_2PI(angle - start_angle);
                if ((angle_relative < lowest_angle_relative) || !lowest_found) {
                    lowest_angle = angle;
                    lowest_angle_relative = angle_relative;
                    lowest_index = i;
                    lowest_found = true;
                }
            }
        }
    }

    // return results
    if (lowest_found) {
        next_index = lowest_index;
        next_angle = lowest_angle;
    }
    return lowest_found;
}

// return fence boundary array
const Vector2f* AP_Beacon::get_boundary_points(uint16_t& num_points) const
{
    if (!device_ready()) {
        num_points = 0;
        return nullptr;
    }

    num_points = boundary_num_points;
    return boundary;
}

// check if the device is ready
bool AP_Beacon::device_ready(void) const
{
    return ((_driver != nullptr) && (_type != AP_BeaconType_None));
}