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ardupilot/libraries/AC_PrecLand/AC_PrecLand.cpp

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#include <AP_HAL/AP_HAL.h>
#include <AP_Scheduler/AP_Scheduler.h>
#include <AP_AHRS/AP_AHRS.h>
#include "AC_PrecLand.h"
#include "AC_PrecLand_Backend.h"
#include "AC_PrecLand_Companion.h"
#include "AC_PrecLand_IRLock.h"
#include "AC_PrecLand_SITL_Gazebo.h"
#include "AC_PrecLand_SITL.h"
#include <AP_Logger/AP_Logger.h>
#include <GCS_MAVLink/GCS.h>
#include <AP_Vehicle/AP_Vehicle_Type.h>
extern const AP_HAL::HAL& hal;
#if APM_BUILD_TYPE(APM_BUILD_Rover)
# define AC_PRECLAND_ORIENT_DEFAULT Rotation::ROTATION_NONE
#else
# define AC_PRECLAND_ORIENT_DEFAULT Rotation::ROTATION_PITCH_270
#endif
static const uint32_t EKF_INIT_TIME_MS = 2000; // EKF initialisation requires this many milliseconds of good sensor data
static const uint32_t EKF_INIT_SENSOR_MIN_UPDATE_MS = 500; // Sensor must update within this many ms during EKF init, else init will fail
static const uint32_t LANDING_TARGET_TIMEOUT_MS = 2000; // Sensor must update within this many ms, else prec landing will be switched off
static const uint32_t LANDING_TARGET_LOST_TIMEOUT_MS = 180000; // Target will be considered as "lost" if the last known location of the target is more than this many ms ago
static const float LANDING_TARGET_LOST_DIST_THRESH_M = 30; // If the last known location of the landing target is beyond this many meters, then we will consider it lost
const AP_Param::GroupInfo AC_PrecLand::var_info[] = {
// @Param: ENABLED
// @DisplayName: Precision Land enabled/disabled
// @Description: Precision Land enabled/disabled
// @Values: 0:Disabled, 1:Enabled
// @User: Advanced
AP_GROUPINFO_FLAGS("ENABLED", 0, AC_PrecLand, _enabled, 0, AP_PARAM_FLAG_ENABLE),
// @Param: TYPE
// @DisplayName: Precision Land Type
// @Description: Precision Land Type
// @Values: 0:None, 1:CompanionComputer, 2:IRLock, 3:SITL_Gazebo, 4:SITL
// @User: Advanced
AP_GROUPINFO("TYPE", 1, AC_PrecLand, _type, 0),
// @Param: YAW_ALIGN
// @DisplayName: Sensor yaw alignment
// @Description: Yaw angle from body x-axis to sensor x-axis.
// @Range: 0 36000
// @Increment: 10
// @User: Advanced
// @Units: cdeg
AP_GROUPINFO("YAW_ALIGN", 2, AC_PrecLand, _yaw_align, 0),
// @Param: LAND_OFS_X
// @DisplayName: Land offset forward
// @Description: Desired landing position of the camera forward of the target in vehicle body frame
// @Range: -20 20
// @Increment: 1
// @User: Advanced
// @Units: cm
AP_GROUPINFO("LAND_OFS_X", 3, AC_PrecLand, _land_ofs_cm_x, 0),
// @Param: LAND_OFS_Y
// @DisplayName: Land offset right
// @Description: desired landing position of the camera right of the target in vehicle body frame
// @Range: -20 20
// @Increment: 1
// @User: Advanced
// @Units: cm
AP_GROUPINFO("LAND_OFS_Y", 4, AC_PrecLand, _land_ofs_cm_y, 0),
// @Param: EST_TYPE
// @DisplayName: Precision Land Estimator Type
// @Description: Specifies the estimation method to be used
// @Values: 0:RawSensor, 1:KalmanFilter
// @User: Advanced
AP_GROUPINFO("EST_TYPE", 5, AC_PrecLand, _estimator_type, 1),
// @Param: ACC_P_NSE
// @DisplayName: Kalman Filter Accelerometer Noise
// @Description: Kalman Filter Accelerometer Noise, higher values weight the input from the camera more, accels less
// @Range: 0.5 5
// @User: Advanced
AP_GROUPINFO("ACC_P_NSE", 6, AC_PrecLand, _accel_noise, 2.5f),
// @Param: CAM_POS_X
// @DisplayName: Camera X position offset
// @Description: X position of the camera in body frame. Positive X is forward of the origin.
// @Units: m
// @Range: -5 5
// @Increment: 0.01
// @User: Advanced
// @Param: CAM_POS_Y
// @DisplayName: Camera Y position offset
// @Description: Y position of the camera in body frame. Positive Y is to the right of the origin.
// @Units: m
// @Range: -5 5
// @Increment: 0.01
// @User: Advanced
// @Param: CAM_POS_Z
// @DisplayName: Camera Z position offset
// @Description: Z position of the camera in body frame. Positive Z is down from the origin.
// @Units: m
// @Range: -5 5
// @Increment: 0.01
// @User: Advanced
AP_GROUPINFO("CAM_POS", 7, AC_PrecLand, _cam_offset, 0.0f),
// @Param: BUS
// @DisplayName: Sensor Bus
// @Description: Precland sensor bus for I2C sensors.
// @Values: -1:DefaultBus,0:InternalI2C,1:ExternalI2C
// @User: Advanced
AP_GROUPINFO("BUS", 8, AC_PrecLand, _bus, -1),
// @Param: LAG
// @DisplayName: Precision Landing sensor lag
// @Description: Precision Landing sensor lag, to cope with variable landing_target latency
// @Range: 0.02 0.250
// @Increment: 1
// @Units: s
// @User: Advanced
// @RebootRequired: True
AP_GROUPINFO("LAG", 9, AC_PrecLand, _lag, 0.02f), // 20ms is the old default buffer size (8 frames @ 400hz/2.5ms)
// @Param: XY_DIST_MAX
// @DisplayName: Precision Landing maximum distance to target before descending
// @Description: The vehicle will not start descending if the landing target is detected and it is further than this many meters away. Set 0 to always descend.
// @Range: 0 10
// @Units: m
// @User: Advanced
AP_GROUPINFO("XY_DIST_MAX", 10, AC_PrecLand, _xy_max_dist_desc, 2.5f),
// @Param: STRICT
// @DisplayName: PrecLand strictness
// @Description: How strictly should the vehicle land on the target if target is lost
// @Values: 0: Land Vertically (Not strict), 1: Retry Landing(Normal Strictness), 2: Do not land (just Hover) (Very Strict)
AP_GROUPINFO("STRICT", 11, AC_PrecLand, _strict, 1),
// @Param: RET_MAX
// @DisplayName: PrecLand Maximum number of retires for a failed landing
// @Description: PrecLand Maximum number of retires for a failed landing. Set to zero to disable landing retry.
// @Range: 0 10
// @Increment: 1
AP_GROUPINFO("RET_MAX", 12, AC_PrecLand, _retry_max, 4),
// @Param: TIMEOUT
// @DisplayName: PrecLand retry timeout
// @Description: Time for which vehicle continues descend even if target is lost. After this time period, vehicle will attemp a landing retry depending on PLND_STRICT parameter.
// @Range: 0 20
// @Units: s
AP_GROUPINFO("TIMEOUT", 13, AC_PrecLand, _retry_timeout_sec, 4),
// @Param: RET_BEHAVE
// @DisplayName: PrecLand retry behaviour
// @Description: Prec Land will do the action selected by this parameter if a retry to a landing is needed
// @Values: 0: Go to the last location where landing target was detected, 1: Go towards the approximate location of the detected landing target
AP_GROUPINFO("RET_BEHAVE", 14, AC_PrecLand, _retry_behave, 0),
// @Param: ALT_MIN
// @DisplayName: PrecLand minimum alt for retry
// @Description: Vehicle will continue landing vertically even if target is lost below this height. This needs a rangefinder to work. Set to zero to disable this.
// @Range: 0 5
// @Units: m
AP_GROUPINFO("ALT_MIN", 15, AC_PrecLand, _sensor_min_alt, 0.75),
// @Param: ALT_MAX
// @DisplayName: PrecLand maximum alt for retry
// @Description: Vehicle will continue landing vertically until this height if target is not found. Below this height if landing target is not found, landing retry/failsafe might be attempted. This needs a rangefinder to work. Set to zero to disable this.
// @Range: 0 50
// @Units: m
AP_GROUPINFO("ALT_MAX", 16, AC_PrecLand, _sensor_max_alt, 8),
// @Param: OPTIONS
// @DisplayName: Precision Landing Extra Options
// @Description: Precision Landing Extra Options
// @Bitmask: 0: Moving Landing Target, 1: Allow Precision Landing after manual reposition
// @User: Advanced
AP_GROUPINFO("OPTIONS", 17, AC_PrecLand, _options, 0),
// @Param: ORIENT
// @DisplayName: Camera Orientation
// @Description: Orientation of camera/sensor on body
// @Values: 0:Forward, 4:Back, 25:Down
// @User: Advanced
// @RebootRequired: True
AP_GROUPINFO_FRAME("ORIENT", 18, AC_PrecLand, _orient, AC_PRECLAND_ORIENT_DEFAULT, AP_PARAM_FRAME_ROVER),
AP_GROUPEND
};
// Default constructor.
AC_PrecLand::AC_PrecLand()
{
if (_singleton != nullptr) {
AP_HAL::panic("AC_PrecLand must be singleton");
}
_singleton = this;
// set parameters to defaults
AP_Param::setup_object_defaults(this, var_info);
}
// perform any required initialisation of landing controllers
// update_rate_hz should be the rate at which the update method will be called in hz
void AC_PrecLand::init(uint16_t update_rate_hz)
{
// exit immediately if init has already been run
if (_backend != nullptr) {
return;
}
// init as target TARGET_NEVER_SEEN, we will update this later
_current_target_state = TargetState::TARGET_NEVER_SEEN;
// default health to false
_backend = nullptr;
_backend_state.healthy = false;
// create inertial history buffer
// constrain lag parameter to be within bounds
_lag.set(constrain_float(_lag, 0.02f, 0.25f));
// calculate inertial buffer size from lag and minimum of main loop rate and update_rate_hz argument
const uint16_t inertial_buffer_size = MAX((uint16_t)roundf(_lag * MIN(update_rate_hz, AP::scheduler().get_loop_rate_hz())), 1);
// instantiate ring buffer to hold inertial history, return on failure so no backends are created
_inertial_history = new ObjectArray<inertial_data_frame_s>(inertial_buffer_size);
if (_inertial_history == nullptr) {
return;
}
// instantiate backend based on type parameter
switch ((Type)(_type.get())) {
// no type defined
case Type::NONE:
default:
return;
// companion computer
case Type::COMPANION:
_backend = new AC_PrecLand_Companion(*this, _backend_state);
break;
// IR Lock
case Type::IRLOCK:
_backend = new AC_PrecLand_IRLock(*this, _backend_state);
break;
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
case Type::SITL_GAZEBO:
_backend = new AC_PrecLand_SITL_Gazebo(*this, _backend_state);
break;
case Type::SITL:
_backend = new AC_PrecLand_SITL(*this, _backend_state);
break;
#endif
}
// init backend
if (_backend != nullptr) {
_backend->init();
}
_approach_vector_body.x = 1;
_approach_vector_body.rotate(_orient);
}
// update - give chance to driver to get updates from sensor
void AC_PrecLand::update(float rangefinder_alt_cm, bool rangefinder_alt_valid)
{
// exit immediately if not enabled
if (_backend == nullptr || _inertial_history == nullptr) {
return;
}
// append current velocity and attitude correction into history buffer
struct inertial_data_frame_s inertial_data_newest;
const auto &_ahrs = AP::ahrs();
_ahrs.getCorrectedDeltaVelocityNED(inertial_data_newest.correctedVehicleDeltaVelocityNED, inertial_data_newest.dt);
inertial_data_newest.Tbn = _ahrs.get_rotation_body_to_ned();
Vector3f curr_vel;
nav_filter_status status;
if (!_ahrs.get_velocity_NED(curr_vel) || !_ahrs.get_filter_status(status)) {
inertial_data_newest.inertialNavVelocityValid = false;
} else {
inertial_data_newest.inertialNavVelocityValid = status.flags.horiz_vel;
}
curr_vel.z = -curr_vel.z; // NED to NEU
inertial_data_newest.inertialNavVelocity = curr_vel;
inertial_data_newest.time_usec = AP_HAL::micros64();
_inertial_history->push_force(inertial_data_newest);
const float rangefinder_alt_m = rangefinder_alt_cm*0.01f; //cm to meter
// update estimator of target position
if (_backend != nullptr && _enabled) {
_backend->update();
run_estimator(rangefinder_alt_m, rangefinder_alt_valid);
}
// check the status of the landing target location
check_target_status(rangefinder_alt_m, rangefinder_alt_valid);
const uint32_t now = AP_HAL::millis();
if (now - last_log_ms > 40) { // 25Hz
last_log_ms = now;
Write_Precland();
}
}
// check the status of the target
void AC_PrecLand::check_target_status(float rangefinder_alt_m, bool rangefinder_alt_valid)
{
if (target_acquired()) {
// target in sight
_current_target_state = TargetState::TARGET_FOUND;
// early return because we already know the status
return;
}
// target not in sight
if (_current_target_state == TargetState::TARGET_FOUND ||
_current_target_state == TargetState::TARGET_RECENTLY_LOST) {
// we had target in sight, but not any more, i.e we have lost the target
_current_target_state = TargetState::TARGET_RECENTLY_LOST;
} else {
// we never had the target in sight
_current_target_state = TargetState::TARGET_NEVER_SEEN;
}
// We definitely do not have the target in sight
// check if the precision landing sensor is supposed to be in range
// this needs a valid rangefinder to work
if (!check_if_sensor_in_range(rangefinder_alt_m, rangefinder_alt_valid)) {
// Target is not in range (vehicle is either too high or too low). Vehicle will not be attempting any sort of landing retries during this period
_current_target_state = TargetState::TARGET_OUT_OF_RANGE;
return;
}
if (_current_target_state == TargetState::TARGET_RECENTLY_LOST) {
// check if it's nearby/found recently, else the status will be demoted to "TARGET_LOST"
Vector2f curr_pos;
if (AP::ahrs().get_relative_position_NE_origin(curr_pos)) {
const float dist_to_last_target_loc_xy = (curr_pos - Vector2f{_last_target_pos_rel_origin_NED.x, _last_target_pos_rel_origin_NED.y}).length();
const float dist_to_last_loc_xy = (curr_pos - Vector2f{_last_vehicle_pos_NED.x, _last_vehicle_pos_NED.y}).length();
if ((AP_HAL::millis() - _last_valid_target_ms) > LANDING_TARGET_LOST_TIMEOUT_MS) {
// the target has not been seen for a long time
// might as well consider it as "never seen"
_current_target_state = TargetState::TARGET_NEVER_SEEN;
return;
}
if ((dist_to_last_target_loc_xy > LANDING_TARGET_LOST_DIST_THRESH_M) || (dist_to_last_loc_xy > LANDING_TARGET_LOST_DIST_THRESH_M)) {
// the last known location of target is too far away
_current_target_state = TargetState::TARGET_NEVER_SEEN;
return;
}
}
}
}
// Check if the landing target is supposed to be in sight based on the height of the vehicle from the ground
// This needs a valid rangefinder to work, if the min/max parameters are non zero
bool AC_PrecLand::check_if_sensor_in_range(float rangefinder_alt_m, bool rangefinder_alt_valid) const
{
if (is_zero(_sensor_max_alt) && is_zero(_sensor_min_alt)) {
// no sensor limits have been specified, assume sensor is always in range
return true;
}
if (!rangefinder_alt_valid) {
// rangefinder isn't healthy. We might be at a very high altitude
return false;
}
if (rangefinder_alt_m > _sensor_max_alt && !is_zero(_sensor_max_alt)) {
// this prevents triggering a retry when we are too far away from the target
return false;
}
if (rangefinder_alt_m < _sensor_min_alt && !is_zero(_sensor_min_alt)) {
// this prevents triggering a retry when we are very close to the target
return false;
}
// target should be in range
return true;
}
bool AC_PrecLand::target_acquired()
{
if ((AP_HAL::millis()-_last_update_ms) > LANDING_TARGET_TIMEOUT_MS) {
if (_target_acquired) {
// just lost the landing target, inform the user. This message will only be sent once everytime target is lost
gcs().send_text(MAV_SEVERITY_CRITICAL, "PrecLand: Target Lost");
}
// not had a sensor update since a long time
// probably lost the target
_estimator_initialized = false;
_target_acquired = false;
}
return _target_acquired;
}
bool AC_PrecLand::get_target_position_cm(Vector2f& ret)
{
if (!target_acquired()) {
return false;
}
Vector2f curr_pos;
if (!AP::ahrs().get_relative_position_NE_origin(curr_pos)) {
return false;
}
ret.x = (_target_pos_rel_out_NE.x + curr_pos.x) * 100.0f; // m to cm
ret.y = (_target_pos_rel_out_NE.y + curr_pos.y) * 100.0f; // m to cm
return true;
}
void AC_PrecLand::get_target_position_measurement_cm(Vector3f& ret)
{
ret = _target_pos_rel_meas_NED*100.0f;
return;
}
bool AC_PrecLand::get_target_position_relative_cm(Vector2f& ret)
{
if (!target_acquired()) {
return false;
}
ret = _target_pos_rel_out_NE*100.0f;
return true;
}
bool AC_PrecLand::get_target_velocity_relative_cms(Vector2f& ret)
{
if (!target_acquired()) {
return false;
}
ret = _target_vel_rel_out_NE*100.0f;
return true;
}
// get the absolute velocity of the vehicle
void AC_PrecLand::get_target_velocity_cms(const Vector2f& vehicle_velocity_cms, Vector2f& target_vel_cms)
{
if (!(_options & PLND_OPTION_MOVING_TARGET)) {
// the target should not be moving
target_vel_cms.zero();
return;
}
if ((EstimatorType)_estimator_type.get() == EstimatorType::RAW_SENSOR) {
// We do not predict the velocity of the target in this case
// assume velocity to be zero
target_vel_cms.zero();
return;
}
Vector2f target_vel_rel_cms;
if (!get_target_velocity_relative_cms(target_vel_rel_cms)) {
// Don't know where the target is
// assume velocity to be zero
target_vel_cms.zero();
return;
}
// return the absolute velocity
target_vel_cms = target_vel_rel_cms + vehicle_velocity_cms;
}
// handle_msg - Process a LANDING_TARGET mavlink message
void AC_PrecLand::handle_msg(const mavlink_landing_target_t &packet, uint32_t timestamp_ms)
{
// run backend update
if (_backend != nullptr) {
_backend->handle_msg(packet, timestamp_ms);
}
}
//
// Private methods
//
void AC_PrecLand::run_estimator(float rangefinder_alt_m, bool rangefinder_alt_valid)
{
const struct inertial_data_frame_s *inertial_data_delayed = (*_inertial_history)[0];
switch ((EstimatorType)_estimator_type.get()) {
case EstimatorType::RAW_SENSOR: {
// Return if there's any invalid velocity data
for (uint8_t i=0; i<_inertial_history->available(); i++) {
const struct inertial_data_frame_s *inertial_data = (*_inertial_history)[i];
if (!inertial_data->inertialNavVelocityValid) {
_target_acquired = false;
return;
}
}
// Predict
if (target_acquired()) {
_target_pos_rel_est_NE.x -= inertial_data_delayed->inertialNavVelocity.x * inertial_data_delayed->dt;
_target_pos_rel_est_NE.y -= inertial_data_delayed->inertialNavVelocity.y * inertial_data_delayed->dt;
_target_vel_rel_est_NE.x = -inertial_data_delayed->inertialNavVelocity.x;
_target_vel_rel_est_NE.y = -inertial_data_delayed->inertialNavVelocity.y;
}
// Update if a new Line-Of-Sight measurement is available
if (construct_pos_meas_using_rangefinder(rangefinder_alt_m, rangefinder_alt_valid)) {
if (!_estimator_initialized) {
gcs().send_text(MAV_SEVERITY_INFO, "PrecLand: Target Found");
_estimator_initialized = true;
}
_target_pos_rel_est_NE.x = _target_pos_rel_meas_NED.x;
_target_pos_rel_est_NE.y = _target_pos_rel_meas_NED.y;
_target_vel_rel_est_NE.x = -inertial_data_delayed->inertialNavVelocity.x;
_target_vel_rel_est_NE.y = -inertial_data_delayed->inertialNavVelocity.y;
_last_update_ms = AP_HAL::millis();
_target_acquired = true;
}
// Output prediction
if (target_acquired()) {
run_output_prediction();
}
break;
}
case EstimatorType::KALMAN_FILTER: {
// Predict
if (target_acquired() || _estimator_initialized) {
const float& dt = inertial_data_delayed->dt;
const Vector3f& vehicleDelVel = inertial_data_delayed->correctedVehicleDeltaVelocityNED;
_ekf_x.predict(dt, -vehicleDelVel.x, _accel_noise*dt);
_ekf_y.predict(dt, -vehicleDelVel.y, _accel_noise*dt);
}
// Update if a new Line-Of-Sight measurement is available
if (construct_pos_meas_using_rangefinder(rangefinder_alt_m, rangefinder_alt_valid)) {
float xy_pos_var = sq(_target_pos_rel_meas_NED.z*(0.01f + 0.01f*AP::ahrs().get_gyro().length()) + 0.02f);
if (!_estimator_initialized) {
// Inform the user landing target has been found
gcs().send_text(MAV_SEVERITY_INFO, "PrecLand: Target Found");
// start init of EKF. We will let the filter consume the data for a while before it available for consumption
// reset filter state
if (inertial_data_delayed->inertialNavVelocityValid) {
_ekf_x.init(_target_pos_rel_meas_NED.x, xy_pos_var, -inertial_data_delayed->inertialNavVelocity.x, sq(2.0f));
_ekf_y.init(_target_pos_rel_meas_NED.y, xy_pos_var, -inertial_data_delayed->inertialNavVelocity.y, sq(2.0f));
} else {
_ekf_x.init(_target_pos_rel_meas_NED.x, xy_pos_var, 0.0f, sq(10.0f));
_ekf_y.init(_target_pos_rel_meas_NED.y, xy_pos_var, 0.0f, sq(10.0f));
}
_last_update_ms = AP_HAL::millis();
_estimator_init_ms = AP_HAL::millis();
// we have initialized the estimator but will not use the values for sometime so that EKF settles down
_estimator_initialized = true;
} else {
float NIS_x = _ekf_x.getPosNIS(_target_pos_rel_meas_NED.x, xy_pos_var);
float NIS_y = _ekf_y.getPosNIS(_target_pos_rel_meas_NED.y, xy_pos_var);
if (MAX(NIS_x, NIS_y) < 3.0f || _outlier_reject_count >= 3) {
_outlier_reject_count = 0;
_ekf_x.fusePos(_target_pos_rel_meas_NED.x, xy_pos_var);
_ekf_y.fusePos(_target_pos_rel_meas_NED.y, xy_pos_var);
_last_update_ms = AP_HAL::millis();
} else {
_outlier_reject_count++;
}
}
}
// check EKF was properly initialized when the sensor detected a landing target
check_ekf_init_timeout();
// Output prediction
if (target_acquired()) {
_target_pos_rel_est_NE.x = _ekf_x.getPos();
_target_pos_rel_est_NE.y = _ekf_y.getPos();
_target_vel_rel_est_NE.x = _ekf_x.getVel();
_target_vel_rel_est_NE.y = _ekf_y.getVel();
run_output_prediction();
}
break;
}
}
}
// check if EKF got the time to initialize when the landing target was first detected
// Expects sensor to update within EKF_INIT_SENSOR_MIN_UPDATE_MS milliseconds till EKF_INIT_TIME_MS milliseconds have passed
// after this period landing target estimates can be used by vehicle
void AC_PrecLand::check_ekf_init_timeout()
{
if (!target_acquired() && _estimator_initialized) {
// we have just got the target in sight
if (AP_HAL::millis()-_last_update_ms > EKF_INIT_SENSOR_MIN_UPDATE_MS) {
// we have lost the target, not enough readings to initialize the EKF
_estimator_initialized = false;
gcs().send_text(MAV_SEVERITY_CRITICAL, "PrecLand: Init Failed");
} else if (AP_HAL::millis()-_estimator_init_ms > EKF_INIT_TIME_MS) {
// the target has been visible for a while, EKF should now have initialized to a good value
_target_acquired = true;
gcs().send_text(MAV_SEVERITY_INFO, "PrecLand: Init Complete");
}
}
}
bool AC_PrecLand::retrieve_los_meas(Vector3f& target_vec_unit_body)
{
if (_backend->have_los_meas() && _backend->los_meas_time_ms() != _last_backend_los_meas_ms) {
_last_backend_los_meas_ms = _backend->los_meas_time_ms();
_backend->get_los_body(target_vec_unit_body);
if (!is_zero(_yaw_align)) {
// Apply sensor yaw alignment rotation
target_vec_unit_body.rotate_xy(radians(_yaw_align*0.01f));
}
// rotate vector based on sensor oriention to get correct body frame vector
if (_orient != ROTATION_PITCH_270) {
// by default, the vector is constructed downwards in body frame
// hence, we do not do any rotation if the orientation is downwards
// if it is some other orientation, we first bring the vector to forward
// and then we rotate it to desired orientation
// because the rotations are measured with respect to a vector pointing towards front in body frame
// for eg, if orientation is back, i.e., ROTATION_YAW_180,
// the vector is first brought to front and then rotation by YAW 180 to take it to the back of vehicle
target_vec_unit_body.rotate(ROTATION_PITCH_90); // bring vector to front
target_vec_unit_body.rotate(_orient); // rotate it to desired orientation
}
return true;
} else {
return false;
}
}
bool AC_PrecLand::construct_pos_meas_using_rangefinder(float rangefinder_alt_m, bool rangefinder_alt_valid)
{
Vector3f target_vec_unit_body;
if (retrieve_los_meas(target_vec_unit_body)) {
const struct inertial_data_frame_s *inertial_data_delayed = (*_inertial_history)[0];
const bool target_vec_valid = target_vec_unit_body.projected(_approach_vector_body).dot(_approach_vector_body) > 0.0f;
const Vector3f target_vec_unit_ned = inertial_data_delayed->Tbn * target_vec_unit_body;
const Vector3f approach_vector_NED = inertial_data_delayed->Tbn * _approach_vector_body;
const bool alt_valid = (rangefinder_alt_valid && rangefinder_alt_m > 0.0f) || (_backend->distance_to_target() > 0.0f);
if (target_vec_valid && alt_valid) {
// distance to target and distance to target along approach vector
float dist_to_target, dist_to_target_along_av;
// figure out ned camera orientation w.r.t its offset
Vector3f cam_pos_ned;
if (!_cam_offset.get().is_zero()) {
// user has specifed offset for camera
// take its height into account while calculating distance
cam_pos_ned = inertial_data_delayed->Tbn * _cam_offset;
}
if (_backend->distance_to_target() > 0.0f) {
// sensor has provided distance to landing target
dist_to_target = _backend->distance_to_target();
} else {
// sensor only knows the horizontal location of the landing target
// rely on rangefinder for the vertical target
dist_to_target_along_av = MAX(rangefinder_alt_m - cam_pos_ned.projected(approach_vector_NED).length(), 0.0f);
dist_to_target = dist_to_target_along_av / target_vec_unit_ned.projected(approach_vector_NED).length();
}
// Compute camera position relative to IMU
const Vector3f accel_pos_ned = inertial_data_delayed->Tbn * AP::ins().get_imu_pos_offset(AP::ahrs().get_primary_accel_index());
const Vector3f cam_pos_ned_rel_imu = cam_pos_ned - accel_pos_ned;
// Compute target position relative to IMU
_target_pos_rel_meas_NED = (target_vec_unit_ned * dist_to_target) + cam_pos_ned_rel_imu;
// store the current relative down position so that if we need to retry landing, we know at this height landing target can be found
const AP_AHRS &_ahrs = AP::ahrs();
Vector3f pos_NED;
if (_ahrs.get_relative_position_NED_origin(pos_NED)) {
_last_target_pos_rel_origin_NED.z = pos_NED.z;
_last_vehicle_pos_NED = pos_NED;
}
return true;
}
}
return false;
}
void AC_PrecLand::run_output_prediction()
{
_target_pos_rel_out_NE = _target_pos_rel_est_NE;
_target_vel_rel_out_NE = _target_vel_rel_est_NE;
// Predict forward from delayed time horizon
for (uint8_t i=1; i<_inertial_history->available(); i++) {
const struct inertial_data_frame_s *inertial_data = (*_inertial_history)[i];
_target_vel_rel_out_NE.x -= inertial_data->correctedVehicleDeltaVelocityNED.x;
_target_vel_rel_out_NE.y -= inertial_data->correctedVehicleDeltaVelocityNED.y;
_target_pos_rel_out_NE.x += _target_vel_rel_out_NE.x * inertial_data->dt;
_target_pos_rel_out_NE.y += _target_vel_rel_out_NE.y * inertial_data->dt;
}
const AP_AHRS &_ahrs = AP::ahrs();
const Matrix3f& Tbn = (*_inertial_history)[_inertial_history->available()-1]->Tbn;
Vector3f accel_body_offset = AP::ins().get_imu_pos_offset(_ahrs.get_primary_accel_index());
// Apply position correction for CG offset from IMU
Vector3f imu_pos_ned = Tbn * accel_body_offset;
_target_pos_rel_out_NE.x += imu_pos_ned.x;
_target_pos_rel_out_NE.y += imu_pos_ned.y;
// Apply position correction for body-frame horizontal camera offset from CG, so that vehicle lands lens-to-target
Vector3f cam_pos_horizontal_ned = Tbn * Vector3f(_cam_offset.get().x, _cam_offset.get().y, 0);
_target_pos_rel_out_NE.x -= cam_pos_horizontal_ned.x;
_target_pos_rel_out_NE.y -= cam_pos_horizontal_ned.y;
// Apply velocity correction for IMU offset from CG
Vector3f vel_ned_rel_imu = Tbn * (_ahrs.get_gyro() % (-accel_body_offset));
_target_vel_rel_out_NE.x -= vel_ned_rel_imu.x;
_target_vel_rel_out_NE.y -= vel_ned_rel_imu.y;
// Apply land offset
Vector3f land_ofs_ned_m = _ahrs.get_rotation_body_to_ned() * Vector3f(_land_ofs_cm_x,_land_ofs_cm_y,0) * 0.01f;
_target_pos_rel_out_NE.x += land_ofs_ned_m.x;
_target_pos_rel_out_NE.y += land_ofs_ned_m.y;
// store the landing target as a offset from current position. This is used in landing retry
Vector2f last_target_loc_rel_origin_2d;
get_target_position_cm(last_target_loc_rel_origin_2d);
_last_target_pos_rel_origin_NED.x = last_target_loc_rel_origin_2d.x * 0.01f;
_last_target_pos_rel_origin_NED.y = last_target_loc_rel_origin_2d.y * 0.01f;
// record the last time there was a target output
_last_valid_target_ms = AP_HAL::millis();
}
// Write a precision landing entry
void AC_PrecLand::Write_Precland()
{
// exit immediately if not enabled
if (!enabled()) {
return;
}
Vector3f target_pos_meas;
Vector2f target_pos_rel;
Vector2f target_vel_rel;
get_target_position_relative_cm(target_pos_rel);
get_target_velocity_relative_cms(target_vel_rel);
get_target_position_measurement_cm(target_pos_meas);
const struct log_Precland pkt {
LOG_PACKET_HEADER_INIT(LOG_PRECLAND_MSG),
time_us : AP_HAL::micros64(),
healthy : healthy(),
target_acquired : target_acquired(),
pos_x : target_pos_rel.x,
pos_y : target_pos_rel.y,
vel_x : target_vel_rel.x,
vel_y : target_vel_rel.y,
meas_x : target_pos_meas.x,
meas_y : target_pos_meas.y,
meas_z : target_pos_meas.z,
last_meas : last_backend_los_meas_ms(),
ekf_outcount : ekf_outlier_count(),
estimator : (uint8_t)_estimator_type
};
AP::logger().WriteBlock(&pkt, sizeof(pkt));
}
// singleton instance
AC_PrecLand *AC_PrecLand::_singleton;
namespace AP {
AC_PrecLand *ac_precland()
{
return AC_PrecLand::get_singleton();
}
}
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