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>
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#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"
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#include <AP_AHRS/AP_AHRS.h>
extern const AP_HAL::HAL& hal;
const AP_Param::GroupInfo AC_PrecLand::var_info[] = {
// @Param: ENABLED
// @DisplayName: Precision Land enabled/disabled and behaviour
// @Description: Precision Land enabled/disabled and behaviour
// @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: 0 360
// @Increment: 1
// @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),
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// @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
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AP_GROUPINFO("ACC_P_NSE", 6, AC_PrecLand, _accel_noise, 2.5f),
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// @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)
AP_GROUPEND
};
// Default constructor.
// Note that the Vector/Matrix constructors already implicitly zero
// their values.
//
AC_PrecLand::AC_PrecLand()
{
// set parameters to defaults
AP_Param::setup_object_defaults(this, var_info);
}
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// 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;
}
// default health to false
_backend = nullptr;
_backend_state.healthy = false;
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// create inertial history buffer
// constrain lag parameter to be within bounds
_lag = 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 ((enum PrecLandType)(_type.get())) {
// no type defined
case PRECLAND_TYPE_NONE:
default:
return;
// companion computer
case PRECLAND_TYPE_COMPANION:
_backend = new AC_PrecLand_Companion(*this, _backend_state);
break;
// IR Lock
case PRECLAND_TYPE_IRLOCK:
_backend = new AC_PrecLand_IRLock(*this, _backend_state);
break;
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
case PRECLAND_TYPE_SITL_GAZEBO:
_backend = new AC_PrecLand_SITL_Gazebo(*this, _backend_state);
break;
case PRECLAND_TYPE_SITL:
_backend = new AC_PrecLand_SITL(*this, _backend_state);
break;
#endif
}
// init backend
if (_backend != nullptr) {
_backend->init();
}
}
// 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 AP_AHRS_NavEKF &_ahrs = AP::ahrs_navekf();
_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);
// update estimator of target position
if (_backend != nullptr && _enabled) {
_backend->update();
run_estimator(rangefinder_alt_cm*0.01f, rangefinder_alt_valid);
}
const uint32_t now = AP_HAL::millis();
if (now - last_log_ms > 40) { // 25Hz
last_log_ms = now;
Write_Precland();
}
}
bool AC_PrecLand::target_acquired()
{
_target_acquired = _target_acquired && (AP_HAL::millis()-_last_update_ms) < 2000;
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;
}
// 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 (_estimator_type) {
case ESTIMATOR_TYPE_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)) {
_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 ESTIMATOR_TYPE_KALMAN_FILTER: {
// Predict
if (target_acquired()) {
const float& dt = inertial_data_delayed->dt;
const Vector3f& vehicleDelVel = inertial_data_delayed->correctedVehicleDeltaVelocityNED;
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_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 (!target_acquired()) {
// 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();
_target_acquired = 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();
_target_acquired = true;
} else {
_outlier_reject_count++;
}
}
}
// 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;
}
}
}
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);
// Apply sensor yaw alignment rotation
float sin_yaw_align = sinf(radians(_yaw_align*0.01f));
float cos_yaw_align = cosf(radians(_yaw_align*0.01f));
Matrix3f Rz = Matrix3f(
cos_yaw_align, -sin_yaw_align, 0,
sin_yaw_align, cos_yaw_align, 0,
0, 0, 1
);
target_vec_unit_body = Rz*target_vec_unit_body;
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];
Vector3f target_vec_unit_ned = inertial_data_delayed->Tbn * target_vec_unit_body;
bool target_vec_valid = target_vec_unit_ned.z > 0.0f;
bool alt_valid = (rangefinder_alt_valid && rangefinder_alt_m > 0.0f) || (_backend->distance_to_target() > 0.0f);
if (target_vec_valid && alt_valid) {
float dist, alt;
if (_backend->distance_to_target() > 0.0f) {
dist = _backend->distance_to_target();
alt = dist * target_vec_unit_ned.z;
} else {
alt = MAX(rangefinder_alt_m, 0.0f);
dist = alt / target_vec_unit_ned.z;
}
// Compute camera position relative to IMU
Vector3f accel_body_offset = AP::ins().get_imu_pos_offset(AP::ahrs().get_primary_accel_index());
Vector3f cam_pos_ned = inertial_data_delayed->Tbn * (_cam_offset.get() - accel_body_offset);
// Compute target position relative to IMU
_target_pos_rel_meas_NED = Vector3f(target_vec_unit_ned.x*dist, target_vec_unit_ned.y*dist, alt) + cam_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;
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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;
}
// 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 : estimator_type()
};
AP::logger().WriteBlock(&pkt, sizeof(pkt));
}