ardupilot/libraries/AC_PrecLand/AC_PrecLand.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#include <AP_HAL/AP_HAL.h>
#include "AC_PrecLand.h"
#include "AC_PrecLand_Backend.h"
#include "AC_PrecLand_Companion.h"
#include "AC_PrecLand_IRLock.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 Always Land, 2:Enabled Strict
// @User: Advanced
AP_GROUPINFO("ENABLED", 0, AC_PrecLand, _enabled, 0),
// @Param: TYPE
// @DisplayName: Precision Land Type
// @Description: Precision Land Type
// @Values: 0:None, 1:CompanionComputer, 2:IRLock
// @User: Advanced
AP_GROUPINFO("TYPE", 1, AC_PrecLand, _type, 0),
AP_GROUPEND
};
// Default constructor.
// Note that the Vector/Matrix constructors already implicitly zero
// their values.
//
AC_PrecLand::AC_PrecLand(const AP_AHRS& ahrs, const AP_InertialNav& inav) :
_ahrs(ahrs),
_inav(inav),
_have_estimate(false),
_backend(NULL)
{
// set parameters to defaults
AP_Param::setup_object_defaults(this, var_info);
// other initialisation
_backend_state.healthy = false;
}
// init - perform any required initialisation of backends
void AC_PrecLand::init()
{
// exit immediately if init has already been run
if (_backend != NULL) {
return;
}
// default health to false
_backend = NULL;
_backend_state.healthy = false;
// 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
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4 || CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN
case PRECLAND_TYPE_IRLOCK:
_backend = new AC_PrecLand_IRLock(*this, _backend_state);
break;
#endif
}
// init backend
if (_backend != NULL) {
_backend->init();
}
}
// update - give chance to driver to get updates from sensor
void AC_PrecLand::update(float alt_above_terrain_cm)
{
// run backend update
if (_backend != NULL) {
// read from sensor
_backend->update();
// calculate angles to target and position estimate
calc_angles_and_pos(alt_above_terrain_cm);
}
}
// get_target_shift - returns 3D vector of earth-frame position adjustments to target
Vector3f AC_PrecLand::get_target_shift(const Vector3f &orig_target)
{
Vector3f shift; // default shift initialised to zero
// do not shift target if not enabled or no position estimate
if (_backend == NULL || !_have_estimate) {
return shift;
}
// shift is target_offset - (original target - current position)
Vector3f curr_offset_from_target = orig_target - _inav.get_position();
shift = _target_pos_offset - curr_offset_from_target;
shift.z = 0.0f;
// record we have consumed this reading (perhaps there is a cleaner way to do this using timestamps)
_have_estimate = false;
// return adjusted target
return shift;
}
// calc_angles_and_pos - converts sensor's body-frame angles to earth-frame angles and position estimate
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// raw sensor angles stored in _angle_to_target (might be in earth frame, or maybe body frame)
// earth-frame angles stored in _ef_angle_to_target
// position estimate is stored in _target_pos
void AC_PrecLand::calc_angles_and_pos(float alt_above_terrain_cm)
{
// exit immediately if not enabled
if (_backend == NULL) {
_have_estimate = false;
return;
}
// get angles to target from backend
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if (!_backend->get_angle_to_target(_angle_to_target.x, _angle_to_target.y)) {
_have_estimate = false;
return;
}
float x_rad;
float y_rad;
if(_backend->get_frame_of_reference() == MAV_FRAME_LOCAL_NED){
//don't subtract vehicle lean angles
x_rad = _angle_to_target.x;
y_rad = -_angle_to_target.y;
}else{ // assume MAV_FRAME_BODY_NED (i.e. a hard-mounted sensor)
// subtract vehicle lean angles
x_rad = _angle_to_target.x - _ahrs.roll;
y_rad = -_angle_to_target.y + _ahrs.pitch;
}
// rotate to earth-frame angles
_ef_angle_to_target.x = y_rad*_ahrs.cos_yaw() - x_rad*_ahrs.sin_yaw();
_ef_angle_to_target.y = y_rad*_ahrs.sin_yaw() + x_rad*_ahrs.cos_yaw();
// get current altitude (constrained to no lower than 50cm)
float alt = MAX(alt_above_terrain_cm, 50.0f);
// convert earth-frame angles to earth-frame position offset
_target_pos_offset.x = alt*tanf(_ef_angle_to_target.x);
_target_pos_offset.y = alt*tanf(_ef_angle_to_target.y);
_target_pos_offset.z = 0; // not used
_have_estimate = true;
}
// handle_msg - Process a LANDING_TARGET mavlink message
void AC_PrecLand::handle_msg(mavlink_message_t* msg)
{
// run backend update
if (_backend != NULL) {
_backend->handle_msg(msg);
}
}