ardupilot/libraries/AP_InertialNav/AP_InertialNav_NavEKF.cpp

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#include <AP_HAL/AP_HAL.h>
#include "AP_InertialNav.h"
#if AP_AHRS_NAVEKF_AVAILABLE
/*
A wrapper around the AP_InertialNav class which uses the NavEKF
filter if available, and falls back to the AP_InertialNav filter
when EKF is not available
*/
/**
update internal state
*/
void AP_InertialNav_NavEKF::update(float dt)
{
// get the NE position relative to the local earth frame origin
Vector2f posNE;
if (_ahrs_ekf.get_relative_position_NE(posNE)) {
_relpos_cm.x = posNE.x * 100; // convert from m to cm
_relpos_cm.y = posNE.y * 100; // convert from m to cm
}
// get the D position relative to the local earth frame origin
float posD;
if (_ahrs_ekf.get_relative_position_D(posD)) {
_relpos_cm.z = - posD * 100; // convert from m in NED to cm in NEU
}
// get the absolute WGS-84 position
_haveabspos = _ahrs_ekf.get_position(_abspos);
// get the velocity relative to the local earth frame
Vector3f velNED;
if (_ahrs_ekf.get_velocity_NED(velNED)) {
_velocity_cm = velNED * 100; // convert to cm/s
_velocity_cm.z = -_velocity_cm.z; // convert from NED to NEU
}
// Get a derivative of the vertical position which is kinematically consistent with the vertical position is required by some control loops.
// This is different to the vertical velocity from the EKF which is not always consistent with the verical position due to the various errors that are being corrected for.
if (_ahrs_ekf.get_vert_pos_rate(_pos_z_rate)) {
_pos_z_rate *= 100; // convert to cm/s
_pos_z_rate = - _pos_z_rate; // InertialNav is NEU
}
}
/**
* get_filter_status : returns filter status as a series of flags
*/
nav_filter_status AP_InertialNav_NavEKF::get_filter_status() const
{
nav_filter_status status;
_ahrs_ekf.get_filter_status(status);
return status;
}
/**
* get_origin - returns the inertial navigation origin in lat/lon/alt
*/
struct Location AP_InertialNav_NavEKF::get_origin() const
{
struct Location ret;
if (!_ahrs_ekf.get_origin(ret)) {
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// initialise location to all zeros if EKF origin not yet set
memset(&ret, 0, sizeof(ret));
}
return ret;
}
/**
* get_position - returns the current position relative to the home location in cm.
*
* @return
*/
const Vector3f &AP_InertialNav_NavEKF::get_position(void) const
{
return _relpos_cm;
}
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/**
* get_location - updates the provided location with the latest calculated location
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* returns true on success (i.e. the EKF knows it's latest position), false on failure
*/
bool AP_InertialNav_NavEKF::get_location(struct Location &loc) const
{
return _ahrs_ekf.get_location(loc);
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}
/**
* get_latitude - returns the latitude of the current position estimation in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
*/
int32_t AP_InertialNav_NavEKF::get_latitude() const
{
return _abspos.lat;
}
/**
* get_longitude - returns the longitude of the current position estimation in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
* @return
*/
int32_t AP_InertialNav_NavEKF::get_longitude() const
{
return _abspos.lng;
}
/**
* get_velocity - returns the current velocity in cm/s
*
* @return velocity vector:
* .x : latitude velocity in cm/s
* .y : longitude velocity in cm/s
* .z : vertical velocity in cm/s
*/
const Vector3f &AP_InertialNav_NavEKF::get_velocity() const
{
return _velocity_cm;
}
/**
* get_velocity_xy - returns the current horizontal velocity in cm/s
*
* @returns the current horizontal velocity in cm/s
*/
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float AP_InertialNav_NavEKF::get_velocity_xy() const
{
return norm(_velocity_cm.x, _velocity_cm.y);
}
/**
* get_pos_z_derivative - returns the derivative of the z position in cm/s
*/
float AP_InertialNav_NavEKF::get_pos_z_derivative() const
{
return _pos_z_rate;
}
/**
* get_altitude - get latest altitude estimate in cm
* @return
*/
float AP_InertialNav_NavEKF::get_altitude() const
{
return _relpos_cm.z;
}
/**
* getHgtAboveGnd - get latest height above ground level estimate in cm and a validity flag
*
* @return
*/
bool AP_InertialNav_NavEKF::get_hagl(float &height) const
{
// true when estimate is valid
bool valid = _ahrs_ekf.get_hagl(height);
// convert height from m to cm
height *= 100.0f;
return valid;
}
/**
* get_hgt_ctrl_limit - get maximum height to be observed by the control loops in cm and a validity flag
* this is used to limit height during optical flow navigation
* it will return invalid when no limiting is required
* @return
*/
bool AP_InertialNav_NavEKF::get_hgt_ctrl_limit(float& limit) const
{
// true when estimate is valid
if (_ahrs_ekf.get_hgt_ctrl_limit(limit)) {
// convert height from m to cm
limit *= 100.0f;
return true;
}
return false;
}
/**
* get_velocity_z - returns the current climbrate.
*
* @see get_velocity().z
*
* @return climbrate in cm/s
*/
float AP_InertialNav_NavEKF::get_velocity_z() const
{
return _velocity_cm.z;
}
#endif // AP_AHRS_NAVEKF_AVAILABLE