ardupilot/libraries/AP_NavEKF3/AP_NavEKF3_Outputs.cpp

626 lines
24 KiB
C++

#include <AP_HAL/AP_HAL.h>
#include "AP_NavEKF3.h"
#include "AP_NavEKF3_core.h"
#include <AP_DAL/AP_DAL.h>
#include <GCS_MAVLink/GCS.h>
// Check basic filter health metrics and return a consolidated health status
bool NavEKF3_core::healthy(void) const
{
uint16_t faultInt;
getFilterFaults(faultInt);
if (faultInt > 0) {
return false;
}
if (velTestRatio > 1 && posTestRatio > 1 && hgtTestRatio > 1) {
// all three metrics being above 1 means the filter is
// extremely unhealthy.
return false;
}
// Give the filter a second to settle before use
if ((imuSampleTime_ms - ekfStartTime_ms) < 1000 ) {
return false;
}
// position and height innovations must be within limits when on-ground and in a static mode of operation
float horizErrSq = sq(innovVelPos[3]) + sq(innovVelPos[4]);
if (onGround && (PV_AidingMode == AID_NONE) && ((horizErrSq > 1.0f) || (fabsF(hgtInnovFiltState) > 1.0f))) {
return false;
}
// all OK
return true;
}
// Return a consolidated error score where higher numbers represent larger errors
// Intended to be used by the front-end to determine which is the primary EKF
float NavEKF3_core::errorScore() const
{
float score = 0.0f;
if (tiltAlignComplete && yawAlignComplete) {
// Check GPS fusion performance
score = MAX(score, 0.5f * (velTestRatio + posTestRatio));
// Check altimeter fusion performance
score = MAX(score, hgtTestRatio);
// Check airspeed fusion performance - only when we are using at least 2 airspeed sensors so we can switch lanes with
// a better one. This only comes into effect for a forward flight vehicle. A sensitivity factor of 0.3 is added to keep the
// EKF less sensitive to innovations arising due events like strong gusts of wind, thus, prevent reporting high error scores
if (assume_zero_sideslip()) {
const auto *arsp = dal.airspeed();
if (arsp != nullptr && arsp->get_num_sensors() >= 2 && (frontend->_affinity & EKF_AFFINITY_ARSP)) {
score = MAX(score, 0.3f * tasTestRatio);
}
}
// Check magnetometer fusion performance - need this when magnetometer affinity is enabled to override the inherent compass
// switching mechanism, and instead be able to move to a better lane
if (frontend->_affinity & EKF_AFFINITY_MAG) {
score = MAX(score, 0.3f * (magTestRatio.x + magTestRatio.y + magTestRatio.z));
}
}
return score;
}
// provides the height limit to be observed by the control loops
// returns false if no height limiting is required
// this is needed to ensure the vehicle does not fly too high when using optical flow navigation
bool NavEKF3_core::getHeightControlLimit(float &height) const
{
// only ask for limiting if we are doing optical flow navigation
if (frontend->sources.useVelXYSource(AP_NavEKF_Source::SourceXY::OPTFLOW) && (PV_AidingMode == AID_RELATIVE) && flowDataValid) {
// If are doing optical flow nav, ensure the height above ground is within range finder limits after accounting for vehicle tilt and control errors
const auto *_rng = dal.rangefinder();
if (_rng == nullptr) {
// we really, really shouldn't be here.
return false;
}
height = MAX(float(_rng->max_distance_cm_orient(ROTATION_PITCH_270)) * 0.007f - 1.0f, 1.0f);
// If we are are not using the range finder as the height reference, then compensate for the difference between terrain and EKF origin
if (frontend->sources.getPosZSource() != AP_NavEKF_Source::SourceZ::RANGEFINDER) {
height -= terrainState;
}
return true;
} else {
return false;
}
}
// return the Euler roll, pitch and yaw angle in radians
void NavEKF3_core::getEulerAngles(Vector3f &euler) const
{
outputDataNew.quat.to_euler(euler.x, euler.y, euler.z);
euler = euler - dal.get_trim();
}
// return body axis gyro bias estimates in rad/sec
void NavEKF3_core::getGyroBias(Vector3f &gyroBias) const
{
if (dtEkfAvg < 1e-6f) {
gyroBias.zero();
return;
}
gyroBias = (stateStruct.gyro_bias / dtEkfAvg).tofloat();
}
// return accelerometer bias in m/s/s
void NavEKF3_core::getAccelBias(Vector3f &accelBias) const
{
if (!statesInitialised) {
accelBias.zero();
return;
}
accelBias = (stateStruct.accel_bias / dtEkfAvg).tofloat();
}
// return the transformation matrix from XYZ (body) to NED axes
void NavEKF3_core::getRotationBodyToNED(Matrix3f &mat) const
{
outputDataNew.quat.rotation_matrix(mat);
mat = mat * dal.get_rotation_vehicle_body_to_autopilot_body();
}
// return the quaternions defining the rotation from NED to XYZ (body) axes
void NavEKF3_core::getQuaternion(Quaternion& ret) const
{
ret = outputDataNew.quat.tofloat();
}
// return the amount of yaw angle change due to the last yaw angle reset in radians
// returns the time of the last yaw angle reset or 0 if no reset has ever occurred
uint32_t NavEKF3_core::getLastYawResetAngle(float &yawAng) const
{
yawAng = yawResetAngle;
return lastYawReset_ms;
}
// return the amount of NE position change due to the last position reset in metres
// returns the time of the last reset or 0 if no reset has ever occurred
uint32_t NavEKF3_core::getLastPosNorthEastReset(Vector2f &pos) const
{
pos = posResetNE.tofloat();
return lastPosReset_ms;
}
// return the amount of vertical position change due to the last vertical position reset in metres
// returns the time of the last reset or 0 if no reset has ever occurred
uint32_t NavEKF3_core::getLastPosDownReset(float &posD) const
{
posD = posResetD;
return lastPosResetD_ms;
}
// return the amount of NE velocity change due to the last velocity reset in metres/sec
// returns the time of the last reset or 0 if no reset has ever occurred
uint32_t NavEKF3_core::getLastVelNorthEastReset(Vector2f &vel) const
{
vel = velResetNE.tofloat();
return lastVelReset_ms;
}
// return the NED wind speed estimates in m/s (positive is air moving in the direction of the axis)
// returns true if wind state estimation is active
bool NavEKF3_core::getWind(Vector3f &wind) const
{
wind.x = stateStruct.wind_vel.x;
wind.y = stateStruct.wind_vel.y;
wind.z = 0.0f; // currently don't estimate this
return !inhibitWindStates;
}
// return the NED velocity of the body frame origin in m/s
//
void NavEKF3_core::getVelNED(Vector3f &vel) const
{
// correct for the IMU position offset (EKF calculations are at the IMU)
vel = (outputDataNew.velocity + velOffsetNED).tofloat();
}
// return estimate of true airspeed vector in body frame in m/s
// returns false if estimate is unavailable
bool NavEKF3_core::getAirSpdVec(Vector3f &vel) const
{
if (inhibitWindStates || PV_AidingMode == AID_NONE) {
return false;
}
vel = (outputDataNew.velocity + velOffsetNED).tofloat();
vel.x -= stateStruct.wind_vel.x;
vel.y -= stateStruct.wind_vel.y;
Matrix3f Tnb; // rotation from nav to body frame
outputDataNew.quat.inverse().rotation_matrix(Tnb);
vel = Tnb * vel;
return true;
}
// Return the rate of change of vertical position in the down direction (dPosD/dt) of the body frame origin in m/s
float NavEKF3_core::getPosDownDerivative(void) const
{
// return the value calculated from a complementary filter applied to the EKF height and vertical acceleration
// correct for the IMU offset (EKF calculations are at the IMU)
return vertCompFiltState.vel + velOffsetNED.z;
}
// Write the last estimated NE position of the body frame origin relative to the reference point (m).
// Return true if the estimate is valid
bool NavEKF3_core::getPosNE(Vector2f &posNE) const
{
// There are three modes of operation, absolute position (GPS fusion), relative position (optical flow fusion) and constant position (no position estimate available)
if (PV_AidingMode != AID_NONE) {
// This is the normal mode of operation where we can use the EKF position states
// correct for the IMU offset (EKF calculations are at the IMU)
posNE = (outputDataNew.position.xy() + posOffsetNED.xy() + public_origin.get_distance_NE_ftype(EKF_origin)).tofloat();
return true;
} else {
// In constant position mode the EKF position states are at the origin, so we cannot use them as a position estimate
if(validOrigin) {
auto &gps = dal.gps();
if ((gps.status(selected_gps) >= AP_DAL_GPS::GPS_OK_FIX_2D)) {
// If the origin has been set and we have GPS, then return the GPS position relative to the origin
const struct Location &gpsloc = gps.location(selected_gps);
posNE = public_origin.get_distance_NE_ftype(gpsloc).tofloat();
return false;
} else if (rngBcnAlignmentStarted) {
// If we are attempting alignment using range beacon data, then report the position
posNE.x = receiverPos.x;
posNE.y = receiverPos.y;
return false;
} else {
// If no GPS fix is available, all we can do is provide the last known position
posNE = outputDataNew.position.xy().tofloat();
return false;
}
} else {
// If the origin has not been set, then we have no means of providing a relative position
posNE.zero();
return false;
}
}
return false;
}
// Write the last calculated D position of the body frame origin relative to the EKF origin (m).
// Return true if the estimate is valid
bool NavEKF3_core::getPosD(float &posD) const
{
// The EKF always has a height estimate regardless of mode of operation
// Correct for the IMU offset (EKF calculations are at the IMU)
// Also correct for changes to the origin height
if ((frontend->_originHgtMode & (1<<2)) == 0) {
// Any sensor height drift corrections relative to the WGS-84 reference are applied to the origin.
posD = outputDataNew.position.z + posOffsetNED.z;
} else {
// The origin height is static and corrections are applied to the local vertical position
// so that height returned by getLLH() = height returned by getOriginLLH - posD
posD = outputDataNew.position.z + posOffsetNED.z + 0.01f * (float)EKF_origin.alt - (float)ekfGpsRefHgt;
}
// adjust posD for difference between our origin and the public_origin
Location local_origin;
if (getOriginLLH(local_origin)) {
posD += (public_origin.alt - local_origin.alt) * 0.01;
}
// Return the current height solution status
return filterStatus.flags.vert_pos;
}
// return the estimated height of body frame origin above ground level
bool NavEKF3_core::getHAGL(float &HAGL) const
{
HAGL = terrainState - outputDataNew.position.z - posOffsetNED.z;
// If we know the terrain offset and altitude, then we have a valid height above ground estimate
return !hgtTimeout && gndOffsetValid && healthy();
}
// Return the last calculated latitude, longitude and height in WGS-84
// If a calculated location isn't available, return a raw GPS measurement
// The status will return true if a calculation or raw measurement is available
// The getFilterStatus() function provides a more detailed description of data health and must be checked if data is to be used for flight control
bool NavEKF3_core::getLLH(struct Location &loc) const
{
Location origin;
if (getOriginLLH(origin)) {
float posD;
if(getPosD(posD) && PV_AidingMode != AID_NONE) {
// Altitude returned is an absolute altitude relative to the WGS-84 spherioid
loc.set_alt_cm(origin.alt - posD*100.0, Location::AltFrame::ABSOLUTE);
if (filterStatus.flags.horiz_pos_abs || filterStatus.flags.horiz_pos_rel) {
// The EKF is able to provide a position estimate
loc.lat = EKF_origin.lat;
loc.lng = EKF_origin.lng;
loc.offset(outputDataNew.position.x + posOffsetNED.x,
outputDataNew.position.y + posOffsetNED.y);
return true;
} else {
// We have been be doing inertial dead reckoning for too long so use raw GPS if available
if (getGPSLLH(loc)) {
return true;
} else {
// Return the EKF estimate but mark it as invalid
loc.lat = EKF_origin.lat;
loc.lng = EKF_origin.lng;
loc.offset(outputDataNew.position.x + posOffsetNED.x,
outputDataNew.position.y + posOffsetNED.y);
return false;
}
}
} else {
// Return a raw GPS reading if available and the last recorded positon if not
if (getGPSLLH(loc)) {
return true;
} else {
loc.lat = EKF_origin.lat;
loc.lng = EKF_origin.lng;
loc.offset(lastKnownPositionNE.x + posOffsetNED.x,
lastKnownPositionNE.y + posOffsetNED.y);
loc.alt = EKF_origin.alt - lastKnownPositionD*100.0;
return false;
}
}
} else {
// The EKF is not navigating so use raw GPS if available
return getGPSLLH(loc);
}
}
bool NavEKF3_core::getGPSLLH(struct Location &loc) const
{
const auto &gps = dal.gps();
if ((gps.status(selected_gps) >= AP_DAL_GPS::GPS_OK_FIX_3D)) {
loc = gps.location(selected_gps);
return true;
}
return false;
}
// return the horizontal speed limit in m/s set by optical flow sensor limits
// return the scale factor to be applied to navigation velocity gains to compensate for increase in velocity noise with height when using optical flow
void NavEKF3_core::getEkfControlLimits(float &ekfGndSpdLimit, float &ekfNavVelGainScaler) const
{
// If in the last 10 seconds we have received flow data and no odometry data, then we are relying on optical flow
bool relyingOnFlowData = (imuSampleTime_ms - prevBodyVelFuseTime_ms > 1000)
&& (imuSampleTime_ms - flowValidMeaTime_ms <= 10000);
// If relying on optical flow, limit speed to prevent sensor limit being exceeded and adjust
// nav gains to prevent body rate feedback into flow rates destabilising the control loop
if (PV_AidingMode == AID_RELATIVE && relyingOnFlowData) {
// allow 1.0 rad/sec margin for angular motion
ekfGndSpdLimit = MAX((frontend->_maxFlowRate - 1.0f), 0.0f) * MAX((terrainState - stateStruct.position[2]), rngOnGnd);
// use standard gains up to 5.0 metres height and reduce above that
ekfNavVelGainScaler = 4.0f / MAX((terrainState - stateStruct.position[2]),4.0f);
} else {
ekfGndSpdLimit = 400.0f; //return 80% of max filter speed
ekfNavVelGainScaler = 1.0f;
}
}
// return the LLH location of the filters NED origin
bool NavEKF3_core::getOriginLLH(struct Location &loc) const
{
if (validOrigin) {
loc = public_origin;
// report internally corrected reference height if enabled
if ((frontend->_originHgtMode & (1<<2)) == 0) {
loc.alt = (int32_t)(100.0f * (float)ekfGpsRefHgt);
}
}
return validOrigin;
}
// return earth magnetic field estimates in measurement units / 1000
void NavEKF3_core::getMagNED(Vector3f &magNED) const
{
magNED = (stateStruct.earth_magfield * 1000.0f).tofloat();
}
// return body magnetic field estimates in measurement units / 1000
void NavEKF3_core::getMagXYZ(Vector3f &magXYZ) const
{
magXYZ = (stateStruct.body_magfield*1000.0f).tofloat();
}
// return magnetometer offsets
// return true if offsets are valid
bool NavEKF3_core::getMagOffsets(uint8_t mag_idx, Vector3f &magOffsets) const
{
const auto &compass = dal.compass();
if (!compass.available()) {
return false;
}
// compass offsets are valid if we have finalised magnetic field initialisation, magnetic field learning is not prohibited,
// primary compass is valid and state variances have converged
const float maxMagVar = 5E-6f;
bool variancesConverged = (P[19][19] < maxMagVar) && (P[20][20] < maxMagVar) && (P[21][21] < maxMagVar);
if ((mag_idx == magSelectIndex) &&
finalInflightMagInit &&
!inhibitMagStates &&
compass.healthy(magSelectIndex) &&
variancesConverged) {
magOffsets = compass.get_offsets(magSelectIndex) - stateStruct.body_magfield.tofloat()*1000.0;
return true;
} else {
magOffsets = compass.get_offsets(magSelectIndex);
return false;
}
}
// return the index for the active magnetometer
// return the index for the active airspeed
uint8_t NavEKF3_core::getActiveAirspeed() const
{
return (uint8_t)selected_airspeed;
}
// return the innovations for the NED Pos, NED Vel, XYZ Mag and Vtas measurements
bool NavEKF3_core::getInnovations(Vector3f &velInnov, Vector3f &posInnov, Vector3f &magInnov, float &tasInnov, float &yawInnov) const
{
velInnov.x = innovVelPos[0];
velInnov.y = innovVelPos[1];
velInnov.z = innovVelPos[2];
posInnov.x = innovVelPos[3];
posInnov.y = innovVelPos[4];
posInnov.z = innovVelPos[5];
magInnov.x = 1e3f*innovMag[0]; // Convert back to sensor units
magInnov.y = 1e3f*innovMag[1]; // Convert back to sensor units
magInnov.z = 1e3f*innovMag[2]; // Convert back to sensor units
tasInnov = innovVtas;
yawInnov = innovYaw;
return true;
}
// return the synthetic air data drag and sideslip innovations
void NavEKF3_core::getSynthAirDataInnovations(Vector2f &dragInnov, float &betaInnov) const
{
#if EK3_FEATURE_DRAG_FUSION
dragInnov.x = innovDrag[0];
dragInnov.y = innovDrag[1];
betaInnov = innovBeta;
#endif
}
// return the innovation consistency test ratios for the velocity, position, magnetometer and true airspeed measurements
// this indicates the amount of margin available when tuning the various error traps
// also return the delta in position due to the last position reset
bool NavEKF3_core::getVariances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar, Vector2f &offset) const
{
velVar = sqrtF(velTestRatio);
posVar = sqrtF(posTestRatio);
hgtVar = sqrtF(hgtTestRatio);
// If we are using simple compass yaw fusion, populate all three components with the yaw test ratio to provide an equivalent output
magVar.x = sqrtF(MAX(magTestRatio.x,yawTestRatio));
magVar.y = sqrtF(MAX(magTestRatio.y,yawTestRatio));
magVar.z = sqrtF(MAX(magTestRatio.z,yawTestRatio));
tasVar = sqrtF(tasTestRatio);
offset = posResetNE.tofloat();
return true;
}
// get a particular source's velocity innovations
// returns true on success and results are placed in innovations and variances arguments
bool NavEKF3_core::getVelInnovationsAndVariancesForSource(AP_NavEKF_Source::SourceXY source, Vector3f &innovations, Vector3f &variances) const
{
switch (source) {
case AP_NavEKF_Source::SourceXY::GPS:
// check for timeouts
if (dal.millis() - gpsVelInnovTime_ms > 500) {
return false;
}
innovations = gpsVelInnov.tofloat();
variances = gpsVelVarInnov.tofloat();
return true;
#if EK3_FEATURE_EXTERNAL_NAV
case AP_NavEKF_Source::SourceXY::EXTNAV:
// check for timeouts
if (dal.millis() - extNavVelInnovTime_ms > 500) {
return false;
}
innovations = extNavVelInnov.tofloat();
variances = extNavVelVarInnov.tofloat();
return true;
#endif // EK3_FEATURE_EXTERNAL_NAV
case AP_NavEKF_Source::SourceXY::OPTFLOW:
// check for timeouts
if (dal.millis() - flowInnovTime_ms > 500) {
return false;
}
innovations.x = flowInnov[0];
innovations.y = flowInnov[1];
innovations.z = 0;
variances.x = flowVarInnov[0];
variances.y = flowVarInnov[1];
variances.z = 0;
return true;
default:
// variances are not available for this source
return false;
}
// should never get here but just in case
return false;
}
/*
return the filter fault status as a bitmasked integer
0 = quaternions are NaN
1 = velocities are NaN
2 = badly conditioned X magnetometer fusion
3 = badly conditioned Y magnetometer fusion
4 = badly conditioned Z magnetometer fusion
5 = badly conditioned airspeed fusion
6 = badly conditioned synthetic sideslip fusion
7 = filter is not initialised
*/
void NavEKF3_core::getFilterFaults(uint16_t &faults) const
{
faults = (stateStruct.quat.is_nan()<<0 |
stateStruct.velocity.is_nan()<<1 |
faultStatus.bad_xmag<<2 |
faultStatus.bad_ymag<<3 |
faultStatus.bad_zmag<<4 |
faultStatus.bad_airspeed<<5 |
faultStatus.bad_sideslip<<6 |
!statesInitialised<<7);
}
// Return the navigation filter status message
void NavEKF3_core::getFilterStatus(nav_filter_status &status) const
{
status = filterStatus;
}
#if HAL_GCS_ENABLED
// send an EKF_STATUS message to GCS
void NavEKF3_core::send_status_report(GCS_MAVLINK &link) const
{
// prepare flags
uint16_t flags = 0;
if (filterStatus.flags.attitude) {
flags |= EKF_ATTITUDE;
}
if (filterStatus.flags.horiz_vel) {
flags |= EKF_VELOCITY_HORIZ;
}
if (filterStatus.flags.vert_vel) {
flags |= EKF_VELOCITY_VERT;
}
if (filterStatus.flags.horiz_pos_rel) {
flags |= EKF_POS_HORIZ_REL;
}
if (filterStatus.flags.horiz_pos_abs) {
flags |= EKF_POS_HORIZ_ABS;
}
if (filterStatus.flags.vert_pos) {
flags |= EKF_POS_VERT_ABS;
}
if (filterStatus.flags.terrain_alt) {
flags |= EKF_POS_VERT_AGL;
}
if (filterStatus.flags.const_pos_mode) {
flags |= EKF_CONST_POS_MODE;
}
if (filterStatus.flags.pred_horiz_pos_rel) {
flags |= EKF_PRED_POS_HORIZ_REL;
}
if (filterStatus.flags.pred_horiz_pos_abs) {
flags |= EKF_PRED_POS_HORIZ_ABS;
}
if (!filterStatus.flags.initalized) {
flags |= EKF_UNINITIALIZED;
}
if (filterStatus.flags.gps_glitching) {
flags |= (1<<15);
}
// get variances
float velVar = 0, posVar = 0, hgtVar = 0, tasVar = 0;
Vector3f magVar;
Vector2f offset;
getVariances(velVar, posVar, hgtVar, magVar, tasVar, offset);
// Only report range finder normalised innovation levels if the EKF needs the data for primary
// height estimation or optical flow operation. This prevents false alarms at the GCS if a
// range finder is fitted for other applications
float temp = 0;
if (((frontend->_useRngSwHgt > 0) && activeHgtSource == AP_NavEKF_Source::SourceZ::RANGEFINDER) || (PV_AidingMode == AID_RELATIVE && flowDataValid)) {
temp = sqrtF(auxRngTestRatio);
}
const mavlink_ekf_status_report_t packet{
velVar,
posVar,
hgtVar,
fmaxF(fmaxF(magVar.x,magVar.y),magVar.z),
temp,
flags,
tasVar
};
// send message
mavlink_msg_ekf_status_report_send_struct(link.get_chan(), &packet);
}
#endif // HAL_GCS_ENABLED
// report the reason for why the backend is refusing to initialise
const char *NavEKF3_core::prearm_failure_reason(void) const
{
if (gpsGoodToAlign) {
// we are not failing
return nullptr;
}
return prearm_fail_string;
}
// report the number of frames lapsed since the last state prediction
// this is used by other instances to level load
uint8_t NavEKF3_core::getFramesSincePredict(void) const
{
return framesSincePredict;
}