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AP_NavEKF2: Add fix status to GPS check report message

This commit is contained in:
Paul Riseborough 2015-10-08 16:24:53 -07:00 committed by Randy Mackay
parent ef5049862a
commit db4dfce7b1
3 changed files with 84 additions and 76 deletions
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158
libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
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@ -343,89 +343,95 @@ bool NavEKF2_core::readDeltaVelocity(uint8_t ins_index, Vector3f &dVel, float &d
void NavEKF2_core::readGpsData()
{
// check for new GPS data
if ((_ahrs->get_gps().last_message_time_ms() != lastTimeGpsReceived_ms) &&
(_ahrs->get_gps().status() >= AP_GPS::GPS_OK_FIX_3D))
{
// store fix time from previous read
secondLastGpsTime_ms = lastTimeGpsReceived_ms;
if (_ahrs->get_gps().last_message_time_ms() != lastTimeGpsReceived_ms) {
if (_ahrs->get_gps().status() >= AP_GPS::GPS_OK_FIX_3D) {
// report GPS fix status
gpsCheckStatus.bad_fix = false;
// get current fix time
lastTimeGpsReceived_ms = _ahrs->get_gps().last_message_time_ms();
// store fix time from previous read
secondLastGpsTime_ms = lastTimeGpsReceived_ms;
// estimate when the GPS fix was valid, allowing for GPS processing and other delays
// ideally we should be using a timing signal from the GPS receiver to set this time
gpsDataNew.time_ms = lastTimeGpsReceived_ms - frontend._gpsDelay_ms;
// get current fix time
lastTimeGpsReceived_ms = _ahrs->get_gps().last_message_time_ms();
// read the NED velocity from the GPS
gpsDataNew.vel = _ahrs->get_gps().velocity();
// estimate when the GPS fix was valid, allowing for GPS processing and other delays
// ideally we should be using a timing signal from the GPS receiver to set this time
gpsDataNew.time_ms = lastTimeGpsReceived_ms - frontend._gpsDelay_ms;
// Use the speed accuracy from the GPS if available, otherwise set it to zero.
// Apply a decaying envelope filter with a 5 second time constant to the raw speed accuracy data
float alpha = constrain_float(0.0002f * (lastTimeGpsReceived_ms - secondLastGpsTime_ms),0.0f,1.0f);
gpsSpdAccuracy *= (1.0f - alpha);
float gpsSpdAccRaw;
if (!_ahrs->get_gps().speed_accuracy(gpsSpdAccRaw)) {
gpsSpdAccuracy = 0.0f;
} else {
gpsSpdAccuracy = max(gpsSpdAccuracy,gpsSpdAccRaw);
}
// read the NED velocity from the GPS
gpsDataNew.vel = _ahrs->get_gps().velocity();
// check if we have enough GPS satellites and increase the gps noise scaler if we don't
if (_ahrs->get_gps().num_sats() >= 6 && (PV_AidingMode == AID_ABSOLUTE)) {
gpsNoiseScaler = 1.0f;
} else if (_ahrs->get_gps().num_sats() == 5 && (PV_AidingMode == AID_ABSOLUTE)) {
gpsNoiseScaler = 1.4f;
} else { // <= 4 satellites or in constant position mode
gpsNoiseScaler = 2.0f;
}
// Check if GPS can output vertical velocity and set GPS fusion mode accordingly
if (_ahrs->get_gps().have_vertical_velocity() && frontend._fusionModeGPS == 0) {
useGpsVertVel = true;
} else {
useGpsVertVel = false;
}
// Monitor quality of the GPS velocity data before and after alignment using separate checks
if (PV_AidingMode != AID_ABSOLUTE) {
// Pre-alignment checks
gpsQualGood = calcGpsGoodToAlign();
} else {
// Post-alignment checks
calcGpsGoodForFlight();
}
// read latitutde and longitude from GPS and convert to local NE position relative to the stored origin
// If we don't have an origin, then set it to the current GPS coordinates
const struct Location &gpsloc = _ahrs->get_gps().location();
if (validOrigin) {
gpsDataNew.pos = location_diff(EKF_origin, gpsloc);
} else if (gpsQualGood) {
// Set the NE origin to the current GPS position
setOrigin();
// Now we know the location we have an estimate for the magnetic field declination and adjust the earth field accordingly
alignMagStateDeclination();
// Set the height of the NED origin to ‘height of baro height datum relative to GPS height datum'
EKF_origin.alt = gpsloc.alt - baroDataNew.hgt;
// We are by definition at the origin at the instant of alignment so set NE position to zero
gpsDataNew.pos.zero();
// If GPS useage isn't explicitly prohibited, we switch to absolute position mode
if (isAiding && frontend._fusionModeGPS != 3) {
PV_AidingMode = AID_ABSOLUTE;
// Initialise EKF position and velocity states
ResetPosition();
ResetVelocity();
// Use the speed accuracy from the GPS if available, otherwise set it to zero.
// Apply a decaying envelope filter with a 5 second time constant to the raw speed accuracy data
float alpha = constrain_float(0.0002f * (lastTimeGpsReceived_ms - secondLastGpsTime_ms),0.0f,1.0f);
gpsSpdAccuracy *= (1.0f - alpha);
float gpsSpdAccRaw;
if (!_ahrs->get_gps().speed_accuracy(gpsSpdAccRaw)) {
gpsSpdAccuracy = 0.0f;
} else {
gpsSpdAccuracy = max(gpsSpdAccuracy,gpsSpdAccRaw);
}
// check if we have enough GPS satellites and increase the gps noise scaler if we don't
if (_ahrs->get_gps().num_sats() >= 6 && (PV_AidingMode == AID_ABSOLUTE)) {
gpsNoiseScaler = 1.0f;
} else if (_ahrs->get_gps().num_sats() == 5 && (PV_AidingMode == AID_ABSOLUTE)) {
gpsNoiseScaler = 1.4f;
} else { // <= 4 satellites or in constant position mode
gpsNoiseScaler = 2.0f;
}
// Check if GPS can output vertical velocity and set GPS fusion mode accordingly
if (_ahrs->get_gps().have_vertical_velocity() && frontend._fusionModeGPS == 0) {
useGpsVertVel = true;
} else {
useGpsVertVel = false;
}
// Monitor quality of the GPS velocity data before and after alignment using separate checks
if (PV_AidingMode != AID_ABSOLUTE) {
// Pre-alignment checks
gpsQualGood = calcGpsGoodToAlign();
} else {
// Post-alignment checks
calcGpsGoodForFlight();
}
// read latitutde and longitude from GPS and convert to local NE position relative to the stored origin
// If we don't have an origin, then set it to the current GPS coordinates
const struct Location &gpsloc = _ahrs->get_gps().location();
if (validOrigin) {
gpsDataNew.pos = location_diff(EKF_origin, gpsloc);
} else if (gpsQualGood) {
// Set the NE origin to the current GPS position
setOrigin();
// Now we know the location we have an estimate for the magnetic field declination and adjust the earth field accordingly
alignMagStateDeclination();
// Set the height of the NED origin to ‘height of baro height datum relative to GPS height datum'
EKF_origin.alt = gpsloc.alt - baroDataNew.hgt;
// We are by definition at the origin at the instant of alignment so set NE position to zero
gpsDataNew.pos.zero();
// If GPS useage isn't explicitly prohibited, we switch to absolute position mode
if (isAiding && frontend._fusionModeGPS != 3) {
PV_AidingMode = AID_ABSOLUTE;
// Initialise EKF position and velocity states
ResetPosition();
ResetVelocity();
}
}
// calculate a position offset which is applied to NE position and velocity wherever it is used throughout code to allow GPS position jumps to be accommodated gradually
decayGpsOffset();
// save measurement to buffer to be fused later
StoreGPS();
// declare GPS available for use
gpsNotAvailable = false;
} else {
// report GPS fix status
gpsCheckStatus.bad_fix = true;
}
// calculate a position offset which is applied to NE position and velocity wherever it is used throughout code to allow GPS position jumps to be accommodated gradually
decayGpsOffset();
// save measurement to buffer to be fused later
StoreGPS();
// declare GPS available for use
gpsNotAvailable = false;
}
// We need to handle the case where GPS is lost for a period of time that is too long to dead-reckon

1
libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp
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@ -429,6 +429,7 @@ void NavEKF2_core::getFilterGpsStatus(nav_gps_status &faults) const
faults.flags.bad_hAcc = gpsCheckStatus.bad_hAcc; // reported horizontal position accuracy is insufficient
faults.flags.bad_sats = gpsCheckStatus.bad_sats; // reported number of satellites is insufficient
faults.flags.bad_yaw = gpsCheckStatus.bad_yaw; // EKF heading accuracy is too large for GPS use
faults.flags.bad_fix = gpsCheckStatus.bad_fix; // The GPS cannot provide the 3D fix required
}
// send an EKF_STATUS message to GCS

1
libraries/AP_NavEKF2/AP_NavEKF2_core.h
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@ -824,6 +824,7 @@ private:
bool bad_hAcc:1;
bool bad_sats:1;
bool bad_yaw:1;
bool bad_fix:1;
} gpsCheckStatus;
// states held by magnetomter fusion across time steps