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AP_NavEKF: Fall back to attitude and hgt estimation for copter if GPS lost

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priseborough 2014-12-29 11:12:25 +11:00 committed by Randy Mackay
parent b21f9daa90
commit 48cae0df15
1 changed files with 24 additions and 15 deletions
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39
libraries/AP_NavEKF/AP_NavEKF.cpp
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@ -700,10 +700,6 @@ void NavEKF::UpdateFilter()
// check to see if arm status has changed and reset states if it has
if (vehicleArmed != prevVehicleArmed) {
ResetVelocity();
ResetPosition();
ResetHeight();
StoreStatesReset();
// only reset the magnetic field and heading on the first arm. This prevents in-flight learning being forgotten for vehicles that do multiple short flights and disarm in-between.
if (vehicleArmed && !firstArmComplete) {
firstArmComplete = true;
@ -714,7 +710,9 @@ void NavEKF::UpdateFilter()
heldVelNE.zero();
// set various useage modes based on the condition at arming. These are then held until the vehicle is disarmed.
if (!vehicleArmed) {
gpsInhibitMode = 1; // When dis-armed, we only estimate orientation & height
gpsInhibitMode = 1; // When dis-armed, we only estimate orientation & height using the position hold mode
posHoldMode = true;
velHoldMode = false; // always clear velocity hold mode if position hold mode is active
} else if (_fusionModeGPS == 3) { // arming when GPS useage has been prohibited
if (optFlowDataPresent()) {
gpsInhibitMode = 2; // we have optical flow data and can estimate all vehicle states
@ -734,6 +732,12 @@ void NavEKF::UpdateFilter()
gpsInhibitMode = 0; // we have GPS data and can estimate all vehicle states
}
}
// Reset filter positon, height and velocity states on arming or disarming
ResetVelocity();
ResetPosition();
ResetHeight();
StoreStatesReset();
} else if (vehicleArmed && !finalMagYawInit && firstArmPosD - state.position.z > 1.5f && !assume_zero_sideslip()) {
// Do a final yaw and earth mag field initialisation when the vehicle has gained 1.5m of altitude after arming if it is a non-fly forward vehicle (vertical takeoff)
state.quat = calcQuatAndFieldStates(_ahrs->roll, _ahrs->pitch);
@ -744,6 +748,7 @@ void NavEKF::UpdateFilter()
// position hold enables attitude only estimates without GPS by fusing zeros for position
if (gpsInhibitMode == 1) {
posHoldMode = true;
velHoldMode = false; // always clear velocity hold mode if position hold mode is active
} else {
posHoldMode = false;
}
@ -798,6 +803,11 @@ void NavEKF::SelectVelPosFusion()
if (imuSampleTime_ms - lastFixTime_ms > gpsRetryTimeout) {
posTimeout = true;
velTimeout = true;
//If this happens in flight and we don't have airspeed or sideslip assumption to constrain drift, then go into velocity hold mode and stay there until disarmed
if (vehicleArmed && !useAirspeed() && !assume_zero_sideslip()) {
velHoldMode = true;
posHoldMode = false; // always clear position hold mode if velocity hold mode is active
}
}
// command fusion of GPS data and reset states as required
@ -948,8 +958,6 @@ void NavEKF::SelectFlowFusion()
// if we don't have valid flow measurements and are not using GPS, dead reckon using current velocity vector unless we are in positon hold mode mode
if (!flowDataValid && !posHoldMode && gpsInhibitMode == 2) {
velHoldMode = true;
} else {
velHoldMode = false;
}
if (velHoldMode && !lastHoldVelocity) {
heldVelNE.x = state.velocity.x;
@ -2003,10 +2011,10 @@ void NavEKF::FuseVelPosNED()
velTestRatio = innovVelSumSq / (varVelSum * sq(_gpsVelInnovGate));
// fail if the ratio is greater than 1
velHealth = ((velTestRatio < 1.0f) || badIMUdata);
// declare a timeout if we have not fused velocity data for too long
velTimeout = (imuSampleTime_ms - velFailTime) > gpsRetryTime;
// if data is healthy or in position hold mode we fuse it
if (velHealth || posHoldMode || velHoldMode) {
// declare a timeout if we have not fused velocity data for too long or in velocity hold mode
velTimeout = ((imuSampleTime_ms - velFailTime) > gpsRetryTime) || velHoldMode;
// if data is healthy or in velocity hold mode we fuse it
if (velHealth || velHoldMode) {
velHealth = true;
velFailTime = imuSampleTime_ms;
} else if (velTimeout && !posHealth) {
@ -4140,6 +4148,7 @@ void NavEKF::writeOptFlowMeas(uint8_t &rawFlowQuality, Vector2f &rawFlowRates, V
flowRadXYcomp[1] = flowStates[0]*flowRadXY[1] + omegaAcrossFlowTime.y;
// set flag that will trigger observations
newDataFlow = true;
// clear the velocity hold mode now we have good data
velHoldMode = false;
flowValidMeaTime_ms = imuSampleTime_ms;
} else {
@ -4554,16 +4563,16 @@ return filter function status as a bitmasked integer
4 = absolute horizontal position estimate valid
5 = vertical position estimate valid
6 = terrain height estimate valid
7 = positon hold mode
7 = position hold mode
*/
void NavEKF::getFilterStatus(uint8_t &status) const
{
// add code to set bits using private filter data here
status = (!state.quat.is_nan()<<0 | // we can implement a better way to detect invalid attitude, but it is tricky to do reliably
!(velTimeout && tasTimeout)<<1 |
(!(velTimeout && posTimeout && tasTimeout) && !velHoldMode && !posHoldMode)<<1 |
!((velTimeout && hgtTimeout) || (hgtTimeout && _fusionModeGPS > 0))<<2 |
((gpsInhibitMode == 2 && flowDataValid) || (!tasTimeout && assume_zero_sideslip()) || (!posTimeout && gpsInhibitMode == 0))<<3 |
(!posTimeout && gpsInhibitMode == 0)<<4 |
((gpsInhibitMode == 2 && flowDataValid) || (!tasTimeout && assume_zero_sideslip()) || (!posTimeout && gpsInhibitMode == 0) && !velHoldMode && !posHoldMode)<<3 |
((!posTimeout && gpsInhibitMode == 0) && !velHoldMode && !posHoldMode)<<4 |
!hgtTimeout<<5 |
!inhibitGndState<<6 |
posHoldMode<<7);