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EKF: Improve protection against bad airspeed fusion

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This commit is contained in:
Paul Riseborough 2016-05-07 14:23:38 +10:00
parent c8d95586e7
commit 1126048a93
1 changed files with 33 additions and 8 deletions
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41
EKF/airspeed_fusion.cpp
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@ -143,9 +143,6 @@ void Ekf::fuseAirspeed()
// airspeed measurement sample has passed check so record it
_time_last_arsp_fuse = _time_last_imu;
// Fuse airspeed measurement
fuse(Kfusion, _airspeed_innov); //Why calculate angle error when it is always zero?
// update covariance matrix via Pnew = (I - KH)P = P - KHP
for (unsigned row = 0; row < _k_num_states; row++) {
for (unsigned column = 0; column < _k_num_states; column++) { // Here it will be a lot of zeros, should optimize that...
@ -161,13 +158,41 @@ void Ekf::fuseAirspeed()
}
}
for (unsigned row = 0; row < _k_num_states; row++) {
for (unsigned column = 0; column < _k_num_states; column++) {
P[row][column] = P[row][column] - KHP[row][column];
// if the covariance correction will result in a negative variance, then
// the covariance marix is unhealthy and must be corrected
bool healthy = true;
_fault_status.bad_airspeed = false;
for (int i = 0; i < _k_num_states; i++) {
if (P[i][i] < KHP[i][i]) {
// zero rows and columns
zeroRows(P,i,i);
zeroCols(P,i,i);
//flag as unhealthy
healthy = false;
// update individual measurement health status
_fault_status.bad_airspeed = true;
}
}
makeSymmetrical();
limitCov();
// only apply covariance and state corrrections if healthy
if (healthy) {
// apply the covariance corrections
for (unsigned row = 0; row < _k_num_states; row++) {
for (unsigned column = 0; column < _k_num_states; column++) {
P[row][column] = P[row][column] - KHP[row][column];
}
}
// correct the covariance marix for gross errors
makeSymmetrical();
limitCov();
// apply the state corrections
fuse(Kfusion, _airspeed_innov);
}
}
}