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EKF: Add position and velocity innovation consistency checks

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This commit is contained in:
Paul Riseborough
2016-01-28 16:33:54 +11:00
parent 7713cc8c20
commit 9236f11c80
2 changed files with 41 additions and 17 deletions
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EKF/estimator_base.h
+8 -2
View File
@@ -81,11 +81,15 @@ struct parameters {
float gps_vel_noise = 0.05f;
float gps_pos_noise = 1.0f;
float baro_noise = 0.1f;
float baro_innov_gate = 5.0f; // barometer fusion innovation consistency gate size in standard deviations
float velD_innov_gate = 5.0f; // Vertical velocity fusion innovation consistency gate size in standard deviations
float posNE_innov_gate = 5.0f; // Horizontal position innovation consistency gate size in standard deviations
float velNE_innov_gate = 5.0f; // Horizontal velocity fusion innovation consistency gate size in standard deviations
float mag_heading_noise = 3e-2f; // measurement noise used for simple heading fusion
float mag_declination_deg = 0.0f; // magnetic declination in degrees
float heading_innov_gate = 3.0f; // heading fusion innovation consistency gate size in standard deviations
float mag_innov_gate = 3.0f; // magnetometer fusion innovation consistency gate size in standard deviations
float mag_innov_gate = 3.0f; // magnetometer fusion innovation consistency gate size in standard deviations
// these parameters control the strictness of GPS quality checks used to determine uf the GPS is
// good enough to set a local origin and commence aiding
@@ -261,7 +265,9 @@ protected:
float _yaw_test_ratio; // yaw innovation consistency check ratio
float _mag_test_ratio[3]; // magnetometer XYZ innovation consistency check ratios
bool _in_air = true; // indicates if the vehicle is in the air
float _vel_pos_test_ratio[6]; // velocity and position innovation consistency check ratios
bool _in_air = true; // indicates if the vehicle is in the air
RingBuffer<imuSample> _imu_buffer;
RingBuffer<gpsSample> _gps_buffer;
EKF/vel_pos_fusion.cpp
+33 -15
View File
@@ -44,7 +44,9 @@
void Ekf::fuseVelPosHeight()
{
bool fuse_map[6] = {};
float R[6] = {};
bool innov_check_pass_map[6] = {};
float R[6] = {};
float gate_size[6] = {};
float Kfusion[24] = {};
// calculate innovations
@@ -54,13 +56,16 @@ void Ekf::fuseVelPosHeight()
_vel_pos_innov[1] = _state.vel(1) - _gps_sample_delayed.vel(1);
R[0] = _params.gps_vel_noise;
R[1] = _params.gps_vel_noise;
}
gate_size[0] = fmaxf(_params.velNE_innov_gate, 1.0f);
gate_size[1] = gate_size[0];
}
if (_fuse_vert_vel) {
fuse_map[2] = true;
_vel_pos_innov[2] = _state.vel(2) - _gps_sample_delayed.vel(2);
R[2] = _params.gps_vel_noise;
}
gate_size[2] = fmaxf(_params.velD_innov_gate, 1.0f);
}
if (_fuse_pos) {
fuse_map[3] = fuse_map[4] = true;
@@ -68,32 +73,45 @@ void Ekf::fuseVelPosHeight()
_vel_pos_innov[4] = _state.pos(1) - _gps_sample_delayed.pos(1);
R[3] = _params.gps_pos_noise;
R[4] = _params.gps_pos_noise;
gate_size[3] = fmaxf(_params.posNE_innov_gate, 1.0f);
gate_size[4] = gate_size[3];
}
if (_fuse_height) {
fuse_map[5] = true;
_vel_pos_innov[5] = _state.pos(2) - (-_baro_sample_delayed.hgt); // baro measurement has inversed z axis
R[5] = _params.baro_noise;
}
gate_size[5] = fmaxf(_params.baro_innov_gate, 1.0f);
}
// XXX Do checks here
// calculate innovation test ratios
for (unsigned obs_index = 0; obs_index < 6; obs_index++) {
if (fuse_map[obs_index]) {
// compute the innovation variance SK = HPH + R
unsigned state_index = obs_index + 3; // we start with vx and this is the 4. state
_vel_pos_innov_var[obs_index] = P[state_index][state_index] + R[obs_index];
// Compute the ratio of innovation to gate size
_vel_pos_test_ratio[obs_index] = sq(_vel_pos_innov[obs_index]) / (sq(gate_size[obs_index]) * _vel_pos_innov[obs_index]);
}
}
for (unsigned obs_index = 0; obs_index < 6; obs_index++) {
if (!fuse_map[obs_index]) {
// check position, velocity and height innovations
// treat 3D velocity, 2D position and height as separate sensors
innov_check_pass_map[2] = innov_check_pass_map[1] = innov_check_pass_map[0] = (_vel_pos_test_ratio[0] <= 1.0f) && (_vel_pos_test_ratio[1] <= 1.0f) && (_vel_pos_test_ratio[2] <= 1.0f);
innov_check_pass_map[4] = innov_check_pass_map[3] = (_vel_pos_test_ratio[3] <= 1.0f) && (_vel_pos_test_ratio[4] <= 1.0f);
innov_check_pass_map[5] = (_vel_pos_test_ratio[5] <= 1.0f);
for (unsigned obs_index = 0; obs_index < 6; obs_index++) {
// skip fusion if not requested or checks have failed
if (!fuse_map[obs_index] || !innov_check_pass_map[obs_index]) {
continue;
}
unsigned state_index = obs_index + 3; // we start with vx and this is the 4. state
// compute the innovation variance SK = HPH + R
float S = P[state_index][state_index] + R[obs_index];
_vel_pos_innov_var[obs_index] = S;
S = 1.0f / S;
// calculate kalman gain K = PHS
// calculate kalman gain K = PHS, where S = 1/innovation variance
for (int row = 0; row < 24; row++) {
Kfusion[row] = P[row][state_index] * S;
Kfusion[row] = P[row][state_index] / _vel_pos_innov_var[obs_index];
}
// by definition the angle error state is zero at the fusion time