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EKF: Reduce EKF-GSF vulnerability to large yaw gyro bias errors (#831) 

* EKF: Reduce EKF-GSF vulnerability to large yaw gyro bias errors

* Update EKF/ekf_helper.cpp

* EKF: Fix comment typo

Co-authored-by: Roman Bapst <bapstroman@gmail.com>

Co-authored-by: Mathieu Bresciani <brescianimathieu@gmail.com>
Co-authored-by: Roman Bapst <bapstroman@gmail.com>
This commit is contained in:
Paul Riseborough 2020-06-02 17:42:54 +10:00 committed by GitHub
parent d0ddda8917
commit 59183f70ba
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 15 additions and 7 deletions
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10
EKF/EKFGSF_yaw.cpp
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@ -14,8 +14,9 @@ EKFGSF_yaw::EKFGSF_yaw()
}
void EKFGSF_yaw::update(const imuSample& imu_sample,
bool run_EKF, // set to true when flying or movement is suitable for yaw estimation
float airspeed) // true airspeed used for centripetal accel compensation - set to 0 when not required.
bool run_EKF, // set to true when flying or movement is suitable for yaw estimation
float airspeed, // true airspeed used for centripetal accel compensation - set to 0 when not required.
const Vector3f &imu_gyro_bias) // estimated rate gyro bias (rad/sec)
{
// copy to class variables
_delta_ang = imu_sample.delta_ang;
@ -60,6 +61,11 @@ void EKFGSF_yaw::update(const imuSample& imu_sample,
if (!_ekf_gsf_vel_fuse_started) {
initialiseEKFGSF();
ahrsAlignYaw();
// Initialise to gyro bias estimate from main filter because there could be a large
// uncorrected rate gyro bias error about the gravity vector
for (uint8_t model_index = 0; model_index < N_MODELS_EKFGSF; model_index ++) {
_ahrs_ekf_gsf[model_index].gyro_bias = imu_gyro_bias;
}
_ekf_gsf_vel_fuse_started = true;
} else {
bool bad_update = false;

9
EKF/EKFGSF_yaw.h
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@ -31,11 +31,12 @@ public:
// Update Filter States - this should be called whenever new IMU data is available
void update(const imuSample &imu_sample,
bool run_EKF, // set to true when flying or movement is suitable for yaw estimation
float airspeed); // true airspeed used for centripetal accel compensation - set to 0 when not required.
bool run_EKF, // set to true when flying or movement is suitable for yaw estimation
float airspeed, // true airspeed used for centripetal accel compensation - set to 0 when not required.
const Vector3f &imu_gyro_bias); // estimated rate gyro bias (rad/sec)
void setVelocity(const Vector2f &velocity, // NE velocity measurement (m/s)
float accuracy); // 1-sigma accuracy of velocity measurement (m/s)
void setVelocity(const Vector2f &velocity, // NE velocity measurement (m/s)
float accuracy); // 1-sigma accuracy of velocity measurement (m/s)
// get solution data for logging
bool getLogData(float *yaw_composite,

3
EKF/ekf_helper.cpp
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@ -1858,7 +1858,8 @@ void Ekf::runYawEKFGSF()
TAS = _airspeed_sample_delayed.true_airspeed;
}
yawEstimator.update(_imu_sample_delayed, _control_status.flags.in_air, TAS);
const Vector3f imu_gyro_bias = getGyroBias();
yawEstimator.update(_imu_sample_delayed, _control_status.flags.in_air, TAS, imu_gyro_bias);
// basic sanity check on GPS velocity data
if (_gps_data_ready && _gps_sample_delayed.vacc > FLT_EPSILON && ISFINITE(_gps_sample_delayed.vel(0)) && ISFINITE(_gps_sample_delayed.vel(1))) {