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Add helper function to alter heading in rotation matrices

This commit is contained in:
Kamil Ritz 2020-08-15 13:54:21 +02:00 committed by Paul Riseborough
parent fdc86c247a
commit 2be738e806
5 changed files with 33 additions and 44 deletions
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22
EKF/EKFGSF_yaw.cpp
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@ -225,24 +225,14 @@ void EKFGSF_yaw::ahrsAlignYaw()
// Align yaw angle for each model
for (uint8_t model_index = 0; model_index < N_MODELS_EKFGSF; model_index++) {
if (shouldUse321RotationSequence(_ahrs_ekf_gsf[model_index].R)) {
// get the roll, pitch, yaw estimates from the rotation matrix using a 321 Tait-Bryan rotation sequence
Eulerf euler_init(_ahrs_ekf_gsf[model_index].R);
// set the yaw angle
euler_init(2) = wrap_pi(_ekf_gsf[model_index].X(2));
// update the rotation matrix
_ahrs_ekf_gsf[model_index].R = Dcmf(euler_init);
// update the rotation matrix with 321 rotation sequence
_ahrs_ekf_gsf[model_index].R = updateEuler321YawInRotMat(wrap_pi(_ekf_gsf[model_index].X(2)),
_ahrs_ekf_gsf[model_index].R);
} else {
// Calculate the 312 Tait-Bryan rotation sequence that rotates from earth to body frame
const Vector3f rot312(wrap_pi(_ekf_gsf[model_index].X(2)), // yaw
asinf(_ahrs_ekf_gsf[model_index].R(2, 1)), // roll
atan2f(-_ahrs_ekf_gsf[model_index].R(2, 0),
_ahrs_ekf_gsf[model_index].R(2, 2))); // pitch
// Calculate the body to earth frame rotation matrix
_ahrs_ekf_gsf[model_index].R = taitBryan312ToRotMat(rot312);
// update the rotation matrix with 312 rotation sequence
_ahrs_ekf_gsf[model_index].R = updateEuler312YawInRotMat(wrap_pi(_ekf_gsf[model_index].X(2)),
_ahrs_ekf_gsf[model_index].R);
}
_ahrs_ekf_gsf[model_index].aligned = true;

20
EKF/ekf_helper.cpp
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@ -484,16 +484,11 @@ bool Ekf::resetMagHeading(const Vector3f &mag_init, bool increase_yaw_var, bool
Dcmf R_to_earth;
if (shouldUse321RotationSequence(_R_to_earth)) {
// rolled more than pitched so use 321 rotation order
Eulerf euler321(_state.quat_nominal);
euler321(2) = 0.0f;
R_to_earth = Dcmf(euler321);
R_to_earth = updateEuler321YawInRotMat(0.f, _R_to_earth);
} else {
// pitched more than rolled so use 312 rotation order
const Vector3f rotVec312(0.0f, // yaw
asinf(_R_to_earth(2, 1)), // roll
atan2f(-_R_to_earth(2, 0), _R_to_earth(2, 2))); // pitch
R_to_earth = taitBryan312ToRotMat(rotVec312);
R_to_earth = updateEuler312YawInRotMat(0.f, _R_to_earth);
}
@ -1654,19 +1649,12 @@ void Ekf::resetQuatStateYaw(float yaw, float yaw_variance, bool update_buffer)
// update the rotation matrix using the new yaw value
// determine if a 321 or 312 Euler sequence is best
if (shouldUse321RotationSequence(_R_to_earth)) {
// use a 321 sequence
Eulerf euler321(_R_to_earth);
euler321(2) = yaw;
_R_to_earth = Dcmf(euler321);
_R_to_earth = updateEuler321YawInRotMat(yaw, _R_to_earth);
} else {
// Calculate the 312 Tait-Bryan rotation sequence that rotates from earth to body frame
// We use a 312 sequence as an alternate when there is more pitch tilt than roll tilt
// to avoid gimbal lock
const Vector3f rot312(yaw,
asinf(_R_to_earth(2, 1)),
atan2f(-_R_to_earth(2, 0), _R_to_earth(2, 2)));
_R_to_earth = taitBryan312ToRotMat(rot312);
_R_to_earth = updateEuler312YawInRotMat(yaw, _R_to_earth);
}

19
EKF/mag_fusion.cpp
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@ -702,7 +702,6 @@ void Ekf::fuseHeading()
{
Vector3f mag_earth_pred;
float measured_hdg;
float predicted_hdg;
// Calculate the observation variance
float R_YAW;
@ -725,12 +724,11 @@ void Ekf::fuseHeading()
// determine if a 321 or 312 Euler sequence is best
if (shouldUse321RotationSequence(_R_to_earth)) {
// rolled more than pitched so use 321 rotation order to calculate the observed yaw angle
Eulerf euler321(_state.quat_nominal);
predicted_hdg = euler321(2);
const float predicted_hdg = getEuler321Yaw(_R_to_earth);
if (_control_status.flags.mag_hdg) {
// Set the yaw angle to zero and rotate the measurements into earth frame using the zero yaw angle
euler321(2) = 0.0f;
const Dcmf R_to_earth(euler321);
// Rotate the measurements into earth frame using the zero yaw angle
const Dcmf R_to_earth = updateEuler321YawInRotMat(0.f, _R_to_earth);
if (_control_status.flags.mag_3D) {
// don't apply bias corrections if we are learning them
mag_earth_pred = R_to_earth * _mag_sample_delayed.mag;
@ -788,12 +786,9 @@ void Ekf::fuseHeading()
if (_control_status.flags.mag_hdg) {
// Calculate the body to earth frame rotation matrix from the euler angles using a 312 rotation sequence
// with yaw angle set to to zero
const Vector3f rotVec312(0.0f, // yaw
asinf(_R_to_earth(2, 1)), // roll
atan2f(-_R_to_earth(2, 0), _R_to_earth(2, 2))); // pitch
const Dcmf R_to_earth = taitBryan312ToRotMat(rotVec312);
// Calculate the body to earth frame rotation matrix from the euler angles
// using a 312 rotation sequence with yaw angle set to to zero
const Dcmf R_to_earth = updateEuler312YawInRotMat(0.f, _R_to_earth);
// rotate the magnetometer measurements into earth frame using a zero yaw angle
if (_control_status.flags.mag_3D) {

13
EKF/utils.cpp
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@ -86,3 +86,16 @@ float getEuler312Yaw(const matrix::Quatf& q) {
float getEuler312Yaw(const matrix::Dcmf& R) {
return atan2f(-R(0, 1), R(1, 1));
}
matrix::Dcmf updateEuler321YawInRotMat(float yaw, const matrix::Dcmf& rot_in) {
matrix::Eulerf euler321(rot_in);
euler321(2) = yaw;
return matrix::Dcmf(euler321);
}
matrix::Dcmf updateEuler312YawInRotMat(float yaw, const matrix::Dcmf& rot_in) {
const matrix::Vector3f rotVec312(yaw, // yaw
asinf(rot_in(2, 1)), // roll
atan2f(-rot_in(2, 0), rot_in(2, 2))); // pitch
return taitBryan312ToRotMat(rotVec312);
}

3
EKF/utils.hpp
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@ -31,6 +31,9 @@ float getEuler321Yaw(const matrix::Dcmf& R);
float getEuler312Yaw(const matrix::Quatf& q);
float getEuler312Yaw(const matrix::Dcmf& R);
matrix::Dcmf updateEuler321YawInRotMat(float yaw, const matrix::Dcmf& rot_in);
matrix::Dcmf updateEuler312YawInRotMat(float yaw, const matrix::Dcmf& rot_in);
namespace ecl{
inline float powf(float x, int exp)
{