Moving drift compensation before computing covariance in c++ library

- Moving drift compensation before computing noise covariance as this
provides marginal improvement in orientation estimation.

Change-Id: Ic236f8400203e70d9b870186c8e098c4bcc8395f

diff --git a/src/sensor_fusion/orientation_filter.cpp b/src/sensor_fusion/orientation_filter.cpp
index 67ff072..ef2e228 100644 (file)
--- a/src/sensor_fusion/orientation_filter.cpp
+++ b/src/sensor_fusion/orientation_filter.cpp
@@ -148,6 +148,32 @@ inline void orientation_filter<TYPE>::compute_covariance()
 {
        TYPE var_gyr_x, var_gyr_y, var_gyr_z;
        TYPE var_roll, var_pitch, var_azimuth;
+       quaternion<TYPE> quat_diff, quat_error;
+
+       if(!is_initialized(m_quat_driv.m_quat))
+               m_quat_driv = m_quat_aid;
+
+       quaternion<TYPE> quat_rot_inc(0, m_gyro.m_data.m_vec[0], m_gyro.m_data.m_vec[1],
+                       m_gyro.m_data.m_vec[2]);
+
+       quat_diff = (m_quat_driv * quat_rot_inc) * (TYPE) 0.5;
+
+       m_quat_driv = m_quat_driv + (quat_diff * (TYPE) m_gyro_dt * (TYPE) PI);
+       m_quat_driv.quat_normalize();
+
+       m_quat_output = phase_correction(m_quat_driv, m_quat_aid);
+
+       m_orientation = quat2euler(m_quat_output);
+
+       quat_error = m_quat_aid * m_quat_driv;
+
+       m_euler_error = (quat2euler(quat_error)).m_ang;
+
+       m_gyro.m_data = m_gyro.m_data - m_euler_error.m_ang;
+
+       m_euler_error.m_ang = m_euler_error.m_ang / (TYPE) PI;
+
+       m_gyro_bias = m_euler_error.m_ang * (TYPE) PI;
 
        insert_end(m_var_gyr_x, m_gyro.m_data.m_vec[0]);
        insert_end(m_var_gyr_y, m_gyro.m_data.m_vec[1]);
@@ -178,8 +204,6 @@ inline void orientation_filter<TYPE>::compute_covariance()
 template <typename TYPE>
 inline void orientation_filter<TYPE>::time_update()
 {
-       quaternion<TYPE> quat_diff, quat_error, quat_output;
-       euler_angles<TYPE> euler_error;
        euler_angles<TYPE> orientation;
 
        m_tran_mat.m_mat[0][1] = m_gyro.m_data.m_vec[2];
@@ -210,43 +234,22 @@ inline void orientation_filter<TYPE>::time_update()
                        m_state_new.m_vec[j] = NEGLIGIBLE_VAL;
        }
 
-       if(!is_initialized(m_quat_driv.m_quat))
-               m_quat_driv = m_quat_aid;
-
-       quaternion<TYPE> quat_rot_inc(0, m_gyro.m_data.m_vec[0], m_gyro.m_data.m_vec[1],
-                       m_gyro.m_data.m_vec[2]);
-
-       quat_diff = (m_quat_driv * quat_rot_inc) * (TYPE) 0.5;
-
-       m_quat_driv = m_quat_driv + (quat_diff * (TYPE) m_gyro_dt * (TYPE) PI);
-       m_quat_driv.quat_normalize();
-
-       quat_output = phase_correction(m_quat_driv, m_quat_aid);
-
-       m_quat_9axis = quat_output;
+       m_quat_9axis = m_quat_output;
        m_quat_gaming_rv = m_quat_9axis;
 
-       m_orientation = quat2euler(quat_output);
-
        m_rot_matrix = quat2rot_mat(m_quat_driv);
 
-       quat_error = m_quat_aid * m_quat_driv;
-
-       euler_error = (quat2euler(quat_error)).m_ang / (TYPE) PI;
-
-       m_gyro_bias = euler_error.m_ang * (TYPE) PI;
-
-       quaternion<TYPE> quat_eu_er(1, euler_error.m_ang.m_vec[0], euler_error.m_ang.m_vec[1],
-                       euler_error.m_ang.m_vec[2]);
+       quaternion<TYPE> quat_eu_er(1, m_euler_error.m_ang.m_vec[0], m_euler_error.m_ang.m_vec[1],
+                       m_euler_error.m_ang.m_vec[2]);
 
        m_quat_driv = (m_quat_driv * quat_eu_er) * (TYPE) PI;
        m_quat_driv.quat_normalize();
 
        if (is_initialized(m_state_new))
        {
-               m_state_error.m_vec[0] = euler_error.m_ang.m_vec[0];
-               m_state_error.m_vec[1] = euler_error.m_ang.m_vec[1];
-               m_state_error.m_vec[2] = euler_error.m_ang.m_vec[2];
+               m_state_error.m_vec[0] = m_euler_error.m_ang.m_vec[0];
+               m_state_error.m_vec[1] = m_euler_error.m_ang.m_vec[1];
+               m_state_error.m_vec[2] = m_euler_error.m_ang.m_vec[2];
                m_state_error.m_vec[3] = m_state_new.m_vec[3];
                m_state_error.m_vec[4] = m_state_new.m_vec[4];
                m_state_error.m_vec[5] = m_state_new.m_vec[5];
@@ -256,8 +259,6 @@ inline void orientation_filter<TYPE>::time_update()
 template <typename TYPE>
 inline void orientation_filter<TYPE>::time_update_gaming_rv()
 {
-       quaternion<TYPE> quat_diff, quat_error, quat_output;
-       euler_angles<TYPE> euler_error;
        euler_angles<TYPE> orientation;
        euler_angles<TYPE> euler_aid;
        euler_angles<TYPE> euler_driv;
@@ -281,29 +282,8 @@ inline void orientation_filter<TYPE>::time_update_gaming_rv()
 
        m_pred_cov = (m_tran_mat * m_pred_cov * tran(m_tran_mat)) + m_driv_cov;
 
-       if(!is_initialized(m_quat_driv.m_quat))
-               m_quat_driv = m_quat_aid;
-
-       quaternion<TYPE> quat_rot_inc(0, m_gyro.m_data.m_vec[0], m_gyro.m_data.m_vec[1],
-                       m_gyro.m_data.m_vec[2]);
-
-       quat_diff = (m_quat_driv * quat_rot_inc) * (TYPE) 0.5;
-
-       m_quat_driv = m_quat_driv + (quat_diff * (TYPE) m_gyro_dt * (TYPE) PI);
-       m_quat_driv.quat_normalize();
-
-       quat_output = phase_correction(m_quat_driv, m_quat_aid);
-
-       m_orientation = quat2euler(quat_output);
-
-       quat_error = m_quat_aid * m_quat_driv;
-
-       euler_error = (quat2euler(quat_error)).m_ang / (TYPE) PI;
-
-       m_gyro_bias = euler_error.m_ang * (TYPE) PI;
-
        euler_aid = quat2euler(m_quat_aid);
-       euler_driv = quat2euler(quat_output);
+       euler_driv = quat2euler(m_quat_output);
 
        euler_angles<TYPE> euler_gaming_rv(euler_aid.m_ang.m_vec[0], euler_aid.m_ang.m_vec[1],
                        euler_driv.m_ang.m_vec[2]);
@@ -311,9 +291,9 @@ inline void orientation_filter<TYPE>::time_update_gaming_rv()
        m_quat_gaming_rv = euler2quat(euler_gaming_rv);
 
        if (is_initialized(m_state_new)) {
-               m_state_error.m_vec[0] = euler_error.m_ang.m_vec[0];
-               m_state_error.m_vec[1] = euler_error.m_ang.m_vec[1];
-               m_state_error.m_vec[2] = euler_error.m_ang.m_vec[2];
+               m_state_error.m_vec[0] = m_euler_error.m_ang.m_vec[0];
+               m_state_error.m_vec[1] = m_euler_error.m_ang.m_vec[1];
+               m_state_error.m_vec[2] = m_euler_error.m_ang.m_vec[2];
                m_state_error.m_vec[3] = m_state_new.m_vec[3];
                m_state_error.m_vec[4] = m_state_new.m_vec[4];
                m_state_error.m_vec[5] = m_state_new.m_vec[5];

diff --git a/src/sensor_fusion/orientation_filter.h b/src/sensor_fusion/orientation_filter.h
index 892c87c..3133f8b 100644 (file)
--- a/src/sensor_fusion/orientation_filter.h
+++ b/src/sensor_fusion/orientation_filter.h
@@ -66,6 +66,8 @@ public:
        quaternion<TYPE> m_quat_9axis;
        quaternion<TYPE> m_quat_gaming_rv;
        quaternion<TYPE> m_quaternion;
+       quaternion<TYPE>  m_quat_output;
+       euler_angles<TYPE> m_euler_error;
        TYPE m_gyro_dt;
 
        int m_magnetic_alignment_factor;