From ecde90333a1ea21280753978b2b08fb46975f20f Mon Sep 17 00:00:00 2001
From: Ramasamy
The accelerometer and magnetometer data are normalized based on equations (3) +
The accelerometer and magnetometer data are normalized based on equations (3) and (4) to obtain the calibrated accelerometer data (Ax, Ay, Az) and magnetometer -data (Mx, My, Mz).
+data (Mx, My, Mz).The measurement update system is used to determine the bias value that would be +deducted from the Gyroscope values (6). The equations (31), (32) and (33) are used to +compute the Kalman gain K, aposteriori state error computation Δx+(i) and +aposteriori prediction covariance P+, as shown in [4]. In equation (33), I denotes the +identity matrix H denotes the measurement matrix (identity matrix is used here) and the +apriori prediction covariance estimate P- (33).
The bias compensation (Bx, By, Bz) obtained from Δx+(i) is used for removing +dynamic bias from the calibrated gyroscope values as shown in (6). The corrected +orientation that is determined using the above sensor fusion method, is obtained from +(22) by using the conversion function quat2euler [9] as shown in (34). This estimated +orientation is used in Section 3 to compute Gravity virtual sensor data.
+When the device tilt values (pitch,roll) are changed from (0,0) to (0,Π/2), phone is rotated around x-axis, the y-axis gets aligned to earth's gravitational field -after rotation instead of the z-axis. When this rotation is applied to the equations +after rotation instead of the z-axis. When this rotation is applied to the equations given above, the values (GRx,GRy,GRz) are converted from (0,0,G) to (0,G,0) due to the shift in the axis which experiences the gravitational field (G is measure of Earth's gravity).
-- 2.7.4 From b560d96dcf4f5a1217c295cb809ed279af737786 Mon Sep 17 00:00:00 2001 From: RamasamyWhen the device tilt values (pitch,roll) are changed from (0,0) to (0,Π/2), -phone is rotated around x-axis, the y-axis gets aligned to earth's gravitational field +phone is rotated around y-axis, the x-axis gets aligned to earth's gravitational field after rotation instead of the z-axis. When this rotation is applied to the equations -given above, the values (GRx,GRy,GRz) are converted from (0,0,G) to (0,G,0) due to the +given above, the values (GRx,GRy,GRz) are converted from (0,0,G) to (G,0,0) due to the shift in the axis which experiences the gravitational field (G is measure of Earth's gravity).
Linear Acceleration virtual sensor data provides the measure of the acceleration of -a device after removing the Gravity components on the 3-axes. Accurate linear -acceleration data are calculated by subtracting gravity components from the 3-axes -calibrated accelerometer data.
+Accurate linear acceleration data are calculated by subtracting gravity components +from the 3-axes calibrated accelerometer data as shown in (38), (39) and (40). As shown +in (38) the rotation of the device on y-axis (GRy) reflects on the accelerometer x-axis +sensor data (Ax). The linear acceleration measurement on x-axis (LAx) directly +corresponds to the accelerometer x-axis sensor data (Ax) meaning linear motion along +x-axis is directly measured on the accelerometer x-axis.
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+[1] Gebre-Egziabher, H., Rhayward, R. C. & Powell, J. D. Design of Multi-Sensor +Attitude Determination Systems. IEEE Transactions on AESS, 40(2), 627 - 649 (2004)
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