Observing the results it can be seen that there exists an offset (the bias) on all of the three axes, but mostly on y (positive) and z axis (negative). To calculate angle α, the output of the gyroscope ω (angular speed), is integrated over time t [25]: !
(3-3) The graph below shows the results without compensating for the bias error introduced by the offset: during 20 seconds we get an angle of 0.12 and -0.15 radians around the y and z axis respectively. For example, the error on the y axis is: 0.12/20 = 0.006 radians/s, or 0.35 degrees/s
