Inertial Measurement Unit using multigain accelerometer sensor and gyroscope sensor

The employment of Inertial Measurement Unit (IMU) to measure the acceleration and angular rate in three axes is an important part of the navigation control system. The motion of an object (e.g. a rocket) has very wide range of acceleration at the forward axis. To obtain optimum sensitivities of all sensors, multigain accelerometer sensors should be looked into. For this a three axes accelerometer sensor (MMA7260Q) and three angular rate sensor (ADXRS150) on the three axes. Before each analog signal from sensor is imported into ADC, it should be filtered by low pass analog filter. We use a rolling average for each low pass filter, discrimination window, movement end check, and integration process to get the angle from gyroscope sensor signal and position from accelerometer sensor signal. Therefore, it is necessary to obtain the optimum of measurement. In this paper, we propose an algorithm to select the accelerometer sensor with multigain. The results show that the error averages of estimated distances in x-axis, y-axis, and z-axis are respectively 1.64%, 1.37%, and 2.73%. The error averages of the estimated angles on clockwise rotation of three axes are 0.49%, 0.77%, and 0.38% respectively, whereas for counter clockwise rotations of three axes are respectively 0.40%, 0.60%, and 0.36%.