Hardware Implementation of Low Cost Inertial Navigation System Using Mems Inertial Sensors

Abstract

This work deals with a new approach to calibrate low cost six degree of freedom MEMS inertial Navigation system to be used in Unmanned Air Vehicle (UAV). The accelerometer and gyroscope are modeled with inter axis misalignment correction. To determine calibration parameters of a tri axis accelerometer at least nine equations will be required to solve for nine unknowns (3 scale factor, 3 zero bias, 3 misalignment angles). In this new approach three new linear equations were formulated to determine the calibration parameters thereby reducing number of positions needed in multi position test. The formulated methodology for accelerometer is validated by conducting twelve position tests. All combination of positions was attempted iteratively. After identifying the singularities, the Study on the results suggests that only six different positions of the sensors are enough to solve nine unknowns within 3 equations. Similar methodology was applied to calibrate tri axial Gyroscope in rate test. Rate test results were studied and analyzed with standard values provided my sensor manufacturer. An inertial sensor (SINS) error model is introduced based upon the calibrated data. Final algorithm is uploaded in the ATMEGA 328 micro controller which is embedded in the IMU in order to remove errors from the sensors output. Navigation algorithm is also coded to track the object in the desired frame using MALAB and Arduino software. The 3D view of the attitude and position variation of sensors in a real time plot is viewed by Python software and MATLAB.