Improved Multi-Position Calibration Method for Mechanical Inertia Measurement Units

Inertial Navigation System (INS) is used in a variety of applications such as missile and marine navigation. INS is comprised of an inertial measuring unit (IMU) and a processor unit that performs the navigation mathematics calculations. In order to get accurate navigation data via INS, calibration of IMU sensors are necessary. Mechanical sensors are used in high-precision navigation, such as strategic missiles and are characterized by their low random noise. However, deterministic errors can cause very significant errors in positioning such as biases, scale factors, non-orthogonality errors, and g-sensitive and non-g-sensitive drifts. Therefore, determining an effective and accurate method of calibration is necessary to estimate and compensate for these errors. The suggested methodology accurately calculates the calibration parameters to minimize those errors. The traditional calibration techniques of the accelerometer are restricted in precision, since the estimation of scale factor and bias obtained from a limited number of positions depending on the gravity direction. These calibration techniques are also limited in the estimation of g-sensitive and non-g-sensitive drifts impacting gyro performance. This paper presents a new technique of calibration that overcomes these drawbacks, based on an enhancement of multi-position technique. Experimental results for the proposed technique was carried out to confirm its efficiency.