Analysis and on-line compensation of gravity disturbance in a high-precision inertial navigation system

Zero velocity update technology (ZUPT) has frequently been used as a tool to reduce divergence when the inertial navigation system (INS) is working in pure inertial mode. In general, the normal gravity model is adopted to calculate the gravity vector, and the effect of gravity disturbance is neglected. We present a new point of view to explain the influence of gravity disturbance on INS and point out that gravity disturbance is one of the most significant error sources of the high-precision INS. Two real-time gravity disturbance compensation methods are proposed. An about 110-km-long vehicle test has been conducted in mountainous terrain with a drastic change of gravity disturbance. The test results proved the correctness of the new explanation and the feasibility of the two on-line compensation algorithms for land vehicles. With gravity disturbance compensation in conjunction with ZUPTs, the total horizontal error at the end of the test was reduced from 8.93 to 3.75 m, and the elevation error was reduced from 1.63 to 0.80 m.