Evaluation of Satellite Acceleration Determination Methods in GNSS/INS Deep Integration

Deep integration is a deep level integration of Global Navigation Satellite System (GNSS) and Inertial Navigation System (INS). One of the key steps in deep integration is to find out the motion dynamics between the receiver and satellite in line-of-sight direction and build the connection with the carrier tracking loop of the receiver. The carrier loops have high frequency of updating, while fragile to lose lock. As a result, timely and accurate satellite acceleration information is especially important in deep integration. Similar to the satellite velocity determination method, the derivative method can be applied to calculate satellite acceleration based on the second order derivative of the six orbital elements and corresponding correction terms, while the calculation formulas are relatively complex. The kinematic method and the difference method use the kinematic equations and velocity difference to solve the satellite acceleration respectively, which reduces the computation load significantly. Based solely on broadcast ephemeris, this paper implements three real-time satellite acceleration determination methods, namely derivative, kinematic, and difference method. All above methods are evaluated on calculation load, calculation accuracy, and application range with corresponding precise ephemeris as reference acceleration by Chebyshev interpolation. For the requirements of satellite acceleration determination in GNSS/INS deep integration, the method evaluation results in this paper can be used as an important reference for strategies selection under different scenarios.