Determination of satallite autonomous orbit based on star light and geomagnetic field

An autonomous navigation method suitable for low orbit satellites is proposed. Different from traditional method that takes a start light angle as the observed variable, the method determines the real time orbital parameters by a start sensor and a geomagnetism sensor, and converses the unit vector observation equation of satellite position into linear equations by converting the observation data from the start sensor appropriately. With fitting the relationship of magnetic field strength and orbit height, it obtains the geocentric distance by using a magnetometer. Moreover, it determines the satellite initial orbit by Lagrange difference algorithm to provide initial value for the filter. As the performance of the filter is effected by the system model error caused from the first-order linear approximation of two body dynamic orbit model, and the high order derivative function values can be replaced by a linear combination of one order derivative function values, this paper processes the state equation by a higher order linearity in design of the KALMAN filter to reduce the calculation. By proposed method, the discretized accuracy of state equation for the filter is improved greatly. Finally, a simulation experiment is performed, which verifies that the method is effective and feasible.