Research Of Spacecraft Autonomous Navigation Algorithm And Its DSP Realization Based On Small Sample Data

Under the requirement of multi-maneuver flight mission, spacecraft sometimes has to perform autonomous navigation by using on-board sensors in a short time. Celestial navigation has many advantages in this field because of its completely autonomous ability and high resulted navigation accuracy. The autonomous celestial navigation algorithm in the case of small sample observation is investigated in this paper. The orientation information of the sun, the moon and the earth, together with ephemeris are utilized to develop autonomous navigation algorithm, as well as its realization by DSP hardware.Taking account of the perturbation of the earth's shape, the gravitation of the sun and the moon, the radiation pressure from the sun light and atmosphere drag, a precise orbital dynamic model of spacecraft is established in the equatorial geocentric inertial coordinate system (J2000). In the stage of the sun and the moon in sight, azimuth of the sun, the earth and the moon in the spacecraft body coordinate system is simulated. Combining the simulated azimuth with the ephemeris of the sun and the moon, the state equation and observation equation are modeled. The initial orbital parameters calculated by least square method are used in orbit state equation to predict spacecraft state and to realize autonomous navigation.Different sampling periods of sensors and the recursive steps of initial states are investigated. The navigation precision with different condition such as different precision of sensors, different length of observation time are compared. Then, three orbit types, consisting of low-altitude orbit, middle-altitude orbit and high-altitude orbit, are simulated respectively. According to comparison between the calculated results, conclusions are summarized as follows: the accuracy of sensors and length of the observation time have great influence to the navigation precision in different orbit types. When navigation accuracy is highly expected, the sensor with higher accuracy should be chosen and the observation time should be longer, especially in high-altitude orbit.A high-speed microprocessor DSP which is specially used in digital signal process is introduced to implement the autonomous navigation algorithm, the...