A Research On High Precision Attitude Measure Technology Based On Astronomical Observation

Whether modern measure-control equipment and weapons systems could work normally relies on the information of the carrier's attitude, and high-precision attitude measurement is a technology which ensures that measure-control equipment and weapon systems perform accurately. Attitude information on large ships is usually provided by the inertial attitude measurement system, but the inertial sensors' error will lead to precision drift, so it is necessary to establish a high-precision attitude reference for the attitude measurement system's calibration and accuracy evaluation. The attitude measurement technology is studied using the photogrammetric principle. The main work of this dissertation is as follows:1. An attitude measurement method based on astronomical observations is proposed, and the stars'observation model is established using photogrammetric principle. The principles of the attitude determination algorithm and the key technologies involved are described in detail. The attitude angles error with respect to the world coordinates calculation error and image plane coordinates error of the stars is studied by the means of simulation in order to seek ways to improve the attitude accuracy.2. The theories of star apparent place calculation and astronomical refraction are studied in order to get the stars'accurate observation place. The principle and algorithm of calculating stars'apparent place is presented in detail and programmed. The program can obtain access to superior arc second accuracy. The atmospheric model and atmospheric refraction calculation algorithm, which are the two key problems of atmospheric refraction, are discussed. The accuracy of different methods is analyzed by simulation.The stars'image plane coordinates can be extracted by the use of digital image sub-pixel location technology. Star-point location algorithm is designed according to the characteristics of the star-points'gray scale distribution, and the star-point location accuracy is analyzed by the means of experiments.3. It is quite necessary to calibrate the parameters of the camera accurately in order to realize high precision photogrammetric measurement. A camera calibration method based on astronomical observations is presented based on astronomical observation to solve the problem that the traditional calibration methods can only work effectively in a limited distance. The principles and procedure of the algorithm are dwelled on. The experimental results indicate that the calibration method can achieve a good precision without the aid of precise and complex equipment, and the method performs also well when the noise exists at the same time.4. The attitude measurement system is established and experiments are designed so as to test the system's repeatability precision. Experimental results indicate that the obtained repeatability accuracy of yaw angle is better than 4″and that of pitch angle is better than 7″, proving the correctness of the theory and the feasibility of the method.