Attitude-updating Algorithm Based On A Slewing Frame

Strap-down inertial navigation system adopts advanced inertial navigation technology,and its wild application is a development trend of inertial navigation for some time to come.The inertial sensor of strap-down inertial navigation system connects with the vehicle directly,therefore,the movement of vehicle will have great influence on the output of inertial sensor and cause noncommutativities,which is called coning error in attitude-updating algorithm.As a result,it may affect the precision of strap-down inertial navigation system.To reduce the error,various attitude-updating algorithm should be designed.The thesis introduces the common coordinate system and basic working principles of strap-down inertial navigation system first,and then,researches four classic attitude-updating algorithms including Euler algorithm,direction cosine algorithm,quaternion algorithm and rotating vector algorithm.Also,it studies the radical process of updating and calculating for strap-down inertial navigation system,analyzes the error from the process and emphasizes on researching Runge-Kutta algorithm of quaternions and the four subsample algorithm of equivalent rotating vector's error under the conic motion,which is quantitative analyzed as well.On the basis of classic algorithm research,the thesis studies on a new attitude-updating algorithm based on rotating coordinate system.By using this neoteric way,attitude algorithm without error could be achieved under conic motion in theory.And a synchronous rotation coordinate system will be introduced among this way,which has the same motion of slew rate compared with motion of angular rate.Also,the factors of attitude updating and calculating without any error based on slewing frame under pure coining motion with time varying coning frequency are derived.In order to research error of this algorithm more broadly,the thesis makes an analysis of its applicability under other conditions including benign dynamic condition and generalized vibration condition.At last,it makes a simulation comparison between the algorithm based on rotating coordinate system and classic algorithm and verifies the possibilities of the new algorithm without error.