Attitude Measuring Method Of High Dynamic Bodies

Self-spin mode has such particular advantages as simplifying the configuration of control systems,reducing the influence of asymmetrical structure and has been widely adopted by both traditional projectiles and guided ones.However,self-spin also results in high dynamics and coning motion.The attitude measuring method of spinning high dynamic bodies is therefore investigated in this dissertation and the main conclusions are as following.Firstly,the dynamic model and transfer function for vibratory gyroscopes under high dynamic condition are derived.It is noted that the dynamic property of gyroscopes will change from a second-order system to a forth-order system.And the reason for the drifting of scaling factor of gyroscopes under coning motion is because of the complex coupling between detecting direction and sensitive direction.The nonlinear error model and dynamic model of gyroscope are then developed,and a coning motion calibration method for error coefficients in the models are proposed as well.The experiments shows that the influences of single axial rotation and dual axial rotation in the dynamic error model of gyroscope are equivalent to the nonlinear error,and the influence of triaxial rotation in the dynamic error model can be compensated by means of the coning motion calibrating method.Secondly,an optimization algorithm is also developed in detail based on the Euler attitude algorithm and the two-stage structure attitude algorithm.The dynamic coning model is deduced by rotation vector,and it proves that the classical coning model is just a special case of the dynamic coning model.The effect of dynamic coning motion on attitude algorithm is analyzed.It is observed that the attitude error is actually composed of drifting error and oscillating error,while the roll angle error may further pass to pitch angle and yaw angle and result in an additional error.It is also noted from simulation that the optimization algorithm cannot restrain the drifting error effectively because of the small angle approximation.Meanwhile,with the increase of the coning frequency and half angle,both the drifting error and the amplitude of oscillating error will increase,and the accuracy of optimization algorithm will further decrease.Thirdly,the coning model of high dynamic body is completed based on the dynamic coning model.And some new slewing algorithms are developed to overcome the drawback of the traditional slewing algorithm,which consist of the slewing algorithm and the improved slewing algorithm.And its accuracy depends on the precision of the slewing rate.Both a cone algorithm and an improved one are proposed based on the definition of the cone frame and cone attitude,which are then proved to be equivalent to the dynamic coning model and can eliminate the attitude error induced by coning motion effectively.A modification of the improved slewing algorithm for navigation is also given and the difference of the angular rate in the rotating table experiment is analyzed by it.An implementation plan for three axis rotating table to simulate angular motion under coning case is suggested as well.Fourthly,a synchronous rectification algorithm is proposed to eliminate the phase delay of angular velocity induced by measurement and signal processing.And a cone algorithms of high-frequency scheme are provided for attitude resolving and attitude matrix updating for high dynamic bodies to increase resolving frequency.The feasibilities of synchronous rectification and cone algorithms of high-frequency are verified by simulation.Meanwhile,considering the misalignment of velocity of body and the rotating axis of coning motion,an inertial measuring method is proposed to build the measuring equation and resolving equation.A geometry-solving algorithm of real coning motion is derived in detail to obtain the characteristics of coning motion.The nutation angle of the rotating axis represents the radius of large circle,and the nutation angle of spinning body represents the radius of small circle.A flight simulation of a spinning body with coning motion is designed and used to verify the measuring method and the geometry-solving algorithm.Finally,the innovative points are concluded and some valuable points for future work are forecasted.