Unscented Kalman Filter Dealing With Star Sensor And Gyro System With Multiplicative Noise

Satellite attitude determination is an important part of satellite attitude controlsystem.The satellite attitude determination system with star-sensors and gyros is acommon combination to achieve high precision of attitude determination and it hasbeen used widely.To improve the accuracy of the star-sensors and gyros combinationsystem, scholars have done much research.However,the systems they studied are gen-erally assumed without multiplicative noise.In this paper, for the star-sensor and gyrosystem,considering the relative benchmark error’s in?uence,the measurement equa-tion with multiplicative noise and the equation of sate are established basing on errorquaternion.Then,the augmented unscented Kalman filter is discussed.Through extend-ing the dimension of the state vector,the algorithm introduce the multiplicative noise tothe sample points,making the in?uence of the multiplicative noise can be delivered andestimated in the nonlinear system in the process of state prediction and update,and sothe filtering value can be closer to the real value.The main research work are as follows:1. The relative benchmark error in the star-sensor model: firstly,the benchmarkerror of the star-sensor which is caused by vibration and other factors is analyzed,thenits form in the star-sensor measurement model is derived.2. Modeling of satellite attitude determination system: The attitude representa-tion of Euler Angle and Quaternion are analyzed and generalized.Then the attitudekinematic and dynamic models about satellite are developed employing error Quater-nion and Euler-Angle representation.For the star-sensor and gyro system,the stateequation of the system is established basing on the attitude kinematic and dynamicmodel and the gyro model.Considering the benchmark error of the star-sensor,the mea-surement equation with multiplicative noise is established.3. Algorithm of nonlinear system with multiplicative noise:For the star-sensor andgyro system,the augmented unscented Kalman filter suited to dealing with nonlinearsystem with multiplicative noise is proposed.Large number of simulations show thatcompared with UKF not dealing with multiplicative noise,this algorithm can improvethe accuracy of the attitude determination system e?ectively,and it performs well.