Using least square to change 4 gyros system to 3 virtual gyros system, then use extend kalman filter (EKF) to fuse the data of virtual gyros system and star sensor.

• 数据处理时，利用最小二乘法将四陀螺测量系统构建为一个虚拟三轴正交陀螺，再将虚拟陀螺与星敏感器组成卡尔曼滤波器；