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提出了一种利用陀螺与星敏感器进行组合定姿的方案。为了避免状态及量测向量选取不当而造成的误差,首先采用四元数法对卫星的姿态进行描述;接着分析了陀螺与星敏感器系统的误差源,选取误差四元数及陀螺的系统误差作为组合系统的状态,获得了系统状态方程;同时采用星敏感器的量测作为系统量测,并利用新的数学变换构得到更为准确的量测方程;最后利用扩展卡尔曼滤波,设计出了基于陀螺/星敏感器姿态确定算法。仿真结果表明该算法能有效补偿陀螺漂移带来的误差,即使采用中等精度的陀螺组件也具有较高的估计精度,同时也验证了星敏感器的量测噪声等因素对定姿精度的影响。
A scheme of combined attitude determination using gyro and star sensor is proposed. In order to avoid the error caused by the improper selection of state and measurement vector, the quaternion method is firstly used to describe the attitude of the satellite. Then the error sources of gyro and star sensor system, the quaternion of error and the system error of the gyro are analyzed. As the state of the combined system, the system state equation is obtained. At the same time, the star sensor measurement is used as the system measurement, and a more accurate measurement equation is obtained by using the new mathematical transformation. Finally, by using extended Kalman filter, Algorithm of attitude determination based on gyro / star sensor. The simulation results show that the proposed algorithm can effectively compensate for the error caused by gyro drifting. Even the gyro with medium precision has higher estimation accuracy, and also verifies the influence of star noise such as measurement noise on attitude accuracy.