Estimation and Correction of Azimuth and Attitude Errors of Attitude Tracking for Vehicular Spacecraft

Shortening the ground preparation time of vehicular spacecraft is an important topic in the aerospace field. The time is hard to be significantly shortened using the traditional methods because initial alignment and spacecraft erection must be fulfilled in order. To solve the problem, an estimation and correction method for azimuth and attitude errors of attitude tracking is proposed in this article. We propose a real-time error estimation model to reveal the effect of the initial azimuth, attitude errors, and the gyro biases of the spacecraft inertial measurement unit (SIMU) on the current azimuth and attitude errors during attitude tracking, making it possible to post-compensate the initial coarse azimuth error and the gyro biases of the SIMU at the end of attitude tracking. This model is the key and the theoretical basis of our proposed method. Detailed estimation and correction steps are designed, to achieve the purpose of fulfilling the spacecraft erection and the fine-alignment of the vehicular inertial measurement unit (VIMU) in parallel. The results of the simulations and experiments show that the preparation time is remarkably shortened using the proposed method, without decreasing the final azimuth and attitude accuracy of the SIMU. This proposed method detaches the inherent viewpoint that fine-alignment must be completed before attitude tracking and spacecraft erection in the traditional horizontal collimation scheme. It provides a completely new way to shorten the ground preparation time of vehicular spacecraft.