Robust Inertial-Astronomic Attitude Determination Algorithm with Adaptive Star Geometrical Error Model for HCVs

摘要

Inertial/astronomic integration is an effective way to improve the accuracy of attitude determination of hypersonic cruise vehicles (HCVs). Compared with common low-dynamic aircraft, the environmental affection during hypersonic flight leads to the non-Gaussian noise character of astronomic observation. Meanwhile, rapid star geometry changing during HCVs' rapid movement causes redistribution of errors in astronomic measurements and significant variation of its main Gaussian characteristic. A kind of robust inertial/astronomic attitude determination algorithm with adaptive star geometrical error model is proposed. The adaptive star geometrical error distribution model is established for obtaining the main Gaussian model of astronomic measurement misalignment errors in flight. After that, inertial/astronomic integration model-based on misalignment errors is proposed, which avoids Euler angle transformation. On these bases, the improved robust filter algorithm is designed, which utilizes real-time astronomic error distribution as the weighting standard of Huber-based optimal estimation. Simulation results indicate that by taking the changing of main Gaussian distribution into consideration, the accuracy of inertial/astronomic integration is improved approximately 30% more than traditional algorithms adopting constant main Gaussian model in non-Gaussian HCV navigation environments.