Application of Fuzzy Logic and Multisensor Data Fusion Techniques to On-board GPS-based Spacecraft Navigation

Stefano Giacomini and Livio Marradi

Abstract:	Autonomous on-board spacecraft guidance and navigation can benefit from multisensor data fusion techniques both in terms of achievable accuracies in position and attitude determination, as well as in terms of increased system reliability. In particular, sign&ant benefits can be found in cases where measurement noise conditions may change during the mission and safety-critical spacecraft operations are involved. Accuracy, reliability and integrity are three of the main requirements which will be involved in autonomous spacecraft navigation and rendez-vous missions. Those requirements may be achieved by integrating, now available, space qualified GPS receivers that provide both position and attitude information with specific mission related instruments and Inertial Navigation Sensors. LABEN is currently developing a spaceborne GPS receiver for position and attitude determination. In parallel, research activities are currently in progress within the Research and Strategic Developments Dept. of LABEN in the fields of on-board autonomy and multisensor data fusion, A rendez-vous simplified study case has been taken as reference, and involves integration of the GPS receiver data with data from a Laser Range Finder and a three axis Inertial Navigation Sensor. The core of the data fusion system is based on an Extended Kalman Filter that includes an accurate gravitational dynamic model. Because sensor measurements are all affected by various error sources that are variable in time according to spacecraft-target- GPS relative positions and configurations and due to the presence of GNC rendez-vous manouvres, the Kalman filter operation needs to be adapted in real- time to obtain best performance on the basis of the current conditions. This is achieved by acting both on the filter covariance matrices and on the dynamic model itself. A novel adaptive scheme employs a Fuzzy Logic layer to control the filter performance by analyzing incoming sensors data on the basis of a set of rules. The fuzzy rule set is designed with a twofold objective: achieve better accuracy in position determination and also act as a controller on GNC and sensors operation correctness and consistency. Preliminary simulation tests of the spacecraft rendez- vous system with the Fuzzy Logic aiding have provided good results and in-sight on the validity of the adopted sensor fusion scheme, compared with the only Kalman filtering of sensors data.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	205 - 216
Cite this article:	Giacomini, Stefano, Marradi, Livio, "Application of Fuzzy Logic and Multisensor Data Fusion Techniques to On-board GPS-based Spacecraft Navigation," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 205-216.
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