Rule-Based Cooperative Control of Optically Linked Model Spacecraft: Experimental Study

• Published in: Journal of guidance, control, and dynamics control, and dynamics, 2004-01, Vol.27 (1), p.83-90
• Main Authors: C. Wang, P. K, Yee, J, Sayegh, E. G, Hadaegh, F. Y
• Format: Article
• Language: English
• Subjects: Accuracy; Aluminum; Applied sciences; Collectors; Computer science; control theory; systems; Control theory. Systems; Cooperative control; Electrical engineering; Exact sciences and technology; Interferometry; Laboratories; Lasers; Light; Satellites; Sensors
• ISSN: 0731-5090; 1533-3884
• DOI: 10.2514/1.9288

An experimental study is made on the alignment of an optically linked autonomous model-spacecraft triad with features similar to those in a separated-spacecraft interferometer. Each model spacecraft is magnetically levitated and free to rotate about a fixed axis. Two laser beams are used to simulate the light from a distant star impinging on the collectors of a space interferometer. The laser beams reflected from the servo-controlled mirrors on the collector model spacecraft impinge on an optical sensor array mounted on the combiner model spacecraft. Simple rule-based cooperative controls are developed for optical alignment in the presence of rotational drift induced by external impulsive or persistent disturbances. These controls are driven by events defined by the laser-beam activation of certain sensors. The resulting controlled system is a hybrid continuous-time and discrete-event system. Experimental results show that the derived control laws are effective in achieving optical alignment of the model spacecraft triad, using only a small number of optical sensors with binary outputs, provided that the relative angular drift speeds are sufficiently small.