Adaptive-randomised self-calibration of electro-mechanical shutters for space imaging

This work describes the self-calibration of a high-precision open-loop mechanism. The self-calibration method is applied to a mechanical shutter for space applications, which was launched onboard the ESA-ROSETTA mission (launch: 2 March 2004). It is based on an adaptive ‘model reference’ and a ‘randomised’ search method which may be generalised to applications in which high performance and functionality are strongly interconnected. The method makes use of an adaptive ‘model-reference’ control approach [K.J. Astrom, B. Wittenmark, On self-tuning regulators Automatica 9 (1973) 185–199 [16]; K.J. Astrom, Theory and application of adaptive control, in: Proceedings of the Eighth IFAC World Conference, Kyoto, Japan, 1981 [17]; D.E. Seborg, S.L. Shah, T.F. Edgar, Adaptive control strategies for process control, AIChE Journal 6(32) (1986) 881–895 [18]] to guarantee mechanism performance. The proposed control system comprises both a deterministic adaptive part and a random-search one [K.L. Clarkson, Applications of random sampling in computational geometry, II, in: Proceedings of the Fourth Annual ACM Symposium on Computational Geometry, 1998, pp. 1–11 [19]; P.K. Agarwal, M. Sharir, Efficient randomised algorithms for some geometric optimisation problems, Discrete Computational Geometry 16 (1996) 317–337 [15]] to guarantee shutter mechanism functionality and performance over testing lifetime (5×104 cycles).