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High-Performance Motion Control of the METIS Cold Chopper Mechanism

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Author: Huisman, R. · Paalvast, S. · Brandl, B.R. · Dool, T.C. van den · Eggens, M. · Janssen, H. · Aitink-Kroes, G. · Molster, F. · Teuwen, M. · Venema, L. · Jayawardhana, B.
Publisher: Institute of Electrical and Electronics Engineers IEEE
Source:IEEE/ASME Transactions on Mechatronics, 5, 21, 2453-2465
Identifier: 572342
Article number: 7487002
Keywords: Materials · Control synthesis · Tip/tilt mechanism · Control system analysis · Hardware · Hysteresis · Mirrors · Motion control · Optical telescopes · Reconfigurable hardware · Telescopes · Critical component · Extremely Large Telescopes · High-performance motion control · Hybrid controls · Performance requirements · Repetitive control · Repetitive controller · High Tech Systems & Materials · Industrial Innovation · Nano Technology · OM - Opto-Mechatronics · TS - Technical Sciences


We present the main results of the performance test campaign of the Mid-Infrared European Extremely Large Telescope Imager and Spectrograph (METIS) Cold Chopper Demonstrator (MCCD). This tip/tilt mirror, which operates at a temperature of 77 K, is one of the critical components in the METIS for the European Extremely Large Telescope. The performance requirements of the MCCD relate to the field of fast and very accurate reference tracking. We discuss the applicability of different high-performance motion control strategies and describe the control synthesis of a repetitive and of a novel hybrid controller. We identified the presence of nonlinearities in the plant, which limits the performance of the hybrid controller. The repetitive controller shows very promising results and can handle the nonlinearities in the system. This experimental phase concludes the MCCD program, which was initiated to verify the feasibility of a high-performance cryogenic tip/tilt mirror at an early stage in the METIS development. Because of the very promising test results, no significant changes to the hardware will be implemented. We believe that minor adjustments will suffice to meet all requirements of the final hardware after integration with the METIS instrument.