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18 September 1997 Selection of a tape encoding system for the main axis of the Gemini telescopes
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This paper describes the selection process for the encoding system of the main (azimuth and elevation) axes of the Gemini 8-m telescopes. The main part of this is the description and results of lab tests carried out on competing systems. Two tape encoder solutions existed, one based on an inductive tape and one based on an optical tape, but neither met all the requirements. The optical system provided the better error performance, but its robustness was questionable and it was difficult to interface to the rest of the Gemini servo hardware. The inductive system was already proven to be robust and provided a standard quadrature encoder output. However, the system didn't meet some of the performance requirements and was not supplied as a complete system. The lab tests were carried out to try and resolve some of these problems and to help arrive at a decision between the two systems. The results showed that the error performance of both systems, in the presence of compensation, was good enough for the telescope application. The final decision was based upon a formal tender exercise that compared many properties of each system.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John D. Wilkes and Martin Fisher "Selection of a tape encoding system for the main axis of the Gemini telescopes", Proc. SPIE 3112, Telescope Control Systems II, (18 September 1997); doi: 10.1117/12.278836;


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