Abstract:
Rotary encoder is an angle measuring instrument which is widely used in various instruments and machines especially in the industrial sector such as printers, CNC machines, theodolites and servo motors. At the moment, there is no accredited calibration system for rotary encoder in Thailand. The rotary encoder calibration system is developed to accredited calibration capability in Thailand. The measurement principle of a rotary encoder is based on the Equal-Division-Averaged (EDA) Method which was invented by Dr. Tsukasa Watanabe, National Institute Metrology of Japan. This thesis objective is to develop rotary encoder calibration system to have suitable performance for accurate and precise angle calibration in Thailand and to transfer measurement values to industrial and public sector. The system provides the uncertainty of measurement less than 0.2" (arc second). The system can be used in vertical and horizontal axis. With 30 kilogram weight, this calibration unit is the portable system and can be carried by one man for swapping between both axes. Moreover, the system can be self-calibrated so that there is no need to perform calibration aboard; hence this can save a lot of time and budget. This thesis will include the principle, the configuration and the operation process. The system was used to calibrate several instruments such as Rotary Encoder, Autocollimator, Polygon Mirror and Electronic Level. The measurement results show the system good performance and the EN RATIO is less than 1.