Non-contact digital ship stern shaft rotational speed measurement device based on distributed bus

FAN Ze-yang
（China Ship Development and Design Center， Wuhan 430064， China）

Abstract： In order to solve the problems that the ship electric tachometer has large volume，poor reliability，vibration and air noise and the digital circuit type stern shaft rotational speed measuring instrument signal long distance transmission are vulnerable to interference，not individual error software compensation display terminal，the photoelectric sensing technology，distributed bus technology，microcomputer control technology，digital display technology were applied to the design and development of device for measuring ship stern shaft speed. After the analysis of the design requirements，the relationship was established between the ship stern shaft speed measurement signal acquisition，transmission，display. The photoelectric measuring method，the signals were processed by a single chip，and through the RS485 bus transmission，distributed display was established. A lot of mooring and navigation experiments in various types of ships were done. The use effect was evaluated. The results show that the device has the advantages of small volume，good real-time  performance，high reliability，strong anti-interference ability，no vibration and noise，air expansion performance，it has been successfully applied to all types of ships and the better effect is achieved.
Key words： ship； stern shaft ；rotational speed measurement； distributed bus