Straightness Measurement for Long-length Rails of Bridge Crane

A precision method and a device of measuring parameters of long-length crane rails, which could work continuously and automatically with real-time and online analysis, are presented in this paper. A collimated laser beam is used as a criterion of a straight line, a carriage carrying light spot position detector runs on rail, then the detector obtains parameters of the rail according to the spot position. The spot position detector consists mainly of a receiving screen, optical imaging system and a two-dimensional PSD (Position Sensitive Device). The measurement principle, the data processing method and the control system are elaborated in detail. The precision analysis proved the feasibility with total error of 0.5mm along coordinate axis, showing that the method and the device can fully meet the requirements of measuring long-length rails.