Abstract: Aiming at the measurement efficiency issue caused by the limitations of rail structure characteristics,rail length,assembly position,and other conditions in straightness measurement during the assembly of aerospace model rails,a laser PSD（Position Sensitive Detector）based on rail straightness measurement method was studied.An automated measurement system consisting of PSD receiver,distance module,signal processing unit,and motion unit was designed,and the measurement accuracy of the system was verified,using a laser tracker standard.The measurement accuracy is better than ±0.1 mm,and the measurement efficiency is increased by 5 times.After software and hardware compatibility modification,it can also be used for measuring the spatial straightness,width,and other dimensions of various large guide rails.

Key words: PSD, Guide rail, Straightness