OPTICAL METHOD FOR RAILWAY TRAIN SPEED DETERMINATION Russian patent published in 2014 - IPC G01P3/68 

FIELD: transport.

SUBSTANCE: recorders representing two video recorders located at specified height above railway bed simultaneously take pictures of railway bed, at each time point current frame from the first video recorder is saved in memory, frame with the same railway bed fragment is determined in video sequence from the second video recorder, shift between these frames is calculated, and from difference in serial numbers of frames and shift between them speed is found from formula $$V=F\cdot \frac{S+\Delta L}{\Delta N},$$ where F is shooting rate of video recorders (quantity of frames per second), S is shift between video recorders, ΔL is shift between frames with the same fragment of railway bed from two video recorders, ΔN is difference in frame numbers with the same fragment of railway bed from the first and second video recorders.

EFFECT: improved accuracy.

5 dwg