| 摘要 |
PURPOSE:To measure accurately the ground speed of vehicle by detecting the relative movement of a road surface. CONSTITUTION:Plural image pick up device 3 are provided before and behind a vehicle and the detected signal being from each picture element is outputted in order as a detected signal line OS according to the density of each part of the image by inputting the image of the opposing surface. A delay circuit 5A inputs the signal line OS on each fixed motion period and outputs by delaying the prescribed number r of picture elements only. A multiplying circuit 5B inputs the signal line OS on each motion period then, multiplying in order this signal line OS and the delayed signal line OS by the circuit 5A in the motion period immediately before and the multiplied value is integrated by an integration circuit 5C. A delay control circuit 5G changes step by step the number r0 of the delayed picture elements of the circuit 5A on each motion period. An arithmetic circuit 5F then memorizes the number r0 of the delayed picture elements in the motion period when the integrated value showed the maximum value and calculates a speed V from the number r0 of picture elements. The number r0 in this case corresponds with the relative movement of the surface by the vehicle transferring and the correct ground speed V of the vehicle is calculated from the number r0 of picture elements.
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