| 摘要 |
PROBLEM TO BE SOLVED: To efficiently separate a background such as road surface and an object such as vehicle by specifying the background such as road surface inside a measuring area. SOLUTION: A road surface detecting part 2 detects an area having no level change in a signal outputted from a sensor 2 as road surface or stationary object such as stopped vehicle and when the stationary object is recognized, the histogram of a signal level registered for every preset road surface detecting time is prepared by sampling and registering the output signal of the sensor 2. Then, the center of gravity of the prepared histogram is operated, the signal level corresponding to the calculated center of gravity of the histogram is sampled as road surface level, and a standard deviation in the distribution of sampled road surface levels is operated and defined as the threshold value of the road surface level.
|
