| 摘要 |
<p>PROBLEM TO BE SOLVED: To set a threshold on the level of a received electric signal corresponding to an outgoing angle of a laser beam. SOLUTION: When a running state determination part 32 determines that the running state of a vehicle is a stable state, a distance calculation part 33 calculates the distance from an outgoing means 1 to the road surface based on time data of a reflected wave determined to be effective as a reflected wave from the road surface, and an outgoing angle calculation part 34 calculates the present outgoing angle of the laser beam based on the distance. A threshold setting means 4 sets the threshold for determining to be a received reflected wave or not on reference to a threshold table 52 based on the outgoing angle.</p> |
