| 摘要 |
PROBLEM TO BE SOLVED: To optimize the time to warn of the possibility of a rear collision according to the degree of danger of the rear collision. SOLUTION: A seatbelt 11 is strongly pulled by a motor 16 to strongly restrain an occupant J against a seat 3, a predetermined time (e.g. 0.5 sec) before the time when a vehicle 2 behind is expected to collide against the rear of one's own vehicle 1. Before actuation of the motor 16, if a determination is made using a criterion value that there is the possibility of rear collision, a warning means 22 such as a buzzer is actuated. The criterion value can be changed. For example, characteristic curvesβ1 toβ3 shown in Figure. 3 are set, withβ1,β2 andβ3 corresponding to the assumption that the vehicle 2 decelerates at a speed equivalent to 0.8 G, 0.6 G and 0.4 G, respectively. If the relative speed V between the vehicles is high or if the distance L between the head of the occupant J and a headrest 3c is long, the degree of danger is determined to be high andβ3 is selected, and otherwise,β1, for example, is selected. A predetermined distance D calculated by checking the selected characteristic curve against the relative speed V is used as the criterion value. The warning means 22 is actuated when the actual inter-vehicle distance becomes equal to or less than the predetermined distance D.
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