| 摘要 |
PURPOSE:To eliminate a cumulative error, by calculating a representative value from a speed difference range to which the speed difference between the reference car speed at a sampling time and a detected car speed belongs and calculating he reference speed at the sampling time by adding the representative value at this sampling time to the reference speed at the previous sampling time. CONSTITUTION:A microcomputer (MC)2 takes-in the detected car speed of a car speed detector 4 at every 0.5sec when an ignition switch 10 is not in an OFF state and the memory capacity of an IC card 8 is not full to perform the sampling of the detected car speed V. Thereafter, the MC2 performs differential operational processing to calculate the speed difference A between the car speed V of this time and a reference car speed V0. Then, it is calculated which ranges, preliminarily divided into plural ones so as to provide definite speed difference from the speed difference A, the speed difference A belongs to and a predetermined representative value U is calculated on the basis of he range to which the speed difference A belongs. The value obtained by successively adding the representative value U to the previous car speed V0 is set to the reference car speed at a sampling time. By this method, the transition of a car speed can be recorded without generating a cumulative error.
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