| 摘要 |
PURPOSE:To detect an accurate vehicle speed, by correcting the acceleration of a vehicle on the basis of acceleration of gravity due to the inclination of a vehicle body caused by braking of the vehicle to calculate the vehicle speed and detecting a wheel speed at a non-braking time to calculate the vehicle speed. CONSTITUTION:A CPU 31 reads the vehicle acceleration detected by an acceleration sensor 10 as acceleration data through an A/D converting input port 35 and continuously judges whether a brake is in an ON-state on the basis of a flag value reflecting the state of a brake switch 15. At a non-braking time, a vehicle speed is operated from the outputs of the number-of-rotation sensors 3, 7 of left and right wheels 1, 5. At a braking time, since the component of acceleration of gravity due to nose diving forwardly inclining a vehicle is together detected by the sensor, the inclination of the vehicle is corrected. The acceleration data after correction is integrated to be added to the vehicle speed immediately before the starting of braking. By this method, an accurate vehicle speed can be detected not only at a non-braking time but also at a braking time.
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