Vehicle speed detection system

摘要

Correction for compensating for errors caused by the pitching movement of a vehicle is executed with high accuracy at low cost. The ground speed of the vehicle sensed by a Doppler sensor is corrected with angular velocities with respect to the center of gravity of the vehicle. In this correction, the center of rotation of the vehicle and the rotation of the Doppler sensor itself during the pitching movement of the vehicle are taken into account. In order to mount the Doppler sensor at a high level in the vehicle without increasing the output power of the sensor, arrangement is made such that the relationship between the difference between the actual installation level of the Doppler sensor and a reference installation level and the amount of correction of beam depression angle is stored in a look-up table; the beam depression angle corresponding to the actual installation level of the Doppler sensor is calculated through correction with the corresponding correction amount of the table; and the sensed ground speed of the vehicle is corrected with the calculated beam depression angle.