Vehicle speedometer

摘要

The vehicle speed is calculated by a revolution counter (4) fitted to at least one wheel. This value is compared with the actual speed as determined by use of a navigation system (8), e.g. Global Positioning System, at pre-set time intervals. The comparator (11) determines a correction factor to be applied to the counter-derived speed by the computer (6) at regular intervals e.g. once daily or after programmed events such as vehicle start or excess of a given speed. In addition to display of the speed on the instrument panel (7), the corrected speed value can be transferred to other control devices in the vehicle e.g. to calculate the distance covered.