MEASURING APPARATUS FOR THE AUTOMATIC MEASUREMENT OF SPEED, TRAVELLED DISTANCE AND DIRECTIONAL CHANGES OF A MOVABLE BODY

摘要

A measuring apparatus for the automatic measurement of speed, travelled distance and directional changes of a movable body by means of ultrasonic wave Doppler shifts has two measuring units disposed on the underside of a vehicle at a spacing transversely of the vehicle substantially equal to the vehicle width. Each measuring unit comprises means for effecting measurements in a direction parallel to the direction of travel of the vehicle and includes a transmitter and a receiver, the transmitters being disposed such that ultrasonic beams transmitted therefrom at an angle are reflected from the ground and are received by the receivers. The Doppler shift of the received signals is used for indicating the speed and the distance travelled, and a difference between left-hand and the right-hand measured values from respective ones of the measuring units relating to the travelled distance is used to indicate the directional deviation of the vehicle relative to the ground.