US 5,301,130 A · Absoulte velocity sensor

Abstract

A system and method for determining the speed of a vehicle independent of angular wheel rotation rates is provided. The system generates time-varying signals corresponding to the vertical acceleration of the front and rear wheels. The front and rear wheel signals include corresponding perturbations caused by the wheels crossing road disturbances such as bumps. A time lag occurs between perturbations in the rear wheel signal and corresponding perturbations in the front wheel signal. An adaptive algorithm correlates the signals for various time delay values until a time delay value is determined which maximizes the correlation between the two signals. The calculated time delay value corresponds to the actual time lag between the front and rear wheels occurring before the rear wheels encounter a road disturbance previously encountered by the front wheels. Thus, the invention provides a determination of the actual speed of the vehicle determined independently from the angular rotation rates of the wheels.

Claims9

Dependent claims

A system for measuring the speed of a vehicle, the system comprising:

means for sensing vertical acceleration of a front portion of the vehicle as a function of time;
means for sensing vertical acceleration of a rear portion of the vehicle as a function of time;
comparison means for comparing the vertical acceleration of the front portion and the vertical acceleration of the rear portion to determine a time lag between perturbations in the acceleration of the front portion and the rear portion caused by front and rear wheels of the vehicle successively crossing road disturbances;
and
means for calculating a true vehicle speed from the time delay and from the length of the wheel base of the vehicle.

2 more elements

A system for measuring the speed of a vehicle, the system comprising:

means for measuring vertical acceleration of a front wheel;
means for generating a time-varying reference signal corresponding to the vertical acceleration of the front wheel, the reference signal including perturbations caused by the front wheel crossing road disturbances;
means for measuring vertical acceleration of a rear wheel;
means for generating a comparison signal corresponding to the vertical acceleration of the rear wheel, the comparison signal including perturbations caused by the rear wheel crossing the same road disturbances, the perturbations of the comparison signal being delayed by a time lag from the perturbations of the reference signal, the time lag being a function of the speed of the vehicle and of the wheel base of the vehicle;
comparison means for comparing the reference signal and the comparison signal to determine the time lag between corresponding perturbations in the reference signal and the comparison signal;
and
means for calculating a true vehicle speed from the wheel base of the vehicle and the time lag.

4 more elements

Dependencies are inferred from the claim text.

Absoulte velocity sensor

Life of this patent

Absoulte velocity sensor

Life of this patent

Abstract

Claims9