System and method for determining vehicle ground speed
First Claim
1. Method to determine the relative speed between a first body (A) and a second body (B) in which a plurality of sensing means (1, 2.1 . . . 2.n) are secured to one of said bodies (A) and located thereon, staggered by fixed distances in the direction of relative movement of said bodies, and responsive to a characteristic of said other body (B);
- in which sensed characteristic signals are derived from each said sensing means, said sensed signals being time-shifted with respect to each other in accordance with the distance (L) of said sensing means from each other,and comprising, in accordance with the invention, the steps ofgenerating a first sensed characteristic signal (s1) from a sensing means located at the leading portion of said one body (A);
generating a plurality of second sensed characteristic signals (s2.1 . . . 22.n) which are time shifted with respect to each other from said sensing means located at portions of said body trailing respect to said leading portion;
time-delaying said first sensed characteristic signal to obtain a delay signal (s1);
simultaneously comparing said time delayed signal (s1) with each of said generated characteristic signals (s2.1 . . . s2.n) and obtaining an output signal representative of optiimal correlation between said compaired signals;
and utilizing said correlation output signal to provide an indication representative of relative speed of said bodies (A, B).
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Abstract
A plurality of sensors are located on one of the bodies, staggered by fixed distances from each other along the direction of relative movement. The sensors are responsive to a characteristic of the other body, for example to surface characteristics of a roadway. A sensed signal, picked up by a first, or leading sensor is time delayed for a predetermined time interval, and compared with signals received from all the other sensors. Upon optimum correlation, and with known time delay and distance between sensors, the relative speed can then be indicated by determining which one of the sensors picked up the signals which matched the time delay signal. The amplitudes of the signals can be dynamically equalized and the time delay itself changed to permit output over wide ranges, or with respect to different scaling units.
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Citations
22 Claims
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1. Method to determine the relative speed between a first body (A) and a second body (B) in which a plurality of sensing means (1, 2.1 . . . 2.n) are secured to one of said bodies (A) and located thereon, staggered by fixed distances in the direction of relative movement of said bodies, and responsive to a characteristic of said other body (B);
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in which sensed characteristic signals are derived from each said sensing means, said sensed signals being time-shifted with respect to each other in accordance with the distance (L) of said sensing means from each other, and comprising, in accordance with the invention, the steps of generating a first sensed characteristic signal (s1) from a sensing means located at the leading portion of said one body (A); generating a plurality of second sensed characteristic signals (s2.1 . . . 22.n) which are time shifted with respect to each other from said sensing means located at portions of said body trailing respect to said leading portion; time-delaying said first sensed characteristic signal to obtain a delay signal (s1); simultaneously comparing said time delayed signal (s1) with each of said generated characteristic signals (s2.1 . . . s2.n) and obtaining an output signal representative of optiimal correlation between said compaired signals; and utilizing said correlation output signal to provide an indication representative of relative speed of said bodies (A, B). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 20, 21, 22)
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17. System according to claim 17, wherein said automatic rate controlling means comprises a bi-directional shift register (21) having two inputs, one of said inputs being connected to the output indicator means (14, 15, 16) representative of lowest speed, and the other input (20) to said bi-directional shift register being representative of highest speed, shifting of signals in said shift register being controlled by one or the other of said outputs to shift towards the opposite direction;
the means controlling the shift rate of the time delay shift register (9) including means (25,
26) providing a plurality of different clock rates (fo;
fo/2;
fo/4;
fo/8) to said time delay shift register, the output of said bi-directional shift register controlling which one of said clock rates being connected to said time delay shift register (9).- View Dependent Claims (18, 19)
Specification