Data processing: measuring – calibrating – or testing – Measurement system – Speed
Reexamination Certificate
1999-01-26
2001-05-08
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Speed
C702S145000
Reexamination Certificate
active
06230110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a wheel velocity detecting apparatus and, more particularly, to an apparatus which has improved accuracy in detecting a wheel velocity chiefly in a low velocity range by processing a signal from a rotary sensor (pickup sensor).
2. Description of the Related Art
Conventionally there is known a wheel velocity detecting apparatus for detecting a signal from an electromotive force or a frequency corresponding to the rotational speed of wheels by a pickup coil arranged near a wheel and converting the signal into a square wave to detect a wheel velocity based on an edge interval of the square wave.
For example, Japanese Patent Laid-Open Publication No. Hei 3-18756 discloses a technique for detecting a wheel velocity by generating a square wave of duty ratio 1:1 from a sensor signal to detect a wheel velocity based on an edge interval of the square wave pulse and the circumference of the wheel.
However, when a wheel velocity is detected by generating a square wave pulse from a sensor signal at a very low velocity (for example, 10 km/h or lower), an edge is not inputted in time, even at the updating timing of the wheel velocity, so that the wheel velocity has to be derived from an estimation, which causes a problem of prohibiting accurate detection of the wheel velocity.
It is naturally conceivable that a wheel velocity may be uniformly set at 0 km/h during a very low velocity, but this does not solve the problem, as a wheel velocity still fails to be accurately detected.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above described problem inherent in the prior art technique, and an object thereof is to provide a wheel velocity detecting apparatus capable of detecting a wheel velocity at high accuracy in a very low velocity range (10 km/h or lower).
In order to achieve the above mentioned object, the present invention provides a wheel velocity detecting apparatus for detecting the wheel velocity based on a signal from a rotary sensor, comprising a differentiator for time-differentiating the signal from the rotary sensor, an integrator for time-integrating the signal from the rotary sensor, a squarer for squaring the signal from the rotary sensor, a multiplier for multiplying the output from the differentiator by the output from the integrator, a subtractor for calculating the difference between the output from the squarer and the output from the multiplier, and a detector for detecting a wheel velocity based on the output from the subtractor.
The present invention is also a wheel velocity detecting apparatus for detecting a wheel velocity based on a signal from a rotary sensor, comprising a first differentiator for time-differentiating the signal from the rotary sensor, a second differentiator for time-differentiating the signal from the first differentiator, an integrator for time-integrating the signal from the first differentiator, a squarer for squaring the signal from the first differentiator, a multiplier for multiplying the output from the second differentiator by the output from the integrator, a subtractor for calculating the difference between the output from the squarer and the output from the multiplier, and a detector for detecting the wheel velocity based on the output from the subtractor.
The wheel velocity detecting apparatus according to the present invention also comprises a first differentiator for time-differentiating a signal from a rotary sensor, a second differentiator for time-differentiating the signal from the first differentiator, a squarer for squaring the signal from the first differentiator, a multiplier for multiplying the output from the second differentiator by the signal from the rotary sensor, a subtractor for calculating the difference between the output from the squarer and the output from the multiplier, and a detector for detecting a wheel velocity based on the output from the subtractor.
Advantageously, the wheel velocity detecting apparatus according to the present invention may further comprise a transformer for transforming a signal from the rotary sensor into a square-wave, a second detector for detecting a wheel velocity based on an edge interval of the square wave and the circumference of the wheel, and a compensator for compensating the wheel velocity detected by the detector based on the wheel velocity detected by the detector and the wheel velocity detected by the second detector.
REFERENCES:
patent: 3996590 (1976-12-01), Hammack
patent: 4669046 (1987-05-01), Kubo
patent: 5043658 (1991-08-01), Braschel et al.
patent: 5541859 (1996-07-01), Inoue et al.
patent: 5566094 (1996-10-01), Kojima et al.
patent: 5748503 (1998-05-01), Saeki et al.
patent: 4342868 A1 (1993-12-01), None
patent: 3-018759 (1991-01-01), None
patent: 8-281125 (1997-10-01), None
Patents Abstracts of Japan, Feb. 23, 1984 vol. 8 No. 42.
Hoff Marc S.
Kenyon & Kenyon
Raymond Edward
Toyota Jidosha & Kabushiki Kaisha
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