Method and device for rear-wheel steering of automotive vehicle
First Claim
1. A method of steering rear wheels for an automotive vehicle having a front-wheel steering system and a rear-wheel steering system, which method comprises:
- providing a first detection signal indicative of front-wheel steering force;
providing a second detection signal indicative of front-wheel steering speed;
providing a third detection signal indicative of a rear-wheel steering angle;
providing a fourth detection signal indicative of vehicle speed;
computing a rear-wheel steering angle reference value and a desired rear-wheel steering speed value based upon said first through fourth detection signals;
steering the rear wheels in accordance with said rear-wheel steering angle reference value and said desired rear-wheel steering speed value;
detecting whether there is a discrepancy between front-wheel steering force indicated by said first detection signal and front-wheel steering speed indicated by said second detection signal; and
determining an abnormality when a discrepancy is detected between said first and second detection signals;
said computing step comprising the steps of (a) computing a rear-wheel steering angle reference value from said first and fourth detection signals, (b) computing a first reference value from said second and fourth detection signals, (c) computing a second reference value from said rear-wheel steering angle reference value and said third detection signal, and (d) computing said desired rear-wheel steering speed value based upon said first reference value and said second reference value.
1 Assignment
0 Petitions
Accused Products
Abstract
In an automotive four-wheel steering system having a control unit for operating in response to various sensors associated with the front-wheel and rear-wheel steering systems to control the steering of the rear wheels. The control unit includes a first sensor for detecting front-wheel steering force or front-wheel assist (power) steering force, or cornering force occurring in the front wheels, a second sensor for detecting front-wheel steering speed, and a sensor abnormality determination device for operating, when a difference occurs between the values detected by the first sensor and the direction of the front-wheel steering speed detected by the second sensor, to indicate that an abnormality has occurred in either of the first or second sensors. Thus fail-safe operation is assured.
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Citations
6 Claims
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1. A method of steering rear wheels for an automotive vehicle having a front-wheel steering system and a rear-wheel steering system, which method comprises:
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providing a first detection signal indicative of front-wheel steering force; providing a second detection signal indicative of front-wheel steering speed; providing a third detection signal indicative of a rear-wheel steering angle; providing a fourth detection signal indicative of vehicle speed; computing a rear-wheel steering angle reference value and a desired rear-wheel steering speed value based upon said first through fourth detection signals; steering the rear wheels in accordance with said rear-wheel steering angle reference value and said desired rear-wheel steering speed value; detecting whether there is a discrepancy between front-wheel steering force indicated by said first detection signal and front-wheel steering speed indicated by said second detection signal; and determining an abnormality when a discrepancy is detected between said first and second detection signals; said computing step comprising the steps of (a) computing a rear-wheel steering angle reference value from said first and fourth detection signals, (b) computing a first reference value from said second and fourth detection signals, (c) computing a second reference value from said rear-wheel steering angle reference value and said third detection signal, and (d) computing said desired rear-wheel steering speed value based upon said first reference value and said second reference value. - View Dependent Claims (2, 3)
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4. A rear-wheel steering device for an automotive vehicle having a front-wheel steering system and a rear-wheel steering system which steers the vehicle'"'"'s rear wheels in accordance with a rear-wheel steering angle reference value and a rear-wheel steering speed value, said device comprising,
first means for detecting front-wheel steering force and generating a front-wheel steering force signal indicative thereof; -
second means for detecting front-wheel steering speed and producing a steering speed signal indicative thereof; third means for detecting a rear-wheel steering angle and providing a rear-wheel steering angle signal indicative thereof; fourth means for detecting vehicle speed and producing a vehicle speed signal indicative thereof; computing means responsive to outputs from said first through forth means for computing a rear-wheel steering angle reference value and a desired rear-wheel steering speed value for said rear-wheel steering system, and abnormality determination means for determining an occurrence of an abnormality in either said first or second means based upon a difference between a front wheel steering force signal from said first means and a front-wheel steering speed signal detected by said second means; said computing means computing (a) a rear-wheel steering angle reference value in response to front-wheel steering force and vehicle speed signals respectively transmitted from said first and fourth means, (b) a first reference value based upon front-wheel steering speed and vehicle speed signals from said second and fourth means, (c) a second reference value based upon said rear-wheel steering angle reference value and a rear wheel steering angle signal from said third means, and (d) a desired rear-wheel steering speed value for said rear-wheel steering system based upon said first and second reference values. - View Dependent Claims (5, 6)
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Specification