Control method and device for steering the rear wheel of a vehicle
First Claim
1. A method for controlling the steering of the rear wheels of a vehicle, comprising the steps of:
- (a) determining a reference steering amount of the rear wheels in accordance with a steering condition of the front wheels when the vehicle makes a turn;
(b) correcting said reference steering amount in accordance with a condition of a road surface on which the vehicle is traveling to determine a rear-wheel steering amount;
(c) steering the rear wheels according to said rear-wheel steering amount;
said step (b) including the steps of;
(d) establishing in advance a plurality of fuzzy rules, which include a friction coefficient and a gradient of a driving road as fuzzy variables;
(e) calculating a plurality of first and second levels of contribution of a traveling condition, which is represented by detected values of said friction coefficient and said gradient for the surface of the driving road, to each of said plurality of fuzzy rules;
(f) determining at least one correction amount based on correction values, which are respectively set in said fuzzy rules in a manner that each of said fuzzy rules includes at least one corresponding correction value, and said first and second levels of contribution to each of the respective fuzzy rules; and
(g) correcting said reference steering amount in accordance with the at least one correction amount.
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Accused Products
Abstract
Various steering coefficients (KB, KC, KG) are decided in accordance with a detected car speed (V), while a correction amount (X) and a correction factor (Y) are determined by fuzzy reasoning in accordance with a detected road surface friction coefficient (μ), road surface gradient (α), and lateral acceleration (G). A reference in-phase steering amount (δRB), equal to a product of a reference in-phase steering coefficient (KB) and a detected steering wheel angle (θH), is corrected by an in-phase correction steering amount (δRC), which is equal to a product of an in-phase steering coefficient (KC) and the detected steering wheel angle (θH), with a delay determined by a time constant (T) calculated from the correction amount (X), to thereby determine a corrected in-phase steering amount (δR). A corrected anti-phase steering amount (δG), obtained by multiplying a reference anti-phase steering amount (δGB), equal to a product of the anti-phase correction coefficient (KG) and a detected steering wheel angular velocity (θHA), by the correction factor (Y), is added to the corrected in-phase steering amount (δR), to thereby obtain a rear-wheel steering amount (δ) on which the rear wheels are so steered as to match the road surface friction coefficient, road surface gradient, and lateral acceleration.
18 Citations
26 Claims
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1. A method for controlling the steering of the rear wheels of a vehicle, comprising the steps of:
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(a) determining a reference steering amount of the rear wheels in accordance with a steering condition of the front wheels when the vehicle makes a turn; (b) correcting said reference steering amount in accordance with a condition of a road surface on which the vehicle is traveling to determine a rear-wheel steering amount; (c) steering the rear wheels according to said rear-wheel steering amount; said step (b) including the steps of; (d) establishing in advance a plurality of fuzzy rules, which include a friction coefficient and a gradient of a driving road as fuzzy variables; (e) calculating a plurality of first and second levels of contribution of a traveling condition, which is represented by detected values of said friction coefficient and said gradient for the surface of the driving road, to each of said plurality of fuzzy rules; (f) determining at least one correction amount based on correction values, which are respectively set in said fuzzy rules in a manner that each of said fuzzy rules includes at least one corresponding correction value, and said first and second levels of contribution to each of the respective fuzzy rules; and (g) correcting said reference steering amount in accordance with the at least one correction amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A device for controlling the steering of the rear wheels of a vehicle, comprising:
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determining means for determining a reference steering amount of the rear wheels in accordance with a steering condition of the front wheels when the vehicle makes a turn; correcting means for correcting said reference steering amount in accordance with a condition of a road surface on which the vehicle is traveling to determine a rear-wheel steering amount; steering means for steering the rear wheels according to said rear-wheel steering amount; and fuzzy reasoning means for establishing in advance a plurality of fuzzy rules, which include a friction coefficient and a gradient of a driving road as fuzzy variables, calculating a plurality of first and second levels of contribution of a traveling condition, which is represented by detected values of said friction coefficient and said gradient for the surface of the driving road to each of said plurality of fuzzy rules, and determining at least one correction amount based on correction values which are respectively set in said fuzzy rules in a manner that each of said fuzzy rules includes at least one corresponding correction value and said first and second levels of contribution to each of the respective fuzzy rules, said correcting means correcting said reference steering amount in accordance with the at least one correction amount.
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Specification