Four wheel steering system and method for trailering
First Claim
1. An all-wheel steering system for a vehicle, the steering system comprising a controller having a first input for receiving a signal from a hand wheel position sensor and a second input for receiving a signal from a vehicle speed sensor, said controller generating an output for controlling a rear wheel steering actuator, said output varying as a function of said first input, said second input, wherein, when said steering system is in a trailering mode, said output generates a rear wheel steering amount according to the formula:
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where;
R=rear wheel steer amount, F=front wheel steer amount, u=vehicle Speed (m/s), Df=front cornering compliance (deg/gravity), Dr=rear cornering compliance (deg/gravity), Nf=front cornering compliance modifier (Equal to 1 in Absence of Trailer), Nr=rear cornering compliance modifier (Equal to 1 in Absence of Trailer), a=longitudinal distance from tow vehicle front axle to center of gravity (m), b=longitudinal distance from tow vehicle rear Axle to center of gravity (m), l=tow-vehicle wheelbase (m), e=longitudinal distance from tow vehicle rear axle to trailer coupling (m), c=longitudinal distance from trailer coupling to trailer center of gravity (m), d=longitudinal distance from trailer center of gravity to trailer axle (m), G=gravitational constant (9.81 m/s2/g) Mtv=total mass of tow vehicle (kg), and Mt=total mass of trailer (kg).
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Accused Products
Abstract
An all wheel steering system for a vehicle comprising a controller having a first input for receiving a signal from a hand wheel position sensor, a second input for receiving a signal from a vehicle speed sensor, and a third input for receiving a signal that varies depending upon whether a trailer is hitched the vehicle. The controller generates an output for controlling a rear wheel steering actuator. The output varies as a function of the first, second, and third inputs such that when a trailer is hitched to the vehicle the out-of-phase rear steer amount at low speeds is reduced and the in-phase rear steering amount at high speeds is increased.
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Citations
6 Claims
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1. An all-wheel steering system for a vehicle, the steering system comprising a controller having a first input for receiving a signal from a hand wheel position sensor and a second input for receiving a signal from a vehicle speed sensor, said controller generating an output for controlling a rear wheel steering actuator, said output varying as a function of said first input, said second input, wherein, when said steering system is in a trailering mode, said output generates a rear wheel steering amount according to the formula:
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where;
R=rear wheel steer amount, F=front wheel steer amount, u=vehicle Speed (m/s), Df=front cornering compliance (deg/gravity), Dr=rear cornering compliance (deg/gravity), Nf=front cornering compliance modifier (Equal to 1 in Absence of Trailer), Nr=rear cornering compliance modifier (Equal to 1 in Absence of Trailer), a=longitudinal distance from tow vehicle front axle to center of gravity (m), b=longitudinal distance from tow vehicle rear Axle to center of gravity (m), l=tow-vehicle wheelbase (m), e=longitudinal distance from tow vehicle rear axle to trailer coupling (m), c=longitudinal distance from trailer coupling to trailer center of gravity (m), d=longitudinal distance from trailer center of gravity to trailer axle (m), G=gravitational constant (9.81 m/s2/g) Mtv=total mass of tow vehicle (kg), and Mt=total mass of trailer (kg). - View Dependent Claims (2, 3)
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4. A method of steering rear wheels of a vehicle, the method comprising controlling a rear wheel steering actuator by varying it as a function of a position of the hand wheel and a speed of the vehicle, such that when a trailer is hitched to said vehicle said rear wheels are steered according to the formula:
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where;
R=rear wheel steer amount, F=front wheel steer amount, u=vehicle Speed (m/s), Df=front cornering compliance (deg/gravity), Dr=rear cornering compliance (deg/gravity), Nf=front cornering compliance modifier (Equal to 1 in Absence of Trailer), Nr=rear cornering compliance modifier (Equal to 1 in Absence of Trailer), a=longitudinal distance from tow vehicle front axle to center of gravity (m), b=longitudinal distance from tow vehicle rear Axle to center of gravity (m), l=tow-vehicle wheelbase (m), e=longitudinal distance from tow vehicle rear axle to trailer coupling (m), c=longitudinal distance from trailer coupling to trailer center of gravity (m), d=longitudinal distance from trailer center of gravity to trailer axle (m), G=gravitational constant (9.81 m/s2/g) Mtv=total mass of tow vehicle (kg), and Mt=total mass of trailer (kg). - View Dependent Claims (6)
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5. The method of 4 wherein said rear wheels are steered according to the formula:
Specification