Four wheel steering system and method for trailering

US 6,735,507 B2
Filed: 06/04/2003
Issued: 05/11/2004
Est. Priority Date: 06/28/2002
Status: Expired due to Fees

First Claim

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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:

$R \approx \frac{D_{r} \cdot N_{r} \cdot u^{2} - 57.3 \cdot b \cdot G}{D_{f} \cdot N_{f} \cdot u^{2} + 57.3 \cdot a \cdot G} \times F$ where;

$N_{f} = 1 - \frac{M_{t}}{M_{tv}} (\frac{d}{d + c}) \frac{e}{b}, N_{r} = 1 + \frac{M_{t}}{M_{tv}} (\frac{d}{d + c}) (\frac{l + e}{a}),$ R=rear wheel steer amount, F=front wheel steer amount, u=vehicle Speed (m/s), D_f=front cornering compliance (deg/gravity), D_r=rear cornering compliance (deg/gravity), N_f=front cornering compliance modifier (Equal to 1 in Absence of Trailer), N_r=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) M_tv=total mass of tow vehicle (kg), and M_t=total mass of trailer (kg).

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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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6 Claims

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:
- $R \approx \frac{D_{r} \cdot N_{r} \cdot u^{2} - 57.3 \cdot b \cdot G}{D_{f} \cdot N_{f} \cdot u^{2} + 57.3 \cdot a \cdot G} \times F$ where;
  
  $N_{f} = 1 - \frac{M_{t}}{M_{tv}} (\frac{d}{d + c}) \frac{e}{b}, N_{r} = 1 + \frac{M_{t}}{M_{tv}} (\frac{d}{d + c}) (\frac{l + e}{a}),$ R=rear wheel steer amount, F=front wheel steer amount, u=vehicle Speed (m/s), D_f=front cornering compliance (deg/gravity), D_r=rear cornering compliance (deg/gravity), N_f=front cornering compliance modifier (Equal to 1 in Absence of Trailer), N_r=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) M_tv=total mass of tow vehicle (kg), and M_t=total mass of trailer (kg).
- View Dependent Claims (2, 3)
- - 2. The steering system of claim 1 wherein said rear steering amount is defined by:
    - $R = \frac{D_{r} \cdot N_{r} \cdot u^{2} - 57.3 \cdot b \cdot G}{D_{f} \cdot N_{f} \cdot u^{2} + 57.3 \cdot a \cdot G} \times F .$
  - 3. The steering system of claim 1 wherein said controller includes a look-up table having data determined at least in part using said formula.

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:
- $R \approx \frac{D_{r} \cdot N_{r} \cdot u^{2} - 57.3 \cdot b \cdot G}{D_{f} \cdot N_{f} \cdot u^{2} + 57.3 \cdot a \cdot G} \times F$ where;
  
  $N_{f} = 1 - \frac{M_{t}}{M_{tv}} (\frac{d}{d + c}) \frac{e}{b}, N_{r} = 1 + \frac{M_{t}}{M_{tv}} (\frac{d}{d + c}) (\frac{l + e}{a}),$ R=rear wheel steer amount, F=front wheel steer amount, u=vehicle Speed (m/s), D_f=front cornering compliance (deg/gravity), D_r=rear cornering compliance (deg/gravity), N_f=front cornering compliance modifier (Equal to 1 in Absence of Trailer), N_r=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) M_tv=total mass of tow vehicle (kg), and M_t=total mass of trailer (kg).
- View Dependent Claims (6)
- - 6. The method of claim 4 wherein said controlling includes using a lookup table populated with data determined in part using said formula.

5. The method of 4 wherein said rear wheels are steered according to the formula:
- $R = \frac{D_{r} \cdot N_{r} \cdot u^{2} - 57.3 \cdot b \cdot G}{D_{f} \cdot N_{f} \cdot u^{2} + 57.3 \cdot a \cdot G} \times F .$

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Current Assignee
Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
Original Assignee
Delphi Technologies, Inc. (BorgWarner Incorporated), General Motors Corporation (General Motors Company)
Inventors
Grougan, Paul A., Boswell, Karen A., Klein, Steven D., Zebehazy, Thomas C., Norman, Kenneth D., Worner, Charles R., Sherman, Scott P.
Primary Examiner(s)
Chin, Gary

Application Number

US10/454,447
Publication Number

US 20040002800A1
Time in Patent Office

342 Days
Field of Search

701/41, 701/42, 180/408, 180/409, 180/410, 180/411, 180/412, 180/413, 180/414, 180/415, 180/416, 180/443, 180/444, 180/445, 180/446
US Class Current

701/41
CPC Class Codes

B62D 7/159 characterised by computing ...

Four wheel steering system and method for trailering

First Claim

22 Assignments

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Abstract

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6 Claims

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Four wheel steering system and method for trailering

First Claim

22 Assignments

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Abstract

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Specification

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