Vehicle steering control

Details Vehicle steering control Vehicle steering control

1998-05-28

2001-01-23

Johnson, Brian L. (Department: 3611)

Motor vehicles

With means for detecting wheel slip during vehicle...

C180S244000, C701S082000

Reexamination Certificate

active

06176336

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to steering and traction control systems for vehicles.
BACKGROUND OF THE INVENTION
In a conventional vehicle having two or more pairs of wheels, one or more pairs of which are steerable, it is often easy for a driver to lose control due to sliding of the wheels when descending a steep slope or travelling on a slippery, low friction surface such as ice. One of the reasons for this is that when the front wheels start to slide the driver loses control of the steering. Inexperienced drivers tend to exacerbate the problem in such conditions by applying the brakes to try to control the speed of the vehicle. This simply increases slipping and further reduces steering control.
The present invention aims to overcome this problem by providing an automatic system for improving steering control.
SUMMARY OF THE INVENTION
Accordingly the present invention provides a drive system for a vehicle having a steerable wheel, the system comprising wheel slip measuring means for measuring the slip rate of said steerable wheel, drive means for driving said steerable wheel, and control means arranged to receive signals from said wheel slip measuring means, and to control the drive means to increase the driving torque to the steerable wheel if the negative slip rate of the steerable wheel is greater than a desired negative slip rate.
The present invention further provides a drive system for a vehicle having a steerable wheel, steering angle measuring means for measuring the steering angle of said steerable wheel, wheel slip measuring means for measuring the slip rate of said steerable wheel, torque demand means indicating a demand for torque from a driver of the vehicle, and torque control means arranged to monitor the slip rate measured by the measuring means and to control the torque supplied to said steerable wheel thereby to control said slip rate to a desired slip rate, wherein the desired slip rate is dependent on the torque demand and the steering angle.
In most cases the vehicle will have a pair of steerable wheels, usually the front pair. In such cases the drive means preferably enables the driving torque to each of the steerable wheels to be controlled independently. For example the drive means may comprise an electric motor for each steerable wheel, or a viscous coupling for each steerable wheel which can be controlled to vary the torque transmitted to each steerable wheel. However it will be appreciated that the measured slip rate and the desired slip rate could be based on an average between the two steerable wheels and in that case the drive means could be arranged to control the torque to the front pair of wheels, for example the torque supplied to a front differential.
The torque demand means will generally comprise an accelerator pedal for demanding a driving torque and a brake pedal for demanding a braking torque.
Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings.


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Japanese Abstract, vol. 95, No. 9 dated Oct. 31, 1995 & JP 07 156676 A (Suzuki) dated Jun. 20, 1995.

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