Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-08-24
2001-06-05
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S093000, C180S179000, C123S352000
Reexamination Certificate
active
06243640
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to control of a vehicle braking system, and in particular to the use of the braking system to control the descent of hills by the vehicle. It is particularly useful for off-road vehicles.
BACKGROUND TO THE INVENTION
It is known from WO 96/11826 to provide a brake control system for a vehicle in which the brakes are automatically controlled so as to limit the vehicle speed to a predetermined value, the target speed, such that, with the help of an anti-lock brake function, the descent of a steep hill can be controlled without the need for skilled inputs from the driver.
It can be a problem with such a system, when it is first actuated, to control the vehicle speed smoothly as it approaches the target speed. It is known from GB2319636 to provide a system in which a control speed is ramped downwards from an initial value which is higher than the instantaneous vehicle speed towards the target speed, which is lower than the instantaneous vehicle speed. However problems can still occur in providing a smooth transition when the control speed reaches the instantaneous vehicle speed.
SUMMARY OF THE INVENTION
The present invention provides a braking system for a vehicle, the system comprising brakes, a vehicle speed sensor for measuring the speed of the vehicle, and a controller having a target speed and a maximum rate of change of acceleration defined therein and being arranged to control application of the brakes so as to bring the speed of the vehicle towards the target speed, wherein the controller is arranged, as the vehicle speed approaches the target speed, to control the vehicle brakes so that the magnitude of the rate of change of acceleration of the vehicle does not exceed said maximum rate of change of acceleration.
The term rate of change of acceleration is used herein to mean a rate of change of positive acceleration or a rate of change of negative acceleration, and negative acceleration is referred to as deceleration where this improves clarity.
The maximum value can be the same whether the vehicle is accelerating towards the target speed or decelerating towards the target speed.
The present invention further provides a method of controlling the brakes of a vehicle so as to bring the vehicle speed towards a target speed, the method comprising the steps of defining a maximum rate of change of acceleration, measuring the rate of change of acceleration of the vehicle, and controlling the brakes so that the magnitude of said rate of change of acceleration of the vehicle so that it does not exceed said predetermined maximum value.
An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings.
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Chin Gary
Davis & Bujold P.L.L.C.
Rover Group Limited
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