GB2379750A

GB2379750A - An adaptive cruise control and forward alert system

Info

Publication number: GB2379750A
Application number: GB0213697A
Authority: GB
Inventors: Dale Corrigan; Ian Phillip Blake; Philip Alexander Barber; Paul Robert Haney
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2001-06-29
Filing date: 2002-06-14
Publication date: 2003-03-19
Anticipated expiration: 2022-06-14
Also published as: GB0213697D0; GB2379750B; WO2003002367A1; EP1399326A1; GB0115922D0

Abstract

A vehicle is described which is fitted with both an adaptive cruise control system ACC and a forward alert warning system FAW, each of the two systems is selectively capable of actuation by the vehicle driver independently of the other. The adaptive cruise control system ACC includes manual setting means 24, 26 for enabling the driver to set the desired headway. The same manual setting means 24, 26 additionally serve to set the sensitivity of the forward alert warning system when the latter is actuated by the driver.

Description

- 1 - Warning System The present invention relates to a forward alert or

collision warning system for a motor vehicle that serves to 5 warn a driver of impending danger.

Forward alert or collision warning systems that estimate a level of danger when they predict that a threshold level of deceleration will need to be exceeded in lo order to avoid a collision. Such system receive signals indicative of the vehicle speed and signals from a forward looking radar indicative of the distance to the vehicle or obstacle ahead. From derivatives of these signals and classical Newtonian mechanics, the system can estimate the 15 distance at which the vehicle ahead will come to a stop (assuming it maintains its current level of deceleration) and the deceleration required of the vehicle in which the system is installed for it to come to a stop inside that distance and thereby avoid collision. Should the level of so deceleration exceed a given threshold, then a warning is given to the driver.

Depending on the driver's preferences, forward alert warning systems are regarded by drivers as being either too 25 cautious or too optimistic. A warning system that is too sensitive will provide an alarm signal in situations where the driver does not require one, for example during his/her normal driving style, if the driver is in the habit of braking harder than the chosen deceleration threshold. A so system with low sensitivity on the other hand will not provide a warning until the situation has developed to a higher level of danger than one with which the driver is comfortable. The optimum sensitivity will vary not only from driver to driver but also from one time to another with the 35 same driver.

- 2 For the above reasons, warning systems have come to be regarded as a nuisance or else they have been perceived as being useless. To avoid the above problem, it is known from US-5,631,639 to provide a vehicle forward alert warning system that includes a selector which allows the driver to set the alarm sensitivity.

Forward looking radar is currently used not only in forward alert warning systems but also in adaptive cruise lo control system. Normal cruise control systems only act to maintain a constant vehicle speed and may result in the system vehicle driving too close to the vehicle ahead. With adaptive cruise control, on the other hand, an additional control is provided to set the desired headway, this being 15 indicative of the time between the vehicle ahead and the system vehicle passing the same point on the road. The headway is of course not a fixed distance but one that increases as the vehicle speed increases.

so In a vehicle, fitted with both types of system, there is a confusing proliferation of controls and settings.

With a view to mitigating the foregoing disadvantage, the present invention provides a vehicle fitted with both an :s adaptive cruise control system and a forward alert warning system, each of the two systems being selectively capable of actuation by the vehicle driver independently of the other, wherein the adaptive cruise control system includes manual setting means for enabling the driver to set the desired so headway, which manual setting means additionally serve to set the sensitivity of the forward alert warning system when the latter is actuated by the driver.

In present invention, in a vehicle fitted with both s forward alert warning and adaptive cruise control systems, the same control as is used by the driver to set the headway in the adaptive cruise control system serves as the means

- 3 for adjusting the reference deceleration limit in the forward alert warning system.

When either one of the forward alert warning and 5 adaptive cruise control system is actuated, the same control will serve to set the headway or acceleration threshold. The control is intuitive as both these settings will depend in the same way on the driver's current driving style. When an aggressive driving style is adopted, the driver will wish to 10 set a reduced sensitivity of the forward alert warning system and a reduced headway of the cruise control system.

Moving the control in a manner to reduce the current setting will therefore achieve either of these objectives.

If both system are actuated at the same time, then the setting of the headway will automatically correctly dictate the sensitivity of the forward alert warning system avoiding the driver having to find a balance between two separate controls. The manual setting means preferably comprise UP/DOWN buttons, but it would be alternatively possible to provide a linear slider or a rotary control knob.

25 The invention will now be described further, by way of example, with reference to the accompanying drawing, which is a highly schematic block diagram illustrating the present invention. so The drawing shows an adaptive cruise control system ACC and a forward alert warning system FAW. Each of the ACC and FAW systems includes a microprocessor 10, 110 which is connected to a respective ON/OFF button 12,112 and to a radar sensor 14, 114 which determines the distance between 35 the system vehicle and the vehicle ahead.

- 4 The term "radar" is used herein to include any means of estimating the distance to the vehicle ahead, regardless of the nature of the energy that is transmitted and reflected.

In particular, it may rely on infrared radiation rather than 5 radiation in the microwave band. To avoid confusion, the term "the system vehicle' is used herein to refer to the vehicle to which the warning system is fitted in order to distinguish it from "the vehicle ahead", i.e. the vehicle being followed by the system vehicle.

The microprocessors 10 and 110 and radars 14, 114 can be considered as separate items but they are of course one and the same and it is only the tasks performed by the microprocessor that provide alarm warnings or set the 5 vehicle speed.

The ACC system is actuated by operating the ON/OFF button 12. When operative, the microprocessor 10 receives signals indicating the current speed of the vehicle and So compares it with a speed that is stored in memory when a SET button 18 is depressed. The microprocessor then acts on the vehicle speed controls 22 (which can include the demand pedal, the brakes and the transmission ratio) in order to match the actual speed with the desired speed. This is the 25 conventional cruise control function which can be temporarily disabled by clearing the memory, which occurs when the RESET button 20 is depressed or when the driver applied the brakes.

So The "adaptive" aspect of the cruise control is achieved with the aid of the signal from the radar 14. When the headway (measured in units of time rather than distance) between the system vehicle from the vehicle ahead drops below a certain threshold then the vehicle speed is reduced 5 to a value below the maximum speed set by the driver to avoid driving too near to the vehicle ahead. The headway is set by the driver using the UP/DOWN buttons 24 and 26.

- The forward alert system FAW is switched on by the driver using the button 112. The reason for having a button to switch the FAW system off is that during town driving the system tends to produce too many unwanted alarm warnings and 5 becomes an irritation to the driver rather than a safety feature. While the FAW system is operative, the microprocessor 110 constantly performs calculations on the distance from 10 the vehicle ahead, to ascertain the speed and deceleration of the vehicle ahead. This allows the microprocessor to predict where the vehicle ahead will come to a standstill if it continues to decelerate at its current rate and the distance within which the system vehicle will need to come 15 to a stop to avoid colliding with the vehicle ahead. This level of deceleration required to avoid collision is compared with a preset threshold and an alarm warning generator 116 which produces visible and audible signals is activated to alert the driver to the danger ahead and 20 thereby allow the driver to take early evasive action.

In accordance with the invention, the deceleration threshold is preset by the driver using the same UP/DOWN buttons 24 and 26 as used by the ACC system to set the 25 headway. These button, in common with the SET and RESET buttons 18 and 20 and the ON/OFF buttons 12 and 112 may conveniently be mounted on the steering wheel of the vehicle for ease of operation by the driver.

so Using the same buttons 24 and 26 to set two different but intuitively related parameters reduced the total number of buttons thereby avoiding confusion to the driver at the same time as reducing system cost.

Claims

1. A vehicle fitted with both an adaptive cruise 5 control system and a forward alert warning system, each of the two systems being selectively capable of actuation by the vehicle driver independently of the other, wherein the adaptive cruise control system includes manual setting means for enabling the driver to set the desired headway, which lo manual setting means additionally serve to set the sensitivity of the forward alert warning system when the latter is actuated by the driver.

2. A vehicle as claimed in claim 1, wherein the 15 manual setting means comprise of UP/DOWN buttons.

3. A vehicle as claimed in claim 1 or 2, wherein the manual setting means are mounted on a steering wheel of the vehicle.

4. A vehicle fitted with both an adaptive cruise control system and a forward alert warning system, constructed substantially as herein described with reference to and as illustrated in the accompanying drawing.