EP1526978A1

EP1526978A1 - Speed awareness device

Info

Publication number: EP1526978A1
Application number: EP03738295A
Authority: EP
Inventors: Alasdair John Southall
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-06-28
Filing date: 2003-06-30
Publication date: 2005-05-04
Also published as: AU2003244818A1; GB0215078D0; WO2004002769A1

Abstract

The invention relates to a speed awareness device for vehicles. The device comprises a speed limiting function and a speed alerting function and is adapted for use with a vehicle having an electronic road speed sensor. The device comprising a means to programme a vehicle speed into the device, wherein in use the device is adapted to compare vehicle speed with a pre-selected vehicle speed and is adapted to provide a speed awareness indication as the vehicle speed approaches the pre-selected speed. A device so arranged may help to prevent over speeding and may reduce the vehicle running costs and may also provide an improvement of corporate image. This may be particularly advantageous for the operators of company cars or commercial fleets. The device may also benefit the driver by protecting his or her livelihood by preventing speeding fines or even a driving ban.

Description

Speed Awareness Device

The present invention relates to a speed awareness device for vehicles and in particular, although not exclusively, to a selectable speed awareness device.

On some models of road going motor vehicle a facility exists to programme a speed and for there to be an acoustic warning if that speed is exceeded. The programming is a detailed operation requiring multiple steps and the selection of the desired speed by multiple use of a control button. The function is useful but the selection is lengthy and prone to errors. Further, the output is solely acoustic and may not be heard if the music system ofthe vehicle is playing loudly or if there is any extraneous noise.

It is further known to provide a speed limiting device for motor racing cars. Such a device is typically fitted to the ignition system so that the racing car cannot exceed a certain speed whilst in the pit lane of a racing circuit. The device provides an abrupt cut off to the engine if a certain vehicle speed is attained, for example by cutting the ignition or fuel to the engine. A graphical representation of the racing car speed limiter is illustrated in Figure 1. The Figure illustrates a rough saw tooth increase and decrease in speed as the vehicle approaches and drops back from the desired speed limit. This kind of speed limiting device is crude and produces a characteristic misfire sound to the engine at around the speed limit.

The racing car speed limiter permits the racing car to travel at the limit ofthe maximum permissible pit lane speed which is advantageous for motor racing. Whilst the rapid cut off speed limiting device may be suitable for a racing car in a pit lane it is entirely unsuitable for public road going vehicles and off road vehicles due to the pronounced misfire of the engine which may increase harmful emissions from the engine. This misfire is generally not advantageous and may damage the engine.

On many modern road vehicles there is no mechanical connection from the accelerator pedal to the engine. Instead the accelerator pedal has an electronic output which sends a control signal to the engine. This feature is advantageous for overcoming the problems ofthe prior art speed limiters and speed alert devices.

According to the invention there is provided a speed awareness device for use with a vehicle having an electronic road speed sensor, said device having programme means to programme a pre-selected vehicle speed wherein in use the device is adapted to compare road speed with said pre-selected speed and to provide a speed awareness indication as road speed approaches said pre-selected speed from below.

The speed awareness indication may be provided by vehicle speed control or by providing a speed alert signal. Controlling the vehicle speed is an active means of providing the awareness indication whereby providing a speed alert signal is a passive means of providing the awareness indication.

In a first embodiment, there is provided a speed limiting device for use with a vehicle having an electronic road speed sensor and an electronic accelerator pedal position sensor, said device comprising a speed input indicative of vehicle road speed, and a position input comprising a position signal indicative of accelerator pedal position, wherein in use the device is adapted to utilize said speed input to compare vehicle road speed with a pre-selected vehicle speed and to provide a modified position signal to permit vehicle engine speed to be restricted to a value equivalent to said pre-selected speed.

The vehicle engine speed can be restricted by an accelerator pedal actuator or most preferably by modifying the input to the Engine Control Unit (ECU) of the vehicle. Vehicle engine speed is restricted independently of the gear selected. When used to prevent overspeeding a device so arranged may reduce the vehicle running costs and may also provide an improvement of corporate image. This may be particularly advantageous for the operators of company cars or commercial fleets. The device may also benefit the driver by protecting his or her livelihood by preventing speeding fines, endorsements or even a driving ban. An important advantage of the invention is that the modified position signal to the ECU, whilst modified, remains of a normal kind. Accordingly operation of the ECU and engine is unaffected, and the vehicle manufacturers warranty can be maintained. Furthermore the normal engine emissions are unaffected by the device.

The vehicle road speed can be sensed electronically from any suitable sensor, for example from an electronic speedometer, or from a wheel speed sensor of an ABS or traction control device.

In an alternative embodiment the vehicle road speed is sensed by a global positioning system. This has the advantage of eliminating the requirement to make an electrical connection between the speed limiting device and the electronic road speed sensor.

The global positioning system may be already provided on the vehicle in the form of a navigational device such as a global mapping system. Alternatively the global positioning system may be provided in the form of a global positioning engine chip of the device.

In a preferred embodiment said programme means comprises a one touch apparatus.

A one touch apparatus for the purposes of this invention is, for example, an apparatus requiring one stroke of a key pad, one touch of a display screen, one flick of a toggle switch or in a preferred embodiment one push of a button. The simplified operation of the device over prior art devices advantageously provides minimum distraction to the driver and minimizes the time that the driver's eyes are not observing at the road.

An additional advantage of the system is an improvement in road safety for drivers, other road users and pedestrians. The device also provides a simplification and improvement over prior art speed limiters.

In one embodiment the device has a switching circuit to substitute said position signal for said modified position signal at a pre-determined threshold. Preferably the switching circuit is adapted to be controlled by a pilot signal, the pilot signal being an electronic binary signal. The switching circuit is typically triggered automatically as the vehicle road speed approaches said pre-selected speed. Said pre-selected speed may be selected at any time by the driver, or alternatively may be pre-programmed by the vehicle operator so that the switching circuit is triggered automatically at a certain vehicle road speed.

In a preferred embodiment the speed limiting device comprises a microprocessor and the switching circuit, the microprocessor having the position input comprising a position signal indicative of accelerator position and the speed input indicative of vehicle road speed, the modified position signal connected to the switching circuit, the pilot signal being provided by the microprocessor to the switching circuit, wherein the switching circuit connects one ofthe modified position signal and the position signal to a switch output thereof according to said pilot signal, the switch output being adapted for controlling engine speed. The switch output may for example be directly connected to an engine management system, in use.

The microprocessor continually monitors the device and operates the switching circuit when the device is functioning correctly, so that the modified position signal is selected when the vehicle road speed approaches said pre-selected speed. If the device ceases to operate correctly the pilot signal is removed and the position signal is selected so that the vehicle operates without the speed limiting function.

Such an arrangement permits switching from the position signal to the modified position signal, and is useful in a speed limiter and in dealing with failure modes ofthe device.

In a preferred embodiment the microprocessor compares the speed input with a pre-selected vehicle speed stored in a microprocessor memory at a rate of 100 times per second. In a preferred embodiment the microprocessor is adapted to allow the modified position signal to copy the position signal if the vehicle speed is below the pre-selected vehicle speed, less a predetermined value. This value defines a vehicle monitoring speed above which the position signal has progressively less effect on the modified position signal until the modified position signal is equivalent to the pre-selected vehicle speed limit. If the position signal is reduced the modified position signal will immediately follow so that the vehicle road speed can be slowed down as quickly as the driver requires.

In a preferred embodiment the pre-selected vehicle speed is compared with the vehicle road speed every 0.01s to permit the vehicle road speed can approach the pre-selected vehicle speed in a critically damped manner, and this provides a smooth transition rather than an abrupt cut-off.

Such a device provides an effective means of controlling vehicle road speed in a controlled manner and may also provide a fail-safe mode of operation for the device by allowing one ofthe normal and modified position signals to be selected in the event of failure ofthe other. For example, the position signal indicative of accelerator position is routed straight through the switching circuit if the microprocessor monitors a fault via a feedback input.

In a preferred embodiment the speed limiting device has a driver circuit between the modified position signal of the microprocessor and the switching circuit wherein the output from the driver circuit is connected to the feedback input ofthe microprocessor.

Advantageously the driver circuit has a display output which is connected to a display for showing that the device is in operation, and preferably for showing the pre-selected vehicle speed. The driver circuit amplifies the microprocessor signal to provide the necessary power for operating the display.

Preferably the device includes a selectable identity module to adapt input signals to a common format. For example the device can be adapted for use with vehicle specific sensors from different vehicles by the use of such an identity module. hi a preferred embodiment the speed limiting device has a console to provide means to generate a pre-selected vehicle speed signal. Preferably the console is connected to the microprocessor so that the console provides a pre-selected vehicle speed signal to the microprocessor.

Preferably the microprocessor is configured to perform the steps of initialising the device and testing for software and hardware integrity; performing a timing function to generate various timing intervals for measurement purposes; determining accelerator pedal position e.g. by potentiometer measurement; determining the vehicle road speed from the speed input; speed comparison by comparing the measured road speed with a pre-selected vehicle speed to determine whether vehicle road speed should be limited; optionally modifying the position signal if the vehicle road speed has exceeded the vehicle monitoring speed; passing said position signal to the engine management system of the vehicle if the vehicle road speed is below the vehicle monitoring speed; controlling vehicle engine speed if the vehicle road speed is above the vehicle monitoring speed; and completion of a self checking operation whereby the microprocessor regularly checks the modified position signal from the device is as required and that the switching circuit is operating.

Optionally the speed limiting device is provided with a memory which is adapted to store data relating to the number of times a pre-selected speed limit has been chosen. The device may be adapted to download the data via a download port or onto a removable memory card.

In another embodiment there is provided a speed alert device for use with a vehicle having an electronic road speed sensor, the sensor providing a speed input indicative of vehicle road speed, the device including a comparator and means for pre-selecting a vehicle speed comprising a one touch apparatus wherein the device is adapted to utilize said speed input to compare vehicle road speed with a pre-selected vehicle speed and to provide an alert signal if the vehicle speed is above the pre-selected vehicle speed. Such a device provides an alert signal at a pre-selected speed. The alert signal is typically an audible and/or a visual signal, requiring minimum input from the driver.

Preferably the alert signal continues after the pre-selected vehicle speed has been exceeded in use. The alert signal after the preselected vehicle speed has been exceeded may be a continuous or an intermittent signal. In the case of an intermittent signal the period between signals may decrease as the vehicle speed increases. The frequency of each intermittent signal may also increase as the vehicle speed increases. In the case of an audible signal the volume may increase as the vehicle speed increases.

Advantageously as the vehicle increases to the pre-selected vehicle speed a different alert signal is provided. The different alert signal may be a reduced intensity and/or an intermittent alert signal. Preferably the different alert signal is provided or commenced at approximately 95%- 100% ofthe pre-selected alert speed. This arrangement provides the advantage whereby the driver is made aware ofthe approaching pre-selected vehicle speed before it is exceeded.

Preferably the speed alert device comprises a plurality of one touch components to provide the alert signal and/or the different alert signal for a corresponding plurality of national speed limits.

The vehicle road speed can be sensed electronically from any suitable sensor, for example from an electrical speedometer, or from a wheel speed sensor of an ABS or traction control device. Alternatively the vehicle road speed is determined by a global positioning system ofthe vehicle or ofthe speed alert device.

Preferably the device has a speed input from the electronic road speed sensor, a display to provide information to the vehicle driver and a memory to store pre-selected vehicle speeds. Preferably the display can be illuminated. Illumination of the display may be used to indicate a change in the statutory speed limit. This change may be indicated by flashing ofthe illuminated display.

The speed limiting device and the speed alert device may further be adapted to obtain their operating power from an internal battery of the devices. Optionally the devices have solar powered cells to provide the required operating power. The devices may further be adapted to receive their operating power from a power socket such as a cigarette lighter socket.

The speed limiting device and the speed alert device may further be adapted for incorporation into a navigational system such as a global mapping system. Such a global mapping system may be adapted to store a road speed limit for a particular road whereby in combination with a global positioning system the speed limiting device or the speed alert device are adapted to automatically limit the vehicle speed or provide a warning signal to the vehicle driver respectively, when the vehicle is on the road. A device so arranged may provide a means for enforced vehicle speed control or speed alert on a particular road.

The features of the device to which the invention relates will be described in more detail with reference to the appended drawings in which:

- Figure 1 is a graphical representation of a Formula 1 speed limiting device.

- Figure 2 is a schematic representation of a hardware circuit for a selectable top speed limiter according to the present invention.

- Figure 3 is a schematic representation of the microprocessor configuration according to the present invention.

- Figure 4 is a graphical representation of intermittent monitoring of the vehicle speed signal. - Figure 5 is a graphical representation of continuous monitoring of the vehicle speed signal. - Figure 6 is a schematic representation of a top speed limiter according to the present invention.

- Figure 7 is a schematic representation of a top speed limiter according to an alternative embodiment.

- Figure 8 is a representation of speed alert device according to the present invention.

Referring firstly to Figure 2 there is shown a schematic representation of a hardware circuit for a selectable top speed limiter according to the invention, generally designated 10. The circuit 10 is suitable for limiting the speed of a vehicle with an electric speedometer having an input indicative of vehicle speed and an electric accelerator pedal connected to a potentiometer with a resistive output indicative of accelerator pedal position. The accelerator pedal may also have an actuator to change the position of the pedal. The circuit 10 may alternatively be configured to operate with an electric accelerator pedal having any form of electronic output to indicate pedal position.

The electronic position output of an accelerator pedal (not shown) is connected to the accelerator input A of a microprocessor 12. The electronic speed output from a speed sensor (not shown) is connected to the speed input B of the microprocessor 12. The speed sensor may be an analogue gear box device or a wheel hub mounted device which is part of a vehicle anti-lock braking system (ABS). Optionally an engine RPM output signal is connected to an engine RPM input R. The microprocessor 12 contains an engine RPM processing circuit. A 12v battery supply is connected to the C input of a power supply conditioning circuit 14. The power supply conditioning circuit 14 is connected to the circuit 10 to provide the required power in a stable manner. The microprocessor 12 has a modified electronic position output E which is fed to a driver circuit 16. The output F from the driver circuit 16 is monitored by the microprocessor 12 to ensure its correct operation. This is performed by a feedback input J to the microprocessor 12. The output F and input J provides a feedback loop to act as a fail-safe mechanism. The driver circuit 16 also operates a display 18 that is used to indicate correct operation of the circuit 10 e.g. by a green light. The output F from the driver circuit 16 also leads to a switching circuit 20. The input A is also connected to the output switching circuit 20. The switching circuit 20 is used to switch between the electronic position output of the accelerator pedal A and the modified electronic position output E to provide a final output D from the circuit 10 to an engine control unit (ECU). This switching is performed by a switching signal S from the microprocessor.

Normally the modified electronic position output E is selected, but the electronic position output will be routed through the output switching circuit 20 if the microprocessor 12 detects a fault. This will also cause the display 18 to indicate a fault condition e.g. by a red light. This is a watchdog type circuit that requires regular pulse outputs from the output F to maintain the selection of the modified electronic position output E. Therefore, in the case of an operational failure of the microprocessor 12, the circuit would revert to straight-through mode so that the electronic position output A is the final output D from the circuit 10.

The microprocessor 12 is configured to perform a number of functions which can be considered as a series of interconnecting blocks as illustrated in Figure 3. The first step is to initialise 22 the circuit 10 and test for software and hardware integrity. The microprocessor 12 is then configured to perform a timing function 24 to generate standard timing intervals for measurement purposes. Accelerator pedal position measurement 26 is performed at regular intervals by measuring the electronic position output. The microprocessor 12 performs speed measurement 28 by measuring the period of the input pulses to the vehicle's speedometer and averaging them e.g. 500 pulses averaged over 3 seconds. Speed comparison 30 is then completed by comparing the measured vehicle speed to a pre-selected value to determine whether the speed should be limited. The pre-selected value may be changed by the driver using a conveniently positioned keypad. Modification 32 of the accelerator pedal electronic position output is then performed to maintain the selected speed. Optionally the accelerator pedal drive is initiated to maintain the selected speed. The required amount of pedal drive is calculated according to the vehicle's speed and acceleration and the selected speed limit required. The circuit 10 performs the function of maintaining the selected speed to within a small tolerance below the limit. If the vehicle speed is below the vehicle monitoring speed the accelerator pedal electronic position output is passed directly to the output D. There is a short period after the need to limit the accelerator pedal electronic position output has ended when the circuit retains control over the output D. This ensures a smooth transition from limited to non-limited speed. The unit then completes a self checking 34 and a yes/no switch operation 35 of conventional kind whereby the microprocessor 12 regularly checks that the actual outputs from the circuit are as required and that the output switching circuit 20 is operating. If the switching circuit 20 is not operating then the microprocessor 12 will cease to update the watchdog circuit and the accelerator pedal electronic position output will pass straight through to the output D. The display controller 36 then sets the display to indicate when the circuit is not functioning and to give an indication of the cause of the fault condition.

The circuit 10 provides a smooth decay in vehicle acceleration up to the speed limit and is thus not a vehicle speed cut out. Specifically the microprocessor 12 performs a continuous critically damped operation to achieve smooth acceleration decay. Critical damping is a characteristic in which the selected speed limit is achieved as quickly as possible without subsequent vehicle speed oscillation. The continuous critical damping is switched on by the microprocessor 12 at a vehicle speed (v_moπitor) close to and below the selected speed limit (v_set). This is illustrated in Figures 4 and 5. Typically if the selected speed is 55mph the monitoring speed is approximately 50mph. In practice this produces a long wavelength of the acceleration decay with a very small amplitude of speed variation at the speed limit. This variation is barely detectable even when using sensitive laboratory measurement equipment. Results show that continuous monitoring is important to provide a smooth operation ofthe speed limiting device. Figure 4 shows results for intermittent monitoring and illustrates that vehicle speed is not critically damped whereas Figure 5 shows results for continuous monitoring and illustrates that vehicle speed is critically damped. If the accelerator position sensor senses an accelerator position corresponding to less than v_monitor the microprocessor 12 copies the accelerator pedal electronic position to the modified electronic output and hence to the output D. If the vehicle is travelling downhill and starts to increase in speed the circuit will send a signal to the engine management system to slow the vehicle speed back to the speed limit in a critically damped manner. This is achieved by the device measuring the electronic speed output indicative of vehicle speed and comparing it with the pre-selected speed. If the device detects that the vehicle speed is greater than the pre-selected speed the accelerator pedal electronic position output is reduced so as to reduce the engine speed.

The selectable speed limiter is intended to be a small, easily retrofitable unit. Physically the unit consists of electric components mounted and potted in an enclosure with fixing holes, which enable attachment within the engine compartment. Connections to the units are by flying-leads using sealed joining connectors to the accelerator pedal position sensor and the vehicle speed sensor. The unit is sealed to prevent tampering. Two Light Emitting Diodes (LEDs) are also provided, one of which is a green LED and is lit when the ignition is on and when the unit is functioning correctly. The other of which is red and is lit when the unit has failed or when it has been bypassed.

The operation of the selectable speed limiter is as follows. When the power is first supplied a normally closed switching circuit 20 will pass the accelerator pedal electronic position output straight through to the ECU unchanged. If the selectable speed limiter fails then the engine operates as if it was not fitted. The limiter then performs a self check of standard and known type. If the self check indicates that the limiter is functioning correctly the switching circuit 20 opens and the modified electronic position output is fed to the ECU of the vehicle. At this stage the LED is illuminated to show that the limiter is functioning correctly. The rate of pulses from the speed sensor is constantly compared with the specified threshold value equivalent to the selected speed limit. If the threshold is exceeded the limiter prevents the modified electronic position output from increasing further. If the speed of the vehicle continues to increase, possibly due to the vehicle going downhill, then the modified electronic position output is decreased which slows the vehicle. If the speed of the vehicle drops below the limit the modified electronic position output is increased towards the accelerator pedal electronic position output. This increase is carried out gradually to prevent a possible sudden power surge from the engine which would result in a vehicle speed surge. The selectable speed limiter incorporates a selector box which is separate from the switching logic as illustrated in Figure 2. The selectable speed limiter is programmed by the manufacturer so that the customer is required to push one button on the selector box to set the speed limiter to that speed limit. The speed limiter is programmed by downloading a file into the device whereby the file relates to the vehicle on which the limiter is fitted. Typically buttons of 20, 30, 40, 50, 60 and 70 miles per hour (or the appropriate kilometres per hour) are provided on an easy to use console. The selectable speed limiter may have a visual or audible warning that a certain speed has been reached.

Now referring to Figure 6 there is shown a schematic of a top speed limiter generally designated 38. The circuit 38 is suitable for limiting the speed of a vehicle with an electric speedometer having an input indicative of vehicle speed and an electric accelerator pedal connected to a potentiometer with a resistive output indicative of accelerator pedal position. The accelerator pedal may also have an actuator to change the position ofthe pedal. The circuit 38 may alternatively be configured to operate with an electric accelerator pedal having any form of electronic output to indicate pedal position. The top speed limiter 38 has red and green LEDs 40 which are lit to indicate when the ignition is on and when the limiter 38 is functioning correctly. The limiter 38 has an accelerator position sensor 42 and a vehicle speed sensor 44. These sensors 42, 44 provide the input signal to the limiter 38. The accelerator position sensor 42 senses the signal to be modulated. One of the outputs of the vehicle speed sensor 44 continues to the ECU 45. The modified output G from the limiter 38 continuing to the ECU 45.

The top speed limiter 38 is programmed by the manufacturer and not by the customer and operates in an identical manner to the selectable speed limiter except that it does not have a selector box to allow the driver to set the speed limit. The microprocessor of the top speed limiter 38 is configured to operate in an identical manner to the selectable speed limiter 10. The top speed limiter 38 is intended to be a small, easily retrofit unit. Referring now to Figure 7 there is shown an alternative embodiment for a top speed limiter, generally designated 60. hi Figure 7 like features of the embodiment of Figure 6 are shown with line reference numerals. The top speed limiter 60 of Figure 7 differs from the embodiment of Figure 6 by incorporating a global positioning system 62 which is used to measure vehicle road speed. The global positioning system may already be provided on the vehicle to which the limiter 60 is fitted or may be part ofthe limiter 60.

An engine revolutions per minute (RPM) sensor 64 and an engine RPM processor 66 are also shown in Figure 7 as an additional arrangement to control vehicle speed. The engine RPM processor 66 contains the programming necessary for an engine RPM limit to be applied. The processor 66 may also incorporate the necessary electrical circuits to modify the engine ECU input signal accordingly. The maximum engine RPM may be restricted to 3500 RPM which might equate to a maximum road speed for the vehicle of 70 mph when the vehicle is in top gear. In this manner the engine RPM sensor 64 and processor 66 can be used to provide an additional arrangement to limit vehicle speed. The maximum speed of the vehicle in each gear is limited to a value equivalent to the maximum engine RPM. The maximum engine RPM is controlled by the processor 66 by controlling an engine parameter such as the amount of fuel provided to the engine. A vehicle fitted with such an engine RPM limiter may provide the engine with greater longevity since the engine has not been run at a high RPM. Accordingly a vehicle fitted with such an engine RPM limiter may have a greater residual value when the vehicle is sold.

Now referring to Figure 8 there is shown a representation of a speed alert device generally designated 46 according to a second aspect of the present invention. The device 46 does not use an accelerator input and is suitable for a vehicle with an electric speedometer having an input indicative of vehicle speed. The main differences of the speed alert device 46 with the top speed limiter 38 of Figure 6 are that the speed alert device 46 has an audible or visual signal to alert the driver that a certain speed has been exceeded. The speed alert device 46 utilizes the same button console as the selectable speed limiter to provide a one push button operation 48 to give a warning that a speed of 10, 20, 30, 40, 50, 60 or 70 miles per hour (mph) (or any other desired speed or an appropriate speed in kilometres per hour) is being exceeded. The speed alert device 46 does not have any connection to the ECU and only has an input from the electrical speed sensor indicated H. Switches are contained within the device 46 for issuing an alert signal for selected vehicle speeds. It is, therefore, much less complex than the speed limiters 10, 38 described above and is correspondingly less expensive to manufacture. It may appeal to the accessory end of the car market making it a popular device applicable to any car with an electrical speedometer. Since there is no connection to the ECU there is unlikely to be any likelihood of invalidating vehicle warranty.

The speed alert device 46 may also appeal to the very small 'fleet' of one or two cars or vans. The device 46 overcomes the potential reservations that drivers may have about using a speed limiter which compulsorily limits the speed of their vehicle. In order to minimise the problems of fitting the speed alert device the unit is intended to be programmed by the driver, customer or person fitting the device 46. The programming procedure for the device 46 is as follows. The driver drives the vehicle steadily at the required speed and presses the appropriate speed button. If a different speed button is pressed then the unit will not be programmed. This procedure is repeated for each speed button on the console. The microprocessor memory remembers the speed input signal for each of the other speed buttons. When the driver requires a warning signal for a given speed the appropriate speed button is pressed. If the vehicle exceeds that speed the device 46 produces an acoustic/audible alarm to sound and causes the backlight of the button to flash. If the exterior lights ofthe vehicle are on then all ofthe buttons are illuminated with the selected button being illuminated to an increased brightness. If the exterior lights of the vehicle are illuminated the lights ofthe buttons of the console are dimmed uniformly but the selected button is brighter than the others. This function requires a further input to the device 46 from a signal of the vehicle indicating that the exterior lights are on.

In a preferred embodiment the speed alert device 46 is programmed by driving the vehicle at 40 mph and by pressing the 40 mph speed button. The device 46 then completes a self-programming routine whereby the speeds of 10, 20, 30, 50, 60, 70, 80 mph are calculated and automatically assigned to corresponding speed buttons on the console. The user then selects a speed from the console at which an alert signal is to be provided.

A preferred embodiment of the speed alert device 46 box measures approximately 55mm x 30mm x 15mm and is mounted onto the dashboard or console of the vehicle using a suitable mounting system. Four wires are lead from the device 46 and are connected to an earth, a live, the signal wire from the speedometer sender and the light switch.

The speed limiters 10, 38, 60 and speed alert devices 46 help drivers to keep to the statutory or imposed speed limits. This in turn helps road safety and the safety of pedestrians. In the case of the devices 10, 38, 60 and 46 the speed of the vehicle is either controlled or communicated audibly to the driver which minimizes the requirement for the driver to look away from the road to either operate the devices 10, 38, 60 and 46 or to look at the vehicle speedometer. In this manner the devices 10, 38 and 46 contribute to road safety. Optionally the alert speed or speed limit may be selected by voice activation. This may further eliminate the requirement for a driver to look away from the road to operate the devices 10, 38, 60 or 46. The devices may also reduce the number of speeding convictions and disqualifications which protecting the drivers' livelihood by reducing job losses due to speeding offences. Correspondingly the systems 10, 38, 46 may reduce the number of accidents and the severity of accident injury. The devices also help companies to comply with health and safety legislation as well as helping to maintain company image and reputation. A further benefit to the fleet operator may be a reduction in insurance premiums when the systems are fitted fleet wide. The devices 10, 38, 46 may be fitted to land sea and air vehicles including off road vehicles such as tractors, four wheel drive vehicles or fork lift trucks. Whilst preferred embodiments for the devices have been described it will be appreciated that a speed limiter or a speed alert device according to the present invention could be achieved by any number of alternative designs.

Claims

1. A speed awareness device for use with a vehicle having an electronic road speed sensor, said device having programme means to programme a pre-selected vehicle speed wherein in use the device is adapted to compare road speed with said pre-selected speed and to provide a speed awareness indication as road speed approaches said pre-selected speed from below.

2. A device according to claim 1, wherein said programme means comprises a one touch apparatus.

3. A device according to claim 2, wherein a plurality of one touch components are provided to select different pre-selected vehicle speeds.

4. A device according to claim 3, wherein one or more of said one touch components correspond to a national speed limit.

5. A device according to any of claims 1-4, and having a position input comprising a position signal indicative of accelerator pedal position; a speed input indicative of vehicle road speed; a comparator for comparing said speed input with said pre-selected speed, and for generating a modified position signal adapted to restrict vehicle engine speed to a value equivalent to said pre-selected speed.

6. A device according to claim 4, and further including a switching circuit adapted to substitute said modified position signal for said position signal at a pre-determined threshold.

7. A device according to claim 6, wherein said device is adapted to generate a pilot signal to actuate said switching circuit.

8. A device according to claim 6 or claim 1, and further comprising a microprocessor.

9. A device according to claim 8, wherein said microprocessor is adapted to compare said speed input with said pre-selected vehicle speed at a rate of 1000 times per second.

10. A device according to claim 8 or claim 9, and further including a driver circuit having a driver input comprising said modified position signal, and a driver output connected to said switching circuit and as a feedback input to said position input.

11. A device according to claim 9, and further including a display adapted to indicate that the device is operational, wherein the driver circuit has a display output connected to said display.

12. A device according to claim 11, wherein said display is adapted to show said pre-selected speed.

13. A device according to claim 11 or claim 12, wherein the display is adapted to be illuminated.

14. A device according to claim 1 or claim 2 and adapted to provide a first awareness indication as vehicle speed approaches said pre-selected speed, and a second awareness indication if said vehicle speed exceeds said pre-selected speed.

15. A device according to claim 14, wherein said second awareness indication is intermittent.

16. A device according to claim 15, wherein the frequency of said second awareness indication increases as vehicle speed increases.

17. A device according to any of claims 14-16, wherein the first awareness indication is provided as substantially 95-100% of said pre-selected speed.

18. A device according to any preceding claim, and further comprising means for connection to a power supply.

19. A device according to claim 18, wherein the power supply is a solar panel.

20. A device according to any preceding claim, wherein the road speed is determined by a global positioning system.

21. A device according to any preceding claim, and further comprising a memory which is adapted to store data relating to the number of times that a pre-selected vehicle speed has been chosen.

22. A device according to claim 21, wherein the data is adapted to be downloaded onto a removably memory card.

23. In combination a device according to any preceding claim and a vehicle.

24. A method of operating a vehicle speed awareness device and comprising the steps of: determining vehicle accelerator pedal position from an electronic pedal position signal; determining vehicle road speed; pre-selecting a desired vehicle speed; comparing vehicle road speed with said pre-selected vehicle speed; generating a modified pedal position signal adapted to restrict engine speed to a value equivalent to said pre-selected vehicle speed as said vehicle road speed approaches said pre-selected speed.

25. A method according to claim 24 and further including the steps of: determining a vehicle monitoring speed less than said pre-selected speed; causing said modified pedal position signal to be substituted for said pedal position signal if vehicle road speed exceeds said vehicle monitoring speed.