GB2454516A

GB2454516A - Vehicle speed control

Info

Publication number: GB2454516A
Application number: GB0722081A
Authority: GB
Inventors: Richard Picton
Original assignee: Nissan Motor Manufacturing UK Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2007-11-12
Filing date: 2007-11-12
Publication date: 2009-05-13
Also published as: GB0722081D0

Abstract

A human machine interface (HMI) is provided for an adaptive speed limiter. The HMI comprises a display configured to communicate to the driver the current speed limit; and an indication that the current speed limit is being exceeded; and a switch module including a SET button configured to permit the driver to set the maximum speed of the vehicle to the speed limit.

Description

IMPROVEMENTS IN OR RELATING TO VEHICLE SPEED CONTROL

The present invention relates to an adaptive speed limiter and a Human Machine Interface (HMI) for delivering the functionality of the adaptive speed limiter to the driver of a vehicle.

There is currently a trend, in both automotive and road design, towards increased complexity. Today's driver is expected to interact with an increasing number of complex systems whilst driving, for example taking instructions from a satellite navigation system.

In addition to the internal complexity of today's driving experience, the driver is confronted with a plethora of traffic signs. In parallel with the increased signage, there has been a proliferation of speed cameras which means that a driver's failure to see and react to each of the many speed limit signs is frequently punished by a fine and possibly points on the driver's licence.

Whilst some drivers deliberately drive well above the speed limit, the vast majority of speeding fines result from inadvertent speeding. A vehicle's speed may accidentally exceed the speed limit because the driver does not recognise the applicable speed limit for a given section road at a given time. Furthermore, the vehicle's speed may gradually increase as a result of the road layout or the behaviour of other traffic. In either of these scenarios the driver can be fined for speeding when it was never his intention to flout the law.

The automotive industry has already provided a number of tools for the driver in order to help the driver to avoid inadvertent speeding.

Heavy goods vehicles are often provided with speed limiters which are incorporated into or connected to the engine control unit. These speed limiters prevent the vehicle from exceeding a fixed maximum speed. This speed typically corresponds to the vehicle's maximum legal speed on the free-way, autobahn or motorway.

Furthermore, some passenger vehicles are provided with speed limiters that allow the driver to set the current speed of the vehicle as a limit for the vehicle as it continues a journey.

Many cars are now provided with cruise control systems. These systems typically operate by setting the vehicle to cruise at the speed at which the vehicle is travelling when the system is activated. The driver then relinquishes control of the speed of the vehicle and removes his foot from the accelerator pedal. The speed at which the vehicle travels can be altered incrementally by pressing a +/-" button provided conveniently for the driver. The system is typically cancelled when the driver touches either the brake or clutch. These systems can be highly effective for long journeys on motorways or freeways as the driver is unlikely to have to touch the brake or clutch for extended periods of time. However, these systems are much less appropriate within the context of urban driving when a more responsive driving style is required.

Many cars also have satellite navigation systems which are either built into the vehicle and provided at point of sale or, alternatively, they are non-vehicle specific systems that are purchased and temporarily installed within the vehicle by the owner for the duration of a journey. Satellite navigation systems are typically provided with map data that includes some indication as to the speed limit that is in place.

However, it is not uncommon for the speed limit to vary, either as a result of road works, or road hazards such as high volume of traffic, heavy rain or fog. In these cases the temporary speed limit is displayed either in road side signs or, more commonly on motorways, on overhead gantries.

In order to try to improve the reliability of information provided by satellite navigation systems, these systems are sometimes combined with systems designed to detect and recognise traffic signs. Once such system from Siemens, is described in US 2006/0034484. This system improves on previous systems that have relied on a two stage recognition process comprising detection and subsequent classification steps.

The Siemens system uses a video sequence comprising a plurality of image frames.

The content of these frames is filtered and further processed using data from multiple frames of the video data in order to identify a traffic sign. The sign is then classified as a particular type of sign. This system can then supply the driver with more reliable information about the current speed limit that is applicable on the section of road on which he is driving, US 2006/0034484 also suggests that this information can be incorporated into an adaptive cruise control system.

Whilst the incorporation of a traffic sign recognition system will improve an adaptive cruise control system, it will not address the issue of responsive driving within the urban environment.

It is against this background that the present invention has been made.

According to the present invention there is provided a human machine interface (HMI) for an adaptive speed limiter, the HMI comprising: a display configured to communicate to the driver the current speed limit, and an indication that the current speed limit is being exceeded, and a switch module including a SET button configured to permit the driver to set the maximum speed of the vehicle to the speed limit.

The SET button is the only button that the driver needs to press in order to accept the new maximum speed of the vehicle. It is not necessary to cancel any previous maximum speed or to move step-wise from a previously set value.

The switch module may further comprises a rocker switch to allow the maximum speed to be altered. Although the provision of a single button set procedure is very convenient for setting a new maximum speed, the provision of a rocker switch gives the user additional freedom to adapt the system according to personal preference.

The display may further comprise an indication as to the status of adaptive speed limiter system. The status is selected from a list including inactive, set and active. This can be indicated using different colours so that the driver can tell at a glance whether the system is inactive, denoted by a white or blank icon; set, denoted by a green icon, and active, denoted by an orange icon.

The display may further comprise an indication of the value of the speed limit that is currently set in the adaptive speed limiter. By displaying the current set value the driver can check at a glance whether or not this matches the current speed limit that is also shown on the display. This is especially useful when travelling through an area with frequent changes to the speed limit.

The HMI may further comprise an audible warning system configured to be activated when the speed of the vehicle exceeds the speed to which the adaptive speed limiter is set. The provision of an audible warning system enables the driver to be made aware that the vehicle speed is exceeding the speed to which the adaptive speed limiter is set.

This is particularly useful when the vehicle is driving down an incline and therefore accelerating as a result of the road topology rather than because the engine is forcing the vehicle to accelerate.

Furthermore, according to the present invention there is provided an adaptive speed limiter system for use in a vehicle, the adaptive speed limiter system comprising: a speed limit information provider, an HMI as previously described, wherein the display of the HMI is configured to display the speed limit information provided by the speed limit information provider, and a speed limiter connected to the switch module of the HMI and configured to limit the maximum speed of the vehicle to the speed accepted by the driver using the SET button.

The HMI provides a single button for the activation of the system and also for the acceptance of a new speed limit. This provides a very simple interface that is easy for the driver to understand. The provision of a speed limiter that is adaptive means that the system only impinges on the usual driving experience when the vehicle would otherwise be exceeding the speed limit. Whilst the vehicle is being driven at a speed below the speed limit the system does not change the driving experience at all. However, the speed limiter is considerably more flexible than a standard speed limiter installed on a heavy goods vehicle where the limit is pre-set to a single value that remains the same regardless of the legal speed limit and cannot be changed by the driver.

The speed limit information provider may comprise a GPS receiver and map information.

The GPS receiver identifies the location of the vehicle and the map information includes information about the speed limit on the various types of roads. This information is available without any time delay.

The speed limit information provider may further comprise a camera and a system for processing data from the camera to identify traffic signs. The addition of a camera and a system for identifying traffic signs allows the system to respond to changes in the speed limits, for example those caused by road works, heavy spray or fog. It also addresses the problems caused by motorways such as the UK's M25 which has variable speed limits which are in place only at certain, undefined, times of the day or week. These speed limits are indicated only on the overhead gantries.

The speed limit information provider may further comprise a system for combining the GPS and map information with the traffic sign information derived from the camera. The most robust system is provided by a combination of traffic sign recognition with GPS and map data.

The vehicle may provided with an accelerator pedal to control the acceleration of the vehicle and the speed limiter may configured to disregard input from the accelerator pedal that would result in the vehicle speed exceeding the speed accepted by the driver using the SET button. By ignoring or disregarding the input from the accelerator that would otherwise result in the speed of the vehicle exceeding the speed accepted by the driver using the SET button, the brakes do not have to be used to reduce the speed of the vehicle. This is advantageous, especially for motorway driving where unnecessary use of the brakes can result in long tail backs. This feature also ensures a smooth ride experience as that vehicle speed is not constantly oscillating as a result of alternating brake and accelerator activity.

The system may be configured to shut down automatically if the accelerator pedal is fully depressed. If the accelerator pedal is fully depressed to provide a high percentage, typically 85%-100% throttle, the system is automatically shut down. This ensures that the driver can respond to an emergency situation without having to cancel the system manually. In a difficult situation nothing should distract the driver's attention from the road and therefore the automatic shut down feature provides an additional safety factor.

Furthermore, according to the present invention there is provided a method of limiting the speed of a vehicle, the method including the steps of: calculating the current speed limit; displaying the current speed limit to the driver, responding to a driver command to activate a speed limiter to limit the maximum speed of the vehicle to the current speed limit.

The present invention will now be described, by way of example only, with reference to the accompanying drawings.

Figures Ia to ic show a display that forms part of a Human Machine Interface (HMI) according to the present invention, Figure 2 shows a switch module that forms part of the HMI according to the present invention, Figure 3 shows the system architecture of an adaptive speed limiter system according to the present invention; Figure 4 is a graphical representation of the speed profile of a vehicle when using the system shown in Figure 3, and Figure 5 is an operation flow for the speed limiter system shown in Figure 3.

Figures la to Ic show a display 10 that forms part of an HMI 10, 20. Figure Ia shows to complete display 10. The display 10 comprises a speed limit information area 12 in the right side of the display 10. The speed limit is shown in figures presented in the style and colour of a typical speed limit sign. For example, in Great Britain the number is shown in black or dark figures and is surrounded by a red circle.

If the speed limit is exceeded, the display 10 is configured to show the speed limit in red text. In addition, or in the alternative, the text may flash. These changes indicate to the driver that the vehicle is currently exceeding the speed limit indicated. For example, if the speed limit is 50km/h, when the vehicle is travelling at 54km/h, the speed limit information will show 50km/h and the text will either be red or flashing or both in order to indicate that the speed limit is being exceeded and to make the driver aware of the speed limit.

The display 10 also has an area 14 in which the status of adaptive speed limiter system is shown. This part of the display incorporates an icon 16 that the driver will recognise as relating to a speed related driving aid. This part of the display 10 also includes an indication 18 of the current speed to which the adaptive speed limiter 30 is set. The status of the adaptive speed limiter system 30 as inactive, set or active is indicated using colour (not shown).

Area 14 in Figure la shows the configuration when the speed limiter system is not set.

The indication 18 of the current speed limit is replaced with a dash in this case. This part of the display 10 can be illuminated in different colours in order to communicate quickly with the driver the current status of the speed limiter system. When the system is inactive, either because it has not been set or because the driver has overridden the system, the icon 16 and the indication 18 of the status are either not illuminated or are illuminated in white.

Figure lb shows the area 14 of the display 10 as it would be seen when the speed limiter is set or active. When the speed limiter is either set or active the speed limit to which it is set is shown. If the speed limiter is set, but the vehicle is driving below the speed limit, this part of the display 10 is illuminated in green. lithe driver tries to accelerate gently through the speed limit and the speed limiter system has to be activated in order to prevent the vehicle from exceeding the speed limit, the content of the display does not change, but the colour is changed to orange in order to warn the driver that, were the system not in place, the current driving behaviour would result in the vehicle exceeding the speed limit.

Figure ic shows the area 14 of the display 10 as it would be seen when the speed limiter is set, but the speed limit is being exceeded. The speed limit is shown in orange, and is flashing to show that the current speed of the vehicle is in excess of the speed limit.

The HMI 10, 20 also includes an audible warning system (not shown). The audible warning system is activated when the speed of the vehicle exceeds the speed shown in the speed limit information area 12 of the display 10. This part of the system can operate independently from the speed limiter. Therefore, if the speed limiter has not been set the audible warning system will activate at any time that the driver exceeds the speed limit.

When the audible warning system is used in combination with the speed limiter the audible warning system can be useful as it alerts the driver that he has entered an area with a lower speed limit. Once the driver is aware of this fact, he can set the speed limiter to the new, lower speed limit and the system will then ensure that the speed limit is not exceeded.

Figure 2 shows a switching module 20 that forms part of the HMI 10, 20. The switching module 20 is configured to be mounted on the steering wheel of the vehicle so that the driver can access the module 20 without removing has hand from the steering wheel.

The switching module 20 has a SET button 22. The SET button 22 is configured to allow the driver, at a single button press, to accept a new maximum speed.

The SET button 22 can be pressed when the speed limiter system is inactive in order to activate the system and set the maximum speed to be the speed limit for the road at the time. The SET button 22 can also be pressed when the vehicle moves across a boundary between two speed limit regimes. The speed limit information area 12 of the display 10 will show that a new speed limit is in place and a single press of the SET button 22 cancels the previous regime and sets the new maximum speed to be the new speed limit.

There is a CANCEL button 24 which can be pressed if the driver wishes to cancel the activity of the speed limiter system as a whole. There is no need to press this button in order to cancel a particular speed regime. Changing from one speed regime to another requires only the SET button 22.

There is also a rocker switch 26 which can be rocked downwards to reduce the speed at which the speed limiter is set. The rocker switch can be rocked upwards in order to increase the speed at which the speed limiter is set.

Figure 3 shows the system architecture of an adaptive speed limiter system 30. The adaptive speed limiter system 30 includes a speed limit information provider 40, an HMI 10, 20, and a speed limiter 50.

The speed limit information provider 40 includes a GPS receiver 41, a memory 42 for storing map data; a camera 43, a system 44 for detecting and recognising traffic signs from the camera data, a system 45 for combining the data from the GPS receiver with the stored map data stored in the memory 42 and a system 46 for combining the output of the system 45 with the traffic sign data provided by system 44 and disambiguating the combined data.

The GPS receiver 4lis used to identify the location of the vehicle and this information is combined with the map data in order to identify on which road the vehicle is travelling.

The map data includes data about the speed limit of the roads. This information is quite basic and, in the simplest example, consists only of information about the speed limit on the various types of roads. Some local authorities have amended the speed limit in certain areas in an attempt to increase the safety on certain roads. In some cases this information is included with the map data. The system 45 combines the GPS information with the map information in order to identify the location of the vehicle and provide initial information regarding the relevant speed limit.

The camera 43 is mounted forward facing, relative to the normal direction of motion of the vehicle. The camera 43 captures images of the road ahead of the vehicle and the immediate area around the road. For example, the camera 43 is mounted so that road side signs and overhead gantries on motorways fall within the field of view. The camera 43 relays images to the system 44 for detecting and recognising traffic signs. The system 44 processes the data from the camera 43 and identifies speed signs.

The initial information regarding the speed limit provided by system 45 relying on the GPS and map data is combined with the traffic sign information output from the system 44 in the system 46 which is configured to disambiguate the data. The resulting speed limit information is output by the speed limit information provider 40 for use in the speed limiter system 30.

In an alternative example, not shown in the accompanying figures, a rain sensor on the vehicle acts as a further input to the speed limit information provider 40. Some roads have speed limits that change with the road conditions. By adding an input to the speed limit information provider from a rain sensor, the disambiguation system 46 can use information from the rain sensor to identify which speed limit should apply in cases where the map data indicates that there is a wet weather speed limit and a dry weather limit.

In a further alternative example, not shown in the accompanying drawings, the camera 43 and a system 44 for detecting and recognising traffic signs from the camera data may be augmented or replaced by a receiver configured to receive information transmitted by individual traffic signs. Alternatively, the receiver may be configured to receive live updates regarding speed limits that may be sent out by a central computer system.

The speed limiter 50 is provided within or connected to the engine management system.

The limiter 50 is connected to the switching module 20 of the HMI via the Engine Control Unit (ECU) as described above with reference to Figures 1 and 2. When the SET button 22 is pressed in order to activate the system or set a new maximum speed, this information is transmitted from the switching module 20 to the speed limiter 50. The speed limiter 50 is configured to ensure that as the speed does not exceed the maximum speed set using the switching module 20 of the HMI.

The speed limiter 50 operates to "ignore" or disregard any input from the accelerator pedal 55 that would result in the vehicle speed increasing above the speed limit. In this example the speed limiter 50 does not apply the brakes.

The adaptive speed limiter system 30 takes the real-time information provided by the speed limit information provider 40 and presents any changes to the driver on the display 10 of the HMI. The driver can choose to react to this change to the speed limit by pressing the SET button 22 and thereby setting a new value for the speed limiter 50.

The speed limiter 50 prevents the vehicle speed from exceeding the speed limit that has been set using the SET button 22.

In a vehicle that has not been fitted with the system, the combi-meter receives the speed signal and makes corrections that take into account the legal requirement that a speedometer must never under-read. The newly calculated speed is then displayed to the driver on the speedometer. As a result of inaccuracies in reading the actual road speed and further changes to the speed taking place in the calculation phase, the speed displayed on the speedometer is always a conservative representation of the actual road speed of the vehicle.

In a vehicle which is fitted with the adaptive speed limiter system 30, the ECU is configured such that, when the driver presses the SET button 22 to accept the speed of, for example, 30mph, the ECU reverses the usual calculation performed by the combi-meter and sets the maximum speed to that speed, typically around 27mph, which will result in the speedometer indicating that the vehicle is travelling at 30mph.

Figure 4 is a diagram showing the speed profile of a vehicle using an adaptive speed limiter system 30. The dashed line shows the speed limit. The solid line shows the speed of the vehicle. The dash-dot line shows the speed profile that a vehicle would have without the adaptive speed limiter system 30. Prior to point A on Figure 4 the vehicle is proceeding along a dual carriageway or motorway with a 70mph speed limit.

At point A the driver notices a change of speed limit to 60mph and begins to decelerate down towards 60mph.

At point B the vehicle passes from the 70mph zone into the 60mph zone and the display of the adaptive speed limiter system 30 displays 60mph as the new speed limit.

Using the SET button 22 of the switch module 20, the driver accepts the new maximum speed of 60mph. If the driver accepts the new limit before the vehicle's speed has descended to 60mph, the speed limiter 14 display will be orange and flashing in order to show that the system is active but that the currently set speed is being exceeded. In addition, the speed limit information area 12 of the display 10 will show 60mph as the speed limit and this will flash to make the driver aware that he is currently exceeding the new speed limit.

During the area noted as C, the driver chooses to decelerate below the new speed limit of 60mph, possibly as a result of the road conditions. He continues to use the brake to reduce the speed of the vehicle. This does not affect the status of the adaptive speed limiter 30 which remains set at 60mph. During this period the lighting on the area 14 of the display 10 will be illuminated in green to show that, although the adaptive speed limiter 30 is set, it is not actively limiting the speed of the vehicle at this time.

In the area marked D, the adaptive speed limiter 30 is initially set, but not active and the area 14 of the display will be illuminated in green to show that the system is set, but it is not actively limiting the speed of the vehicle. As the driver continues to depress the accelerator pedal so that, if the system were not active, the speed would increase to 61mph, the area 14 of the display will be illuminated in orange to warn the driver that, if the system 30 were not active then the current behaviour with regard to the accelerator pedal would result in the speed limit being exceeded. The speed of the vehicle based solely on the driver's behaviour is shown in the dash-dot line.

At point E the speed limit changes from 60mph to 30mph. This change will be shown on the display 10 and the driver will be prompted to set a new maximum speed by pressing the SET button 22. During the zone F the driver controls the deceleration of the vehicle from 60mph to 30mph. As soon as the vehicle passes the 30mph sign, the speed limit information area 12 of the display will show the new speed limit of 30mph and this part of the display will flash to show that the driver is exceeding this speed. In addition, if the audible warning system is not disabled, it will become active to warn the driver in an audible manner that he is exceeding the new speed limit. The driver presses the SET button 32 so that, as soon as he has controlled the deceleration of the vehicle down to mph, the system will prevent the vehicle exceeding this speed.

Zone G shows the vehicle speed as the driver manoeuvres the vehicle through the urban environment, responding to the presence of parked vehicles and more vulnerable road users by driving at a speed appropriate to the road conditions. In zone H the adaptive speed limiter 30 is active and prevents the vehicle from exceeding the speed limit. The projected speed of the vehicle, if the adaptive speed limiter 30 was not active is shown in the dash-dot line.

At point I the driver identifies a hazard that causes him to brake sharply and then, shortly afterwards, at point J, to apply 100% throttle and accelerate rapidly. During the deceleration the adaptive speed limiter 30 remains set although not active. However, when 100% throttle is applied, the adaptive speed limiter 30 is cancelled and the vehicle accelerates through the speed limit. By cancelling the system under extreme conditions, the driver's ability to react to unforeseen hazards is not compromised.

The behaviour of the adaptive speed limiter system 30 is set out in detail in Figure 5.

Once the engine has been started, the system can be switched on. If the system is not switched on then nothing will be displayed on the display 10, the audible warning system be inactive and the speed limit will also remain totally inactive. The provision of an overall on/off switch provides an additional safety feature. It also allows a driver to choose whether or not to use the system. In addition, the system may be configured so that the audible warning system is not active even when the remainder of the system is active.

If the system is switched on, but the SET button 22 is not pressed, the system is in a waiting condition. During this time the speed limit information area 12 of the display 10 is active and shows the speed limit that is applicable to the road on which the vehicle is travelling. In addition, in the example in which an audible warning is provided, the audible warning informs the driver when the speed limit is being exceeded.

In order to use the full capability of the system, the SET button 22 is pressed. This accepts the speed limit displayed in area 12 of the display 10 as the maximum speed of the vehicle.

At any time when the SET button 22 has been pressed and the system is set, if the driver fully depressed the throttle, using for example 85% throttle or above, then the system will be automatically disabled so that the driver's ability to accelerate sharply in order to avoid a hazard is not compromised.

Furthermore, the driver can at any time press the CANCEL button 24 in order to disable the system. In addition, the driver can use the rocker switch 26 in order to make incremental changes to the set speed.

If, at any time when the system is set, the current speed of the vehicle exceeds the set speed, the accelerator pedal will be ignored until the driver has reduced the velocity of the vehicle of his own volition. This can be achieved either by coasting or by applying the brakes.

When the current speed of the vehicle is equal to the set speed, the speed limiter part 14 of the display 10 will change to green. The driver is then able to accelerate and decelerate in response to road conditions provided that the vehicle's speed would not exceed the set speed. If the driver presses the accelerator so that, in the absence of the system, the set speed would be exceeded, the speed limiter ignores the input from the accelerator and the vehicle does not accelerate.

It will also be apparent from the flow diagram as a whole, that if there is any difficulty, such as a lack of reliable speed limit information, then the system is disabled.

As there is no automatic acceleration because the driver is permitted to drive responsively up to the speed limit, there is no need to monitor the clutch status.

Claims

1. A human machine interlace (HMI) for an adaptive speed limiter, the HMI comprising: a display configured to communicate to the driver the current speed limit, and an indication that the current speed limit is being exceeded, and a switch module including a SET button configured to permit the driver to set the maximum speed of the vehicle to the speed limit.

2. The HMI according to claim 1, wherein the switch module further comprises a rocker switch to allow the maximum speed to be altered.

3. The HMI according to claim 1 or claim 2, wherein the display further comprises an indication as to the status of adaptive speed limiter system.

4. The HMI according to any one of the preceding claims, wherein the display further comprises an indication of the value of the speed limit that is currently set in the adaptive speed limiter.

5. The HMI according to any one of the preceding claims, further comprising an audible warning system configured to be activated when the speed of the vehicle exceeds the speed to which the adaptive speed limiter is set.

6. An adaptive speed limiter system for use in a vehicle, the adaptive speed limiter system comprising: a speed limit information provider; an HMI according to any one of the preceding claims; wherein the display of the HMI is configured to display the speed limit information provided by the speed limit information provider, and a speed limiter connected to the switch module of the HMI and configured to limit the maximum speed of the vehicle to the speed accepted by the driver using the SET button.

7. The system according to claim 6, wherein the speed limit information provider comprises a GPS receiver and map information.

8. The system according to claim 7, wherein the speed limit information provider further comprises a camera and a system for processing data from the camera to identify traffic signs.

9. The system according to claim 7, wherein the speed limit information provider further comprises a system for combining the GPS and map information with the traffic sign information derived from the camera.

10. The system according to any one of the preceding claims, wherein the vehicle is provided with an accelerator pedal to control the acceleration of the vehicle and wherein the speed limiter is configured to disregard input from the accelerator pedal that would result in the vehicle speed exceeding the speed accepted by the driver using the SET button.

11. The system according to claim 10, wherein the system is configured to shut down automatically if the accelerator pedal is fully depressed.

12. A method of limiting the speed of a vehicle, the method including the steps of: calculating the current speed limit; displaying the current speed limit to the driver, responding to a driver command to activate a speed limiter to limit the maximum speed of the vehicle to the current speed limit.