AUTOMATIC SPEED CONTROL FOR A VEHICLE

Abstract

Aspects of the present invention relate to an automatic speed control system, a method (200) for automatically controlling the speed of a vehicle, and a vehicle comprising the system or for carrying out the method. The system and method obtains (202) an initial speed limit, wherein the initial speed limit is the speed limit at a location of the vehicle, receives (204) a signal identifying a speed limit offset; and sets (206) the speed of the vehicle to the initial speed limit combined with the offset. The system and method may obtain (208) an updated speed limit and set (210) the speed of the vehicle to the updated speed limit. The system and method may obtain (212) a further speed limit; and if at least one criterion is met (214), set (216) the speed of the vehicle to the further speed limit combined with the offset.

Claims

1. An automatic speed control system for a vehicle, the automatic speed control system comprising one or more controllers, the automatic speed control system configured to: obtain an initial speed limit, wherein the initial speed limit is the speed limit at a location of the vehicle; receive a signal identifying a speed limit offset; set the speed of the vehicle to the initial speed limit combined with the offset; obtain an updated speed limit; set the speed of the vehicle to the updated speed limit; and subsequently, obtain a further speed limit; and if at least one criterion is met, set the speed of the vehicle to the further speed limit combined with the offset.

2. The automatic speed control system as claimed in claim 1, wherein the one or more controllers comprise: speed limit obtaining means to obtain the speed limit at the location of the vehicle; input means to receive the signal; speed adjusting means to adjust the speed of the vehicle to the speed limit combined with the offset, in response to the signal, and after a change in speed limit where the at least one criterion is met; and speed limit analysing means to analyse the speed limit for at least one change thereto and to analyse an updated speed limit in relation to the at least one criterion.

3. The automatic speed control system as claimed in claim 1, wherein the at least one criterion relates to a comparison of the initial speed limit and the further speed limit; optionally, the at least one criterion is that the initial speed limit is equal to the further speed limit.

4. The automatic speed control system as claimed in claim 1, wherein the at least one criterion relates to the distance for which the updated speed limit was applicable; optionally, the at least one criterion specifies that the distance for which the updated speed limit was applicable must be below a distance threshold; optionally, the distance threshold is adjustable by the user.

5. The automatic speed control system as claimed in claim 1, wherein the at least one criterion relates to the magnitude of the offset; optionally, the at least one criterion includes that the magnitude of the offset is less than a threshold value.

6. The automatic speed control system as claimed in claim 1 configured to receive a signal to adjust the updated speed of the vehicle by a second offset.

7. A method for automatically controlling the speed of a vehicle, comprising: obtaining an initial speed limit, wherein the initial speed limit is the speed limit at a location of the vehicle; receiving a signal to adjust the speed of the vehicle by an offset; setting the speed of the vehicle to the initial speed limit combined with the offset; obtaining an updated speed limit; setting the speed of the vehicle to the updated speed limit; and subsequently, obtaining a further speed limit; and if at least one criterion is met, setting the speed of the vehicle to the further speed limit combined with the offset.

8. The method as claimed in claim 7, wherein the at least one criterion relates to a comparison of the initial speed limit and the further speed limit.

9. The method as claimed in claim 8, wherein the at least one criterion is that the initial speed limit is equal to the further speed limit.

10. The method as claimed in any claim 7, wherein the at least one criterion relates to the distance for which the updated speed limit was applicable; optionally, the at least one criterion specifies that the distance for which the updated speed limit was applicable must be below a distance threshold.

11. The method as claimed in claim 7, wherein the at least one criterion relates to the magnitude of the offset.

12. The method as claimed in claim 11, wherein the at least one criterion includes that the magnitude of the offset is less than a threshold value.

13. A non-transitory computer readable medium comprising computer readable instructions that, when executed by a processor, cause performance of the method of claim 7.

14. A vehicle comprising an automatic speed control system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0027] FIG. 1 shows a block diagram illustrating an embodiment of the invention;

[0028] FIG. 2 shows a flow diagram illustrating an embodiment of the invention;

[0029] FIG. 3(a) shows a block diagram illustrating one step of the embodiment of the invention shown in FIG. 2;

[0030] FIG. 3(b) shows a block diagram illustrating an alternative to the step shown in FIG. 3(a);

[0031] FIG. 4 shows a further flow diagram illustrating an embodiment of the invention;

[0032] FIG. 5 shows another flow diagram illustrating an embodiment of the invention;

[0033] FIG. 6 shows a further block diagram illustrating an embodiment of the invention;

[0034] FIG. 7(a) shows a diagram illustrating a first example of an embodiment of the invention;

[0035] FIG. 7(b) shows a diagram illustrating a second example of an embodiment of the invention; and

[0036] FIG. 8 shows a vehicle in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

[0037] The present invention relates to an automatic speed control system, a method for automatically controlling the speed of a vehicle, and a vehicle. The automatic speed control system may form part of, or may be separate but complimentary to, an adaptive cruise control (ACC) system in a vehicle. An ACC system adapts the vehicle's speed to the vehicle's environment, for example the presence and speed of another vehicle ahead of the vehicle in question, or the speed limit in force at the vehicle's location.

[0038] An ACC system that is adapted to control a vehicle's speed based on the applicable speed limit may allow a user to set an offset to be applied to the speed limit when setting the vehicle's speed. The user may apply an offset above or below the speed limit. The user may apply an offset within a certain threshold of the speed limit. In this way, the ACC system will not allow the user to set a vehicle speed significantly higher or lower than the speed limit.

[0039] With reference to FIG. 1, there is shown an automatic speed control system 100 for a vehicle. The automatic speed control system 100 comprises speed limit obtaining means 102, input means 104, speed adjusting means 106, and speed limit analysing means 108. The speed limit obtaining means 102 obtain the speed limit at the location of the vehicle. The input means 104 receive a signal identifying a speed limit offset. The speed adjusting means 106 adjust the speed of the vehicle to the speed limit combined with the offset, in response to the signal. The speed adjusting means 106 also adjust the speed of the vehicle to the speed limit combined with the offset after a change in speed limit where the at least one criterion is met. The speed limit analysing means 108 analyse the speed limit for a change thereto and analyse the changed speed limit in relation to at least one criterion.

[0040] The speed limit obtaining means 102, input means 104, speed limit analysing means 108, and speed adjusting means 106 may be implemented by one or more controllers. The one or more controllers may be implemented by a processor. The one or more controllers may be configured to obtain an initial speed limit, wherein the initial speed limit is the speed limit at a location of the vehicle. The one or more controllers may be configured to receive a signal identifying a speed limit offset. The one or more controllers may be configured to set the speed of the vehicle to the initial speed limit combined with the offset. The one or more controllers may be configured to obtain an updated speed limit. The one or more controllers may be configured to set the speed of the vehicle to the updated speed limit. The one or more controllers may be configured to obtain a further speed limit; and if at least one criterion is met, set the speed of the vehicle to the further speed limit combined with the offset.

[0041] Referring to FIG. 2, there is shown a flowchart illustrating a method for automatically controlling the speed of a vehicle, indicated generally by the reference number 200, according to an embodiment of the invention. The method 200 begins at 202 by obtaining an initial speed limit, wherein the initial speed limit is the speed limit at a location of the vehicle. At 204, the method 200 comprises receiving a signal to adjust the speed of the vehicle by an offset. At 206, the method 200 comprises setting the speed of the vehicle to the initial speed limit combined with the offset. At 208, the method 200 comprises obtaining an updated speed limit. At 210, the method 200 comprises setting the speed of the vehicle to the updated speed limit. The updated speed limit may be referred to as a temporary speed limit or an interim speed limit. At 212, the method comprises obtaining a further speed limit. At 214, the method comprises checking for a criterion. In 216, the method 200 comprises setting the speed of the vehicle to the further speed limit combined with the offset, if the criterion has been met.

[0042] The automatic speed control system 100 may obtain the speed limit for the location of the vehicle in a number of ways. In a first example, systems on board the vehicle in question may capture an image of the speed limit signage for the location of the vehicle, and carry out image processing on the images to identify the speed limit illustrated in the signage. In another example, the speed limit for the location may be received from a remote transmitter, may be obtained from a navigation system, or may be looked-up based on a GPS-indication of the vehicle's location. The automatic speed control system 100 may obtain the speed limit for the location of the vehicle according to known methods used in adapted cruise control systems, and will not be discussed further herein.

[0043] The automatic speed control system 100 may receive the signal indicating the desired offset via a user interface of the vehicle. Such a user interface may include a voice interface, touchscreen, gesture recognition, a keypad or other arrangement of keys or buttons, and the like.

[0044] Once the desired offset has been obtained, the automatic speed control system 100 controls the speed of the vehicle to be that of the speed limit combined with the offset. For example, if the speed limit was 80 kmph, with an offset of +5 kmph, the automatic speed control system 100 would control the speed of the vehicle to be 85 kmph. In a further example, if the speed limit was 120 kmph, and the offset was −10 kmph, the automatic speed control system 100 would control the speed of the vehicle to be 110 kmph. The automatic speed control system 100 may control the speed of the vehicle according to any suitable method, including those known methods used in cruise control and adapted cruise control systems, and will not be discussed further herein.

[0045] When the automatic speed control system 100 detects a change in the speed limit, the speed of the vehicle is adjusted accordingly. If the user wishes to apply the offset again, he or she must enter the desired offset again via the user interface.

[0046] In some circumstances, the change in speed limit may be temporary and the speed limit returns to the previous speed limit after a reasonably short distance. Such temporary speed limits may be due, for example, to a junction, roadworks, traffic calming measures or the like. It such cases the user must reapply the desired offset after this temporary speed limit change. This is inconvenient for the user. The present invention recognises certain circumstances wherein this user inconvenience can be avoided.

[0047] Referring now to FIG. 3(a), there is shown a block diagram of factors that may be considered when checking the criterion at 214 in the method 200 shown in FIG. 2. These circumstances may relate to the relationship between the initial speed limit at which the offset was applied, and the further speed limit after the interim speed limit. The circumstances may relate to the distance for which the interim speed limit was applicable. FIG. 3(a) shows in an embodiment, that the criterion checking block 214 of method 200 comprises, at 217, comparing the initial speed limit with the further speed limit; and at 218, determining the distance for which the interim speed limit was applicable. One criterion for re-implementing the previous offset, according to block 216 of the method 200, may be that the initial speed limit and the further speed limit are equal. Another criterion may be that the distance for which the updated speed limit was applicable is below a distance threshold. The distance threshold may be between 80 metres and 120 metres, and in an example, the distance threshold is 100 metres. The distance threshold may be configurable, at initialisation of the system, and/or by the user

[0048] Referring now to FIG. 3(b), there is shown an alternative block diagram of factors that may be considered when checking the criterion at 214 in the method 200 shown in FIG. 2. These circumstances may further relate to the magnitude of the offset. FIG. 3(b) shows in an embodiment, that the criterion checking block 214 of the method 200 shown in FIG. 2 additionally comprises, at 219, comparing the magnitude of the offset with a threshold. The offset threshold value may be between 8 kilometres per hour and 12 kilometres per hour. In an example, the threshold value may be 10 kilometres per hour.

[0049] Referring to FIG. 4, there is shown a flowchart illustrating a method, indicated generally by the reference numeral 400, according to an embodiment of the invention. The method 400 comprises, at 402, monitoring the speed limit for the location of the vehicle to detect a change in the speed limit. As discussed above, there are a number of known methods to derive the speed limit for the present location of that vehicle. If a change in speed limit is detected, the method 400 analyses, at 404, the distance since the last change in speed limit. If the distance since the last change in speed limit is greater than or equal to a distance threshold, the method 400 sets, at 406, the speed of the vehicle to the speed limit.

[0050] If the distance since the last change in speed limit is less than a distance threshold, the method 400 compares, at 408, the current speed limit to the last-but-one speed limit. That is, if the current speed limit is the nth speed limit encountered on this journey, then the nth speed limit is compared to the (n−2)th speed limit. If the current speed limit is not equal to the last-but-one speed limit, then the method 400 proceeds again to block 406 to set the speed of the vehicle to the speed limit. If however, the current speed limit is equal to the last-but-one speed limit, then method 400 sets, at 410, the speed of the vehicle to the speed limit adjusted by any offset that had been applied to the speed of the vehicle at the last-but-one speed limit.

[0051] Referring to FIG. 5, there is shown a flowchart illustrating a method, indicated generally by the reference numeral 450, according to an embodiment of the invention. The method 450 of FIG. 5 is substantially similar to the method 400 shown in FIG. 4 except that the method 450 of FIG. 5 comprises an additional step. After the method 450 has compared the new speed limit to the last-but-one speed limit, the method checks, at 452, if the magnitude of any offset that had been applied to the last-but-one speed limit is below a threshold value. If the offset is less than the threshold value, then method 400 sets, at 410, the speed of the vehicle to the speed limit adjusted by that offset that had been applied to the speed of the vehicle at the last-but-one speed limit. If however, the offset is greater than or equal to the threshold value, the method 400 sets, at 406, the speed of the vehicle to the speed limit.

[0052] It will be understood that the methods 400, 450 described herein in relation to FIGS. 4 and 5 are not limited as to the order in which the different criteria are checked. For example, checking the distance travelled since the last change in speed limit may be checked after the speed limits are compared, and so on.

[0053] The methods for automatically controlling the speed of a vehicle described herein in relation to FIG. 2, 3, 4 or 5 may be carried out by the automatic speed control system 100.

[0054] In a further embodiment, the automatic speed control system 100 may receive a further signal during the interim speed limit, wherein the further signal is indicative of a second offset to be applied to the interim speed limit.

[0055] Referring to FIG. 6, there is shown a schematic of an example machine-readable medium 502 with a processor 505. The machine-readable medium 502 may comprise instructions which, when executed by a processor 505, cause the processor to perform the method 200 discussed above in relation to FIGS. 2 and 3. The machine-readable medium 502 may comprise instructions which, when executed by a processor 505, cause the processor to obtain the speed limit at the location of the vehicle. The machine-readable medium 502 may comprise speed limit obtaining instructions 506 to perform the obtaining. The machine-readable medium 502 may comprise instructions which, when executed by a processor 505, cause the processor to receive an input indicating the speed limit offset to be applied. The machine-readable instructions may comprise offset receiving instructions 508 to perform the receiving.

[0056] The machine-readable medium 502 may comprise instructions which, when executed by a processor 505, cause the processor to, set the speed of the vehicle. The machine-readable medium 502 may comprise speed setting instructions 510 to set the vehicle speed.

[0057] The machine-readable medium 502 may comprise instructions which, when executed by a processor 505, cause the processor to check for a criterion. The machine-readable medium 505 may comprise criterion checking instructions 512 to check for the criterion.

[0058] In some examples, the machine-readable medium 502 may comprise additional instructions which, when executed by a processor 505, cause the processor to perform alternative or additional actions in line with the methods and examples described herein.

[0059] The machine-readable instructions may, for example, be executed by a general purpose computer, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams. In particular, a processor or processing apparatus may execute the machine-readable instructions. Thus, functional modules of the apparatus and devices may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry. The term ‘processor’ is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate array etc. The methods and functional modules may all be performed by a single processor or divided amongst several processors.

[0060] Referring to FIGS. 7(a) and 7(b), there is shown timing diagrams illustrating examples according to embodiments of the invention. In the FIG. 7(a), there is shown two examples where the updated speed limit is lower than the initial speed limit. In the upper diagram of FIG. 7(a), the speed set by the automatic speed control system 100 is indicated by the line 702. The speed limit is 50 kmph. At the start of the diagram, the vehicle speed is set to the speed limit. Then at 704, an offset is applied and the vehicle speed is increased to (50+offset) kmph. At 706, an upcoming reduced speed limit is detected, and the vehicle speed is reduced to the reduced speed limit of 30 kmph. At 708, the updated speed limit comes into effect and continues until 710. The vehicle speed is set to the updated speed limit between 708 and 710. The physical distance between 708 and 710 is less than a threshold distance. At 710, the speed limit returns to 50 kmph. Therefore, as the distance at which the updated speed limit was applicable is less than the threshold value and the further speed limit is equal to the initial speed limit, the previous offset is reapplied to the speed limit such that the vehicle speed is set to (50+offset) kmph. In the lower diagram of FIG. 7(a), the speed set by the automatic speed control system 100 is indicated by the line 712. The early stages 704, 706, 708 of the example are the same as those of the upper example. In the lower diagram of FIG. 7(a), the updated speed limit ends at 714, which is further away from 708 than 710 in the upper example. This leads to the distance at which the updated speed limit is applicable being greater than the threshold. Thus when the further speed limit is applicable at 714, the offset is not reapplied and the vehicle speed is set to 50 kmph.

[0061] In the FIG. 7(b), there is shown two examples where the updated speed limit is higher than the initial speed limit. In the upper diagram of FIG. 7(b), the speed set by the automatic speed control system 100 is indicated by the line 720. The speed limit is 50 kmph. At the start of the diagram, the vehicle speed is set to the speed limit. Then at 704, an offset is applied and the vehicle speed is increased to (50+offset) kmph. At 722, an increased speed limit is detected, and the vehicle speed is adjusted to the increased speed limit of 70 kmph. The updated speed limit continues until 724. The vehicle speed is set to the updated speed limit between 722 and 724. The physical distance between 722 and 724 is less than a threshold distance. At 724, the speed limit returns to 50 kmph. Therefore, as the distance at which the updated speed limit was applicable is less than the threshold value and the further speed limit is equal to the initial speed limit, the previous offset is reapplied to the speed limit such that the vehicle speed is set to (50+offset) kmph. In the lower diagram of FIG. 7(b), it can be seen that an offset is already applied. The updated speed limit ends at 726, which is further away from 722 than 724, and the distance at which the updated speed limit is applicable is greater than the threshold. Thus when the further speed limit is applicable at 726, the offset is not reapplied and the vehicle speed is set to 50 kmph.

[0062] Referring to FIG. 8, there is shown a vehicle in accordance with an embodiment of the present invention, the vehicle being indicated generally by the reference numeral 800. The vehicle 800 may comprise the automatic speed control system described herein, and/or may be adapted to implement one or more of the methods for automatically controlling the speed of the vehicle.

[0063] Throughout the specification, the updated speed limit may be referred to as the temporary speed limit or interim speed limit. The initial speed limit may be referred to as the last-but-one or (n−2)th speed limit. The further speed limit may be referred to as the nth speed limit.

[0064] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.