A CONTROL DEVICE AND A METHOD FOR CONTROLLING VEHICLE SPEED

Abstract

A method and a control device for controlling speed of a vehicle having an automatic cruise control system configured to automatically control speed based on a set speed and to automatically reduce the speed to a predetermined safe speed below the set speed as it is detected that the vehicle approaches a road section of a predetermined type such as a curve. The method includes while automatically controlling the speed towards the predetermined safe speed as the vehicle approaches the road section of the predetermined type, receiving a request from a driver of the vehicle to control speed to a temporary speed different from the predetermined safe speed and the set speed. The method includes in response to said request, controlling the speed to the temporary speed. The method includes at an end of the road section of the predetermined type, automatically controlling the speed based on the set speed.

Claims

1. A control device for controlling a vehicle speed of a vehicle, wherein the control device is configured to automatically control the vehicle speed based on a set speed (v.sub.set) and to automatically reduce the vehicle speed to a predetermined safe speed (v.sub.safe) below the set speed as it is detected that the vehicle approaches a road section of a predetermined type, wherein the control device is configured to: while automatically controlling the vehicle speed towards the predetermined safe speed (v.sub.safe) as the vehicle approaches the road section of the predetermined type, receive a request from a driver of the vehicle to control the vehicle speed to a temporary vehicle speed (v.sub.temp) different from the predetermined safe speed (v.sub.safe) and the set speed (v.sub.set), wherein the temporary vehicle speed is set by the driver; in response to said request and without disabling of the control device, control the vehicle speed to the temporary vehicle speed (v.sub.temp), and at an end of the road section of the predetermined type, automatically control the vehicle speed based on the set speed (v.sub.set), wherein the predetermined type of road section is a curve.

2. The control device according to claim 1, wherein the control device is configured to identify at least a first type of request from the driver and in response thereto set the temporary vehicle speed (v.sub.temp) to a current vehicle speed of the vehicle at a time of receiving the first type of request.

3. The control device according to claim 2, wherein the control device is further configured to identify a second type of request from the driver and in response thereto reduce the vehicle speed below the predetermined safe speed (v.sub.safe).

4. The control device according to claim 3, wherein the control device is configured to reduce the vehicle speed until a predetermined end condition is fulfilled.

5. The control device according to claim 4, wherein said predetermined end condition is considered to be fulfilled when the first type of request is received, or when it is determined that the vehicle has reached the end of the road section of the predetermined type.

6. The control device according to claim 2, wherein the control device is configured to identify the request from the driver as the first type of request when said request is generated by actuating an accelerator pedal of the vehicle.

7. The control device according to claim 3, wherein the control device is configured to identify the request from the driver as the second type of request when said request is generated by actuating a brake pedal of the vehicle.

8. The control device according to claim 1, wherein the control device is configured to store data relating to the request from the driver.

9. The control device according to claim 8, wherein the control device is configured to use the stored data for adaptation of the predetermined safe speed (v.sub.safe) of the vehicle.

10. The control device according to claim 8, wherein the control device is further configured to: detect that the vehicle approaches a previously travelled road section of the predetermined type for which data relating to at least one request from the driver has been stored, and in response to said detection, automatically control the vehicle speed to a stored temporary vehicle speed.

11. A vehicle comprising a control device according to claim 1.

12. A method for controlling a vehicle speed of a vehicle having an automatic cruise control system configured to automatically control the vehicle speed based on a set speed (v.sub.set) and to automatically reduce the vehicle speed to a predetermined safe speed (v.sub.safe) below the set speed (v.sub.set) as it is detected that the vehicle approaches a road section of a predetermined type, wherein the method comprises: while automatically controlling the vehicle speed towards the predetermined safe speed (v.sub.safe) as the vehicle approaches the road section of the predetermined type, receiving a request from a driver of the vehicle to control the vehicle speed to a temporary vehicle speed (v.sub.temp) different from the predetermined safe speed (v.sub.safe) and the set speed (v.sub.set), wherein the temporary vehicle speed is set by the driver, in response to said request and without disabling of the control device, controlling the vehicle speed to the temporary vehicle speed (v.sub.temp), and at an end of the road section of the predetermined type, automatically controlling the vehicle speed based on the set speed (v.sub.set), wherein the predetermined type of road section is a curve.

13. The method according to claim 12, further comprising identifying at least a first type of request from the driver, and in response thereto setting the temporary vehicle speed to a current vehicle speed of the vehicle at a time of receiving the first type of request.

14. The method according to claim 13, further comprising identifying a second type of request from the driver and in response thereto reducing the vehicle speed below the predetermined safe speed (v.sub.safe).

15. The method according to claim 14, further comprising reducing the vehicle speed until a predetermined end condition is fulfilled.

16. The method according to claim 15, wherein said predetermined end condition is considered to be fulfilled when the first type of request is received, or when it is determined that the vehicle has reached the end of the road section of the predetermined type.

17. The method according to claim 13, comprising identifying the request from the driver as the first type of request when said request is generated by actuating an accelerator pedal of the vehicle.

18. The method according to claim 14, comprising identifying the request from the driver as the second type of request when said request is generated by actuating a brake pedal of the vehicle.

19. The method according to claim 12, further comprising: storing data relating to said request from the driver.

20. The method according to claim 19, further comprising: using the stored data for adaptation of the predetermined safe speed (v.sub.safe) of the vehicle.

21. The method according to claim 19, further comprising: detecting that the vehicle approaches a previously travelled road section of the predetermined type for which data relating to at least one request from the driver has been stored, in response to said detection, automatically controlling the vehicle speed to a stored temporary vehicle speed.

22. (canceled)

23. A non-transitory computer readable medium carrying a computer program comprising program code for performing the steps of claim 12 when said computer program is run on a computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0056] In the drawings:

[0057] FIG. 1 shows a vehicle according to an embodiment of the invention,

[0058] FIG. 2 is a flow chart illustrating a method according to an embodiment of the invention,

[0059] FIG. 3a schematically shows a road on which a vehicle according to an embodiment of the invention is travelling,

[0060] FIG. 3b shows vehicle speed as a function of vehicle position on the road, and

[0061] FIG. 4 shows a control device according to an embodiment of the invention.

[0062] The drawings show diagrammatic exemplifying embodiments of the present invention and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the invention is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the invention. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0063] A vehicle 1 in the form of a heavy-duty truck is schematically shown in FIG. 1. The vehicle 1 includes a control device 10 for controlling a vehicle speed of a vehicle 1. In the shown embodiment, the control device 10 forms part of an automatic cruise control system configured to automatically control the vehicle speed v based on a set speed v.sub.set, which may be set by a driver of the vehicle 1 or which may be automatically set based on e.g. a speed limitation of a road on which the vehicle 1 travels. The vehicle 1 comprises an accelerator pedal 11 and a brake pedal 12, by means of which the driver may manually control the vehicle speed, and by means of which the driver may furthermore generate requests to the control device 10.

[0064] The vehicle 1 is furthermore equipped with various types of sensors (not shown), including one or more of: at least one wheel speed sensor for sensing rotational speed of a wheel of the vehicle, a steering angle sensor, an electronic accelerator pedal sensor, a brake pedal sensor, a local environment perception sensor such as a camera, a radar or a lidar, an inclination sensor for indicating vehicle inclination, an accelerometer, a temperature sensor, and sensors for sensing various engine parameters. The vehicle may also comprise a navigation system for determining a position of the vehicle and predict characteristics of a road on which the vehicle is travelling, e.g. based on map data in combination with positioning information, such as global positioning system (GPS) information.

[0065] The automatic cruise control system may be configured to control the vehicle speed based on one hand on the set speed v.sub.set, and on the other hand on e.g. road topography and surrounding traffic, using e.g. data received from the navigation system and/or from the sensors of the vehicle, such as from local environment perception sensors. Thus, the automatic cruise control system may be a cruise control system which automatically adapts the vehicle speed to keep a minimum safety distance to a vehicle travelling ahead of the vehicle, and which adjusts the vehicle speed to improve the energy efficiency of the vehicle 1 during driving.

[0066] A method according to an embodiment of the invention is illustrated in FIG. 2. The method may be carried out by the control device 10, forming part of an automatic cruise control system, or alternatively by a control device which is separate from an automatic cruise control system of the vehicle 1.

[0067] As the method is initiated, the vehicle 1 comprising the control device 10 is travelling on a road 100 as illustrated in FIG. 3a, and is approaching a road section 101 of a predetermined type. In this case, the road section 101 is a curve 101, but other predetermined types of road sections may e.g. be intersections, roundabouts, road sections following traffic signs, etc., for which it is normally desired to lower the vehicle speed v of the vehicle 1. The vehicle speed v is initially controlled by the control device 10 based on a set speed v.sub.set. As it is detected that the curve 101 is approaching, for example using a navigation system of the vehicle 1 or using a local environment perception sensor, the control device 10 starts to lower the vehicle speed v from the set speed v.sub.set towards a predetermined safe speed v.sub.safe.

[0068] In a first step S1 of the method according to an embodiment of the invention, carried out while lowering the vehicle speed towards the safe speed v.sub.safe, a request from the driver of the vehicle 1 to control the vehicle speed to a temporary vehicle speed v.sub.temp different from the predetermined safe speed v.sub.safe and the set speed v.sub.set is received in the control device 10.

[0069] In a second step S2, the control device 10 controls the vehicle speed v to the temporary vehicle speed v.sub.temp requested by the driver. The second step S2 is carried out in response to receipt of the request in step S1. The vehicle speed v may be controlled to the temporary vehicle speed v.sub.temp throughout the road section 101 of the predetermined type.

[0070] In a third step S3, carried out at an end of the road section 101 of the predetermined type, the control device 10 again automatically controls the vehicle speed v based on the set speed v.sub.set. The third step S3 may be carried out as it is detected that the vehicle 1 is at an end of the road section 101 of the predetermined type, for example using a navigation system of the vehicle or using e.g. one or more local environment perception sensors of the vehicle 1, or using a steering wheel angle sensor of the vehicle 1, or using wheel speed sensors of left- and right-hand wheels of the vehicle 1.

[0071] In a first exemplary driving scenario, the vehicle 1 is driving along the road 100 as illustrated in FIG. 3a. Furthermore, FIG. 3b schematically illustrates the vehicle speed v of the vehicle 1 as a function of vehicle position x within the curve 101. Herein, the solid line shows how the vehicle speed would be controlled in the curve 101 without intervention by the driver, while the dashed line shows how the vehicle speed may be controlled according to the method illustrated in FIG. 2 upon request of the driver. The dash-dotted line shows the vehicle speed in accordance with a second exemplary driving scenario, also described in the following.

[0072] In the first exemplary driving scenario, the control device 10 of the vehicle 1 controls the vehicle speed to a reference speed v.sub.ref, determined based on the set speed v.sub.set in combination with map data and geographic positioning information received from a navigation system of the vehicle 1. As the navigation system at a point x.sub.1 detects that the vehicle 1 approaches the curve 101, the control device 10 starts to lower the vehicle speed towards the predetermined safe speed v.sub.safe. During the deceleration, at the point x.sub.2, the driver considers that the vehicle 1 has reached a vehicle speed which is suitable for traversing the curve 101. He/she then briefly depresses the accelerator pedal 11, i.e. depresses the accelerator pedal for a short amount of time. The brief depression of the accelerator pedal 11 triggers a first type of request received in the control device 10 in the step S1. In response to the first type of request, the control device 10 sets a temporary vehicle speed v.sub.temp,1 to the current vehicle speed v at the point x.sub.2, and, in the step S2, controls the vehicle speed to this temporary vehicle speed v.sub.temp,1 while traversing the curve 101. When the navigation system detects, at a point x.sub.4, that the vehicle 1 reaches an end of the curve 101, the control device 10 in step S3 automatically controls the vehicle speed back to the reference speed v.sub.ref, determined based on the set speed v.sub.set as described above. Step S3 is carried out without interaction from the driver, thus the driver does not need to signal that he/she wishes the vehicle speed to be raised as the vehicle 1 exits the curve 101.

[0073] In the second exemplary driving scenario, the vehicle 1 approaches the curve 101 and the control device 10 consequently starts to lower the vehicle speed towards the predetermined safe speed v.sub.safe. However, the driver considers that the road is slippery, and during the deceleration, at the point x.sub.2, he/she therefore briefly depresses the brake pedal 12 of the vehicle 1. The brief depression of the brake pedal 12 triggers a second type of request received in the control device 10 in the step S1. In response to the second type of request, the control device 10 reduces the vehicle speed below the predetermined safe speed v.sub.safe until a predetermined condition is fulfilled. In this case, when the driver at a point x.sub.3 considers that the vehicle speed is sufficiently low for safely traversing the curve 101, he/she briefly depresses the accelerator pedal 11, thus triggering the first type of request such that the control device sets the current vehicle speed as a temporary vehicle speed v.sub.temp,2 for traversing the curve 101. The vehicle 1 thereafter travels through the curve 101 as described above in connection with the first exemplary driving scenario.

[0074] In both of the exemplary driving scenarios, data relating to the requests from the driver may be stored in the control device 10 together with positioning information, i.e. data relating to the geographic position of the vehicle upon receiving the requests. The stored data may be used to adapt the predetermined safe speed (v.sub.safe) of the vehicle 1, such that, if the vehicle and/or the driver travel(s) the same road 100 again, the vehicle speed for traversing the curve 101 is automatically controlled to a value which is closer to a speed that has previously been requested by the driver in that particular curve 101 than the predetermined safe speed v.sub.safe set for traversing the curve 101 the first time.

[0075] As it is detected that the vehicle 1 approaches a previously travelled curve 101, for which data relating to at least one request from the driver has been stored, the control device 10 may for example automatically control the vehicle speed to a stored temporary vehicle speed. Road and/or weather conditions may also be taken into account, for example to select a suitable stored temporary vehicle speed if the curve 101 has been travelled many times.

[0076] The control functionality of the example embodiments may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwire system. Embodiments within the scope of the present disclosure include program products comprising machine-readable medium for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0077] FIG. 4 shows a control device 400 configured for carrying out the method according to embodiments of the invention, comprising a non-volatile memory 420, a data-processing unit 410 and a read and write memory 460. The memory 420 has a first memory part 430, in which a computer program for controlling the control device 400 is stored. The computer program in the memory part 430 for controlling the control device 400 can be an operating system.

[0078] The control device 400 can be comprised in, for example, the control device 10 described above, or in another control unit of the vehicle 1. The data-processing unit 410 can comprise, for example, a microcomputer. The memory 420 also has a second memory part 440, in which a program for controlling the vehicle speed according to the invention is stored. In an alternative embodiment, the program for controlling the vehicle speed is stored in a separate non-volatile storage medium 450 for data, such as, for example, a CD or an exchangeable semiconductor memory. The program can be stored in an executable form or in a compressed state. When it is stated below that the data-processing unit 410 runs a specific function, it should be clear that the data-processing unit 410 is running a specific part of the program stored in the memory 420 or a specific part of the program stored in the non-volatile storage medium 450. The data-processing unit 410 is tailored for communication with the non-volatile storage medium 450 through a data bus 414. The data-processing unit 410 is also tailored for communication with the memory 420 through a data bus 412. In addition, the data-processing unit 410 is tailored for communication with the memory 460 through a data bus 411. The data-processing unit 410 is also tailored for communication with a data port 490 by the use of a data bus 415.

[0079] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.