METHOD FOR A VEHICLE CRUISE CONTROL AND UNIT OF A PREDICTIVE CRUISE CONTROL

Abstract

Method for a vehicle cruise control system, wherein the method comprises that: a vehicle (101, 501, 601) is provided which is designed to travel at a speed which is automatically determined, at least in part, from digital map data (521B) pertaining to a road (105) on which the vehicle (101, 501, 601) is traveling; Speed ​​data for an upcoming road segment are obtained from map data (521B) belonging to the upcoming road segment; an automatically determined speed is calculated based at least partially on the speed data of the upcoming road segment; wherein the automatically set speed is adjusted by an offset speed derived from a user-selected speed (523A) received via a human-machine interface (HMI) (523), wherein the offset speed is a speed deviation between a current speed limit (521A) supplied by the database (521) and indicated by a road sign (104, 106) at the time the user selected the desired speed and the speed (523A) selected by the user itself, and wherein the speed deviation is maintained during speed changes; and at least one transition speed (408A) is supplied as a speed command to an adaptive cruise control (411), wherein the transition speed (408A) is derived at least partially from the automatically set speed.

Description

BACKGROUND

[0001] The present invention relates generally to a vehicle cruise control system and specifically to improving driving ability by automatically adjusting the driving speed in a safe and comfortable manner in anticipation of upcoming changes in road conditions, even in situations where no suitable road or GPS data is available.

[0002] DE 10 2010 006 442 A1 discloses a method for integrating an adaptive multi-feature cruise control system. This cruise control system integrates features of adaptive cruise control, speed limit adherence, and cornering speed control with a conventional cruise control system. The multi-feature cruise control system receives input from a driver input device, a forward-facing sensor device, and a GPS positioning device. The various integrated cruise control functions each provide a speed and acceleration value, which can differ. A selection is made based on a minimum set of values. Further prior art is known from WO 2010 / 139 383 A1 and DE 697 21 999 T2. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The object of the invention is to provide an improved method for a vehicle cruise control and an improved unit for a predictive cruise control.

[0004] To solve the problem, a method with the features of claim 1 and a unit with the features of claim 8 are provided. Advantageous embodiments of the invention can be found in the dependent claims, the description, and the drawings.

[0005] The subject matter considered to be the invention is specifically highlighted and clearly claimed in the concluding part of the application. The features, operating method, primary components, and advantages of the present predictive cruise control can best be understood by reference to the following detailed description and the accompanying drawings, which: Fig. 1 a schematic representation of a vehicle that travels at automatically selected speeds based on speed limit data for each respective road segment, according to embodiments; Fig. 2 a general block diagram illustrating the relationship between the automatic speed setting system in an adaptive cruise control (ACC) and an engine control module (ECM), according to embodiments; Fig. 3 a block diagram of a velocity command generator with the associated submodules and the associated data flow according to embodiments; Fig. 4 a schematic representation of a vehicle that travels at several automatically selected speeds based on curve speed data for each respective segment and a user-selected offset speed, according to embodiments; Fig. 5. A block diagram of a velocity command generator with its associated submodules and data flow, which demonstrate the functionality of Fig. 4 provide, according to embodiments; Fig. 6 a schematic representation of curve segments used in the calculation of curve speeds by the speed command generator according to embodiments; Fig. 7 a schematic representation of different transition speeds without reliable navigation or map data according to embodiments; Fig. 8 a flowchart used by the automatic speed determination system to determine the in Fig. 1 or Fig. 4. To achieve the functionality shown, according to embodiments; and Fig. 9 A schematic block diagram showing the hardware used to perform the tasks described in Fig. 1 - 8 to achieve the functionality described, according to embodiments. DETAILED DESCRIPTION

[0006] The following non-restrictive detailed description demonstrates that it should be recognized that methods, procedures and components widely known to those skilled in the art have not been described for the sake of simplification, and that the non-restrictive features enable embodiments of the present invention.

[0007] In general, non-restrictive embodiments of the present invention are directed towards improving a vehicle cruise control system in the following way: - Automatically modifying the travel speed in response to upcoming changes in road conditions in a gradual, safe and comfortable manner. - Integrating driver-selected speeds with speeds automatically determined based on map data. - Providing safeguards to ensure such functionality during periods of unsuitable map data or lost global positioning system (GPS) signals.

[0008] The following definitions are used in the application: “Adaptive Cruise Control (ACC)” refers to a cruise control system designed to automatically adjust the vehicle speed to maintain a predefined distance behind a vehicle ahead while maintaining a selected cruising speed.

[0009] "Speed ​​command generator" refers to an add-on or retrofit device for the ACC. The speed command generator is designed to provide the ACC with a speed command that reflects upcoming road conditions.

[0010] “Unit of a predictive cruise control” refers to the combination of the ACC and the speed control generator.

[0011] “Speed ​​provisioning device” refers to a functional unit of the speed command generator that is aimed at securing speed data for use in automatically setting driving or cruising speeds.

[0012] “Auto-set speed”, “automatically set speed” and “automatically selected” speed all refer to a driving speed that is automatically set based on map data or map data combined with an offset speed derived from a speed selected by a user.

[0013] "Speed ​​control unit" refers to a functional unit of the speed command generator that is responsible for selecting a single transition speed, which is then supplied to the ACC as a speed command. The speed control unit includes additional functionality, as explained below.

[0014] “Driver-selected speed” refers to a speed that is manually entered into the speed command generator via a human-machine interface (HMI).

[0015] "Map data" refers to digital data stored in a database.

[0016] "Map" is an acronym referring to the fact that the system provides data regarding road profiles or road conditions. For the purposes of this registration, "map data," "MAP" data, and "road map data" are used interchangeably.

[0017] "Curving speed" refers to the optimal speed at which a curve should be driven.

[0018] “Offset speed” refers to a speed deviation between a current speed limit at the time a driver selects a desired cruising speed and a speed selected by the driver itself. This deviation can either exceed or fall below the speed limit and, according to embodiments, is maintained during speed changes.

[0019] It should be noted that a speed command generator is used in many types of terrestrial vehicles, including cars, trucks, motorcycles, and bicycles.

[0020] Now, referring to the characters... Fig. 1. According to embodiments, a schematic representation of a vehicle is configured to automatically determine its speed based on digital map data belonging to a road segment where vehicles are identified as moving by GPS. The vehicle is further configured to receive speeds selected by the driver via a human-machine interface (HMI). As mentioned above, the deviation of the user-selected speed from the current speed limit defines an offset speed. According to non-restrictive embodiments, the vehicle receives the predefined offset speed when it automatically changes its speed based on the map data.It should be noted that, according to certain embodiments, automatically selected speeds based on curve data derived from the map data for the upcoming segments can also be used.

[0021] As shown, a road 105 crossing a state border 109 is divided into two road segments, 111 and 113, based on the change in the speed limit. Road segment 111 has a speed limit of 113 km / h (70 mph), as indicated by road sign 104, and road segment 113 has a speed limit of 105 km / h (65 mph), as shown by road sign 106. In this example, a driver has selected a user-defined speed with an offset speed of 8 km / h (5 mph) above the current speed limit along road segment 111. The vehicle's speed automatically changes when it crosses border 109, according to the relevant speed limit, while maintaining the 8 km / h (5 mph) offset.) is maintained above the speed limit specified in road segment 111; consequently, vehicle 101 travels at a speed of 113 km / h (70 mph) in road segment 113.

[0022] Fig. Figure 2 is a general block diagram illustrating the functional context in which the present invention is operated and the primary functional modules according to embodiments.

[0023] Specifically, according to embodiments, a speed command generator 408 delivers a speed command 408A to an ACC 411, which, after processing, outputs the appropriate acceleration and torque commands 411A to a motor control module 413. The speed command 408A is implemented in such a way that it is compatible with a wide range of ACC types. In this way, the speed command generator can be implemented as an expansion module or retrofit unit for existing adaptive cruise control units or as a single unit with a predictive cruise control unit.

[0024] The speed command generator 408 can comprise three primary modules: a speed provisioning device 425, an automatic speed setting module 420 for generating speed profiles from speed options received from the speed provisioning device 425, and a speed command module 407 for selecting a single speed for use as a speed command supplied to the ACC.

[0025] The speed provisioning device 425 can receive a speed selected by the driver or user via an HMI, as mentioned above, or from a database of map data and a GPS signal to identify the relevant map data as the location where the vehicle is moving along a road.

[0026] The automatic speed setting module 420 processes the speed data received from the speed provisioning device to generate different speed options, as further explained.

[0027] The speed command module 407 further processes the various speed options received from the module 420 for automatic speed setting in order to evaluate which of the speed options is the safest and most comfortable speed, and accordingly sends a speed command 411A.

[0028] Fig. Figure 3 is a block diagram of the primary modules, the respective submodules of the Velocity Command Generator 408 and the associated data flow.

[0029] Specifically, the speed command generator 408 comprises an HMI 523 and a map database 521 as mentioned above. The automatic speed setting module 420 includes a speed offset calculator 527 for calculating offset speeds from user-selected speeds received by the HMI 523, and a speed profile generator 529 for generating automatically selected speeds 529A, which could be incorporated into the transition speeds 408A (after additional processing) and supplied to the ACC 411 as speed commands.The speed command module 407 includes an arbitration module 531 for selecting a speed option considered to be the safest, and a safety logic module 533 for ensuring that forces generated during speed changes do not exceed comfort thresholds determined during studies of human factors.

[0030] According to a particular non-restrictive embodiment, during operation a driving speed 523A selected by the driver is received via the HMI 523 and fed to the speed offset computing unit 527 to be used to calculate an offset speed in view of the current speed limit 521A supplied by the database 521. As mentioned above, the offset speed can be evaluated as the deviation between the user-supplied speed 523A and the current speed limit 521A.

[0031] According to embodiments, the speed profile generator 529 generates at least one potential transition speed 529A based on the known position of the vehicle, map data 521B including data of an upcoming speed limit, and the distance 521B to the upcoming road segment. As shown in one embodiment, each potential transition speed 529A generated by the speed profile generator 529 is modified by an offset value 527A and output as a speed option to the arbitration module 531.

[0032] The arbitration module 531 evaluates which of the speed options—the user-selected speed 523B or the automatically selected speed 420A—is considered safest. It generally selects the lowest speed and outputs this as the reference speed to the safety module 533. It should be noted that under certain conditions, such as when the user-selected speed is lower than the speed limit, an automatically selected speed option may be chosen as the safest.

[0033] According to embodiments, a reference speed 531A is supplied to the safety module 533 to determine whether the G-force generated when changing the current speed to the preferred speed 531A is less than approximately 0.15 G-force. If so, according to embodiments, the reference speed 531A is considered the desired transition speed between the current and the upcoming road segment and is supplied to the ACC as a speed command 408A.

[0034] However, if the reference velocity 531A generates a g-force that exceeds the maximum permissible g-force of approximately 0.15 g, according to embodiments, a prior value of the preferred velocity 531A that generates a permissible g-force is supplied to the ACC 411 as a velocity command 408A.

[0035] Fig. Figure 4, according to embodiments, is a schematic view of a vehicle 501 negotiating a curve 400 at several curve speeds 505-509 to ensure a safe and comfortable transition through the curve. The curve speeds are generated from map data according to road curve conditions and can also be used when the map data does not contain speed limits for the curved road segments. The offset speed of 8 km / h (5 mph), which was set at the beginning of the curve, is maintained at each of the curve speeds according to certain embodiments. It should be noted that, according to certain embodiments, automatically selected speeds based on speed limit data derived from the map data for the upcoming segments can also be used.

[0036] Fig. Figure 5 is a block diagram of the primary modules, the respective submodules of the speed command generator 408 and the associated data flow, which are described in Fig. 4. Provide the functionality shown.

[0037] Specifically, the block diagram is analogous to the one in Fig. The three shown are identical, with the exception that additional submodules are designed to provide curve transition speeds based on map data. Map data is commercially available from NAVTEQ Corporation, 425 West Randolph Street, Chicago, Illinois 60606 USA, and online at http: / / corporate.navteq.com / products_data_whatis.htm.

[0038] A curvature calculation device 544 determines the sharpest curvature closest to the vehicle as a speed-defining curvature 544A based on map data and outputs the values ​​544A to a curve speed calculation device 540, which calculates the desired curve speed as explained below. According to one embodiment, a speed profile generator 550 calculates a speed profile based on curve speeds 540A received from the curve speed calculation device 540 and the current distance and speed of the vehicle, so that the vehicle achieves the desired curve speeds without radical speed changes. It should be noted that in certain embodiments, alternative sources for curve data, such as vehicle-to-vehicle reporting, may be used.

[0039] Analogous to the block diagram of Fig. 3. Three potential speeds, the user-selected speed 523A, the automatically selected speed 420A, and the curve-based speed 550A, are output to an arbitration module 551 to determine which of the speed options is considered the safest, and the processing proceeds as above with respect to Fig. 3 continued as described.

[0040] Fig. Figure 6 shows various curves encountered by a vehicle 601 traveling along a curve 605. The curves are shown at corresponding distances, measured from line 611, which the vehicle 601 crosses, as 620, 622, 624, and 626; 625, 627, and 629, respectively. The desired curve speed can be calculated according to a specific embodiment using the following formula: vdes_curve=R⋅ay,lim where “a y _ lim “refers to a lateral acceleration constant;

[0041] "R" refers to the radius of curvature, calculated as the reciprocal of the curvature values. These curvature values ​​are those calculated and used to generate the desired cornering speeds, as described above.

[0042] Fig. Figure 7 shows a vehicle traveling on road segments according to embodiments, using dead reckoning navigation to compensate for a loss of GPS signal or unsuitable map data.

[0043] In the event of a loss of GPS signal or map data, the speed command generator is designed to issue a warning signal to the driver to alert him to a potential need to take a more active role in controlling the vehicle's speed.

[0044] The speed command generator is further designed to operate in a backup mode that uses dead reckoning to ensure the vehicle's location while in motion, employing wheel rotation or other distance tracking methods. A target speed profile is generated based on the distance traveled, speed limit information obtained from the MAP data speed limits of the current and next road segments, and curvature data for 300–500 m of the upcoming road. Thus, according to embodiments, the speed profile for the current road segment can be generated from the data previously received from the MAP before the GPS signal was lost.

[0045] In situations where the MAP data is unsuitable and the GPS signal is maintained, speed profiles based on MAP data for previous road segments can be generated according to a specific embodiment.

[0046] Fig. Figure 8 is a non-restrictive example of a flowchart of the processing used in the speed command generator. The generator verifies in step 801 that the ACC is turned on, and if so, receives a speed selected by the driver in step 803.

[0047] In step 807, the generator automatically determines a current speed based on GPS and speed limits in map data.

[0048] In step 811, the automatically set speed is adjusted by an offset speed derived from the speed selected by the driver and speed limit data.

[0049] In step 817, data on an upcoming curve and speed limit of the upcoming road are obtained from map data.

[0050] In step 821, an automatically selected driving speed is generated based on the speed limit data and the offset speed for upcoming road segments.

[0051] In step 823, a driving speed profile is generated based on curve data for upcoming road segments.

[0052] In step 825, the safest or lowest of each set of speed options is selected as the reference speed. The speed options are the user-selected speed, the automatically set speed, and the curve-based driving speed.

[0053] In step 831, the reference speed is checked for compliance with safety thresholds.

[0054] In step 833, a speed command is sent to the ACC.

[0055] Fig.Figure 9 is a schematic block diagram of the hardware used to implement a speed command generator according to an embodiment of the present invention. A speed command generator 900 can comprise one or more GPS receivers 910, processors or controllers 920, a memory 930, a non-transient long-term memory 940, input devices 950, and output devices 960, mounted in a vehicle platform.

[0056] Non-restrictive examples include a visual and acoustic output device. The 950 input devices and the 960 output devices can be combined into a single device.

[0057] The processor or controller 920 can be, for example, a central processing unit (CPU), a chip, or any suitable computing device. The processor or controller 920 can comprise multiple processors and can include general-purpose processors and / or dedicated processors, such as graphics processing chips. The processor 920 can execute code or instructions stored, for example, in the memory 930 or the long-term memory 940 to execute embodiments of the present invention.

[0058] The Memory 930 can comprise random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), a double data rate memory chip (DDR memory chip), flash memory, volatile memory, non-volatile memory, cache memory, buffer, short-term memory unit, long-term memory unit, or other suitable memory or storage units. The Memory 930 can represent or comprise multiple memory units.

[0059] The non-transient long-term storage device 940 can, for example, be or comprise a hard disk drive, a floppy disk drive, a compact disk drive (CD drive), a CD-Recordable drive (CD-R drive), or a flash memory device. It should be noted that various combinations of the above storage devices are also included within the scope of protection of the present invention, and that image data, code, and other relevant data structures are stored in the aforementioned storage and / or storage devices.

[0060] It should be noted that, for the sake of simplicity and clarity, elements shown in the figures are not necessarily drawn to scale and reference symbols may be repeated in different figures to indicate corresponding or analogous elements.

Claims

[1] A method for a vehicle cruise control system, the method comprising: providing a vehicle (101, 501, 601) configured to travel at a speed automatically determined at least in part from digital map data (521B) associated with a road (105) on which the vehicle (101, 501, 601) is traveling; obtaining speed data of an upcoming road segment from map data (521B) associated with the upcoming road segment; an automatically set speed is calculated based at least in part on the speed data of the upcoming road segment; wherein the automatically set speed is adjusted with an offset speed derived from a user-selected speed (523A) received via a human-machine interface (HMI) (523), wherein the offset speed is a speed deviation between a current speed limit (521A) provided by the database (521) and indicated by a road sign (104, 106) at the time the user selected the desired speed and the user-selected speed (523A) itself, and wherein the speed deviation is maintained during speed changes; and at least one transition speed (408A) is provided as a speed command to an adaptive cruise control (411), wherein the transition speed (408A) is at least partially derived from the automatically set speed. [2] The method of claim 1, wherein the speed data of an upcoming road segment comprises a speed limit of the upcoming road segment. [3] The method of claim 1, wherein the speed data of an upcoming road segment comprises curve data. [4] The method of claim 1, wherein the transition speed (408A) is selected from the automatically set speed and the user selected speed (523A) with a minimum value. [5] The method of claim 4, wherein the transition speed (408A) produces less than about 0.15 G-force during speed changes. [6] The method of claim 1, further comprising employing dead reckoning in response to a loss of GPS service or a loss of map data (521B) associated with the upcoming road segment. [7] The method of claim 6, further comprising issuing a warning signal in response to a loss of GPS service or map data (521B) associated with the upcoming road segment. [8] Predictive cruise control unit, comprising: an adaptive cruise control (ACC) (411) associated with a vehicle (101, 501, 601); a speed command generator (408, 900) in communication with the ACC (411), wherein the ACC (411) comprises a processor (920) configured to: retrieve speed data from a database (521) of map data (521B) associated with an upcoming road segment; to calculate at least one automatically set speed from the map data (521B); wherein the automatically set speed is adjusted with an offset speed derived from a user-selected speed (523A) received via a human-machine interface (HMI) (523), wherein the offset speed is a speed deviation between a current speed limit (521A) provided by the database (521) and indicated by a road sign (104, 106) at the time the user selected the desired speed and the user-selected speed (523A) itself, and wherein the speed deviation is maintained during speed changes; and provide a transition speed (408A) as a command speed to an ACC (411), wherein the transition speed (408A) is based at least in part on the automatically set speed. [9] The predictive cruise control system of claim 8, wherein the processor (920) is further configured to employ dead reckoning in response to a loss of GPS service or a loss of map data (521B) associated with the upcoming road segment.

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