Driving assistance systems

Abstract

This effectively prevents causing discomfort to the crew. [Solution] A driving assistance device capable of performing inter-vehicle distance control, which controls the distance between the vehicle and another vehicle based on a predetermined target inter-vehicle distance, comprising: an acquisition unit that acquires whether the road on which the vehicle is currently traveling or is scheduled to travel in the near future is on a downhill slope; a determination unit that determines whether the downhill slope continues for a predetermined amount or more; and an inter-vehicle distance changing unit that, if the determination unit determines that the downhill slope continues for a predetermined amount or more, changes the target inter-vehicle distance for inter-vehicle distance control to be longer.

Description

[Technical Field]

[0001] This disclosure relates to a driver assistance system. [Background technology]

[0002] For example, Patent Document 1 discloses a vehicle driver assistance device capable of performing Adaptive Cruise Control (ACC). The device described in Patent Document 1 sets a large distance between the vehicle and the preceding vehicle when stopped, because if the road gradient when the vehicle is stopped is steep, the vehicle may move unintentionally. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-138217 [Overview of the Initiative]

[0004] Even when a vehicle is following a preceding vehicle using ACC's adaptive cruise control, it may be advisable to adjust the target following distance (or target following time) to increase it when driving on an incline (especially a downhill slope) to prevent the following distance from becoming too short. However, if such adjustments are made on a short incline, the following distance to the preceding vehicle may repeatedly increase and decrease, potentially causing discomfort to the vehicle's occupants.

[0005] This disclosure is made to solve the above-mentioned problems and aims to effectively prevent discomfort to occupants by optimizing the target distance between vehicles while the vehicle is in motion using inter-vehicle distance control.

[0006] The technology disclosed herein is A driver assistance device capable of performing inter-vehicle distance control, which controls the distance between one's own vehicle and other vehicles based on a predetermined target distance, An acquisition unit that acquires whether the host vehicle is traveling under the inter-vehicle distance control or the road on which the host vehicle plans to travel in the near future has a downhill gradient; A determination unit that determines whether the downhill gradient continues for a predetermined period or more; When the determination unit determines that the downhill gradient continues for a predetermined period or more, an inter-vehicle distance change unit that changes the target inter-vehicle distance of the inter-vehicle distance control to be longer, is provided. It is characterized by the above.

Brief Description of Drawings

[0007] [Figure 1] It is a schematic diagram showing the hardware configuration of the vehicle according to the present embodiment. [Figure 2] It is a schematic diagram showing the software configuration of the control device according to the present embodiment. [Figure 3] It is a schematic diagram showing an example of a front image captured by a camera sensor mounted on a vehicle. [Figure 4] It is a flowchart for explaining a routine of changing the target inter-vehicle distance according to the present embodiment.

Modes for Carrying Out the Invention

[0008] Hereinafter, the driving support device according to the present embodiment will be described with reference to the drawings.

[0009] [Hardware Configuration] FIG. 1 is a schematic diagram showing the hardware configuration of a vehicle VH according to the present embodiment. Hereinafter, when it is necessary to distinguish the vehicle VH from other vehicles or the like, it may be referred to as the host vehicle.

[0010] The vehicle VH has an ECU (Electronic Control Unit) 10. The ECU 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, an interface device 14, etc. The CPU 11 is a processor that executes various programs stored in the ROM 12. The ROM 12 is a non-volatile memory that stores data and the like necessary for the CPU 11 to execute various programs. The RAM 13 is a volatile memory that provides a working area where various programs are expanded when executed by the CPU 11. The interface device 14 is a communication device for communicating with external devices.

[0011] The ECU 10 is a central device that performs driving assistance such as ACC. Driving assistance is a concept that includes autonomous driving. To the ECU 10, a drive device 20, a steering device 21, a braking device 22, an in-vehicle sensor device 30, an external sensor device 40, a navigation device 50, a communication device 60, an ACC operation unit 70, etc. are communicably connected.

[0012] The drive device 20 generates a driving force transmitted to the drive wheels of the vehicle VH. Examples of the drive device 20 include an electric motor and an engine. The vehicle VH may be any of a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a fuel cell vehicle (FCEV), an electric vehicle (BEV), and an engine vehicle. The steering device 21 applies a steering force to the wheels of the vehicle VH. The braking device 22 applies a braking force to the wheels of the vehicle VH.

[0013] The in-vehicle sensor device 30 is sensors that acquire the state of the vehicle VH. The in-vehicle sensor device 30 includes a wheel speed sensor 31, an accelerator sensor 32, a brake sensor 33, a steering angle sensor 34, a yaw rate sensor 35, a longitudinal and lateral acceleration sensor 36, etc.

[0014] The wheel speed sensor 31 detects the vehicle speed (vehicle speed V) of the vehicle VH. The accelerator sensor 32 detects the amount of accelerator pedal operation by the driver (not shown). The brake sensor 33 detects the amount of brake pedal operation by the driver (not shown). The steering angle sensor 34 detects the rotation angle (steering angle) of the steering wheel or steering shaft (not shown). The yaw rate sensor 35 detects the yaw rate of the vehicle VH. The longitudinal acceleration sensor 36 detects the longitudinal acceleration (longitudinal acceleration G) of the vehicle VH. The internal sensor device 30 transmits the state of the vehicle VH detected by each sensor 31 to 36 to the ECU 10 at a predetermined interval.

[0015] The external sensor device 40 consists of sensors that recognize object information relating to objects around the vehicle VH. The external sensor device 40 includes a radar sensor 41, a camera sensor 42, etc. Here, object information can be, for example, surrounding vehicles, road markings, road signs, etc.

[0016] The radar sensor 41 detects targets present around the vehicle VH. The radar sensor 41 includes a millimeter-wave radar and / or a lidar. The millimeter-wave radar emits radio waves in the millimeter-wave band and receives millimeter waves reflected by targets within its radiation range. The millimeter-wave radar acquires the relative distance and relative speed between the vehicle VH and the target based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the transmission of the millimeter waves to the reception of the reflected waves. The lidar sequentially scans pulsed laser light with a wavelength shorter than millimeter waves in multiple directions and receives the reflected light reflected by targets to acquire the shape of targets detected around the vehicle VH, the relative distance and relative speed between the vehicle VH and the targets.

[0017] The camera sensor 42 captures images of the area around the vehicle VH and processes the captured image data to acquire target information around the vehicle VH. For example, a digital camera with an image sensor such as a CMOS or CCD can be used as the camera sensor 42. The target information includes the type of target detected around the vehicle VH, the relative distance between the vehicle VH and the target, and the relative speed. The type of target can be recognized, for example, by machine learning such as pattern matching.

[0018] The external sensor device 40 transmits the acquired target information to the ECU 10 at predetermined intervals. The external sensor device 40 does not necessarily need to include both the radar sensor 41 and the camera sensor 42; for example, it may include only the radar sensor 41 or only the camera sensor 42.

[0019] The navigation system 50 includes a location information acquisition device 51 and a map database 52. The location information acquisition device 51 is, for example, a GPS (Global Positioning System), GNSS (Global Navigation Satellite System), etc., and acquires the current location information of the vehicle VH. The map database 52 is a database of map information and is stored in a storage device (hard disk, flash memory, etc.) provided by the vehicle VH. The map information includes coordinate data such as the latitude, longitude, and altitude of roads. The map database 52 may also be stored in an external server that can communicate with the vehicle VH. In this case, the vehicle VH can acquire map information from the external server via the communication device 60.

[0020] The communication device 60 performs V2X communication. Specifically, the communication device 60 performs V2V (Vehicle to Vehicle) communication between its own vehicle VH and other vehicles, and V2I (Vehicle to Infrastructure) communication between its own vehicle VH and infrastructure. Through V2X communication, the communication device 60 can acquire information about the surroundings of its own vehicle VH, or provide information about its own vehicle VH. The communication device 60 transmits the acquired surrounding information to the ECU 10 at predetermined intervals.

[0021] The ACC control unit 70 includes, for example, an activation switch for the driver to select whether to start or stop ACC, a setting switch for setting the target vehicle speed and target distance (target interval time) for ACC, a cancel switch for temporarily disabling ACC, and a resume switch for restarting ACC.

[0022] [Software Configuration] Figure 2 is a schematic diagram showing the software configuration of the control device according to this embodiment.

[0023] As shown in Figure 2, the ECU 10 includes functional elements such as an ACC control unit 100, a gradient road driving start determination unit 110, a gradient road driving end determination unit 120, and an inter-vehicle distance change processing unit 130. Each of these functional elements 100 to 130 is realized by the CPU 11 of the ECU 10 reading a program stored in the ROM 12 into the RAM 13 and executing it. Note that all or part of each of the functional elements 100 to 130 may also be provided in another ECU separate from the ECU 10, or in an information processing device of a facility (such as a management center) that can communicate with the vehicle VH.

[0024] The ACC control unit 100 performs ACC based on the target vehicle speed or target inter-vehicle distance (target inter-vehicle time). As ACC itself is well known, it will be briefly explained below. ACC includes two types of control: constant speed driving control and follow driving control. Constant speed driving control is a control that makes the vehicle VH drive at a constant speed according to the target vehicle speed without requiring the driver to operate the accelerator or brake. Follow driving control is a control that makes the vehicle VH follow the preceding vehicle so that the actual inter-vehicle distance between the preceding vehicle and the vehicle VH becomes the target inter-vehicle distance (target inter-vehicle time), without requiring the driver to operate the accelerator or brake. The preceding vehicle is a vehicle located in the area in front of the vehicle VH and directly in front of the vehicle VH.

[0025] When the activation switch of the ACC operation unit 70 is turned ON, the ACC control unit 100 searches for a preceding vehicle to follow based on the detection results of the external sensor device 40. If no preceding vehicle exists, the ACC control unit 100 performs constant speed driving control. In this case, the ACC control unit 100 controls the operation of the drive unit 20 and brake unit 22 based on the target acceleration calculated from the deviation between the vehicle speed V and the target vehicle speed. The vehicle speed V can be obtained based on the detection results of the wheel speed sensor 31. On the other hand, if a preceding vehicle exists, the ACC control unit 100 performs follow driving control. In this case, the ACC control unit 100 controls the operation of the drive unit 20 and brake unit 22 based on the target acceleration calculated from the deviation between the actual distance between vehicles and the target distance (target time between vehicles). The actual distance between the vehicle VH and the preceding vehicle can be obtained based on the detection results of the external sensor device 40.

[0026] The gradient road travel start determination unit 110 is an example of the acquisition unit and determination unit of this disclosure, which acquires whether the road on which the vehicle VH is currently traveling or is scheduled to travel in the near future is a downhill slope, and determines whether the vehicle VH has started traveling on a downhill slope. The details of each embodiment of the determination process executed by the gradient road travel start determination unit 110 will be described below. The gradient road travel start determination unit 110 does not need to execute all of the following embodiments 1 to 4, but only needs to execute one of them.

[0027] [Example 1] The gradient road travel start determination unit 110 sequentially calculates the gradient θ of the road on which the vehicle VH is traveling at a predetermined period, based on the vehicle speed V detected by the wheel speed sensor 31 and the longitudinal acceleration G detected by the longitudinal acceleration sensor 36, and temporarily stores it in the storage unit (for example, ROM 12). The gradient road travel start determination unit 110 also calculates the average value of multiple gradients θn calculated over a predetermined period and stores it as a moving average value θ Ave The calculation is performed sequentially as (=Σθn / n). The gradient road travel start determination unit 110 uses the calculated moving average value θ Ave When the moving average value θ exceeds a predetermined threshold, it is determined that the vehicle VH has started traveling down a slope. AveBy using this, it becomes possible to effectively prevent the misrecognition of temporary gradient changes such as short gradients and steps as a downhill gradient road.

[0028] [Embodiment 2] The gradient road travel start determination unit 110 estimates whether the road ahead of the vehicle VH is a downhill gradient road based on the detection result of the position information acquisition device 51 included in the navigation device 50 and the coordinate data of the map database 52. Specifically, the gradient road travel start determination unit 110 identifies the current position of the host vehicle VH on the route set by the navigation device 50 based on the detection result of the position information acquisition device 51. Further, when the gradient road travel start determination unit 110 identifies the current position of the host vehicle VH, it acquires a first elevation (altitude) at a predetermined first distance ahead of the current position on the route and a second elevation (altitude) at a predetermined second distance ahead that is longer than the first distance based on the map database 52. The difference between the first distance and the second distance is not particularly limited, but it is preferably set to be long enough not to misrecognize short gradient sections and steps as a downhill gradient road. The gradient road travel start determination unit 110 estimates that the road ahead is a downhill gradient road when the second elevation is lower than the first elevation and the difference between the first elevation and the second elevation is a predetermined value or more. When the current position of the host vehicle VH reaches the entrance of the road estimated to be a downhill gradient road, the gradient road travel start determination unit 110 determines that the vehicle VH has started traveling on the downhill gradient road.

[0029] [Embodiment 3] In Embodiment 3, it may be executed by the gradient road travel start determination unit 110 which is a part of the functional elements of the ECU 10, or may be executed by a server device installed in a management center or the like through the communication device 60 to communicate with the vehicle VH. The gradient road travel start determination unit 110 acquires the ON (F ACC = 1) of the ACC flag F indicating that the ACC control unit 100 is executing ACC and the ON (F ACC = 1) of the preceding vehicle flag F indicating that a preceding vehicle to be followed is detected. Further, the gradient road travel start determination unit 110 acquires the ON (F V = 1) of the ACC flag F V = 1) of the ACC flag F ACC = 1) of the ACC flag F ACC=1) and the preceding vehicle flag F V On (F V When =1) is obtained, it is determined whether the driver cancels the ACC. The ACC may be canceled by either the driver pressing the brake pedal or by pressing the cancel switch on the ACC control unit 70.

[0030] The gradient road driving start determination unit 110 flags a cancellation flag F to indicate that the driver has canceled ACC. C On (F C When =1) is obtained, the direction of travel and position information of the vehicle VH at that time are obtained based on the detection result of the position information acquisition device 51, and are stored in the storage unit (for example, ROM 12) as a cancellation position. The gradient road travel start determination unit 110 estimates that the cancellation position that has occurred frequently and has occurred more than a predetermined number of times is a downhill gradient, and when the vehicle VH reaches the same cancellation position in the same direction of travel on the next time or later, it determines that the vehicle VH has started traveling on a downhill gradient.

[0031] [Example 4] In Example 4, similar to Example 3, the gradient road driving start determination unit 110, which is part of the functional elements of the ECU 10, may perform the action, or a server device installed in a management center or the like may perform the action by communicating with the vehicle VH through a communication device 60. The gradient road driving start determination unit 110 uses the ACC flag F ACC On (F ACC =1) and the preceding vehicle flag F V On (F V With the value =1) obtained, the direction of travel of vehicle VH, the target distance between vehicles, and the actual distance between vehicles are obtained. The actual distance between vehicles can be obtained based on the detection result of the external sensor device 40. The gradient road start travel determination unit 110 estimates a position where the actual distance between vehicles is frequently closer to the target distance by a predetermined distance or more as a downhill slope, and stores that position in the storage unit (for example, ROM 12). The gradient road start travel determination unit 110 determines that vehicle VH has started traveling on a downhill slope when vehicle VH reaches that position in the same direction of travel on subsequent occasions.

[0032] The gradient road travel completion determination unit 120 determines whether or not the vehicle VH has finished traveling down the gradient road. The details of each embodiment of the determination process executed by the gradient road travel completion determination unit 120 are described below. The gradient road travel completion determination unit 120 does not need to execute all of the following embodiments 5 to 7; it is sufficient to execute any one of them.

[0033] [Example 5] The gradient road travel completion determination unit 120 sequentially calculates the gradient θ of the road on which the vehicle VH is traveling at a predetermined period, based on the vehicle speed V of the vehicle VH detected by the wheel speed sensor 31 and the longitudinal acceleration G of the vehicle VH detected by the longitudinal acceleration sensor 36, and temporarily stores it in a storage unit (for example, ROM 12). The gradient road travel completion determination unit 120 also calculates the average value of multiple gradients θn calculated over a predetermined period and stores it as a moving average value θ Ave The calculation is performed as (=Σθn / n). The gradient road travel completion determination unit 120 uses the calculated moving average value θ Ave When the value decreases from above a predetermined threshold to below that threshold, it is determined that the vehicle VH has finished traveling on a downhill slope (i.e., has moved to a flat road).

[0034] [Example 6] The gradient road travel completion determination unit 120 estimates whether the road ahead of the vehicle VH is flat based on the detection results of the position information acquisition device 51 of the navigation device 50 and the coordinate data of the map database 52. Specifically, the gradient road travel completion determination unit 120 identifies the current position of the vehicle VH on the route set by the navigation device 50 based on the detection results of the position information acquisition device 51. After identifying the current position of the vehicle VH, the gradient road travel completion determination unit 120 acquires a first elevation approximately 1 distance ahead of the current position on the route and a second elevation approximately 2 distance ahead. After the gradient road travel start determination unit 110 has determined that the vehicle has started traveling on a downhill slope, the gradient road travel completion determination unit 120 estimates the road ahead to be flat if the difference between the first elevation and the second elevation falls below a predetermined value. The gradient road travel completion determination unit 120 determines that vehicle VH has finished traveling on a downhill slope when the vehicle VH reaches the entrance of a road that is estimated to be a flat road.

[0035] [Example 7] The gradient road travel completion determination unit 120 determines whether vehicle VH has finished traveling down the gradient road based on the detection results of the external sensor device 40. Figure 3(A) shows an example of an image taken by the camera sensor 42 when vehicle VH and the preceding vehicle VH2 are traveling down the gradient road. Figure 3(B) shows an example of an image taken by the camera sensor 42 when vehicle VH is traveling down the gradient road and the preceding vehicle VH2 moves from the gradient road to a flat road.

[0036] When the image captured by the camera sensor 42 changes from the state shown in Figure 3(A) to the state shown in Figure 3(B), the gradient road travel completion determination unit 120 compares the relative distance D1 between the vehicle VH and the preceding vehicle VH2 acquired by the camera sensor 42 with the relative distance D2 between the vehicle VH and the preceding vehicle VH2 acquired by the radar sensor 41. If the difference between relative distance D1 and relative distance D2 is greater than or equal to a predetermined value, the gradient road travel completion determination unit 120 estimates the position of the preceding vehicle VH2 to be the entrance to a flat road. When the current position of the vehicle VH reaches the entrance to the road estimated to be a flat road, the gradient road travel completion determination unit 120 determines that the vehicle VH has finished traveling on the downhill slope.

[0037] The inter-vehicle distance change processing unit 130 is an example of the inter-vehicle distance change unit of this disclosure, and the ACC flag F ACC On (F ACC =1) and the preceding vehicle flag F V On (F VWhen the gradient road travel start determination unit 110 determines that travel on a downhill slope has started while the value =1) is obtained, it performs a modification process to correct the target inter-vehicle distance (or target inter-vehicle time) to be longer by a predetermined addition amount α. The addition amount α is not particularly limited and may be a fixed value or a variable value. If it is a variable value, for example, the addition amount α may be set to be larger the larger the gradient θ or the current vehicle speed V. Alternatively, the braking distance L0 (or braking time T0) when decelerating on a flat road with the current vehicle speed V and a predetermined brake torque, and the braking distance L1 (or braking time T1) when decelerating on the downhill slope currently being traveled with the same vehicle speed and brake torque may be calculated, and the difference between these (=L1-L0, T1-T0) may be set as the addition amount α.

[0038] Thus, when vehicle VH starts driving on a downhill slope while follow-me driving control is in operation, the target following distance (or target following time) can be changed to a longer value, making it possible to maintain an appropriate following distance that matches the driver's perception. Furthermore, by maintaining an appropriate following distance, the hassle of the driver having to manually change the target following distance using a setting switch can be reduced, and it is also possible to effectively prevent the driver from feeling uneasy and canceling the ACC. In addition, in this embodiment, the aforementioned slope driving start determination unit 110 determines that driving on a downhill slope has started only when vehicle VH is driving on a downhill slope that continues for a predetermined period of time or longer. In other words, it is possible to prevent the target following distance (or target following time) from being repeatedly changed on short sections of downhill slopes or over bumps, and it is also possible to effectively prevent discomfort to the occupants of vehicle VH.

[0039] The inter-vehicle distance change processing unit 130 changes the target inter-vehicle distance (or target inter-vehicle time) to be longer by an amount α, and then, when the gradient road travel completion determination unit 120 determines that the downhill road travel has ended, it returns the target inter-vehicle distance (or target inter-vehicle time) to its original setting value.

[0040] Figure 4 is a flowchart illustrating the routine for changing the target inter-vehicle distance (or target inter-vehicle time) executed by the CPU 11 of the ECU 10. This routine is started, for example, when vehicle VH is driving.

[0041] In step S100, the ECU10 checks whether ACC is running, i.e., the ACC flag F ACC is on (F ACC Determine whether it is =1. ACC flag F ACC is on (F ACC If =1) (Yes), ECU10 proceeds to step S110. Meanwhile, ACC flag F ACC is off (F ACC If = 0 (No), ECU10 returns this routine.

[0042] In step S110, the ECU10 checks whether there is a preceding vehicle to be followed ahead of its own vehicle VH, i.e., the preceding vehicle flag F. V is on (F V Determine whether it is =1. Preceding vehicle flag F V is on (F V If =1) (Yes), ECU10 proceeds to step S120. Meanwhile, the preceding vehicle flag F V is off (F V If = 0 (No), ECU10 returns this routine.

[0043] In step S120, the ECU10 determines whether the vehicle VH has started traveling downhill. If it determines that the vehicle VH has started traveling downhill (Yes), the ECU10 proceeds to step S130. On the other hand, if it does not determine that the vehicle VH has started traveling downhill (No), the ECU10 returns to this routine.

[0044] In step S130, the ECU 10 calculates an amount α to increase the target distance between vehicles (or target time between vehicles). Then, in step S140, the ECU 10 performs a modification process to increase the target distance between vehicles (or target time between vehicles) by adding the amount α to the target distance between vehicles (or target time between vehicles).

[0045] In step S150, the ECU 10 determines whether the vehicle VH has finished traveling down the slope. If it determines that the vehicle VH has finished traveling down the slope (Yes), the ECU 10 proceeds to step S160. On the other hand, if it does not determine that the vehicle VH has finished traveling down the slope (No), the ECU 10 repeats the process in step S150.

[0046] In step S160, ECU10 returns the target distance (or target time) to its original setting. In other words, it returns to the normal ACC follow-me driving control that was in place before the change. After that, ECU10 returns this routine.

[0047] Although the driving assistance device according to this embodiment has been described above, this disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the purpose of this disclosure.

[0048] For example, if the vehicle (VH) is being followed on a downhill slope by a following vehicle equipped with V2V communication capabilities, it is possible to configure the system to send a request to the following vehicle via V2V communication to increase the target inter-vehicle distance, and for the following vehicle to accept this request. Furthermore, when the vehicle (VH) equipped with V2I communication capabilities and another vehicle are traveling downhill using ACC (Adaptive Cruise Control), it is also possible to configure the system to send a request from the infrastructure side to increase the target inter-vehicle distance, and for both the vehicle and the other vehicle to accept this request. The technology disclosed herein can also be applied to autonomous vehicles that perform some or all of the driving operations automatically.

Claims

[Claim 1] A driver assistance device capable of performing inter-vehicle distance control, which controls the distance between one's own vehicle and other vehicles based on a predetermined target distance, An acquisition unit that acquires whether the road on which the vehicle is currently traveling or is scheduled to travel in the near future, based on the distance control between vehicles, is on a downhill slope. A determination unit that determines whether the downward slope continues for a predetermined amount or more, The system includes a distance adjustment unit that, when the determination unit determines that the downward slope continues for a predetermined amount or more, changes the distance control to increase the target distance between vehicles. A driving assistance device characterized by the following features.

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