Vehicle travel control device

Abstract

The invention provides a travel control device for a vehicle. The travel control device executes travel control capable of avoiding sinking in water, sinking in the water or the like in a vehicle such as an automobile. This vehicle travel control device is provided with: a surrounding environment recognition device (10) that acquires surrounding environment information of a vehicle (M); brake control devices (23, 33) that perform brake control of the vehicle; and driving force control devices (22, 32F, 32R) that drive and control front wheels and rear wheels independently. And a control means (14) that includes at least a bad road area entry determination unit (15) that determines that the vehicle enters the bad road area, and a road surface [mu] estimation unit (16) that estimates the friction coefficient of the wheel ground contact surface. When it is determined that the vehicle is to enter a region where the vehicle is easily trapped in the bad road region, the first avoidance control is executed, and then the second avoidance control is executed.

Description

Technical Field

[0001] The present invention relates to a vehicle travel control device that can execute travel control in a vehicle such as an automobile to prevent the vehicle from being submerged in water or getting stuck when traveling on a bad road area. Background Art

[0002] Conventionally, in vehicles such as automobiles, so-called all-wheel drive vehicles having a structure capable of driving all wheels (usually four wheels) of the front and rear wheels are in practical use and widely used, for example, in general four-wheel vehicles.

[0003] Such all-wheel drive vehicles generally have high bad road performance, and therefore are expected to be widely used in various driving environments. For example, when driving on unpaved roads such as bad roads and / or areas such as rough ground, the vehicle may enter areas with accumulated water, mud, or snow. In this case, the vehicle may become submerged in water and unable to drive, or may become a so-called stuck vehicle state where the drive wheels spin idly.

[0004] In such a situation, when the vehicle is about to get stuck, if it is an all-wheel drive vehicle, for example, even if the front wheels are stuck in mud, the vehicle can be pulled out of the mud by the driving force of the rear wheels. However, if more driving force than necessary is given to the front wheels at this time, the front wheels may spin, and the vehicle may get stuck further.

[0005] Therefore, various technologies have been proposed in the past, such as Japanese Patent Application Laid-Open No. 2009-78592, for example, regarding a driving control device for switching driving force at an appropriate timing in an all-wheel drive vehicle to perform drive control for escaping a stuck state of the vehicle.

[0006] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2009-78592 Summary of the invention Technical issues However, in the conventional control performed only by the travel control device disclosed in Japanese Patent Application Laid-Open No. 2009-78592 and the like, it is not always possible to reliably realize the vehicle's escape from the stuck state.

[0007] Therefore, when driving a vehicle in a bad road area, it is desirable to drive the vehicle while avoiding entering an area with accumulated water, mud, or accumulated snow.

[0008] An object of the present invention is to provide a vehicle travel control device that can perform travel control in a vehicle such as an automobile so as to avoid the vehicle from being submerged in water or getting stuck when traveling in a bad road area.

[0009] Technical Solution In order to achieve the above-mentioned purpose, a driving control device of a vehicle in one embodiment of the present invention includes a surrounding environment recognition device for acquiring surrounding environment information of the vehicle, a braking control device for performing braking control of the vehicle, a driving force control device for independently driving and controlling the front wheels and the rear wheels, and a control unit that at least includes a bad road area entry determination unit for determining whether the vehicle enters a bad road area and a road surface μ estimation unit for estimating the friction coefficient of the wheel contact surface. When the control unit determines that the vehicle is about to enter an area in the bad road area that is prone to getting stuck based on a determination result obtained by the bad road area entry determination unit, the control unit executes a first avoidance control and then executes a second avoidance control.

[0010] Technical Effects According to the present invention, it is possible to provide a vehicle travel control device that can perform travel control in a vehicle such as an automobile to avoid the vehicle from being submerged in water or getting stuck when traveling in a bad road area. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a block diagram showing a schematic configuration of a vehicle travel control device according to one embodiment of the present invention.

[0012] Figure 2 This is a diagram for explaining the limit depth values ​​for a vehicle traveling on a horizontal flooded road.

[0013] Figure 3 The figure is a diagram for explaining a situation in which a vehicle enters an area where it is likely to get stuck while traveling on a level road.

[0014] Figure 4 The figure is a diagram for explaining a situation in which a vehicle enters a flooded area while traveling on a sloping road.

[0015] Figure 5 This is a flowchart showing the operation of the vehicle travel control device when traveling in a bad road area according to one embodiment of the present invention.

[0016] Figure 6 yes Figure 5 The process of step S20 (departure from the travel control process) is a subroutine.

[0017] Explanation of symbols 1…Travel control device 10…Camera unit 11…Stereo Camera 11a…Main Camera 11b…Secondary camera 12…Image Processing Unit (IPU) 13…Image recognition unit 14…Control unit (M_ECU) 15… Bad road area entry judgment unit 16…Road surface μ estimation unit 17…Brake operation detection unit 18… Various sensors 19…Wheel speed sensor 20…Tilt angle sensor 21…CP_ECU 22…D / M_ECU 23…BK_ECU 31…Human Machine Interface (HMI) 31a…Notification device 32F...Front drive motor 32R…Rear drive motor 33…Brake actuator A, A1…Road slope B…The front end of the vehicle D, D2, D3…water depth D1…Limit depth value F…Direction of travel H…Camera setting height H1…The distance from the camera location to the flooded surface L1…Flooded noodles L2…Lower surface side of the base plate L3…Imaginary line connecting the front wheel rotation center and the rear wheel rotation center M, M1…Vehicle Ro…Road surface Ro1…Road surface with waterlogged slope Ro2…Slope road surface W…Flood W2…Flooded area WhF…Front wheel WhR…Rear wheel DETAILED DESCRIPTION Hereinafter, the present invention will be described by way of illustrated embodiments. The drawings used in the following description are schematically illustrated drawings. Therefore, in these drawings, each component is shown in a size that can be recognized on the drawings. Therefore, there is a situation where each component is shown in a different manner such as the dimensional relationship and / or scale of each component on the drawings. Therefore, the quantities, shapes, ratios of various sizes, relative positional relationships, etc. of each component recorded in the drawings of the present invention are not limited to the illustrated manner.

[0018] First, use Figure 1 Hereinafter, a schematic configuration of a vehicle travel control device according to an embodiment of the present invention will be described. Figure 1 It is a block diagram showing a schematic configuration of a vehicle travel control device according to one embodiment of the present invention.

[0019] It should be noted that Figure 1 The basic structure of the driving control device of the present embodiment shown in FIG. 1 is substantially the same as that of a conventional driving control device for a vehicle of the same type. Figure 1 In the following description, illustrations and detailed descriptions of common components in conventional vehicle travel control devices are omitted. In addition, only the main components directly related to the present invention are illustrated in the figure. Figure 1 And explained below.

[0020] A vehicle travel control device 1 according to the present embodiment includes a camera unit 10 which is a vehicle-mounted camera device including a stereo camera 11 fixed to a front upper center portion of a vehicle cabin (not shown) on which the travel control device 1 is mounted.

[0021] like Figure 1 As shown, the camera unit 10 is configured to include a stereo camera 11 and an image processing unit (Image Processing Unit; in Figure 1 12. Image recognition unit 13. Control unit (in Figure 1 "M_ECU") 14, etc.

[0022] The stereo camera 11 is formed to include two cameras, a main camera 11a and a sub-camera 11b. The main camera 11a and the sub-camera 11b are arranged, for example, in a vehicle compartment in a manner that they face the front of the vehicle at left-right symmetric positions sandwiching the center in the vehicle width direction. The main camera 11a and the sub-camera 11b are each composed of, for example, an imaging optical system, an imaging element such as a CMOS image sensor, and a processing circuit for processing imaging signals, etc. (the detailed configuration is omitted in the figure).

[0023] With such a configuration, the stereo camera 11 uses the main camera 11a and the auxiliary camera 11b to obtain two image data from two different viewpoints with the surrounding environment of a predetermined range in front of the vehicle as the object in a predetermined shooting cycle synchronized with each other. Then, stereo image data is generated based on the two image data thus obtained. The stereo image data is surrounding environment information representing the surrounding environment during the driving process of the vehicle. The surrounding environment information (image data) generated in the stereo camera 11 is output to the image processing unit 12.

[0024] The image processing unit 12 is a component or circuit unit that performs predetermined image processing on the surrounding environment information (image data representing the surrounding environment during the vehicle's travel) acquired by the stereo camera 11. The image processing unit 12 performs processing to detect the edges of various objects (objects or dividing lines, etc.) displayed on the image, for example.

[0025] The image processing unit 12 acquires distance information based on the positional deviation of the corresponding edges on the left and right images based on the stereoscopic image data, and generates image information (distance image information) including the distance information. The distance image information generated by the image processing unit 12 is output to the image recognition unit 13.

[0026] The image recognition unit 13 calculates the road curvature [1 / m] of the left and right dividing lines of the driving path (the driving path of the vehicle) and the width between the left and right dividing lines (lane width) based on the distance image information received from the image processing unit 12. The road curvature and lane width are obtained by various known methods.

[0027] In addition, the image recognition unit 13 performs predetermined pattern matching based on the distance image information generated by the image processing unit 12, and recognizes three-dimensional objects extending along the road (such as guardrails and / or curbstones and other surrounding vehicles, etc.), parking frame lines marked by dividing lines on the road surface of a building such as a parking lot, or three-dimensional structures such as a barrier that sets a parking division area, or a gap space between other adjacent vehicles, etc. In addition, the condition of the road surface or ground (hereinafter referred to as the wheel contact surface) around the vehicle (hereinafter referred to as the road surface condition, etc.) is also recognized.

[0028] Here, in the recognition of three-dimensional objects (object recognition) in the image recognition unit 13, for example, the type of the three-dimensional object, the height of the three-dimensional object, the width of the three-dimensional object, the distance from the vehicle to the three-dimensional object, the moving speed of the three-dimensional object, the relative speed between the three-dimensional object and the vehicle, the relative distance between the three-dimensional objects (for example, the lateral distance between the curbstone at the edge of the road and the dividing line located near it, etc.) are recognized.

[0029] In addition, the road conditions recognized by the image recognition unit 13 include, for example, a general recognition of a paved road or an unpaved road, or rough terrain, recognition of detailed conditions when the road is recognized as an unpaved road or rough terrain (for example, muddy, sandy, or snowy), or recognition of a flooded road (underpass, etc.), or accumulation of water, mud, or snow (hereinafter referred to as accumulation of water, etc.) in an unpaved road or rough terrain.

[0030] Here, areas with water accumulation on unpaved roads or rough ground can be considered areas where vehicles are prone to get stuck. Therefore, in the following description, such areas are referred to as areas where vehicles are prone to get stuck. The road conditions in these areas can be estimated based on, for example, brightness differences in images.

[0031] Various information recognized in the image recognition unit 13 is output as surrounding environment information to the control unit 14. In this case, the camera unit 10 including the image recognition unit 13 has a function as a surrounding environment recognition device that recognizes the surrounding environment of the vehicle.

[0032] The control unit 14 included in the camera unit 10 is a component unit or a circuit unit that controls the camera unit 10 and centrally controls the entire travel control device 1 of the present embodiment.

[0033] The control unit 14 is connected to various control units such as a driver seat control unit (CP_ECU) 21 , a drive motor control unit (D / M_ECU) 22 , and a brake control unit (BK_ECU) 23 via an in-vehicle communication line such as a CAN (Controller Area Network) 40 .

[0034] The CP_ECU 21 is connected to a human-machine interface (in Figure 1 The HMI 31 is described as “HMI” in the figure) 31. The HMI 31 is configured to include various notification devices 31a and the like in addition to various operation members, various sensing devices (not shown), and the like.

[0035] Here, as the various operating members, for example, there are a plurality of operating switches for instructing execution or stop of various driving assist controls and / or a mode switching switch for switching a driving mode.

[0036] In addition, various sensing devices include a steering wheel touch sensor that detects the driver's grip state, a driver monitoring system (DMS) that detects the driver's facial recognition and / or line of sight, and an in-vehicle monitoring system composed of an in-vehicle camera that recognizes the riding status of people including the driver.

[0037] In addition, as various notification devices 31 a , there are touch panel type display devices (visual display devices), sound generation devices including speakers and the like (auditory display devices), combination meters in which various measuring instruments are integrated, and the like.

[0038] CP_ECU21 is a component unit or circuit unit that, upon receiving a control signal from the control unit 14, uses the notification device 31a included in the HMI31 to appropriately notify the driver of various information (such as the implementation status of various alarms and / or driving assistance controls and various information related to the surrounding environment of the vehicle, etc.) in a predetermined manner (visual or auditory display).

[0039] Furthermore, the CP_ECU 21 outputs various input information such as instruction signals input by the driver using various operation members included in the HMI 31 (for example, on / off instructions for various driving assistance controls) to the control unit 14 .

[0040] The output side of the D / M_ECU 22 is connected to a drive motor ( 32F, 32R) or the like as a drive source of the vehicle. In addition, the input side of the D / M_ECU 22 is connected to various sensors such as an accelerator sensor (not shown).

[0041] Here, as the driving motor, there are a front driving motor 32F and a rear driving motor 32R. The front driving motor 32F is a driving source for driving the front wheels via the front axle, and the rear driving motor 32R is a driving source for driving the rear wheels via the rear axle.

[0042] The D / M_ECU 22 is a component or circuit unit that performs drive control of the two drive motors (32F, 32R) based on control signals from the control unit 14 or detection signals from various sensors. In addition, the D / M_ECU 22 outputs signals such as the accelerator opening detected by various sensors to the control unit 14.

[0043] Here, the D / M_ECU 22, the drive motors (32F, 32R), and the various sensors (accelerator sensor, etc.) described above constitute a driving force control device, which independently drives and controls the front wheels and the rear wheels.

[0044] The output side of the BK_ECU 23 is connected to a brake actuator 33 (at Figure 1The brake actuator 33 is an actuator for adjusting the hydraulic pressure of the brake fluid output to the pistons in the brake cylinders or the pistons in the brake calipers (not shown) included in the brake devices provided at the front and rear wheels, respectively. In addition, various sensors such as a brake pedal sensor, a yaw rate sensor, a front and rear acceleration sensor, and a vehicle speed sensor (not shown) are connected to the input side of the BK_ECU 23.

[0045] BK_ECU23 is a component unit or circuit unit that performs driving control of the brake actuator 33 based on the control signal from the control unit 14 or the detection signal from various sensors to perform braking control of the vehicle. Thus, BK_ECU23 causes each wheel to appropriately generate a braking force for performing mandatory braking control and / or yaw rate control on the vehicle. In addition, BK_ECU23 outputs signals of the brake operation state, yaw rate, front and rear acceleration, vehicle speed (vehicle speed), etc. detected by various sensors to the control unit 14. Here, the brake control device is composed of BK_ECU23, the brake actuator 33, and the above-mentioned various sensors (brake pedal sensor, etc.).

[0046] In addition, various sensors 18, a wheel speed sensor 19, and a tilt angle sensor 20 are connected to the control unit 14. Here, although not shown in the figure, the various sensors 18 include, for example, a positioning unit, a vehicle-mounted radar device, a rear image sensor, a LiDAR (Light Detection And Ranging) device, a near-infrared sensor, an external temperature sensor, and the like.

[0047] The wheel speed sensor 19 is a wheel speed detection sensor that detects the wheel rotation speed by detecting a pulse signal (wheel speed pulse) generated in proportion to the rotation speed of each wheel in the vehicle. The vehicle speed can be detected based on the wheel speed data of each wheel acquired by the wheel speed sensor 19.

[0048] The tilt angle sensor 20 is a slope detection sensor that detects the slope of the wheel contact surface on the road surface (ground) (hereinafter referred to as road surface slope, etc.) by detecting the inclination of the vehicle in the front-rear direction with respect to the horizontal.

[0049] The control unit 14 performs driving control of the vehicle based on various information acquired by the camera unit 10 and various sensors 18, the wheel speed sensor 19, the tilt angle sensor 20, etc. The driving control in this case is, for example, the driving control of the vehicle as required, including at least brake control (Brake control) of each wheel by the BK_ECU 23, in addition to the output control of the drive motor (32F, 32R) and / or the torque distribution control of each drive wheel by the D / M_ECU 22.

[0050] Furthermore, the control unit 14 internally includes a bad road area entry determination unit 15 , a road surface μ estimation unit 16 , a brake operation detection unit 17 , and the like.

[0051] The bad road area entry determination unit 15 is a component unit or a circuit unit that determines whether the vehicle has entered a bad road area based on various information acquired by the camera unit 10 , various sensors 18 , wheel speed sensor 19 , and the like.

[0052] For example, the bad road area entry determination unit 15 detects the idling condition or deceleration change of the front wheels or the rear wheels based on the detection value of the rotation angle of the drive motors 32F, 32R relative to the drive control signal output from the D / M_ECU22 to the drive motors 32F, 32R, or the detection value of each wheel speed sensor 19 corresponding to the front wheels or the rear wheels, thereby determining whether the vehicle has entered the bad road area.

[0053] The bad road area entry determination unit 15 determines entry into a bad road area by distinguishing paved roads, unpaved roads, or rough ground, for example, based on the brightness difference of the wheel contact surface obtained from the image data captured by the stereo camera 11 .

[0054] In this case, when the road surface is identified as an unpaved road or rough ground, the road surface type such as muddy, sandy, or snowy may be identified.

[0055] Furthermore, the condition of the traveled route can be considered to identify areas where the vehicle is likely to get stuck, such as flooded roads (underpasses, etc.), unpaved roads, or rough terrain.

[0056] The road surface μ estimating unit 16 is a component or circuit unit that estimates the friction coefficient of the wheel contact surface (hereinafter referred to as road surface μ) based on various information acquired by the camera unit 10 , various sensors 18 , wheel speed sensor 19 , and the like.

[0057] For example, the road surface μ estimation unit 16 detects the idling of the front wheels or the rear wheels based on the detection value of the rotation angle of the drive motors 32F, 32R relative to the drive control signal output from the D / M_ECU22 to the drive motors 32F, 32R, or the detection value of each wheel speed sensor 19 corresponding to the front wheels or the rear wheels, thereby estimating the road surface μ.

[0058] In this case, the road surface μ estimating unit 16 may further refer to information related to the road surface condition recognized by the image recognition unit 13, detection values ​​of the near infrared sensor and the outside air temperature sensor included in the various sensors 18, etc., when estimating the road surface μ.

[0059] Furthermore, the road surface μ estimating unit 16 may identify a paved road, an unpaved road, or a rough surface based on, for example, a brightness difference of the wheel contact surface obtained from image data captured by the stereo camera 11 as an auxiliary reference for road surface μ estimation.

[0060] In this case, when the road surface is identified as an unpaved road or rough ground, detailed identification such as muddy ground, sandy ground, or snow can be further performed as an auxiliary reference for road surface μ estimation.

[0061] Furthermore, it is possible to identify areas where vehicles are prone to getting stuck, such as flooded roads (underpasses, etc.), unpaved roads, or rough terrain, as an auxiliary basis for estimating the road surface μ.

[0062] Furthermore, the road surface μ estimating unit 16 may, for example, serve as a determination auxiliary criterion for making the road surface μ high when the outside temperature is equal to or higher than a predetermined threshold, or may serve as a determination auxiliary criterion for making the road surface μ low when the outside temperature is lower than the predetermined threshold.

[0063] The brake operation detector 17 is a component or circuit unit that detects whether a brake operation is performed by the driver, such as stepping on the brake pedal. The brake operation detector 17 detects the execution of the brake operation by receiving a predetermined output signal from the brake control device, that is, an output signal from a brake pedal sensor transmitted via the BK_ECU 23 .

[0064] It should be noted that all or part of the image recognition unit 13, control unit 14, bad road area entry determination unit 15, road surface μ estimation unit 16, brake operation detection unit 17, CP_ECU21, D / M_ECU22, BK_ECU23, etc. are composed of a processor including hardware.

[0065] Here, the processor, for example, is composed of a known structure including a non-transitory computer readable medium (non-transitory computer readable medium) and its peripheral devices in addition to a central processing unit (CPU), RAM (Random Access Memory), ROM (Read Only Memory), a non-volatile memory, a non-volatile storage device, etc.

[0066] Software programs executed by the CPU and / or fixed data such as data tables are stored in advance in the ROM, nonvolatile memory, nonvolatile storage device, etc. The CPU reads the software program stored in the ROM, etc. and expands it to the RAM for execution. In addition, the software program appropriately refers to various data, etc., thereby realizing the functions of the above-mentioned components, components (13 to 17, 21 to 23), etc.

[0067] In addition, the processor may be formed of a semiconductor chip such as an FPGA (Field Programmable Gate Array). In addition, each of the above-mentioned components, components (13 to 17, 21 to 23), etc. may be formed of an electronic circuit.

[0068] In addition, as a computer program product, the software program may be recorded in whole or in part on a non-transitory computer readable medium such as a portable plate-type medium such as a floppy disk, CD-ROM, DVD-ROM, a card-type memory, an HDD (Hard Disk Drive) device, an SSD (Solid State Drive) device, etc.

[0069] Generally, in vehicles such as automobiles, for example, an upper limit value of the depth at which the vehicle will not be submerged in water and can ensure safe and reliable driving (hereinafter referred to as a limit depth value) is set for each vehicle. This limit depth value is not only referred to when entering an area of ​​water, but also is referred to as an upper limit value of the depth at which the driving force of the driving wheels can be reliably transmitted to the road surface when the vehicle enters an area of ​​mud, snow, etc.

[0070] For example, when a vehicle enters a flooded area, if the vehicle exceeds a predetermined limit depth and sinks in the water, the vehicle may become unable to drive due to, for example, electrical system components of the vehicle being submerged in the water.

[0071] In addition, for example, when a vehicle enters a muddy or snowy area where the vehicle is prone to getting stuck, if the vehicle exceeds a predetermined limit depth value and enters the muddy or snowy area, for example, the lower surface side of the vehicle floor may come into contact with the ground (muddy upper surface or snowy upper surface, etc.). In this case, there is a possibility that the wheels cannot ensure a sufficient contact state with the wheel contact surface, or even if the wheels are in contact, the low μ of the road surface may cause the drive wheels to spin idly, which is a so-called stuck state.

[0072] Here, use Figure 2 The limit depth values ​​for the vehicle are described below. Figure 2 This is a diagram illustrating the limit depth value of a vehicle traveling on a horizontal flooded road.

[0073] As the limit depth value generally prescribed in a vehicle, for example, the following general criteria are prescribed.

[0074] For example, Figure 2 The vehicle M is shown to be stationary or traveling on a horizontal road surface Ro. At this time, the road surface Ro is flooded as indicated by a symbol W. Furthermore, a symbol D indicates the depth of the flood W at this time.

[0075] It should be noted that in Figure 2 In the example of FIG. 1 , the water depth D of the flood W is shown to reach a predetermined limit depth value D1 . Therefore, in the following description, it is assumed that the predetermined limit depth value D1 of the vehicle M=the water depth D.

[0076] In addition, Figure 2 The symbol M in the middle shows a vehicle. The symbol WhF shows the front wheels of the vehicle M, and the symbol WhR shows the rear wheels of the vehicle M. The vehicle M includes a camera unit 10. The camera unit 10 is fixed to the front upper center portion of the vehicle M's cabin.

[0077] In addition, Figure 2 In the figure, reference numeral L1 indicates a flooded surface of the flood W. Reference numeral L2 indicates a lower surface side of a floor of the vehicle M. Reference numeral L3 indicates an imaginary straight line connecting the rotation center of the front wheel WhF of the vehicle M and the rotation center of the rear wheel WhR.

[0078] for Figure 2As for the limit depth value D1 specified in the vehicle M shown, it is expected to be set to, for example, a depth below the radius of the wheel (WhF, WhR) (L3≥D1), or to a degree at which the lower surface side L2 of the floor of the vehicle M does not contact the flooded surface L1 (or a muddy surface or a snowy surface, etc.) (L2≥D1).

[0079] exist Figure 2 In the illustrated situation (ie, the situation in which the vehicle M is on the horizontal road surface Ro), the camera unit 10 of the vehicle M can obtain the water depth D of the flood W based on the acquired image data.

[0080] Therefore, first, the distance from the installation position of the camera unit 10 to the flooded surface L1 is detected (refer to Figure 2 symbol H1). Here, Figure 2 The symbol H in represents the camera installation height of the camera unit 10. That is, the camera installation height H is the distance from the installation position of the camera unit 10 to the point where a straight line extending from the installation position of the camera unit 10 toward the road surface Ro in the vertical direction intersects the road surface Ro. The camera installation height H is a predetermined value specified for each vehicle.

[0081] Therefore, in Figure 2 The water depth D in the illustrated condition (the vehicle M is in a horizontal condition) can be obtained from the distance H1 detected based on the image data of the camera unit 10 and a predetermined camera installation height H (D=H−H1).

[0082] Therefore, in Figure 2 In the condition shown (vehicle M is in a horizontal state), by detecting the water depth D by the camera unit 10 while driving, when the vehicle M is about to exceed the limit depth value D1, appropriate braking control or driving force control can be performed to avoid sinking into water or getting stuck.

[0083] It should be noted that the limit depth value D1 of the vehicle M refers to, for example, the length from the surface where the front wheels WhF contact the road surface Ro to the flooded surface L1 on a straight line passing through the rotation center of the front wheels WhF of the vehicle M.

[0084] However, when the vehicle M enters a water-logged area where it is easy to get stuck (see Figure 3 ), or the vehicle M is traveling on a sloped road and enters a flooded area (refer to Figure 4 ) and cannot be directly applied to Figure 2 In the illustrated situation (the vehicle M is level), a limit depth value D1 is specified.

[0085] For example, Figure 3As shown, let us consider the situation where a vehicle M enters a pool of water W1 having a road slope A while traveling on a horizontal road. Figure 3 In FIG. 1 , symbol M indicates a vehicle traveling on a horizontal road surface Ro. Figure 3 The symbol D1 shows the limit depth value of the vehicle M in this state (horizontal state). The arrow symbol F shows the traveling direction of the vehicle M.

[0086] In addition, Figure 3 The middle symbol M1 shows a part of the vehicle when the front wheel WhF enters the water W1 after the vehicle M travels in the travel direction F. Here, only the front half of the vehicle M1 is shown, and the rear half is omitted. In addition, the symbol Ro shows the road surface of the horizontal part, and the symbol Ro1 shows the road surface of the water W1 part with the road surface slope A.

[0087] In this case, if Figure 3 As shown, the front wheel WhF of the vehicle M1 enters the position of the water depth D2. The water depth D2 at this time is less than the limit depth value D1 when it is horizontal (D1>D2). However, at this time point (position of the vehicle M1), the front end of the vehicle M1 (see symbol B) is about to be submerged in the water. Therefore, the water depth D2 at this time point can be called the limit depth value of the vehicle M1 in this situation.

[0088] In this way, the limit depth value (D2) of the vehicle M1 when entering the accumulated water W1 having the road surface gradient A is smaller than the limit depth value D1 of the vehicle M in the horizontal state (D1>D2).

[0089] In addition, for example, Figure 4 As shown, let us consider the situation where a vehicle M is traveling on a road with a road slope A1 and enters a flooded portion W2. Figure 4 In the figure, symbol M indicates a vehicle traveling on a road surface Ro2 having a road surface slope A1. Symbol D1 indicates a limit depth value when the vehicle M is in a horizontal state. Symbol W2 indicates a flooded portion. Figure 4 The situation shown assumes a situation when the paved road (road surface Ro2) enters a flooded portion W2 such as an underpass.

[0090] In this case, if Figure 4 As shown in FIG. 1 , the front wheel WhF of the vehicle M enters the position of the water depth D3. The water depth D3 at this time is less than the limit depth value D1 when it is horizontal (D1>D3). However, at this time point (the time point when the front wheel WhF enters the position of the water depth D3), the front end portion B of the vehicle M is about to be submerged in the water. Therefore, the water depth D3 at this time point can be called the limit depth value of the vehicle M in this situation.

[0091] Thus, the limit depth value D3 of the vehicle M when traveling on the road surface Ro2 having the road surface gradient A1 and entering the flooded portion W2 is smaller than the limit depth value D1 of the vehicle M in the horizontal state ( D1 > D3 ).

[0092] Thus, in the case where the vehicle M enters a water-logged area where it is easy to get stuck (see Figure 3 ), or vehicle M enters a flooded area from a sloping road (refer to Figure 4 ) under the condition that the vehicle M is traveling in a horizontal state (refer to Figure 2 ) is used to make a predetermined correction to the limit depth value under the condition of the vehicle. Furthermore, the predetermined correction to the limit depth value in this case can be predetermined according to the driving condition of the vehicle and the road surface slope.

[0093] And, if according to the driving conditions of the vehicle, for example: (1) Driving on a level road surface ( Figure 2 status), (2) When entering a sloping area where the vehicle is prone to getting stuck from a level road ( Figure 3 status), (3) When driving on a sloped road and entering a flooded area ( Figure 4 It is very convenient to prepare a correction map for the limit depth value according to the situation of the road surface gradient, etc. In this case, it is sufficient to specify a correction value corresponding to the road surface gradient for each situation.

[0094] Next, use Figure 5 The following describes the travel control of the vehicle M during travel in a bad road area in the operation of the travel control device 1 according to one embodiment of the present invention. Figure 5 This is a flowchart showing a part of the operation of the vehicle travel control device according to one embodiment of the present invention, that is, travel control when traveling in a bad road area.

[0095] First, a vehicle M equipped with the driving control device 1 of the present embodiment drives forward on a road or the like. Here, in the case of a road or the like, in addition to general public roads, private roads, etc., it also includes areas other than general roads, such as camping sites or river lands, etc., in public or private lands. And, when the vehicle M is driving, the driving control device 1 of the present embodiment mounted on the vehicle M is in an activated state.

[0096] When the vehicle M is in this state, Figure 5In step S1, the control unit 14 performs a surrounding environment recognition process for recognizing the surrounding environment of the vehicle M and the state of the vehicle M based on output data from the camera unit 10 and various sensors 18, the wheel speed sensor 19, the inclination angle sensor 20, etc. The surrounding environment recognition process is continuously performed while the travel control device 1 of the vehicle M is in the activated state.

[0097] In step S2 , the bad road area entry determination unit 15 of the control unit 14 determines whether the vehicle M has entered the bad road area based on the information acquired in the process of step S1 described above.

[0098] Here, the bad road area refers to an area with road conditions such as an unpaved road other than a paved road or an area with rough ground where a vehicle may easily get stuck.

[0099] The bad road area entry judgment of the vehicle M here is performed by, for example, detecting the brightness difference of the wheel contact surface around the vehicle M based on the image data captured by the stereo camera 11 of the camera unit 10, and performing the judgment based on the detection result. In addition, for example, based on the wheel speed data of each wheel (four wheels) of the vehicle M acquired by the wheel speed sensor 19, the change of each wheel speed is detected, and the bad road area entry judgment is performed based on the detection result.

[0100] In the process of step S2, if it is determined that the vehicle has entered the bad road area, the process proceeds to the next step S3. On the other hand, if it is not confirmed that the vehicle has entered the bad road area, the process returns to step S1 and the subsequent processes are repeated.

[0101] In step S3 , the control unit 14 receives output data from the inclination angle sensor 20 to detect the road surface gradient.

[0102] Next, in step S4 , the control unit 14 estimates the road surface μ of the wheel contact patch around the vehicle M in the road surface μ estimating unit 16 based on output data from the camera unit 10 , various sensors 18 , wheel speed sensor 19 , and the like.

[0103] Next, in step S5, the control unit 14 refers to the road surface gradient information (detected in the process of step S3) and the road surface μ information (estimated in the process of step S4) to confirm whether the road surface gradient is greater than a predetermined threshold value and whether the estimated road surface μ is lower than a predetermined threshold value. Here, if the road surface gradient is large and the estimated road surface μ is low, the process proceeds to the next step S6. In addition, in cases other than "the road surface gradient is large" and "the estimated road surface μ is low", the process proceeds to step S7.

[0104] In step S6, the bad road area entry determination unit 15 of the control unit 14 confirms whether all wheels are about to enter the area where the vehicle is likely to get stuck or whether the limit depth value is about to be reached based on the output data from the camera unit 10, various sensors 18, wheel speed sensor 19, etc. Here, in either case of all wheels about to enter or about to reach the limit depth value, the process proceeds to step S8. In addition, if it is not any of the cases, the process returns to step S1 and the subsequent processes are repeated.

[0105] On the other hand, in step S7, the bad road area entry determination unit 15 of the control unit 14 checks whether the limit depth value is about to be reached based on the output data from the camera unit 10, various sensors 18, wheel speed sensor 19, etc. Here, if the limit depth value is about to be reached, the process proceeds to step S8. On the other hand, if the limit depth value is not about to be reached, the process returns to step S1 and the subsequent processes are repeated.

[0106] In step S8, the control unit 14 uses the notification device 31a to execute a first notification process. The notification content in the first notification process is, for example, a warning notification such as "If you continue to move forward, you may get stuck."

[0107] Next, in step S9, the control unit 14 detects whether the driver has performed a brake operation in the brake operation detection unit 17. Here, the brake operation performed by the driver can be detected by detecting an output signal of a brake pedal sensor (not shown).

[0108] In the process of step S9, if the brake operation by the driver is not detected, the process proceeds to step S10. On the other hand, if the brake operation by the driver is detected, the process proceeds to step S12.

[0109] In step S10, the control unit 14 controls the brake actuator 33 through the BK_ECU 23 to execute a predetermined automatic deceleration control process. The automatic deceleration control is a braking control based on the brake control device (BK_ECU 23, etc.), and is a first avoidance control to prevent the vehicle M from entering an area in the bad road area where the vehicle is prone to getting stuck.

[0110] Next, in step S11, the control unit 14 uses the notification device 31a to perform a second notification process. The notification content in the second notification process is, for example, a warning notification such as "After the automatic stop, the vehicle will move backward. Please do not press the brake pedal with your foot." Thereafter, the process proceeds to step S20.

[0111] On the other hand, in the process of step S9 described above, if the brake operation performed by the driver is detected and the process proceeds to step S12, then in step S12, the control unit 14 uses the notification device 31a to perform a third notification process. The notification content in the third notification process is, for example, a warning notification such as "Going backward. Please take your foot off the brake pedal." Thereafter, the process proceeds to step S20.

[0112] In step S20, the control unit 14 executes a predetermined disengagement travel control process. The disengagement travel control is a drive control based on the driving force control device (D / M_ECU 22, etc.) to prevent the vehicle M from entering an area in the bad road area where the vehicle is likely to get stuck and to perform a second avoidance control to disengage from the area.

[0113] Figure 6 This is a subroutine for disengaging from the travel control process.

[0114] exist Figure 6 In step S21, the bad road area entry determination unit 15 of the control unit 14 refers to the road surface gradient information (detected in the process of step S3) and the road surface μ information (estimated in the process of step S4) to confirm whether the road surface gradient is greater than a predetermined threshold value and whether the estimated road surface μ is lower than a predetermined threshold value. Here, if the road surface gradient is large and the estimated road surface μ is low, the process proceeds to the next step S22. In addition, in cases other than "the road surface gradient is large" and "the estimated road surface μ is low", the process proceeds to step S23.

[0115] In step S22 , the control unit 14 controls the drive motors 32F and 32R through the D / M_ECU 22 to execute reverse running control of the drive distribution control in which the rear wheels are driven primarily and the front wheels are driven less.

[0116] The situation at this time is as described above, "the road surface slope is large" and "the estimated road surface μ is low". In addition, at this time, the front wheels enter the area where the vehicle is prone to getting stuck, but the rear wheels have not yet entered the area where the vehicle is prone to getting stuck. Therefore, it is considered that in this situation, it is easy to get out of this situation by performing drive distribution control that mainly applies drive force to the rear wheels. Therefore, in the processing of this step S22, while the rear wheels are mainly driven, the front wheels are driven to suppress the transmission of drive force. It should be noted that at this time, when the vehicle M is made to get out of this situation, it is based on the reverse driving control. Thereafter, the process returns to the original process (return).

[0117] In step S23 , the control unit 14 controls the drive motors 32F and 32R through the D / M_ECU 22 to drive all wheels to perform reverse travel control. Thereafter, the process returns to the original process (return).

[0118] As described above, according to the above embodiment, if it is detected that the vehicle M is about to enter an area where the vehicle is likely to get stuck, such as water, mud, or snow, while traveling in a bad road area, the vehicle M is decelerated or stopped before the vehicle M reaches the limit depth value. In this case, first, the notification device 31a is used to make a first notification to the driver to prompt a braking operation or perform automatic braking control, thereby preventing the vehicle from entering an area where the vehicle is likely to get stuck (first avoidance control).

[0119] In this case, the timing of suppressing entry into the area where the vehicle is likely to get stuck is different depending on the road surface gradient and the estimated road surface μ. When the road surface gradient is large and the estimated road surface μ is low, the first avoidance control is performed before all wheels enter the area where the vehicle is likely to get stuck. In other cases, the first avoidance control is performed before the limit depth value is reached. This control is an improvement made in consideration of the fact that the greater the road surface gradient and the lower the estimated road surface μ, the more difficult it is to escape from the area where the vehicle is likely to get stuck. That is, the escape control is performed at a stage before all wheels enter the area where the vehicle is likely to get stuck.

[0120] In this way, after the vehicle M is stopped by deceleration control before entering an area where the vehicle is likely to get stuck, the reverse driving control is performed to escape from the area where the vehicle is likely to get stuck. In this case, the driving force distribution between the rear wheels and the front wheels during reverse driving is appropriately changed according to the road slope and the estimated road surface μ, so that the vehicle can escape smoothly and reliably.

[0121] Specifically, when the road surface gradient is large and the estimated road surface μ is low, the rear wheels are driven primarily and the front wheels are suppressed, and the reverse travel control is performed. In other cases, the reverse travel control is performed to drive all wheels.

[0122] By executing such travel control, it is possible to avoid the vehicle M from being submerged in water or getting stuck.

[0123] The present invention is not limited to the above-mentioned embodiments, and it is obvious that various modifications and applications can be implemented within the scope of the main purpose of the invention. In addition, the above-mentioned embodiments include inventions of various stages, and various inventions can be extracted by appropriate combinations of the disclosed multiple constituent elements. For example, even if a few constituent elements are deleted from all the constituent elements shown in the above-mentioned embodiment, the technical problem can be solved and the technical effect can be obtained, and the structure with the deleted constituent elements can be extracted as an invention. In addition, the constituent elements in different embodiments can be appropriately combined. The present invention is not limited by its specific embodiment except as limited by the attached claims.

Claims

1. A vehicle travel control device, characterized in that: have: A surrounding environment recognition device, which obtains the surrounding environment information of the vehicle; a brake control device for performing brake control of the vehicle; A driving force control device that independently drives and controls the front wheels and the rear wheels; as well as a control unit including at least a bad road area entry determination unit for determining that the vehicle enters a bad road area and a road surface μ estimation unit for estimating a friction coefficient of a wheel contact surface, The control unit executes the first avoidance control and then executes the second avoidance control when it is determined that the vehicle is about to enter an area in the bad road area where the vehicle is likely to get stuck, based on the determination result obtained by the bad road area entry determination unit.

2. The vehicle travel control device according to claim 1, characterized in that: The first avoidance control is based on the braking control performed by the braking control device, The second avoidance control is a drive control performed by the drive force control device.

3. The vehicle travel control device according to claim 1, characterized in that: The vehicle travel control device further includes a notification device, and The control unit further includes a brake operation detection unit for detecting a brake operation performed by a driver. When the control unit determines that the vehicle is about to enter an area in the bad road area where the vehicle is likely to get stuck based on the determination result obtained by the bad road area entry determination unit, and detects a braking operation performed by the driver based on the detection result obtained by the braking operation detection unit, The second avoidance control is executed after the warning notification is performed by the notification device.

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