Travel control apparatus for vehicle

Abstract

To provide a travel control apparatus for a vehicle, for executing travel control which enables a vehicle, such as an automobile, to avoid being submerged or getting stuck, for example.SOLUTION: A travel control apparatus for a vehicle includes: a surrounding environment recognition device 10 for acquiring surrounding environment information of a vehicle M; brake control devices (23, 33) for performing brake control of the vehicle; driving force control devices (22, 32F, 32R) for performing drive control of front wheels and rear wheels individually; and a control unit 14 including at least a rough road area entry determination section 15 for determining entry of the vehicle into a rough road area, and a road surface μ estimation section 16 for estimating a friction coefficient of a wheel ground contact surface. The control unit executes first avoidance control and then executes second avoidance control when determining that the vehicle is likely to enter an area, in the rough road area where the vehicle easily gets stuck, on the basis of a determination result by the rough road area entry determination section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle driving control device that can execute driving control in a vehicle such as an automobile to prevent the vehicle from becoming submerged in water or getting stuck while driving on a rough road, for example. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in vehicles such as automobiles, for example, in common types of four-wheeled automobiles, so-called all-wheel drive vehicles equipped with a structure capable of driving all wheels, both front and rear (usually all four wheels), have been put into practical use and are widely used.

[0003] This type of all-wheel drive vehicle is generally highly capable of traveling on rough roads, and is therefore expected to be widely used in various driving environments. For example, when traveling on unpaved roads and other areas called rough roads, the vehicle may enter an area with puddles, mud, snow, etc. In this case, the vehicle may become submerged in water and become unable to travel, or the drive wheels may spin, resulting in a so-called stuck state.

[0004] In such a situation, if the vehicle is about to become stuck, if the vehicle is an all-wheel drive type, even if the front wheels are stuck in the mud, the driving force of the rear wheels may be able to pull the vehicle out of the mud. However, if more driving force than necessary is applied to the front wheels at this time, the front wheels will spin, which may cause the vehicle to become stuck even deeper.

[0005] In view of this, various technologies have been proposed in the past, for example in JP 2009-78592 A, for driving control devices that perform drive control to switch driving force at the appropriate time in an all-wheel drive vehicle to extricate the vehicle from a stuck state. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-78592 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, there are cases where the vehicle cannot necessarily be reliably extricated from a stuck state by only the control using the conventional driving control device disclosed in the above-mentioned JP 2009-78592 A or the like.

[0008] Therefore, when a vehicle is driven on a rough road, it is desirable to drive the vehicle while avoiding entering areas where there are puddles, mud, or snow.

[0009] An object of the present invention is to provide a vehicle driving control device capable of executing driving control in a vehicle such as an automobile that can avoid submersion in water or getting stuck while driving on a rough road, for example. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, a vehicle driving control device of one embodiment of the present invention comprises a surrounding environment recognition device that acquires surrounding environment information of the vehicle, a braking control device that performs braking control of the vehicle, a driving force control device that separately drives and controls the front wheels and rear wheels, a control unit that includes at least a rough road area entry judgment unit that judges whether the vehicle is entering a rough road area, and a road surface μ estimation unit that estimates the friction coefficient of the wheel contact surface, and when the control unit judges, based on the judgment result by the rough road area entry judgment unit, that the vehicle is likely to enter an area in the rough road area where it is easy to get stuck, it executes a first avoidance control and then executes a second avoidance control. Effect of the Invention

[0011] According to the present invention, it is possible to provide a vehicle driving control device that can execute driving control in a vehicle such as an automobile to prevent the vehicle from becoming submerged in water or getting stuck while driving on a rough road, for example. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a vehicle driving control device according to an embodiment of the present invention; [Diagram 2] An illustration of the limit depth value for a vehicle traveling on a horizontal flooded road. [Diagram 3] FIG. 1 is a diagram illustrating a situation in which a vehicle enters an area where it is likely to get stuck while traveling on a level road; [Figure 4] A diagram illustrating a situation in which a vehicle is traveling on a sloped road and enters a flooded area. [Diagram 5] 1 is a flowchart showing a driving control when the vehicle is traveling on a rough road area, among the operations of the vehicle driving control device according to an embodiment of the present invention; [Figure 6] 6 is a subroutine of the process of step S20 in FIG. 5 (escape travel control process). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described below with reference to the illustrated embodiments. The drawings used in the following description are schematic. Therefore, in these drawings, each component is shown at a size that allows it to be recognized on the drawing. For this reason, the dimensional relationship and scale of each member on the drawing may be shown differently for each component. Therefore, the present invention is not limited to the illustrated forms with respect to the quantities, shapes, size ratios, relative positional relationships, etc. of each component shown in each drawing.

[0014] First, a schematic configuration of a vehicle cruise control device according to one embodiment of the present invention will be described below with reference to Fig. 1. Fig. 1 is a block diagram showing a schematic configuration of a vehicle cruise control device according to one embodiment of the present invention.

[0015] The basic configuration of the cruise control device of this embodiment shown in Fig. 1 is substantially the same as that of a conventional cruise control device for a vehicle of the same type. Therefore, in Fig. 1 and the following description, illustration and detailed description of general components in a cruise control device for a conventional vehicle are omitted. Only main components directly related to the present invention are illustrated in Fig. 1 and will be described below.

[0016] The vehicle cruise control device 1 of this embodiment has a camera unit 10 which is an in-vehicle camera device including a stereo camera 11 fixed to a front upper central portion of the interior of a vehicle (not shown) on which the cruise control device 1 is mounted.

[0017] As shown in FIG. 1, the camera unit 10 is configured to include a stereo camera 11, an image processing unit (referred to as "IPU" in FIG. 1) 12, an image recognition unit 13, and a control unit (referred to as "M_ECU" in FIG. 1) 14.

[0018] The stereo camera 11 is formed with 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 the vehicle cabin at symmetrical positions with respect to the center in the vehicle width direction, facing the front of the vehicle. Each of the main camera 11a and the sub camera 11b is composed of, for example, an imaging optical system, an imaging element such as a CMOS image sensor, and a processing circuit that processes imaging signals, etc. (detailed configuration is not shown).

[0019] With this configuration, the stereo camera 11 acquires two image data from two different viewpoints targeting a predetermined range of the surrounding environment in front of the vehicle using the main camera 11a and the sub camera 11b at a predetermined imaging period synchronized with each other. Then, stereo image data is generated based on the two image data acquired in this way. This stereo image data is surrounding environment information that represents the surrounding environment while the vehicle is traveling. The surrounding environment information (image data) generated by the stereo camera 11 is output to the image processing unit 12.

[0020] The image processing unit 12 is a configuration unit or circuit unit that performs predetermined image processing on the surrounding environment information (image data representing the surrounding environment while the vehicle is traveling) acquired by the stereo camera 11. The image processing unit 12 performs, for example, processing to detect edges of various objects (objects, lane markings, etc.) displayed on the image.

[0021] The image processing unit 12 also acquires distance information based on the amount of positional shift of corresponding edges on the left and right images based on the stereo image data, and generates image information including the distance information (distance image information). The distance image information generated in the image processing unit 12 is output to the image recognition unit 13.

[0022] The image recognition unit 13 calculates the road curvature [1 / m] of the left and right dividing lines of the road on which the vehicle is traveling (the vehicle's traveling path) and the width between the left and right dividing lines (lane width) based on the distance image information and the like input from the image processing unit 12. Various well-known means are used to calculate the road curvature and lane width.

[0023] Furthermore, the image recognition unit 13 performs predetermined pattern matching based on the distance image information acquired by the stereo camera 11 to recognize three-dimensional objects (such as guardrails, curbs, and other nearby vehicles) extending along the road, parking frame lines marked by dividing lines on the road surface of a parking lot or the like, three-dimensional structures such as car stops that define parking space areas, and gap spaces between adjacent vehicles, etc. In addition, the image recognition unit 13 also recognizes the conditions (hereinafter referred to as road surface conditions, etc.) of the road surface or ground (hereinafter referred to as wheel contact surface) around the vehicle.

[0024] Here, the recognition of three-dimensional objects (object recognition) in the image recognition unit 13 recognizes, for example, the type of three-dimensional object, the height of the three-dimensional object, the width dimension 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, and the relative distance between three-dimensional objects (for example, the lateral distance between a curb on the side of the road and a dividing line nearby).

[0025] In addition, the road surface conditions recognized by the image recognition unit 13 include, for example, a general identification of whether the road is paved, unpaved, or uneven ground, and when it is recognized as an unpaved road or uneven ground, an identification of the detailed condition (for example, muddy ground, sandy ground, or snow-covered ground), or an identification of whether the road is flooded (underpass, etc.) or whether it is a puddle, mud, or snow-covered ground on an unpaved road or uneven ground (hereinafter referred to as puddles, etc.).

[0026] Here, an area with puddles on an unpaved road or rough ground is an area where a vehicle is likely to get stuck. In the following description, such an area will be referred to as an area where a vehicle is likely to get stuck. These road surface conditions can be estimated based on, for example, the brightness difference of the image.

[0027] Various pieces of information recognized by the image recognition unit 13 are output as surrounding environment information to the control unit 14. In this case, the camera unit 10 including the image recognition unit 13 functions as a surrounding environment recognition device that recognizes the surrounding environment of the vehicle.

[0028] The control unit 14 included in the camera unit 10 is a configuration unit or circuit unit that controls the camera unit 10 and also centrally controls the entire driving control device 1 of this embodiment.

[0029] This control unit 14 is connected to various control units, such as a cockpit 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.

[0030] A human-machine interface (referred to as "HMI" in FIG. 1) 31 arranged around the driver's seat is connected to the CP_ECU 21. The HMI 31 is configured to include, for example, various operating members, various sensing devices (not shown), and various notification devices 31a.

[0031] Here, the various operating members include, for example, a plurality of operating switches for instructing execution or stop of various driving assistance controls, a mode change switch for changing driving modes, and the like.

[0032] In addition, various sensing devices include a steering touch sensor that detects the driver's steering state, a driver monitoring system (DMS) that detects the driver's facial recognition and line of sight, and an in-vehicle monitor system consisting of an in-vehicle camera that recognizes the riding status of passengers including the driver.

[0033] The various notification devices 31a include a touch panel display device (visual display device), a sound output device (auditory display device) including a speaker, etc., and a combination meter that combines various instruments.

[0034] The CP_ECU 21 is a structural unit or circuit unit that, upon receiving a control signal from the control unit 14, appropriately notifies the driver of various information (e.g., various alarms, various information regarding the implementation status of driving assistance control, and the vehicle's surrounding environment, etc.) in a predetermined form (visual or auditory display) using the notification device 31a included in the HMI 31.

[0035] In addition, the CP_ECU 21 outputs various input information such as instruction signals (eg, ON / OFF instructions for various driving assistance controls) input by the driver using various operating members included in the HMI 31 to the control unit 14.

[0036] The output side of the D / M_ECU 22 is connected to the drive motors (32F, 32R) which are drive sources for the vehicle, etc. Also, the input side of the D / M_ECU 22 is connected to various sensors such as an accelerator sensor (not shown).

[0037] Here, the drive motors are assumed to be a front drive motor 32F and a rear drive motor 32R. The front drive motor 32F is a drive source that drives the front wheels through the front axle. The rear drive motor 32R is a drive source that drives the rear wheels through the rear axle.

[0038] The D / M_ECU 22 is a configuration unit or circuit unit that controls the drive of the two drive motors (32F, 32R) based on control signals from the control unit 14 or detection signals from various sensors. The D / M_ECU 22 also outputs signals such as the accelerator opening degree detected by the various sensors to the control unit 14.

[0039] Here, the D / M_ECU 22, the drive motors (32F, 32R), and the various sensors (accelerator sensor, etc.) constitute a driving force control device. This driving force control device controls the driving of the front wheels and the rear wheels separately.

[0040] A brake actuator 33 (denoted as "BK_AC" in FIG. 1) is connected to the output side of the BK_ECU 23. The brake actuator 33 is an actuator for adjusting the hydraulic pressure of brake fluid output to a piston in a brake wheel cylinder or a piston in a brake caliper (not shown) included in a brake device provided on each of the front and rear wheels. In addition, various sensors such as a brake pedal sensor, a yaw rate sensor, a longitudinal acceleration sensor, and a vehicle speed sensor (not shown) are connected to the input side of the BK_ECU 23.

[0041] The BK_ECU 23 is a configuration unit or circuit unit that performs drive control of the brake actuator 33 based on a control signal from the control unit 14 or detection signals from various sensors to perform vehicle braking control. As a result, the BK_ECU 23 generates braking forces for each wheel as appropriate to perform forced braking control, yaw rate control, etc. on the vehicle. The BK_ECU 23 also outputs signals of braking operation state, yaw rate, longitudinal acceleration, vehicle speed (host vehicle speed), etc. detected by various sensors to the control unit 14. Here, the BK_ECU 23, the brake actuator 33, and the above-mentioned various sensors (brake pedal sensor, etc.) form a braking control device.

[0042] In addition, various sensors 18, a wheel speed sensor 19, an inclination angle sensor 20, etc. are connected to the control unit 14. Here, the various sensors 18 include, for example, a locator unit, an in-vehicle radar device, a rear image sensor, a LiDAR (Light Detection And Ranging) device, a near-infrared sensor, an outside air temperature sensor, etc., although not shown.

[0043] 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 of the vehicle. The vehicle speed can be detected based on the wheel speed data of each wheel acquired by the wheel speed sensor 19.

[0044] The inclination angle sensor 20 is a gradient detection sensor that detects the gradient of the wheel contact surface on the road surface (ground) (hereinafter referred to as road surface gradient, etc.) by detecting the inclination of the vehicle in the longitudinal direction with respect to the horizontal.

[0045] The control unit 14 executes vehicle driving control based on the various information acquired by the camera unit 10, various sensors 18, wheel speed sensor 19, tilt angle sensor 20, etc. In this case, the driving control includes at least an output control of the drive motors (32F, 32R) by the D / M_ECU 22, torque distribution control of each drive wheel, etc., as well as individual braking control (brake control) of each wheel by the BK_ECU 23, and is vehicle driving control that is required as appropriate.

[0046] Furthermore, the control unit 14 includes therein a bad road area entry determination unit 15, a road surface μ estimation unit 16, a braking operation detection unit 17, and the like.

[0047] The rough road area entry determination unit 15 is a structural unit or circuit unit that determines whether or not the vehicle has entered a rough road area based on information acquired by the camera unit 10, various sensors 18, wheel speed sensor 19, and the like.

[0048] For example, the rough road area entry judgment unit 15 judges that the vehicle has entered a rough road area by detecting the degree of spinning or change in deceleration of the front or rear wheels from the detection value of the rotation angle of the drive motors 32F, 32R in response to the drive control signal output from the D / M_ECU 22 to the drive motors 32F, 32R, or the detection value of each wheel speed sensor 19 corresponding to the front or rear wheels.

[0049] In addition, the rough road area entry judgment unit 15 judges whether the vehicle is entering a rough road area by distinguishing between a paved road, an unpaved road, or an uneven ground, for example, based on the brightness difference of the wheel contact surface obtained from image data captured by the stereo camera 11.

[0050] In this case, when the road surface condition is recognized as being unpaved or rough, the type of the road surface may be further identified, for example, as muddy, sandy, or snowy.

[0051] Furthermore, the identification of whether the road is flooded (underpass, etc.) or whether the road is unpaved or rough and is an area where the vehicle is likely to get stuck may be performed taking into consideration the conditions of the route that has been traveled.

[0052] The road surface μ estimation unit 16 is a component unit 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, etc.

[0053] For example, the road surface μ estimation unit 16 estimates the road surface μ by detecting the degree of spinning of the front or rear wheels from the detection value of the rotation angle of the drive motors 32F, 32R in response to the drive control signal output from the D / M_ECU 22 to the drive motors 32F, 32R, or the detection value of each wheel speed sensor 19 corresponding to the front or rear wheels.

[0054] In this case, when estimating road surface μ, the road surface μ estimation unit 16 may further refer to information regarding the road surface conditions recognized by the image recognition unit 13 and detection values ​​of the near-infrared sensor, outside air temperature sensor, etc. included in the various sensors 18.

[0055] In addition, the road surface μ estimation unit 16 may distinguish between paved roads, unpaved roads, rough terrain, etc., based on the brightness difference of the wheel contact surface obtained from image data captured by the stereo camera 11, for example, and use this as an auxiliary criterion for estimating the road surface μ.

[0056] In this case, when the road surface condition is recognized as being unpaved or rough, detailed classification may be performed, for example, as muddy ground, sandy ground, or snowy ground, and this may be used as an auxiliary criterion for estimating road surface μ.

[0057] Furthermore, it is also possible to identify whether the road is a flooded road (underpass, etc.) or an area where the vehicle is likely to get stuck, such as an unpaved road or rough ground, and use this as an auxiliary criterion for estimating the road surface μ.

[0058] Furthermore, the road surface μ estimation unit 16 may use, for example, an auxiliary judgment criterion that the road surface μ is high when the outside air temperature is equal to or higher than a predetermined threshold, and may use, for example, an auxiliary judgment criterion that the road surface μ is low when the outside air temperature is less than the predetermined threshold.

[0059] The braking operation detection unit 17 is a configuration unit or a circuit unit that detects whether or not a braking operation is being performed by the driver by depressing the brake pedal, etc. The braking operation detection unit 17 detects the execution of a braking operation by receiving a predetermined output signal from the braking control device, i.e., an output signal from a brake pedal sensor transmitted through the BK_ECU 23.

[0060] In addition, all or part of the image recognition unit 13, control unit 14, bad road area entry judgment unit 15, road surface μ estimation unit 16, braking operation detection unit 17, CP_ECU 21, D / M_ECU 22, BK_ECU 23, etc. are configured by a processor including hardware.

[0061] Here, the processor is composed of a well-known configuration including, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a non-volatile memory, a non-volatile storage device, a non-transitory computer readable medium, and the like, and peripheral devices thereof.

[0062] Software programs executed by the CPU and fixed data such as data tables are stored in advance in ROM, non-volatile memory, non-volatile storage device, etc. Then, the CPU reads out the software programs stored in ROM, etc., expands them in RAM, and executes them, and the software programs appropriately refer to various data, etc., thereby realizing the functions of the above-mentioned components and components (13-17, 21-23), etc.

[0063] The processor may be configured with a semiconductor chip such as a Field Programmable Gate Array (FPGA), etc. Each of the above components and components (13 to 17, 21 to 23) may be configured with an electronic circuit.

[0064] Furthermore, the software program may be in a form in which the whole or part is recorded as a computer program product on a portable disk medium such as a flexible disk, CD-ROM, or DVD-ROM, or on a non-transitory computer readable medium such as a card-type memory, an HDD (Hard Disk Drive) device, or an SSD (Solid State Drive) device.

[0065] In general, for vehicles such as automobiles, an upper limit value of the depth at which the vehicle can be driven safely and reliably without being submerged even when the vehicle enters an area such as a puddle (hereinafter referred to as a limit depth value) is specified for each vehicle. This limit depth value is not only referred to when the vehicle enters an area such as a puddle, but also referred to as an upper limit value of the depth at which the driving force of the drive wheels can be reliably transmitted to the road surface when the vehicle enters an area such as a muddy area or an area with snow.

[0066] For example, if a vehicle enters an area such as a puddle and becomes submerged beyond a predetermined limit depth, there is a possibility that the vehicle will become unable to run due to events such as the vehicle's electrical system components becoming submerged.

[0067] In addition, for example, when a vehicle enters an area where it is easy to get stuck, such as mud or snow, and the vehicle exceeds a predetermined limit depth value and enters the area, such as mud or snow, the lower surface of the floor plate of the vehicle may come into contact with the ground (the top surface of the mud or snow, etc.). In this case, the wheels may not be able to ensure sufficient contact with the wheel contact surface, or even if the wheels are in contact with the ground, the road surface μ may be low, causing the drive wheels to spin, resulting in a so-called stuck state.

[0068] Here, the limit depth value in a vehicle will be explained below with reference to FIG. 2. FIG. 2 shows: FIG. 1 is a diagram for explaining the limit depth value of a vehicle traveling on a horizontal flooded road.

[0069] As limit depth values ​​stipulated for general vehicles, for example, the following rough standards are stipulated.

[0070] For example, Fig. 2 shows a situation in which a vehicle M is stationary or traveling on a horizontal road surface Ro. At this time, the road surface Ro is submerged as indicated by the symbol W. The symbol D indicates the depth of the submerged water W at this time.

[0071] 2, the water depth D of the flood water W is illustrated as having reached 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.

[0072] 2, the symbol M indicates a vehicle. The symbol WhF indicates a front wheel of the vehicle M, and the symbol WhR indicates a rear wheel of the vehicle M. The vehicle M is equipped with a camera unit 10. The camera unit 10 is fixed to a central portion of an upper portion near the front of the interior of the vehicle M.

[0073] 2, the symbol L1 indicates the flood surface of the flood water W. The symbol L2 indicates the lower surface side of the floor panel of the vehicle M. The symbol L3 indicates an imaginary straight line connecting the rotation center of the front wheels WhF and the rotation center of the rear wheels WhR of the vehicle M.

[0074] The limit depth value D1 defined for the vehicle M shown in FIG. 2 is desirably set, for example, to be equal to or less than the radius of the wheels (WhF, WhR) (L3≧D1), or to a level (L2≧D1) where the underside L2 of the floor plate of the vehicle M does not come into contact with the flooded surface L1 (or the muddy ground surface or the snow-covered surface, etc.).

[0075] In the situation shown in FIG. 2 (that is, when the vehicle M is on a horizontal road surface Ro), the camera unit 10 of the vehicle M can determine the water depth D of the submergence W based on the acquired image data.

[0076] For this purpose, first, the distance from the installation position of the camera unit 10 to the flood surface L1 (see symbol H1 in FIG. 2) is detected. Here, symbol H in FIG. 2 indicates the camera installation height of the camera unit 10. In other words, the camera installation height H is the distance to the point where a straight line extending vertically from the installation position of the camera unit 10 toward the road surface Ro intersects with the road surface Ro. This camera installation height H is a predetermined value defined for each vehicle.

[0077] Therefore, the water depth D in the situation shown in Figure 2 (when the vehicle M is horizontal) can be calculated from the distance H1 detected based on the image data of the camera unit 10 and the predetermined camera installation height H (D = H - H1).

[0078] Therefore, in the situation shown in Figure 2 (vehicle M is horizontal), by driving while detecting the water depth D using the camera unit 10, if the vehicle M is likely to exceed the limit depth value D1, braking control and driving force control can be performed appropriately to execute driving control to avoid submersion or getting stuck, etc.

[0079] The limit depth value D1 of the vehicle M refers to the length from the surface where the front wheels WhF of the vehicle M contact the road surface Ro to the submerged surface L1 on a straight line passing through the center of rotation of the front wheels WhF of the vehicle M, for example.

[0080] However, in a situation where vehicle M is traveling on a level road and enters an area where it is easy to get stuck, such as a puddle (see Figure 3), or in a situation where vehicle M is traveling on a sloping road and enters a flooded area (see Figure 4), the limit depth value D1 defined in the situation shown in Figure 2 (vehicle M is in a level situation) cannot be applied as is.

[0081] For example, consider a situation in which a vehicle M, while traveling on a horizontal road, enters a puddle W1 having a road surface gradient A, as shown in Fig. 3. In Fig. 3, symbol M indicates a vehicle traveling on a horizontal road surface Ro. Symbol D1 in Fig. 3 indicates the limit depth value of the vehicle M in this state (horizontal state). Arrow symbol F indicates the traveling direction of the vehicle M.

[0082] 3, the symbol M1 indicates a part of the vehicle M when the front wheels WhF enter the puddle W1 after the vehicle M travels along the traveling direction F. Here, only the front half of the vehicle M1 is shown, and the rear half is not shown. The symbol Ro indicates the horizontal road surface, and the symbol Ro1 indicates the road surface at the puddle W1 portion having a road surface gradient A.

[0083] In this case, the front wheels WhF of the vehicle M1 have entered the water up to a depth of D2, as shown in Fig. 3. The water depth D2 at this time is smaller than the limit depth value D1 when the vehicle is horizontal (D1>D2). However, at this point (the position of the vehicle M1), the front end portion (see symbol B) of the vehicle M1 is already close to being submerged. Therefore, the water depth D2 at this point can be said to be the limit depth value for the vehicle M1 under these circumstances.

[0084] In this way, the limit depth value (D2) of the vehicle M1 when entering the puddle W1 having the road surface gradient A is smaller than the limit depth value D1 of the vehicle M in a horizontal state (D1>D2).

[0085] Also, for example, consider a situation in which a vehicle M travels on a road having a road surface gradient A1 and enters a flooded portion W2, as shown in Fig. 4. In Fig. 4, symbol M indicates a vehicle traveling on a road surface Ro2 having a road surface gradient A1. Symbol D1 indicates a limit depth value when vehicle M is in a horizontal state. Symbol W2 indicates a flooded portion. Here, the situation shown in Fig. 4 assumes a situation in which vehicle M enters a flooded portion W2, such as an underpass, on a paved road (road surface Ro2).

[0086] In this case, the front wheels WhF of the vehicle M have penetrated to a water depth of D3 as shown in Fig. 4. The water depth D3 at this time is smaller than the limit depth value D1 when the vehicle is horizontal (D1>D3). However, at this point in time (when the front wheels WhF have penetrated to the water depth D3), the frontmost portion B of the vehicle M is already close to being submerged. Therefore, the water depth D3 at this point in time can be said to be the limit depth value for the vehicle M under these circumstances.

[0087] In this way, the limit depth value D3 of the vehicle M when traveling on a road surface Ro2 having a road surface gradient A1 and entering the flooded area W2 is smaller than the limit depth value D1 of the vehicle M in a horizontal state (D1>D3).

[0088] In this way, the limit depth value in a situation where the vehicle M is entering an area where it is easy to get stuck, such as a puddle (see FIG. 3), or in a situation where the vehicle M is entering a flooded area from a sloping road (see FIG. 4), requires a predetermined correction to be made to the limit depth value in a situation where the vehicle M is traveling in a horizontal state (see FIG. 2). The predetermined correction to the limit depth value in this case can be determined in advance according to the vehicle's traveling conditions and the road surface gradient.

[0089] And the vehicle's driving conditions, e.g. (1) Driving on a level road surface (Figure 2) (2) When entering an area with a slope from a horizontal road where it is easy to get stuck (the situation in Figure 3) (3) Situation when driving on a sloped road and entering a flooded area (situation in Figure 4) It would be convenient to prepare a correction map for the limit depth value according to the above. In this case, a correction value according to the road surface gradient for each situation may be specified.

[0090] Next, among the operations of the cruise control device 1 according to one embodiment of the present invention, cruise control when the vehicle M is traveling in a rough road area will be described below with reference to Fig. 5. Fig. 5 is a flowchart showing part of the operation of the cruise control device for a vehicle according to one embodiment of the present invention, that is, cruise control when traveling in a rough road area.

[0091] First, the vehicle M equipped with the cruise control device 1 of this embodiment is traveling forward on a road or the like. Here, the term "road" includes not only general public roads and private roads, but also areas other than general roads, such as public or private land such as campsites or riverbeds. When the vehicle M is traveling, the cruise control device 1 of this embodiment mounted on the vehicle M is in an activated state.

[0092] 5, the control unit 14 executes a surrounding environment recognition process to recognize the surrounding environment 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 tilt angle sensor 20, etc. This surrounding environment recognition process is continuously executed while the cruise control device 1 of the vehicle M is in an activated state.

[0093] In step S2, the bad road area entry determination section 15 of the control unit 14 determines whether or not the vehicle M has entered a bad road area, based on the information acquired in the process of step S1 described above.

[0094] Here, a bad road area refers to an area with road conditions such as an unpaved road or an uneven ground other than a paved road, where there are areas where it is easy to get stuck.

[0095] The determination of whether the vehicle M has entered a rough road area is made, for example, by detecting a brightness difference or the like of the wheel contact surfaces around the vehicle M based on image data captured by the stereo camera 11 of the camera unit 10, and making a determination based on the detection result. Also, for example, based on wheel speed data of each wheel (four wheels) of the vehicle M acquired by the wheel speed sensor 19, a change in each wheel speed or the like is detected, and a determination of whether the vehicle M has entered a rough road area is made based on the detection result.

[0096] If it is determined in step S2 that the vehicle has entered a bad road area, the process proceeds to step S3, or if it is not determined that the vehicle has entered a bad road area, the process returns to step S1 and repeats the subsequent steps.

[0097] In step S3, the control unit 14 receives output data from the inclination angle sensor 20 and detects the road surface inclination.

[0098] Next, in step S4, the control unit 14 causes the road surface μ estimating section 16 to estimate the road surface μ of the wheel contact surface around the vehicle M based on output data from the camera unit 10, various sensors 18, wheel speed sensor 19 and the like.

[0099] 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) and checks whether the road surface gradient is greater than a predetermined threshold value and the estimated road surface μ is lower than a predetermined threshold value. If the road surface gradient is large and the estimated road surface μ is low, the process proceeds to the next step S6. If the case is other than "road surface gradient is large" and "estimated road surface μ is low", the process proceeds to step S7.

[0100] In step S6, the bad road area entry determination section 15 of the control unit 14 checks whether all the wheels are likely to enter an area where they are likely to get stuck, or whether the limit depth value is likely to be reached, based on the output data from the camera unit 10, various sensors 18, wheel speed sensor 19, etc. If all the wheels are likely to enter, or the limit depth value is likely to be reached, the process proceeds to step S8. If neither of these conditions is met, the process returns to step S1, and the subsequent processes are repeated.

[0101] Meanwhile, in step S7, the bad road area entry determination section 15 of the control unit 14 checks whether or not the limit depth value is about to be reached based on output data from the camera unit 10, various sensors 18, wheel speed sensor 19, etc. If the limit depth value is about to be reached, the process proceeds to step S8. If the limit depth value is not about to be reached, the process returns to step S1 and the subsequent processes are repeated.

[0102] In step S8, the control unit 14 executes a first notification process using the notification device 31a. The notification content in this first notification process is, for example, a warning notification such as "Further forward movement may result in getting stuck."

[0103] Next, in step S9, the control unit 14 detects whether or not the driver is performing a braking operation in the braking operation detection section 17. Here, the braking operation by the driver can be detected by detecting an output signal of a brake pedal sensor (not shown).

[0104] In the process of step S9, if a braking operation by the driver is not detected, the process proceeds to step S10, whereas, if a braking operation by the driver is detected, the process proceeds to step S12.

[0105] In step S10, the control unit 14 executes a predetermined automatic deceleration control process by controlling the brake actuator 33 via the BK_ECU 23. This automatic deceleration control is a braking control by the braking control device (such as the BK_ECU 23), and is a first avoidance control that prevents the vehicle M from entering an area in a bad road area where the vehicle M is likely to get stuck.

[0106] Next, in step S11, the control unit 14 executes a second notification process using the notification device 31a. The notification content in this second notification process is, for example, a warning notification such as "After automatic stopping, the vehicle will reverse. Do not put your foot on the brake pedal." Then, the process proceeds to step S20.

[0107] On the other hand, when the braking operation by the driver is detected in the process of step S9 described above and the process proceeds to step S12, the control unit 14 executes a third notification process using the notification device 31a in this step S12. The notification content in this third notification process is, for example, a warning notification such as "Reversing. Please take your foot off the brake pedal." Then, the process proceeds to step S20.

[0108] In step S20, the control unit 14 executes a predetermined escape driving control process. This escape driving control is a drive control by the driving force control device (D / M_ECU 22, etc.), and is a second avoidance control that prevents the vehicle M from entering an area in a bad road area where the vehicle M is likely to get stuck, and escapes from the area.

[0109] FIG. 6 shows a subroutine for the escape drive control process.

[0110] In step S21 of Fig. 6, the bad road area entry determination section 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) and checks whether the road surface gradient is greater than a predetermined threshold value and the estimated road surface μ is lower than a predetermined threshold value. If the road surface gradient is large and the estimated road surface μ is low, the process proceeds to the next step S22. If the case is other than "road surface gradient is large" and "estimated road surface μ is low", the process proceeds to step S23.

[0111] In step S22, the control unit 14 controls the drive motors 32F, 32R via the D / M_ECU 22 to perform reverse driving control using drive distribution control that primarily drives the rear wheels and suppresses drive of the front wheels.

[0112] As described above, the situation at this time is one in which the road gradient is large and the estimated road μ is low. Also, at this time, the front wheels have entered an area where it is easy to get stuck, but the rear wheels have not yet entered an area where it is easy to get stuck. Therefore, in this situation, it is considered that it is easy to escape from the situation by performing drive distribution control that mainly applies drive force to the rear wheels. Therefore, in the processing of step S22, drive control is performed that mainly drives the rear wheels and suppresses the transmission of drive force to the front wheels. At this time, reverse driving control is used to get the vehicle M out of the situation. Thereafter, the original processing is returned to.

[0113] In step S23, the control unit 14 controls the drive motors 32F, 32R via the D / M_ECU 22 to drive all the wheels and execute reverse drive control, and then returns to the original process (RETURN).

[0114] As described above, according to the embodiment, when it is detected that the vehicle M is traveling on a rough road area and is about to enter an area where the vehicle M is likely to get stuck, such as a puddle, mud, or snow, the vehicle M is decelerated or stopped before the vehicle M reaches the limit depth value. In this case, first, the notification device 31a issues a first notification to the driver to prompt the driver to apply the brakes, or automatic braking control is performed to prevent the vehicle M from entering the area where the vehicle M is likely to get stuck (first avoidance control).

[0115] In this case, the timing for preventing entry into the region where the vehicle is likely to get stuck is varied 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 executed before all the wheels enter the region where the vehicle is likely to get stuck. In other cases, the first avoidance control is executed before the limit depth value is reached. This control is designed to take into consideration that the larger the road surface gradient is and the lower the estimated road surface μ is, the more difficult it becomes to escape from the region where the vehicle is likely to get stuck. In other words, the escape control is executed at a stage before all the wheels enter the region where the vehicle is likely to get stuck.

[0116] In this way, the vehicle M is stopped by deceleration control before it gets stuck in the area where it is likely to get stuck, and then reverse driving control is performed to escape from the area where it is likely to get stuck. In this case, by appropriately changing the distribution of driving force between the rear wheels and the front wheels during reverse driving according to the road surface gradient and the estimated road surface μ, it is possible to smoothly and reliably escape from the area.

[0117] Specifically, when the road gradient is large and the estimated road μ is low, reverse drive control is performed using drive distribution control that mainly drives the rear wheels and suppresses the drive of the front wheels, and in other cases, reverse drive control is performed that drives all the wheels.

[0118] By executing such driving control, it is possible to prevent the vehicle M from becoming submerged or stuck in water.

[0119] The present invention is not limited to the above-mentioned embodiment, and various modifications and applications can be implemented within the scope of the gist of the invention. Furthermore, the above-mentioned embodiment includes inventions at various stages, and various inventions can be extracted by appropriate combinations of the disclosed multiple constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the above-mentioned one embodiment, if the problem to be solved by the invention can be solved and the effect of the invention can be obtained, the configuration from which the constituent elements are deleted can be extracted as the invention. Furthermore, the constituent elements across different embodiments may be appropriately combined. The present invention is not restricted by its specific embodiment except as limited by the appended claims. [Explanation of symbols]

[0120] 1...Drive control device 10...Camera unit 11...Stereo camera 11a…Main camera 11b…Sub camera 12...Image processing unit (IPU) 13...Image recognition unit 14…Control unit (M_ECU) 15...Rough road area entry determination section 16…Road surface μ estimation unit 17...Braking operation detector 18...Various sensors 18 19...Wheel speed sensor 20...Tilt angle sensor 21…CP_ECU 22…D / M_ECU 23…BK_ECU 31…Human Machine Interface (HMI) 31a…Alarm device 32F…Front drive motor 32R…Rear drive motor 33...Brake actuator A, A1…Road gradient B: Front end of the vehicle D, D2, D3…Water depth D1: Depth limit F…Direction of travel H: Camera installation height H1: Distance from the camera position to the flooded surface L1…Flooded surface L2: Underside of floorboard L3: Imaginary line connecting the center of rotation of the front wheels and the center of rotation of the rear wheels M, M1…Vehicle Ro…road surface Ro1: Road surface with puddle slope Ro2: Gradient road surface W…Flooded W2: Flooded area WhF…Front wheel WhR…Rear wheel

Claims

1. A surrounding environment recognition device that acquires surrounding environment information for a vehicle; A braking control device that performs braking control of the vehicle; A driving force control device that controls the driving of the front wheels and the rear wheels separately; A control unit including at least a rough road area entry determination unit that determines whether the vehicle has entered a rough road area, and a road surface μ estimation unit that estimates a friction coefficient of a wheel contact surface; Equipped with When the control unit determines that the vehicle is likely to enter an area in a bad road area where the vehicle is likely to get stuck based on a result of the determination by the bad road area entry determination unit, the control unit executes a first avoidance control and then executes a second avoidance control. A vehicle driving control device comprising:

2. The first avoidance control is a braking control by the braking control device, The second avoidance control is a drive control by the drive force control device.

2. The vehicle travel control device according to claim 1.

3. An alarm device, The control unit further includes a braking operation detection unit that detects a braking operation by a driver, The control unit Based on a result of the determination by the bad road area entry determination unit, it is determined that the vehicle is likely to enter an area in a bad road area where the vehicle is likely to get stuck; and When a braking operation by the driver is detected based on the detection result by the braking operation detection unit, After issuing a warning by the notification device, the second avoidance control is executed.

2. The vehicle travel control device according to claim 1.

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