Vehicle control device and vehicle control method

Abstract

The objective is to provide a vehicle control device and a vehicle control method that can estimate the degree to which the vehicle's tires are sinking into the road surface based on images captured by a camera, when the vehicle is traveling in an area where it is difficult to recognize feature points from images of the road surface in the direction of travel. [Solution] The present invention acquires images from a rear camera that photographs the road surface in the direction opposite to the direction of travel of the vehicle, calculates a first distance between the vehicle body and the road surface based on the images, using the ruts created on the road surface by the vehicle's movement as feature points, and estimates the amount of sinking of the tires into the road surface based on the first distance and a second distance between the vehicle body and the contact point of the vehicle's tires.

Description

Technical Field

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[0001] The present invention relates to a vehicle control device and a vehicle control method.

Background Art

[0002] Based on a captured image obtained by capturing the traveling direction of a vehicle with a capturing unit, a convex portion on the traveling path in the traveling direction of the vehicle is detected, and the driving force and braking force of the vehicle are controlled based on the structural characteristics including the height of the convex portion and the current vehicle speed (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1, when the vehicle travels in a place where it is difficult to recognize feature points from an image of the road surface in the traveling direction, such as sandy ground, the distance between the vehicle body and the road surface cannot be measured from the image, and there is a problem that the degree to which the vehicle tires sink into the road surface cannot be estimated.

[0005] The problem to be solved by the present invention is to provide a vehicle control device and a vehicle control method that can estimate the degree to which the vehicle tires sink into the road surface based on a captured image of a camera when the vehicle travels in a place where it is difficult to recognize feature points from an image of the road surface in the traveling direction.

Means for Solving the Problems

[0006] The present invention solves the above problem by acquiring images from a rear camera that photographs the road surface in the direction opposite to the direction of travel of the vehicle, calculating a first distance between the vehicle body and the road surface based on the captured images, using the ruts created on the road surface by the vehicle's movement as feature points, and estimating the amount of sinking of the tires into the road surface based on the first distance and a second distance between the vehicle body and the contact point of the vehicle's tires. [Effects of the Invention]

[0007] According to the present invention, when a vehicle is traveling through an area where it is difficult to recognize feature points from images of the road surface in the direction of travel, the degree to which the vehicle's tires are sinking into the road surface can be estimated based on the images captured by the camera. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows the configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] Figure 2 is a diagram illustrating the camera and distance calculation range according to this embodiment. [Figure 3] Figure 3 shows an example of each distance calculated in this embodiment. [Figure 4] Figure 4 shows an example of the relationship between settlement amount and risk in this embodiment. [Figure 5] Figure 5 shows an example of the relationship between settlement amount and risk in this embodiment. [Figure 6] Figure 6 shows an example of a risk notification method in this embodiment. [Figure 7] Figure 7 is a flowchart showing the control process flow of the vehicle control method according to this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a diagram showing the configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. As shown in Figure 1, the vehicle 1 has a vehicle control device 10, a camera 11, a vehicle information acquisition device 12, an input device 13, an output device 14, and a drive control device 15. These devices are mounted on the vehicle and are connected by CAN or other in-vehicle LAN to exchange information with each other. The vehicle control device 10 is a device that controls the vehicle 1. The vehicle control device 10 acquires various information from the camera 11 and the vehicle information acquisition device 12, and based on the acquired information, determines the control necessary for the vehicle 1 to run and controls the running of the vehicle 1.

[0010] Camera 11 is a camera mounted on the vehicle 1 that detects the driving environment around the vehicle 1. Camera 11 acquires captured images of objects around the vehicle 1. Camera 11 is, for example, a camera equipped with an image sensor such as a CCD, and is a stereo camera. For example, camera 11 photographs the road surface on which the vehicle 1 is traveling. The detection results from camera 11 are output to the vehicle control device 10.

[0011] Camera 11 includes a rear camera that photographs the road surface in the direction opposite to the direction of travel of the vehicle 1. For example, the rear camera is installed at the rear of the vehicle 1. In this embodiment, when the vehicle 1 is traveling in an area where it is difficult to recognize characteristic points of the road surface in the direction of travel of the vehicle 1, such as sand or snow, camera 11 photographs the road surface in the direction opposite to the direction of travel of the vehicle 1. Multiple cameras 11 can be installed on a single vehicle. Camera 11 may also include a front camera that photographs the road surface in the direction of travel of the vehicle 1. For example, the front camera is installed at the front of the vehicle 1.

[0012] The vehicle information acquisition device 12 acquires vehicle information relating to the state of the vehicle 1. The vehicle information acquisition device 12 acquires vehicle information from various on-board sensors that detect various types of information. The vehicle information includes the speed of the vehicle 1 (the speed of the vehicle body and the wheel speed of the vehicle 1), the longitudinal acceleration of the vehicle 1, and the steering angle of the vehicle 1.

[0013] The input device 13 is, for example, a dial switch that can be operated manually by the driver, a touch panel located on a display screen, or a microphone that can be used for input by the driver's voice. The information input to the input device 13 is output to the vehicle control device 10. The information input to the input device 13 is, for example, selection information indicating whether or not to set the driving mode of the vehicle 1 to the stuck avoidance mode. The stuck avoidance mode is a mode in which avoidance control is performed to prevent the vehicle 1 from getting stuck when there is a risk of the vehicle 1 getting stuck on the road surface. Details will be described later.

[0014] The output device 14 is, for example, a display on the vehicle 1. The output device 14 is a device such as a navigation display, a display built into a mirror, a display built into the meter section, a head-up display projected onto the windshield, or a speaker provided by an audio system. The output device 14 outputs information indicating the amount of subsidence and / or risk, as described later, to the occupants of the vehicle 1. The occupants of the vehicle 1 are, for example, the driver of the vehicle 1. As an example of the output method, an image representing the amount of subsidence and / or risk is displayed on the display of the output device 14. Note that the input device 13 and the output device 14 may be configured as an integrated device, such as a touch panel display.

[0015] The drive control device 15 controls the movement of the vehicle 1. The drive control device 15 includes a brake control mechanism, an accelerator control mechanism, an engine control mechanism, and HMI (human interface) equipment, etc. Control signals are input to the drive control device 15 from the vehicle control device 10. In response to the control from the vehicle control device 10, the drive control device 15 performs autonomous driving of the vehicle 1 by controlling the operation of the drive mechanism (including the operation of the internal combustion engine in the case of an engine-powered vehicle, the operation of the electric motor in the case of an electric vehicle, and the torque distribution between the internal combustion engine and the electric motor in the case of a hybrid vehicle), brake operation, and steering actuator operation, etc. The drive control device 15 may also control the direction of movement of the vehicle 1 by controlling the control amount of each wheel of the vehicle in response to the control signals from the vehicle control device 10. The control of each mechanism may be performed completely automatically, or it may be performed in a manner that assists the driver's operation.

[0016] The vehicle control device 10 consists of a ROM that stores a program for controlling the vehicle 1, a CPU that executes the program stored in the ROM, and RAM that functions as an accessible storage device. The vehicle control device 10 realizes various functions for controlling the vehicle 1 by executing the program stored in the ROM using the CPU. Specifically, the vehicle control device 10 recognizes the driving environment around the vehicle 1 based on the vehicle information of the vehicle 1 and surrounding information, and controls the driving of the vehicle 1 in accordance with the surrounding driving environment. For example, the vehicle control device 10 calculates a control amount for controlling the driving of the vehicle 1 and outputs a control signal corresponding to the control amount to the drive control device 15. The vehicle control device 10 also controls the on-board equipment, including the output device 14, by outputting control signals to the on-board equipment.

[0017] In this embodiment, the vehicle control device 10 estimates the amount of sinking of the vehicle's tires as it travels along the road surface. In particular, the vehicle control device 10 estimates the amount of sinking when the vehicle travels through a specific area. A specific area is one in which it is difficult to recognize characteristic points of the road surface from images taken of the road surface in the direction of travel of the vehicle. Examples of specific areas include sandy areas and snowy areas. In specific areas, it is difficult to recognize the road surface based on its characteristic points, making it difficult to accurately calculate the distance between the vehicle body and the road surface, which can lead to large errors. The vehicle control device 10 also calculates the risk of the vehicle getting stuck on the road surface based on the estimated amount of sinking. The vehicle getting stuck means that the tires of the vehicle get stuck in the road surface, preventing the vehicle from moving forward. When vehicle 1 travels on sandy ground, the amount of tire sinking of vehicle 1 can be used to determine the driving resistance that vehicle 1 experiences from the sand, thereby allowing for the calculation of the risk of vehicle getting stuck. The vehicle control device 10 comprises, as functional blocks, an image acquisition unit 101, a distance calculation unit 102, a sinking amount estimation unit 103, a risk calculation unit 104, and a vehicle control unit 105. The vehicle control device 10 realizes each of the above functions by executing a program stored in ROM using a CPU.

[0018] The image acquisition unit 101 acquires a captured image including the driving environment around the host vehicle 1 from the camera 11. The captured image is an image acquired from the rear camera and includes the driving road surface in the direction opposite to the traveling direction of the host vehicle 1. While the host vehicle 1 is traveling, a rut is formed on the driving road surface in the direction opposite to the traveling direction of the host vehicle 1 due to the travel of the host vehicle 1. That is, the driving road surface is divided into a rut portion and a portion where no rut exists (also referred to as a flat portion). Therefore, the acquired captured image includes the rut on the driving road surface. The image acquisition unit 101 performs image recognition processing on the acquired captured image and extracts the rut included in the captured image as a feature point. Further, the rut is composed of an inclined surface and a bottom surface. The inclined surface is a side surface portion of the rut and is inclined from the upper side to the lower side. The bottom surface is a substantially horizontal surface located below the inclined surface between the left and right inclined surfaces. The image acquisition unit 101 may extract the boundary portion of the rut (the boundary portion between the inclined surface of the rut and the flat portion) as a feature point, or may extract the inclined surface or the bottom surface as a feature point.

[0019] Here, the camera and the distance calculation region according to the present embodiment will be described with reference to FIG. 2. FIG. 2 is a diagram for explaining the camera and the distance calculation region according to the present embodiment. In (A) of FIG. 2, the surrounding environment including the driving road surface behind the host vehicle 1 is shown. In the example of FIG. 2, the camera 11 is mounted on the rear portion of the host vehicle 1. The camera 11 is, for example, a stereo camera. The camera 11 captures the surrounding environment including the driving road surface. The region A on the driving road surface is a distance calculation region in which the distance between the camera 11 and the vehicle body of the host vehicle 1 is calculated. (B) of FIG. 2 is an example of a display screen on which the shape of the driving road surface in the direction opposite to the traveling direction of the host vehicle 1 is drawn three-dimensionally. In (B) of FIG. 2, based on the distances at each position within the distance calculation region A shown in (A) of FIG. 2, the shape of the driving road surface in the distance calculation region A is drawn three-dimensionally. (C) of FIG. 2 shows an example of the driving road surface in the direction opposite to the traveling direction of the host vehicle 1. After the host vehicle 1 has traveled, a rut C has occurred on the driving road surface B in the direction opposite to the traveling direction of the host vehicle 1. As a result, the driving road surface B has a rut C and a flat portion D.

[0020] The distance calculation unit 102 calculates a first distance between the vehicle body of the host vehicle 1 and the driving road surface, using the rut portion extracted by the image acquisition unit 101 as a feature point. More specifically, the first distance is the distance between the position of the camera 11 mounted on the vehicle body of the host vehicle 1 and the flat portion of the driving road surface. For example, the distance calculation unit 102 calculates, as the first distance, the distance between the vehicle body of the host vehicle 1 and the position of the feature point by using the boundary portion of the rut portion as the feature point of the driving road surface. Since the boundary portion of the rut portion is the boundary with the flat portion and is considered to be at the same height as the flat portion, the boundary portion of the rut portion is used as the feature point of the driving road surface for calculating the first distance. When the camera 11 is a stereo camera, the first distance is calculated from the disparity image including the feature point of the driving road surface. Note that the first distance is not limited to the distance between the position of the camera 11 mounted on the vehicle body of the host vehicle 1 and the driving road surface, as long as it is a distance based on the vehicle body of the host vehicle 1. For example, it may be the distance between the bottom surface portion of the vehicle body of the host vehicle 1 and the driving road surface. Further, the distance calculation unit 102 may calculate the distance between the vehicle body of the host vehicle 1 and the inclined surface or the bottom surface of the rut portion of the driving road surface. For example, as shown in the example of FIG. 2, the distance between each position within the distance calculation area A on the driving road surface and the vehicle body of the host vehicle 1 may be calculated.

[0021] Here, an example of each distance calculated in the present embodiment will be described with reference to FIG. 3. FIG. 3 is a diagram showing an example of each distance calculated in the present embodiment. As shown in FIG. 3, the distance calculation unit 102 calculates a first distance D1 between the camera 11 and the driving road surface (flat portion) B. Further, the distance calculation unit 102 preliminarily acquires a second distance between the vehicle body of the host vehicle 1 and the ground contact point of the tire of the host vehicle 1. The second distance is, for example, the distance between the position of the camera 11 mounted on the vehicle body of the host vehicle 1 and the position of the ground contact point of the tire of the host vehicle 1. For example, the second distance may be a distance predetermined by the design of the vehicle. The second distance may be a distance taking into account the stroke amount of the suspension of the host vehicle 1. Further, the second distance may be the distance between the vehicle body of the host vehicle 1 and the driving road surface acquired in advance during normal on-road driving. Further, the second distance may be calculated with the position of the bottom surface C of the rut portion as the ground contact point of the tire.

[0022] The settlement estimation unit 103 estimates the amount of settlement in which the tires of the vehicle 1 sink into the road surface, based on the first distance and the second distance. As shown in the example in Figure 3, the settlement amount S is estimated as the value obtained by subtracting the first distance from the second distance.

[0023] Furthermore, the settlement estimation unit 103 may store the settlement amount estimated while the vehicle 1 is traveling on the road surface as an estimation history. For example, when the vehicle 1 starts traveling in a specific area such as sandy ground, the settlement estimation unit 103 estimates the settlement amount at regular intervals. The settlement estimation unit 103 stores multiple estimated settlement amounts in chronological order. The stored estimation history includes chronological data of settlement amounts from a predetermined point in the past to the present. The predetermined point in the past is, for example, the point in time when the vehicle 1 started traveling in a specific area.

[0024] The risk calculation unit 104 calculates the risk of the vehicle 1 getting stuck on the road surface based on the amount of settlement. This risk is also called the stuck risk. The risk is expressed as a numerical value indicating the possibility of getting stuck. For example, the risk is a value between 0 and 1. The larger the number, the higher the risk of the vehicle 1 getting stuck. For example, the risk calculation unit 104 calculates a higher risk the greater the amount of settlement. This is because when a vehicle is driving on sand, the more the tires are buried in the road surface, the greater the resistance from the sand, and the higher the risk of the vehicle 1 getting stuck. Also, when the tires are buried in the road surface, the body of the vehicle 1 comes into contact with the road surface, further increasing the resistance. Here, an example of the relationship between the amount of settlement and the risk in this embodiment will be explained using Figure 4. Figure 4 is a diagram showing an example of the relationship between the amount of settlement and the risk in this embodiment. The vertical axis represents the risk, and the horizontal axis represents the amount of settlement. As shown in Figure 4, when the amount of settlement is less than or equal to a predetermined first settlement amount S1, the risk is 0. When the amount of settlement exceeds a predetermined first settlement amount S1, the risk increases in proportion to the increase in settlement. The risk reaches its maximum value (=1) when the amount of settlement exceeds a predetermined second settlement amount (for example, the height of the bottom surface of the vehicle body).

[0025] Furthermore, the risk calculation unit 104 may calculate the risk based on at least one of the following factors in addition to the amount of sinking: the speed of the vehicle 1, the slip ratio of the vehicle 1's tires, the steering angle of the vehicle 1, the gradient of the road surface, and the amount of moisture on the road surface. The risk calculation unit 104 acquires vehicle information from the vehicle information acquisition device 12 and calculates the risk based on the acquired information. For example, the risk calculation unit 104 calculates a lower risk the higher the speed of the vehicle 1. The higher the speed of the vehicle 1, the more the vehicle body moves due to inertia, thus reducing the risk of the vehicle 1 getting stuck. The risk calculation unit 104 calculates a higher risk the greater the slip ratio of the vehicle 1's tires. When the vehicle 1 is driving on sandy ground, if the slip ratio is high, the tires will sink further into the sand as they dig, increasing resistance from the sand and increasing the risk of the vehicle 1 getting stuck. The slip ratio is calculated from the speed and wheel speed of the vehicle 1. The risk calculation unit 104 calculates a higher risk the larger the steering angle of the vehicle 1. When the steering angle is large, the rolling resistance that the tires experience from the sand increases, increasing the risk of the vehicle getting stuck. The risk calculation unit 104 also calculates a higher risk the greater the gradient of the road surface. The gradient of the road surface is calculated from the longitudinal acceleration of the vehicle 1. In addition, the risk calculation unit 104 calculates a lower risk the greater the moisture content of the road surface. The moisture content of the road surface is estimated from images taken of the road surface. For example, the condition of the road surface and the moisture content are pre-associated using machine learning or the like.

[0026] Here, an example of the risk calculation method according to this embodiment will be explained using Figure 5. Figure 5 is a diagram showing an example of the relationship between settlement and risk in this embodiment. Similar to the example in Figure 4, the risk is calculated such that the greater the settlement, the higher the risk. In the example in Figure 5, the relationship between settlement and risk changes depending on the speed of the vehicle 1. Each graph shown in Figure 5 shows a different relationship between settlement and risk for each speed of the vehicle 1. The higher the speed of the vehicle 1, the smaller the risk for settlement. That is, even if the settlement is the same value, the higher the speed of the vehicle 1, the smaller the risk. When the speed of the vehicle 1 is 0 kph, the risk for settlement is the largest (see graph G in Figure 5). The risk calculation unit 104 calculates the risk corresponding to the settlement and the speed of the vehicle 1 based on the settlement and the speed of the vehicle 1.

[0027] Furthermore, the risk calculation unit 104 may calculate the risk by multiplying the risk calculated based on the amount of settlement by a predetermined gain. The predetermined gain includes gains corresponding to the slip ratio of the vehicle 1, the tire angle of the vehicle 1, the gradient of the road surface, and the moisture content of the road surface. Note that all of these gains may be multiplied by the risk, or any one of these gains may be multiplied by the risk. First, the risk calculation unit 104 calculates each gain based on the slip ratio of the vehicle 1, the tire angle of the vehicle 1, the gradient of the road surface, and the moisture content of the road surface. For example, the gain corresponding to the slip ratio is expressed as a value between 1 and 2. The larger the slip ratio, the larger the value of the gain corresponding to the slip ratio. The gain corresponding to the tire angle, the gain corresponding to the gradient of the road surface, and the gain corresponding to the moisture content of the road surface are expressed as values ​​between 0 and 1. The larger the tire angle, the smaller the value of the gain corresponding to the tire angle. The larger the gradient of the road surface, the smaller the value of the gain corresponding to the gradient of the road surface. The larger the moisture content of the road surface, the smaller the value of the gain corresponding to the moisture content of the road surface. The risk calculation unit 104 calculates the risk by multiplying each calculated gain by the risk calculated based on the amount of settlement. Note that the risk to which the gain is multiplied is not limited to the risk calculated based on the amount of settlement, but may also be the risk calculated based on the amount of settlement and the speed of the vehicle 1.

[0028] The risk calculation unit 104 may also calculate the risk based on the estimated history. The risk calculation unit 104 refers to time-series data of the amount of settlement and estimates the change in the amount of settlement from a predetermined point in the past to the present. When the risk calculation unit 104 estimates that the amount of settlement is decreasing, it calculates the risk so that it is lower than when the amount of settlement has not changed or when the amount of settlement is estimated to be increasing. For example, the risk calculation unit 104 calculates the risk by multiplying the risk calculated based on the current amount of settlement by a gain corresponding to the change in the amount of settlement. The gain when the amount of settlement is estimated to be decreasing is smaller than the gain when the amount of settlement has not changed or when the amount of settlement is estimated to be increasing. For example, the gain corresponding to the change in the amount of settlement is set to a value less than 1 when the amount of settlement is estimated to be decreasing. Also, the gain corresponding to the change in the amount of settlement is set to a value greater than 1 when the amount of settlement is estimated to be increasing.

[0029] The vehicle control unit 105 controls the on-board equipment, including the output device 14 and the drive control device 15. For example, the vehicle control unit 105 controls the output device 14 to inform the occupants of the vehicle 1 of the amount of sinking and / or the risk. Examples of notification methods include displaying an image showing the value of the amount of sinking and / or the risk, and issuing a warning according to the value of the amount of sinking and / or the risk. By understanding the situation of the vehicle 1's tires sinking and the risk of the vehicle 1 getting stuck, the driver can take action to avoid the vehicle 1 getting stuck. In addition, an image visually representing the amount of sinking and / or the risk, as shown in Figures 2 and 6, may be displayed on the output device 14. Figure 6 is a diagram showing an example of a risk notification method in this embodiment. In the example in Figure 6, a wireframe representing the magnitude of the risk in color is displayed on the display of the output device 14. For example, the position of the wireframe corresponding to the high-risk part of the vehicle body is displayed in red.

[0030] The vehicle control unit 105 controls the drive torque of the vehicle 1 to reduce the risk according to the risk. Generally, when the vehicle 1 slips, the amount of sinking increases, and the driving resistance increases. Therefore, it is necessary to drive the vehicle 1 in a way that suppresses slipping. For example, the vehicle control unit 105 calculates an upper limit of the slip ratio according to the risk. The upper limit of the slip ratio is calculated to be smaller as the risk increases. The vehicle control unit 105 controls the wheel speed of the vehicle 1 so as not to exceed the upper limit of the slip ratio. For example, the vehicle control unit 105 sets an upper limit of the wheel rotation speed so as not to exceed the upper limit of the slip ratio, and controls the drive torque based on that upper limit of the wheel rotation speed. In this embodiment, the vehicle control unit 105 may also perform drive torque control according to the risk when the vehicle 1 occupant has set the stuck avoidance mode. The vehicle 1 occupant can input via the input device 13 whether or not to set the driving mode of the vehicle 1 to the stuck avoidance mode.

[0031] An example of the control process of the vehicle control method according to this embodiment will be explained using Figure 7. Figure 7 is a flowchart of the control process of the vehicle control method according to this embodiment. In this embodiment, when the vehicle 1 starts driving in a predetermined area such as sand, the controller 100 starts the control flow of step S1. While the vehicle 1 is driving in the predetermined area, the controller 100 repeatedly executes the control flow shown in Figure 7 at regular intervals.

[0032] In step S1, the controller 100 acquires an image from the camera 11 of the road surface in the opposite direction to the direction of travel of the vehicle 1. In step S2, the controller 100 calculates a first distance between the vehicle body and the road surface based on the acquired image. Specifically, the controller 100 calculates the distance between the vehicle body and the road surface by using the ruts on the road surface included in the acquired image as feature points of the road surface. In step S3, the controller 100 estimates the amount of sinking of the vehicle's tires into the road surface based on the first distance and a previously acquired second distance. In step S4, the controller 100 acquires the vehicle's speed, tire angle, slip ratio, road surface gradient, and road surface moisture content. Furthermore, it is sufficient to obtain at least one of the following: the speed of vehicle 1, the tire angle of vehicle 1, the slip ratio of vehicle 1, the gradient of the road surface, and the moisture content of the road surface.

[0033] In step S5, the controller 100 calculates the risk of the vehicle getting stuck on the road surface based on the amount of sinking, the speed of the vehicle 1, the tire angle of the vehicle 1, the slip ratio of the vehicle 1, the gradient of the road surface, and the amount of moisture on the road surface. In step S6, the controller 100 notifies the occupants of the vehicle 1 of the risk. In step S7, the controller 100 determines whether the vehicle 1 is in the stuck avoidance mode. If it determines that the vehicle 1 is in the stuck avoidance mode, the controller 100 proceeds to step S8. If it determines that the vehicle is not in the stuck avoidance mode, the controller 100 terminates the control flow. In step S8, the controller 100 controls the drive torque according to the risk. For example, the controller 100 sets an upper limit on the wheel rotation speed according to the risk and calculates the drive torque based on the upper limit on the wheel rotation speed. A control signal including the calculated drive torque is output to the drive control device 15.

[0034] Furthermore, in this embodiment, the estimated amount of sinking may include the amount of sinking on the rear side, where the rear tire of the vehicle 1 sinks into the road surface, and the amount of sinking on the front side, where the front tire of the vehicle 1 sinks into the road surface. The aforementioned first distance is calculated as the distance between the vehicle body of the vehicle 1 and the road surface, which is calculated from the rear camera. Therefore, by reflecting the condition of the front part of the vehicle body of the vehicle 1, the risk of the entire vehicle body of the vehicle 1 getting stuck can be calculated more accurately. The following describes an embodiment for estimating the amount of sinking on the rear side and the amount of sinking on the front side.

[0035] The image acquisition unit 101 acquires images from the rear camera of the road surface in the direction opposite to the direction of travel of the vehicle 1. The image acquisition unit 101 also acquires images of the road surface in the direction of travel of the vehicle 1. For each acquired image, the image acquisition unit 101 extracts feature points contained in the image. The specific method of image acquisition by the image acquisition unit 101 is described in the above explanation regarding the functions of the image acquisition unit 101 as appropriate.

[0036] The distance calculation unit 102 calculates a first distance between the rear of the vehicle 1 and the road surface based on the image captured by the rear camera. Furthermore, if characteristic points of the road surface can be extracted from the image captured by the front camera, the distance calculation unit 102 calculates a third distance between the front of the vehicle 1 and the road surface based on the image captured by the front camera. A case where characteristic points of the road surface can be extracted from the image captured by the front camera is, for example, when another vehicle is traveling in the direction of travel of the vehicle 1, and ruts have been created in the direction of travel of the vehicle 1 as a result of the other vehicle's movement. The specific method for calculating the first and third distances is appropriately based on the previously described function of the distance calculation unit 102.

[0037] The settlement estimation unit 103 estimates the amount of settlement on the rear side, where the rear tire sinks into the road surface, based on the first distance and the second distance. The settlement estimation unit 103 also estimates the amount of settlement on the front side, where the front tire sinks into the road surface, based on the third distance and the second distance. The specific method for estimating the rear and front settlement amounts is appropriately based on the previously described function of the settlement estimation unit 103.

[0038] The risk calculation unit 104 calculates the risk based on the amount of sinking on the rear and front sides. For example, the risk calculation unit 104 may compare the amount of sinking on the rear side and the amount of sinking on the front side and calculate the risk based on the amount of sinking that is greater. Also, the risk of the vehicle 1 getting stuck due to the front tires sinking is different from the risk of the vehicle 1 getting stuck due to the rear tires sinking, with the risk of the vehicle 1 getting stuck due to the front tires sinking being higher. Therefore, the relationship between the amount of sinking on the front side and the risk is different from the relationship between the amount of sinking on the rear side and the risk. The risk calculation unit 104 calculates the risk separately according to the amount of sinking on the front side and the amount of sinking on the rear side. For example, the risk calculation unit 104 calculates the risk on the front side by referring to the relationship between the amount of sinking on the front side and the risk. Also, the risk calculation unit 104 calculates the risk on the rear side by referring to the relationship between the amount of sinking on the rear side and the risk. Then, the risk calculation unit 104 may compare the risk on the front side and the risk on the rear side and select the risk with the greater value. The specific method for calculating the risk is appropriately based on the above-mentioned explanation regarding the function of the risk calculation unit 104. Furthermore, the risk calculation unit 104 may calculate a lower risk if the image captured by the forward camera includes the tracks of another vehicle, compared to when the image captured by the forward camera does not include the tracks of another vehicle. This is because if there are tracks left by another vehicle in the direction of travel of the vehicle 1, and the vehicle 1 is traveling along those tracks, the risk of the vehicle 1 getting stuck is considered small.

[0039] As described above, in the vehicle control device and vehicle control method according to this embodiment, the controller acquires images captured by a rear camera that photographs the road surface in the direction opposite to the direction of travel of the vehicle, and based on the captured images, calculates a first distance between the vehicle body and the road surface, using the ruts created on the road surface by the vehicle's movement as feature points, and estimates the amount of sinking of the tires into the road surface based on the first distance and a second distance, which is previously acquired, between the vehicle body and the contact point of the vehicle's tires. This makes it possible to estimate the degree to which the vehicle's tires are sinking into the road surface based on the camera's captured images when the vehicle is traveling in a place where it is difficult to recognize feature points from the road surface image in the direction of travel.

[0040] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the rear camera is a camera located at the rear of the vehicle. This makes it easier to acquire images that include ruts on the road surface in the opposite direction to the vehicle's direction of travel.

[0041] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the controller notifies the occupants of the vehicle of the amount of sinking. This allows the occupants of the vehicle to understand the extent to which the vehicle's tires are sinking into the road surface.

[0042] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the controller calculates the risk of the vehicle getting stuck on the road surface based on the amount of sinking. This makes it possible to estimate the possibility of the vehicle getting stuck on the road surface.

[0043] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the controller calculates the risk based on at least one of the following: the vehicle's speed, the tire slip ratio, the steering angle of the vehicle, the gradient of the road surface, and the amount of moisture on the road surface. This allows for a more accurate estimation of the possibility of the vehicle getting stuck on the road surface.

[0044] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the controller stores the estimated amount of settlement while the vehicle is traveling on the road surface as an estimation history, and based on the estimation history, if it is estimated that the amount of settlement has decreased, it calculates the risk in such a way that the risk is lower than when the amount of settlement has not changed or when it is estimated that the amount of settlement has increased. This makes it possible to estimate the possibility of the vehicle getting stuck on the road surface more accurately.

[0045] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the controller notifies the occupants of the vehicle of the risks. This allows the occupants of the vehicle to understand the possibility of their vehicle getting stuck on the road surface.

[0046] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the controller controls the driving torque of the vehicle in a manner that reduces the risk, depending on the risk. This makes it possible to avoid the vehicle getting stuck.

[0047] Furthermore, in the vehicle control device and vehicle control method according to this embodiment, the first distance is the distance between the rear of the vehicle body and the road surface, the vehicle is equipped with a forward camera that photographs the road surface in the direction of travel, and the controller calculates a third distance between the front of the vehicle body and the road surface based on the image captured by the forward camera if feature points can be extracted from the image captured by the forward camera, estimates the amount of sinking on the rear side where the rear tire sinks into the road surface based on the first distance and the second distance, estimates the amount of sinking on the front side where the front tire sinks into the road surface based on the third distance and the second distance, and calculates the risk based on the amount of sinking on the rear and front sides. This makes it possible to estimate the possibility of the vehicle getting stuck on the road surface more accurately.

[0048] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of Symbols]

[0049] 1... Own vehicle 10... Vehicle control system 100... Controller 101...Image acquisition unit 102... Distance calculation unit 103... Settlement Estimation Section 104…Risk Calculation Department 105... Vehicle Control Unit 11…Camera

Claims

1. A vehicle control device equipped with a controller, The aforementioned controller, The rear camera captures images of the road surface in the opposite direction to the vehicle's direction of travel, and the rear camera captures the images it has taken. Based on the captured image, the ruts created on the road surface by the vehicle's movement are used as characteristic points to calculate a first distance between the vehicle's body and the road surface. A vehicle control device that estimates the amount of sinking of the tire into the road surface based on the first distance and a second distance, which has been previously acquired, between the vehicle body and the point of contact of the vehicle's tire.

2. A vehicle control device according to claim 1, The rear camera is a vehicle control device, which is a camera installed at the rear of the vehicle.

3. A vehicle control device according to claim 1 or 2, The aforementioned controller, A vehicle control device that notifies the occupants of the vehicle of the amount of sinking.

4. A vehicle control device according to claim 1 or 2, The aforementioned controller, A vehicle control device that calculates the risk of the vehicle getting stuck on the road surface based on the amount of subsidence.

5. A vehicle control device according to claim 4, The aforementioned controller, A vehicle control device that calculates the risk based on at least one of the following: the speed of the vehicle, the slip ratio of the tires, the steering angle of the vehicle, the gradient of the road surface, and the amount of moisture on the road surface.

6. A vehicle control device according to claim 4, The aforementioned controller, The amount of subsidence estimated while the vehicle is traveling on the road surface is stored as an estimated history. A vehicle control device that calculates the risk such that, based on the estimated history, if it is estimated that the amount of settlement has decreased, the risk is lower than if it is estimated that the amount of settlement has not changed or that the amount of settlement has increased.

7. A vehicle control device according to claim 4, The aforementioned controller, A vehicle control device that notifies the occupants of the vehicle of the aforementioned risk.

8. A vehicle control device according to claim 4, The aforementioned controller, A vehicle control device that controls the driving torque of the vehicle in accordance with the aforementioned risk so as to reduce the aforementioned risk.

9. A vehicle control device according to claim 4, The first distance is the distance between the rear part of the vehicle body and the road surface, The vehicle is equipped with a forward-facing camera that photographs the road surface in the direction of travel, The aforementioned controller, If feature points can be extracted from the image captured by the forward camera, a third distance between the front part of the vehicle body and the road surface is calculated based on the image captured by the forward camera. Based on the first distance and the second distance, the amount of sinking of the rear tire into the road surface is estimated. Based on the third distance and the second distance, the amount of sinking on the front side of the tire as it sinks into the road surface is estimated. A vehicle control device that calculates the risk based on the amount of settlement on the rear and front sides.

10. A vehicle control method performed by a controller, The aforementioned controller, The rear camera captures images of the road surface in the opposite direction to the vehicle's direction of travel, and the rear camera captures the images it has taken. Based on the captured image, the ruts created on the road surface by the vehicle's movement are used as characteristic points to calculate a first distance between the vehicle's body and the road surface. A vehicle control method for estimating the amount of sinking of the tire into the road surface based on the first distance and a second distance, which has been previously acquired, between the vehicle body and the point of contact of the vehicle's tire.

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