Gradient Recognition Device

Abstract

To provide a slope recognition device that accurately determines a change in a slope in a travel direction, with a simple configuration.SOLUTION: A slope recognition device 10 includes: a camera 1; a vanishing point calculation unit that calculates a position of a vanishing point in a camera image; a distance calculation part that calculates a distance from the own vehicle to a forward vehicle on the basis of the calculated position of the vanishing point and a position of a lower end part of the forward vehicle in the camera image; an area calculation unit that calculates an area of the forward vehicle in the camera image; and a determination unit 23 that determines whether a slope of a road surface changes in front of the own vehicle on the basis of the calculated distance and area. The determination unit 23 determines that the slope of the road surface changes in front of the own vehicle when a change amount of the distance calculated by the distance calculation unit is equal to or greater than a first predetermined value and a change amount of the area calculated by the area calculation unit is equal to or less than a second predetermined value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gradient recognition device that recognizes changes in the gradient of a road surface in the traveling direction of a vehicle. [Background technology]

[0002] A known example of this type of device is one that, when a camera image includes a vehicle ahead, calculates a predicted position where the bottom of the vehicle ahead is expected to be located assuming that the gradient of the road is constant, determines whether the difference between this predicted position and the position of the bottom of the vehicle ahead detected from the camera image exceeds a threshold, and determines that a gradient exists if it is determined that the difference exceeds the threshold (see, for example, Patent Document 1). In the device described in Patent Document 1, the predicted position is calculated based on the position of the vanishing point identified from the camera image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-79182 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the device described in Patent Document 1, it may be difficult to accurately recognize changes in gradient in situations where the position of the vanishing point changes due to, for example, the vehicle moving up and down. [Means for solving the problem]

[0005] A gradient recognition device according to one aspect of the present invention is provided on a host vehicle and includes: an imaging unit that captures an image of a predetermined area including a forward vehicle located in front of the host vehicle; a vanishing point calculation unit that calculates the position of a vanishing point in the image acquired by the imaging unit; a distance calculation unit that calculates the distance from the host vehicle to the forward vehicle based on the position of the vanishing point calculated by the vanishing point calculation unit and the position of the lower end of the forward vehicle in the image acquired by the imaging unit; an area calculation unit that calculates the area of the forward vehicle in the image acquired by the imaging unit; and a determination unit that determines whether the gradient of the road surface is changing ahead of the host vehicle based on the distance calculated by the distance calculation unit and the area calculated by the area calculation unit. The determination unit determines that the gradient of the road surface is changing ahead of the host vehicle when the amount of change or rate of change in the distance calculated by the distance calculation unit is equal to or greater than a first predetermined value and the amount of change or rate of change in the area calculated by the area calculation unit is equal to or less than a second predetermined value. [Effects of the Invention]

[0006] According to the present invention, it is possible to accurately recognize changes in gradient even in situations where the position of the vanishing point changes. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a side view of a vehicle having a gradient recognition device according to an embodiment of the present invention; [Figure 2] 1 is a diagram showing an example of a driving scene to which a gradient recognition device according to an embodiment of the present invention is applied; [Figure 3] FIG. 1 is a block diagram showing a configuration of a main part of a gradient recognition device according to an embodiment of the present invention. [Figure 4] 4 is a flowchart showing an example of processing executed by the controller of FIG. 3; [Figure 5] FIG. 2 is a diagram showing a modification of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 5. A gradient recognition device according to an embodiment of the present invention is configured to recognize the gradient of the road surface ahead of the vehicle based on an image taken by a camera mounted on the front of the vehicle and capturing an image in the direction of travel of the vehicle.

[0009] FIG. 1 is a side view of a vehicle 100 equipped with a gradient recognition device according to an embodiment of the present invention. As shown in FIG. 1, a camera 1 is provided at the front of the vehicle 100, more specifically near the windshield at the top of the vehicle interior. The camera 1 is a monocular camera having an imaging element (image sensor) such as a CCD or CMOS. The camera 1 continuously captures images of the space ahead of the vehicle 100 and acquires images (camera images) of the target object.

[0010] 1 shows the vertical angle of view θ of the camera 1 and an imaging area AR. The imaging area AR includes, as an object to be imaged by the camera 1, leading vehicles 101 (101_1, 101_2) traveling ahead of the host vehicle 100. The preceding vehicles 101_1, 101_2 illustrate a case where they travel on different road surfaces. That is, the leading vehicle 101_1 travels on the same road surface 200 (a road surface on the same horizontal plane) as the road surface 200 on which the host vehicle 100 is traveling, and is located at the same height as the host vehicle 100. On the other hand, the leading vehicle 101_2 travels on a road surface 201 that slopes upward toward the front, and is located above the host vehicle 100.

[0011] 2 is a diagram showing an example of a driving scene to which the gradient recognition device according to this embodiment is applied. This diagram shows a view (camera image) from camera 1 of host vehicle 100. FIG. 2 includes host vehicle image 100a showing the front end of the hood of host vehicle 100, forward vehicle image 101a showing forward vehicle 101, road surface images 200a and 201a showing road surfaces 200 and 201, respectively, lane line images 211a and 212a showing left and right lane lines 211 and 212, and lane image 210a showing driving lane 210.

[0012] As shown in Fig. 2, the host vehicle 100 is traveling in a lane 210 defined by a pair of left and right dividing lines 211, 212 extending in the traveling direction of the host vehicle 100. In front of the road surface 200 on which the host vehicle 100 is traveling, there is an uphill road surface 201. In front of the host vehicle 100, there is a leading vehicle 101 (corresponding to the leading vehicle 101_1 in Fig. 1) traveling on the road surface 200. Points P1 and P2 in the figure are vanishing points.

[0013] Vanishing points P1 and P2 are the intersections (points at infinity) obtained when the left and right lane markings 211 and 212, sidewalk blocks, guardrails, etc. are extended in straight lines. When the road gradient is constant, the vanishing points converge to a single point on the image. In FIG. 2, the road gradient changes midway and becomes an uphill slope, so multiple vanishing points P1 and P2 are obtained. That is, there is vanishing point P1, which is identified by lane markings, etc. on the road surface 200 on which the host vehicle 100 is traveling, and vanishing point P2, which is identified by lane markings, etc. on the road surface 201 ahead of the host vehicle 100. Note that when a vanishing point cannot be obtained due to an obstacle, a fork in the road, or other reasons, the most recent vanishing point identified up until that point can be used.

[0014] The gradient recognition device according to this embodiment has a function of calculating the distance from the host vehicle 100 to the vehicle 101 ahead, i.e., the inter-vehicle distance, based on camera images. The inter-vehicle distance is calculated as follows: First, a vanishing point P1 is identified by extending a lane marking or the like on the road surface on which the host vehicle 100 is traveling. Next, a length y1 from the vanishing point P1 to the ground contact surface of the vehicle 101 ahead on the camera image is calculated. That is, in an XY coordinate system in which the horizontal direction of the camera image is the X axis and the vertical direction is the Y axis, the length y1 is calculated by subtracting the y coordinate of the ground contact surface from the y coordinate of the vanishing point P1.

[0015] The length y1 on the camera image correlates with the inter-vehicle distance. In other words, the contact patch is located below the vanishing point P1, and the shorter the length y1, the longer the inter-vehicle distance. Therefore, the inter-vehicle distance can be calculated by substituting the length y1 into the equation that shows the correlation between the length y1 and the inter-vehicle distance. The calculated inter-vehicle distance is treated as the actual inter-vehicle distance and is used, for example, when following a vehicle ahead while maintaining the inter-vehicle distance at a target inter-vehicle distance.

[0016] However, when the preceding vehicle 101 is traveling on a road surface 201 that has an upward slope relative to the road surface 200, the contact patch moves above the vanishing point P1. As a result, if the inter-vehicle distance is calculated using the distance y1, the inter-vehicle distance cannot be calculated accurately, making it difficult to properly follow the preceding vehicle 101. Similarly, when the road ahead of the host vehicle 100 is not an upslope but a downslope, the inter-vehicle distance cannot be calculated accurately. Therefore, in this embodiment, a configuration is made in which changes in the gradient ahead of the host vehicle 100 are recognized as follows, and the inter-vehicle distance is calculated taking the change in gradient into account.

[0017] 3 is a block diagram showing the configuration of the main parts of a gradient recognition device 10 according to an embodiment of the present invention. As shown in FIG. 3, the gradient recognition device 10 includes a camera 1, a controller 20, and a traveling actuator 2.

[0018] The traveling actuator 2 is an actuator whose drive is controlled when the host vehicle 100 travels, particularly when the host vehicle 100 travels following the preceding vehicle 101 while maintaining a predetermined distance between the host vehicle 100 and the preceding vehicle 101 according to the vehicle speed. When the traveling drive source is an engine, the traveling actuator 2 includes a throttle actuator that adjusts the opening of a throttle valve (throttle opening) of the engine. When the traveling drive source is a traveling motor, the traveling motor is included in the traveling actuator 2. A brake actuator that operates the braking device of the host vehicle 100 is also included in the traveling actuator 2. A steering actuator that drives a steering device may also be included in the traveling actuator 2.

[0019] The controller 20 is configured to include a computer having a CPU, ROM, RAM, and other peripheral circuits such as an I / O interface. The controller 20 executes predetermined processing based on the image signal from the camera 1, determines whether or not there is a change in the gradient of the road surface ahead of the vehicle 100, and controls the driving actuator 2 according to the determination result. The controller 20 has, as its functional configuration, a calculation unit 21, a memory unit 22, a determination unit 23, and a driving control unit 24.

[0020] Based on the camera image, the calculation unit 21 calculates the vanishing points P1 and P2, the inter-vehicle distance D between the host vehicle 100 and the preceding vehicle 101, and the area A of the rear surface of the preceding vehicle 101. That is, the calculation unit 21 functions as a vanishing point calculation unit, a distance calculation unit, and an area calculation unit.

[0021] More specifically, the vanishing point calculation unit calculates the coordinates (xy coordinates) of vanishing point P1 on the camera image, taking the intersection of straight lines extending upward (toward the traveling direction of vehicle 100) along lane markings on the left and right sides of vehicle 100 as vanishing point P1, as shown in Fig. 2. Vanishing point P1 can be calculated using a Hough transform or the like. When the gradient of the road changes midway, the vanishing point calculation unit calculates multiple vanishing points P1 and P2.

[0022] The distance calculation unit calculates the length y1 in the Y-axis direction from the position of the vanishing point P1 calculated by the vanishing point calculation unit to the ground contact surface of the forward vehicle 101 in the camera image. Furthermore, the distance calculation unit calculates the inter-vehicle distance D from the host vehicle 100 to the forward vehicle 101 corresponding to the length y1, using the relationship between the length y1 in the Y-axis direction of the camera image and the inter-vehicle distance D, which is stored in advance in the storage unit 22.

[0023] The area calculation unit calculates the area A of the rear surface of the forward vehicle 101 in the camera image. For example, as shown in FIG. 2, a rectangular figure F is defined by the ground contact surface, top surface, and left and right side surfaces of the forward vehicle 101. The area calculation unit calculates the area of figure F by multiplying the length in the Y-axis direction from the ground contact surface to the top surface of the forward vehicle 101 by the length in the X-axis direction from the left surface to the right surface. The area of figure F is treated as the area A of the rear surface of the forward vehicle 101.

[0024] The storage unit 22 stores, in chronological order, the inter-vehicle distance D calculated by the inter-vehicle distance calculation unit and the area A calculated by the area calculation unit from the present time until a predetermined time ago. For example, as shown in FIG. 1, the predetermined time corresponds to the time required for the host vehicle 100 to reach a position (gradient change point) Pa where the preceding vehicle 101 starts traveling on a road surface 201 having a gradient different from that of the road surface 200 on which the host vehicle 100 is traveling, i.e., the time required for the host vehicle 100 and the preceding vehicle 101 to travel on a road surface 201 having the same gradient. Therefore, the longer the inter-vehicle distance D and the slower the vehicle speed, the longer the predetermined time. Note that a fixed time may be used as the predetermined time regardless of the inter-vehicle distance D and the vehicle speed. The predetermined time may also be the time required for the host vehicle 100 to travel a predetermined distance toward the preceding vehicle 101.

[0025] After calculating the amount of change and rate of change in area A, determination unit 23 determines whether or not a gradient exists ahead of vehicle 100 based on inter-vehicle distance D calculated by the distance calculation unit and area A calculated by the area calculation unit. Specifically, determination unit 23 first determines whether or not area A calculated by the area calculation unit is equal to or greater than predetermined value A1. This determination is made to prevent the amount of change and rate of change in area A from being erroneously determined to have increased if the amount of change and rate of change in area A are calculated when area A is less than predetermined value A1, that is, when the area is relatively small.

[0026] If it is determined that the area A is equal to or greater than a predetermined value, the determination unit 23 determines whether the change ΔD in the inter-vehicle distance D within a predetermined time calculated by the distance calculation unit is equal to or greater than a predetermined value ΔD1 and whether the change ΔA in the area A within a predetermined time calculated by the area calculation unit is equal to or less than a predetermined value ΔA1. This is a determination as to whether the gradient condition is met, and if the gradient condition is met, it is determined that the gradient will change.

[0027] That is, for example, as shown in Fig. 2, if the host vehicle 100 is traveling on a horizontal road surface 200 and the leading vehicle 101 is also traveling on the horizontal road surface 200, the amount of change Δy in the length y1 from the vanishing point P1 to the ground contact surface is small and less than a predetermined value Δy1. On the other hand, if the leading vehicle 101 is traveling on an uphill road surface 201 while the host vehicle 100 is traveling on the horizontal road surface 200, the ground contact surface of the leading vehicle 101 in the camera image moves upward, and the amount of change Δy in the length y1 becomes equal to or greater than the predetermined value Δy1. In this case, even if the leading vehicle 101 is traveling on the uphill road surface 201 as shown in Fig. 1, if the actual inter-vehicle distance does not change significantly, the amount of change ΔA in the area A of the rear surface of the leading vehicle 101 is small and less than the predetermined value ΔA1.

[0028] Taking this into consideration, the determination unit 23 determines whether ΔD≧D1 and ΔA≦ΔA1 are satisfied, i.e., whether the gradient condition is satisfied. If it is determined that the gradient condition is satisfied, the determination unit 23 determines that the gradient is changing in the traveling direction of the host vehicle 100. Alternatively, the determination unit 23 may determine whether the rate of change in the inter-vehicle distance D within a predetermined time calculated by the distance calculation unit is equal to or greater than a predetermined value and the rate of change in the area A within a predetermined time calculated by the area calculation unit is equal to or less than a predetermined value, thereby determining whether the gradient condition is satisfied. Alternatively, the determination unit 23 may calculate the changes ΔD and ΔA in the inter-vehicle distance D and area A without using the predetermined time as a condition, and determine that the gradient condition is satisfied when ΔD≧D1 and ΔA≦ΔA1 are satisfied.

[0029] When a command to follow the preceding vehicle 101 is issued, the driving control unit 24 controls the driving actuator 2 so that the actual inter-vehicle distance becomes the target inter-vehicle distance according to the vehicle speed. At this time, if the gradient condition is not met, the driving control unit 24 uses the inter-vehicle distance D calculated by the distance calculation unit as the actual inter-vehicle distance. On the other hand, if the determination unit 23 determines that the gradient condition is met, the driving control unit 24 uses the inter-vehicle distance D stored in the memory unit 22 before it is determined that the gradient condition is met (for example, immediately before the determination). This makes it possible to prevent an erroneous calculation of the actual inter-vehicle distance, and enables good follow-up driving.

[0030] 4 is a flowchart showing an example of processing executed by the controller 20 in accordance with a predetermined program. The processing shown in this flowchart is started when a preceding vehicle 101 is recognized in a camera image by processing such as pattern matching, and is repeated at predetermined intervals.

[0031] First, in step S1, the image signal from camera 1 is read. Next, in step S2, a vanishing point P1 is calculated based on the camera image. Next, in step S3, a length y1 from vanishing point P1 to the ground contact surface of the preceding vehicle 101 is calculated, and an inter-vehicle distance D according to the length y1 is calculated. Next, in step S4, an area A of the rear surface (figure F) of the preceding vehicle 101 is calculated based on the camera image. Next, in step S5, the inter-vehicle distance D calculated in step S3 and the area A calculated in step S4 are stored in memory unit 22. In this case, the inter-vehicle distance D and area A from the present time up to a predetermined time ago are stored, and data before the predetermined time is sequentially erased.

[0032] Next, in step S6, it is determined whether the area A calculated in step S4 is equal to or greater than a predetermined value A1. If the result in step S6 is affirmative, the process proceeds to step S7, and if the result is negative, the process ends. In step S7, it is determined whether the amount of change ΔD in the inter-vehicle distance D within a predetermined time stored in the memory unit 22 is equal to or greater than a predetermined value ΔD1 and whether the amount of change ΔA in the area A within the predetermined time is equal to or less than a predetermined value ΔA1. If the result in step S7 is affirmative, the process proceeds to step S8, and if the result is negative, the process ends. In step S8, it is determined that the gradient is changing ahead of the vehicle 100, and the process ends.

[0033] The operation of the gradient recognition device 10 according to this embodiment can be summarized as follows: When the host vehicle 100 is traveling following the preceding vehicle 101, a vanishing point P1 (FIG. 2) is calculated based on the camera image, and the inter-vehicle distance D is calculated based on the length y1 from the vanishing point P1 to the ground contact surface of the preceding vehicle 101 (steps S2 and S3). This makes it possible to calculate the inter-vehicle distance D with an inexpensive configuration using the monocular camera 1. At this time, the driving actuator 2 is controlled so that the inter-vehicle distance D becomes a target inter-vehicle distance according to the vehicle speed.

[0034] During following travel, when the preceding vehicle 101 starts traveling on an uphill road surface 201, the length y1 to the ground contact surface of the preceding vehicle 101 changes, and the amount of change ΔD in the inter-vehicle distance D becomes equal to or greater than a predetermined value ΔD1. On the other hand, since the actual change in the inter-vehicle distance is small, when the area A of the rear surface of the preceding vehicle 101 is equal to or greater than the predetermined value A1, the amount of change ΔA in the area A of the rear surface of the preceding vehicle 101 is equal to or less than the predetermined value ΔA1. This allows the change in the gradient ahead of the host vehicle 100 to be recognized (step S7 → step S8).

[0035] When a change in gradient is recognized, the vehicle follows the preceding vehicle 101, using the inter-vehicle distance D calculated before the change in gradient was recognized as the actual inter-vehicle distance. This makes it possible to prevent following using an incorrect inter-vehicle distance D. As a result, it is possible to prevent a decrease in traffic smoothness while improving traffic safety without disrupting the surrounding traffic flow. When a change in gradient is recognized, the driver may be notified of this information. This allows the driver to perform accelerator or brake operations without delay.

[0036] According to this embodiment, the following effects can be achieved. (1) The gradient recognition device 10 is provided on the host vehicle 100 and includes a camera 1 that captures an image of a predetermined shooting area AR including a preceding vehicle 101 located in front of the host vehicle 100; a vanishing point calculation unit (calculation unit 21) that calculates the position of a vanishing point P1 in the image obtained by the camera 1; a distance calculation unit (calculation unit 21) that calculates the inter-vehicle distance D from the host vehicle 100 to the preceding vehicle 101 based on the position of the vanishing point P1 calculated by the vanishing point calculation unit and the position of the lower end of the preceding vehicle 101 in the image obtained by the camera 1; an area calculation unit (calculation unit 21) that calculates the area A of the preceding vehicle 101 in the image obtained by the camera 1; and a determination unit 23 that determines whether the gradient of the road surface changes in front of the host vehicle 100 based on the inter-vehicle distance D calculated by the distance calculation unit and the area A calculated by the area calculation unit (Figure 3). The determination unit 23 determines that the gradient of the road surface ahead of the vehicle 100 is changing when the change ΔD in the inter-vehicle distance D calculated by the distance calculation unit is equal to or greater than a predetermined value ΔD1 and the change ΔA in the area A calculated by the area calculation unit is equal to or less than a predetermined value ΔA1 (Figure 4).

[0037] This allows for accurate determination of changes in road gradient even in situations where the position of vanishing point P1 changes due to the vehicle's vertical movement. Furthermore, because gradient changes are determined using only camera images, gradient changes can be accurately determined with an inexpensive configuration. Furthermore, when there is a change in inter-vehicle distance D based on vanishing point P, it can be determined that the inter-vehicle distance D has not actually changed but has instead changed due to the change in gradient, preventing vehicle control such as following a vehicle from being performed using an incorrect inter-vehicle distance D.

[0038] (2) The determination unit 23 further determines whether the area A calculated by the area calculation unit is equal to or greater than a predetermined value A1, and when the area A calculated by the area calculation unit is equal to or greater than the predetermined value A1, determines whether the gradient of the road surface ahead of the vehicle 100 is changing (FIG. 4). This determines whether the gradient condition is met, such as whether the amount of change ΔA in the area A is equal to or less than the predetermined value ΔA1 when the area A is large, so that it is possible to accurately determine whether the gradient of the road surface is changing.

[0039] The above embodiment can be modified in various ways. Some modified examples will be described below. In the above embodiment, the satisfaction of the gradient condition is determined on the condition that the area A is equal to or greater than a predetermined value A1. However, the satisfaction of the gradient condition may also be determined on the condition that multiple vanishing points are calculated. That is, when a gradient exists ahead of the host vehicle 100, multiple vanishing points P1, P2 are calculated as shown in FIG. 2. Taking this into consideration, when multiple vanishing points P1, P2 are calculated by the vanishing point calculation unit, it may be determined whether the gradient of the road surface ahead of the host vehicle 100 changes. This makes it possible to more accurately determine whether the gradient has changed.

[0040] In the above embodiment, when an upward gradient exists ahead of the host vehicle 100, an example is shown in which the presence or absence of a gradient change (presence or absence of a gradient change point Pa) is determined based on the amount of change ΔD in the distance D calculated by the distance calculation unit and the amount of change ΔA in the area A calculated by the area calculation unit, but the presence or absence of a gradient change can also be determined in a similar manner when a downward gradient exists ahead of the host vehicle 100. As shown in Fig. 5, the presence or absence of a gradient change can also be determined in a similar manner when the host vehicle 100 is traveling on a road surface 201 having a gradient and the preceding vehicle 101 is traveling on a level road surface 200.

[0041] In the above embodiment, the camera serving as the imaging unit is mounted on the upper front portion of the vehicle interior. However, the mounting position of the imaging unit is not limited to the above, as long as an image of a predetermined area including a preceding vehicle located ahead of the host vehicle is captured. In the above embodiment, the determination unit 23 determines that the gradient of the road surface changes (there is a gradient change point Pa) ahead of the host vehicle 100 when the change amount ΔD of the distance D within a predetermined time calculated by the distance calculation unit is equal to or greater than a predetermined value (first predetermined value) and the change amount ΔA of the area A within a predetermined time calculated by the area calculation unit is equal to or less than a predetermined value ΔA1 (second predetermined value). However, the determination unit 23 may determine that the gradient of the road surface changes ahead of the host vehicle 100 when the change rate of the distance D within a predetermined time calculated by the distance calculation unit is equal to or greater than the first predetermined value and the change rate of the area A within a predetermined time calculated by the area calculation unit is equal to or less than a second predetermined value. Therefore, the first predetermined value and the second predetermined value are not limited to those described above. Furthermore, the amount and rate of change of the distance D and the area A may be calculated without imposing a condition within a predetermined time.

[0042] In the above embodiment, when the host vehicle 100 is following the preceding vehicle 101, it is determined whether or not the gradient of the road surface ahead of the host vehicle 100 is changing, but it may also be determined whether or not the gradient is changing when a preceding vehicle is present even when the host vehicle 100 is not following the preceding vehicle 101. In the above embodiment, following the preceding vehicle is performed using the following vehicle distance information stored in the storage unit 22 before it is determined that the gradient will change, but the following vehicle distance information may also be used for driving control other than following the preceding vehicle.

[0043] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modifications as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other. [Explanation of symbols]

[0044] 1 camera, 10 gradient recognition device, 20 controller, 21 calculation unit, 22 storage unit, 23 determination unit, 100 host vehicle, 101 forward vehicle

Claims

1. an imaging unit provided in the host vehicle for imaging a predetermined area including a preceding vehicle located in front of the host vehicle; a vanishing point calculation unit that calculates the position of a vanishing point in the image obtained by the imaging unit; a distance calculation unit that calculates a distance from the host vehicle to the forward vehicle based on the position of the vanishing point calculated by the vanishing point calculation unit and the position of a lower end of the forward vehicle in the image obtained by the imaging unit; an area calculation unit that calculates an area of the forward vehicle in the image obtained by the imaging unit; a determination unit that determines whether or not a gradient of a road surface ahead of the host vehicle changes based on the distance calculated by the distance calculation unit and the area calculated by the area calculation unit, The gradient recognition device is characterized in that the determination unit determines that the gradient of the road surface is changing ahead of the vehicle when the amount of change or rate of change of the distance calculated by the distance calculation unit is equal to or greater than a first predetermined value and the amount of change or rate of change of the area calculated by the area calculation unit is equal to or less than a second predetermined value.

2. 2. The gradient recognition device according to claim 1, The determination unit further determines whether the area calculated by the area calculation unit is equal to or greater than a predetermined value, and when the area calculated by the area calculation unit is equal to or greater than the predetermined value, determines whether the gradient of the road surface ahead of the vehicle is changing.

3. 3. The gradient recognition device according to claim 1, The gradient recognition device is characterized in that the judgment unit further determines whether multiple vanishing points have been calculated by the vanishing point calculation unit, and when multiple vanishing points are calculated by the vanishing point calculation unit, determines whether the gradient of the road surface changes in front of the vehicle.

Images