Vehicle route guidance method and device

Abstract

When encountering a large difference in gradient, such as on a downhill slope at the exit of a parking lot, the lower front end of a vehicle's bumper can scrape against the road surface and become damaged. [Solution] When the vehicle's route guidance system includes a first surface on the near side and a second surface on the far side, where the relative gradients change, it calculates the gradient difference between the first surface and the second surface, calculates the maximum gradient the vehicle can pass through, and determines whether the underside will be damaged if the vehicle continues straight, based on these gradient differences and the maximum passable gradient. If it is determined that damage will occur, a text box 41 with a warning message will pop up on the vehicle's IVI 21 screen, and an audible notification will be given simultaneously. The area of ​​the road surface that the underside of the vehicle would come into contact with if it were to pass straight is displayed as a narrow, elliptical area 42 in a conspicuous color such as red.

Description

Technical Field

[0001] This invention relates to a route guidance method and a route guidance device for guiding the route of a vehicle on a passage having a gradient difference, such as an entrance or exit of a parking lot.

Background Art

[0002] Patent Document 1 discloses a technique for guiding a route within a parking lot after determining an optimal exit in consideration of the moving cost to the final destination in a parking lot having a plurality of entrances and exits as part of a so-called car navigation system.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, the road surface at the entrance or exit of a parking lot is often an inclined surface with a relatively large gradient, and there may be a large gradient difference (in other words, a relative gradient) between the road surface at the entrance or exit and the road outside the parking lot. In addition, on roads within a facility where driving at a low speed is assumed, there may be inclined roads with a large gradient in addition to the entrance and exit. In such a case, a vehicle with a low vehicle height may rub the lower part of the vehicle against the road surface.

Means for Solving the Problems

[0005] This invention is a method for guiding the route of a vehicle when the route on which the host vehicle plans to travel includes a first surface on the front side and a second surface on the rear side where the gradient changes relatively, obtaining route gradient information regarding the relative gradient of the first surface with respect to the second surface, obtaining host vehicle information regarding the maximum passable gradient of the host vehicle, Based on the above route gradient information and the above vehicle information, it is determined whether the underside of the vehicle will be damaged when moving from the first surface to the second surface. If damage is deemed likely, the driver will be notified in advance.

[0006] For example, if the first surface is a steep downhill slope and the second surface is a horizontal surface, the lower tip of the front bumper may scrape against the road surface. Similarly, if the first surface is a steep uphill slope and the vehicle is moving towards a downhill or horizontal second surface, the underside of the vehicle may scrape against the road surface. In such cases, the driver will be notified in advance that the underside of the vehicle may be damaged. [Effects of the Invention]

[0007] According to this invention, if a low-clearance vehicle is at risk of damage to its underside at the entrance or exit of a parking lot with a slope, the driver will be notified in advance, allowing them to drive safely and avoid damage. [Brief explanation of the drawing]

[0008] [Figure 1] An explanatory diagram showing the movement of a vehicle from an inclined first surface to a horizontal second surface. [Figure 2] A flowchart showing the processing flow of the first embodiment. [Figure 3] An explanatory diagram showing an example of a display in the first embodiment of the vehicle's IVI (In-Vehicle Inspection and Visual Indicator). [Figure 4] A diagram illustrating the maximum gradient a vehicle can traverse. [Figure 5] An explanatory diagram showing the case where the first surface and the second surface are convex. [Figure 6] An explanatory diagram illustrating the maximum passable gradient when the first and second surfaces are convex. [Figure 7] A flowchart showing the processing flow of the second embodiment. [Figure 8] A diagram illustrating the recommended route, which proceeds diagonally. [Figure 9] An explanatory diagram showing an example of a display in the second embodiment of the vehicle's IVI (In-Vehicle In-Vibration) system. [Modes for carrying out the invention]

[0009] An embodiment of this invention will be described in detail below with reference to the drawings. The vehicle in this embodiment is equipped with a route guidance device, also known as a car navigation system, which provides route guidance to a set destination. In cases where a destination is set in a relatively large parking lot, such as a shopping mall parking lot, or where a store within the parking lot is set as a waypoint, the route may be set to pass through the entrance or exit of the parking lot, which has a slope. Although the slope of parking lot entrances and exits is regulated by law, there is a concern that the underside of a low-riding vehicle (for example, the lower surface of the front bumper tip or the underside of the underside between the wheelbases) may scrape against the road surface and be damaged.

[0010] Figure 1 shows an example of such a change in road surface gradient. In this example, the route that vehicle 10 is scheduled to travel includes the exit of a parking lot, which includes a first surface 1 on the near side in the direction of travel that is downhill, and a second surface 2 on the far side in the direction of travel that is roughly horizontal and connects to a public road outside the parking lot. Therefore, vehicle 10 will proceed from the first surface 1 to the second surface 2 in a manner that crosses the boundary 3 between the first surface 1 and the second surface 2. In this example, if the vehicle 10 has a low ride height, the lower part of the front bumper tip (the part indicated by reference numeral 11) is likely to come into contact with the road surface.

[0011] In the first embodiment, if the system determines that there is a high risk of damaging the underside of the vehicle 10 if it proceeds straight from the first surface 1 to the second surface 2, this fact is communicated to the driver in advance. Conversely, if there is no risk of damaging the underside even if it proceeds straight, this fact is also communicated to the driver.

[0012] In this invention, the terms "first surface" and "second surface" do not mean a perfectly flat plane; it is sufficient that the two road surfaces, front and rear, are continuous with different gradients. Furthermore, a clear boundary 3 is not necessarily required; the first surface and the second surface, with their different gradients, may be smoothly continuous.

[0013] FIG. 2 is a flowchart showing the flow of the route guidance process of the first embodiment. In step 1, it is repeatedly determined whether the host vehicle 10 has reached a position approaching a downhill (that is, the first surface 1) existing on the planned route. For example, if it is determined based on the map information of the car navigation system that the host vehicle 10 has reached a position approaching a downhill, the process proceeds to step 2 and subsequent steps. Here, since it targets a downhill with a low speed such as the exit of a parking lot, it is possible not to perform the determination in step 1 during normal driving at a certain vehicle speed or higher.

[0014] In step 2, regarding the exit to be traveled next, route gradient information regarding the relative gradient of the first surface 1 with respect to the second surface 2 as shown in FIG. 1 (in other words, the gradient difference θ1 between the two) is acquired. The route gradient information may be obtained from this map information, for example, when the map information of the car navigation system includes gradient information, or as a so-called connected car, information may be acquired from a cloud server via a wireless communication network, or further, as will be described later, the gradient difference may be detected or measured in the host vehicle 10.

[0015] In step 3, host vehicle information regarding the maximum passable gradient θ0 of the host vehicle is acquired. The maximum passable gradient θ0 is, in detail, as will be described later, but in one example, it is the magnitude of the gradient (gradient difference) at which the lower part 11 of the front bumper tip of the host vehicle 10 does not contact the road surface. This is, for example, based on the design value data of the vehicle, and basic information is stored in the memory of the host vehicle 10. When additional information such as the aging deterioration of the suspension is considered as will be described later, the maximum passable gradient is obtained by adding these information.

[0016] Next, in step 4, it is determined whether the lower part of the vehicle (for example, the lower part 11 of the front bumper tip) will be damaged if the host vehicle 10 travels straight from the first surface 1 to the second surface 2. This is basically based on a comparison of the magnitude of the gradient difference θ1 indicated by the route gradient information and the maximum passable gradient θ0 of the host vehicle 10.

[0017] If it is determined that there will be no damage even if the vehicle proceeds straight, proceed to Step 5 and guide the driver to slow down and pass through. For example, the driver may be notified by voice, or it may be presented as text or image display on the vehicle's IVI (In-Vehicle-Infotainment) described later. As a result, the driver can know in advance that it is possible to proceed straight and can proceed with confidence.

[0018] In Step 4, if it is determined that proceeding straight will damage the lower part of the vehicle, proceed to Step 6 and warn the driver in advance that proceeding straight will damage the lower part of the vehicle. This, like Step 5, may be notified to the driver by voice, or may be presented as text or image display on the vehicle's IVI. Further, in Step 7, guide the driver to bypass the exit ahead where there is a risk of damaging the lower part of the vehicle, for example, by using a bypass route that uses another exit.

[0019] FIG. 3 is an explanatory diagram showing an example of a display on the vehicle's IVI 21 when the lower part of the vehicle is damaged. When approaching an exit with a steep slope and it is difficult to proceed straight, a warning is displayed on the monitor in the vehicle interior, that is, on the IVI 21. FIG. 3 shows an example of the display screen of the IVI 21 during low-speed driving, having an around view screen 22 in the left half part and a camera display screen 23 of the front camera in the right half part. The around view screen 22 synthesizes images of a plurality of cameras provided in the vehicle and displays an image as if looking directly above the own vehicle 10 around the vehicle icon 24 indicating the own vehicle 10. The camera display screen 23 displays an image of the road surface in front of the vehicle acquired by the front camera, and at the upper part of this camera display screen 23, a text box 41 with a warning message such as "Warning: Continuing to move forward may highly likely damage the lower part of the front bumper" pops up and is displayed. This warning message is simultaneously notified by voice. Also, the area of the road surface where the bottom surface of the vehicle body will come into contact if it proceeds straight through is displayed by, for example, an elongated elliptical area 42 of a conspicuous color such as red.

[0020] In the example shown in Figure 3, no specific information is displayed on the around-view screen 22. However, for example, the vehicle icon 24 representing the vehicle 10 could be used to indicate which parts of the vehicle body are susceptible to damage. In the example above, for example, a yellow warning bar could be superimposed on the vehicle icon 24 near the front bumper.

[0021] Furthermore, if it is possible to proceed straight ahead in step 5 as described above, a pop-up text box 41 with a message such as "Please slow down and proceed" can be displayed and read aloud, as shown in the example in Figure 3. At the same time, an arrow icon indicating that it is possible to proceed straight ahead may also be displayed on the screen.

[0022] When approaching a parking lot exit with a steep slope, the system informs the driver in advance whether or not damage to the underside of the vehicle will occur, that is, whether or not it is possible to proceed straight. For example, if it indicates that it is possible to proceed straight, the driver can proceed with peace of mind. If it warns that damage to the underside of the vehicle will occur if it proceeds straight, the driver can take action such as turning back and following the suggested detour route, thereby avoiding damage to the underside of the vehicle.

[0023] Furthermore, although not shown in Figures 2 and 3, if it is determined that damage will occur to the underside of the vehicle, the system may also identify the location of the damage to the underside of the vehicle 10, determine the importance of the damaged area, and notify the driver in a manner that allows them to recognize this importance. For example, if a less important area is only slightly scraped, the driver may choose to proceed slowly diagonally from the first surface 1 to the second surface 2 instead of going straight, rather than detouring to another exit.

[0024] Next, with reference to Figure 4, the maximum passable gradient θ0 of the vehicle will be explained. As shown in Figure 4, the maximum passable gradient θ0 for downhill slopes is the magnitude of the gradient (gradient difference) at which the lower part 11 of the front bumper tip of the vehicle 10 does not come into contact with the road surface. If H is the ground clearance of the lower surface of the lower part 11 of the front bumper tip and F is the front overhang to the lower part 11 of the front bumper tip, then the maximum passable gradient θ0 is given by "tanθ0 = H / F".

[0025] Furthermore, it is desirable to consider the suspension's deterioration over time and the compression of the suspension due to vehicle tilting when determining the maximum passable gradient θ0. For example, if the suspension's compression length due to deterioration over time, compared to its new condition, is Sf for the front and Sr for the rear, and the wheelbase is W, then the vehicle tilt angle due to suspension deterioration, i.e., the nose dive angle φ, can be calculated as "tanφ=(Sf-Sr) / W". In this example, for simplicity, the difference in compression length between the left and right suspensions is not considered. Therefore, using this nose dive angle φ, the maximum passable gradient θ0 with deterioration over time can be expressed as "tanθ0=(H-Fsinφ-Sf) / Fcosφ".

[0026] The maximum passable gradient θ0 may be determined by, for example, a car dealership, by measuring the actual value under inclined conditions and storing this value in the vehicle's computer.

[0027] Next, referring again to Figure 1, one method for detecting or measuring gradient differences in the vehicle 10 will be explained. In recent years, automobiles are often equipped with distance measuring devices to measure the distance to an object, for example, as part of ADAS (Advanced Driver-Assistance Systems). Examples of distance measuring devices include LiDAR, millimeter-wave radar, stereo cameras, ultrasonic sensors, etc. Through these distance measuring devices, as shown in Figure 1, when the vehicle 10 is positioned on the first surface 1, the distance to the second surface 2 is measured in two directions having different inclination angles vertically, respectively, and the relative gradient can be calculated from these distances and their inclination angles. For example, if we measure distances using LiDAR in two directions, arrow A and arrow B, as shown in Figure 1, and denote the distance in direction A as La and the distance in direction B as Lb, then the relative gradient λ between the first surface 1 and the second surface 2 can be calculated using the inclination angle α in direction A and the inclination angle β in direction B when the vehicle is in a horizontal position, as "tanλ=(Lbsinβ-Lasinα) / (Lbcosβ-Lacosα)".

[0028] The present invention has been explained above using the example of a parking lot exit where the first surface 1 is a downhill slope and the second surface 2 is a horizontal surface. However, as shown in Figure 5, the present invention can also be applied when the first surface 101 and the second surface 102 are convex. On a convex road as shown in Figure 5, when crossing the peak portion which is the boundary 103 between the first surface 101 and the second surface 102, there is a risk that the lower part of the vehicle 10, more specifically the lower surface of the underside 33 between the front wheels 31 and the rear wheels 32, will scrape against the road surface. Therefore, as in the embodiments described above, if the difference in gradient between the first surface 101 and the second surface 102 is greater than the maximum gradient that the vehicle 10 can pass, it is determined that the lower part will be damaged if the vehicle continues straight, and a warning is given to the driver to that effect. For example, a warning similar to the example described in Figure 3 is possible. Furthermore, if the difference in gradient between the first surface 101 and the second surface 102 is smaller than the maximum gradient that the vehicle 10 can pass through, it is possible to proceed straight, and guidance indicating that it is possible to proceed straight can be provided as described above. In the example in Figure 5, the second surface 102 is almost horizontal, and the first surface 101 has a large gradient.

[0029] For a convex road like the one in Figure 5, the maximum passable gradient θ0 is given by "tan(θ0 / 2)=H / (W / 2)=2H / W" as shown in Figure 6, where H is the ground clearance of the underside of the body 33 and W is the wheelbase.

[0030] Furthermore, it is desirable to consider the suspension's deterioration over time and the suspension's compression due to vehicle tilting when determining the maximum passable gradient θ0. Using the nose dive angle φ due to the aforementioned deterioration over time, the maximum passable gradient θ0 with deterioration over time added can be expressed as "tan(θ0 / 2)=(H-(Sf+Sr) / 2) / (Wcosφ / 2)=(2H-Sf-Sr) / Wcosφ".

[0031] Furthermore, the detection or measurement of gradient differences using distance measuring devices such as LiDAR, as explained based on Figure 1, is also effective for the convex road shown in Figure 5. As shown by arrows A and B in Figure 5, the gradient difference can be calculated by measuring distances in two directions, A and B.

[0032] Next, a second embodiment of the present invention will be described using Figures 7 to 9. In the first embodiment described above, the driver is shown whether it is possible to proceed straight from the first surface 1, which has a large change in gradient, to the second surface 2. In the second embodiment, however, if it is determined that the underside of the vehicle will be damaged if it proceeds straight, the driver is guided to a recommended route that proceeds diagonally. Below, the second embodiment will be described using the example of proceeding through a parking lot exit where the first surface 1 is a downward slope and the second surface 2 is a horizontal surface, as shown in Figure 1.

[0033] Figure 7 is a flowchart showing the processing flow of route guidance in the second embodiment. Steps 1 to 5 are the same as steps 1 to 5 in the first embodiment shown in Figure 2. In step 1, it is repeatedly determined whether the vehicle 10 has reached a position where it will approach a downhill slope (i.e., the first surface 1) on the planned route. For example, if it is determined that the vehicle 10 has reached a position where it will approach a downhill slope based on the map information of the car navigation system, the process proceeds to step 2 and beyond. Note that, since this is intended for downhill slopes where the vehicle travels at low speeds, such as parking lot exits, the determination in step 1 can be omitted during normal driving at a certain speed or higher.

[0034] In step 2, route gradient information is obtained regarding the relative gradient (gradient difference θ1) of the first surface 1 to the second surface 2 for the exit to be reached. Route gradient information can be obtained, for example, from map information of a car navigation system or a cloud server, or, as mentioned above, the gradient difference may be detected or measured in the vehicle 10 itself.

[0035] In step 3, vehicle information regarding the maximum passable gradient θ0 of the vehicle is obtained. As mentioned above, the maximum passable gradient θ0 is the magnitude of the gradient (gradient difference) at which the lower tip 11 of the front bumper of the vehicle 10 does not come into contact with the road surface, in the example of a downhill slope. This basic information is stored in the memory of the vehicle 10, for example, based on the vehicle's design value data. As mentioned above, it is desirable to consider the deterioration of the suspension over time.

[0036] In step 4, it is determined whether the underside of the vehicle (for example, the lower part of the front bumper tip 11) will be damaged if the vehicle 10 were to travel straight from the first surface 1 to the second surface 2. This is basically done by comparing the magnitude of the gradient difference θ1 indicated by the path gradient information with the maximum passable gradient θ0 of the vehicle 10. If it is determined that no damage will occur, the process proceeds to step 5, where the driver is instructed to reduce speed and proceed. This is as described above in the first embodiment.

[0037] In step 4, if it is determined that proceeding straight will damage the underside of the vehicle, the system proceeds to step 16 or later, and provides guidance on a recommended route. In step 16, multiple candidate routes that proceed diagonally are extracted. As shown in Figure 8 below, the candidate routes should include at least a first route AC that detours to the right from the current position and proceeds diagonally from the first surface 1 to the second surface 2, and a second route DB that detours to the left from the current position and proceeds diagonally from the first surface 1 to the second surface 2. In one embodiment, the first route AC and the second route DB are extracted as candidate routes.

[0038] Then, in the next step 17, the incline angle ∠ACE of the first route AC and the incline angle ∠DBF of the second route BD are compared. If the incline angle ∠ACE of the first route AC is smaller, the first route is selected as the provisional recommended route (step 18); otherwise, the second route BD is selected as the provisional recommended route (step 19). Next, in step 20, it is determined whether the underside of the vehicle will be damaged when proceeding along the provisional recommended route selected in steps 18 and 19. This is basically done by comparing the incline angle (∠ACE or ∠DBF) of the selected provisional recommended route with the maximum passable gradient θ0.

[0039] If it is determined in step 20 that the underside of the vehicle will not be damaged, proceed to step 21 and guide the driver to the provisional recommended route selected in steps 18 and 19 as the final recommended route. If it is determined in step 20 that the underside of the vehicle will be damaged, proceed to step 22 and guide the driver to turn back. In other words, a detour route that bypasses the exit in question and uses another exit will be presented as the recommended route.

[0040] Figure 8 is an explanatory diagram of a recommended route that proceeds diagonally. Figure 8 simplifies the principle for determining the recommended route, assuming that the first surface 1 and the second surface 2 are both smooth planes, and that the second surface 2 is a horizontal plane, with the first surface 1 inclined with respect to this horizontal plane, the second surface 2, at a certain gradient. In the illustrated example, the first surface 1 is trapezoidal. Route MN in the figure is an example where the vehicle 10 proceeds straight down the first surface 1, which is a downhill slope. Point O is the point where a perpendicular line is drawn from point M to the horizontal plane (second surface 2), and ∠MON corresponds to the gradient difference θ1 mentioned above. If this ∠MON is greater than the maximum passable gradient θ0 of the vehicle 10, there is a risk of damaging the lower part of the vehicle. Therefore, two candidate routes are determined, for example, based on map information: a first route AC that detours from the current position to point A on the right and proceeds diagonally across the second surface 2, and a second route DB that detours from the current position to point D on the left and proceeds diagonally across the second surface 2. Point E is the point where a perpendicular is drawn from point A to the horizontal plane (second surface 2), and ∠ACE is the effective gradient difference of the first route AC. Similarly, point F is the point where a perpendicular is drawn from point D to the horizontal plane (second surface 2), and ∠DBFE is the effective gradient difference of the second route DB.

[0041] Although only two candidate routes are shown in Figure 8, it is possible to search for many candidate routes by setting points A and D to arbitrary points. In the route guidance method of this embodiment, among these multiple candidate routes, the route with the lowest risk of damaging the underside of the vehicle 10 becomes the recommended route. In the example in Figure 8, the first route AC may be the recommended route. Furthermore, as shown in Figure 8, when the first surface 1 is considered as a single rectangular plane, it is desirable to include at least two routes that are diagonals of that plane in the candidate routes.

[0042] Figure 9 is an explanatory diagram showing an example of the display on the IVI 21 of a vehicle in the second embodiment. When the vehicle approaches a steep exit and it is difficult to proceed straight, a recommended route is displayed on the in-cabin monitor, for example, the IVI 21. Figure 9 shows an example of the display screen of the IVI 21 during low-speed driving, with the around-view screen 22 on the left half and the camera display screen 23 of the front camera on the right half. In the second embodiment, two arrows 25a and 25b indicating the recommended route AC are displayed on the around-view screen 22, for example, in red. Arrow 25a corresponds to the route from point M to point A in Figure 8, and arrow 25b corresponds to the route from point A to point C in Figure 8. Similarly, on the camera display screen 23 on the right side of the IVI 21, two arrows 26a and 26b indicating the recommended route AC are also displayed, for example, in red. Appropriate voice or text displays, such as warnings that proceeding straight may damage the underside of the vehicle, may also be provided.

[0043] In this second embodiment, the recommended route, which is an alternative to going straight, is displayed on the IVI21, informing the driver that going straight would damage the underside of the vehicle.

[0044] When determining the recommended route, not only the magnitude of the gradient difference but also other additional requirements may be considered. For example, if following the recommended route with the smallest gradient difference would result in a significant deviation from the subsequent planned route, another route may be recommended. In the example in Figure 8, if a right turn is planned after passing the exit, following the first route AC may result in a large steering angle when turning right, making it impossible to complete the turn. In this case, for example, if it is determined that the underside of the vehicle will not be damaged even if the second route DB is taken, it is preferable to recommend the second route DB as the recommended route.

[0045] Alternatively, if obstacles or large road surface irregularities are detected near the recommended route with the smallest gradient difference, there is a risk of damage to areas other than the lower front bumper tip 11, and the ride comfort will also deteriorate, so it is preferable to select another route as the recommended route. For example, the angle change rate due to road surface irregularities on the recommended route is calculated, and if this angle change rate is greater than a certain threshold, another route is recommended.

[0046] Furthermore, when traveling diagonally on a slope (i.e., the first surface 1), there is a possibility of contact with oncoming vehicles. Therefore, if a center line separating lanes exists on the first surface 1, it is desirable to determine the recommended route within the left lane. If there is a risk of damage to the underside of the vehicle on the route within the left lane, the driver may be encouraged to drive safely and then guided to a recommended route that includes the right lane. If there is no center line separating lanes, the left side may be identified from road data acquired by a camera or the like, and the same processing may be performed.

[0047] The second embodiment described above can be applied in exactly the same way to road surfaces with a convex gradient as shown in Figures 5 and 6.

[0048] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various modifications are possible. The present invention is not limited to route guidance within facilities such as parking lot exits, but can naturally also be applied to route guidance on general public roads. [Explanation of symbols]

[0049] 1,101... First side 2,102…Second side 10... Own vehicle 21…IVI 22... Around View Screen 23...Camera display screen

Claims

1. A method for guiding a vehicle's route when the route the vehicle is scheduled to travel includes a first surface on the near side and a second surface on the far side where the relative gradient changes, Obtain path gradient information relating to the relative gradient of the first surface with respect to the second surface. We request information about the vehicle's maximum passable gradient. Based on the above route gradient information and the above vehicle information, it is determined whether the underside of the vehicle will be damaged when moving from the first surface to the second surface. If damage is deemed likely, the driver will be notified in advance. How to provide route guidance for vehicles.

2. If it is determined that no damage will occur, the driver will be notified in advance. The method for guiding a vehicle's route according to claim 1.

3. Identify the location of the damage to the underside of your vehicle. The part that sustains this damage will also be reported. The method for guiding a vehicle's route according to claim 1.

4. Identify the importance of the damaged area, The driver will be notified in a manner that allows them to recognize the importance of this. The method for guiding a vehicle's route according to claim 3.

5. If damage is determined to be likely, a recommended route will be presented that bypasses the section from the first surface to the second surface. The method for guiding a vehicle's route according to claim 1.

6. The above maximum passable gradient is calculated based on the ground clearance of the lower surface of the vehicle's front bumper and the front overhang. The method for guiding a vehicle's route according to claim 1.

7. The above maximum passable gradient is calculated based on the ground clearance of the vehicle's undercarriage and its wheelbase. The method for guiding a vehicle's route according to claim 1.

8. Furthermore, the maximum passable gradient is corrected by the vehicle tilt angle due to suspension displacement, including changes over time. The method for guiding a vehicle's route according to claim 6 or 7.

9. As the above path gradient information, With the vehicle positioned on the first surface, the distance to the second surface is measured in two directions having different inclination angles vertically, and the relative gradient is calculated from these distances and their inclination angles. The method for guiding a vehicle's route according to claim 1.

10. A vehicle route guidance device for when the route the vehicle is scheduled to travel includes a first surface on the near side and a second surface on the far side where the gradient changes relatively, A path gradient information acquisition unit that obtains path gradient information relating to the relative gradient of the first surface with respect to the second surface, A vehicle information acquisition unit that obtains vehicle information regarding the maximum gradient that the vehicle can traverse, A risk determination unit that determines whether the lower part of the vehicle will be damaged when moving from the first surface to the second surface, based on the above-mentioned route gradient information and the above-mentioned vehicle information, An information display unit that notifies the driver in advance if damage is detected, Equipped with, A vehicle route guidance system.

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