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, determines the maximum gradient the vehicle can pass through, and then 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, it calculates a recommended route with a lower risk of damaging the underside and presents it to the driver. For example, a route that detours to the right and proceeds diagonally is displayed as a recommended route on the vehicle's IVI21 screen with arrows 25a, 25b, 26a, and 26b.

Description

Technical Field

[0001] The present 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 travel 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 and 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 and exit and the outside road connected to the entrance and exit. 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] The present 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, a recommended route is determined that minimizes the risk of damaging the underside of the vehicle when proceeding from the first surface to the second surface. Present this recommended route to the driver.

[0006] For example, when descending a steep slope, traveling diagonally results in a gentler actual incline than traveling in a straight line. This principle is used to determine and present recommended routes to the driver. [Effects of the Invention]

[0007] According to this invention, when a low-clearance vehicle is at risk of damaging its undercarriage at the entrance or exit of a parking lot with a slope, a recommended route with less risk is presented to the driver, allowing the driver to operate their vehicle more safely. [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 diagram illustrating the recommended route, which proceeds diagonally. [Figure 3] A flowchart showing the processing flow of one embodiment of the present invention. [Figure 4] An explanatory diagram showing an example of a vehicle's IVI (In-Vehicle Infotainment) display. [Figure 5] A diagram illustrating the maximum gradient a vehicle can traverse. [Figure 6] An explanatory diagram showing the case where the first surface and the second surface are convex. [Figure 7] An explanatory diagram illustrating the maximum passable gradient when the first and second surfaces are convex. [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 this 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, a route that proceeds diagonally from the first surface 1 to the second surface 2 is presented to the driver as a recommended route.

[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] Figure 3 is a flowchart showing the processing flow of a route guidance system in one embodiment. 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 example targets 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.

[0014] In step 2, route gradient information is obtained regarding the exit to be reached, specifically the relative gradient of the first surface 1 to the second surface 2 (in other words, the difference in gradient between the two, θ1), as shown in Figure 1. This route gradient information may be obtained, for example, from the map information of a car navigation system if the map information includes gradient information; or, as a so-called connected car, the information may be obtained from a cloud server via a wireless communication network; or, as will be described later, the vehicle 10 may perform gradient difference detection or measurement.

[0015] In step 3, vehicle information regarding the maximum passable gradient θ0 of the vehicle is obtained. The maximum passable gradient θ0, as will be explained in more detail later, is, in one example, 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. This basic information is stored in the memory of the vehicle 10, for example, based on the vehicle's design value data. When additional information such as the aging deterioration of the suspension, as will be explained later, is considered, this information is added to determine the maximum passable gradient.

[0016] Next, in step 4, if the host vehicle 10 travels straight from the first surface 1 to the second surface 2, it is determined whether the lower part of the vehicle (for example, the lower part of the front bumper tip 11) is damaged. Basically, this is based on a comparison of the gradient difference θ1 indicated by the route gradient information with the maximum passable gradient θ0 of the host vehicle 10. If it is determined that there is no damage, proceed to step 5, and guide the driver to pass by reducing the vehicle speed. For example, it may be notified to the driver by voice, or presented as a character display or an image display on the vehicle's IVI (In-Vehicle-Infotainment). Thereby, the driver can know in advance that straight travel is possible and can proceed with confidence.

[0017] In step 4, if it is determined that the lower part of the vehicle will be damaged when traveling straight, proceed to step 6, and extract a plurality of candidate routes for traveling obliquely. As candidate routes, as shown in FIG. 2 described later, at least the first route AC that detours to the right from the current position and travels obliquely from the first surface 1 to the second surface 2, and the second route DB that detours to the left from the current position and travels obliquely from the first surface 1 to the second surface 2 are included. In one embodiment, two of the first route AC and the second route DB are extracted as candidate routes.

[0018] Then, in the next step 7, the inclination angle ∠ACE of the first route AC and the inclination angle ∠DBF of the second route BD are compared. If the inclination angle ∠ACE of the first route AC is smaller, the first route is selected as the provisional recommended route (step 8), and if not, the second route BD is selected as the provisional recommended route (step 9). Next, in step 10, it is determined whether the lower part of the vehicle is damaged when traveling along the provisional recommended route selected in steps 8 and 9. Basically, this is based on a comparison of the inclination angle (∠ACE or ∠DBF) in the selected provisional recommended route with the maximum passable gradient θ0.

[0019] If it is determined in step 10 that the lower part of the vehicle is not damaged, proceed to step 11 and guide the driver using the provisional recommended route selected in steps 8 and 9 as the final recommended route. If it is determined in step 10 that the lower part of the vehicle is damaged, proceed to step 12 and guide the driver to turn back. In other words, present a detour route that bypasses the said exit and uses another exit as the recommended route.

[0020] Figure 2 is an explanatory diagram of a recommended route that proceeds diagonally. Figure 2 simplifies and explains the principle for determining the recommended route. It is assumed that the first surface 1 and the second surface 2 are each flat surfaces without irregularities, and that the second surface 2 is a horizontal plane and the first surface 1 is inclined at a certain gradient with respect to this horizontal plane which is the second surface 2. In the illustrated example, the first surface 1 has a trapezoidal shape. The route MN in the figure is an example where the host vehicle 10 proceeds straight on the first surface 1 which is a downhill slope. The point O is the point where a perpendicular line is dropped from the point M to the horizontal plane (second surface 2), and ∠MON corresponds to the gradient difference θ1 described above. If this ∠MON is larger than the maximum passable gradient θ0 of the host vehicle 10, there is a risk of damaging the lower part. Therefore, as candidate routes, a first route AC that proceeds diagonally on the second surface 2 by detouring from the current position to point A on the right side and a second route DB that proceeds diagonally on the second surface 2 by detouring from the current position to point D on the left side are obtained, for example, based on map information. The point E is the point where a perpendicular line is dropped from the point A to the horizontal plane (second surface 2), and ∠ACE becomes the substantial gradient difference of the first route AC. Similarly, the point F is the point where a perpendicular line is dropped from the point D to the horizontal plane (second surface 2), and ∠DBF becomes the substantial gradient difference of the second route DB.

[0021] Although only two candidate routes are shown in Figure 2, 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 such 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 2, the first route AC may be the recommended route. Furthermore, as shown in Figure 2, 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.

[0022] Figure 4 is an explanatory diagram showing an example of a display in the vehicle's IVI (In-Vehicle Information and Window) system. When the vehicle approaches a steep exit and it is difficult to proceed straight, a recommended route is displayed on the in-vehicle monitor, for example, the IVI 21. Figure 4 shows an example of the IVI 21 display screen during low-speed driving, with the left half having an around-view screen 22 and the right half having a camera display screen 23 of the front camera. The around-view screen 22 combines images from multiple cameras installed in the vehicle to display an image around the vehicle icon 24 representing the vehicle 10, as if the vehicle 10 were viewed from directly above. Two arrows 25a and 25b indicating the recommended route AC are displayed here, for example in red. Arrow 25a corresponds to the route from point M to point A in Figure 2, and arrow 25b corresponds to the route from point A to point C in Figure 2. Similarly, in the camera display screen 23 on the right side of the IVI 21, two arrows 26a and 26b indicating the recommended route AC are displayed, for example in red. Additionally, appropriate audio or text displays may be provided, such as warnings that driving straight may damage the underside of the vehicle.

[0023] 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 2, 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.

[0024] 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.

[0025] 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.

[0026] Next, with reference to Figure 5, the maximum passable gradient θ0 of the vehicle will be explained. As shown in Figure 5, 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".

[0027] 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".

[0028] 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.

[0029] 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)".

[0030] 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 6, the present invention can also be applied when the first surface 101 and the second surface 102 are convex. In a convex road as shown in Figure 6, 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 proceeds straight, and a recommended route, for example, a diagonal route, is guided. For example, similar to the embodiment described above, multiple candidate routes are found that include at least a first route that detours to the right from the current position and proceeds diagonally from the first surface 101 to the second surface 102, and a second route that detours to the left from the current position and proceeds diagonally from the first surface 101 to the second surface 102. Among these candidate routes, the route with a relatively low risk of damaging the underside of the vehicle 10 can be selected as the recommended route and presented to the driver. In the example in Figure 6, the second surface 102 is almost horizontal, and the first surface 101 has a steep slope.

[0031] For a convex road like the one in Figure 6, the maximum passable gradient θ0 is given by "tan(θ0 / 2)=H / (W / 2)=2H / W" as shown in Figure 7, where H is the ground clearance of the underside of the body 33 and W is the wheelbase.

[0032] 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".

[0033] 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 6. As shown by arrows A and B in Figure 6, the gradient difference can be calculated by measuring distances in two directions, A and B.

[0034] 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 be applied to route guidance on general public roads. In the above embodiment, the recommended route is presented as an image on the IVI21, but it can be presented by any other method such as voice, text display, etc., and a warning sound may be emitted if the driver attempts to go straight. Furthermore, if it is predicted that there is no recommended route with a low risk of damage to the underside of the vehicle once a certain parking lot is entered, the route to the destination may be set to avoid passing through that parking lot. [Explanation of symbols]

[0035] 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, a recommended route is determined that minimizes the risk of damaging the underside of the vehicle when proceeding from the first surface to the second surface. Present this recommended route to the driver. How to provide route guidance for vehicles.

2. If it is determined that there is a high risk of damaging the underside of the vehicle if the vehicle proceeds straight from the first surface to the second surface, The recommended route is one that proceeds diagonally from the first surface to the second surface. The method for guiding a vehicle's route according to claim 1.

3. Find a number of candidate paths that include at least one first path that detours to the right from the current position and proceeds diagonally from the first surface to the second surface, and one second path that detours to the left from the current position and proceeds diagonally from the first surface to the second surface. Among these candidate routes, the route with a relatively low risk of damaging the underside of the vehicle will be selected as the recommended route. The method for guiding a vehicle's route according to claim 2.

4. If no recommended route with a low risk of damaging the underside of the vehicle can be found for the route from the first surface to the second surface, a route that bypasses the section from the first surface to the second surface will be presented as the recommended route. The method for guiding a vehicle's route according to claim 1.

5. The maximum passable gradient mentioned above 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.

6. 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.

7. 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 5 or 6.

8. 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.

9. 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 recommended route search unit that, based on the above route gradient information and the above vehicle information, finds a recommended route that minimizes the risk of damaging the underside of the vehicle when moving from the first surface to the second surface, This information display unit presents the recommended route to the driver, A vehicle route guidance system comprising the following:

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