Parking support system

Abstract

To provide a parking support system that can guide a vehicle so that a selectable parking space can be detected surely.SOLUTION: When there are a plurality of parked vehicles 2 parked along a road on which a vehicle 1 runs, a recommended route setting part sets, as a first reference position C1, a position which is away by a first distance D1 from a first parked vehicle 21 which is closest to the vehicle 1 of the plurality of parked vehicles 2 toward the vehicle 1 in a width direction of the vehicle 1, and sets, as a recommended route, a first recommended route R1 along a virtual line E1 extending in a running direction of the vehicle 1 from the first reference position C1. The recommend route setting part calculates a second distance D2 in the width direction of the vehicle 1 between a second parked vehicle 22 parked further away than the first parked vehicle 21 of the plurality of parked vehicles 2 and the virtual line E1, which maintains the first recommended route R1 when a difference ΔD between the second distance D2 and the first distance D1 is below a predetermined value, and changes the route to a second recommended route R2 which is different from the first recommended route R1 when the difference is larger than the predetermined value.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a parking assistance system for a vehicle. [Background technology]

[0002] In a parking assistance system that performs automatic parking control to park a vehicle in a target parking position, before starting automatic parking control, the driver performs driving operations himself and travels near the parking space to search for an available parking space that will serve as the target parking position. For example, Patent Document 1 discloses a parking assistance system that displays a guidance display based on the effective detection range of an ultrasonic sensor, superimposed on the view ahead of the vehicle, in order to properly detect obstacles that are the target of detection in parking assistance. In the system disclosed in Patent Document 1, a guidance display is displayed so that the vehicle can be guided so that obstacles present in front of the vehicle are within the effective detection range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6366881 Summary of the Invention [Problem to be solved by the invention]

[0004] Although multiple parked vehicles are parked in a line in a parking lot, there is a possibility that some vehicles are parked protruding from the other parked vehicles or parked farther back than the other parked vehicles. When multiple parked vehicles are not neatly aligned and the leading edges of the parked vehicles are uneven, if a system attempts to guide a vehicle along the parked vehicles in order to reliably detect available parking spaces, the vehicle will be guided along an irregular path, which may be annoying to the driver. Furthermore, frequent steering operations that cause the vehicle's direction of travel to change frequently may degrade the system's ability to detect obstacles. Therefore, there is a need for an improved method of guiding a vehicle so that available parking spaces can be reliably detected based on the conditions around the vehicle before automatic parking control begins.

[0005] The present invention has been made in consideration of the above-described circumstances, and its purpose is to guide the vehicle so that it can reliably detect available parking spaces when the driver drives to select a target parking position before the start of automatic parking control. [Means for solving the problem]

[0006] According to one aspect of the present invention, a parking assistance system is provided which includes a surrounding situation detection device configured to detect a surrounding situation of a vehicle, and an obstacle detection device configured to detect an obstacle close to the vehicle, and which is configured to perform automatic parking control to park the vehicle at a target parking position based on information about the surrounding situation of the vehicle detected by the surrounding situation detection device and the obstacle detected by the obstacle detection device. The parking assistance system further includes a demarcation line detection unit which detects demarcation lines that define parking spaces based on the surrounding situation of the vehicle, an available parking space detection unit which detects an available parking space that can be selected as the target parking position based on information about the surrounding situation of the vehicle and the obstacle, a recommended route setting unit which sets a recommended route for the vehicle to travel in order to search for the available parking space, and a display control unit which displays the recommended route set by the recommended route setting unit and the available parking space on a display device, and When a plurality of parked vehicles exist, the recommended route setting unit is configured to set a position that is a first distance away from a first parked vehicle that is closest to the vehicle among the plurality of parked vehicles as a first reference position, and to set a first recommended route as the recommended route along a virtual line that extends from the first reference position in a traveling direction of the vehicle, the recommended route setting unit is configured to calculate a second distance in the width direction of the vehicle between a second parked vehicle that is farther away than the first parked vehicle among the plurality of parked vehicles and the virtual line, and to maintain the first recommended route if a difference between the second distance and the first distance is equal to or less than a predetermined value, and to change the recommended route from the first recommended route to a second recommended route if the difference between the second distance and the first distance is greater than the predetermined value, and the second recommended route is set along a virtual line that extends in the traveling direction of the vehicle from a second reference position that is offset from the first reference position in the width direction of the vehicle. [Effects of the Invention]

[0007] According to the present invention, when the driver drives to select a target parking position before the start of automatic parking control, the vehicle can be guided so as to reliably detect a selectable parking space. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a parking assistance system for a vehicle according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view schematically showing a vehicle equipped with the parking assistance system according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of a first recommended route set based on parked vehicles. [Figure 4] FIG. 4 is a diagram illustrating an example of a case where the first recommended route is changed to the second recommended route. [Figure 5] FIG. 5 is a diagram illustrating another example of a case where the first recommended route is changed to the second recommended route. [Figure 6] FIG. 6 shows an example of a recommended route displayed superimposed on an overhead image displayed on a display device. [Figure 7] FIG. 7 is a flowchart showing the flow of the recommended route setting process in the first embodiment. [Figure 8] FIG. 8 is a flowchart showing the flow of processing when the recommended route is not displayed at an intersection. [Figure 9] FIG. 9 is a flowchart showing the flow of the recommended route setting process in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] -First embodiment- An automatic parking control system according to a first embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a block diagram showing a schematic configuration of the parking assistance system according to this embodiment. Fig. 2 is a plan view showing a vehicle equipped with the parking assistance system according to this embodiment. In Fig. 2, the front side of the vehicle is indicated by arrow F, the rear side of the vehicle is indicated by arrow B, the right side of the vehicle is indicated by arrow R, and the left side of the vehicle is indicated by arrow L.

[0010] As shown in FIG. 1, a vehicle 1 equipped with a parking assistance system 100 according to this embodiment includes a drive device 101, a brake device 102, a steering device 103, and a shift device 104.

[0011] The drive device 101 is configured to generate a drive force for driving the vehicle 1, and includes an engine controller (not shown) that controls the drive force in response to the amount of depression of an accelerator pedal (not shown) by the driver or in response to a control command from the control device 20, which will be described later. Note that the drive device 101 of the vehicle 1 can be, for example, an internal combustion engine, a motor, or the like.

[0012] The brake device 102 is a brake device that generates a braking force according to the amount of depression of the brake pedal (not shown) by the driver, and is equipped with a brake controller and a brake actuator for generating a braking force according to a braking command from the vehicle system or the control device 20.

[0013] The steering device 103 is configured as an electric power steering device (EPS) and is configured to give a steering angle to the steered wheels in response to a steering operation by the driver. The steering device 103 can also control the steering angle in response to a steering command from the control device 20 to change the traveling direction of the vehicle 1.

[0014] The shift device 104 is configured to be switchable among a D range for moving the vehicle 1 forward, an R range for moving the vehicle 1 backward, and a P range for fixing the gear of a transmission (not shown). The shift device 104 is equipped with an actuator (not shown), and in response to a control command from the control device 20, sets the shift device 104 to the D range when moving the vehicle 1 forward, sets the shift device 104 to the R range when moving the vehicle 1 backward, and sets the shift device 104 to the P range when temporarily stopping the vehicle 1 at a turning position or the like.

[0015] The parking assistance system 100 mounted on the vehicle 1 includes an obstacle detection device 10, an imaging device 11, a control device 20, etc. The parking assistance system 100 may further optionally include a steering angle sensor 13, a direction indicator 14, an operation input device 15, and a display device 30.

[0016] The obstacle detection device 10 is configured to detect objects present around the vehicle 1, i.e., obstacles to the vehicle 1, by transmitting and receiving laser light, ultrasonic waves, millimeter waves, etc., and to detect the distance between the obstacle and the vehicle 1. Information about the obstacles detected by the obstacle detection device 10 is input to the control device 20. Here, the obstacles include stationary objects present around the vehicle 1, such as parked vehicles, side walls, and pillars. Note that moving objects, such as other vehicles, motorcycles, bicycles, and pedestrians present behind or in front of the vehicle 1, may also be detected as obstacles.

[0017] In this embodiment, the obstacle detection device 10 is configured to detect obstacles close to the vehicle 1. The obstacle detection device 10 has, for example, a rear sonar sensor 10a that detects obstacles in the rear area of ​​the vehicle 1, a rear-side sonar sensor 10b that detects obstacles in the rear-side areas, a front sonar sensor 10c that detects obstacles in the front area, and a front-side sonar sensor 10d that detects obstacles in the front-side areas.

[0018] The sonar sensors can accurately measure three-dimensional information about obstacles approaching the vehicle 1. As shown in FIG. 2, the rear sonar sensor 10a has, for example, four sonar sensors arranged spaced apart in the rear portion 100a of the vehicle 1, and the front sonar sensor 10b has, for example, four sonar sensors arranged spaced apart in the front portion 100b of the vehicle 1. The rear side sonar sensors 10b are arranged one on each side of the rear portion 100a of the vehicle 1, and the front side sonar sensors 10d are arranged one on each side of the front portion 100b of the vehicle 1. Note that the number and arrangement of the sonar sensors are not limited to those shown in FIG. 2.

[0019] The imaging device (surrounding condition detection device) 11 is configured to capture images of the area surrounding the vehicle 1, including obstacles present around the vehicle 1, and detect the surrounding conditions of the vehicle 1. In this embodiment, the imaging device 11 has, for example, a rear imaging unit 11a arranged in a rear portion 100a of the vehicle 1 and capable of capturing images of the rear area, a front imaging unit 11b arranged in a front portion 100b of the vehicle 1 and capable of capturing images of the front area, a left side imaging unit 11c arranged in a left side mirror of the vehicle 1 and capable of capturing images of the left side area, and a right side imaging unit 11d arranged in a right side mirror of the vehicle 1 and capable of capturing images of the right side area. The imaging device 11 is configured to be able to capture images of a 360-degree area around the vehicle 1 using these imaging units 11a to 11d.

[0020] The imaging units 11a to 11d each have a digital camera with an imaging element such as a CCD or CMOS, and are configured to output information about the area around the vehicle 1 as still images and / or video. Image data of the area around the vehicle 1 captured by the imaging device 11 is input to the control device 20. The image data captured by the imaging device 11 can be used to form an around-view image of the vehicle 1 as if looking down from directly above. The imaging device 11 can also be configured as a single omnidirectional camera.

[0021] Signals from the steering angle sensor 13 and the direction indicator 14 are input to the control device 20 .

[0022] The operation input device 15 is configured to accept various operation inputs to the vehicle 1 from a user, for example, the driver. The operation input device 15 includes an automatic parking control switch that is operated by the driver to switch automatic parking control on and off. The display device 30 is configured, for example, as a liquid crystal display, and is configured to display images on the display screen in response to commands from the control device 20. The operation input device 15 may be configured, for example, as a touch panel integrated with the display screen of the display device 30. Note that, for example, a display monitor of a navigation system (not shown) can also be used as the display device 30.

[0023] The control device 20 is implemented as a computer (ECU) that includes a CPU (Central Processing Unit) that performs calculations, a RAM (Random Access Memory) that serves as the CPU's working area and a temporary storage area for calculation results, a ROM (Read Only Memory) that stores operating programs for executing automatic parking control, various control constants, maps, etc., an input interface, an output interface, etc.

[0024] The control device 20 is configured to execute the functions of an obstacle recognition unit 20a, a route calculation unit 20b, a parking control unit 20c, a partition line detection unit 20d, a parking space detection unit 20e, a driving operation detection unit 20f, a recommended route setting unit 20g, and a display control unit 20h by executing an operating program stored in the ROM, and to control the overall operation of the parking assistance system 100.

[0025] The parking assistance system 100 in this embodiment is configured to assist the driver in driving the vehicle 1 and perform automatic parking control to park the vehicle 1 at a target parking position, based on the surrounding conditions of the vehicle 1 detected by the imaging device 11 and information on obstacles close to the vehicle 1 detected by the obstacle detection device 10. First, the flow of operation of the automatic parking control will be described.

[0026] (1) System startup When the driver operates the automatic parking control switch of the operation input device 15, the control device 20 activates the parking assistance system 100. This turns on the automatic parking control.

[0027] (2) Driving in a parking lot In order to search for an available parking space, the driver performs a driving operation to drive the vehicle in the parking lot at a low speed (for example, about 10 km / h).

[0028] (3) Search for available parking spaces The parking space detection unit 20e of the control device 20 searches for a space where the vehicle 1 can be parked based on information about obstacles present around the vehicle 1 detected by the obstacle detection device 10 and image data of the area around the vehicle 1 acquired by the imaging device 11.

[0029] (4) Parking space availability display The route calculation unit 20b of the control device 20 calculates a route from the current position of the vehicle 1 to the searched section. The control device 20 determines whether there is a possible route from the current position of the vehicle 1 to the searched section, and displays the section with a possible route on the display device 30 as a parking space.

[0030] (5) Start of automatic parking control When the available parking space where the driver wants to park is displayed on the display device 30, the driver depresses the brake pedal to stop the vehicle 1 and selects the available parking space displayed on the display device 30. This starts automatic parking control with the selected available parking space as the target parking position.

[0031] (6) Automatic parking control execution The parking control unit 20c of the control device 20 controls the drive device 101, the brake device 102, the steering device 103, and the shift device 104, and automatically drives the vehicle 1 along the parking path generated by the path calculation unit 20b to move it to the target parking position.

[0032] (7) Automatic parking control completed When the control device 20 recognizes that the current position of the vehicle 1 has reached the target parking position, it sets the shift device 104 to the P range and ends the automatic parking control.

[0033] Of the operations (1) to (7) described above, during the period (1) to (5) until the automatic parking control starts, the driver must manually drive the vehicle and drive near the parking space in order to search for a parking space that will be the target parking position for the automatic parking control.

[0034] Here, effective detection ranges are defined for the obstacle detection device 10, which detects obstacles close to the vehicle 1, and the imaging device 11, which detects the surrounding conditions of the vehicle 1, both of which are provided in the parking assistance system 100. For example, the detectable range of the sonar sensor constituting the obstacle detection device 10 is approximately 0.3 m to approximately 3.5 m, and the effective detection range is approximately 0.5 m to approximately 2.5 m. When there are multiple parked vehicles along the road ahead of the vehicle 1, the imaging device 11 can detect approximately three parked vehicles.

[0035] The obstacle detection device 10 and the imaging device 11 can accurately detect a detection target within their effective detection ranges, but outside the effective detection ranges, the detection accuracy of the detection target may decrease or the detection target may not be detected at all. Furthermore, the detection accuracy tends to decrease for detection targets that exist at an angle to the detection direction of the obstacle detection device 10 and the imaging device 11.

[0036] If the obstacle detection device 10 cannot accurately detect the detection target, even if a parking space exists, the system cannot recognize the space as a parking space. A space that is not recognized as a parking space cannot be selected as a target parking position, and therefore automatic parking control for parking in that space cannot be executed, reducing the convenience of the automatic parking control.

[0037] To reliably detect available parking spaces, it is desirable to drive as close as possible to the parking space, taking into consideration the effective detection ranges of the obstacle detection device 10 and the imaging device 11. However, if the vehicle gets too close to the parking space, there is a possibility of contact with a parked vehicle. Therefore, if there are multiple parked vehicles along the road on which the vehicle 1 is traveling, the vehicle 1 is prompted to drive alongside the parked vehicles, thereby making it possible to include the parking space within the effective detection ranges of the obstacle detection device 10 and the imaging device 11 while avoiding contact with the parked vehicles.

[0038] However, for example, if multiple parked vehicles are not lined up neatly and the leading edges of the parked vehicles are scattered, setting a recommended route along the scattered parked vehicles will result in the vehicle being guided along an irregular recommended route, which may be annoying to the driver.Furthermore, frequent steering operations that cause the vehicle's direction of travel to change frequently may result in parked vehicles being positioned at an angle to the detection direction of the obstacle detection device 10, which may degrade the system's ability to detect obstacles.

[0039] Therefore, parking assistance system 100 in this embodiment guides vehicle 1 so that it can reliably detect a selectable available parking space. Specifically, parking assistance system 100 is configured to present a recommended route for vehicle 1 to travel when a driver intending to park using automatic parking control is traveling near a parking space while searching for an available parking space. Parking assistance system 100 sets a travel route that is considered optimal for safely and reliably detecting an available parking space as a recommended route, and displays the recommended route to encourage vehicle 1 to travel along the recommended route.

[0040] A method for setting a recommended route in the control device 20 will be described in detail below with reference to Figures 3 to 5. Figures 3 to 5 show examples of recommended routes for searching for available parking spaces in a parking lot that includes multiple parking stalls in a traffic zone where vehicles keep to the left.

[0041] The obstacle recognition unit 20a of the control device 20 is configured to recognize obstacles, including parked vehicles, present around the vehicle 1 based on the surrounding conditions of the vehicle 1 detected by the imaging device 11 and information on obstacles close to the vehicle 1 detected by the obstacle detection device 10.

[0042] The lane line detection unit 20d of the control device 20 is configured to detect lane lines that define parking spaces based on the surrounding conditions of the vehicle 1 detected by the imaging device 11. The lane line detection unit 20d can detect white lines (lane lines) based on, for example, image data of the surroundings of the vehicle 1 acquired by the imaging device 11, and recognize an area demarcated by the white lines and having a size equivalent to a parking space as a parking space. The size of a standard parking space for double parking for passenger cars is a parking width of approximately 2.5 m to 3 m and a parking depth (depth) of approximately 5 m to 5.8 m. The control device 20 can also obtain the width of the roads (aisles) within the parking lot based on, for example, image data input from the imaging device 11 or information on road shapes acquired from a map information database (not shown).

[0043] The recommended route setting unit 20g sets a recommended route for the vehicle 1 to travel in order to search for an available parking space. The recommended route is set appropriately in accordance with the surrounding conditions of the vehicle 1 and obstacles present around the vehicle 1 so that an available parking space can be detected by the vehicle 1 traveling along the recommended route.

[0044] Methods for setting a recommended route include, for example, a method of setting the route based on the parking lot lines that define parking spaces, and a method of setting the route based on parked vehicles. For example, in a parking lot without parking lot lines or parking lots where the lines are not clearly drawn, it is desirable to set the recommended route based on the parked vehicles around vehicle 1. This embodiment is configured to set an appropriate recommended route based on the parked vehicles around vehicle 1. Specifically, when there are multiple parked vehicles, the recommended route setting unit 20g sets a recommended route that suppresses steering operations by the driver to smoothly guide vehicle 1, avoids contact between vehicle 1 and the parked vehicles, and can reliably detect available parking spaces.

[0045] The recommended route setting unit 20g basically sets a recommended route extending in the traveling direction of the vehicle 1, using as a reference a position that is a predetermined distance toward the vehicle 1 in the vehicle width direction from the multiple parked vehicles detected by the obstacle recognition unit 20a. Furthermore, the recommended route is offset in accordance with variations in the parking positions of the multiple parked vehicles. A specific method for setting a recommended route in the recommended route setting unit 20g will be described in detail below.

[0046] (A) Setting the first recommended route FIG. 3 shows an example in which a plurality of parked vehicles 2 are parked in parallel along the left side of road A on which vehicle 1 is traveling. In the example shown in FIG. 3, a parking section B is defined by the plurality of parked vehicles 2 parked in parallel. A parking space sandwiched between the parked vehicles 2 is indicated by a parking stall P. The recommended route setting unit 20g sets a recommended route R based on a first parked vehicle 21 that is closest to vehicle 1 among the plurality of parked vehicles 2. Hereinafter, the recommended route R set based on the first parked vehicle 21 may also be referred to as a first recommended route R1.

[0047] In the example shown in FIG. 3 , the recommended path setting unit 20g sets a position that is a first distance D1 away from the front end 2a of the first parked vehicle 21 toward the vehicle 1 (right side, R direction) in the width direction of the vehicle 1 as a first reference position C1, and sets a first recommended path R1 along an imaginary line E1 extending from the first reference position C1 in the traveling direction of the vehicle 1. Note that when the first parked vehicle 21 is parallel back-parked, the front end of the first parked vehicle 21 is set as the front end 2a, and when the first parked vehicle 21 is parallel forward-parked, the rear end of the first parked vehicle 21 is set as the front end 2a, and the first distance D1 is set. Furthermore, although not shown in the figure, when the first parked vehicle 21 is parallel parked, the first recommended path R1 is set so as to be the first distance D1 away from the side end of the first parked vehicle 21 facing the road A. In other words, the first recommended path R1 is set using the part of the first parked vehicle 21 that faces the road A (front end, rear end, or side end) as a reference.

[0048] The first distance D1 corresponds to the distance (first set distance F1) set between the first parked vehicle 21 and the recommended route R1 in the width direction of the vehicle 1, and is set to an appropriate distance so that multiple parked vehicles 2 can be stably detected, available parking spaces can be reliably detected, and contact with the parked vehicles 2 can be avoided. For example, the first distance D1 can be set to approximately 1.0 m. The recommended route setting unit 20g may also set the center Ro of the first recommended route R1 to be located to the left of the center Ao of the road A, where the first parked vehicle 21 to be detected is located.

[0049] 3, the first recommended route R1 is shown as a strip-shaped route that extends linearly forward, which is the current traveling direction of the vehicle 1. The width L of the recommended route R, which includes the first recommended route R1, is set to be slightly wider than the width of the vehicle 1. The width L of the recommended route R indicates that if the left and right ends of the vehicle 1 are within the width L of the recommended route R, that is, if the left end of the vehicle 1 does not extend beyond the left end of the recommended route R or if the right end of the vehicle 1 does not extend beyond the right end of the recommended route R, then parked vehicles 2 on the left side of the vehicle 1, including the first parked vehicle 21, can be included within the effective detection range of the obstacle detection device 10.

[0050] Generally, drivers tend to select a parking space located on the opposite side of the vehicle width from the driver's seat more frequently than on the side where the driver's seat is located as a target parking position. Therefore, Fig. 3 shows an example of setting a first recommended route R1 so that parking space B located on the left side (L direction), the opposite side from the driver's seat, can be reliably detected in a traffic section where drivers drive on the left. In a traffic section where drivers drive on the right, the first recommended route R1 can be set so that parking space B located on the right side, the opposite side from the driver's seat, can be reliably detected.

[0051] Next, the recommended route setting unit 20g calculates a second distance D2 in the width direction of the vehicle 1 between the virtual line E1 and a second parked vehicle 22, which is farther away than the first parked vehicle 21, among the multiple parked vehicles 2, based on the surrounding data of the vehicle 1 obtained from the obstacle detection device 10 and the imaging device 11. The recommended route setting unit 20g determines whether to maintain the first recommended route R1 based on the difference ΔD (=|D1-D2|) between the first distance D1 to the first parked vehicle 21 and the second distance D2 to the second parked vehicle 22.

[0052] If the difference ΔD between the first distance D1 to the first parked vehicle 21 and the second distance D2 to the second parked vehicle 22 is equal to or less than a predetermined value Da, i.e., if it is determined that the second parked vehicle 22 is generally aligned with the first parked vehicle 21, the recommended path setting unit 20g maintains the first recommended path R1 set based on the first parked vehicle 21, as shown in FIG. 3. Here, the predetermined value Da is set to an appropriate value that can avoid contact between the vehicle 1 and the parked vehicle 2 and ensure reliable detection of the parked vehicle 2. The predetermined value Da can be set to, for example, approximately 0.3 m. Therefore, if the second parked vehicle 22 is located approximately 0.7 m to 1.3 m from the virtual line E1, the first recommended path R1 is maintained without being updated.

[0053] (B) Update of the first recommended route (B-1) When the second parked vehicle 22 is far from the vehicle 1 If the difference ΔD between the first distance D1 of the first parked vehicle 21 and the second distance D2 of the second parked vehicle 22 is greater than a predetermined value Da and the second distance D2 is greater than the first distance D1, that is, if the second parked vehicle 22 is located farther from the road A than the first parked vehicle 21 by more than the predetermined value Da, the recommended route setting unit 20g maintains the first recommended route R1 without updating it.

[0054] The recommended route setting unit 20g further calculates a third distance D3 in the width direction of the vehicle 1 between the virtual line E1 and a parked vehicle that is farther away than the second parked vehicle 22. For example, if the third distance D3 in the width direction of the vehicle 1 between the virtual line E1 and a third parked vehicle 23 that is adjacent to the second parked vehicle 22 at a distance is approximately the same as the first distance D1 of the first parked vehicle 21, it is determined that the first parked vehicle 21 and the third parked vehicle 23 are generally aligned, and the first recommended route R1 is maintained without being updated, as shown in FIG. 3. On the other hand, if the third distance D3 of the third parked vehicle 23 is greater than the first distance D1 of the first parked vehicle 21, it is determined that there is variation in the parking positions of the multiple parked vehicles 2, and the first recommended route R1 is changed to a second recommended route R2, as shown in FIG. 4.

[0055] The imaging device 11 is capable of detecting approximately three parked vehicles parked side by side in front of the vehicle 1, but the recommended route setting unit 20g can change the recommended route R from the first recommended route R1 to the second recommended route R2 as shown in FIG. 4 when the vehicle 1 is traveling along the recommended route R and the obstacle detection device 10 and the imaging device 11 are able to accurately detect the parking position of the third parked vehicle 23.

[0056] In addition, in order to determine whether to set the second recommended route R2, the recommended route setting unit 20g may also calculate the distance in the vehicle width direction between the virtual line E1 and one or more parked vehicles that are adjacent to the third parked vehicle 23 at a distance. In other words, if the difference ΔD between the first distance D1 to the first parked vehicle 21 and the second distance D2 to the second parked vehicle 22 is greater than the predetermined value Da, and if the third distance D3 in the vehicle width direction between the virtual line E1 and each of the multiple distant parked vehicles that are adjacent to the first parked vehicle 21 at a distance, including the second parked vehicle 22, is greater than the first distance D1, the recommended route setting unit 20g changes from the first recommended route R1 to the second recommended route R2.

[0057] The recommended path setting unit 20g can, for example, set a second reference position C2 by offsetting the first reference position C1 set based on the first parked vehicle 21 toward the parked vehicle 2, and set a strip-shaped second recommended path R2 having a width L along an imaginary line E2 extending in the traveling direction of the vehicle 1. Here, the second reference position C2 is set at an appropriate position so that a plurality of parked vehicles 2 parked in a dispersed manner can be stably detected, a parking space can be reliably detected, and contact with the parked vehicles 2 can be avoided. A second set distance F2 between the second reference position C2 in the vehicle width direction and the leading edge 2a of the second parked vehicle 22 can be set to a value different from the first set distance F1 (=first distance D1) described above, and can be set to, for example, a value greater than the first distance D1 (e.g., approximately 1.3 m to approximately 1.5 m). The second set distance F2 may also be set to the same value as the first distance D1 described above (approximately 1.0 m).

[0058] (B-2) When the second parked vehicle 22 is approaching the vehicle 1 If the difference ΔD between the first distance D1 of the first parked vehicle 21 and the second distance D2 of the second parked vehicle 22 is greater than a predetermined value Da and the second distance D2 is smaller than the first distance D1, that is, if the second parked vehicle 22 is located closer to vehicle 1 than the first parked vehicle 21 by more than the predetermined value Da, the recommended route setting unit 20g changes from the first recommended route R1 to the second recommended route R2, as shown in FIG. 5, in order to avoid contact between vehicle 1 and parked vehicle 2.

[0059] 5 shows an example in which the first recommended route R1 is changed to the second recommended route R2 in accordance with the parking position of the fourth parked vehicle 24. When the vehicle 1 travels along the recommended route R and the obstacle detection device 10 and the imaging device 11 are able to accurately detect the parking position of the fourth parked vehicle 24, the recommended route setting unit 20g can change the recommended route R from the first recommended route R1 to the second recommended route R2, as shown in FIG.

[0060] The recommended path setting unit 20g can, for example, set a third reference position C3 by offsetting the first reference position C1 set based on the first parked vehicle 21 toward the vehicle 1, and set a second recommended path R2 along an imaginary line E3 extending in the traveling direction of the vehicle 1. Here, the third reference position C3 is set at an appropriate position so that multiple parked vehicles 2 can be stably detected, available parking spaces can be reliably detected, and contact with the parked vehicles 2 can be avoided. A third set distance F3 between the third reference position C3 in the vehicle width direction and the leading edge 2a of the fourth parked vehicle 24 can be set to a value different from the first set distance F1 (=first distance D1) described above, and can be set to, for example, a value greater than the first distance D1 (e.g., approximately 1.3 m to approximately 1.5 m). The third set distance F3 may also be set to the same value as the first distance D1 described above (approximately 1.0 m).

[0061] Furthermore, the third set distance F3 is set so that the center Ro of the second recommended route R2 coincides with the center Ao of the road A, or is closer to the fourth parked vehicle 24 that is the detection target than the center Ao of the road A. As a result, as shown in Fig. 5, the second recommended route R2 is set so that the center Ro is located in an area to the left of the center Ao of the road A. The recommended route setting unit 20g can acquire the road width W of the road A on which the vehicle 1 is traveling, for example, from image data input from the imaging device 11 or a map information database (not shown), and estimate the center Ao of the road A based on the road width W.

[0062] (C) Setting the connection route When changing from the first recommended route R1 to the second recommended route R2, the recommended route setting unit 20g sets a connecting route R3 that connects the first recommended route R1 and the second recommended route R2, as shown in Figures 4 and 5. The recommended route setting unit 20g sets the connecting route R3 so that the steering angle when the vehicle 1 travels from the first recommended route R1 along the second recommended route R2 falls within a predetermined range. The recommended route setting unit 20g can calculate the length and angle of the connecting route R3 so that the driver can move from the first recommended route R1 to the second recommended route R2 with a smooth steering operation within a steering angle range of -90 degrees to +90 degrees, for example.

[0063] As described above, the recommended route setting unit 20g basically sets the first recommended route R1 based on the first distance D1 in the vehicle width direction between the vehicle 1 and the first parked vehicle 21, and sets the second recommended route R2 according to variations in the parking positions of the multiple parked vehicles 2 as the vehicle 1 moves forward. In this embodiment, the first recommended route R1 or the second recommended route R2 can be adjusted to not be displayed, taking into consideration the surrounding conditions of the vehicle 1 or the driver's intentions. Adjustment of the recommended route R will be described below.

[0064] (D) Adjusting the recommended route based on the driver's intention When the second recommended route R2, which is offset according to the parking position of the parked vehicle 2, is set, if the driver does not perform a driving operation to travel along the second recommended route R2, an incorrect route may be set or a route that does not match the driver's intention may be displayed. Therefore, the recommended route setting unit 20g can be set so that the second recommended route R2 is not displayed if the second recommended route R2 is set and no driving operation is performed toward the second recommended route R2.

[0065] The driving operation detection unit 20f of the control device 20 is configured to detect a driving operation by the driver toward the driver's seat (one side) or the opposite side from the driver's seat (the other side). The driving operation detection unit 20f can determine whether or not a driving operation by the driver has been performed based on, for example, the steering angle detected by the steering angle sensor 13 or a signal from the turn signal 14 operated by the driver.

[0066] The recommended route setting unit 20g may change to the second recommended route R2 when the driving operation detection unit 20f determines that a driving operation has been performed, and when the driving operation causes the distance between the vehicle 1 and the parked vehicle 2 to be equal to or greater than a first predetermined distance and within a second predetermined distance. Here, the first predetermined distance may be, for example, approximately 1 meter, and the second predetermined distance may be, for example, approximately 1.5 meters. This allows the route to be changed to the second recommended route R2 when the vehicle 1 approaches the parked vehicle 2 due to a driving operation by the driver.

[0067] (E) Adjustment of recommended routes at intersections In a parking lot where multiple parking spaces B are located, there may be an intersection where multiple roads intersect. When vehicle 1 passes through the intersection, the system cannot determine which direction vehicle 1 should go in order to detect available parking spaces. Furthermore, if a route contrary to the driver's driving intention is set and presented as recommended route R, the driver may feel uncomfortable, or the presentation of an unintended route may cause the driver to neglect checking for safety around the vehicle.

[0068] Therefore, if there is an intersection in the parking lot, the recommended route setting unit 20g sets the recommended route R not to be displayed at the intersection. For example, as described below, the recommended route setting unit 20g can estimate whether or not an intersection exists in the traveling direction of the vehicle 1 based on the detection status of the demarcation lines that define the parking space B or the parked vehicle 2, and set the recommended route R not to be displayed at the intersection.

[0069] (E-1) Hiding recommended routes based on parked vehicle detection status If the obstacle detection device 10 and the imaging device 11 do not detect multiple adjacent parked vehicles 2 over a predetermined distance, and the demarcation line detection unit 20d does not detect any demarcation lines over a predetermined distance, the recommended route setting unit 20g determines that an intersection exists and can be set so as not to display the recommended route R at the intersection. Here, the predetermined distance can be set to, for example, a distance equivalent to two to three parked vehicles parked side by side in order to determine whether or not an intersection exists.

[0070] (E-2) Hiding recommended routes based on lane marking detection status When the demarcation lines of a plurality of consecutive parking stalls are no longer detected after the demarcation line detection unit 20d has detected them, the recommended route setting unit 20g can be set to determine that an intersection exists and not display the recommended route R. Here, the plurality of parking stalls can be, for example, parking stalls for two to three cars for parallel parking in order to determine whether or not an intersection exists.

[0071] Fig. 6 shows an example of the display of the recommended route R set by the recommended route setting unit 20g. As shown in Fig. 6, a 360-degree bird's-eye view image 31a of the area around the vehicle 1 is displayed on the display screen 31 of the display device 30. The bird's-eye view image 31a includes multiple parked vehicles 2 lined up in parallel on the left side of the vehicle 1 and demarcation lines C1 that demarcate the parking spaces located on the left and right sides of the vehicle 1.

[0072] The display control unit 20h of the control device 20 superimposes (overlaps) the recommended route R set by the recommended route setting unit 20g on the overhead image 31a in the traveling direction of the vehicle 1 indicated by the arrow T, i.e., forward. Also, on the overhead image 31a, a parking frame P indicating that the parking space is available is superimposed on the available parking space detected by the available parking space detection unit 20e. The parking frame P can be, for example, a frame-shaped image corresponding to a parking section B.

[0073] The recommended route R is displayed as a strip-shaped image having a width L, but it is preferable that the displayed image does not interfere with the driver's safety confirmation. For example, the recommended route R can be displayed as a transparent image that allows the overhead image 31a to be seen through, or as an image that shows only the outline of the recommended route R, so as not to reduce the visibility of the overhead image 31a.

[0074] The flow of the process for setting a recommended route for searching for an available parking space in the automatic parking control according to this embodiment will be described below with reference to the flowchart in Fig. 7. The process shown in Fig. 7 is an example of the process for setting a recommended route, and is periodically executed by the control device 20. The process shown in Fig. 7 starts when the driver operates the operation input device 15 and selects ON for the automatic parking control.

[0075] In step S101, the recommended route setting unit 20g sets a first recommended route R1 based on the first parked vehicle 21 recognized by the obstacle recognition unit 20a, according to the setting method (A) described above. The first recommended route R1 is set in the traveling direction of the vehicle 1 along a virtual line E1 extending from the first reference position C1, as shown in Fig. 3. The display control unit 20h displays the first recommended route R1 set by the recommended route setting unit 20g on the bird's-eye view image 31a on the display device 30 by superimposing it on the bird's-eye view image 31a.

[0076] When the automatic parking control is turned on, the display control unit 20h can display on the display device 30 the first recommended route R1 and a message urging the driver to align the vehicle body with the road on which the vehicle 1 is traveling. Note that instead of a message, the driver may be notified by voice or the like to align the vehicle body with the road.

[0077] In step S102, the recommended route setting unit 20g calculates a second distance D2 in the width direction of the vehicle 1 between the virtual line E1 and a second parked vehicle 22 that is farther away than the first parked vehicle 21, based on data obtained from the obstacle detection device 10 and the imaging device 11.

[0078] In step S103, the recommended route setting unit 20g determines whether the difference ΔD (=|D1-D2|) between the first distance D1 to the first parked vehicle 21 and the second distance D2 to the second parked vehicle 22 is greater than a predetermined value Da. If the difference ΔD is greater than the predetermined value Da, the process proceeds to step S104. On the other hand, if the difference ΔD is equal to or less than the predetermined value Da, the process determines that the second parked vehicle 22 is substantially aligned with the first parked vehicle 21, and the process proceeds to step S109, where the first recommended route R1 is maintained.

[0079] In step S104, the recommended route setting unit 20g determines whether the second distance D2 of the second parked vehicle 22 is greater than the first distance D1 of the first parked vehicle 21. If the second distance D2 is less than or equal to the first distance D1 and the second parked vehicle 22 is located closer to vehicle 1 and further towards road A than the first parked vehicle 21, the process proceeds to step S107 and sets a second recommended route R2. On the other hand, if the second distance D2 is greater than the first distance D1 and the second parked vehicle 22 is located further back from road A than the first parked vehicle 21, the process proceeds to step S105 without updating the first recommended route R1.

[0080] In step S105, the recommended route setting unit 20g calculates a third distance D3 in the width direction of the vehicle 1 between the virtual line E1 and a third parked vehicle 23 that is adjacent to the second parked vehicle 22 at a distance.

[0081] In step S106, it is determined whether the second distance D3 to the third parked vehicle 23 is greater than the first distance D1 to the first parked vehicle 21. If the third distance D3 is greater than the first distance D1, it is determined that there is variation in the parking positions of multiple parked vehicles 2 located far from the vehicle 1, including the second parked vehicle 22 and the third parked vehicle 23, and the process proceeds to step S107 to set a second recommended route R2. On the other hand, if the third distance D3 is equal to or less than the first distance D1, the process proceeds to step S108.

[0082] In step S108, the recommended route setting unit 20g determines whether the difference ΔD (=|D1-D3|) between the first distance D1 and the third distance D3 is greater than a predetermined value Da. If the difference ΔD is greater than the predetermined value Da and the third parked vehicle 23 is closer to the vehicle 1 and is on the road A side than the first parked vehicle 21, the process proceeds to step S107, where a second recommended route R2 is set. On the other hand, if the difference ΔD is equal to or less than the predetermined value Da, the process determines that the third parked vehicle 23 is substantially aligned with the first parked vehicle 21, and the process proceeds to step S109, where the first recommended route R1 is maintained.

[0083] In step S107, the second recommended route R2 is set according to the setting method (B-1) or (B-2) described above, depending on the variations in the parked vehicles 2. As shown in FIG. 4 or FIG. 5, the second recommended route R2 is set in the traveling direction of the vehicle 1 along the virtual line E2 extending from the second reference position C2 or the virtual line E3 extending from the third reference position C3. The display control unit 20h displays the second recommended route R2 set by the recommended route setting unit 20g on the display device 30, superimposed on the overhead image 31a.

[0084] When setting the second recommended route R2, the recommended route setting unit 20g also sets a connecting route R3 to smoothly connect the first recommended route R1 and the second recommended route R2 in accordance with the setting method (C) described above, and displays this route together with the first recommended route R1 and the second recommended route R2 on the display device 30.

[0085] In step S110, the driving operation detection unit 20f determines whether the driver has performed a driving operation to travel along the second recommended route R2, based on, for example, the steering angle detected by the steering angle sensor 13 or a signal from the turn signal 14 operated by the driver. Here, the driving operation detection unit 20f may determine whether the driver has performed a driving operation from the time the second recommended route R2 is displayed in step S107 until the vehicle 1 has traveled a predetermined distance.

[0086] If it is determined that the driver has performed a driving operation to travel along the second recommended route R2, the process proceeds to step S111, where the second recommended route R2 set in step S107 is maintained. As a result, the second recommended route R2 continues to be displayed on the display device 30. On the other hand, if the driver has not performed a driving operation to travel along the second recommended route R2, the process proceeds to step S112, where the second recommended route R2 set in step S107 is set not to be displayed. As a result, the second recommended route R2 that was displayed on the display device 30 is no longer displayed.

[0087] After the first recommended route R1 or the second recommended route R2 is displayed on the display device 30 in steps S109 and S111, or after it is determined in step S112 that the second recommended route R2 will not be displayed, when the driver selects a parking space displayed on the display device 30, automatic parking control begins and the processing shown in Figure 7 is terminated.

[0088] Next, the flow of processing for hiding the recommended route R at an intersection when the recommended route R (first recommended route R1 and / or second recommended route R2) has been set as described above and is displayed on the display device 30 will be described with reference to the flowchart of Fig. 8. The processing shown in Fig. 8 is periodically executed by the control device 20 in parallel with the recommended route setting processing shown in Fig. 7.

[0089] First, in step S151, the demarcation line detection unit 20d determines whether or not a demarcation line C1 (see FIG. 6) defining a parking space B can be detected around the vehicle 1, based on information about obstacles present around the vehicle 1 detected by the obstacle detection device 10 and image data of the area around the vehicle 1 acquired by the imaging device 11. If the demarcation line C1 can be detected, the process proceeds to step S152; if the demarcation line C1 cannot be detected, the process proceeds to step S154.

[0090] In step S152, the recommended route setting unit 20g determines whether the partition lines for multiple consecutive parking stalls, which had been detected by the partition line detection unit 20d, are no longer being detected. If it is determined that the partition lines for multiple parking stalls are no longer being detected, it determines that an intersection exists, and proceeds to step S153, where it sets the recommended route R not to be displayed. On the other hand, if the partition lines are still being detected, it proceeds to step S155, where it continues to display the recommended route R on the display device 30.

[0091] In step S154, the recommended route setting unit 20g determines whether or not multiple adjacent parked vehicles 2 have been detected over a predetermined distance by the obstacle detection device 10 and the imaging device 11. If multiple parked vehicles 2 have not been detected, it is determined that an intersection exists because neither a dividing line nor a parked vehicle 2 has been detected over the predetermined distance, and the process proceeds to step S153, where the recommended route R is set not to be displayed. On the other hand, if a parked vehicle 2 has been detected, the process proceeds to step S155, where the recommended route R continues to be displayed on the display device 30.

[0092] The parking assistance system 100 for the vehicle 1 according to the present embodiment described above can achieve the following advantageous effects.

[0093] (1) Parking assistance system 100 includes an imaging device 11 configured to detect the surrounding conditions of vehicle 1 and an obstacle detection device 10 configured to detect obstacles in the vicinity of vehicle 1, and is configured to perform automatic parking control to park vehicle 1 at a target parking position based on information about the surrounding conditions of vehicle 1 detected by imaging device 11 and the obstacles detected by obstacle detection device 10. Parking assistance system 100 includes a partition line detection unit 20d that detects partition lines C1 that define parking spaces B based on the surrounding conditions of vehicle 1, an available parking space detection unit 20e that detects an available parking space P that can be selected as a target parking position based on the surrounding conditions of vehicle 1 and the information about obstacles, a recommended route setting unit 20g that sets a recommended route R along which vehicle 1 travels to search for an available parking space P, and a display control unit 38 that displays the recommended route R and the available parking space P set by recommended route setting unit 20g on display device 30. When a plurality of parked vehicles 2 exist along the road on which the vehicle 1 is traveling, the recommended route setting unit 20g is configured to set, as a first reference position C1, a position that is a first distance D1 away from a first parked vehicle 21 that is closest to the vehicle 1 among the plurality of parked vehicles 2 toward the vehicle 1 in the width direction of the vehicle 1, and to set, as a recommended route R, a first recommended route R1 along an imaginary line E1 that extends from the first reference position C1 in the traveling direction of the vehicle 1. The recommended route setting unit 20g is configured to calculate a second distance D2 in the width direction of the vehicle 1 between a second parked vehicle 22 that is farther away than the first parked vehicle 21 among the plurality of parked vehicles 2 and the imaginary line E1, and to maintain the first recommended route R1 if a difference ΔD between the second distance D2 and the first distance D1 is equal to or smaller than a predetermined value Da, and to change the recommended route R from the first recommended route R1 to a second recommended route R2 if the difference ΔD between the second distance D2 and the first distance D1 is greater than the predetermined value Da. The second recommended route R2 is set along an imaginary line E2 extending in the traveling direction of the vehicle 1 from a second reference position C2, which is offset from the first reference position C1 in the width direction of the vehicle 1.

[0094] When multiple parked vehicles 2 are present, the system sets a first recommended route R1 at a first distance D1 (e.g., approximately 1 meter) from the first parked vehicle 21 and prompts the vehicle 1 to travel along the recommended route R, thereby enabling the system to reliably detect available parking spaces. Furthermore, the system can prevent the vehicle 1 from coming into contact with obstacles, such as parked vehicles 2, while searching for available parking spaces P. Setting the recommended route R based on the parked vehicle 2 allows the system to set the recommended route R even in situations where the demarcation lines C1 cannot be detected. However, unlike the demarcation lines C1, multiple parked vehicles 2 may be parked with their leading edges not aligned and in a scattered manner. The recommended route setting unit 20g is configured to maintain the first recommended route R1 set based on the first parked vehicle 21 when the difference in distance ΔD between the first parked vehicle 21 and the second parked vehicle 22 is equal to or less than a predetermined value Da. Therefore, when guiding the vehicle 1 along the recommended route R, the system can avoid contact with parked vehicles 2 while minimizing the driver's frequent steering operations, which may be bothersome to the driver. Furthermore, if the difference in distance ΔD between the first parked vehicle 21 and the second parked vehicle 22 is greater than a predetermined value Da, the system is configured to change from the first recommended route R1 to the second recommended route R2, thereby making it possible to reliably detect available parking spaces P without overlooking them while avoiding contact with the parked vehicle 2. As a result, it is possible to prevent the system from failing to recognize an available parking space even though it exists, or from erroneously recognizing a space that is impossible to park in due to the presence of an obstacle as an available parking space, thereby improving the convenience of automatic parking control. Furthermore, the driver only needs to perform driving operations to follow the recommended route R displayed on the display device 30, thereby reducing the burden on the driver of finding an available parking space before the automatic parking control begins.

[0095] (2) The recommended route setting unit 20g maintains the first recommended route R1 when the difference ΔD between the second distance D2 from the second parked vehicle 22 and the first distance D1 from the first parked vehicle 21 is greater than the predetermined value Da and the second distance D2 is greater than the first distance D1. If the second parked vehicle 22 is located further back from the road A than the first parked vehicle 21, the second parked vehicle 22 may be parked in an irregular manner, and there is no risk of contact between the second parked vehicle 22 and the vehicle 1 even if the recommended route R is not updated. Therefore, by maintaining the first recommended route R1, it is possible to prevent the recommended route R from being frequently updated, which would be annoying to the driver. It is also possible to avoid setting an undesirable recommended route R based on an irregularly parked vehicle.

[0096] (3) When the difference ΔD between the second distance D2 from the second parked vehicle 22 and the first distance D1 from the first parked vehicle 21 is greater than the predetermined value Da and the second distance D2 is greater than the first distance D1, and when a third distance D3 in the width direction of the vehicle 1 between each of multiple distant parked vehicles 23 located adjacent to the first parked vehicle 21, including the second parked vehicle 22, and the virtual line E1 is greater than the first distance D1, the recommended route setting unit 20g changes the recommended route R from the first recommended route R1 to the second recommended route R2. When multiple parked vehicles 2 located far from the first parked vehicle 21 are parked consecutively at a distance from the road A, for example, a situation may arise in which the parking space is shifted away from the vehicle 1's traveling direction. Therefore, by changing the recommended route R to the second recommended route R2, it becomes possible to reliably detect parked vehicles 2 and reliably detect available parking spaces P without overlooking them.

[0097] (4) If the driver does not perform a steering operation in a direction approaching the second recommended route R2 after the second recommended route R2 is set and displayed on the display device 30, the recommended route setting unit 20g sets the second recommended route R2 not to be displayed. If the second recommended route R2 is displayed to encourage the vehicle 1 to travel along the second recommended route R2, but no driving operation is performed to approach the second recommended route R2, there is a possibility that an incorrect route has been set, or that a route that does not conform to the driver's intention has been set. Therefore, by hiding the second recommended route R2, it is possible to avoid continuing to display an inappropriate recommended route R.

[0098] (5) The recommended route setting unit 20g is configured not to display the recommended route R if the imaging device 11 and the obstacle detection device 10 do not detect adjacent parked vehicles 2 within a predetermined distance, and the lane marking detection unit 20d does not detect the lane marking C1. Because the system cannot determine the direction to proceed at an intersection in the parking lot, hiding the recommended route R in areas determined to be intersections prevents the driver's driving operations at the intersection from being impeded. Furthermore, because there are no available parking spaces P at the intersection in the first place, not displaying the recommended route R allows the driver to recognize that no available parking spaces P have been detected.

[0099] (6) The recommended route setting unit 20g may be configured not to display the recommended route R when the demarcation lines C1 for multiple consecutive parking spaces are no longer detected after the demarcation line detection unit 20d had detected the demarcation lines C1.

[0100] (7) The recommended route setting unit 20g sets the center Ro of the second recommended route R2 to the center Ao of the road A on which the vehicle 1 is traveling or to the second parked vehicle 22 side of the center Ao of the road A. This makes it possible to set a limit on the offset of the second recommended route R2 in the width direction of the vehicle 1 relative to the first recommended route R1. If the second parked vehicle 22 is parked so that it protrudes from the first parked vehicle 21, the second recommended route R2 is set offset toward the center Ao of the road A relative to the first recommended route R1. In such a case, if the center Ro of the second recommended route R2 is set beyond the center Ao of the road A, for example, the second recommended route R2 is offset to the right (R direction) in FIG. 5, and the detection target area for available parking spaces P switches from the left side to the right side shown in FIG. 5, which causes the driver to feel uncomfortable. There is also a risk of contact between the vehicle 1 and an obstacle on the right side. Therefore, by setting an upper limit on the offset in the vehicle width direction when setting the second recommended route R2, the second recommended route R2 can be set appropriately.

[0101] (8) The recommended route setting unit 20g sets a connecting route R3 that connects the first recommended route R1 and the second recommended route R2. The connecting route R3 is set so that the steering angle when the vehicle 1 travels from the first recommended route R1 to the second recommended route R2 is within a predetermined range. When the vehicle 1 moves from the first recommended route R1 to the second recommended route R2, it can travel with a steering angle within the predetermined range, allowing the driver to follow the recommended route R smoothly and with a sense of security through reasonable steering operations.

[0102] (9) The recommended route setting unit 20g sets the recommended route R as a strip having a width L in the vehicle width direction and extending linearly in the traveling direction of the vehicle 1. When the automatic parking control is turned on, the display control unit 20h causes the display device to display the first recommended route R1 along with a message urging the driver to align the vehicle body with the road A on which the vehicle 1 is traveling. Because the first recommended route R1 is displayed to extend along the traveling direction of the vehicle 1, the first recommended route R1 can be properly displayed by first urging the driver to align the vehicle 1 with the road A.

[0103] -Second embodiment- A parking assistance system 100 for a vehicle 1 according to a second embodiment of the present invention will be described below. The basic configuration of the parking assistance system 100 according to the second embodiment is the same as that of the first embodiment described above. The following mainly describes the differences from the first embodiment.

[0104] In this embodiment, before the second recommended route R2 is displayed on the display device 30, the first recommended route is first set not to be displayed, and when the driver performs a steering operation in a direction approaching the second recommended route R2, the second recommended route R2 is displayed on the display device 30.

[0105] The flow of the process for setting a recommended route for searching for an available parking space in automatic parking control in this embodiment will be described using the flowchart in Fig. 9. In the flowchart in Fig. 9, the processes in steps S101 to S109 are the same as the processes in steps S101 to S109 in the flowchart in Fig. 7 described above, and therefore description thereof will be omitted.

[0106] If it is determined in step S106 that the third distance D3 is greater than the first distance D1, or if it is determined in step S108 that the difference ΔD (=|D1-D3|) between the first distance D1 and the third distance D3 is greater than the predetermined value Da, the process proceeds to step S121. In step S121, the recommended route setting unit 20g calculates a second recommended route R2 according to the setting method (B-1) or (B-2) described above depending on the variation of the parked vehicles 2, but does not display it on the display device 30. In addition, the recommended route setting unit 20g sets the display device 30 not to display the first recommended route R1 displayed in step S101.

[0107] In step S122, the driving operation detection unit 20f determines whether the driver has performed a driving operation that brings the vehicle closer to the second recommended route R2, for example, based on the steering angle detected by the steering angle sensor 13 or a signal from the turn signal 14 operated by the driver.

[0108] If it is determined that the driver has performed a driving operation to approach and travel along the second recommended route R2, the process proceeds to step S123, where the second recommended route R2 calculated in step S121 is displayed on the display device 30. As a result, the second recommended route R2 is displayed on the display device 30 superimposed on the overhead image 31a. On the other hand, if the driver has not performed a driving operation to approach and travel along the second recommended route R2, the display device 30 is set not to display the second recommended route R2. As a result, neither the first recommended route R1 nor the second recommended route R2 is displayed on the display device 30.

[0109] Thereafter, when the driver selects an available parking space displayed on the display device 30, automatic parking control starts, and the process shown in FIG. 9 ends.

[0110] In the second embodiment, the recommended route setting unit 20g sets the display of the first recommended route R1 to not display when the difference ΔD between the second distance D1 from the second parked vehicle 22 and the first distance D1 from the first parked vehicle 21 is greater than a predetermined value Da, the second distance D2 is greater than the first distance D1, and a third distance D3 in the width direction of the vehicle 1 between each of multiple distant parked vehicles located adjacent to the first parked vehicle, including the second parked vehicle 22, and the virtual line E1 is greater than the first distance D1. Here, when the driver performs a steering operation in a direction approaching the second recommended route R2, the recommended route R is changed from the first recommended route R1 to the second recommended route R2. When multiple parked vehicles are parked consecutively at a distance from the road A, for example, the parking spaces may be positioned away from the vehicle 1 in its traveling direction. Therefore, by not displaying the first recommended route R1, the driver can be made aware that the system is not targeting these parked vehicles for detection. If the driver performs a driving operation in a direction approaching the second recommended route R2, i.e., in a direction approaching parked vehicles 2 parked deep inside, the second recommended route R2 can be set to detect these parked vehicles in accordance with the driver's intentions.

[0111] -Variations- (1) In the above-described embodiment, the first distance D1 when setting the recommended route R is the distance in the vehicle width direction from the leading edge 2a of the parked vehicle 2 to the left and right ends of the recommended route R. However, this is not limited to this, and the recommended route setting unit 20g may set the first distance D1 as the distance in the vehicle width direction from the leading edge 2a of the parked vehicle 2 to the center Ro of the recommended route R. The same applies to the second set distance F2 and the third set distance F3.

[0112] (2) In the above-described embodiment, the recommended route setting unit 20g sets the recommended route R in the shape of a strip having a width L in the vehicle width direction and extending in the traveling direction of the vehicle 1. However, this is not limited to this, and the recommended route R may be set, for example, in the shape of a line along which the vehicle 1 travels.

[0113] (3) In the above-described embodiment, the display control unit 20h is configured to display the recommended route R superimposed on the bird's-eye view image 31a of the surroundings of the vehicle 1 on the display screen 31 of the display device 30. However, this is not limited to this, and the recommended route R may be displayed superimposed on an image of the area ahead or the area behind the vehicle 1. Alternatively, the display device 30 may be configured as a HUD (Head-Up Display) and the recommended route R may be displayed on the HUD.

[0114] (4) In the above-described embodiment, an example has been described in which the recommended route R is set so as to detect multiple parked vehicles 2 located to the left of the vehicle 1. This takes into consideration the fact that in traffic zones where drivers keep to the left, drivers frequently select parking spaces located on the left side of the vehicle width as target parking positions. However, this is not limited to this, and the recommended route R can also be set in a similar manner to the above-described embodiment when detecting multiple parked vehicles 2 located to the right of the vehicle 1. Furthermore, the above-described embodiment can also be applied to set the recommended route R when multiple parked vehicles 2 are parallel parked.

[0115] Although several embodiments of the present invention have been described above, it should be noted that the present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the present invention. [Explanation of symbols]

[0116] 1 vehicle 2 Parked vehicle, 21 1st parked vehicle, 22 2nd parked vehicle, 23 3rd parked vehicle 10 Obstacle detection device 11 Imaging device 13 Steering angle sensor 14 Turn signal 15 Operation input device 20 control device, 20a obstacle recognition unit, 20b route calculation unit, 20c parking control unit, 20d partition line detection unit, 20e available parking space detection unit, 20f driving operation detection unit, 20g recommended route setting unit, 20h display control unit 30 Display device 100 Parking Assist System A road, Ao road center Parking space B C1 Lot line D1 1st distance, D2 2nd distance, D3 3rd distance E1, E2, E3 virtual lines F1: First set distance, F2: Second set distance, F3: Third set distance R Recommended route, Ro Recommended route center R1: First recommended route, R2: Second recommended route

Claims

1. an ambient condition detection device configured to detect ambient conditions of a vehicle; an obstacle detection device configured to detect obstacles in proximity to the vehicle; Equipped with A parking assistance system configured to perform automatic parking control to park the vehicle at a target parking position based on information about the surrounding conditions of the vehicle detected by the surrounding conditions detection device and the obstacle detected by the obstacle detection device, a parking space detection unit that detects parking space demarcation lines based on the surrounding conditions of the vehicle; an available parking space detection unit that detects an available parking space that can be selected as the target parking position based on information about the surroundings of the vehicle and the obstacle; a recommended route setting unit that sets a recommended route along which the vehicle will travel in order to search for the available parking space; a display control unit that causes a display device to display the recommended route set by the recommended route setting unit and the available parking spaces; Equipped with If there are multiple parked vehicles along the road on which the vehicle is traveling, the recommended route setting unit is configured to set, as a first reference position, a position that is a first distance away from a first parked vehicle that is closest to the vehicle in a width direction of the vehicle, and to set, as the recommended route, a first recommended route along a virtual line that extends from the first reference position in a traveling direction of the vehicle; the recommended route setting unit is configured to calculate a second distance in a width direction of the vehicle between a second parked vehicle among the plurality of parked vehicles that is farther away than the first parked vehicle and the virtual line, and to maintain the first recommended route when a difference between the second distance and the first distance is equal to or less than a predetermined value; and when the difference between the second distance and the first distance is greater than the predetermined value, the recommended route is changed from the first recommended route to a second recommended route, and the second recommended route is set along a virtual line extending in the direction of travel of the vehicle from a second reference position obtained by offsetting the first reference position in the width direction of the vehicle.

2. 2. The parking assistance system according to claim 1, wherein the recommended route setting unit maintains the first recommended route when a difference between the second distance from the second parked vehicle and the first distance from the first parked vehicle is greater than the predetermined value and the second distance is greater than the first distance.

3. 3. The parking assistance system according to claim 2, wherein the recommended route setting unit changes the recommended route from the first recommended route to the second recommended route when a difference between the second distance from the second parked vehicle and the first distance from the first parked vehicle is greater than the predetermined value and the second distance is greater than the first distance, and when a third distance in the vehicle width direction between each of a plurality of distant parked vehicles located adjacent to the first parked vehicle, including the second parked vehicle, and the virtual line is greater than the first distance.

4. The recommended route setting unit a setting that the first recommended route is not displayed when a difference between the second distance from the second parked vehicle and the first distance from the first parked vehicle is greater than the predetermined value and the second distance is greater than the first distance, and when a third distance in a width direction of the vehicle between each of a plurality of distant parked vehicles present adjacent to the first parked vehicle at a distance, including the second parked vehicle, and the virtual line is greater than the first distance; 3. The parking assistance system according to claim 2, wherein when the driver performs a steering operation in a direction approaching the second recommended route, the recommended route is changed from the first recommended route to the second recommended route.

5. 4. The parking assistance system according to claim 3, wherein the recommended route setting unit sets the second recommended route not to be displayed if the driver does not perform a steering operation in a direction approaching the second recommended route after the second recommended route is set.

6. 2. The parking assistance system according to claim 1, wherein the recommended route setting unit is configured not to display the recommended route when the surrounding condition detection device and the obstacle detection device do not detect a plurality of adjacent parked vehicles within a predetermined distance, and the lane marking detection unit does not detect the lane marking.

7. 2. The parking assistance system according to claim 1, wherein the recommended route setting unit sets the recommended route not to be displayed when the partition lines of a plurality of consecutive parking spaces are no longer detected after the partition lines were detected by the partition line detection unit.

8. 2. The parking assistance system according to claim 1, wherein the recommended route setting unit sets a center of the second recommended route to a center of a road on which the vehicle is traveling or to a side of the road closer to the second parked vehicle than the center of the road.

9. 2. The parking assistance system according to claim 1, wherein the recommended route setting unit sets a connecting route that connects the first recommended route and the second recommended route, and the connecting route is set so that a steering angle when the vehicle travels from the first recommended route along the second recommended route falls within a predetermined range.

10. the recommended route setting unit sets the recommended route in a strip shape having a width in a vehicle width direction and extending linearly in a traveling direction of the vehicle; 2. The parking assistance system according to claim 1, wherein when the automatic parking control is turned on, the display control unit causes the display device to display, together with the first recommended route, a message urging the driver to align the vehicle body with a road on which the vehicle is traveling.

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