Parking assistance method and parking assistance device

Abstract

Provided is a parking assistance method that is executed by a controller and includes detecting parking location candidates in the surroundings of a vehicle (S1) and displaying, on a display device visible to an occupant, a parking assistance image showing the positions of the parking location candidates with respect to the position of the vehicle (S3). A computer displays, for each parking location candidate, a display of the parking difficulty in a case where the vehicle parks in the parking location candidate and a display showing the reason for the parking difficulty, such displays being displayed on the display device so as to be superimposed on the parking assistance image (S4).

Description

Parking assistance method and parking assistance device

[0001] The present invention relates to a parking assistance method and a parking assistance device.

[0002] The following Patent Document 1 describes a technology that scores the parking difficulty of a parking space and presents the parking difficulty to the driver in letters or numbers.

[0003] Japanese Patent Application Laid-Open No. 2023-71541

[0004] The technology described in Patent Document 1 presents the parking difficulty level of a parking space to the driver using letters and numbers. This has led to a problem in that the driver is unable to grasp the cause of the difficulty when parking into the parking space. The present invention aims to enable the driver to grasp the cause of the difficulty when parking a vehicle in a parking position candidate detected around the vehicle.

[0005] According to one aspect of the present invention, there is provided a parking assistance method executed by a controller that detects parking position candidates around a vehicle and displays a parking assistance image showing the positions of the parking position candidates relative to the vehicle position on a display device visible to an occupant. The computer displays, for each parking position candidate, an indication of the parking difficulty level when parking the vehicle at the parking position candidate and an indication of the cause of the parking difficulty, superimposed on the parking assistance image on the display device.

[0006] According to the present invention, it is possible to understand the causes of difficulties when parking a vehicle at a parking position candidate detected around the vehicle. The objects and advantages of the present invention are realized and attained by using the elements and combinations set forth in the appended claims. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the invention as claimed.

[0007] 1 is a diagram illustrating an example of a schematic configuration of a parking assistance device according to an embodiment; (a) and (b) are schematic diagrams illustrating an example of a first automatic parking function; (a) and (b) are schematic diagrams illustrating an example of a second automatic parking function; (a) and (b) are schematic diagrams of an example of a parking assistance image; (a) and (b) are schematic diagrams of an example of an overhead image; (a) and (b) are schematic diagrams of an example of a camera image; (a) and (b) are schematic diagrams of an example of an overhead image; and (a) and (b) are schematic diagrams of an example of a camera image. A flowchart of an example of a parking assistance method according to an embodiment.

[0008] (Configuration) FIG. 1 is a diagram showing an example of a schematic configuration of a parking assistance device according to an embodiment. A vehicle 1 is equipped with a parking assistance device 10 that assists in parking the vehicle 1 at a target parking position. The parking assistance device 10 executes parking assistance control, which is control that assists the vehicle 1 in traveling along a target parking path from the current position of the vehicle 1 to the target parking position. For example, the parking assistance control may be automatic driving control that controls the vehicle 1 to travel along the target parking path of the vehicle 1 to the target parking position. Automatic driving control that controls the vehicle 1 to travel along the target parking path of the vehicle 1 refers to control that automatically controls all or part of the vehicle's steering angle, driving force, and braking force to automatically travel all or part of the vehicle 1 along the target parking path. Furthermore, for example, the parking assistance control may be control that assists the driver of the vehicle 1 in driving by displaying the target parking path and the current position of the vehicle 1 on a display device visible to the driver of the vehicle 1.

[0009] The parking assistance device 10 includes an external sensor 11, a vehicle sensor 12, a human machine interface (HMI) 13, a controller 15, and an actuator (ACTR) 16. The external sensor 11 detects objects within a predetermined distance range from the vehicle 1. The external sensor 11 detects the environment surrounding the vehicle 1, such as the relative position of the vehicle 1 and an object present around the vehicle 1, the distance between the vehicle 1 and the object, and the direction in which the object is present. The external sensor 11 may include, for example, a camera that captures the environment surrounding the vehicle 1. For example, the external sensor 11 may include a front camera that captures an image in front of the vehicle 1, a rear camera that captures an image behind the vehicle 1, and side cameras that capture images on the right and left sides of the vehicle 1. The external sensor 11 may include a distance measuring device such as a laser range finder, radar, or LiDR (Light Detection and Ranging).

[0010] The vehicle sensor 12 detects various information (vehicle information) about the vehicle 1. The vehicle sensor 12 may include, for example, a vehicle speed sensor that detects the traveling speed of the vehicle 1, a wheel speed sensor that detects the rotational speed of each tire of the vehicle 1, a three-axis acceleration sensor (G sensor) that detects the acceleration (including deceleration) of the vehicle 1 in three axial directions, a steering angle sensor that detects the steering angle, a steering angle sensor that detects the steering angle of the steered wheels, a gyro sensor, and a yaw rate sensor. The HMI 13 is an interface device that exchanges information between the parking assistance device 10 and an occupant (e.g., a driver). For example, the HMI 13 may include a display device visible to the occupant as an interface that presents visual information to the occupant. The HMI 13 may also include a speaker or a buzzer as an interface that presents auditory information to the occupant. The HMI 13 may also include operation elements such as buttons, switches, levers, dials, and keyboards that accept operational inputs from the occupant, or an interface such as a touch panel.

[0011] The controller 15 is an electronic control unit that performs parking assistance control of the vehicle 1. The controller 15 includes a processor 17 and peripheral components such as a storage device 18. The processor 17 may be, for example, a CPU or an MPU. The storage device 18 may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The functions of the controller 15 described below are realized, for example, by the processor 17 executing a computer program stored in the storage device 18. The actuator 16 operates the steering device, drive device, and braking device of the vehicle 1 in response to control signals generated by the controller 15 to generate vehicle behavior of the vehicle 1, thereby automatically driving the vehicle 1. The actuator 16 includes a steering actuator that operates the steering device, an accelerator opening actuator that operates the drive device, and a brake control actuator that operates the braking device.

[0012] Next, an overview of the parking assistance function of the parking assistance device 10 will be described. In this specification, a first automatic parking function and a second automatic parking function will be exemplified. For example, the parking assistance device 10 may have either or both of the first automatic parking function and the second automatic parking function. The first automatic parking function is a function that detects the relative position of a parking position candidate with respect to the vehicle 1 based on information on known targets around the parking position candidate, information on the parking position candidate, and position information on targets detected around the vehicle 1 by a sensor mounted on the vehicle 1, accepts an operation by the occupant to select the parking position candidate as a target parking position, and assists in parking the vehicle at the target parking position.

[0013] 2(a) and 2(b) are schematic diagrams illustrating an example of the first automatic parking function. When using the first automatic parking function, a parking position candidate 31 where the vehicle 1 should be parked is registered in advance in the parking assistance device 10. Specifically, targets present around the parking position candidate 31 are extracted and stored (registered) in the storage device 18. In the following description, the targets around the parking position candidate 31 stored in the storage device are referred to as "learned targets." In FIG. 2(a), the circle plots schematically represent learned targets.

[0014] For example, when the vehicle 1 is located near the parking position candidate 31 (for example, when a user previously parked the vehicle 1 in the same parking position as the parking position candidate 31 by manual driving), the parking assistance device 10 detects targets around the vehicle 1 using the external sensor 11 mounted on the vehicle 1 and stores the targets as learned targets. For example, targets may be detected from a surrounding image obtained by capturing an image of the surroundings of the vehicle 1 with a camera. For example, edge points where the brightness of adjacent pixels changes by a predetermined amount or more or points with characteristic shapes (feature points), such as edges or corners of targets such as road markings, road boundaries, and obstacles, on the captured image obtained by the camera, may be detected as targets.

[0015] The parking assistance device 10 stores parking assistance information, which is data related to the parking position candidate 31, in a storage device. For example, the parking assistance information may include data representing the feature amounts of the learned targets (hereinafter referred to as "feature amount data") and data representing the relative positional relationship between the parking position candidate 31 and the learned targets (hereinafter referred to as "relative position data"). As the relative position data, for example, the relative position of the learned targets with respect to the parking position candidate 31 may be stored. For example, the parking assistance device 10 can acquire the position of the learned targets detected when the vehicle 1 is parked in the same parking position as the parking position candidate 31 as the relative position of the learned targets with respect to the parking position candidate 31. The coordinates of the learned targets and the parking position candidate 31 in a coordinate system with a fixed point as the reference point (hereinafter referred to as "map coordinate system") may also be stored.

[0016] FIG. 2(b) shows a scene in which the vehicle 1 is parked using the first automatic parking function (hereinafter, this may be referred to as "when parking assistance is being performed"). When parking assistance is being performed, the external sensor 11 extracts targets around the vehicle 1. In the following description, targets around the vehicle 1 extracted when parking assistance is being performed are referred to as "surrounding targets." In FIG. 2(b), triangular plots schematically represent the surrounding targets. The parking assistance device 10 matches the learned targets with the surrounding targets to associate identical feature points, and calculates the relative position of the parking position candidate 31 with respect to the vehicle 1 based on the relative positional relationship between the surrounding targets detected when parking assistance is being performed and the vehicle 1, and the relative positional relationship between the learned targets associated with the surrounding targets and the parking position candidate 31.

[0017] For example, the parking assistance device 10 calculates the position of the parking position candidate 31 in a coordinate system (hereinafter referred to as the "vehicle coordinate system") based on the current position of the vehicle 1. When the relative position data includes coordinates of the learned targets and the parking position candidate 31 in the map coordinate system, the coordinates of the parking position candidate 31 in the map coordinate system may be converted to coordinates in the vehicle coordinate system based on the positions of the surrounding targets detected when parking assistance is performed and the positions of the learned targets in the map coordinate system. The parking assistance device 10 accepts an operation by the occupant to select the parking position candidate as the target parking position. For example, the occupant may select the target parking position by operating the HMI 13. The parking assistance device 10 calculates a target parking path 34 from the current position 33 of the vehicle 1 to the target parking position based on the relative position between the selected target parking position and the vehicle 1. The parking assistance device 10 performs parking assistance control for the vehicle 1 based on the calculated target parking path 34. For example, the controller 15 controls the actuator 16 so that the vehicle 1 travels along the target parking path 34 to the target parking position and stops at the target parking position. Also, for example, the controller 15 displays the target parking path 34 and the current position of the vehicle 1 on the display device of the HMI 13. In the following description, the display device of the HMI 13 may be simply referred to as the "display device."

[0018] FIG. 3 is a schematic diagram illustrating an example of the second automatic parking function. The second automatic parking function detects the relative positional relationship of a parking position candidate with respect to the current position of the vehicle 1 using the external sensor 11, accepts an operation by the occupant to select the parking position candidate as a target parking position, and assists in parking the vehicle at the target parking position based on the detected relative positional relationship. When parking control using the second automatic parking function is initiated, the parking assistance device 10 uses the external sensor 11 to detect an available vacant space 41 around the vehicle 1 and set it as a parking position candidate. For example, the parking assistance device 10 may detect the vacant space 41 based on the detection result of parking frame lines 40 indicating the parking space. Alternatively, for example, the parking assistance device 10 may detect parked vehicles as objects around the vehicle 1 and detect the space between the parked vehicles as the vacant space 41.

[0019] The parking assistance device 10 detects the relative position of a parking position candidate (vacant space) 41 with respect to the current position 33 of the vehicle 1 using an external sensor 11. The parking assistance device 10 accepts an operation by the occupant to select the parking position candidate 41 as a target parking position. The parking assistance device 10 calculates a target parking path 34 from the current position 33 of the vehicle 1 to the target parking position based on the relative position between the selected target parking position and the vehicle 1. The parking assistance device 10 performs parking assistance control of the vehicle 1 based on the calculated target parking path 34. For example, the controller 15 controls the actuator 16 so that the vehicle 1 travels along the target parking path 34 to the target parking position and stops at the target parking position.

[0020] For example, the second automatic parking function may be a function (FAP: Full Auto Parking) that automatically controls all of the steering angle, driving force, and braking force of the vehicle 1 so that the vehicle 1 travels along a target parking path 34 from the current position of the vehicle 1 to the target parking position, or a function (IPA: Intelligent Parking Assist) that the user operates the accelerator pedal and the brake pedal and the parking assistance device 10 automatically controls only the steering angle. Furthermore, for example, the controller 15 displays the target parking path 34 and the current position of the vehicle 1 on a display device.

[0021] While the parking assistance device 10 is performing parking assistance control, the controller 15 displays a parking assistance image on a display device, which indicates the positions of candidate parking positions relative to the position of the vehicle 1. FIG. 4 is a schematic diagram of an example of a parking assistance image. For example, the parking assistance image 50 may include either or both of an overhead image 60 and a camera image 80. The overhead image 60 is an image of the surroundings of the vehicle 1 viewed from a virtual viewpoint directly above the vehicle 1. The controller 15 may generate the overhead image 60 by performing viewpoint conversion on the images captured by the front camera, rear camera, and side camera of the external environment sensor 11 so that the surroundings of the vehicle 1 are viewed from a virtual viewpoint directly above the vehicle 1, and display the generated overhead image 60 on the display device. The controller 15 may also display camera images 80, which are images output from the front camera and rear camera of the external environment sensor 11, on the display device.

[0022] The controller 15 displays parking position candidate marks, which indicate the positions of parking position candidates detected around the vehicle 1, superimposed on the parking assistance image 50, thereby indicating the positions of the parking position candidates relative to the position of the vehicle 1. For example, the controller 15 may display a vehicle icon 61 indicating the position of the vehicle 1 and parking position candidate marks 62a, 62b, and 62c on the overhead image 60. In the example of Fig. 4, the parking position candidate mark 62a indicates the position of a parking position candidate with a relatively low parking difficulty level (sometimes referred to as "parking position candidate A" in the following description), the parking position candidate mark 62b indicates the position of a parking position candidate with a medium parking difficulty level (sometimes referred to as "parking position candidate B" in the following description), and the parking position candidate mark 62c indicates the position of a parking position candidate with a relatively high parking difficulty level (sometimes referred to as "parking position candidate C" in the following description). By displaying the vehicle icon 61 and the parking position candidate marks 62a to 62c superimposed on the overhead image 60, the occupant can grasp the positions of the parking position candidates A to C relative to the position of the vehicle 1. The controller 15 may also display, superimposed on the overhead image 60, obstacle icons 65b and 65c indicating the positions of obstacles detected by the external sensor 11 around the parking position candidate B and the parking position candidate C, respectively.

[0023] Furthermore, for example, the controller 15 may superimpose parking position candidate marks 82a, 82b, and 82c, which indicate the positions of parking position candidates A to C, on the camera image 80. Since the fields of view of the front camera and the rear camera are known to the occupant, by superimposing and displaying the parking position candidate marks 82a to 82c on the camera image 80 of the front camera and the rear camera, the occupant can grasp the positions of the parking position candidates A to C relative to the position of the vehicle 1.

[0024] The parking assistance image 50 may be a graphical user interface (GUI) that accepts an occupant's operation on operation elements, icons, marks, and figures drawn on the parking assistance image 50. For example, the controller 15 may accept an occupant's operation on operation elements, icons, marks, and figures drawn on the parking assistance image 50 via a touch panel provided on a display surface of a display device on which the parking assistance image 50 is displayed. For example, the controller 15 may accept an occupant's operation of selecting the parking position candidate marks 62a to 62c as an operation of selecting the parking position candidates A to C as the target parking position, respectively. For example, the controller 15 may accept an occupant's operation of directly touching the parking position candidate marks 62a to 62c as an operation of selecting the parking position candidate marks 62a to 62c. For example, the controller 15 may accept an operation to move a cursor mark on the parking assistance image 50 and select parking position candidate marks 62a to 62c using the cursor mark based on an operation on an operation element drawn on the parking assistance image 50 or a physical operation element provided on the HMI 13.

[0025] Furthermore, for example, the parking assist image 50 may include a parking start button 51 that receives an instruction to start parking assist control for the parking position candidate selected as the target parking position, and an end button 52 that receives an instruction to end parking assist control. When the occupant selects one of the parking position candidates A to C as the target parking position, the controller 15 may highlight only the parking position candidate mark of the selected parking position candidate, thereby notifying the occupant that one of the parking position candidates A to C is being selected as the target parking position. For example, the controller 15 may highlight the parking position candidate mark by displaying an area surrounded by the parking position candidate mark displayed as a frame line in a colored, transparent display.

[0026] For example, in the example of Fig. 4, the state in which parking position candidate A, which has a relatively low parking difficulty level, has been selected as the target parking position is indicated by hatching. Because parking position candidate A has been selected as the target parking position, only the parking position candidate mark 62a is highlighted among the parking position candidate marks 62a to 62c, and only the parking position candidate mark 82a is highlighted among the parking position candidate marks 82a to 82c. Also, for example, in the examples of Figs. 5(a), 5(b), and 6, the state in which parking position candidate B, which has a medium parking difficulty level, has been selected as the target parking position is indicated by hatching. Because parking position candidate B has been selected as the target parking position, only the parking position candidate mark 62b is highlighted among the parking position candidate marks 62a to 62c, and only the parking position candidate mark 82b is highlighted among the parking position candidate marks 82a to 82c.

[0027] In the examples of FIGS. 7(a), 7(b), and 8, for example, the state in which parking position candidate C, which has a relatively high parking difficulty level, is selected as the target parking position is indicated by hatching. Because parking position candidate C is selected as the target parking position, only the parking position candidate mark 62c is highlighted among the parking position candidate marks 62a-62c, and only the parking position candidate mark 82c is highlighted among the parking position candidate marks 82a-82c. The display format for highlighting the selected parking position candidate mark may be varied depending on the parking difficulty level of the parking position candidate selected as the target parking position. For example, the coloring (e.g., color or brightness) of the area surrounded by the frame of the parking position candidate mark may be varied depending on the parking difficulty level. As a result, the parking difficulty level for parking the vehicle 1 at each parking position candidate is superimposed on the parking assistance image 50. The controller 15 may also superimpose letters or numbers representing the parking difficulty level for parking the vehicle 1 at each parking position candidate on the parking assistance image 50.

[0028] See Fig. 4. On the parking assistance image 50, an icon indicating that the parking time or the number of turns required when parking at each of the parking position candidates A to C is long may be superimposed. In the example of Fig. 4, clock icons 63b and 63c indicating that the parking time or the number of turns required when parking at the parking position candidates B and C, respectively, are superimposed on or near the parking position candidate marks 62b and 62c.

[0029] Furthermore, an icon that receives an operation from the occupant to instruct that an explanation for each parking position candidate be displayed on the parking assistance image 50 may be superimposed on each parking position candidate on the parking assistance image 50. In the example of Fig. 4, an exclamation mark icon 64b that receives an operation from the occupant to instruct that an explanation for parking position candidate B be displayed is superimposed on or near the parking position candidate mark 62b in the bird's-eye view image 60, and an exclamation mark icon 64c that receives an operation from the occupant to instruct that an explanation for parking position candidate C be displayed is superimposed on or near the parking position candidate mark 62c. Furthermore, an exclamation mark icon 84b that receives an operation from the occupant to instruct that an explanation for parking position candidate B be displayed is superimposed on or near the parking position candidate mark 82b in the camera image 80, and an exclamation mark icon 84c that receives an operation from the occupant to instruct that an explanation for parking position candidate C be displayed is superimposed on or near the parking position candidate mark 82c.

[0030] FIG. 5A illustrates a scene in which the exclamation mark icon 64b is operated by the occupant. For example, the occupant may operate a physical operation element provided in the HMI 13 or an operation element depicted on the parking assistance image 50 to move the cursor 53 so that it points to the exclamation mark icon 64b, and then, while the cursor 53 is pointing to the exclamation mark icon 64b, operate a physical button or a GUI button to operate the exclamation mark icon 64b. The occupant may similarly operate the exclamation mark icon 84b shown in FIGS. 4 and 6. Upon receiving an operation on the exclamation mark icon 64b or 84b, the controller 15 displays a description 68b regarding the parking position candidate B on the overhead image 60, as shown in FIG. 5B. For example, the description 68b may be an explanation of the cause of the difficulty of parking the vehicle 1 at the parking position candidate B, such as "The aisle width is narrow, so the number of turns will be increased."

[0031] FIG. 7A illustrates a scene in which the occupant operates the exclamation mark icon 64c. For example, the occupant may operate the exclamation mark icon 64c by moving the cursor 53 so that it points to the exclamation mark icon 64c, and then, while the cursor 53 is pointing to the exclamation mark icon 64c, by operating a physical button or a GUI button. The occupant may operate the exclamation mark icon 84c shown in FIG. 4 or 8 in a similar manner. Upon receiving an operation on the exclamation mark icon 64c or 84c, the controller 15 displays a description 68c regarding the parking position candidate C on the overhead image 60, as shown in FIG. 7B. For example, the description 68c may be, for example, "There is an obstacle near the entrance. Please be careful of the right and left rear." This description explains the cause of the difficulty of parking the vehicle 1 at the parking position candidate C or explains precautions that the occupant should take note of when parking the vehicle 1 at the parking position candidate C.

[0032] 5(a) , the controller 15 displays, for each parking position candidate, an indication (hereinafter sometimes referred to as a "cause indication") indicating the cause of the parking difficulty when parking the vehicle 1 at each parking position candidate, superimposed on the parking assistance image 50. For example, in FIG. 5(a) , the controller 15 may display, as a cause indication indicating the cause of the parking difficulty when parking the vehicle 1 at parking position candidate B, an icon 66a indicating a narrow space for turning, superimposed on the overhead image 60. Also, in FIG. 5(a) , the controller 15 may display, as a cause indication indicating the cause of the parking difficulty when parking the vehicle 1 at parking position candidate B, an icon 67a indicating a large step around parking position candidate B (e.g., midway along the approach path to parking position candidate B), superimposed on the overhead image 60. The controller may display the icons 66a and 67a when parking position candidate B is selected as the target parking position, and may stop displaying the icons 66a and 67a when parking position candidate B is not selected as the target parking position.

[0033] 7(a) , for example, the controller 15 may superimpose an icon 69a indicating the presence of another object (e.g., an obstacle or another vehicle) near the parking position candidate on the overhead image 60 as a cause display indicating the cause of the parking difficulty when parking the vehicle 1 at the parking position candidate B. The controller may display the icon 69a when the parking position candidate C is selected as the target parking position, and may stop displaying the icon 69a when the parking position candidate B is not selected as the target parking position.

[0034] 5(a) , the controller 15 may highlight causes of parking difficulty when parking the vehicle 1 at the parking position candidate and superimpose the causes on the parking assistance image 50. For example, the controller 15 may superimpose a highlight, which is a figure or mark for highlighting the causes of parking difficulty, on the parking assistance image 50 as an indication of the causes of parking difficulty. For example, the controller 15 may superimpose a highlight 66b, which is a figure or mark for emphasizing that the space for turning is narrow, or a highlight 67b, which highlights that there is a large step around the parking position candidate B (for example, midway along the approach path to the parking position candidate B), on the overhead image 60.

[0035] 6 , the controller 15 may superimpose on the camera image 80 a highlight 86b, which is a graphic or mark for emphasizing that the space for maneuvering is narrow, or a highlight 87b for emphasizing that there is a large step around the parking position candidate B (for example, midway along the approach path to the parking position candidate B). The controller may display the highlights 66b, 67b, 86b, and 87b when the parking position candidate B is selected as the target parking position, and may stop displaying the highlights 66b, 67b, 86b, and 87b when the parking position candidate B is not selected as the target parking position.

[0036] 7( a). The controller 15 may superimpose a highlight 69b, which is a graphic or mark for emphasizing that the parking space is narrow due to the presence of another object (e.g., an obstacle or another vehicle) near the parking position candidate, on the overhead image 60. The controller 15 may also superimpose a highlight 89b, which is a graphic or mark for emphasizing that the parking space is narrow due to the presence of another object (e.g., an obstacle or another vehicle) near the parking position candidate, on the camera image 80. The controller 15 may display the highlights 69b, 89b when the parking position candidate C is selected as the target parking position, and may stop displaying the highlights 69b, 89b when the parking position candidate B is not selected as the target parking position.

[0037] 9( a). The controller 15 may determine whether there is a possibility of a decrease in parking accuracy (i.e., the proximity between the actual parking position of the vehicle 1 and the target parking position candidate) when the parking assistance device 10 parks the vehicle 1 at a parking position candidate under automatic driving control. For example, the controller 15 may determine that there is a possibility of a decrease in parking accuracy when the parking assistance device 10 parks the vehicle 1 at a parking position candidate under automatic driving control when the parking frame lines defining the parking position candidate are difficult to recognize (e.g., when the parking frame lines are faint or blurred) or when the parking position candidate or its surroundings are inclined. The controller 15 may superimpose an icon indicating a possibility of a decrease in parking accuracy when the parking assistance device 10 parks the vehicle 1 at the respective parking position candidate under automatic driving control on the overhead image 60 or the camera image 80 of the parking assistance image 50 for each parking position candidate.

[0038] 9(a), for example, parking position candidate marks 62d and 62e displayed superimposed on the bird's-eye view image 60 indicate the positions of parking position candidates D and E, respectively, where the parking difficulty level is medium or relatively high. In the example of FIG. 9(a), the controller 15 determines that the parking frame lines 71 that demarcate parking position candidate D are difficult to recognize, and therefore there is a possibility that the parking accuracy will decrease when parking the vehicle 1 at parking position candidate D under automatic driving control. For this reason, the controller 15 superimposes a question mark icon 70d, which indicates that there is a possibility that the parking accuracy at parking position candidate D will decrease, on or near the parking position candidate mark 62d.

[0039] Furthermore, the controller 15 determines that there is a possibility that the parking accuracy will be reduced when parking the vehicle 1 at the parking position candidate E under automatic driving control due to the presence of an incline in the parking position candidate E and its surroundings. Therefore, the controller 15 superimposes a question mark icon 70e, which indicates that there is a possibility that the parking accuracy at the parking position candidate E will be reduced, on or near the parking position candidate mark 62e.

[0040] Furthermore, the occupant may operate the question mark icon 70d or 70e by moving the cursor 53 so that it points to the question mark icon 70d or 70e, and operating a physical button or a GUI button while the cursor 53 is pointing to the question mark icon 70d or 70e. When an operation on the question mark icon 70d or 70e is accepted, the controller 15 may display on the overhead image 60, as shown in FIG. 9(b), an explanation regarding the cause of the possibility of reduced parking accuracy at the parking position candidates D and E, such as "The parking position may be shifted because the white lines are thin" or "The parking position may be shifted because there is an incline."

[0041] Further, for example, the controller 15 may superimpose a highlight, which is a figure or a mark for emphasizing the cause of the decrease in parking accuracy, on the parking assistance image 50. For example, in the case of Fig. 9(a) , a highlight 72 for highlighting a parking frame line 71, which is a possible cause of the decrease in parking accuracy at the parking position candidate D, may be superimposed on the overhead image 60.

[0042] 10 is a flowchart of an example of the parking assistance method of the embodiment. In step S1, the controller 15 detects parking position candidates existing around the vehicle 1. In step S2, the controller 15 generates a parking assistance image showing the positions of the parking position candidates relative to the position of the vehicle 1.

[0043] In step S3, the controller 15 displays a parking assistance image on the display device of the HMI 13. In step S4, the controller 15 displays, for each parking position candidate, an indication of the parking difficulty level when parking the vehicle 1 at the parking position candidate and an indication of the cause of the parking difficulty, superimposed on the parking assistance image on the display device of the HMI 13. Thereafter, the processing ends.

[0044] (Effects of the embodiment) (1) The controller 15 detects parking position candidates present around the vehicle 1, and displays a parking assistance image showing the positions of the parking position candidates relative to the position of the vehicle 1 on a display device visible to the occupant, and for each parking position candidate, displays an indication of the parking difficulty level when parking the vehicle 1 at the parking position candidate and an indication of the cause of the parking difficulty superimposed on the parking assistance image on the display device. This makes it easier to understand the parking difficulty level before starting parking when parking the vehicle at a parking position candidate detected around the vehicle 1, and makes it possible to understand the cause of the parking difficulty level of the parking position candidate when parking in a location with a high parking difficulty level.

[0045] (2) The controller 15 may receive an operation input from the occupant to select a parking position candidate displayed on the parking assistance image, and may highlight and superimpose on the parking assistance image the causes of parking difficulty when parking the vehicle 1 at the parking position candidate selected by the occupant. This improves the occupant's visibility of the causes of parking difficulty.

[0046] (3) The display showing the causes of parking difficulty may include, for example, an icon indicating that there is a narrow space for turning or that there is another object near the parking position candidate. This allows the driver to know before starting parking that there is not enough space for turning or that there is not enough clearance with another object near the parking position candidate.

[0047] (4) The parking assistance image may be a graphical user interface in which an icon that can be operated by the occupant is superimposed. The controller 15 may display an explanation about the parking position candidate when the operation on the icon is accepted. This allows the explanation about the parking position candidate to be displayed when the user needs it and not displayed when the user does not need it.

[0048] (5) An icon indicating that the parking time will be long or the number of turns will be large when parking at the parking position candidate displayed on the parking assistance image may be superimposed on the parking assistance image. This allows the driver to know before starting parking that the parking time will be long or the number of turns will be large.

[0049] (6) An icon indicating that parking accuracy may be reduced when parking at a parking position candidate due to automatic driving control may be superimposed on the parking assistance image. This allows the driver to know that parking accuracy may be reduced before the automatic parking control starts.

[0050] All examples and conditional terms described herein are intended for educational purposes to aid the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology, and should be construed without limitation to the specifically described examples and conditions above, and the configuration of examples herein for illustrating the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present invention.

[0051] 1...vehicle, 10...parking assistance device, 11...external sensor, 12...vehicle sensor, 13...human machine interface (HMI), 15...controller, 16...actuator, 17...processor, 18...storage device

Claims

1. A parking assistance method executed by a controller that detects parking position candidates around a vehicle and displays a parking assistance image showing the positions of the parking position candidates relative to the vehicle's position on a display device visible to an occupant, wherein the computer displays, for each parking position candidate, an indication of the parking difficulty level when parking the vehicle at the parking position candidate and an indication of the cause of the parking difficulty, superimposed on the parking assistance image on the display device.

2. The parking assistance method according to claim 1, characterized in that it receives an operational input from the occupant to select the parking position candidate displayed on the parking assistance image, and highlights the causes of parking difficulty when parking the vehicle at the parking position candidate selected by the occupant and displays the highlighted causes superimposed on the parking assistance image.

3. The parking assistance method according to claim 2, wherein the display showing the cause of the parking difficulty includes an icon indicating that the space for turning is narrow.

4. The parking assistance method according to claim 2 or 3, characterized in that the display indicating the cause of the parking difficulty includes an icon indicating the presence of another object near the parking position candidate.

5. The parking assistance method according to claim 1 or 2, characterized in that the parking assistance image is a graphical user interface in which an icon that can be operated by the occupant is superimposed, and when an operation on the icon is accepted, an explanation regarding the parking position candidate is displayed.

6. A parking assistance method as described in any one of claims 1 to 5, characterized in that an icon indicating that the parking time or the number of maneuvers required when parking at the parking position candidate displayed on the parking assistance image will be long is displayed superimposed on the parking assistance image.

7. A parking assistance method as described in any one of claims 1 to 6, characterized in that an icon indicating that parking accuracy may be reduced when parking at the parking position candidate due to automatic driving control is displayed superimposed on the parking assistance image.

8. A parking assistance device that detects parking position candidates around a vehicle and displays a parking assistance image showing the positions of the parking position candidates relative to the vehicle's position on a display device visible to an occupant, the parking assistance device comprising a controller that executes processing to display, for each parking position candidate, an indication of the parking difficulty level when parking the vehicle at the parking position candidate and an indication of the cause of the parking difficulty, superimposed on the parking assistance image on the display device.

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