Parking assistance method and parking assistance device

Abstract

In this parking assistance method, when registering learned landmark data to a storage device, in a case where a limitation factor exists, the learned landmark data is not registered to the storage device (S1: N), and, if an environment factor which depends on an environment of own vehicle exists as the limitation factor, the environment factor is displayed on a display device (S5), whereas if a user factor which depends on a user exists as the limitation factor, the user factor is displayed on the display device (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 that, during automatic parking by a parking assistance system, an alarm is output when it is determined that a parking operation should be prohibited.

[0003] Japanese Patent Application Laid-Open No. 2021-095113

[0004] In a parking assist control in which a target parking position is registered in advance in the vehicle and parking at the registered target parking position is supported, if a situation occurs in which the target parking position cannot be registered, the user may not be able to determine the cause and may not be able to deal with the situation. The present invention aims to make it easy for the user to deal with a situation in which the target parking position cannot be registered in the vehicle when the target parking position cannot be registered.

[0005] A parking assistance method for assisting a host vehicle in parking a target parking position is provided. The parking assistance method includes: detecting targets present around a target parking position in advance and registering data representing a relative positional relationship between the detected targets and the target parking position as learned target data in a storage device; detecting positions of surrounding targets that are targets present around the host vehicle when moving the host vehicle to the target parking position after registering the learned target data in the storage device; calculating a relative positional relationship between the target parking position and a current position of the host vehicle based on the learned target data and the positions of the surrounding targets; calculating a travel trajectory from the current position of the host vehicle to the target parking position based on the calculated relative positional relationship; and assisting the host vehicle in parking the target parking position based on the travel trajectory. The parking assistance method does not register the learned target data in the storage device if a limiting factor exists when registering the learned target data in the storage device; and, if an environmental factor dependent on the environment of the host vehicle exists as a limiting factor, displays the environmental factor on a display device; and, if a user factor dependent on the user exists as a limiting factor, displays the user factor on the display device.

[0006] According to the present invention, when a target parking position where the vehicle is to be parked cannot be registered, it is easy for the user to deal with the situation where the target parking position cannot be registered. The objects and advantages of the present invention are realized and attained by using the elements and combinations recited in the 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 parking assistance control; (a) is a schematic diagram of an example of a registration guidance screen; (b) is a schematic diagram of an example of a first help screen; (c) is a schematic diagram of an example of a second help screen; (d) is a flowchart of a driving assistance method according to a first embodiment; (e) is a block diagram of an example of the functional configuration of the controller of FIG. 1; (f) is a schematic diagram of an example of a registration possibility determination screen; and (f) is a flowchart of a driving assistance method according to a second embodiment.

[0008] (First Embodiment) (Configuration) FIG. 1 is a diagram showing an example of a schematic configuration of a parking assistance device according to an embodiment. A host vehicle 1 includes a parking assistance device 10 that assists the host vehicle 1 in parking at a target parking position. The parking assistance device 10 assists the host vehicle 1 in traveling along a target parking path from the current position of the host vehicle 1 to the target parking position. For example, an automatic driving may be performed in which the host vehicle 1 is controlled to travel to the target parking position along the target parking path of the host vehicle 1. The automatic driving that controls the host vehicle 1 to travel to the target parking position along the target parking path of the host vehicle 1 means control of all or part of the steering angle, driving force, and braking force of the host vehicle 1 to automatically perform all or part of the traveling of the host vehicle 1 along the target parking path. Furthermore, parking of the host vehicle 1 may be assisted by displaying the target parking path and the current position of the host vehicle 1 on a display device that is visible to a user (e.g., a passenger such as a driver) in the host vehicle 1.

[0009] The positioning device 11 measures the current position of the vehicle 1. The positioning device 11 includes, for example, a Global Navigation System (GNSS) receiver. Map data is stored in a map database (map DB) 12. The map data stored in the map database 12 may be, for example, map data for navigation or high-precision map data suitable for autonomous driving. The human-machine interface (HMI) 13 is an interface device that exchanges information between the parking assistance device 10 and a user. For example, the HMI 13 may include a display device visible to the user as an interface that presents visual information to the user. The HMI 13 may also include a speaker or a buzzer as an interface that presents auditory information to the user. The HMI 13 may also include an interface (such as a touch panel, button, switch, lever, dial, or keyboard) that accepts operational input from the user.

[0010] The shift switch (shift SW) 14 is a switch used by the driver or the parking assistance device 10 to switch the shift position of the host vehicle 1. The external sensor 15 detects objects within a predetermined distance range from the host vehicle 1. The external sensor 15 detects the surrounding environment of the host vehicle 1, such as the relative position of the host vehicle 1 and an object present around the host vehicle 1, the distance between the host vehicle 1 and the object, and the direction in which the object is present. The external sensor 15 may include, for example, a camera that captures the surrounding environment of the host vehicle 1. The external sensor 15 may also include a distance measuring device such as a laser range finder, radar, LiDAR (Light Detection and Ranging), or sonar. The vehicle sensor 16 detects various information (vehicle information) about the host vehicle 1. For example, the vehicle sensor 16 may include a vehicle speed sensor that detects the traveling speed of the host vehicle 1, a three-axis acceleration sensor that detects the acceleration (including deceleration) of the host vehicle 1 in three axial directions, and sensors that detect the steering angle of the steering wheel and the steering angle of the steered wheels. The parking switch (parking SW) 17 is a switch for starting the parking assist control by the parking assist device 10 .

[0011] The controller 19 is an electronic control unit that performs parking assistance control of the host vehicle 1. The controller 19 includes a processor 19a and peripheral components such as a storage device 19b. The processor 19a may be, for example, a CPU or an MPU. The storage device 19b may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The functions of the controller 19 described below are realized, for example, by the processor 19a executing a computer program stored in the storage device 19b. The parking brake 20 generates frictional braking force on the wheels of the host vehicle 1 in accordance with a user's operation or a control signal from the controller 19. The steering actuator 21a controls the steering direction and steering amount of the steering mechanism of the host vehicle 1 in accordance with the control signal from the controller 19. The accelerator actuator 21b controls the accelerator opening of a drive device such as an engine or a drive motor in accordance with the control signal from the controller 19. The brake actuator 21c activates a braking device in accordance with the control signal from the controller 19.

[0012] Next, parking assist control by the controller 19 will be described. FIGS. 2( a) and 2(b) are schematic diagrams illustrating parking assist control. When using parking assist control, a target parking position 31 where the host vehicle 1 should be parked is registered in advance in the parking assist device 10. Specifically, targets present around the target parking position 31 are extracted and stored (registered) in advance in the storage device 19b. In the following description, the targets around the target parking position 31 stored in the storage device 19b are referred to as "learned targets." In FIG. 2( a), circles schematically represent learned targets. When registering the target parking position 31 in the parking assist device 10, the user performs an operation to instruct registration of the target parking position 31 (hereinafter, sometimes referred to as a "registration operation"). For example, the registration operation may be operating (pressing) the parking switch 17 when the shift position is in the parking range. The controller 19 may automatically start the registration process of the target parking position 31 when the shift position is changed to the parking range. The parking assistance device 10 may be switchable between an automatic start mode in which the process of registering the target parking position 31 is automatically started when the shift position is changed to the parking range, and a manual start mode in which the process of registering the target parking position 31 is started when the parking switch 17 is operated while the shift position is in the parking range.

[0013] For example, when a user manually parks the vehicle 1 at the target parking position 31, the controller 19 detects targets around the vehicle 1 using the external sensor 15 and stores the targets as learned targets. For example, targets may be detected from an ambient image obtained by capturing an image of the surroundings of the vehicle 1 with a camera. For example, targets may be detected as edge points or points (feature points) with characteristic shapes, such as edges or corners of targets such as road markings, road boundaries, and obstacles, in the captured image captured by the camera, where the brightness of adjacent pixels changes by a predetermined amount or more. The controller 19 stores learned target data related to the learned targets in the storage device 19b. For example, the learned target data may include data representing the feature amounts of the learned targets (hereinafter referred to as "feature amount data") and data on the relative positional relationship between the target parking position 31 and the learned targets (hereinafter referred to as "relative position data"). For example, the relative position data may store the relative position of the learned targets relative to the target parking position 31. For example, the controller 19 can acquire the position of the learned target detected when the vehicle 1 is parked at the target parking position 31 as the relative position of the learned target with respect to the target parking position 31. The coordinates of the learned target and the target parking position 31 in a coordinate system with a fixed point as the reference point (hereinafter referred to as the "map coordinate system") may be stored.

[0014] 2B is an explanatory diagram of an example of processing when parking assistance is performed. The controller 19 starts parking assistance control of the host vehicle 1 when a user performs an operation to instruct activation of parking assistance control of the host vehicle 1 (hereinafter, this may be referred to as an "activation operation"). For example, the activation operation may be an operation of the parking switch 17 by the user. Furthermore, the controller 19 may automatically start parking assistance control when the host vehicle 1 approaches a registered target parking position 31.

[0015] When parking assist control begins, the controller 19 extracts targets around the host vehicle 1 using the external sensor 15. In the following description, targets around the host vehicle 1 extracted when parking assist is performed are referred to as "surrounding targets." In FIG. 2(b), triangular plots represent surrounding targets. The controller 19 detects the target parking position 31 by matching the learned targets with the surrounding targets and associating identical feature points. The controller 19 calculates the relative position of the host vehicle 1 with respect to the target parking position 31 based on the relative positional relationship between the surrounding targets detected when parking assist is performed and the host vehicle 1, and the relative positional relationship between the learned targets associated with the surrounding targets and the target parking position 31.

[0016] For example, the controller 19 calculates the position of the target parking position 31 in a coordinate system (hereinafter referred to as the "vehicle coordinate system") based on the current position of the host vehicle 1. Note that if the coordinates of the learned targets and the target parking position 31 in the map coordinate system are stored in the storage device 19b, the coordinates of the target parking position 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 host vehicle 1's own position in the map coordinate system may be determined 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, and the relative position of the host vehicle 1 with respect to the target parking position 31 may be calculated from the difference between the coordinates of the host vehicle 1 and the coordinates of the target parking position 31 in the map coordinate system. The controller 19 calculates a target parking path 34 from the current position 33 of the host vehicle 1 to the target parking position 31 based on the relative position of the host vehicle 1 with respect to the target parking position 31. The controller 19 performs parking assistance control of the host vehicle 1 based on the calculated target parking path 34 .

[0017] When registering learned target data for the target parking position 31 where the host vehicle 1 should be parked in the storage device 19b, the controller 19 determines whether there are any limiting factors that prevent the learned target data from being registered in the storage device 19b. If no limiting factors exist, the controller 19 displays a registration guidance screen on the display device of the HMI 13 to prompt the user to register the target parking position 31. FIG. 3 is a schematic diagram of an example of the registration guidance screen. For example, the registration guidance screen 40a includes a captured image 41 generated by capturing an image of the surroundings of the host vehicle 1, an overhead image 42 generated by converting the captured image of the surroundings of the host vehicle 1, a message display area 43 in which a visual message or other notification is displayed, a registration button 44, and an end button 45. The message display area 43 of the registration guidance screen 40a may display a visual message or other notification informing the user that the target parking position can be registered. When the user operates the registration button 44 or the end button 45 displayed on the display device, a touch panel provided on the display device detects the operation.

[0018] When the registration button 44 is operated, the controller 19 registers in the storage device 19b the learned target data of the learned targets detected around the target parking position 31. When the end button 45 is operated, the controller 19 stops the registration process of the target parking position 31. The same applies when the end button 45 on the registration possibility determination screen 40d shown in FIG. 8 is operated. On the other hand, if there is a limiting factor that prevents the learned target data from being registered in the storage device 19b, the controller 19 determines whether the limiting factor is a user factor that depends on the user or an environmental factor that depends on the environment of the host vehicle 1.

[0019] If the reason for the restriction is a user factor, the controller 19 displays a first help screen on the display device of the HMI 13 to inform the user of the user factor. Fig. 4 is a schematic diagram of an example of the first help screen. For example, the first help screen 40b includes an overhead image 42, a user factor display area 46 that displays the user factor, and a back button 47. When the user operates the back button 47, a touch panel provided on the display device detects this operation, and the controller 19 stops displaying the first help screen 40b.

[0020] If the reason for the restriction is an environmental factor, the controller 19 displays a second help screen on the display device of the HMI 13 to inform the user of the environmental factor. Fig. 5 is a schematic diagram of an example of the second help screen. For example, the second help screen 40c includes an overhead image 42, an environmental factor display area 48 that displays the environmental factors, and a back button 47. When the user operates the back button 47, the controller 19 stops displaying the second help screen 40c.

[0021] (Operation) FIG. 6 is a flowchart of the driving assistance method of the first embodiment. In step S1, the controller 19 determines whether the target parking position 31 can be registered (i.e., determines whether there is a restrictive reason for not registering the target parking position 31). If the target parking position 31 can be registered (step S1: Y), the process proceeds to step S2. If the target parking position 31 cannot be registered (step S1: N), the process proceeds to step S3. In step S2, the controller 19 displays a registration guidance screen 40a on the display device. In step S3, the controller 19 determines whether the restrictive factor for not registering the target parking position 31 is a user factor. If the restrictive factor is a user factor (step S3: Y), the process proceeds to step S4. If the restrictive factor is an environmental factor (step S3: N), the process proceeds to step S5. In step S4, the controller 19 displays a first help screen 40b on the display device. In step S5, the controller 19 displays a second help screen 40c on the display device.

[0022] Second Embodiment FIG. 7 is a block diagram of an example of the functional configuration of the controller 19. When the parking assistance device 10 is set to the manual start mode, the HMI control unit 50 outputs a map generation command to the map generation unit 55 to store learned target data in the storage device 19b upon detecting that the parking switch 17 has been operated while the shift position is in the parking range. When the parking assistance device 10 is set to the automatic start mode, the HMI control unit 50 outputs a map generation command to the map generation unit 55 upon detecting that the shift position has been changed to the parking range. The image conversion unit 52 converts images captured by the camera into overhead images viewed from a virtual viewpoint directly above the vehicle 1. The image conversion unit 52 converts the captured images into overhead images at predetermined intervals and accumulates the converted overhead images along the travel route of the vehicle 1 to generate a surrounding image, which is an image of the area surrounding the vehicle 1.

[0023] The self-position calculation unit 53 calculates the current position of the vehicle 1 on a map coordinate system as its own position by odometry (e.g., dead reckoning) based on vehicle information output from the vehicle sensor 16. The target detection unit 54 detects targets from the surrounding image output from the image conversion unit 52. The target detection unit 54 may detect the positions of feature points of the targets and their image feature amounts as targets. The target detection unit 54 outputs the detected positions of the feature points and the image feature amounts as target data to the map generation unit 55 and the target parking position detection unit 57. In addition, the self-position acquired from the self-position calculation unit 53 is output to the map generation unit 55 and the target parking position detection unit 57 in synchronization with the detection of the targets.

[0024] When the map generation unit 55 receives a map generation command from the HMI control unit 50 (i.e., when the registration process for the target parking position 31 begins), it performs a process to determine whether or not to register the learned target data. In the registration determination process, the map generation unit 55 determines whether or not to register the learned target data in the storage device 19b (i.e., whether or not there is a limiting factor that prevents the learned target data from being registered in the storage device 19b). For example, the map generation unit 55 determines whether or not a user factor exists as a limiting factor. The user factor may be, for example, that at least one of the following conditions (A) to (E) is satisfied when the host vehicle 1 is parked at the target parking position 31 to register the learned target data in the storage device 19b: (A) The door mirrors were retracted. (B) The door was open. (C) Wheel spin was detected. (D) The vehicle speed of the host vehicle 1 was equal to or greater than a threshold value (e.g., 30 km / h). (E) The travel distance was insufficient.

[0025] Furthermore, for example, the map generation unit 55 determines whether or not there is an environmental factor as a limiting factor. The environmental factor may include, for example, at least one of the following when the captured image from which the learned target object is extracted is captured: the number of feature points around the target parking position 31 is less than a predetermined value; the lighting conditions around the target parking position 31 are less than a predetermined condition; or the clearance around the target parking position 31 is less than a predetermined distance. The lighting conditions around the target parking position 31 may be conditioned on the brightness of the surroundings being equal to or less than a predetermined value. The clearance may be, for example, the distance between the edge of the vehicle 1 and an obstacle or the distance between the edge of the parking space and an obstacle when the target parking position 31 is registered.

[0026] While the map generation unit 55 is performing the registration possibility determination process, the HMI control unit 50 displays a registration possibility determination screen on the display device of the HMI 13 to inform the user that the registration process of the target parking position 31 is in progress. FIG. 8 is a schematic diagram of an example of the registration possibility determination screen. For example, the registration possibility determination screen 40d includes a captured image 41, an overhead image 42, a message display area 43, a help button 49, and an end button 45. For example, the message display area 43 may display a notification such as a visual message urging the user to press the help button 49 to check instructions regarding the registration of the target parking position 31 (e.g., important points to note when registering the target parking position 31). When the user operates the help button 49, the HMI control unit 50 detects the operation of the help button 49 via a touch panel provided on the display device.

[0027] If the help button 49 is operated before the registration possibility determination process is completed, the HMI control unit 50 displays the first help screen 40b shown in Fig. 4 on the display device of the HMI 13. The HMI control unit 50 may display visual messages informing the user of the above user factors (A) to (E), such as "When a mirror is closed," "When a door is opened," "When the wheels are spinning," "When the speed is high," and "When the mileage is insufficient," in the user factor display area 46 of the first help screen 40b.

[0028] On the other hand, when the registration determination process is completed and the map generation unit 55 determines to register the learned target data in the storage device 19b, the HMI control unit 50 displays the registration guidance screen 40a shown in FIG. 3 on the display device of the HMI 13. When the registration button 44 is operated, the map generation unit 55 stores the learned target data as map data 56 in the storage device 19b. Note that generation of the learned target data may be performed in parallel with the registration determination process, or generation of the learned target data may be started after determining to register the learned target data in the storage device 19b. For example, the map generation unit 55 receives the target data and the host position of the host vehicle 1 on the map coordinate system synchronized with the target data from the target detection unit 54. The map generation unit 55 acquires position information of the target parking position 31 in the map coordinate system. For example, the host position calculated by the host position calculation unit 53 when the host vehicle 1 is located in the target parking position 31 may be acquired as the position information of the target parking position 31. The map generation unit 55 generates relative position data based on the positions of the feature points included in the target data, the position information of the host vehicle 1 synchronized therewith, and the position information of the target parking position 31. The map generation unit 55 acquires feature amount data from the target data output from the target detection unit 54. The map generation unit 55 generates learned target data including the relative position data and feature amount data.

[0029] Furthermore, when the registration possibility determination process is completed and the map generation unit 55 determines not to register the learned target data in the storage device 19b (i.e., when a limiting factor exists), the HMI control unit 50 continues to display the registration possibility determination screen 40d illustrated in Fig. 8. When the help button 49 is operated, the HMI control unit 50 determines whether the limiting factor is a user factor or an environmental factor. If the limiting factor is a user factor, the HMI control unit 50 displays the first help screen 40b illustrated in Fig. 4 on the display device of the HMI 13. If the limiting factor is an environmental factor, the HMI control unit 50 displays the second help screen 40c illustrated in Fig. 5 on the display device of the HMI 13. The HMI control unit 50 may display visual messages in the environmental factor display area 48 of the second help screen 40c to inform the user of each of the above environmental factors (insufficient number of feature points around the target parking position 31, inappropriate lighting conditions around the target parking position 31, insufficient clearance around the target parking position 31), such as "when there is no or little road pattern," "when there is a shadow on the road surface or the surroundings are dark," and "when an obstacle is detected in an extremely close position while moving."

[0030] Note that, when user factors and environmental factors exist simultaneously, the HMI control unit 50 may prioritize displaying either the user factors or the environmental factors. For example, when the help button 49 is operated, the HMI control unit 50 may prioritize displaying either the first help screen 40b or the second help screen 40c. While user factors are factors that a user can resolve relatively easily, environmental factors are often difficult for users to resolve. For this reason, when user factors and environmental factors exist simultaneously, the HMI control unit 50 may prioritize displaying the environmental factors over the user factors. Conversely, the HMI control unit 50 may prioritize displaying the user factors over the environmental factors. When user factors and environmental factors exist simultaneously, both the user factors and the environmental factors may be displayed.

[0031] When the user operates the back button 47 on the first help screen 40b or the second help screen 40c, the HMI control unit 50 determines whether the limiting factor has been resolved. If the limiting factor has been resolved, the HMI control unit 50 may display the registration guidance screen 40a on the display device of the HMI 13. If the limiting factor has not been resolved, the HMI control unit 50 may display the registration possibility determination screen 40d on the display device of the HMI 13. Furthermore, if the limiting factor has been resolved, the HMI control unit 50 may automatically display the registration guidance screen 40a without the user operating the back button 47.

[0032] Furthermore, even if the limiting factor is resolved when the user operates the back button 47, the HMI control unit 50 may display the registration guidance screen 40a on the condition that the operation of parking the vehicle 1 at the target parking position 31 is repeated after the map generation unit 55 determines not to register the learned target data in the storage device 19b. If the operation of parking the vehicle 1 at the target parking position 31 is not repeated after the map generation unit 55 determines not to register the learned target data in the storage device 19b, the HMI control unit 50 may display the registration possibility determination screen 40d on the display device of the HMI 13.

[0033] For example, if the learned target data cannot be registered in the storage device 19b due to a problem with the surrounding image of the vehicle 1 generated by the image conversion unit 52 (i.e., the image from which the learned target is extracted) caused by a limiting factor, the operation of parking the vehicle 1 at the target parking position 31 may be redone before the registration guidance screen 40a is displayed. For example, if the surrounding image is not suitable for extracting feature points, the operation of parking the vehicle 1 at the target parking position 31 may be redone before the registration guidance screen 40a is displayed. For example, if the surrounding image is captured with the door mirrors retracted, the doors open, or the vehicle speed is too high, or if the driving distance when capturing the surrounding image is insufficient, a problem occurs in the surrounding image generated by the image conversion unit 52, and therefore the operation of parking the vehicle 1 at the target parking position 31 must be redone. The same applies when the number of feature points present around the target parking position 31 is insufficient or the lighting conditions around the target parking position 31 are inappropriate.

[0034] On the other hand, even if there is no problem with the surrounding image of the host vehicle 1 generated by the image conversion unit 52, if the map generation unit 55 determines not to register the learned target data in the storage device 19b, the registration guidance screen 40a may be displayed if the limiting factor is resolved, without the need to redo the operation of parking the host vehicle 1 at the target parking position 31. For example, if the door mirrors are folded or the doors are opened after the host vehicle 1 is parked at the target parking position 31 in order to register the learned target data in the storage device 19b, the registration guidance screen 40a may be displayed if these user factors are resolved, without the need to redo the operation of parking the host vehicle 1 at the target parking position 31. Also, for example, if the obstacles around the target parking position 31 are removed and the environmental factor of insufficient clearance around the target parking position 31 is resolved after the map generation unit 55 determines not to register the learned target data in the storage device 19b, the registration guidance screen 40a may be displayed without the need to redo the operation of parking the host vehicle 1 at the target parking position 31.

[0035] 7 . When the HMI control unit 50 detects a user's operation to activate the parking assist control, it outputs a control start command to the parking assist control unit 51 to start parking assist control to the target parking position. When the parking assist control unit 51 receives the control start command from the HMI control unit 50, it determines whether the current position of the host vehicle 1 is near the registered target parking position 31. If the current position of the host vehicle 1 is near the registered target parking position 31, the parking assist control unit 51 executes parking assist control. The parking assist control unit 51 may automatically start parking assist control when the host vehicle 1 approaches the registered target parking position 31. When the parking assist control unit 51 starts the parking assist control, it outputs a parking position calculation command to the target parking position detection unit 57. When the parking position calculation command is received, the target parking position detection unit 57 receives the target data output from the target detection unit 54 as target data of surrounding targets, and, in synchronization with this, receives the host vehicle 1's own position in the map coordinate system.

[0036] The target parking position detection unit 57 detects the target parking position 31 by matching the learned targets with the surrounding targets and associating targets with the same feature points. That is, whether the target parking position 31 can be detected is determined based on whether the matching between the learned targets and the surrounding targets is successful. If the matching is successful (i.e., if the target parking position 31 is detected), the target parking position detection unit 57 calculates the relative position of the host vehicle 1 with respect to the target parking position 31 based on the relative positional relationship between the surrounding targets and the host vehicle 1 and the relative positional relationship between the learned targets associated with the surrounding targets and the target parking position 31. The target trajectory generation unit 59 calculates a target parking path from the current position of the host vehicle 1 on the vehicle coordinate system to the target parking position 31. The target trajectory generation unit 59 calculates a target vehicle speed profile, which is a target value of the vehicle speed of the host vehicle 1 on the target parking path. The steering control unit 60 controls the steering actuator 21a so that the host vehicle 1 travels along the target parking path. The vehicle speed control unit 61 controls the accelerator actuator 21b and the brake actuator 21c so that the vehicle speed of the host vehicle 1 changes in accordance with the target vehicle speed profile. When the host vehicle 1 reaches the target parking position 31 and the parking assist control is completed, the parking assist control unit 51 activates the parking brake 20 and switches the shift position to the parking range.

[0037] FIG. 9 is a flowchart of the driving assistance method of the second embodiment. When the registration process of the target parking position 31 is started, in step S10, the HMI control unit 50 displays the registration possibility determination screen 40d. In step S11, the HMI control unit 50 determines whether the registration possibility determination process by the map generation unit 55 has been completed. If the registration possibility determination process has been completed (step S11: Y), the process proceeds to step S14. If the registration possibility determination process has not been completed (step S11: N), the process proceeds to step S12. In step S12, the HMI control unit 50 determines whether the help button 49 has been operated. If the help button 49 has been operated (step S12: Y), the process proceeds to step S13. If the help button 49 has not been operated (step S12: N), the process returns to step S10. In step S13, the HMI control unit 50 displays the first help screen 40b. Thereafter, the process returns to step S10.

[0038] If it is determined in the registration possibility determination process that the learned target data can be registered (step S14: Y), the process proceeds to step S21. If the learned target data cannot be registered (step S14: N), the process proceeds to step S15. In step S15, the HMI control unit 50 determines whether the help button 49 has been operated. If the help button 49 has not been operated (step S15: N), the process returns to step S15. If the help button 49 has been operated (step S15: Y), the process proceeds to step S16. In step S16, the HMI control unit 50 determines whether the limiting factor for not registering the learned target data is a user factor. If the limiting factor is a user factor (step S16: Y), the process proceeds to step S17. If the limiting factor is an environmental factor (step S16: N), the process proceeds to step S18. In step S17, the HMI control unit 50 displays the first help screen 40b. Then, the process proceeds to step S19. In step S18, the HMI control unit 50 displays the second help screen 40c. Then, the process proceeds to step S19.

[0039] In step S19, the HMI control unit 50 determines whether the back button 47 on the first help screen 40b or the second help screen 40c has been operated. If the back button 47 has not been operated (step S19: N), the process returns to step S19. If the back button 47 has been operated (step S19: Y), the process proceeds to step S20. In step S20, the HMI control unit 50 determines whether the limiting factor has been resolved. If the limiting factor has not been resolved (step S20: N), the process returns to step S10. If the limiting factor has been resolved (step S20: Y), the process proceeds to step S21.

[0040] In step S21, the HMI control unit 50 displays the registration guidance screen 40a on the display device of the HMI 13. In step S22, the HMI control unit 50 determines whether or not the end button 45 has been operated. If the end button 45 has been operated (step S22: Y), the registration process of the target parking position 31 ends. If the end button 45 has not been operated (step S22: N), the process proceeds to step S23. In step S23, the HMI control unit 50 determines whether or not the registration button 44 has been operated. If the registration button 44 has not been operated (step S23: N), the process returns to step S22. If the registration button 44 has been operated (step S23: Y), the process proceeds to step S24. In step S24, the map generation unit 55 stores the learned target data in the storage device 19b. Thereafter, the registration process of the target parking position 31 ends.

[0041] (Effects of the embodiment) (1) When registering learned target data in the storage device 19b, the controller 19 determines whether there are any limiting factors that prevent the learned target data from being registered in the storage device 19b, and if there are any limiting factors, the controller 19 does not register the learned target data in the storage device 19b. If there are any limiting factors, the controller 19 displays the environmental factors on the display device if there are any limiting factors that depend on the environment of the vehicle, and if there are limiting factors that depend on the user, the controller 19 displays the user factors on the display device. This allows the user to determine the limiting factors that prevent the learned target data from being registered when the learned target data cannot be registered, making it easier for the user to deal with situations where the target parking position cannot be registered.

[0042] (2) When environmental factors and user factors exist simultaneously, the controller 19 may display either the environmental factors or the user factors, but not the other. This allows the controller 19 to determine whether to prioritize the environmental factors or the user factors depending on the characteristics of the factors that prevent the learned target data from being registered. For example, the controller 19 may display the environmental factors prior to the user factors. This allows the user to be notified of environmental factors that are difficult for the user to resolve. (3) The environmental factors may include at least one of the following: the number of feature points around the target parking position is less than a predetermined value; the lighting conditions around the target parking position are less than a predetermined condition; or the clearance around the target parking position is less than a predetermined distance. This allows the user to be notified of the environmental factors that prevent the learned target data from being registered in the storage device 19b.

[0043] (4) The user factor may be that at least one of the following conditions (A) to (D) is satisfied when the host vehicle is driven near the target parking position in order to register the learned target data in the storage device: (A) The door mirrors of the host vehicle 1 were folded down. (B) The door of the host vehicle 1 was open. (C) Wheel spin of the host vehicle 1 was detected. (D) The vehicle speed of the host vehicle 1 was equal to or greater than a threshold value. This makes it possible to inform the user of the user factor that prevented the learned target data from being registered in the storage device 19b.

[0044] (5) When the limiting factor is resolved, the controller 19 may display a notification on the display device prompting the user to perform an operation to register the learned target data in the storage device 19b. As a result, the learned target data can be registered in the storage device 19b immediately when the limiting factor is resolved and the learned target data can be registered in the storage device 19b. (6) When the limiting factor is resolved after redoing the operation of parking the vehicle at the target parking position, a notification may be displayed on the display device prompting the user to perform an operation to register the learned target data in the storage device 19b. As a result, after the limiting factor is resolved, the information necessary for generating the learned target data can be reacquired and the learned target data can be registered in the storage device 19b.

[0045] 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.

[0046] 1...Own vehicle, 10...Parking assistance device, 11...Positioning device, 12...Map database, 13...Human machine interface, 14...Shift switch, 15...External sensor, 16...Vehicle sensor, 17...Parking switch, 19...Controller, 19a...Processor, 19b...Storage device, 20...Parking brake, 21a...Steering actuator, 21b...Accelerator actuator, 21c...Brake actuator, 50...HMI control unit, 51...Parking assistance control unit, 52...Image conversion unit, 53...Self-position calculation unit, 54...Target detection unit, 55...Map generation unit, 56...Map data, 57...Target parking position detection unit, 59...Target trajectory generation unit, 60...Steering control unit, 61...Vehicle speed control unit

Claims

1. A parking assistance method for assisting a vehicle in parking at a target parking position, comprising: Detecting targets present around the target parking position in advance, and registering data representing a relative positional relationship between the detected targets and the target parking position in a storage device as learned target data; When moving the host vehicle to the target parking position after registering the learned target data in the storage device, detecting positions of surrounding targets that are targets present around the host vehicle; Calculating a relative positional relationship between the target parking position and the current position of the vehicle based on the learned target object data and the positions of the surrounding targets; Calculating a travel trajectory from the current position of the vehicle to the target parking position based on the calculated relative position relationship; and assisting the host vehicle in parking at the target parking position based on the travel trajectory, When registering the learned target data in a storage device, if a limiting factor exists, the learned target data is not registered in the storage device, and if an environmental factor depending on an environment of the vehicle exists as the limiting factor, the environmental factor is displayed on a display device, and if a user factor depending on a user exists as the limiting factor, the user factor is displayed on the display device. A parking assistance method comprising:

2. 2. The parking assistance method according to claim 1, wherein, when the environmental factor and the user factor exist simultaneously, one of the environmental factor and the user factor is displayed, and the other is not displayed.

3. 3. The parking assistance method according to claim 2, wherein the environmental factors are displayed with priority over the user factors.

4. 4. The parking assistance method according to claim 1, wherein the environmental factors include at least one of the following: the number of feature points around the target parking position is less than a predetermined value; the lighting conditions around the target parking position are less than a predetermined condition; or the clearance around the target parking position is less than a predetermined distance.

5. The user factors include, when the host vehicle is driven near the target parking position in order to register the learned target data in the storage device, satisfying the following conditions (A) to (D): (A) The door mirrors of the vehicle were retracted. (B) The door of the vehicle was open; (C) The wheels of the vehicle are spinning. (D) the vehicle speed of the host vehicle is equal to or greater than a threshold value; 4. The parking assistance method according to claim 1, wherein at least one of the following is satisfied:

6. The parking assistance method according to any one of claims 1 to 3, characterized in that, when the limiting factor is resolved, a notification is displayed on the display device prompting the user to register the learned target data in the storage device.

7. The parking assistance method according to any one of claims 1 to 3, characterized in that, when the limiting factor is resolved after redoing the operation of parking the vehicle at the target parking position, a notification is displayed on the display device urging the user to register the learned target data in the storage device.

8. A parking assistance device that assists in parking a vehicle at a target parking position, a sensor for detecting targets around the host vehicle; A storage device; a display device; and a controller that detects targets present around the target parking position in advance, and registers data representing a relative positional relationship between the detected targets and the target parking position in the storage device as learned target data, and when moving the host vehicle to the target parking position after registering the learned target data in the storage device, detects positions of surrounding targets which are targets present around the host vehicle, and calculates a relative positional relationship between the target parking position and a current position of the host vehicle based on the learned target data and the positions of the surrounding targets, and calculates a travel trajectory from the current position of the host vehicle to the target parking position based on the calculated relative positional relationship, and assists the host vehicle in parking at the target parking position based on the travel trajectory, wherein the controller: When registering the learned target data in a storage device, if a limiting factor exists, the learned target data is not registered in the storage device, and if an environmental factor depending on an environment of the vehicle exists as the limiting factor, the environmental factor is displayed on a display device, and if a user factor depending on a user exists as the limiting factor, the user factor is displayed on the display device. A parking assistance device characterized by: