Parking assistance method and parking assistance device

Abstract

This parking assistance method includes: extracting target objects around a target parking position (30) from surrounding environment data obtained by detecting the surrounding environment of the vehicle (1), and storing the extracted target objects as learned target objects together with the target parking position (30) in a storage device; and assisting in the parking of the vehicle (1) at the target parking position (30) on the basis of the learned target objects when parking the vehicle (1) at the target parking position (30) after storing the learned target objects in the storage device. When the length of a forward section (31a), in which the vehicle has moved forward, among data detection sections (31a, 31r), in which the vehicle has traveled and obtained surrounding environment data, is equal to or greater than a predetermined threshold, the extracted target object is stored as a learned target object, and when the length of the forward section (31a) is less than the predetermined threshold, the extracted target object is not stored as a learned target object.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 below describes a parking method for controlling a vehicle according to a previously stored parking route. In this parking method, the parking route is not stored when the parking environment parameters at the time of storing the parking route do not satisfy the preset environmental conditions.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In parking assistance where landmarks around a target parking position are stored together with the target parking position in advance and parking of the host vehicle to the target parking position is assisted based on the stored landmarks, if the landmarks are not stored along an appropriate parking route, even if the target parking position is stored, parking assistance may not be performed, and the user may feel dissatisfied. An object of the present invention is to avoid user dissatisfaction caused by the inability to perform parking assistance to a stored target parking position because landmarks are not stored along an appropriate parking route in parking assistance where landmarks around a target parking position are stored together with the target parking position in advance and parking of the host vehicle to the target parking position is assisted based on the stored landmarks.

Means for Solving the Problems

[0005] According to one aspect of the present invention, a parking assistance method is provided to assist in parking the vehicle at a target parking position. The parking assistance method includes: first, detecting the surrounding environment of the vehicle using the vehicle's sensors to extract objects around the target parking position from surrounding environment data obtained, and storing the extracted objects as learned objects in a storage device along with the target parking position; and assisting in parking the vehicle at the target parking position based on the learned objects when parking the vehicle at the target parking position after storing the learned objects in the storage device. Specifically, if the length of the forward section (the section in which the vehicle moves forward) within the data detection section (the section in which the vehicle travels and obtains surrounding environment data) is greater than or equal to a predetermined threshold, the extracted objects are stored as learned objects, and if the length of the forward section is not greater than or equal to the predetermined threshold, the extracted objects are not stored as learned objects. [Effects of the Invention]

[0006] According to the present invention, in a parking assistance system that stores landmarks around a target parking position along with the target parking position in advance and assists in parking the vehicle at the target parking position based on the stored landmarks, it is possible to avoid user dissatisfaction caused by the inability to provide parking assistance to the stored target parking position because landmarks along an appropriate parking path are not stored. The objectives and advantages of the present invention are embodied and achieved using the elements and combinations thereof set forth in the claims. Both the general description above and the detailed description below are merely illustrative and descriptive, and should be understood not to limit the invention in any way that would be limited by the claims. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows a schematic configuration example of a parking assistance device according to an embodiment. [Figure 2] (a) and (b) are schematic diagrams illustrating parking assist control. [Figure 3] This is an explanatory diagram of the parking assistance method according to the first embodiment. [Figure 4] This is a flowchart of the parking assistance method according to the first embodiment. [Figure 5]Figure 1 is a block diagram showing an example of the controller's functional configuration. [Figure 6] (a) to (c) are explanatory diagrams of the permission conditions for allowing the registration of trained target data. [Figure 7] This is a flowchart of the parking assistance method according to the second embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) (composition) Figure 1 is a diagram showing a schematic configuration example of a parking assistance device according to an embodiment. The 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 assists in driving along a target parking path from the vehicle 1's current position to the target parking position. For example, automatic driving may be performed to control the vehicle 1 so that it drives along its target parking path to the target parking position. Automatic driving that controls the vehicle 1 to drive along its target parking path to the target parking position means controlling all or part of the steering angle, driving force, and braking force of the vehicle 1 to automatically perform all or part of driving along the target parking path. In addition, parking of the vehicle 1 may be assisted by displaying the target parking path and the vehicle 1's current position on a display device that can be seen by the user (e.g., the driver or other occupant) in the 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 Satellite System (GNSS) receiver. Map data is stored in the map database (map DB) 12. The map data stored in the map database 12 may be, for example, high-precision map data suitable for navigation or autonomous driving. The Human-Machine Interface (HMI) 13 is an interface device that exchanges information between the parking assist device 10 and the user. For example, the HMI 13 may be equipped with a display device that is visible to the user as an interface for presenting visual information to the user. The HMI 13 may also be equipped with a speaker or buzzer as an interface for presenting auditory information to the user. Furthermore, the HMI 13 may be equipped with an interface (touch panel, buttons, switches, levers, dials, keyboard, etc.) for receiving operational input from the user.

[0010] The shift switch (shift SW) 14 is a switch used by the driver or the parking assist device 10 to switch the shift position of the vehicle 1. The external sensor 15 detects the surrounding environment of the vehicle 1 within a predetermined distance range from the vehicle 1 and generates surrounding environment data, which is data of the detection results of the surrounding environment. For example, the external sensor 15 may detect the relative position of objects present around the vehicle 1 and the vehicle 1, the distance between the vehicle 1 and the objects, the direction in which the objects are located, etc., as the surrounding environment of the vehicle 1. For example, the external sensor 15 may include a camera that photographs the surrounding environment of the vehicle 1, and may generate surrounding environment data from the surrounding images obtained by photographing the area around the vehicle 1. Alternatively, the external sensor 15 may include a distance measuring device such as a laser rangefinder, radar, LiDAR (Light Detection and Ranging), or sonar, and may generate surrounding environment data from distance measurement data of the area around the vehicle 1 measured by these distance measuring devices.

[0011] The vehicle sensor 16 detects various information (vehicle information) of the vehicle 1. For example, the vehicle sensor 16 may include a wheel speed sensor that detects the rotational speed of the vehicle 1's wheels, a vehicle speed sensor that detects the vehicle 1's travel speed, a three-axis acceleration sensor that detects the vehicle 1's acceleration (including deceleration) in three axes, and sensors that detect the steering angle of the steering wheel and the steering angle of the steering wheels. The parking switch (parking SW) 17 is a switch for activating the parking assistance control provided by the parking assistance device 10.

[0012] The controller 19 is an electronic control unit that performs parking assistance control of the 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, etc. 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 vehicle 1 according to user operation or control signals from the controller 19. The steering actuator 21a controls the steering direction and amount of the steering mechanism of the vehicle 1 in accordance with the control signal from the controller 19. The accelerator actuator 21b controls the accelerator opening of the drive unit, such as the engine or drive motor, in accordance with the control signal from the controller 19. The brake actuator 21c activates the braking unit in accordance with the control signal from the controller 19.

[0013] Next, the parking assistance control by the controller 19 will be explained. Figures 2(a) and 2(b) are schematic diagrams illustrating the parking assistance control. When using the parking assistance control, the target parking position 30 in which the vehicle 1 should be parked is registered in advance with the parking assistance device 10. Specifically, landmarks existing around the target parking position 30 are extracted and stored (registered) in the storage device 19b in advance. In the following explanation, landmarks around the target parking position 30 stored in the storage device 19b will be referred to as "learned landmarks". In Figure 2(a), the circle plots schematically represent learned landmarks. When registering the target parking position 30 with the parking assistance device 10, the user performs an operation to instruct the registration of the target parking position 30 (hereinafter sometimes referred to as the "registration operation"). For example, the registration operation may be an operation to switch the shift position to the parking range, or it may be an operation of the parking switch 17 when the shift position is in the parking range.

[0014] For example, when the user parks the host vehicle 1 at the target parking position 30 in manual driving, the controller 19 stores the learned object landmarks in the storage device 19b. In the example of Fig. 2(a), when parking the host vehicle 1 at the target parking position 30, the host vehicle 1 is advanced along the parking path 31a on the passage PW that travels toward the entrance of the target parking position 30, and the host vehicle 1 is turned around at the turning point 32 to change the shift position of the host vehicle 1 from the forward driving position (e.g., drive range or brake range) to the reverse driving position, and then the host vehicle 1 is reversed along the parking path 31r and driven to the target parking position 30. "Turning around" refers to an operation of switching the shift position of the vehicle between the forward driving position and the reverse driving position. For example, the controller 19 extracts object landmarks around the target parking position 30 from the ambient environment data obtained by detecting the ambient environment of the host vehicle 1 with the external sensor 15 and stores them as learned object landmarks. For example, object landmarks may be detected from the ambient image obtained by photographing the surroundings of the host vehicle 1 with a camera. For example, points (feature points) having features in the form of edges or shapes where the luminance of adjacent pixels changes by a predetermined amount or more, such as edges and corners of object landmarks such as road markings, road boundaries, and obstacles on the captured image obtained by photographing with a camera, may be detected as object landmarks.

[0015] The controller 19 stores learned object landmark data related to the learned object landmarks in the storage device 19b. For example, the learned object landmark data may include data representing the feature amounts of the learned object landmarks (hereinafter referred to as "feature amount data") and data on the relative positional relationship between the target parking position 30 and the learned object landmarks (hereinafter referred to as "relative position data"). As the relative position data, for example, the relative position of the learned object landmark with respect to the target parking position 30 may be stored. The coordinates of the learned object landmark and the target parking position 30 in a coordinate system with a fixed point as a reference point (hereinafter referred to as "map coordinate system") may be stored.

[0016] Figure 2(b) is an explanatory diagram of an example of the process during parking support. When an operation by the user (hereinafter sometimes referred to as the "activation operation") that instructs the activation of the parking support control of the host vehicle 1 is performed, the controller 19 starts the parking support control of the host vehicle 1. The activation operation may be an operation of the parking switch 17 by the user. The controller 19 may automatically start the parking support control when the host vehicle 1 approaches the registered target parking position 30.

[0017] When the parking support control starts, the controller 19 extracts targets around the host vehicle 1 using the external sensor 15. In the following description, the targets around the host vehicle 1 extracted during parking support are referred to as "surrounding targets". In Figure 2(b), the triangular plots represent the surrounding targets. The controller 19 detects the target parking position 30 by matching the learned targets and the surrounding targets and associating the same feature points with each other. For example, based on the relative positional relationship between the surrounding target detected during parking support and the host vehicle 1, and the relative positional relationship between the learned target associated with the surrounding target and the target parking position 30, the relative position of the host vehicle 1 with respect to the target parking position 30 is calculated.

[0018] For example, the controller 19 calculates the position of the target parking position 30 in a coordinate system (hereinafter referred to as the "vehicle coordinate system") based on the current position of the host vehicle 1. When the coordinates of the learned target and the target parking position 30 in the map coordinate system are stored in the storage device 19b, the coordinates of the target parking position 30 in the map coordinate system may be converted into the coordinates in the vehicle coordinate system based on the position of the surrounding target detected during parking support and the position of the learned target in the map coordinate system. The self-position of the host vehicle 1 in the map coordinate system may be obtained based on the position of the surrounding target detected during parking support and the position of the learned target in the map coordinate system, and the relative position of the host vehicle 1 with respect to the target parking position 30 may be calculated from the difference between the coordinates of the host vehicle 1 and the coordinates of the target parking position 30 in the map coordinate system. The controller 19 calculates a target parking path 34 from the current position 33 of the vehicle 1 to the target parking position 30, based on the relative position of the vehicle 1 to the target parking position 30. The controller 19 performs parking assistance control of the vehicle 1 based on the calculated target parking path 34.

[0019] In this type of parking assistance method, if learned targets (circle plots) along an appropriate parking path cannot be memorized during the stage where learned targets are memorized (Figure 2(a)), then in the stage where parking assistance is performed (Figure 2(b)), the overlapping area between the region where detected surrounding targets (triangle plots) around the vehicle 1 are distributed and the region where learned targets are distributed will become small, potentially making it impossible to match a sufficient number of surrounding targets with the learned targets. For example, as shown in Figure 2(a), parking paths 31a and 31 r If a learned target is memorized along the same path, and the section 31a in which the vehicle 1 advances along the passage PW to the turning point 32 is short, then the vehicle 1 will not be able to detect surrounding targets that can be matched with the learned target until it approaches the target parking position 30. As a result, it becomes difficult to determine the relative position of the vehicle 1 with respect to the target parking position 30, and even though the target parking position 30 is registered in the storage device 19b, parking assistance to the target parking position 30 cannot be provided, which may cause dissatisfaction to the user. Therefore, in the parking assistance method of the first embodiment, while acquiring ambient environmental data for extracting learned targets, the storage of learned targets is permitted only if the length of the forward section, which is the section in which the vehicle 1 moved forward, is greater than or equal to a predetermined threshold within the section in which the vehicle 1 traveled (hereinafter sometimes referred to as the "data detection section"). For example, the predetermined threshold may be set to half the length of the data detection section or a fixed value such as 20m.

[0020] Figure 3 is an explanatory diagram of the parking assistance method of the first embodiment. In the example of Figure 3, when a learned target is detected and stored in the storage device 19b, the system acquires surrounding environment data and extracts the learned target in a forward section 31a, where the vehicle 1 moves forward along the parking path to the turning point 32, and in a reverse section 31r, where the vehicle 1 moves backward along the parking path from the turning point 32 to the target parking position 30 (i.e., the data detection section includes the forward section 31a and the reverse section 31r). The controller 19 stores targets extracted from the surrounding environment data acquired in the forward section 31a and the reverse section 31r as learned targets in the memory device 19b if the length La of the forward section 31a is greater than or equal to a predetermined threshold Lth. Conversely, if the length La of the forward section 31a is not greater than or equal to the predetermined threshold Lth, the controller 19 does not store targets extracted from the surrounding environment data acquired in the forward section 31a and the reverse section 31r as learned targets in the memory device 19b.

[0021] This allows the system to memorize learned landmarks along the parking path that the vehicle 1 would have traveled along the passage PW toward the target parking position 30, before the vehicle 1 reaches near the target parking position 30. Therefore, in the scenario where parking assistance is performed (Figure 2(b)), sufficient overlap can be ensured between the area where detected surrounding objects (triangle plots) are distributed and the area where learned objects (circle plots) are distributed before the vehicle 1 reaches near the target parking position 30. As a result, it is possible to suppress the difficulty in determining the relative position of the vehicle 1 with respect to the target parking position 30, making parking assistance to the target parking position easier and avoiding user dissatisfaction caused by the inability to perform parking assistance even though the target parking position is memorized. Note that the length of the data detection section and the forward section 31a may be the distance traveled by the vehicle 1, or the travel time.

[0022] Figure 4 is a flowchart showing how to register the target parking position 30 in the parking assistance device 10 in advance in the parking assistance method of the first embodiment. In step S1, when the user manually parks the vehicle 1 at the target parking position 30, the controller 19 acquires ambient environment data from the external sensor 15 for extracting learned targets. In step S2, the controller 19 determines the current direction of travel of the vehicle 1. In step S3, the controller 19 extracts targets from the ambient environment data acquired in step S1 and temporarily stores the extracted targets in a buffer.

[0023] In step S4, the controller 19 determines whether a registration operation to instruct the registration of the target parking position 30 has been performed. If the registration operation is not performed (step S4:N), the process returns to step S1. If the registration operation is performed (step S4:Y), the process proceeds to step S5. In step S5, the controller 19 determines that if the length of the forward section in which the vehicle 1 moved forward within the data detection section in which the vehicle 1 traveled while acquiring surrounding environment data is not greater than or equal to a predetermined threshold Lth (step S5:N), the process ends. In this case, the learned target is not stored in the storage device 19b. If the length of the forward section is greater than or equal to the predetermined threshold Lth (step S5:Y), the process proceeds to step S6. In step S6, the controller 19 stores the temporarily stored target as a learned target in the storage device 19b. The process then ends.

[0024] (Second Embodiment) Figure 5 is a block diagram of an example of the functional configuration of the controller 19. When the HMI control unit 50 detects a registration operation by the user, it outputs a map generation command to the map generation unit 55 to store the learned target data in the storage device 19b. The image conversion unit 52 converts the image captured by the camera into an overhead view image from a virtual viewpoint directly above the vehicle 1. The overhead view image is an example of the "surrounding environment data" described in the claims. The image conversion unit 52 converts the captured image into an overhead view image at predetermined intervals I. For example, the image conversion unit 52 may generate an overhead view image every time the vehicle 1 travels a predetermined distance (e.g., 1 m). Or it may generate an overhead view image every time the vehicle travels for a predetermined amount of time (e.g., 1 second). Each of these overhead view images acquired when the vehicle 1 is at a different position is sometimes referred to as a "frame," and the number of overhead view images is sometimes referred to as the "number of frames." The product of the number of frames and the predetermined interval I is equal to the travel distance or travel time required to generate the overhead view images for that number of frames.

[0025] The self-position calculation unit 53 calculates the current position of the vehicle 1 on the map coordinate system as its own position by odometry (e.g., dead reckoning) based on vehicle information output from the vehicle sensor 16. The self-position calculation unit 53 also detects the direction of travel of the vehicle 1. For example, the self-position calculation unit 53 may detect the direction of travel of the vehicle 1 based on the shift position of the shift switch 14 or the detection result of the vehicle speed sensor. The target detection unit 54 detects targets from the overhead image output from the image conversion unit 52. The target detection unit 54 may detect the position of the target's feature points and their image features. The target detection unit 54 outputs the detected feature point positions and image features as target data to the map generation unit 55 and the target parking position detection unit 57. In addition, the self-position obtained 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 target detection.

[0026] The map generation unit 55 temporarily stores the target data and self-position data output from the target detection unit 54 in a buffer while the vehicle 1 is traveling along its route. When the number of frames in which target data has been stored in the buffer reaches the first upper limit Nfu1, the map generation unit 55 deletes the target data detected from the oldest frame from the buffer and stores the target data detected from the new frame. Furthermore, the map generation unit 55 classifies the target data output from the target detection unit 54 into target data detected from frames acquired in the forward section 31a and target data detected from frames acquired in the reverse section 31r.

[0027] In the following explanation, frames acquired in forward section 31a will be referred to as "forward section frames," and target data detected from forward section frames will be referred to as "forward section data." Similarly, frames acquired in backward section 31r will be referred to as "backward section frames," and target data detected from backward section frames will be referred to as "backward section data." When the number of forward section frames accumulated in the buffer reaches a second upper limit number Nfu2, which is smaller than the first upper limit number Nfu1, the map generation unit 55 deletes the oldest forward section data from the buffer and accumulates new forward section data.

[0028] 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 30 begins), it performs a determination process to determine whether or not to register the learned target data. In the determination process to determine whether or not to register the learned target data, the map generation unit 55 determines whether or not to satisfy the permission conditions (hereinafter referred to as "permission conditions") that permit the registration of the learned target data to the storage device 19b, based on the number of forward section frames in which the target data is stored in the buffer and the number of U-turns in the data detection section. That is, it determines whether or not to satisfy the permission conditions based on the length of the forward section 31a in which the target data is temporarily stored in the buffer and the number of U-turns. If the permission conditions are satisfied, the map generation unit 55 generates learned target data based on the target data and self-position data temporarily stored in the buffer, and stores the generated learned target data as map data 56 in the storage device 19b. If the permission conditions are not satisfied, the map generation unit 55 does not store the learned target data in the storage device 19b (i.e., it does not permit the storage of learned target data in the storage device 19b).

[0029] Figures 6(a) to 6(c) are explanatory diagrams of the permit conditions. Reference numerals 31a1 to 31a3 indicate forward sections included in the data detection section, reference numerals Na1 to Na3 indicate the number of frames detected in forward sections 31a1 to 31a3, reference numerals 31r1 to 31r3 indicate reverse sections included in the data detection section, reference numerals Nr1 to Nr3 indicate the number of frames detected in reverse sections 31r1 to 31r3, and reference numerals 32a to 32e indicate the turning points where vehicle 1 made a U-turn in the data detection section. In the following explanation, the forward sections 31a1 to 31a3 will be collectively referred to as "forward section 31a," the number of frames in forward section 31a will be collectively referred to as "frame count Na," the backward sections 31r1 to 31r3 will be collectively referred to as "backward section 31r," the number of frames in backward section 31r will be collectively referred to as "frame count Nr," and the turning points 32a to 32e will be collectively referred to as "turning point 32."

[0030] Figure 6(a) shows a parking route in which the vehicle 1 moves forward in forward section 31a1, then continues forward in forward section 31a2, then makes a U-turn at U-turn point 32a, and then reverses in reverse section 31r1 to reach the target parking position 31. As described above, when the number of frames in which the map generation unit 55 has temporarily stored target data in the buffer reaches the first upper limit number Nfu1, it deletes the target data detected from the oldest frame from the buffer when storing target data detected from a new frame. Therefore, the sum of the lengths of the forward sections 31a1 and 31a2 and the reverse section 31r1 stored as learned target data is limited to a predetermined length corresponding to the first upper limit number Nfu1 (i.e., Na1 + Na2 + Nr1 ≤ Nfu1). The predetermined length corresponding to the first upper limit number Nfu1 is an example of the "first predetermined length" described in the claims.

[0031] Furthermore, when the number of forward section frames in which forward section data has been stored in the buffer reaches the second upper limit number Nfu2, the map generation unit 55 deletes the oldest forward section data from the buffer when storing new forward section data. Therefore, when the number of frames Na2 of forward section 31a2, which the vehicle 1 traveled after forward section 31a1, reaches the second upper limit number Nfu2, the map generation unit 55 deletes the forward section data acquired in forward section 31a1 from the buffer. For this reason, the forward section data acquired in forward section 31a1 is not stored as learned target data. In other words, the total length of forward sections 31a from which targets to be stored as learned targets are extracted is limited to a predetermined length corresponding to the second upper limit number Nfu2 (i.e., Na ≤ Nfu2). The predetermined length corresponding to the second upper limit number Nfu2 is an example of the "second predetermined length" described in the claims.

[0032] For example, the map generation unit 55 may determine that the permission conditions are satisfied if the following condition (C1) is met. (C1) The total number of frames Na in the forward section 31a where the forward section data is stored in the buffer is equal to or greater than a predetermined threshold Nth1 (i.e., the total length of the forward section 31a in the data detection section is equal to or greater than the threshold). For example, the map generation unit 55 may determine that the permit conditions are satisfied if both the above condition (C1) and the following condition (C2) are met. (C2) The vehicle speed of vehicle 1 in the data detection section is below the predetermined speed.

[0033] Figure 6(b) shows a parking route in which vehicle 1 moves forward through forward section 31a1, then continues forward through forward section 31a2, then makes a U-turn at U-turn point 32a and moves backward through reverse section 31r1, then makes a U-turn at U-turn point 32b and moves forward through forward section 31a3, then makes a U-turn at U-turn point 32c and moves backward through reverse section 31r2 to reach the target parking position 31. For example, the map generation unit 55 may determine that the permit conditions are satisfied if both the above condition (C1) and the following condition (C3) are met, or if all of the above conditions (C1) and (C2) and the following condition (C3) are met. (C3) Of the forward sections 31a1 and 31a2 prior to the first reversal point 32a, the number of frames Na2 in forward section 31a2 in which forward section data remains in the buffer is greater than or equal to a predetermined threshold Nth2 (i.e., of the forward sections 31a1 and 31a2 prior to the first reversal point 32a, the length of the section in which a frame from which a target that can be stored as a learned target has been extracted is greater than or equal to a predetermined length). For example, if the total number of frames in the section after the first reversal point 32a (Nr1 + Na3 + Nr2 in the example of Figure 6(b)) is greater than the difference obtained by subtracting the predetermined threshold Nth2 from the second upper limit Nfu2 (Nfu2 - Nth2), then the number of frames in the forward section 31a2, for which forward section data remains in the buffer as targets to be stored as learned targets, becomes smaller than the predetermined threshold Nth2. In this case, condition (C3) is not satisfied. The predetermined threshold Nth2 may be the same as the predetermined threshold Nth1, or it may be smaller than the predetermined threshold Nth1.

[0034] Figure 6(c) shows the parking path in which vehicle 1 moves forward in forward section 31a1, then reverses in reverse section 31r1 by making a U-turn at U-turn point 32a, then moves forward in forward section 31a2 by making a U-turn at U-turn point 32b, then reverses in reverse section 31r2 by making a U-turn at U-turn point 32c, then moves forward in forward section 31a3 by making a U-turn at U-turn point 32d, and then reverses in reverse section 31r3 by making a U-turn at U-turn point 32e to reach the target parking position 31. For example, the map generation unit 55 may determine that the permit conditions are satisfied if both the above condition (C1) and the following condition (C4) are met, or if all of the above conditions (C1) and (C2) and the following condition (C4) are met, or if all of the above conditions (C1) to (C3) and the following condition (C4) are met. (C4) The number of times vehicle 1 made a U-turn in the data detection section is less than or equal to the predetermined number Cc. For example, if the predetermined number of turns Cc is set to 3, the number of turning points 32a to 32e in the example parking route in Figure 6(c) is 5 (number of turning points "5"), so condition (C4) is not satisfied.

[0035] Furthermore, the predetermined threshold Nth1 may be set to a different value for perpendicular parking, where the vehicle 1 is parked perpendicular to the direction of travel of the passage PW towards the target parking position 30, and parallel parking, where the vehicle 1 is parked parallel to the direction of travel of the passage PW. For example, in the case of parallel parking, the forward section 31a tends to be shorter than in the case of perpendicular parking, so setting a smaller predetermined threshold Nth1 than in the case of perpendicular parking can suppress the difficulty in allowing the storage of learned target data. Similarly, the predetermined number of times Cc may be set to a different value for perpendicular parking and parallel parking. For example, in the case of parallel parking, a larger predetermined number of times Cc may be set than in the case of perpendicular parking. Refer to Figure 5. When it is determined that the permission conditions are met, the map generation unit 55 generates learned target data. For example, the map generation unit 55 acquires the target data temporarily stored in the buffer and the position of the vehicle 1 on the map coordinate system synchronized with the target data. The map generation unit 55 also acquires the position information of the target parking position 30 in the map coordinate system. For example, when the vehicle 1 is located at the target parking position 30, the position calculated by the self-position calculation unit 53 may be acquired as the position information of the target parking position 30.

[0036] The map generation unit 55 generates relative position data based on the positions of feature points included in the target data, the position information of the vehicle 1 synchronized with these points, and the position information of the target parking position 30. The map generation unit 55 acquires feature data from the target data stored in the buffer. The map generation unit 55 generates trained target data including this relative position data and feature data, and stores it in the storage device 19b as map data 56. On the other hand, if the map generation unit 55 determines that the permission conditions are not met, it does not store the learned target data in the storage device 19b. In this case, the HMI control unit 50 may notify the user of the vehicle 1 (e.g., the occupant) that the learned target data will not be registered. For example, the HMI control unit 50 may display visual information on the display device of the HMI 13 indicating that the learned target data will not be registered. Alternatively, the HMI 13 may output auditory information indicating that the learned target data will not be registered.

[0037] When the HMI control unit 50 detects a user's operation to activate parking assistance control, it outputs a control start command to the parking assistance control unit 51 to initiate parking assistance control to the target parking position. When the parking assistance control unit 51 receives a control start command from the HMI control unit 50, it determines whether the current position of the vehicle 1 is near the registered target parking position 30. If the current position of the vehicle 1 is near the registered target parking position 30, the parking assistance control unit 51 executes parking assistance control. The parking assistance control unit 51 may also automatically start parking assistance control when the vehicle 1 approaches the registered target parking position 30. When the parking assistance control unit 51 starts parking assistance control, it outputs a parking position calculation command to the target parking position detection unit 57. Upon receiving the parking position calculation command, the target parking position detection unit 57 receives the target data output from the target detection unit 54 as target data for surrounding targets, and simultaneously receives the self-position of the vehicle 1 in the map coordinate system.

[0038] The target parking position detection unit 57 detects the target parking position 30 by matching learned targets with surrounding targets and associating targets with the same feature points. In other words, it determines whether or not the target parking position 30 can be detected based on whether or not the matching between the learned targets and surrounding targets is successful. If the matching is successful (i.e., the target parking position 30 is detected), the target parking position detection unit 57 calculates the relative position of the vehicle 1 with respect to the target parking position 30 based on the relative positional relationship between the surrounding targets and the vehicle 1 and the relative positional relationship between the learned targets associated with the surrounding targets and the target parking position 30. The target trajectory generation unit 59 calculates a target parking path from the current position of the vehicle 1 in the vehicle coordinate system to the target parking position 30. The target trajectory generation unit 59 calculates a target vehicle speed profile, which is the target value of the vehicle speed of the vehicle 1 along the target parking path. The steering control unit 60 controls the steering actuator 21a so that the vehicle 1 travels along the target parking path. The vehicle speed control unit 61 controls the accelerator actuator 21b and brake actuator 21c so that the vehicle speed of the vehicle 1 changes according to the target vehicle speed profile. When the vehicle 1 reaches the target parking position 30 and parking assistance control is completed, the parking assistance control unit 51 activates the parking brake 20 and switches the shift position to the parking range.

[0039] Figure 7 is a flowchart of the driving assistance method of the second embodiment. In step S10, the image conversion unit 52 of the controller 19 acquires the image captured by the camera as surrounding environment data when the user manually parks the vehicle 1 at the target parking position 30. In step S11, the self-position calculation unit 53 determines the current direction of travel of the vehicle 1. In step S12, the target detection unit 54 detects targets from the overhead image output from the image conversion unit 52. The map generation unit 55 temporarily stores the target data of the targets detected by the target detection unit 54 in a buffer. In step S13, the map generation unit 55 determines whether the number of frames in which the target data has been temporarily stored in the buffer exceeds the first upper limit number Nfu1. If the number of frames does not exceed the first upper limit number Nfu1 (step S13:N), the process proceeds to step S15. If the number of frames exceeds the first upper limit number Nfu1 (step S13:Y), the process proceeds to step S14. In step S14, the map generation unit 55 deletes the target data detected from the oldest frame from the buffer. The process then proceeds to step S15.

[0040] In step S15, the map generation unit 55 determines whether the vehicle 1 has traveled a predetermined interval I. If the vehicle 1 has traveled a predetermined interval I (step S15:Y), the process returns to step S10. If the vehicle 1 has not traveled a predetermined interval I (step S15:N), the process proceeds to step S16. In step S16, the HMI control unit 50 determines whether it has detected a target parking position registration operation. If no registration operation is detected (step S16:N), the process returns to step S15. If a registration operation is detected (step S16:Y), the process proceeds to step S17. In step S17, the map generation unit 55 determines whether the permission conditions are met. If the permission conditions are not met (step S17:N), the process ends without storing the learned target data in the storage device 19b. If the permission conditions are met (step S17:Y), the process proceeds to step S18. In step S18, the map generation unit 55 generates learned target data based on the target data and self-position data temporarily stored in the buffer, and stores the generated learned target data in the storage device 19b. The process then ends.

[0041] (modified version) (1) In the first embodiment described above, an example was given in which targets extracted from ambient environment data are temporarily stored in a buffer. However, the present invention is not limited to such specific examples. For example, ambient environment data may be temporarily stored in a buffer instead of targets, and targets may be extracted from the ambient environment data stored in the buffer after the registration operation is performed. Similarly, in the second embodiment, an example was given in which target data extracted from an overhead image is temporarily stored in a buffer. However, an overhead image may be temporarily stored in a buffer instead of target data, and target data may be extracted from the overhead image stored in the buffer after the registration operation is performed. (2) In the above embodiment, targets extracted from surrounding environment data detected in the data detection section where the driving distance or driving time from the target parking position is less than or equal to the first predetermined length are stored as learned targets, but the present invention is not limited thereto. Targets extracted from surrounding environment data detected in the section where the driving distance or driving time from the target parking position is longer than the first predetermined length may also be used as learned targets. In this case, the map generation unit 55 stores targets where the driving distance or driving time from the target parking position is less than or equal to the first predetermined length longer If the length of the forward section, which is the section in which the vehicle 1 moves forward within the section, is greater than or equal to a predetermined threshold, the extracted target is stored as a learned target. If the length of the forward section is not greater than or equal to the predetermined threshold, the extracted target does not need to be stored as a learned target.

[0042] (Effects of the embodiment) (1) The controller 19 first detects the surrounding environment of the vehicle 1 using the external sensor 15 and extracts objects around the target parking position from the surrounding environment data obtained. The controller 19 stores the extracted objects as learned objects along with the target parking position in the storage device 19b, and after storing the learned objects in the storage device 19b, the controller 1 parks the vehicle 1 at the target parking position. The controller 19 stores the extracted objects as learned objects if the length of the forward section (the section in which the vehicle 1 moved forward) within the data detection section (the section in which the vehicle 1 traveled and obtained surrounding environment data) is greater than or equal to a predetermined threshold. The controller 19 does not store the extracted objects as learned objects if the length of the forward section is not greater than or equal to the predetermined threshold.

[0043] This allows the system to memorize learned landmarks along the parking path that the vehicle 1 would have taken to reach the target parking position 30 before it reaches close to the target parking position 30. Therefore, when using the learned landmarks to determine the relative position of the vehicle 1 to the target parking position 30 during parking assistance, it is possible to suppress difficulties in determining the relative position, thus avoiding user dissatisfaction caused by the inability to provide parking assistance.

[0044] (2) When storing learned targets, the controller 19 registers relative position data representing the relative positional relationship between the learned targets and the target parking position in the storage device 19b. When parking the vehicle 1 to the target parking position after storing the learned targets in the storage device 19b, the controller 19 detects the positions of surrounding targets, which are targets that exist around the vehicle 1. Based on the relative position data and the positions of the surrounding targets, the controller 19 calculates the relative positional relationship between the target parking position and the current position of the vehicle 1. Based on the calculated relative positional relationship, the controller 19 calculates the driving trajectory from the current position of the vehicle 1 to the target parking position, and assists in parking the vehicle 1 to the target parking position based on the driving trajectory. This allows the user to utilize parking assistance control to help their vehicle park to a pre-registered target parking location.

[0045] (3) The controller 19 stores as learned targets when the length of the forward section, which is the section in which the vehicle 1 moves forward within the data detection section where the distance traveled from the target parking position or the travel time is less than or equal to a first predetermined length, is greater than or equal to a predetermined threshold. It does not need to store as learned targets when the length of the forward section is not greater than or equal to the predetermined threshold. By making the determination at a position close to the target parking position, a straight section can be secured at a position close to the target parking position, and the difficulty in determining the relative position of the vehicle 1 with respect to the target parking position near the target parking position can be suppressed. (4) The controller 19 may store as learned targets targets extracted from surrounding environment data detected in the data detection section where the driving distance or driving time from the target parking position is less than or equal to a first predetermined length. The controller may also store as learned targets targets extracted from surrounding environment data detected in the section which includes the forward section and the reverse section, which is the section in which the vehicle 1 reverses, as the section where the driving distance or driving time from the target parking position is less than or equal to a first predetermined length. This makes it possible to suppress an increase in the capacity for storing learned targets.

[0046] (5) The controller 19 does not need to store learned targets if the vehicle speed of its own vehicle 1 in the data detection section exceeds a predetermined speed. This prevents the registration of unclear learned target data due to the surrounding image becoming blurry or the accuracy of self-position estimation decreasing because of high vehicle speed. (6) The total length of the sections from which learned targets are extracted within the forward movement section may be less than or equal to the second predetermined length. By limiting the length of the forward movement section in this way, the matching process between learned targets and surrounding targets becomes easier when implementing parking assistance control. (7) The controller 19 may notify the occupants of its own vehicle 1 if it does not store a learned target. This allows the occupants to be informed that it is not possible to store a learned target along the appropriate route.

[0047] (8) The controller 19 does not need to store learned targets if the number of times the vehicle 1 makes U-turns in the data detection section is greater than a predetermined number. This prevents targets from being stored as learned targets along an inappropriate parking path when the vehicle 1 makes U-turns repeatedly in a narrow section. (9) The controller 19 does not need to store learned targets if the length of the section in which it detects ambient environment data for extracting targets that can be stored as learned targets from the forward section in which the vehicle 1 moves forward before the first U-turn in the data detection section is less than a predetermined length. This allows the controller to store learned targets over a sufficient range along the parking path in which the vehicle 1 moves forward until it is close to the target parking position. (10) The predetermined threshold can be set to a different value between the case of perpendicular parking, in which the vehicle 1 is parked perpendicular to the direction of travel of the passage leading to the target parking position, and the case of parallel parking, in which the vehicle 1 is parked parallel to the direction of travel. This makes it possible to set an appropriate predetermined threshold according to the type of parking. [Explanation of symbols]

[0048] 1...Own vehicle, 10...Parking assist device, 11...Positioning device, 12...Map database, 13...Human-machine interface, 14...Shift switch, 15...External environment 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 assist 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 that assists in parking one's own vehicle in a target parking position, Prior to this, the surrounding environment data obtained by detecting the surrounding environment of the vehicle using the vehicle's sensors is used to extract landmarks around the target parking position, and these extracted landmarks are stored in a memory device along with the target parking position as learned landmarks. This includes, when parking the vehicle at the target parking position after storing the learned target in the storage device, assisting the vehicle in parking at the target parking position based on the learned target, A parking assistance method characterized in that, within the data detection section which is the section in which the vehicle travels and obtains the surrounding environment data, if the length of the forward section which is the section in which the vehicle moves forward is greater than or equal to a predetermined threshold, the extracted object is stored as a learned object, and if the length of the forward section is not greater than or equal to the predetermined threshold, the extracted object is not stored as a learned object.

2. When storing the learned target, relative position data representing the relative positional relationship between the learned target and the target parking position is registered in the storage device. When parking the vehicle to the target parking position after storing the learned targets in the memory device, the positions of surrounding targets, which are targets present around the vehicle, are detected. Based on the relative position data and the positions of the surrounding objects, the relative positional relationship between the target parking position and the current position of the vehicle is calculated. Based on the calculated relative positional relationship, the driving trajectory from the vehicle's current position to the target parking position is calculated. Based on the aforementioned driving trajectory, the system assists in parking the vehicle at the target parking position. The parking assistance method according to feature 1.

3. The parking assistance method according to claim 1, characterized in that, in the data detection section, if the length of the forward section, which is the section in which the vehicle moves forward within the section where the driving distance or driving time from the target parking position is less than or equal to a first predetermined length, is greater than or equal to a predetermined threshold, the extracted target is stored as the learned target, and if the length of the forward section is not greater than or equal to the predetermined threshold, the extracted target is not stored as the learned target.

4. The parking assistance method according to claim 1 or 3, characterized in that the object extracted from the surrounding environment data detected in the data detection section in which the driving distance or driving time from the target parking position is less than or equal to a first predetermined length is stored as the learned object.

5. The parking assistance method according to claim 3, characterized in that, as a section in which the distance traveled from the target parking position or the travel time is less than or equal to the first predetermined length, the object extracted from the surrounding environment data detected in a section including the forward section and the reverse section which is the section in which the vehicle reversed is stored as the learned object.

6. The parking assistance method according to claim 1 or 3, characterized in that the learned target is not stored when the vehicle speed of the vehicle in the data detection section exceeds a predetermined speed.

7. The parking assistance method according to claim 1 or 3, characterized in that the total length of the sections from which the learned targets are extracted from the forward sections is less than or equal to a second predetermined length.

8. The parking assistance method according to claim 1 or 3, characterized in that the occupant of the vehicle is notified if the learned target is not stored.

9. The parking assistance method according to claim 1 or 3, characterized in that the learned target is not stored if the number of times the vehicle makes a U-turn in the data detection section exceeds a predetermined number.

10. The parking assistance method according to claim 1 or 3, characterized in that if the length of the section from which the surrounding environment data is obtained for extracting objects that can be stored as learned objects from the forward section in which the vehicle moves forward before the first reversal is performed in the data detection section is less than a predetermined length, the learned objects are not stored.

11. The parking assistance method according to claim 1 or 3, characterized in that the predetermined threshold is set to a different value between the case of perpendicular parking, in which the vehicle is parked perpendicular to the direction of travel of the passage toward the target parking position, and the case of parallel parking, in which the vehicle is parked parallel to the direction of travel.

12. A parking assist device that assists in parking the vehicle at a target parking position, A sensor for detecting the surrounding environment of the vehicle, Memory device and A controller that, in advance, detects the surrounding environment of the vehicle using the sensor and extracts objects around the target parking position from the surrounding environment data obtained, stores the extracted objects as learned objects along with the target parking position in a storage device, and assists in parking the vehicle at the target parking position based on the learned objects when the vehicle is parked at the target parking position after the learned objects have been stored in the storage device, Equipped with, The controller is characterized in that, within the data detection section which is the section in which the vehicle moves forward and obtains the surrounding environment data, the length of the forward section which is the section in which the vehicle moves forward is greater than or equal to a predetermined threshold, and the length of the forward section which is less than or equal to a predetermined threshold, the controller stores the extracted object as a learned object, and does not store the extracted object as a learned object if the length of the forward section is less than or equal to a predetermined threshold.

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