Parking assistance method and parking assistance device

Abstract

In this parking assistance method, information on a parking position (31) and a turnaround position (32), which is the position at which a vehicle made a turnaround, is acquired from a storage device (19b) in which information on the parking position (31) from when vehicles were parked and information on the turnaround position (32) from when the vehicles were parked at the parking position (31) were previously stored at the time of parking; a localized position (33), which is the current position of a host vehicle (1) is detected; and guidance (40a) indicating the parking position (31) as a candidate target parking position is provided to a user of the host vehicle (1) on the basis of at least the turnaround position (32) and the localized position (33).

Description

[Technical Field]

[0001] This invention relates to a parking assistance method and a parking assistance device. [Background technology]

[0002] Patent Document 1 below describes a parking assistance device that stores the target parking position in a parking operation performed in the past and guides the vehicle to a target parking position, enabling automatic driving to that position. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-133230 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, in the parking assistance device described in Patent Document 1, if there are multiple pre-stored parking target locations, the user must select the parking target location to be guided. The present invention aims to reduce the effort required for the user to select a parking target location when presenting the user with guidance for a pre-stored parking target location. [Means for solving the problem]

[0005] In one embodiment of the present invention, a parking assistance method acquires information on the parking position at the time of parking and information on the turning position, which is the position where the vehicle turned around when it was parked, from a storage device that was previously stored when the vehicle was parked. The system then detects the current position of the vehicle and guides the user of the vehicle to a parking position as a target parking position candidate based on at least the turning position and the vehicle's position. [Effects of the Invention]

[0006] According to the present invention, when presenting the user with guidance on pre-stored parking target locations, the user's operation of selecting a parking target location can be streamlined. 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) is a schematic diagram of the scene where the target parking position is registered, and (b) is a schematic diagram of the scene where parking assistance to the target parking position is performed. [Figure 3] This is a schematic diagram of an example of the first guidance screen. [Figure 4] This is a flowchart of the parking assistance method according to the first embodiment. [Figure 5] (a) and (b) are schematic diagrams illustrating an example of a method for detecting a parking position using pre-learned targets. [Figure 6] Figure 1 is a block diagram showing an example of the controller's functional configuration. [Figure 7] This is a schematic diagram of the parking position, first parking azimuth angle, turning position, and turning azimuth angle that are registered in advance prior to parking assistance. [Figure 8] This is a schematic diagram of an example of the second guidance screen. [Figure 9] This is a schematic diagram of the method for determining whether the detected parking position is appropriate. [Figure 10] 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. For example, the GNSS receiver may be a GPS receiver or the like. 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 an object 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 between the object existing around the host vehicle 1 and the host vehicle 1, the distance between the host vehicle 1 and the object, and the direction in which the object exists. 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 ranging device such as a laser rangefinder, radar, LiDAR (Light Detection and Ranging), or sonar. The vehicle sensor 16 detects various information (vehicle information) of 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 a sensor that detects the steering angle of the steering wheel or the steering angle of the steered wheels. The parking switch (parking SW) 17 is a switch for activating parking support control by the parking support device 10.

[0011] The controller 19 is an electronic control unit that performs parking support 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, when the processor 19a executes 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 according to a user operation or a control signal from the controller 19. The steering actuator 21a controls the steering direction and the amount of steering of the steering mechanism of the host vehicle 1 in response to a control signal from the controller 19. The accelerator actuator 21b controls the accelerator opening of a drive device that is an engine or a drive motor in response to a control signal from the controller 19. The brake actuator 21c operates the braking device in response to a control signal from the controller 19.

[0012] Next, the parking support control by the controller 19 will be described. The controller 19 executes parking support control to assist parking at a pre-registered target parking position. The target parking position is stored (registered) in a specific storage device in advance before the parking support of the host vehicle 1 is executed. FIG. 2(a) is a schematic diagram of a scene for registering the target parking position. When registering the target parking position, the vehicle (the host vehicle 1 in the example of FIG. 2(a)) is parked at the target parking position by manual driving in advance. In FIG. 2(a), the dashed line 30 indicates the parking trajectory when the host vehicle 1 is actually parked at the parking position 31 by manual driving, and the reference sign 32 indicates the turning position which is the position where the host vehicle 1 makes a turn in the parking trajectory 30. Note that "turning" refers to an operation of changing the shift position of the vehicle from the forward driving position to the reverse driving position. For example, the controller 19 may detect the occurrence of turning based on the state change of the shift switch 14. The controller 19 may acquire the position of the host vehicle 1 measured by the positioning device 11 at the time of the occurrence of turning as the turning position 32. Also, the controller 19 may acquire the position of the host vehicle 1 measured by the positioning device 11 when the parking operation of the host vehicle 1 by manual driving is completed as the parking position 31. For example, the controller 19 may determine that the parking operation is completed when the shift position of the vehicle becomes the parking range (P). The controller 19 registers the parking position 31 and the turning position 32 by associating the parking position 31 and the turning position 32 in a coordinate system with a fixed point as a reference point (hereinafter referred to as "map coordinate system") and storing them in a specific storage device.

[0013] The specific memory device that stores the parking position 31 and the turning position 32 may be, for example, memory device 19b, or it may be an external memory device (e.g., a cloud computer) of the vehicle 1. For example, the parking position 31 and turning position 32 acquired when another vehicle other than the vehicle 1 is manually driven to the parking position 31 may be stored in a memory device provided outside the vehicle 1 and the other vehicle. The vehicle 1 may receive the parking position 31 and turning position 32 stored in the external memory device via a communication device and use them to assist the parking of the vehicle 1. In the following description, the case in which the parking position 31 and the turning position 32 are registered in memory device 19b will be illustrated as an example. Refer to Figure 2(b). When performing parking assistance to parking position 31 as the target parking position, the controller 19 obtains the pre-registered parking position 31 and turning position 32 from the storage device 19b. The positioning device 11 also detects the current position of the vehicle 1, which is the self position 33. Based on the turning position 32 and the self position 33, the controller 19 presents guidance to the user regarding parking position 31 as a target parking position candidate. For example, if the turning position 32 is within a predetermined range 34 around the self position 33, the controller 19 may present guidance to the user regarding parking position 31 stored in association with the turning position 32. For example, if the distance D between the self position 33 and the turning position 32 is less than or equal to the distance threshold Dth, the controller 19 may present guidance to the user regarding parking position 31. The controller 19 may also provide guidance to the user regarding the parking position 31 based on the parking position 31 and its own position 33. For example, if the parking position 31 is located within a predetermined range 34 around the own position 33, the controller 19 may provide guidance to the user regarding the parking position 31. Alternatively, the controller 19 may provide guidance to the user regarding the parking position 31 based on the parking position 31, the turning position 32, and its own position 33. For example, if any position on the line segment connecting the parking position 31 and the turning position 32 is located within a predetermined range 34 around the own position 33, the controller 19 may provide guidance to the user regarding the parking position 31. For example, if the midpoint between the parking position 31 and the turning position 32 is located within a predetermined range 34 around the own position 33, the controller 19 may provide guidance to the user regarding the parking position 31. If there are multiple parking positions 31 that satisfy the above conditions, the controller 19 may provide guidance to all parking positions that satisfy the conditions, or to the positions in order of proximity to the own position 33, or to provide guidance to only the position closest to the own position 33.

[0014] For example, the controller 19 may display a first guidance screen on the HMI 13's display device as guidance regarding the parking position 31, presenting the parking position 31 to the user. Figure 3 is a schematic diagram of an example of the first guidance screen. The first guidance screen 40a includes an image 41 generated by imaging the area around the vehicle 1, an overhead image 42 generated by converting the image of the area around the vehicle 1, a message display area 43 where notifications such as visual messages are displayed, a parking start button 44, and an end button 45. When the user operates the parking start button 44 or the end button 45 displayed on the display device, the touch panel provided on the display device detects these operations. The overhead view image 42 displays an icon 42a representing the current position of the vehicle 1 and a target parking position mark 42b representing the parking position 31 superimposed on it. The message display area 43 of the first guidance screen 40a may display notifications, such as a visual message informing the user that the parking position 31 has been detected. When the end button 45 is pressed, the controller 19 stops the parking assistance control. The same applies when the end button 45 on the second guidance screen 40b, shown in Figure 8 and described later, is pressed. When the parking start button 44 is pressed, the controller 19 sets the parking position 31 as the target parking position and starts assisting the vehicle 1 in parking the vehicle at the target parking position. On the other hand, if there is no turning position 32 within a predetermined range 34 around the vehicle's own position 33, the user will not be shown any guidance regarding the parking position 31.

[0015] (operation) Figure 4 is a flowchart of the parking assistance method of the first embodiment. In step S1, the controller 19 obtains the pre-registered parking position 31 and turning position 32 from the storage device 19b. In step S2, the controller 19 detects its own position 33. In step S3, the controller 19 guides the user to the parking position 31 as a target parking position candidate based on the turning position 32 and its own position 33.

[0016] (Second Embodiment) In the second embodiment, the controller 19 pre-learns and registers objects present around the parking position 31 as "learned objects." When assisting with parking the vehicle 1, the controller detects the relative position of the parking position 31 to the vehicle 1 by comparing objects detected around the vehicle 1 with the learned objects. In the following description, objects detected around the vehicle 1 and compared with the learned objects during parking assistance may be referred to as "surrounding objects." Figures 5(a) and 5(b) are schematic diagrams illustrating an example of a method for detecting a parking position 31 using learned targets. When registering a parking position 31, targets present around the parking position 31 are extracted and stored (registered) in the storage device 19b as learned targets. For example, as shown in Figure 5(a), the vehicle 1 is driven manually along the parking path 30 to park at the parking position 31, and targets present around the vehicle 1 are detected by the external sensor 15 and stored as learned targets. The circular plots schematically represent learned targets. Figure 5(a) illustrates a parking path 30 that the vehicle 1 drives manually to the parking position 31 when registering the parking position 31. This path involves moving forward in the direction of the arrow 36 to approach the turning position 32, and then reversing to reach the parking position 31 after reaching the turning position 32. For example, the controller 19 may store the relative position of the learned object with respect to the parking position 31. The controller 19 can acquire the position of the learned object detected when its own vehicle 1 parks at the parking position 31 as the relative position of the learned object with respect to the parking position 31. The controller 19 may also store the coordinates of the learned object and the parking position 31 in the map coordinate system. The controller 19 stores learned object data related to the learned object in the storage device 19b. For example, the learned object data may include data representing the features of the learned object (hereinafter referred to as "feature data"), data on the relative position relationship between the parking position 31 and the learned object (hereinafter referred to as "relative position data"), and position data of the parking position 31 in the map coordinate system. As relative position data, for example, the controller 19 may store the relative position of the learned object with respect to the parking position 31. For example, the controller 19 can obtain the position of a learned object detected when its own vehicle 1 parks at the parking position 31 as the relative position of the learned object with respect to the parking position 31. The coordinates of the learned object and the parking position 31 in the map coordinate system may also be stored.

[0017] Refer to Figure 5(b). When assisting in parking the vehicle 1 at parking position 31, the controller 19 extracts objects around the vehicle 1 as surrounding objects using the external sensor 15. The triangular plot represents the surrounding objects. The controller 19 detects the parking position 31 that exists around the vehicle 1 by matching the learned objects with the surrounding objects and associating identical feature points. Based on the relative positional relationship between the surrounding objects detected during parking assistance and the vehicle 1, and the relative positional relationship between the learned objects associated with the surrounding objects and the parking position 31, the controller 19 calculates the relative position of the vehicle 1 with respect to the parking position 31. For example, the controller 19 calculates the position of the parking position 31 on a coordinate system (hereinafter referred to as the "vehicle coordinate system") based on the current position of the vehicle 1. Furthermore, if the coordinates of the learned target and the parking position 31 in the map coordinate system are stored in the storage device 19b, the coordinates of the 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 during parking assistance and the positions of the learned targets in the map coordinate system. The self-position 33 of the vehicle 1 in the map coordinate system may be determined based on the positions of the surrounding targets detected during parking assistance and the positions of the learned targets in the map coordinate system, and the relative position of the vehicle 1 with respect to the parking position 31 may be calculated from the difference between the coordinates of the vehicle 1 in the map coordinate system and the coordinates of the parking position 31. After that, the controller 19 calculates a target parking path 35 from the self-position 33 of the vehicle 1 to the parking position 31. When the parking position 31 is set as the target parking position, the controller 19 performs parking assistance control of the vehicle 1 based on the calculated target parking path 35.

[0018] Figure 6 is a block diagram of an example of the functional configuration of the parking assistance function by the controller in Figure 1. The HMI control unit 50 detects the user's operation to register the parking position 31. When the parking position 31 is registered, the HMI control unit 50 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 image conversion unit 52 converts the captured image into an overhead view image at predetermined intervals and accumulates the converted overhead view images along the vehicle 1's travel path to generate an ambient image, which is an image of the area surrounding the vehicle 1. The self-position calculation unit 53 calculates the self-position, which is the current position of the vehicle 1 on the map coordinate system, based on the positioning result of the vehicle 1 measured by the positioning device 11 using the satellite positioning system and autonomous navigation (for example, odometry such as dead reckoning) based on vehicle information output from the vehicle sensor 16.

[0019] For example, the self-position calculation unit 53 acquires the observed value Xo=(X coordinate, Y coordinate, azimuth angle (yaw angle)) of the vehicle 1's current position on the map coordinate system measured by the satellite positioning system from the positioning device 11. It also acquires positioning status information indicating the positioning status by the satellite positioning system. For example, the positioning status information may include the mode FIX_TYPE of the satellite positioning system's position information, the number of positioning satellites acquired NUM, the accuracy degradation rate DOP (Dilution Of Precision), which is an index value corresponding to the arrangement of the acquired positioning satellites, and a signal indicating whether or not satellite signals can be received. For example, the mode FIX_TYPE may be set to "NO FIX" indicating that position information cannot be obtained, "2D FIX" indicating that 2D information has been obtained, or "3D FIX" indicating that 3D information has been obtained. The self-position calculation unit 53 sets a satellite positioning system utilization flag Fs, which determines whether or not to use position information from the satellite positioning system, based on the shift position detected by the shift switch 14 and the positioning status information. When flag Fs = True, the self-position calculation unit 53 calculates the self-position of the vehicle 1 using the satellite positioning system and autonomous navigation, and when flag Fs = False, the self-position calculation unit 53 calculates the self-position of the vehicle 1 using only autonomous navigation. For example, the self-position calculation unit 53 may set the satellite positioning system utilization flag Fs to True if it is possible to receive satellite signals, the shift position is a forward driving position (e.g., drive range (D) or brake range (B)), the number of acquisitions NUM is greater than or equal to the number of acquisitions threshold thNUM, and the accuracy degradation rate DOP is less than the DOP threshold thDOP, and set it to False otherwise.

[0020] Furthermore, the self-position calculation unit 53 obtains the detected vehicle speed V, which is the velocity at the center of the rear axle of the vehicle 1, and the detected steering angle θ of the steering wheel from the vehicle sensor 16. Based on the detected vehicle speed V and steering angle θ, the self-position calculation unit 53 calculates the yaw rate γ of the vehicle 1. The self-position calculation unit 53 calculates the self-position of the vehicle 1 based on the detected and calculated values ​​obtained from the vehicle sensors 16, the observed value Xo and positioning status information obtained from the positioning device 11, and the satellite positioning system usage flag Fs. For example, the self-position calculation unit 53 may calculate the self-position of the vehicle 1 using an extended Kalman filter based on the rear axle-referenced geometric model described below. Currently, the status value of vehicle 1 is X_ = (X coordinate, Y coordinate, azimuth angle) T We define it as follows:

[0021]

number

[0022] In the above equation, the variables x, y, and θ are the previous state values ​​of the X coordinate, Y coordinate, and azimuth angle, respectively; ΔT is the calculation period of the Kalman filter; and the variable u is a vector (V,γ) whose elements are the vehicle speed V and the yaw rate γ. The error matrices R and Q are set as follows: Elements r1, r2, and r3 are the variances of the X error, Y error, and azimuth error of the satellite positioning system, respectively, and elements q1 and q2 are the variances of the vehicle speed and yaw rate errors. These elements r1, r2, r3, q1, and q2 are adjusted as appropriate according to the design. setting These are the adjustment parameters. In addition, the self-position calculation unit 53 sets the matrix C as follows according to the satellite positioning system usage flag Fs.

[0023]

number

[0024] The self-position calculation unit 53 calculates the variance S of the estimated value of the Kalman filter, the variance S_ of the predicted value, the Kalman gain K, and the self-position Xh of the vehicle 1 using the following equation. The self-position calculation unit 53 also calculates the norm Ns of the variance S and the norm Nk of the Kalman gain K.

[0025]

number

[0026] When the satellite positioning system usage flag Fs is True (meaning the satellite positioning system is used), the self-position Xh becomes X_ + K(Xo - CX_). In other words, the self-position Xh is calculated by correcting the state value X_ estimated by autonomous navigation with the observed value Xo from the satellite positioning system. On the other hand, if the satellite positioning system usage flag Fs is False (i.e., the satellite positioning system is not used), then matrix C becomes the zero matrix, and the self-position Xh becomes equal to X_. In other words, the self-position Xh is detected using only autonomous navigation without using the satellite positioning system. For example, if the shift position is a position other than the forward driving position, the self-position Xh is detected using only autonomous navigation without using the satellite positioning system. Furthermore, even when the satellite positioning system cannot detect its own position (for example, when satellite signals cannot be received, when the number of acquired satellites NUM is below a threshold, or when the accuracy degradation rate DOP is above a threshold), the self-position Xh=X_ is calculated using only the state value X_ estimated by autonomous navigation. In this case, the self-position is calculated based on the positioning results from past points in time when the satellite positioning system was able to detect its own position, and subsequent autonomous navigation.

[0027] 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 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 current position of the vehicle 1, obtained from the self-position calculation unit 53 in synchronization with the target detection, is output to the map generation unit 55 and the target parking position detection unit 57. When the map generation unit 55 receives a map generation command from the HMI control unit 50 (i.e., when the parking position 31 registration operation is performed), it generates learned target data and stores it in the storage device 19b as map data 56. For example, the map generation unit 55 receives target data and the current position of the vehicle 1 on the map coordinate system synchronized with the target data from the target detection unit 54. The map generation unit 55 acquires the position information of the parking position 31 in the map coordinate system. For example, the current position calculated by the self-position calculation unit 53 when the vehicle 1 is located at the parking position 31 may be acquired as the position information of the parking position 31. 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, and the position information of the parking position 31. The map generation unit 55 acquires feature data from the target data output from the target detection unit 54. These relative position data and feature data, along with the location data of the parking position 31, are stored in the storage device 19b as map data 56, along with the learned target data.

[0028] Refer to Figure 7. In addition to the learned target data, the map generation unit 55 stores the location information of the turning position 32, the information of the first parking azimuth angle Dp1 which is the azimuth angle of the parking position 31, and the information of the turning azimuth angle Dk which is the azimuth angle of the vehicle 1 at the turning position 32 as map data 56 in the storage device 19b. The map generation unit 55 may detect the azimuth angle of the vehicle 1 when the vehicle 1 is parked at the parking position 31 as the first parking azimuth angle Dp1. Furthermore, the map generation unit 55 may store in the storage device 19b the number of positioning satellites acquired NUM, the accuracy degradation rate DOP, and the estimated accuracy of the extended Kalman filter (e.g., norm Ns, Nk) when the vehicle 1 is manually driven to the parking position 31 in order to register the parking position 31. Furthermore, the first implementation form Similarly, the learned target data, the position information of the turning position 32, the first parking azimuth angle Dp1, the turning azimuth angle Dk, the number of targets NUM, the accuracy degradation rate DOP, and the estimated accuracy of the extended Kalman filter may be stored in an external storage device (e.g., a cloud computer) of the vehicle 1.

[0029] Refer to Figure 6. The parking assistance control unit 51 performs parking assistance control to assist in parking the vehicle 1 at a parking position 31 registered in the storage device 19b. The parking assistance control unit 51 can be set to switch between an "automatic start mode" which automatically starts searching for a parking position 31 in the vicinity of the vehicle 1, and a "manual start mode" which starts searching for a parking position 31 when a user operation (hereinafter sometimes referred to as "start operation") is performed to instruct the activation of the parking assistance control of the vehicle 1. For example, the start operation may be an operation of the parking switch 17 by the user. The parking assistance control unit 51 receives the vehicle's own position 33 from the self-position calculation unit 53 and obtains information on the previously registered turning position 32 from the storage device 19b. In automatic start mode, the parking assistance control unit 51 determines whether the turning position 32 is within a predetermined distance range 34 from the vehicle's own position 33. For example, the parking assistance control unit 51 determines whether the distance D between the vehicle's own position 33 and the turning position 32 is less than or equal to the distance threshold Dth. If the turning position 32 is within the predetermined distance range 34, the parking assistance control is automatically started. In manual start mode, when the parking assistance control unit 51 receives a start operation from the user, it determines whether the turning position 32 is within a predetermined distance range 34 from the vehicle's own position 33, and if the turning position 32 is within the predetermined distance range 34, the parking assistance control is started.

[0030] The parking assistance control unit 51 may change the distance threshold Dth according to the detection accuracy of the vehicle's own position. The parking assistance control unit 51 may also change the distance threshold Dth according to the detection accuracy of the vehicle's own position when it is manually driven to park at the parking position 31 in order to register the parking position 31 in advance, or it may change the distance threshold Dth according to the detection accuracy of the vehicle's own position when it performs parking assistance control to the parking position 31 after the parking position 31 has been registered. For example, the parking assistance control unit 51 may switch the distance threshold Dth according to the accuracy of self-position detection by the satellite positioning system. For example, the parking assistance control unit 51 may switch the distance threshold Dth according to whether or not self-position detection by the satellite positioning system is possible. For example, if the accuracy of self-position detection by the satellite positioning system is good, the parking assistance control unit 51 may set the distance threshold Dth to a first fixed value D1. If self-position detection by the satellite positioning system is not possible, the distance threshold Dth may be set to a second fixed value D2 which is greater than the first fixed value D1, or to a value selected by the user. For example, the parking assistance control unit 51 may determine that the detection accuracy is good if the mode FIX_TYPE of the position information of the satellite positioning system is "3D FIX", or if the number of acquisitions NUM is 6 or more and the accuracy degradation rate DOP is less than 3. For example, if the mode FIX_TYPE is "NO FIX" or the number of acquisitions NUM is 3 or less, the parking assistance control unit 51 may determine that self-position detection by the satellite positioning system is not possible. In all other cases, it may be determined that the satellite positioning system can detect its own position, but the detection accuracy is poor.

[0031] For example, the parking assistance control unit 51 may change the distance threshold Dth according to the accuracy of self-position detection by autonomous navigation. For example, the distance threshold Dth may be set larger when the accuracy of self-position detection by autonomous navigation is lower than when it is higher. For example, if the parking assistance control unit 51 determines that self-position detection by the satellite positioning system is possible but the detection accuracy is poor, it may set a larger distance threshold Dth when the detection error by autonomous navigation is large than when it is small. For example, the larger the detection error by autonomous navigation, the larger the distance threshold Dth may be set. For example, the parking assistance control unit 51 may set an additive value ΔD that increases as the detection error by autonomous navigation increases, and set the sum of the first fixed value D1 and the additive value ΔD as the distance threshold Dth = D1 + ΔD. The parking assistance control unit 51 may use the norm Ns of the variance S of the Kalman filter estimate or the norm Nk of the Kalman gain K as an indicator of the detection error by autonomous navigation.

[0032] When starting to search for the parking position 31, the parking support control unit 51 outputs a parking position calculation command to the target parking position detection unit 57. The HMI control unit 50 may display a second guidance screen for notifying that the controller 19 is searching for the parking position 31 existing around the host vehicle 1. FIG. 8 is a schematic diagram of an example of the second guidance screen. The second guidance screen 40b includes a captured image 41, an overhead image 42, a message display area 43, and an end button 45. Refer to FIG. 6. The target parking position detection unit 57 that has received the parking position calculation command receives the target data output from the target detection unit 54 as the target data of the surrounding targets, and synchronously receives the self-position of the host vehicle 1 in the map coordinate system. The target parking position detection unit 57 reads out the learned target data and the first parking azimuth angle Dp1 stored in the storage device 19b as the map data 56, matches the learned targets stored in the map data 56 with the surrounding targets, and associates the targets of the same feature points with each other. The target parking position detection unit 57 calculates the current relative position of the host vehicle 1 with respect to the parking position 31 based on the relative position relationship between the surrounding targets and the host vehicle 1 and the relative position relationship between the learned targets associated with the surrounding targets and the parking position 31. For example, the surrounding targets are represented as (x i , y i ), and the learned targets respectively associated with the surrounding targets (x i , y i ) are represented as (x mi , y mi ) (i = 1 to N). The target parking position detection unit 57 calculates the affine transformation matrix M affine1 by the following formula based on the least squares method.

[0033]

Equation

[0034] The target parking position detection unit 57 determines the position (targetx m , targety mBased on the following equation, the position (targetx, targety) of parking position 31 in the vehicle coordinate system is estimated.

[0035]

number

[0036] The target parking position detection unit 57 estimates the parking azimuth angle targetyaw of the parking position 31 in the vehicle coordinate system based on the first parking azimuth angle Dp1 stored in the map data 56 and the following equation. The parking azimuth angle targetyaw represents the relative azimuth angle of the parking azimuth angle of the parking position 31 with respect to the current azimuth angle of the vehicle 1.

[0037]

number

[0038] The target parking position detection unit 57 calculates the position of the parking position 31 on the map coordinate system based on the self-position of the vehicle 1 calculated by the self-position calculation unit 53 and the position of the parking position 31 on the vehicle coordinate system (targetx, targety). See Figure 9. Reference numeral 37 indicates the position of the parking position 31 on the map coordinate system calculated by the target parking position detection unit 57. In the following description, the position of the parking position 31 on the map coordinate system calculated by the target parking position detection unit 57 may be referred to as "detected position 37". The target parking position detection unit 57 calculates the parking azimuth angle of the parking position 31 on the map coordinate system based on the current azimuth angle of the vehicle 1 calculated by the self-position calculation unit 53 and the above-mentioned parking azimuth angle targetyaw. In the following description, the parking azimuth angle of the parking position 31 on the map coordinate system calculated by the target parking position detection unit 57 may be referred to as the "second parking azimuth angle Dp2".

[0039] Here, as shown in Figure 9, a detection error may occur between the detected position 37 and the second parking azimuth angle Dp2 calculated by the target parking position detection unit 57 and the parking position 31 and the first parking azimuth angle Dp1 stored in the map data 56. For example, when assisting the parking of the vehicle 1 at the registered parking position 31, it is assumed that the vehicle 1 moves forward in the direction of arrow 38 to approach the turning position 39, and after reaching the turning position 39, moves backward to reach the parking position 31. On the other hand, when registering the parking position 31, it is assumed that the vehicle moves forward in the direction of arrow 36 to approach the turning position 32, as shown in Figures 5(a) and 7. Thus, if the direction in which the vehicle 1 moves forward to the turning position when registering the parking position 31 and the direction in which the vehicle 1 moves forward to the turning position when assisting in parking the vehicle 1 at the registered parking position 31 are opposite directions, detection errors may occur between the detected position 37 calculated by the target parking position detection unit 57 and the parking position 31 stored in the map data 56, or between the second parking azimuth angle Dp2 and the first parking azimuth angle Dp1. Furthermore, detection errors may also occur due to positioning errors in the positioning device 11 and the self-position calculation unit 53, or due to matching errors between learned targets and surrounding targets.

[0040] Therefore, the parking support control unit 51 determines the appropriateness of the relative position of the parking position 31 calculated by the target parking position detection unit 57 based on the relative position of the parking position 31 with respect to the vehicle 1 calculated by the target parking position detection unit 57 (i.e., the position of the parking position 31 on the vehicle coordinate system (targetx, targety)) and the azimuth angle difference Δθ between the first parking azimuth angle Dp1 and the second parking azimuth angle Dp2. For example, the parking support control unit 51 determines that the relative position of the parking position 31 calculated by the target parking position detection unit 57 is appropriate if the relative position of the parking position 31 calculated by the target parking position detection unit 57 is within a predetermined distance range of the vehicle 1 and the azimuth angle difference Δθ is less than or equal to a threshold. Conversely, the parking support control unit 51 determines that the relative position of the parking position 31 calculated by the target parking position detection unit 57 is not appropriate if the relative position of the parking position 31 calculated by the target parking position detection unit 57 is not within a predetermined distance range of the vehicle 1 or if the azimuth angle difference Δθ is greater than a threshold. The parking assistance control unit 51 may determine that the relative position of the parking position 31 calculated by the target parking position detection unit 57 is appropriate if the difference in azimuth angle between the current azimuth angle of the vehicle 1 and the turning azimuth angle Dk stored in the memory device 19b is less than or equal to a threshold, and may determine that it is not appropriate if it is greater than the threshold.

[0041] The relative parking position 31 calculated by the target parking position detection unit 57 position If the HMI control unit 50 determines that the parking position is appropriate, it may display the first guidance screen 40a shown in Figure 3 on the display device of the HMI 13. On the other hand, if the HMI control unit 50 determines that the relative position of the parking position 31 calculated by the target parking position detection unit 57 is not appropriate, it may display an error message on the HMI 13 indicating, for example, that the parking position could not be found, and terminate the parking assistance control. When the parking start button 44 is pressed on the first guidance screen 40a, the parking position 31 is set as the target parking position, and assistance for parking the vehicle 1 at the target parking position begins. The target trajectory generation unit 59 calculates the target parking path from the vehicle 1's current position to the parking position 31. The target trajectory generation unit 59 calculates the 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 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.

[0042] Figure 10 is a flowchart of the parking assistance method of the second embodiment. In step S10, the controller 19 obtains pre-stored learned target data, the first parking azimuth angle Dp1, and the turning position 32 from the storage device 19b. In step S11, the controller 19 detects its own position 33. In step S12, the controller 19 determines whether the turning position 32 is within a predetermined distance range 34 from its own position 33. If the turning position 32 is within the predetermined distance range 34 (step S12:Y), the process proceeds to step S13. If the turning position 32 is not within the predetermined distance range 34 (step S12:N), the process ends without displaying guidance for the parking position 31. In this case, parking assistance for the vehicle 1 to the target parking position is not performed. In step S13, the controller 19 detects surrounding targets. In step S14, the controller 19 calculates the relative position of the parking position 31 with respect to the vehicle 1 and the second parking azimuth angle Dp2.

[0043] In step S15, the controller 19 determines whether the relative position of the parking position 31 is within a predetermined distance range of the vehicle 1, and whether the azimuth angle difference Δθ between the first parking azimuth angle Dp1 and the second parking azimuth angle Dp2 is less than or equal to a threshold. If the relative position of the parking position 31 is within a predetermined distance range of the vehicle 1 and the azimuth angle difference Δθ is less than or equal to the threshold (step S15:Y), the process proceeds to step S16. If the relative position of the parking position 31 is not within a predetermined distance range of the vehicle 1, or if the azimuth angle difference Δθ is greater than the threshold (step S15:N), the process ends without displaying guidance for the parking position 31. In this case, parking assistance for the vehicle 1 to the target parking position is not performed. In step S16, the controller 19 displays the first guidance screen 40a on the display device of the HMI 13. The controller 19 calculates the target parking route from the current position of the vehicle 1 to the parking position 31. In step S17, the controller 19 performs parking assistance control of the vehicle 1 based on the calculated target parking route. The process then ends.

[0044] (Effects of the embodiment) (1) The controller 19 retrieves information on the parking position when the vehicle was parked and information on the turning position when the vehicle turned around after being parked, from a storage device that was stored in advance when the vehicle was parked. The controller 19 then detects the current position of the vehicle 1, and based on the turning position and the controller 1, guides the user of the vehicle 1 to a parking position as a target parking position candidate. This allows the user to be automatically guided to a parking position when the vehicle 1 approaches a pre-registered parking position. As a result, when the user is presented with guidance on a pre-stored target position, the user's operation to select a parking position can be reduced. (2) The controller 19 may guide the vehicle to a parking position if the distance between its own position and the turning position is less than or equal to a distance threshold. This allows the controller to determine whether the vehicle 1 is approaching a pre-registered parking position.

[0045] (3) The controller 19 may change the distance threshold according to the accuracy of its own position detection. This makes it possible to detect a pre-registered parking position even in places where the accuracy of its own position detection is low. (4) The controller 19 may detect its own position using a satellite positioning system and set a distance threshold according to at least one of the number of positioning satellites acquired or their arrangement. This allows the distance threshold to be changed according to the accuracy of the detection of the own position when detecting its own position using a satellite positioning system. (5) The controller 19 may increase the distance threshold when the accuracy of self-position detection by autonomous navigation is lower than when it is high. This allows the distance threshold to be changed according to the accuracy of self-position detection when self-position is detected by autonomous navigation.

[0046] (6) The controller 19 may retrieve learned target data from a storage device that stores data representing the relative positional relationship between the parking position and targets present around the parking position as learned target data, detect the positions of surrounding targets which are targets present around the vehicle 1, calculate the relative positional relationship between the parking position and the controller based on the learned target data and the positions of the surrounding targets, calculate a driving trajectory from the controller to the parking position based on the calculated relative positional relationship, and when the parking position is set as the target parking position, assist in parking the vehicle 1 to the target parking position based on the driving trajectory. This allows the user to use parking assistance control that assists in parking the vehicle 1 to a pre-registered parking position. (7) The controller 19 may obtain parking azimuth information from a storage device that has previously stored information on the azimuth angle of the vehicle when parked in the parking position, estimate the relative azimuth angle of the parking azimuth angle with respect to the current azimuth angle of the vehicle 1 based on the learned target data, the positions of surrounding targets, and the parking azimuth angle, detect the current azimuth angle of the vehicle 1, and determine whether or not to assist in parking the vehicle 1 at the target parking position based on the difference between the parking azimuth angle estimated based on the current azimuth and relative azimuth angle and the parking azimuth angle obtained from the storage device. This makes it possible to determine whether or not the relative position of the parking position calculated based on the learned target data and the positions of surrounding targets is appropriate.

[0047] (8) The controller 19 may obtain information on the turning azimuth angle, which is the azimuth angle of the vehicle at the turning position, from a storage device that has previously stored this information, detect the current azimuth angle of the vehicle 1, and determine whether or not to assist in parking the vehicle 1 at the target parking position based on the difference between the current azimuth angle and the turning azimuth angle. This makes it possible to determine whether or not the relative position of the parking position calculated based on the learned target data and the positions of surrounding targets is appropriate.

[0048] All examples and conditional terms set forth herein are intended for educational purposes to help the reader understand the concepts given by the inventors for the advancement of the invention and the art, and should be interpreted without limitation to the examples and conditions specifically described herein, as well as the configuration of examples relating to demonstrating the superiority and inferiority of the invention. Although embodiments of the invention are described in detail, it should be understood that various changes, substitutions, and modifications are possible without departing from the spirit and scope of the invention. [Explanation of Symbols]

[0049] 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. The system retrieves the parking position information and the turning position information, which is the position where the vehicle turned around after being parked, from a storage device that was previously stored when the vehicle was parked. The vehicle detects its own current position, Based on the aforementioned turning position and the vehicle's own position, the user of the vehicle is guided to the parking position as a candidate target parking position. A parking assistance method characterized by the following features.

2. The parking assistance method according to claim 1, characterized in that the parking position is guided when the distance between the self-position and the turning position is less than or equal to a distance threshold.

3. The parking assistance method according to claim 2, characterized in that the distance threshold is changed according to the accuracy of detecting the self-position.

4. The parking assistance method according to claim 3, characterized in that the self-position is detected by a satellite positioning system and the distance threshold is set according to at least one of the number of positioning satellites acquired or their arrangement.

5. The parking assistance method according to claim 3, characterized in that the distance threshold is set to be larger when the accuracy of detecting the self-position by autonomous navigation is lower than when it is high.

6. From the storage device that stores data representing the relative positional relationship between the parking position and the targets present around the parking position as learned target data, the learned target data is retrieved. The position of surrounding targets, which are objects present around the vehicle, is detected. Based on the learned target data and the positions of the surrounding targets, the relative positional relationship between the parking position and the self-position is calculated. A parking assistance method according to any one of claims 1 to 5, characterized in that, based on the calculated relative positional relationship, a driving trajectory from the vehicle's own position to the parking position is calculated, and when the parking position is set as the target parking position, the vehicle assists in parking the vehicle at the target parking position based on the driving trajectory.

7. The system retrieves the parking azimuth angle information, which is the azimuth angle of the vehicle when parked in the aforementioned parking position, from the storage device that has previously stored the parking azimuth angle information, estimates the relative azimuth angle of the parking azimuth angle to the current azimuth angle of the vehicle, based on the learned target data, the positions of the surrounding targets, and the parking azimuth angle, The current azimuth angle of the vehicle is detected, Based on the difference between the parking azimuth angle estimated based on the current azimuth angle and the relative azimuth angle, and the parking azimuth angle obtained from the storage device, it is determined whether or not to assist in parking the vehicle at the target parking position. The parking assistance method described in feature 6.

8. From the storage device that has previously stored information on the turning azimuth angle, which is the azimuth angle of the vehicle at the turning position, the information on the turning azimuth angle is obtained. The current azimuth angle of the vehicle is detected, Based on the difference between the current azimuth angle and the turning azimuth angle, it is determined whether or not to assist in parking the vehicle at the target parking position. The parking assistance method described in feature 6.

9. A process to obtain information on the parking position when the vehicle was parked, and information on the turning position, which is the position where the vehicle turned around after being parked, from a storage device that was previously stored when the vehicle was parked. The process of detecting the vehicle's current position, and A process to guide the user of the vehicle to the parking position as a target parking position candidate based on the aforementioned turning position and the vehicle's own position, A parking assistance device characterized by having a controller that performs the following.

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