Parking assistance method and parking assistance device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NISSAN MOTOR CO LTD
- Filing Date
- 2023-01-27
- Publication Date
- 2026-06-30
Smart Images
Figure 0007882353000006 
Figure 0007882353000007 
Figure 0007882353000008
Abstract
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 project] [Problems that the invention aims to solve]
[0004] When presenting a user with guidance for a pre-stored parking target location, if the parking target location is in a place where the accuracy of detecting the vehicle's own position is low, there is a risk that the system may not be able to determine that the vehicle has approached the parking target location. The present invention aims to make it easier for users to determine when their vehicle is approaching a pre-stored parking target location, even in locations where the accuracy of detecting the vehicle's own position is low, 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 point, which is the point where the vehicle turned around when it was parked, from a storage device that was previously stored when the vehicle was parked. The method detects the vehicle's current position, sets a threshold according to the accuracy of the detection of the vehicle's position, and guides the user of the vehicle to the parking position as a target parking position candidate if the distance between the turning point and the vehicle's position is less than or equal to the threshold. [Effects of the Invention]
[0006] According to the present invention, when presenting a pre-stored parking target location to the user, it becomes easier to determine when the vehicle is approaching the parking target location, even in locations where the accuracy of detecting the vehicle's own position is low. 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 an example of the second guidance screen. [Figure 8] This is a flowchart of the parking assistance method according to the second embodiment. [Figure 9] This is a flowchart illustrating an example of how to set thresholds. [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 distance measuring 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 assistance control by the parking assistance device 10.
[0011] The controller 19 is an electronic control unit that performs parking assistance control of the host vehicle 1. The controller 19 includes a processor 19a and peripheral components such as a storage device 19b. The processor 19a may be, for example, a CPU or an MPU. The storage device 19b may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The functions of the controller 19 described below are realized, for example, 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's 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 according 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 according to a control signal from the controller 19. The brake actuator 21c operates the braking device according 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 (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. Here, "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 its own position 33. The controller 19 sets a threshold Dth according to the detection accuracy of the own position 33 by the positioning device 11. For example, the controller 19 may set a larger threshold Dth when the detection accuracy is low than when it is high. For example, the lower the detection accuracy, the larger the threshold Dth may be set.
[0014] The controller 19 presents the user with guidance regarding parking positions 31 as target parking position candidates when the distance D between its own position 33 and the turning position 32 is less than or equal to the threshold Dth. For example, the controller 19 may display a first guidance screen that presents parking positions 31 to the user on the display device of the HMI 13 as guidance regarding parking positions 31. If there are multiple parking positions 31 that satisfy the above conditions, the controller 19 may guide the user with all of the parking positions that satisfy the conditions, guide them in order of proximity to the user's own position 33, or guide them with only the closest one to the user's own position 33. 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 capturing images of 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 a parking position 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 7 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 at the target parking position. On the other hand, if the distance D between the user's own position 33 and the turning position 32 is longer than the threshold Dth, the user will not be shown guidance regarding the parking position 31.
[0015] The controller 19 may also determine whether or not to provide guidance regarding the parking position 31 depending on whether the distance between its own position 33 and the parking position 31 is less than or equal to a threshold Dth. Alternatively, the controller 19 may determine whether or not to provide guidance regarding the parking position 31 depending on whether the distance between its own position 33 and any point on the line segment connecting the parking position 31 and the turning position 32 is less than or equal to a threshold Dth. For example, the controller 19 may determine whether or not to provide guidance regarding the parking position 31 depending on whether the distance between its own position 33 and the midpoint between the parking position 31 and the turning position 32 is less than or equal to a threshold Dth.
[0016] (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 sets a threshold Dth according to the detection accuracy of its own position 33. In step S4, the controller 19 determines whether the distance D between its own position 33 and the turning position 32 is less than or equal to the threshold Dth. If the distance D is not less than or equal to the threshold Dth (step S4:N), the process ends. If the distance D is less than or equal to the threshold Dth (step S4:Y), the process proceeds to step S5. In step S5, 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. The process then ends.
[0017] (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 and parked 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 plot schematically represents learned targets. 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.
[0018] 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. The controller 19 performs parking assistance control of the vehicle 1 based on the calculated target parking path 35.
[0019] 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.
[0020] 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.
[0021] 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:
[0022]
number
[0023] 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.
[0024]
number
[0025] 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.
[0026]
number
[0027] 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. This is because, in cases other than forward driving, the vehicle is moving at a low speed or is stopped, so the error in the self-position determined by the satellite positioning system becomes larger than the distance traveled, making it impossible to accurately determine the self-position. Therefore, the satellite positioning system may be used only when driving at a predetermined speed or higher, and the self-position Xh may be detected using only autonomous navigation without using the satellite positioning system when driving at a speed below the predetermined speed. 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.
[0028] 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.
[0029] In addition to the learned target data mentioned above, the map generation unit 55 stores the location information of the turning position 32 as map data 56 in the storage device 19b. Furthermore, in order to register the parking position 31, the map generation unit 55 stores 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. Furthermore, the first implementation form Similarly, the learned target data, the location information of the turning position 32, 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.
[0030] 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 switched between an "automatic start mode" that automatically starts searching for a parking position 31 around the vehicle 1 and a "manual start mode" that 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 also 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 distance D between the vehicle's own position 33 and the turning position 32 is less than or equal to the threshold Dth. If the distance D is less than or equal to the threshold Dth, the parking assistance control is automatically started. In manual start mode, when the parking assist control unit 51 receives a start operation from the user, it determines whether the distance D is less than or equal to the threshold Dth, and starts parking assist control if the distance D is less than or equal to the threshold Dth.
[0031] The parking assistance control unit 51 changes the threshold Dth according to the detection accuracy of the vehicle's own position. The parking assistance control unit 51 may change the threshold Dth according to the detection accuracy of the vehicle's own position when it is parked at the parking position 31 by manual driving in order to register the parking position 31 in advance, or it may change the 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 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 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 threshold Dth to a first fixed value D1. If self-position detection by the satellite positioning system is not possible, the 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.
[0032] For example, the parking assistance control unit 51 may change the threshold Dth according to the accuracy of self-position detection by autonomous navigation. For example, the 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 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 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 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.
[0033] 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. 7 is a schematic diagram of an example of the second guidance screen. The second guidance screen 40b includes an imaging image 41, an overhead image 42, a message display area 43, and an end button 45. Referring to FIG. 6, 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 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 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.
[0034] [Number]
[0035] The target parking position detection unit 57 determines the position (targetx m , targety<Based on the following equation, the position (targetx, targety) of the parking position 31 in the vehicle coordinate system is estimated.
[0036]
number
[0037] When the target parking position detection unit 57 successfully estimates the position of the parking position 31 on the vehicle coordinate system (i.e., when the learned target and surrounding target are successfully matched), the HMI control unit 50 displays the first guidance screen 40a shown in Figure 3 on the display device of the HMI 13. 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.
[0038] Figure 8 is a flowchart of the parking assistance method of the second embodiment. In step S10, the controller 19 acquires pre-stored learned target data and 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 sets a threshold Dth according to the detection accuracy of its own position 33. Figure 9 is a flowchart of an example of how to set the threshold Dth. In step S20, the controller 19 determines whether the accuracy of self-position detection by the satellite positioning system is good or not. If the detection accuracy is good (step S20:Y), the process proceeds to step S21. If the detection accuracy is not good (step S20:N), the process proceeds to step S22. In step S21, the controller 19 sets the threshold Dth to the first fixed value D1. After that, the process ends.
[0039] In step S22, the controller 19 determines whether or not it is possible to detect its own position using the satellite positioning system. If it is possible to detect its own position (step S22:Y), the controller 19 determines that the accuracy of the satellite positioning system's detection of its own position is poor, and the process proceeds to step S23. If it is not possible to detect its own position (step S22:N), the process proceeds to step S25. In step S23, the controller 19 sets an added value ΔD according to the accuracy of self-position detection by autonomous navigation. In step S24, the controller 19 sets the sum of the first fixed value D1 and the added value ΔD as the threshold Dth = D1 + ΔD. The process then ends. In step S25, the controller 19 sets a second fixed value D2 that is greater than the first fixed value D1, or a value selected by the user, as the threshold Dth. The process then ends.
[0040] Refer to Figure 8. In step S13, the controller 19 determines whether the distance D between its own position 33 and the turning position 32 is less than or equal to the threshold Dth. If the distance D is not less than or equal to the threshold Dth (step S13: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. If the distance D is less than or equal to the threshold Dth (step S13:Y), the process proceeds to step S14. In step S14, the controller 19 detects surrounding objects. In step S15, the controller 19 calculates the relative position of the parking position 31 to the vehicle 1 and displays the first guidance screen 40a on the HMI 13 display device. In step S16, the controller 19 calculates the target parking route from the vehicle 1's current position 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.
[0041] (Effects of the embodiment) (1) The controller 19 obtains information on the parking position when the vehicle was parked and information on the turning point where the vehicle turned around when it was parked from a storage device that was stored in advance when the vehicle was parked, detects the current position of the vehicle 1, sets a threshold according to the accuracy of the detection of the vehicle's position, and guides the user of the vehicle 1 to the parking position as a target parking position candidate when the distance between the turning point and the vehicle's position is less than or equal to the threshold. This makes it easier to determine that the vehicle 1 is approaching the parking target position even in places where the accuracy of detecting the vehicle 1's position is low when presenting guidance to the user for a pre-stored parking target position. (2) The controller 19 may detect its own position using the satellite positioning system and switch the threshold depending on whether or not the satellite positioning system can detect its own position. This allows the threshold to be changed according to the accuracy of the detection of the own position when the satellite positioning system detects its own position.
[0042] (3) The controller 19 may detect its own position using a satellite positioning system and set a threshold according to the number of positioning satellites acquired. This allows the 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. (4) The controller 19 may detect its own position using a satellite positioning system and set a threshold value according to an index value based on the arrangement of the acquired positioning satellites. This allows the 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) If the controller 19 is unable to detect its own position using the satellite positioning system, it may detect its own position based on the detection result at the time when it was able to detect its own position using the satellite positioning system and autonomous navigation. This allows the system to continue detecting its own position even if it loses the ability to do so using satellite positioning systems.
[0043] (6) The controller 19 does not need to perform self-position detection by the satellite positioning system when the shift position of the vehicle 1 is in a position other than the forward driving position. This suppresses the decrease in the accuracy of the satellite positioning system's detection of the vehicle 1's azimuth angle when the vehicle 1 is not continuously driving forward. (7) The controller 19 may set a higher threshold when the accuracy of self-position detection by autonomous navigation is lower than when it is high. This allows the threshold to be changed according to the accuracy of self-position detection when self-position is detected by autonomous navigation.
[0044] (8) The controller 19 retrieves 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, detects the positions of surrounding targets which are targets present around the vehicle 1, calculates the relative positional relationship between the parking position and the controller based on the learned target data and the positions of the surrounding targets, calculates 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, the controller 19 may assist in parking the vehicle 1 at 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 at a pre-registered target parking position.
[0045] 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]
[0046] 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 obtains information about the parking position at the time of parking, and information about the turning point, which is the point where the vehicle turned around when it was parked, from a storage device that was previously stored when the vehicle was parked. The vehicle detects its own current position, A threshold is set according to the self-position detection accuracy, If the distance between the turning point and the vehicle's own position is less than or equal to the threshold, the vehicle's user is guided to the parking position as a candidate target parking position. A parking assistance method characterized by the following features.
2. The satellite positioning system detects the self-position, The parking assistance method according to claim 1, characterized in that the threshold is switched depending on whether or not the satellite positioning system can detect the self-position.
3. The satellite positioning system detects the self-position, The parking assistance method according to claim 1, characterized in that the threshold is set according to the number of positioning satellites acquired.
4. The satellite positioning system detects the self-position, The parking assistance method according to claim 1, characterized in that the threshold is set according to an index value based on the arrangement status of the acquired positioning satellites.
5. The parking assistance method according to claim 1, characterized in that, if the satellite positioning system cannot detect the self-position, the self-position is detected based on the detection result at the time the satellite positioning system was able to detect the self-position and autonomous navigation.
6. The parking assistance method according to any one of claims 2 to 5, characterized in that the satellite positioning system does not detect the vehicle's own position when the vehicle's shift position is in a position other than the forward driving position.
7. The parking assistance method according to claim 5, characterized in that the threshold is set to be larger when the accuracy of detecting the self-position by the autonomous navigation is lower than when it is high.
8. 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. Based on the calculated relative positional relationship, the driving trajectory from the self-position to the parking position is calculated. When the aforementioned parking position is set as the target parking position, the system assists in parking the vehicle at the target parking position based on the driving trajectory. The parking assistance method according to any one of claims 1 to 5.
9. A process to obtain information on the parking position when parking was performed and information on the turning point, which is the point where the vehicle turned around when it was parked, from a storage device that was previously stored when parking, the parking position and the turning point information. The process of detecting the vehicle's current position, and A process to set a threshold according to the self-position detection accuracy, A process to guide the user of the vehicle to the parking position as a target parking position candidate when the distance between the turning point and the vehicle's own position is less than or equal to the threshold, A parking assistance device characterized by having a controller that performs the following.