Parking assistance method and parking assistance device

Abstract

This parking assistance method is configured such that a first image is generated by imaging the periphery of a parking space using a first camera installed in the parking space (S1), the first image is transmitted to a vehicle (S2), a second image is generated by imaging the periphery of the vehicle using a second camera mounted on the vehicle (S3), and parking assistance for parking the vehicle at a target parking position within the parking space is executed on the basis of the first image and the second image (S4).

Description

Parking assistance method and parking assistance device

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

[0002] The parking assistance device described in Patent Document 1 below provides parking assistance for a vehicle based on position information of the vehicle acquired by the vehicle and image information captured by an infrastructure camera fixed to a parking facility.

[0003] JP 2015-74321 A

[0004] However, in the parking assistance described in Patent Document 1, if the infrastructure camera cannot capture an image of the entire vehicle body, there is a risk that the accuracy of the parking position will decrease. An object of the present invention is to improve the accuracy of the parking position in parking assistance using a camera installed in a parking space.

[0005] In one aspect of the parking assistance method of the present invention, a first image is generated by photographing the surroundings of the parking space with a first camera installed in the parking space, the first image is transmitted to the vehicle, a second image is generated by photographing the surroundings of the vehicle with a second camera mounted on the vehicle, and parking assistance is performed to park the vehicle at a target parking position within the parking space based on the first image and the second image.

[0006] According to the present invention, the accuracy of the parking position can be improved in parking assistance using a camera installed in a parking space. The objects and advantages of the present invention are realized and achieved by using the elements and combinations set forth in the claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as claimed.

[0007] FIG. 1 is a diagram showing an example of a schematic configuration of a parking assistance system according to an embodiment. FIG. 2 is an explanatory diagram of an example of a parking assistance method according to an embodiment. FIG. 3 is a flowchart of an example of a parking assistance method according to an embodiment. FIG. 4 is a block diagram of an example of a functional configuration of the controller of FIG. 1 in a second embodiment. (a) and (b) are explanatory diagrams of an example of a method for detecting the rear end position of a vehicle. (b) are explanatory diagrams of an example of a parking assistance method from a parking start position to an intermediate position. (b) are explanatory diagrams of an example of a parking assistance method from an intermediate position to a target parking position. (a) and (b) are explanatory diagrams of an example of a method for detecting the front end position of a vehicle.

[0008] (First embodiment) (Configuration) Fig. 1 is a diagram showing an example of the schematic configuration of a parking assistance system according to an embodiment. The parking assistance system 1 assists in parking a vehicle 3 at a target parking position in a parking space 2. For example, parking assistance by the parking assistance system 1 performs parking control such that the vehicle 3 automatically travels from the current position of the vehicle 3 to the target parking position along a target parking path.

[0009] Here, parking control for automatically driving the vehicle 3 along a target parking path to a target parking position refers to control for automatically driving all or part of the vehicle 3 along the target parking path by controlling the steering angle, driving force, and braking force of the vehicle 3. Furthermore, for example, parking assistance by the parking assistance system 1 may include driving assistance control for assisting the user who is parking the vehicle 3 by displaying the target parking path and the current position of the vehicle 3 on a display device that is visible to the user (e.g., a passenger such as the driver) of the vehicle 3.

[0010] The parking assistance system 1 includes a ground device 20 installed in the parking space 2 and a parking assistance device 30 mounted on the vehicle 3. The ground device 20 includes a first camera 21, a communication device 22, and a controller 23. The first camera 21 generates a first image by capturing an image of the surroundings of the parking space 2. The communication device 22 performs wireless communication with the vehicle 3 (specifically, performs wireless communication with a communication device 33 of the vehicle 3, which will be described later). The communication method used by the communication device 22 may be, for example, wireless communication via a public mobile phone network, vehicle-to-vehicle communication, road-to-vehicle communication, or satellite communication.

[0011] The controller 23 is an electronic control unit (ECU) that processes various types of information for parking assistance by the parking assistance system 1. The controller 23 includes a processor 23a and peripheral components such as a storage device 23b. The processor 23a may be, for example, a central processing unit (CPU) or a micro-processing unit (MPU). The storage device 23b may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 23b may include memories such as a read-only memory (ROM) and a random access memory (RAM) used as main storage devices, as well as registers and cache memories. The functions of the controller 23 described below are realized, for example, by the processor 23a executing computer programs stored in the storage device 23b.

[0012] The controller 23 may be formed of dedicated hardware for executing each of the information processes described below. For example, the controller 23 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 23 may include a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0013] For example, the controller 23 may transmit the first image generated by the first camera 21 to the parking assistance device 30 of the vehicle 3. Furthermore, for example, the controller 23 may calculate information on the relative position of the vehicle 3 (e.g., the rear end position of the vehicle 3) with respect to the target parking position based on the position of the vehicle 3 in the first image generated by the first camera 21, and transmit the information to the parking assistance device 30.

[0014] The parking assistance device 30 includes an object sensor 31, a vehicle sensor 32, a communication device 33, an HMI (Human Machine Interface) 34, a steering actuator (steering ACTR) 35a, an accelerator actuator (accelerator ACTR) 35b, a brake actuator (brake ACTR) 35c, and a controller 36. The object sensor 31 detects objects within a predetermined distance range from the vehicle 3. The object sensor 31 detects the environment around the vehicle 3, such as the relative position between the vehicle 3 and objects present around the vehicle 3, the distance between the vehicle 3 and the objects, and the direction in which the objects are present.

[0015] For example, the object sensor 31 may include a second camera 37 that captures an image of the environment surrounding the vehicle 3. The second camera 37 may include a front camera that captures an image in front of the vehicle 3 or a rear camera that captures an image behind the vehicle 3. The object sensor 31 may include a distance measuring device such as a laser range finder, radar, LiDAR (Light Detection and Ranging), or sonar. The vehicle sensor 32 detects various information (vehicle information) of the vehicle 3. For example, the vehicle sensor 32 may include a vehicle speed sensor that detects the traveling speed of the vehicle 3, a three-axis acceleration sensor that detects the acceleration (including deceleration) in three axial directions of the vehicle 3, and a sensor that detects the steering angle of the steering wheel and the steering angle of the steered wheels.

[0016] The communication device 33 performs wireless communication with the communication device 22 of the ground device 20. The communication method used by the communication device 33 may be, for example, wireless communication via a public mobile phone network, vehicle-to-vehicle communication, road-to-vehicle communication, or satellite communication. The HMI 34 is an interface device that exchanges information between the parking assistance device 30 and the user of the vehicle 3. For example, the HMI 34 may include a display device that is visible to the user as an interface that presents visual information to the user. The HMI 34 may also include a speaker or a buzzer as an interface that presents auditory information to the user. The HMI 34 may also include an interface (such as a touch panel, button, switch, lever, dial, or keyboard) that accepts operational input from the user.

[0017] The controller 36 is an electronic control unit that performs the parking control and driving assistance control described above as parking assistance by the parking assistance system 1. The controller 36 includes a processor 36a and peripheral components such as a storage device 36b. The processor 36a may be, for example, a CPU or an MPU. The storage device 36b may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 36b may include memories such as ROM and RAM used as main storage devices, as well as registers and cache memories. The functions of the controller 36 described below are realized, for example, by the processor 36a executing computer programs stored in the storage device 36b.

[0018] The controller 36 may be formed of dedicated hardware for executing the information processing described below. For example, the controller 36 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 36 may include a PLD such as an FPGA.

[0019] The steering actuator 35a controls the steering direction and steering amount of the steering mechanism of the vehicle 3 in response to a control signal from the controller 36. The accelerator actuator 35b controls the accelerator opening of the drive device, which is the engine or drive motor, in response to a control signal from the controller 36. The brake actuator 35c activates the braking device in response to a control signal from the controller 36.

[0020] 2, the parking assistance function of the parking assistance system 1 will be described. The parking assistance function of the parking assistance system 1 calculates the relative positional relationship between the current position of the vehicle 3 and a target parking position set in the parking space 2. For example, the vehicle 3 parking in the parking space 2 may be photographed by the first camera 21 of the ground device 20, and the relative position of the vehicle 3 with respect to the target parking position may be detected based on the first image photographed by the first camera 21.

[0021] For example, when the vehicle 3 backs up to park in the parking space 2, the position Ptr of the rear end of the vehicle body of the vehicle 3 when parked in the parking space 2 may be set as the target parking position (hereinafter may be referred to as the "target rear end position Ptr"). As the relative position of the vehicle 3, the relative position Pr of the current rear end of the vehicle body of the vehicle 3 (hereinafter may be referred to as the "vehicle rear end position Pr") to the target rear end position Ptr may be calculated. Figure 2 shows an example of when the vehicle 3 backs up to park in the parking space 2.

[0022] When the vehicle 3 moves forward to park in the parking space 2, the position Ptf of the front end of the body of the vehicle 3 when parked in the parking space 2 may be set as the target parking position (hereinafter, may be referred to as the "target front end position Ptf"). As the relative position of the vehicle 3, the relative position of the current position Pf of the front end of the body of the vehicle 3 (hereinafter, may be referred to as the "vehicle front end position Pf") with respect to the target front end position Ptf may be calculated.

[0023] For example, the first camera 21 may be installed at one of the two ends Ef and Er in the front-to-rear direction of the parking space 2, on the other end Er side opposite the one end Ef where the vehicle 3 parks in the parking space 2, so as to be able to photograph the vehicle 3 entering the parking space 2 to park. The photographing direction (optical axis direction) of the first camera 21 may be set to photograph the direction from the other end Er side toward the one end Ef side.

[0024] The controller 36 calculates a target parking path Tr from the current position of the vehicle 3 to the target parking position based on the relative positional relationship. The controller 36 executes parking assistance to park the vehicle 3 at the target parking position based on the target parking path Tr. For example, the controller 36 performs parking control to drive the vehicle 3 along the target parking path Tr to the target parking position. Specifically, the controller 36 controls the steering actuator 35 a, accelerator actuator 35 b, and brake actuator 35 c so that the vehicle 3 drives to the target parking position and stops. Furthermore, for example, the controller 36 displays the target parking path Tr and the current position of the vehicle 3 on the HMI 34 to assist the user in parking the vehicle 3.

[0025] When assisting parking of the vehicle 3 based on the first image generated by the first camera 21 in this way, there is a risk that the accuracy of the parking position will be reduced if the first camera 21 cannot capture an image of the entire body of the vehicle 3. For example, when the vehicle 3 backs up to park in the parking space 2, if the first camera 21 cannot capture an image of the front end of the body of the vehicle 3, the position of the vehicle front end position Pf at the time when parking into the parking space 2 is completed will be deviated from the desired position (e.g., the target front end position Ptf), and the fore-and-aft direction of the body of the vehicle 3 will be deviated from the fore-and-aft direction of the parking frame line (parking space) of the parking space 2. Similarly, when the vehicle 3 moves forward to park in the parking space 2, there is a risk that the position of the vehicle rear end position Pr will be deviated from the desired position (e.g., the target rear end position Ptr).

[0026] Therefore, in the parking assistance system 1 of the embodiment, the second image is generated by capturing an image of the surroundings of the vehicle 3 using the second camera 37 mounted on the vehicle 3. For example, when the vehicle 3 backs up to park in the parking space 2, a front image obtained by the second camera 37 capturing an image in front of the vehicle 3 may be generated as the second image. When the vehicle 3 moves forward to park in the parking space 2, a rear image obtained by the second camera 37 capturing an image behind the vehicle 3 may be generated as the second image. In other words, the second image may be an image generated by capturing an image in the direction opposite to the direction in which the vehicle 3 enters the parking space 2.

[0027] The parking assistance device 30 performs parking assistance to park the vehicle 3 at the target parking position of the parking space 2 based on the first image received from the ground device 20 and the second image generated by the second camera 37. This allows the fore-and-aft direction of the body of the vehicle 3 to be adjusted so that the shooting direction of the second camera 37 mounted on the vehicle 3 matches the shooting direction of the first camera 21 installed on the parking space 2 side. As a result, the fore-and-aft direction of the body of the vehicle 3 at the time parking into the parking space 2 is completed can be aligned with the parking frame line (parking space) of the parking space 2.

[0028] 3 is a flowchart of an example of the parking assistance method of the embodiment. In step S1, the first camera 21 of the ground device 20 installed in the parking space 2 generates a first image by capturing an image of the surroundings of the parking space 2. In step S2, the communication device 22 transmits the first image to the vehicle 3.

[0029] In step S3, the second camera 37 mounted on the vehicle 3 generates a second image by capturing an image of the surroundings of the vehicle 3. In step S4, the controller 36 executes parking assistance to park the vehicle 3 at a target parking position within the parking space 2 based on the first image and the second image.

[0030] Second Embodiment Next, a parking assistance system 1 according to a second embodiment will be described. The following description will be directed to a case where the vehicle 3 moves backward to park in the parking space 2. When the vehicle 3 moves forward to park in the parking space 2, the "vehicle front end position Pf" and "vehicle rear end position Pr" described below are interchangeable, the "target front end position Ptf" and "target rear end position Ptr" are interchangeable, and the second image is changed to an image behind the vehicle 3.

[0031] The parking assistance system 1 in the second embodiment has a schematic configuration similar to that of the high-precision system shown in Fig. 1. Fig. 4 is a block diagram showing an example of the functional configuration of the controller 36 in the second embodiment. The controller 36 includes an image information acquisition unit 40, a coordinate information acquisition unit 41, a parking path generation unit 42, a steering control unit 43, and a vehicle speed control unit 44.

[0032] The image information acquisition unit 40 acquires a first image generated by the first camera 21 of the ground device 20 and transmitted by the communication device 22 of the ground device 20. Specifically, the image information acquisition unit 40 acquires a first image received by the communication device 33 of the parking assistance device 30 from the communication device 22. The image information acquisition unit 40 also acquires a second image generated by the second camera 37 capturing an image of the area ahead of the vehicle 3.

[0033] The coordinate information acquisition unit 41 acquires the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr. For example, the coordinate information acquisition unit 41 may acquire coordinate information of the vehicle rear end position Pr in a relative coordinate system with the target rear end position Ptr as the coordinate origin. For example, the coordinate information acquisition unit 41 may receive information on the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr from the ground device 20. The controller 23 of the ground device 20 may calculate the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr based on the first image generated by the first camera 21.

[0034] For example, the controller 23 may calculate the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr based on a first image generated by the first camera 21 when the vehicle 3 or another vehicle 5 other than the vehicle 3 previously parked in the parking space 2 and a first image generated by the first camera 21 at the current time. Fig. 5(a) shows a first image Im1a generated by the first camera 21 when the other vehicle 5 previously parked in the parking space 2, and Fig. 5(b) shows a first image Im1b generated by the first camera 21 at the current time.

[0035] The controller 23 may calculate the position directly below the rear end of the other vehicle 5 appearing in the first image Im1a as the target rear end position Ptr based on information about the installation position, optical axis direction, and angle of view of the first camera 21. Similarly, the controller 23 may calculate the position directly below the rear end of the vehicle 3 appearing in the first image Im1b as the vehicle rear end position Pr. The controller 23 may calculate the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr based on the target rear end position Ptr and the vehicle rear end position Pr.

[0036] The communication device 22 of the ground device 20 may transmit information about the relative position calculated by the controller 23 to the vehicle 3. The coordinate information acquisition unit 41 may acquire the information about the relative position received by the communication device 33 of the parking assistance device 30 from the communication device 22. The coordinate information acquisition unit 41 may receive the first image Im1a and the first image Im1b from the ground device 20, and calculate the relative position of the vehicle rear end position Pr based on the first image Im1a and the first image Im1b.

[0037] The parking path generating unit 42 generates a first target parking path Tr1 that leads from the current position of the vehicle 3 to the target parking position set in the parking space 2. For example, the parking path generating unit 42 may generate a path from the vehicle rear end position Pr to the target rear end position Ptr as the first target parking path Tr1, as shown in Fig. 6, based on the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr. In this case, the first target parking path Tr1 is a trajectory generated based on the first image generated by the first camera 21.

[0038] The first target parking path Tr1 may be a path generated based on the second image generated by the second camera 37. For example, the coordinate information acquisition unit 41 may detect parking frame lines (parking sections) of the parking space 2 around the vehicle 3 based on the second image generated by the second camera 37. The coordinate information acquisition unit 41 may set a target parking position within the detected parking frame lines (parking sections) and calculate a relative position of the target parking position with respect to the current position of the vehicle 3. The parking path generation unit 42 may generate the first target parking path Tr1 based on the relative position calculated by the coordinate information acquisition unit 41.

[0039] The steering control unit 43 and the vehicle speed control unit 44 control the steering actuator 35a, the accelerator actuator 35b, and the brake actuator 35c so that the vehicle 3 travels along the first target parking path Tr1 from the start of the parking assistance until the vehicle 3 reaches the intermediate position Pim on the first target parking path Tr1. Alternatively or in addition to this, the controller 36 may display the first target parking path Tr1 and the current position of the vehicle 3 on the HMI 34 from the start of the parking assistance until the vehicle 3 reaches the intermediate position Pim.

[0040] The intermediate position Pim is a position midway between the position of the vehicle 3 at the time when parking assistance is started and the target parking position. For example, the intermediate position Pim may be a position a predetermined distance from the parking space 2 or the target parking position (e.g., the target rear end position Ptr). Furthermore, for example, the intermediate position Pim may be a point where the rear end of the vehicle 3 reversing into the parking space 2 enters the parking frame line of the parking space 2, or a point where the front end of the vehicle 3 moving forward into the parking space 2 enters the parking frame line of the parking space 2. Furthermore, for example, the intermediate position Pim may be a point where the difference between the yaw angle of the vehicle 3 parked at the target parking position in the parking space 2 (e.g., the front-rear direction of the parking frame line or the parking space) and the yaw angle of the vehicle 3 traveling along the first target parking path Tr1 to the target parking position decreases to a predetermined value.

[0041] 7 , when the vehicle 3 travels to the intermediate position Pim, the coordinate information acquisition unit 41 calculates the relative position of the vehicle front end position Pf with respect to the target rear end position Ptr or the target front end position Ptf, based on the first image received from the ground device 20 and the second image generated by the second camera 37. A straight line OX1 indicates the optical axis direction of the second camera 37 when the vehicle 3 is parked so that the vehicle front end position Pf coincides with the target front end position Ptf and the vehicle rear end position Pr coincides with the target rear end position Ptr.

[0042] In the following description, a state in which the vehicle 3 is parked so that the vehicle front end position Pf coincides with the target front end position Ptf and the vehicle rear end position Pr coincides with the target rear end position Ptr may be referred to as a "target parking state." Note that the front-rear direction of the vehicle 3 in the target parking state may be the same as the front-rear direction of the parking frame line of the parking space 2. In other words, the optical axis direction OX1 may be the same as the front-rear direction of the parking frame line.

[0043] The straight line OX2 indicates the current optical axis direction of the second camera 37. For example, the coordinate information acquisition unit 41 may calculate the angle θ formed by the optical axis directions OX1 and OX2 based on the first image and the second image. An example of a method for calculating the angle θ will be described with reference to Figures 8(a) and 8(b). Figure 8(a) is a diagram showing an example of the first image Im1.

[0044] The dashed line Rc indicates the range of the image range of the first image Im1 that corresponds to the capture range of the second camera 37 in the target parking state. The cropped image Im1c in Fig. 8(a) is an image cropped from the range Rc of the first image Im1. Fig. 8(b) is a diagram showing an example of the second image Im2. For example, the coordinate information acquisition unit 41 may detect common feature points Pf1 and Pf2 that appear in both the cropped image Im1c and the second image Im2.

[0045] The coordinate information acquisition unit 41 may calculate the direction in which the feature point Pf1 is visible from the position of the second camera 37 in the target parking state, based on the angle of view on the cropped image Im1c and the position of the feature point Pf1 on the cropped image Im1c. The angle of view of the cropped image Im1c can be determined according to the angle of view of the first camera 21 and the size of the cropping range R. Note that the optical axis of the first camera 21 may be in the same direction as the fore-and-aft direction of the vehicle 3 and the fore-and-aft direction of the parking frame lines in the target parking state, and the vehicle front end position Pf may be set on or near the optical axis of the first camera 21.

[0046] Similarly, the coordinate information acquisition unit 41 may calculate the direction in which the feature point Pf2 is visible from the current position of the second camera 37, based on the angle of view of the second image Im2 and the position of Pf2 on the second image Im2. The coordinate information acquisition unit 41 may calculate the angle θ between the optical axis direction OX1 of the second camera 37 in the target parking state and the current optical axis direction OX2 of the second camera 37, based on the difference between the directions in which the feature points Pf1 and Pf2 are visible. To facilitate the calculation of the angle θ, cameras having the same angle of view and image sensors may be used as the first camera 21 of the ground device 20 and the second camera 37 of the vehicle 3.

[0047] The coordinate information acquisition unit 41 may calculate the relative position of the vehicle front end position Pf with respect to the target rear end position Ptr based on known vehicle specifications such as the overall length of the vehicle 3, the angle θ, and the relative position of the vehicle rear end position Pr with respect to the target rear end position Ptr. For example, the coordinate information acquisition unit 41 may calculate the optical axis direction OX2 in a relative coordinate system with the target rear end position Ptr as the coordinate origin based on the angle θ, and calculate the position displaced from the vehicle rear end position Pr in the direction of the optical axis direction OX2 by the overall length of the vehicle 3 as the vehicle front end position Pf.

[0048] On the other hand, the target front end position Ptf can be determined based on known vehicle specifications such as the overall length of the vehicle 3 and the target rear end position Ptr. For example, the target front end position Ptf is determined to be a position displaced from the target rear end position Ptr by the entire length of the vehicle 3 in a forward direction of the parking frame line of the parking space 2. The coordinate information acquisition unit 41 may calculate the relative position of the vehicle front end position Pf with respect to the target front end position Ptf based on the relative position of the vehicle front end position Pf with respect to the target rear end position Ptr and the target front end position Ptf.

[0049] The controller 23 of the ground device 20 may transmit the first image to the vehicle 3 at multiple points in time as the vehicle 3 travels from the intermediate position Pim to the target parking position (i.e., may transmit the first image multiple times to the vehicle 3). For example, the controller 23 may periodically transmit the first image sequentially to the vehicle 3. By transmitting the first image at multiple points in time in this manner, a first image with good photographic conditions can be selected and used to calculate the vehicle front end position Pf.

[0050] The controller 36 adjusts the vehicle front end position Pf so as to reduce the horizontal deviation between the cropped image Im1c and the second image Im2 while the vehicle 3 travels from the intermediate position Pim to the target parking position. Specifically, the parking path generator 42 calculates the second target parking path Tr2 based on the relative positional relationships among the vehicle front end position Pf, the vehicle rear end position Pr, the target front end position Ptf, and the target rear end position Ptr. For example, the parking path generator 42 calculates the second target parking path Tr2 that aligns the vehicle front end position Pf with the target front end position Ptf and simultaneously aligns the vehicle rear end position Pr with the target rear end position Ptr. The steering control unit 43 and the vehicle speed control unit 44 control the steering actuator 35a, the accelerator actuator 35b, and the brake actuator 35c so that the vehicle 3 travels along the second target parking path Tr2 until the vehicle 3 reaches the target parking position from the intermediate position Pim (i.e., until the vehicle front end position Pf coincides with the target front end position Ptf and the vehicle rear end position Pr coincides with the target rear end position Ptr). Alternatively or in addition to this, the controller 36 may display the second target parking path Tr2 and the current position of the vehicle 3 on the HMI 34 until the vehicle 3 reaches the target parking position from the intermediate position Pim.

[0051] If the position of the second camera 37 in the target parking state differs from the position of the second camera 37 during parking, an error other than that due to the difference in the shooting direction will occur between the cropped image Im1c in Fig. 8(a) and the second image Im2 in Fig. 8(b). As a result, there is a risk of an error occurring in the vehicle front end position Pf calculated based on the cropped image Im1c and the second image Im2.

[0052] Therefore, the coordinate information acquisition unit 41 may recalculate the positions of the vehicle front end position Pf and the vehicle rear end position Pr at multiple points in time during the period from the intermediate position Pim to the target parking position of the vehicle 3. The parking path generation unit 42 may update the second target parking path Tr2 based on the recalculated positions of the vehicle front end position Pf and the vehicle rear end position Pr.

[0053] (Advantages of the embodiment) (1) In the parking assistance method, a first image is generated by capturing an image of the surroundings of the parking space using a first camera installed in the parking space, the first image is transmitted to the vehicle, a second image is generated by capturing an image of the surroundings of the vehicle using a second camera installed in the vehicle, and parking assistance is performed to park the vehicle in a target parking position within the parking space based on the first image and the second image. This improves the accuracy of the parking position in parking assistance using a camera installed in the parking space.

[0054] (2) Parking assistance may be performed based on either the first image or the second image from the parking start position to an intermediate position on the way to the target parking position, and parking assistance may be performed based on both the first image and the second image from the intermediate position to the target parking position. This allows the difference in the shooting direction between the first image and the second image to be detected when the vehicle 3 approaches the target parking position and the shooting ranges of the first image and the second image overlap, and the orientation of the vehicle 3 being parked in the parking space to be adjusted based on the difference in the shooting direction between the first image and the second image.

[0055] (3) The intermediate position may be a point a predetermined distance from the parking space or the target parking position, a point where the difference between the yaw angle of the vehicle parked at the target parking position and the yaw angle of the vehicle traveling to the target parking position is a predetermined value, or a point where the rear end of the vehicle reversing into the parking space enters the parking frame line of the parking space. This makes it possible to detect the difference in the shooting direction between the first image and the second image while the shooting ranges of the first image and the second image sufficiently overlap.

[0056] (4) The first image may be transmitted to the vehicle at a plurality of times as the vehicle travels from the intermediate position to the target parking position. This allows parking assistance to be performed using the first image captured in a good state.

[0057] (5) The first camera may be installed at one of the longitudinal ends of the parking space, opposite the end where the vehicle parks in the parking space. This allows the first camera and the second camera to overlap when an onboard camera capturing an image in the direction opposite to the vehicle's approach into the parking space is used as the second camera and a fixed camera capturing an image of the vehicle parking in the parking space is used as the first camera. This allows the difference in the capturing direction between the first image of the first camera and the second image of the second camera to be detected, and the orientation of the vehicle 3 parked in the parking space to be adjusted based on the difference in the capturing direction.

[0058] (6) The front end position of the vehicle that is being reversed and parked into the target parking position may be adjusted based on the first image and the second image. For example, the front end position may be adjusted so as to reduce the horizontal deviation between the first image and the second image. This improves the accuracy of the parking position.

[0059] All examples and conditional terms described herein are intended for educational purposes to aid the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology, and should be construed without limitation to the specifically described examples and conditions above, and the configuration of examples herein for illustrating the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present invention.

[0060] 1...Parking assistance system, 2...Parking space, 3...Vehicle, 20...Ground device, 21...First camera, 22, 33...Communication device, 23, 36...Controller, 23a, 36a...Processor, 23b, 36b...Storage device, 30...Parking assistance device, 31...Object sensor, 32...Vehicle sensor, 33...Communication device, 35a...Steering actuator, 35b...Accelerator actuator, 35c...Brake actuator, 37...Second camera, 40...Image information acquisition unit, 41...Coordinate information acquisition unit, 42...Parking path generation unit, 43...Steering control unit, 44...Vehicle speed control unit

Claims

1. A parking assistance method comprising: generating a first image by photographing the surroundings of a parking space with a first camera installed in the parking space; transmitting the first image to a vehicle; generating a second image by photographing the surroundings of the vehicle with a second camera mounted on the vehicle; and performing parking assistance to park the vehicle in a target parking position within the parking space based on the first image and the second image.

2. The parking assistance method according to claim 1, characterized in that the parking assistance is performed based on either the first image or the second image from the parking start position to an intermediate position on the way to the target parking position, and the parking assistance is performed based on both the first image and the second image from the intermediate position to the target parking position.

3. The parking assistance method according to claim 2, wherein the intermediate position is a point at a predetermined distance from the parking space or the target parking position, a point at which a difference between the yaw angle of the vehicle when parked at the target parking position and the yaw angle of the vehicle while traveling to the target parking position decreases to a predetermined value, or a point at which the rear end of the vehicle backing up into the parking space enters the parking frame line of the parking space.

4. The parking assistance method according to claim 2 or 3, characterized in that the first image is transmitted to the vehicle at a plurality of times as the vehicle travels from the intermediate position to the target parking position.

5. A parking assistance method as described in any one of claims 1 to 4, characterized in that the first camera is installed at one of the two ends of the parking space in the forward / backward direction, opposite the end where the vehicle parks in the parking space.

6. A parking assistance method as described in any one of claims 1 to 5, characterized in that the front end position of the vehicle that is backing up and parking into the target parking position is adjusted based on the first image and the second image.

7. The parking assistance method according to claim 6, further comprising adjusting the front end position so as to reduce the horizontal deviation between the first image and the second image.

8. A parking assistance device comprising: a communication device that receives a first image generated by a first camera installed in a parking space photographing the surroundings of the parking space; a second camera mounted on a vehicle that photographs the surroundings of the vehicle and generates a second image; and a controller that executes parking assistance to park the vehicle in a target parking position within the parking space based on the first image and the second image.

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