Parking assistance device

Abstract

The purpose of the present invention is to provide a parking assistance device capable of parking a vehicle in a narrow parking space between a front obstacle and a rear obstacle with a small number of direction reversals while reliably avoiding contact between a front end of the vehicle and the front obstacle. For this purpose, a route generation unit (13) generates a parking route (50) so as to include: a straight route (52) in which the position of a vehicle (60) when a first obstacle detection sensor (62) mounted on a rear part of the side surface of the vehicle (60) passes beside a front obstacle (81) is defined as a start position (92), and the position of the vehicle (60) when the front end of the vehicle (60) passes beside the front obstacle (81) is defined as an end position (93); and a circular turning route (54) that makes a turn at the maximum steering angle from the end position (93) of the straight route (52) to a first direction-reversal position (94) within a parking space (70).

Description

Parking support device

[0001] The present invention relates to a parking support device that supports the parking operation of a vehicle.

[0002] Driving support systems have been developed to prevent traffic accidents and reduce the driving load on drivers during traffic jams. One of the driving support systems is a parking support device. The parking support device automatically performs some or all of the operations of the accelerator, brake, steering, shift, and parking brake, and has a function of parking the vehicle in a target parking frame presented by the driver. One of the parking patterns for parking support is parallel parking, and it is required that the vehicle can be parked in a narrow parking frame with a small number of turns. Patent Documents 1 and 2 disclose prior art of the parking support device. Patent Document 1 discloses a method in which when the vehicle is parked in parallel, the parking path when the front end of the vehicle passes by the side of the front obstacle is a circular turning path (see FIG. 15). Further, Patent Document 2 discloses a method in which the parking path when the front end of the vehicle passes by the side of the front obstacle is a straight path (see FIG. 10).

[0003] Japanese Patent Application Laid-Open No. 2011-899 International Publication WO2011 / 155349

[0004] However, in the parking support device described in Patent Document 1, since the vehicle enters the parking space along a circular turning path, when the front end of the vehicle passes by the side of the front obstacle, the front end of the vehicle swings horizontally. Therefore, the detection accuracy of the front obstacle decreases, and there is a risk that the front end of the vehicle collides with the front obstacle. Further, in the parking support device described in Patent Document 2, since the vehicle enters the parking space along a straight path until the rear end of the vehicle reaches the depth inside the parking space, the number of turns until the vehicle reaches the target parking position increases.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a parking support device capable of parking a vehicle with a small number of turns while surely avoiding contact between the front end of the vehicle and a front obstacle in a narrow parking space sandwiched between a front obstacle and a rear obstacle.

[0006] To achieve the above objective, the present invention provides a parking assistance device comprising: a plurality of obstacle detection sensors for detecting obstacles around a vehicle; a vehicle position calculation unit for calculating the position of the vehicle; a target parking position calculation unit for calculating a target parking position in a parking space sandwiched between a front obstacle and a rear obstacle; a path generation unit for generating a parking path from the current position of the vehicle to the target parking position; and a vehicle control unit for driving the vehicle along the parking path. The plurality of obstacle detection sensors include a first obstacle detection sensor mounted on the rear side of the vehicle, and the path generation unit generates the parking path to include a straight path where the vehicle's position when the first obstacle detection sensor passes beside the front obstacle is the starting position and the vehicle's position when the front end of the vehicle passes beside the front obstacle is the ending position, and a circular turning path where the vehicle turns at the maximum steering angle from the ending position of the straight path to the first turning position in the parking space.

[0007] According to the present invention, it is possible to park a vehicle in a narrow parking space sandwiched between an obstacle in front and an obstacle behind, while reliably avoiding contact between the front end of the vehicle and the obstacle in front, and with fewer maneuvers.

[0008] This is a diagram of the parking assistance system configuration. This is a diagram showing an example of a parking route. This is a flowchart showing the processing of the parking control unit. This is a diagram showing the type of route connecting the initial turning position outside the space and the starting position of the straight route. This is a diagram showing the method for calculating the initial turning position outside the space. This is a conceptual diagram of the range of the initial turning position within the space. This is a diagram showing the operation of repeatedly moving forward and backward at the maximum steering angle in the direction of escaping the parking space from the target parking position. This is a diagram explaining the effect of providing a straight route in the parking route. This is a diagram explaining the effect of providing a straight route in the parking route. This is a diagram explaining the effect of providing a straight route in the parking route. This is a diagram explaining the effect of stopping at the end position of the straight route and performing stationary steering.

[0009] Embodiments of the present invention will be described below with reference to the drawings. In each figure, equivalent components are denoted by the same reference numerals, and redundant explanations are omitted.

[0010] Figure 1 is a diagram showing the configuration of the parking assist device 1. The parking assist device 1 comprises a parking control unit 10, a navigation system 20, an external environment recognition sensor 31, a vehicle sensor 32, an engine 41, a brake 42, a steering wheel 43, and a transmission 44. The external environment recognition sensor 31 and the vehicle sensor 32 are connected to the parking control unit 10 via an in-vehicle network 10a. The engine 41, brake 42, steering wheel 43, and transmission 44 are connected to the parking control unit 10 via an in-vehicle network 10b. The external environment recognition sensor 31 consists of a camera, sonar, radar, LiDAR, etc., and is installed, for example, in front of, behind, and on the sides of a vehicle 60 (shown in Figure 2). The external environment recognition sensor 31 also serves as an obstacle detection sensor that detects obstacles around the vehicle 60. The vehicle sensor 32 consists of a wheel speed pulse, GPS (Global Positioning System), GNSS (Global Navigation Satellite System), gyro sensor, etc.

[0011] The parking control unit 10 includes a recognition unit 11, a target parking position calculation unit 12, a path generation unit 13, a correction calculation unit 14, a vehicle position calculation unit 15, and a vehicle control unit 16.

[0012] The recognition unit 11 recognizes a parking space 70 (shown in Figure 2), which is a space where parking is possible, based on the parking space lines of the parking lot and adjacent vehicles already parked in the parking lot, as detected by the external environment recognition sensor 31. The recognition unit 11 also recognizes the width of the passage 80 (shown in Figure 2) where a path outside the parking space 70 is generated, and the area in front of the passage 80, based on the detection results around the parking space 70.

[0013] The target parking position calculation unit 12 calculates the target parking position 71 (shown in Figure 2), which is the position where the vehicle 60 should be parked in the parking space 70 recognized by the recognition unit 11. The position of the vehicle 60 is defined by a predetermined position of the vehicle 60 (in this embodiment, the left-right center position of the rear axle) and the yaw angle of the vehicle 60. The target parking position 71 is defined by the position 71a of the predetermined position when the vehicle 60 is parked at the target parking position 71 and the yaw angle (target parking position yaw angle 71b). The target parking position 71 is calculated from the relationship between the dimensions of the vehicle 60 and the parking space 70. The target parking position 71 is updated not only before the start of parking assistance but also after the start of parking assistance according to the latest obstacle information.

[0014] The route generation unit 13 generates a parking route 50 (shown in Figure 2) from the vehicle 60's current position to the target parking position 71 within the area inside and outside the parking space 70 recognized by the recognition unit 11. The parking route 50 can be generated not only when the vehicle 60 is stopped, but also when it is moving, provided that the external environment recognition sensor 31 is highly accurate.

[0015] The correction calculation unit 14 corrects the parking path 50 according to the obstacle information detected while driving along the parking path 50.

[0016] The vehicle position calculation unit 15 calculates the current position of the vehicle 60 from the information of the vehicle sensor 32.

[0017] The vehicle control unit 16 controls various actuators, as well as the engine 41 and transmission 44, based on information from the vehicle sensor 32, the external environment recognition sensor 31, etc., to automatically drive the vehicle 60 into or out of the parking lot. The vehicle control unit 16 switches the direction of travel of the vehicle 60 forward or backward by controlling the transmission 44. Here, switching from forward to backward or backward to forward is defined as a change of direction, and the number of such changes is defined as the number of changes of direction. The vehicle control unit 16 also controls the engine 41, brakes 42 and steering 43 so that the vehicle 60 travels along the parking path 50, based on the path information from the path generation unit 13 and the vehicle position information from the vehicle position calculation unit 15. The vehicle control unit 16 also performs stationary steering as needed. Stationary steering is turning the steering wheel while the vehicle 60 is stationary.

[0018] The navigation system 20 includes an operation unit 21 and a display unit 22 that perform information input and output with the driver as a human-machine interface, and the display unit 22 displays parking spaces, parking routes 50, etc.

[0019] Figure 2 shows an example of a parking path 50. The parking control unit 10 guides the vehicle 60 to the target parking position 71 within the parking space 70 by making the vehicle 60 travel along the parking path 50. The parking space 70 is a rectangular area enclosed by a front obstacle 81, a rear obstacle 82, and a side obstacle 83. The front obstacle 81 and rear obstacle 82 are other vehicles or structures, and the side obstacle 83 is a curb or structure. In the front area of ​​the passage 80 adjacent to the parking space 70, there may be structures such as a front wall 84 or side walls 85. The parking path 50 includes a path 51 connecting the vehicle's position when parking begins (parking start position 90) and the turning position where the vehicle first switches to reverse outside the parking space 70 (initial turning position outside the space 91), a straight path 52 entering the parking space 70 from outside the parking space 70, a path 53 connecting the initial turning position outside the space 91 and the start position 92 of the straight path 52, a circular turning path 54 connecting the end position 93 of the straight path 52 and the turning position where the vehicle first switches to forward inside the parking space 70 (initial turning position inside the space 94), and a path (not shown) that connects to the target parking position 71 by repeatedly moving forward, turning, reversing, and turning from the initial turning position inside the space 94. Here, the connection of two paths means not only that the two paths share one position, but also that the tangential directions of the two paths at that one position coincide.

[0020] Figure 3 is a flowchart showing the processing of the parking control unit 10. The program shown in this flowchart can be executed by a computer equipped with a CPU, memory, etc. All or part of the processing may be implemented by hard logic circuits. This program can be provided in advance by being stored in the storage medium of the parking control unit 10. Alternatively, the program can be provided by being stored in an independent recording medium, or the program can be recorded and stored in the storage medium of the parking control unit 10 via a network line. Here, we will explain using the case where the parking pattern of the recognized parking space is parallel parking and the parking space 70 is narrow as an example.

[0021] The parking control unit 10 first starts searching for a parking space using the recognition unit 11 in response to a parking assistance activation operation by the driver, which is input from the operation unit 21 of the navigation system 20 (step S01). The recognition unit 11 uses information such as parking space lines and adjacent vehicles obtained from the external environment recognition sensor 31 to detect a parking space 70 in which the vehicle 60 can park. The parking space found in step S01 is displayed on the display unit 22 of the navigation system 20.

[0022] Following step S01, the driver selects and confirms a desired parking space using the control panel 21 of the navigation system 20 (step S02).

[0023] Following step S02, the route generation unit 13 calculates the target parking position 71 for the parking space determined in step S02 (step S03).

[0024] Following step S03, the path generation unit 13 generates a parking path 50 within the area inside and outside the parking space 70 recognized by the recognition unit 11, based on the target parking position 71 calculated in step S03 (step S04).

[0025] The path generation unit 13 generates a parking path 50 that includes a straight path 52 and a circular turning path 54 when the parking pattern is parallel parking and the parking space 70 is narrow. Specifically, a narrow parking space 70 means that the distance between the front obstacle 81 and the rear obstacle 82 (the length of the parking space 70) is less than the total length of the vehicle plus a predetermined value, or that the length of the parking space is less than the total length of the vehicle multiplied by a predetermined coefficient greater than 1.

[0026] The path generation unit 13 calculates and combines paths 52 and 54 from the target parking position 71 to the starting position 92 of the straight path 52, and paths 51 and 53 from the parking start position 90 to the starting position 92 of the straight path 52, respectively, to generate a parking path 50 from the parking start position 90 to the target parking position 71.

[0027] The path generation unit 13 first calculates paths 52 and 54 from the target parking position 71 to the starting position 92 of the straight path 52 in the opposite direction to the parking operation of the vehicle 60.

[0028] The path generation unit 13 uses the latest obstacle position information and the target parking position 71 set based on it to calculate a path that starts from the target parking position 71 and repeatedly moves forward and backward at the maximum steering angle that points the front end of the vehicle outward from the parking space 70, until the end of the vehicle 60 contacts one of the boundary lines 70a to 70c between the parking space 70 and the obstacles 81 to 83.

[0029] The path generation unit 13 determines at each position of the path, which involves repeated forward and backward movement, whether it is possible to move to a position where the front end of the vehicle 60 on the side of the lateral obstacle 83 is outside the parking space 70 without contacting any of the boundary lines 70a to 70c, by turning the steering wheel to the maximum angle in the direction of exiting the parking space 70 at that position, and then moving forward one more time. The position where it is first determined that it is possible to exit the space is designated as the first turning position 94 within the space. Here, the position where the front end of the vehicle 60 on the side of the lateral obstacle 83 is outside the parking space 70 is the end position 93 of the straight path 52, that is, the position where the vehicle 60 is stopped and the steering wheel is turned. From the end position 93 of the straight path 52 to the first turning position 94 within the space, the path becomes a circular turning path 54, where the vehicle turns at the maximum steering angle.

[0030] The yaw angle of the vehicle 60 at the end position 93 of the straight path 52 becomes the angle of the straight path 52. From the end position 93 of the straight path 52, the straight path 52 is extended outside the parking space 70 at that angle, and the straight path 52 is defined as the position 92 where the accuracy of detecting the obstacle 81 ahead is predicted to be highest when the vehicle 60 enters the parking space 70. Position 92 becomes the starting position 92 of the straight path 52.

[0031] The starting position 92 of the straight-ahead path 52 is set according to the mounting position and characteristics of the sensor, with the aim of stabilizing the vehicle's behavior by the time when the sensor, which is intended to detect the obstacle 81 in front of the vehicle, can accurately detect the obstacle 81 in front of the vehicle, in order to improve the accuracy of detecting the obstacle 81 in front of the vehicle.

[0032] If the means for detecting the obstacle 81 in front is a front side sonar 61 and a rear side sonar 62 mounted on the side of the vehicle, the mounting position of the rear side sonar 62 is such that the position 92 passing beside the obstacle 81 in front becomes the starting position 92 of the straight path 52.

[0033] Next, routes 51 and 53 are generated from the parking start position 90 to the starting position 92 of the straight-ahead route 52.

[0034] In multiple types of paths, each consisting of one or more combinations of a circular turn, a clothoid, and a straight path, that connect to the starting position 92 of the straight path 52, the system calculates the positions that can be connected from the parking starting position 90 within the limits of the width of the passage 80 adjacent to the parking space 70 and the forward area of ​​the passage 80.

[0035] Figure 4 shows the type of path connecting the initial out-of-space turning point 91 and the starting point 92 of the straight path 52.

[0036] Route type 1 is a route that connects to the starting position 92 of the straight route 52 via a straight-to-circular turn. The number of stationary turns required to connect to the starting position 92 of the straight route 52 is determined by the initial out-of-space turning position 91. If the initial out-of-space turning position 91 is on the straight route as shown in the figure, it will require two turns: one after the straight route and one after the circular turn. If the initial out-of-space turning position 91 is on the circular turn route, it will require one turn after the circular turn.

[0037] Route type 2 is a route that connects to the starting position 92 of the straight route 52 via a straight line - clothoid - circular turn. In this case, the number of steering wheel turns is one after the circular turn.

[0038] Route type 3 is a route that connects to the starting position 92 of the straight route 52 via a straight line - circular turn - clothoid. The number of stationary steering turns required to connect to the starting position 92 of the straight route 52 is determined by the initial out-of-space steering position 91. If the initial out-of-space steering position 91 is on the straight route as shown in the figure, it will be 1 turn after the straight route; if the initial out-of-space steering position 91 is not on the straight route, it will be 0 turns.

[0039] Route type 4 is a route that connects to the starting position 92 of the straight route 52 via a straight line - clothoid - circular turn - clothoid route. In this case, the straight route and the circular turn route are not directly connected, so the number of stationary steering turns is 0.

[0040] Route type 5 is a route that continues straight and connects to the starting position 92 of the straight route 52. In this case, steering is not required, so the number of stationary steering turns is 0.

[0041] The route generation unit 13 calculates, for each route type, the position 95 in which the vehicle 60 can move furthest forward within the limits of the width of the passage 80 and the forward area of ​​the passage 80, as shown in Figure 5. The route from position 95 to the starting position 92 of the straight route 52 is defined as the connection feasibility confirmation range 55, and the unit calculates the positions that can be connected from the parking start position 90 within the connection feasibility confirmation range 55. Next, the unit calculates the number of steering turns and the route distance for each connectable position. The route distance here refers to the distance from the parking start position 90 to the starting position 92 of the straight route 52 via the connection position. If there are multiple connectable positions, the connection position with the minimum route distance among the connection positions with the minimum number of steering turns is defined as the first out-of-space steering position 91, and the route from the parking start position 90 to the starting position 92 of the straight route 52 is calculated. As a result, the parking route 50 from the parking start position 90 to the target parking position 71 is generated, and the system is ready to start parking assistance.

[0042] Returning to FIG. 3, following step S04, upon an operation to start parking assistance being inputted by the driver to the operation unit 21 of the navigation system 20, the parking control unit 10 starts vehicle control for parking by automatic driving (step S05).

[0043] Following step S05, the vehicle control unit 16 advances the vehicle 60 to the out-of-space first turning position 91 according to the parking route 50 calculated in step S04 (step S06).

[0044] Following step S06, the vehicle control unit 16 stops the vehicle 60 at the out-of-space first turning position 91 (step S07). At this time, if the recognition information has been updated, the route generation unit 13 regenerates the parking route 50 based on the latest recognition information.

[0045] Following step S07, the vehicle control unit 16 switches the traveling direction of the vehicle 60 from forward to backward (step S08).

[0046] Following step S08, the vehicle control unit 16 starts the backward movement of the vehicle 60 (step S09).

[0047] Following step S09, the vehicle 60 determines whether it has passed the start position 92 of the straight travel route 52 (step S10).

[0048] Following step S10, the correction calculation unit 14 corrects the offset of the straight travel route 52 generated for the first time based on the position information of the latest front obstacle 81 detected by the rear side sonar 62 (step S11). When the detection means of the front obstacle 81 is the front side sonar 61 and the rear side sonar 62 mounted on the side of the vehicle, the correction is performed based on the obstacle position information detected by the rear side sonar 62.

[0049] Following step S11, the correction calculation unit 14 corrects the end position 93 of the straight travel route 52 based on the position information of the latest front obstacle 81 detected by the obstacle detection sensors 31, 61, 62 near the end position 93 of the straight travel route 52. When the detection means of the front obstacle 81 is the front side sonar 61 and the rear side sonar 62 mounted on the side of the vehicle, the correction is performed based on the obstacle information detected by the front side sonar 61 (step S12).

[0050] Following step S12, the vehicle control unit 16 stops the vehicle 60 at the end position 93 of the straight path 52 corrected in steps S11 and S12 (step S13).

[0051] Following step S13, the vehicle control unit 16 calculates the initial turning position range 72 in space based on the latest recognition information and calculates the steering angle that can connect the vehicle 60's stopping position (end position 93 of the straight path 52) to the initial turning position range 72 in space (shown in Figure 6) (step S14).

[0052] Figure 6 is a conceptual diagram of the initial reversal position range 72 in space. The method for calculating the initial reversal position range 72 in space will be explained below.

[0053] The path generation unit 13 uses the latest obstacle position information and the target parking position 71 set based on it to calculate a path that repeatedly moves forward and backward at the maximum steering angle in the direction of escaping the parking space 70 from the target parking position 71. Specifically, as shown in Figure 7, it calculates a path that moves the vehicle 60 at the maximum steering angle until the vehicle 60 contacts one of the boundary lines 70a to 70c of the parking space 70, and then switches between moving forward and backward.

[0054] Returning to Figure 6, the path generation unit 13 determines at each position of the path, which involves repeated forward and backward movement, whether it is possible to move to a position where the front end of the vehicle 60 on the side of the lateral obstacle 83 is outside the parking space 70 without contacting any of the boundary lines 70a to 70c of the parking space 70 (space escape possible) with the remaining forward movement, and the position 96 (shown in Figure 7) where it is first determined that space escape is possible is designated as the first turning position in the space (1-a).

[0055] If it is possible to reverse further from position (1-a) until contact is made with any of the boundary lines 70a to 70c of the parking space 70, the circular reversing path is extended, and the position where contact is made with any of the boundary lines 70a to 70c of the parking space 70 is calculated and designated as the initial turning position (1-b) within the space. If it is possible to connect from the initial turning position (1-a) within the space to a position within the curved section of (1-b), parking can be achieved with the same number of turns. Furthermore, if there is a path where the same number of turns is achieved with a steering angle smaller than the maximum steering angle, the initial turning position range 72 within the space can be expanded.

[0056] The method for expanding the initial reversal position range 72 in space is described below.

[0057] While gradually decreasing the steering angle from the maximum steering angle, calculate the positions (2-a), (2-b), (3-a), (3-b), ..., (n-a), (n-b) corresponding to the initial steering position (1-a), (1-b) in space calculated at the maximum steering angle until the number of steering corrections exceeds that at the maximum steering angle.

[0058] The ranges of (1-a) to (1-b), (2-a) to (2-b), (3-a) to (3-b), ..., ((n-1)-a) to ((n-1)-b) for each steering angle that result in the same number of turns as calculated at the maximum steering angle are combined to form the initial turning position range 72 in space. If it is possible to connect to a position within the initial turning position range 72 in space, parking can be achieved with the same number of turns as at the maximum steering angle.

[0059] Returning to Figure 3, following step S14, the path generation unit 13 determines whether it is possible to calculate a steering angle that can connect to the initial turning position range 72 in space calculated in step S14, starting from the stopping position of the vehicle 60 (end position 93 of the straight path 52) (step S15).

[0060] If the result of step S15 is YES, the vehicle control unit 16 steers the vehicle to the steering angle calculated in step S14 (stationary steering) (step S16).

[0061] Following step S16, the vehicle control unit 16 rotates the vehicle 60 in a circular motion (step S17).

[0062] Following step S17, the vehicle control unit 16 stops the vehicle 60 at the connection position calculated in step S14 and calculates the initial turning position range 72 in space based on the latest recognition information (step S18). The method for calculating the initial turning position range 72 in space is as described above.

[0063] Following step S18, the vehicle control unit 16 determines whether the stopping position of the vehicle 60 is within the initial turning position range 72 in space calculated in step S18 (step S19).

[0064] If the result of the determination in step S19 is NO, or if the result of the determination in step S15 is NO, the route generation unit 13 regenerates the parking route 50 (step S20).

[0065] The method for regenerating the parking route 50 is described below.

[0066] Using the latest obstacle positions and the target parking position 71 set based on them, a path is generated from the current vehicle position in the direction of entering the parking space 70, and a path is generated that exits the parking space 70 and then enters the parking space 70, and the path with the fewest number of turns is selected as the new parking path 50.

[0067] In generating a path in the direction of entering the parking space 70, the vehicle's front end is steered toward the parking space 70, and the vehicle repeatedly moves forward and backward to generate a path to the target parking position 71.

[0068] In generating a route that involves exiting the parking space 70 and then re-entering it, the system generates a straight reverse route into the parking space 70 using the same method as the initial route generation, based on the latest obstacle positions and the target parking position 71 set accordingly. It then calculates the positions that can be connected to this straight route from the vehicle's stopping position. Through this method, the parking route 50 is regenerated.

[0069] If the result of step S19 is YES, or following step S20, the vehicle control unit 16 continues control according to the parking path 50 (step S21). Specifically, it repeatedly moves the vehicle 60 forward and backward within the parking space 70 according to the parking path 50.

[0070] Following step S21, the vehicle control unit 16 stops the vehicle 60 at the target parking position 71 (step S22), and the flow ends.

[0071] Next, we will explain the effects of providing a straight-ahead path 52 to the parking path 50.

[0072] As shown in Figure 8A, when the vehicle passes alongside the obstacle 81 in front of it via a clothoid or circular path 56, the yaw angle of the vehicle 60 changes, which reduces the detection accuracy of the obstacle 81 in front of it. In contrast, in this embodiment, as shown in Figure 8B, by passing alongside the obstacle 81 in front of it via a straight path 52, the yaw angle of the vehicle 60 does not change, thus improving the detection accuracy of the obstacle 81 in front of it.

[0073] Furthermore, as shown in Figure 9A, when reversing along a clothoid or circular turning path 57, if the steering angle is turned while turning and an additional steering adjustment is required, the vehicle will encounter the full steering limit, raising concerns about the vehicle's ability to follow from the path 57 before offset correction to the path 57a after offset correction. In contrast, in this embodiment, as shown in Figure 9B, the vehicle reverses along a straight path 52 with a small steering angle, making it easy for the vehicle 60 to follow the straight path 52a after offset correction.

[0074] Next, we will explain the effect of stopping at the end position 93 of the straight path 52 and turning the steering wheel while stationary.

[0075] As shown in Figure 10, by stopping at the end position 93 of the straight path 52 and turning the steering wheel while stationary, the vehicle 60 can be made to make a tighter turn, making it possible to bring the yaw angle of the vehicle 60 closer to the target parking position yaw angle 71b more quickly. In addition, by starting the turn from the position immediately after the front end of the vehicle has passed the obstacle 81, that is, from a position where the front end of the vehicle does not collide with the obstacle 81, it is possible to prevent the interruption of the parking operation due to the activation of the obstacle stopping function in response to the obstacle 81, and to improve the driver's sense of security.

[0076] (Summary) In this embodiment, a parking assistance device 1 comprises a plurality of obstacle detection sensors 31, 61, 62 for detecting obstacles 81 to 85 around the vehicle 60, a vehicle position calculation unit 15 for calculating the position of the vehicle 60, a target parking position calculation unit 12 for calculating a target parking position 71 within the parking space 70 sandwiched between a front obstacle 81 and a rear obstacle 82, a path generation unit 13 for generating a parking path 50 from the current position of the vehicle 60 to the target parking position 71, and a vehicle control unit 16 for driving the vehicle 60 along the parking path 50, wherein the plurality of obstacle detection sensors 3 1, 61, and 62 include a rear side sonar 62 (first obstacle detection sensor) mounted on the rear side of the vehicle 60. The path generation unit 13 generates a parking path 50 that includes a straight path 52, where the position of the vehicle 60 when the rear side sonar 62 passes beside the front obstacle 81 is the starting position 92, and the position of the vehicle 60 when the front end of the vehicle 60 passes beside the front obstacle 81 is the ending position 93, and a circular turning path 54, where the vehicle turns at the maximum steering angle from the ending position 93 of the straight path 52 to the first turning position 94 in the parking space 70.

[0077] As described above, this embodiment makes it possible to park the vehicle 60 in a narrow parking space 70 sandwiched between a front obstacle 81 and a rear obstacle 82 with a small number of maneuvers, while reliably avoiding contact between the front end of the vehicle and the front obstacle 81. Furthermore, since the vehicle 60 passes alongside the front obstacle 81 on the straight path 52, the yaw angle of the vehicle 60 does not change, which improves the detection accuracy of the front obstacle 81. In addition, since the vehicle 60 reverses along the straight path 52a with a small steering angle, it is possible to easily make the vehicle 60 follow the straight path 52a after offset correction. Moreover, by starting the turn from a position where the front end of the vehicle does not collide with the front obstacle 81, it is possible to prevent interruption of the parking operation due to the activation of the obstacle stopping function for the front obstacle 81, and to improve the driver's sense of security.

[0078] Furthermore, in this embodiment, the path generation unit 13 calculates a parking path 50 that includes a straight path 52 and a circular turning path 54 when the distance between the front obstacle 81 and the rear obstacle 82 is smaller than a predetermined threshold set based on the length of the vehicle 60. This makes it possible to limit parking operations along the parking path 50, which includes the straight path 52 and the circular turning path 54, to cases where the parking space 70 is narrow.

[0079] Furthermore, the parking assist device 1 in this embodiment includes a correction calculation unit 14 that corrects the offset of the straight path 52 based on the latest position information of the forward obstacle 81 acquired by the rear side sonar 62 (first obstacle detection sensor) while the vehicle 60 is reversing along the straight path 52. This prevents interruption of the parking operation due to the activation of the obstacle stopping function in response to the forward obstacle 81, and also improves the driver's sense of security.

[0080] Furthermore, the multiple obstacle detection sensors 31, 61, and 62 in this embodiment include a front side sonar 61 (second obstacle detection sensor) mounted on the front side of the vehicle 60, and the parking assist device 1 includes a correction calculation unit 14 that corrects the end position 93 of the straight path 52 based on the latest position information of the forward obstacle 81 acquired by the front side sonar 61 while the vehicle 60 is reversing along the straight path 52. This prevents interruption of the parking operation due to the activation of the obstacle stopping function in response to the forward obstacle 81, and also improves the driver's sense of security.

[0081] Furthermore, in this embodiment, the vehicle control unit 16 stops the vehicle 60 at the end position 93 of the straight path 52, and using the latest obstacle position information acquired by the multiple obstacle detection sensors 31, 61, 62 and the target parking position 71 set based on the latest obstacle position information, it calculates the range within the parking space 70 that results in the same number of turns as when the vehicle 60 moves outside the parking space 70 by repeatedly moving forward and backward at the maximum steering angle in the direction in which the front end of the vehicle 60 faces outward from the target parking position 71, as the initial turning position range 72 within the space, and determines the steering angle of the circular turning path 54 that connects the end position 93 of the straight path 52 to a position within the initial turning position range 72 within the space. This makes it possible to suppress an increase in the number of turns within the parking space 70.

[0082] Furthermore, in this embodiment, if the vehicle control unit 16 is unable to determine the steering angle for the circular turning path 54, it moves the vehicle 60 to a position different from the end position 93 of the straight-ahead path 52 and attempts to determine the steering angle for the circular turning path 54 again. This makes it possible to suppress an increase in the number of maneuvers required within the parking space 70.

[0083] Furthermore, in this embodiment, the vehicle control unit 16 stops the vehicle 60 at the end position 94 of the circular turning path 54, and using the latest obstacle position information acquired by the multiple obstacle detection sensors 31, 61, and 62 and the target parking position 71 set based on the latest obstacle position information, calculates the range within the parking space 70 that results in the same number of turns as when the vehicle 60 moves outside the parking space 70 by repeatedly moving forward and backward at the maximum steering angle in the direction in which the front end of the vehicle 60 faces outwards from the target parking position 71, as the initial turning position range 72 within the space. It then determines whether the end position 94 of the circular turning path 54 is within the initial turning position range 72 within the space, and if it determines that the end position 94 of the circular turning path 54 is within the initial turning position range 72 within the space, it continues the parking operation of the vehicle 60. This makes it possible to suppress an increase in the number of turns within the parking space 70.

[0084] Furthermore, in this embodiment, if the vehicle control unit 16 determines that the end position 94 of the circular turning path 54 is not within the initial turning position range 72 in the space, it moves the vehicle 60 to a position different from the end position 93 of the straight-ahead path 52 and re-determines the steering angle of the circular turning path 54. This makes it possible to suppress an increase in the number of turning maneuvers within the parking space 70.

[0085] Furthermore, in this embodiment, when the path generation unit 13 determines the initial out-of-space turning position 91, which is the position outside the parking space 70 where the first reversal is performed after moving forward from the parking start position 90, it determines a connection position that can be connected from the parking start position 90 within the limits of the width of the passage 80 adjacent to the parking space 70 and the forward area of ​​the passage 80, for a path consisting of one or more combinations of a circular turn, a clothoid turn, and a straight path, drawn from the starting position 92 of the straight path 52, and calculates the number of stationary turns from the connection position to the starting position 92 of the straight path 52, and the path distance from the parking start position 90 to the starting position 92 of the straight path 52. If there are multiple connection positions that minimize the number of stationary turns, the connection position that minimizes the path distance is determined as the initial out-of-space turning position 91. This makes it possible to determine the initial out-of-space turning position 91 within the limits of the width of the passage 80 adjacent to the parking space 70 and the forward area of ​​the passage 80.

[0086] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are provided to illustrate the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described.

[0087] 1...Parking assist device, 10...Parking control unit, 10a, 10b...In-vehicle network, 11...Recognition unit, 12...Target parking position calculation unit, 13...Route generation unit, 14...Correction calculation unit, 15...Vehicle position calculation unit, 16...Vehicle control unit, 20...Navigation system, 21...Operation unit, 22...Display unit, 31...External environment recognition sensor (obstacle detection sensor), 32...Vehicle sensor, 41...Engine, 42...Brake, 43...Steering, 44...Transmission, 50...Parking route, 51...Route, 52, 52a...Straight route, 53...Route, 54...Circular turn route, 55...Connection feasibility confirmation range, 56 57, 57a...route, 60...vehicle, 61...front side sonar (second obstacle detection sensor), 62...rear side sonar (first obstacle detection sensor), 70...parking space, 70a, 70b, 70c...boundary line, 71...target parking position, 71a...position, 71b...yaw angle of target parking position, 72...first turning position range within space, 80...passageway, 81...front obstacle, 82...rear obstacle, 83...side obstacle, 84...front wall (obstacle), 85...side wall (obstacle), 90...parking start position, 91...first turning position outside space, 92...start position, 93, 94...end position, 95...position.

Claims

1. A parking assistance device comprising: a plurality of obstacle detection sensors for detecting obstacles around a vehicle; a vehicle position calculation unit for calculating the position of the vehicle; a target parking position calculation unit for calculating a target parking position within a parking space sandwiched between a front obstacle and a rear obstacle; a path generation unit for generating a parking path from the current position of the vehicle to the target parking position; and a vehicle control unit for driving the vehicle along the parking path, wherein the plurality of obstacle detection sensors include a first obstacle detection sensor mounted on the rear side of the vehicle, and the path generation unit generates the parking path such that the starting position is the position of the vehicle when the first obstacle detection sensor passes beside the front obstacle and the ending position is the position of the vehicle when the front end of the vehicle passes beside the front obstacle, and the turning path is a circular turning path in which the vehicle turns at the maximum steering angle from the ending position of the straight path to the first turning position within the parking space.

2. The parking assistance device according to claim 1, wherein the path generation unit calculates the parking path including the straight path and the circular turning path when the distance between the front obstacle and the rear obstacle is smaller than a predetermined threshold set based on the length of the vehicle.

3. A parking assistance device according to claim 1, wherein the parking assistance device comprises a correction calculation unit that corrects the offset of the position of the straight path based on the latest position information of the forward obstacle acquired by the first obstacle detection sensor while the vehicle is reversing along the straight path.

4. A parking assistance device according to claim 1, wherein the plurality of obstacle detection sensors include a second obstacle detection sensor mounted on the side front of the vehicle, and the parking assistance device comprises a correction calculation unit that corrects the end position of the straight path based on the latest position information of the forward obstacle acquired by the first obstacle detection sensor while the vehicle is reversing along the straight path.

5. The parking assistance device according to claim 1, wherein the vehicle control unit stops the vehicle at the end of the straight path, and using the latest obstacle position information obtained by the plurality of obstacle detection sensors and the target parking position set based on the latest obstacle position information, calculates the range within the parking space that results in the same number of turns as when the vehicle moves outside the parking space by repeatedly moving forward and backward at the maximum steering angle in the direction in which the front end of the vehicle faces out of the parking space, as the initial turning position range within the space, and determines the steering angle of the circular turning path that connects the end of the straight path to a position within the initial turning position range within the space.

6. The parking assistance device according to claim 5, wherein if the vehicle control unit is unable to determine the steering angle of the circular turning path, it moves the vehicle to a position different from the end position of the straight-ahead path and attempts to determine the steering angle of the circular turning path again.

7. A parking assistance device according to claim 1, wherein the vehicle control unit stops the vehicle at the end position of the circular turning path, uses the latest obstacle position information obtained by the plurality of obstacle detection sensors and the target parking position set based on the latest obstacle position information to calculate the range within the parking space as the same number of turns as when the vehicle moves outside the parking space by repeatedly moving forward and backward at the maximum steering angle in the direction in which the front end of the vehicle faces out of the parking space from the target parking position, determines whether the end position of the circular turning path is within the range of the initial turning position within the space, and continues the parking operation of the vehicle if it is determined that the end position of the circular turning path is within the range of the initial turning position within the space.

8. A parking assistance device according to claim 7, wherein if the vehicle control unit determines that the end position of the circular turning path is not within the initial turning position range in the space, it moves the vehicle to a position different from the end position of the straight-ahead path and re-determines the steering angle of the circular turning path.

9. The parking assistance device according to claim 1, wherein the path generation unit, when determining the initial out-of-space turning position which is the position outside the parking space where the first reversal is performed after moving forward from the parking start position, determines a connection position that can be connected from the parking start position to a path consisting of one or more combinations of circular turns, clothoids, and straight paths drawn from the starting position of the straight path, within the limits of the width of the passage adjacent to the parking space and the forward area of ​​the passage, calculates the number of stationary turns from the connection position to the starting position of the straight path, and the path distance from the parking start position to the starting position of the straight path, and if there are multiple connection positions that minimize the number of stationary turns, determines the connection position that minimizes the path distance as the initial out-of-space turning position.

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