Parking assistance device

Abstract

To provide a parking support device, which in parking an own vehicle in a parking space utilizing a parking support function, can reduce inconvenience that the device wrongly guides the own vehicle to a walkway in which parking is prohibited, even in a situation where the device cannot recognize a parking frame.SOLUTION: A parking support device 1 comprises an operation support control unit 11. The operation support control unit 11 obtains environment information about a circumference of an own vehicle M from sensors 21, 26-29, determines a parking space width Wp between parked vehicles Pv parked in a parking lot on the basis of the environment information, and compares the parking space width Wp with a required parking width Ws of a virtual parking frame 41 that is required in parking the own vehicle M, which when the parking space width Wp is larger than the required parking width Ws, sets the virtual parking frame 41 in the parking space, and when the number ns of marks 51 of shoes in the virtual parking frame 41 is above a threshold nso, determines that the virtual parking frame is highly likely to be a walkway and therefore does not guide the own vehicle to the walkway.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a parking assistance device that reduces the inconvenience of erroneously determining a sidewalk within a parking lot as a parking space in a parking lot where parking frames drawn on the road surface cannot be recognized. [Background technology]

[0002] A parking assistance device that assists a driver in parking a vehicle within a parking space set in a parking lot and reduces the burden on the driver has been known. In this type of parking assistance device, while the driver is operating the vehicle within the parking lot, a control unit detects available parking space candidates and displays the candidate parking spaces on a monitor. The driver selects a desired parking space from the displayed candidate parking spaces.

[0003] Then, the control unit sets a parking guidance route for parking the vehicle in the parking space selected by the driver, and guides the vehicle to the parking space along the parking guidance route. Alternatively, the driver operates the vehicle and parks it in the parking space along the parking guidance route displayed on the monitor.

[0004] In the above-mentioned conventional parking assistance device, when parking the vehicle in a parking space, first, it detects a parking space that can be parked. Therefore, if the road surface of the parking lot is covered with snow or mud remaining after flooding, and the parking space drawn on the road surface cannot be recognized, it becomes difficult for the parking assistance device to construct a parking guideway that leads the vehicle to the parking space.

[0005] A driver needs parking assistance from a parking assistance device more in poor environments where it is difficult to recognize a parking space than in good environments. For example, Patent Document 1 (JP 2006-7875 A) discloses a technology that determines whether there is a space between parallel parked vehicles where the driver's vehicle can park by first calculating the gap distance between the two parked vehicles by subtracting half the width of each parked vehicle from the distance between the centers of the two parked vehicles in the vehicle width direction, and then determining that parking is possible if this gap distance is wider than the vehicle width of the driver's vehicle plus a predetermined margin. The technology then discloses that the center of this gap processing is set to the center of the planned parking area and the driver's vehicle is guided. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-7875 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when parking one's vehicle in a parking lot of a store or the like, the parking position changes depending on the vehicles already parked there (parked vehicles), making it difficult to always park in the same place. In addition, the layout of parking spaces set up in the parking lot also differs from store to store.

[0008] Therefore, as disclosed in Cited Document 1, even if a gap distance between two parallel parked vehicles is detected that allows the vehicle to be parked, if the road surface is covered with snow or mud remaining after flooding, the parking frame drawn on the road surface cannot be recognized, and the gap may not be a parking space but a sidewalk where parking is prohibited.

[0009] The technology disclosed in the above-mentioned Cited Document 1 merely determines whether the vehicle can be parked based on the gap distance between adjacent parked vehicles, and therefore the control unit may guide the vehicle onto a sidewalk between parking spaces where parking is prohibited.

[0010] To provide a parking assistance device that can reduce the inconvenience of guiding one's own vehicle to a sidewalk where parking is prohibited by mistake, even in a situation where a parking frame cannot be recognized when one attempts to park one's own vehicle in a parking space by using a parking assistance function. [Means for solving the problem]

[0011] The present invention relates to a parking assistance device that guides a vehicle to an available parking space in a parking lot, the device comprising: an environmental information acquisition unit that acquires environmental information around the vehicle; a storage unit that stores a virtual parking frame required for parking the vehicle; a parking interval calculation unit that calculates the width of the parking space between targets based on the environmental information acquired by the environmental information acquisition unit; a parking width comparison unit that compares the width of the parking space calculated by the parking interval calculation unit with the width of the virtual parking frame stored in the storage unit; and when the parking width comparison unit determines that the width of the parking space is wider than the width of the virtual parking frame, a virtual parking frame setting unit that sets the virtual parking frame within a parking space; a shoeprint counting unit that counts the number of shoeprints within the virtual parking frame set by the virtual parking frame setting unit based on the environmental information acquired by the environmental information acquisition unit; a parking available space setting unit that compares the number of shoeprints counted by the shoeprint counting unit with a predetermined sidewalk determination threshold, and sets the parking available space in the virtual parking frame if the number of shoeprints is less than the sidewalk determination threshold; and a parking assistance unit that guides the host vehicle to the parking available space set by the parking available space setting unit. The virtual parking frame stored in the storage unit is divided into a central search area and left and right search areas sandwiching the central search area in the width direction, and the available parking space setting unit determines that the area is a sidewalk and clears the virtual parking frame when the number of shoe prints counted by the shoe print counting unit is equal to or greater than the sidewalk determination threshold and the number of shoe prints is more concentrated in the central search area than in the left and right search areas. . [Effects of the Invention]

[0012] According to the present invention, when guiding the vehicle to a parking space in a parking lot, the width of the parking space calculated based on the environmental information acquired by the environmental information acquisition unit is first compared with the width of a pre-stored virtual parking frame required to park the vehicle. If it is determined that the width of the parking space is wider than the width of the virtual parking frame, a virtual parking frame is set within the parking space, and then shoeprints within the virtual parking frame are counted. If the number of counted shoeprints is less than the sidewalk determination threshold, the virtual parking frame is set as a parking space where the vehicle can be parked, and the vehicle is guided to this parking space. Therefore, even in a situation where the parking frame cannot be recognized, the inconvenience of erroneously guiding the vehicle to a sidewalk where parking is prohibited can be eliminated. [Brief explanation of the drawings]

[0013] [Figure 1] Schematic diagram of parking assistance system [Figure 2] Flowchart showing a parking assistance control routine [Figure 3] Flowchart showing parking assistance mode execution subroutine [Figure 4] Flowchart showing the parking assistance subroutine in adverse environments (part 1) [Figure 5] Flowchart showing the parking assistance subroutine in adverse environments (part 2) [Figure 6A] An explanatory diagram when the width between the virtual parking frame of the vehicle and the adjacent parked vehicle is the same. [Figure 6B] FIG. 10 is an explanatory diagram illustrating a case where the distance between adjacent parked vehicles is wider than the virtual parking frame of the host vehicle. [Figure 6C] FIG. 10 is an explanatory diagram illustrating a case where the distance between adjacent parked vehicles is narrower than the virtual parking frame of the host vehicle. [Figure 7] Aerial view showing the status of the search for available parking spaces [Figure 8] An explanatory diagram showing available parking spaces displayed on the HMI monitor [Figure 9] Aerial view of the entire parking lot showing available parking spaces [Figure 10]A bird's-eye view showing the virtual parking frame estimated as a parking space [Figure 11] A bird's-eye view showing the state in which the set virtual parking frame is estimated to be a parking space. [Figure 12] A bird's-eye view showing the estimated state where the virtual parking space is likely to be set on the sidewalk. [Figure 13] A bird's-eye view showing the estimated state of a virtual parking space set on the sidewalk DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described below with reference to the drawings. A parking assistance device 1 shown in FIG. 1 is mounted on a host vehicle M (see FIGS. 7 and 9). The parking assistance device 1 includes a driving assistance control unit 11. The driving assistance control unit 11 is configured with a microcontroller including a CPU, RAM, ROM, a rewritable nonvolatile memory (flash memory or EEPROM), and peripheral devices. The ROM stores programs and fixed data required for the CPU to execute various processes. The RAM serves as a work area for the CPU, temporarily storing various data for the CPU. The CPU is also called an MPU (microprocessor) or a processor. A GPU (graphics processing unit) or a GSP (graph streaming processor) may be used instead of the CPU. Alternatively, a CPU, a GPU, and a GSP may be selectively combined.

[0015] When the driver sets a desired assistance mode, the driving assistance control unit 11 performs driving assistance in the corresponding assistance mode. The driving assistance control unit 11 has a driving assistance mode and a parking assistance mode as assistance modes.

[0016] In the driving assistance mode, the host vehicle M performs map matching on a road map in a road map database 22b based on host vehicle position information acquired by a GNSS sensor 22a of a map locator unit 22 (described later), and autonomously drives the host vehicle M along a predetermined target route in sections where autonomous driving is possible. In addition, in this driving assistance mode, on roads where autonomous driving is difficult, well-known adaptive cruise control (ACC), active lane keep (ALK), and lane departure prevention (LDP) controls are executed, and when the host vehicle M stays within the lane and detects a preceding vehicle, driving control is executed to follow the preceding vehicle.

[0017] On the other hand, in the parking assistance mode, when the driver selects this mode when the vehicle M enters a parking lot and drives through the parking lot by himself, the driving assistance control unit 11 searches for available parking spaces and notifies the driver. Then, when the driver selects a desired parking space from the available parking spaces, the vehicle M is automatically parked in the selected parking space. Alternatively, a parking guidance route for parking the vehicle M into the parking space is superimposed on a surrounding image and an overhead image of the vehicle M displayed on the HMI monitor 31 (described later), thereby providing parking assistance when the driver parks by himself.

[0018] In addition, the input side of the driving assistance control unit 11 is connected to sensor units that acquire driving status information (including position and direction) of the vehicle M and information on the surrounding environment of the vehicle M, which are required when executing the driving assistance mode and parking assistance mode.

[0019] In this embodiment, the sensor units required to execute each assistance mode include a forward recognition sensor 21, a map locator unit 22, an autonomous driving sensor 23, a brake sensor 24 that detects depression of the brake pedal and turns ON, a select position sensor 25 that detects the select position selected by the driver operating the select lever, a rear sensor 26 that acquires environmental information behind the host vehicle M, left and right front side sensors 27, left and right rear side sensors 28, and left and right front side recognition cameras 29. The sensors 21, 26 to 29 constitute an environmental information acquisition unit of the present invention.

[0020] The forward recognition sensor 21 is an image sensor, and in this embodiment, it has a stereo camera consisting of a main camera 21a and a sub-camera 21b, each of which uses a CCD, CMOS, or the like as an imaging element, and an image processing unit (IPU) 21c. Both cameras 21a, 21b have a predetermined baseline length and are installed horizontally, for example, above the rearview mirror at the front of the vehicle, at a position close to the windshield and equidistant to the left and right from the center in the vehicle width direction. The forward recognition sensor 21 processes images of environmental information of a predetermined area captured by both cameras 21a, 21b using the IPU 21c, and then transmits the images to the driving assistance control unit 11.

[0021] The map locator unit 22 also includes a GNSS (Global Navigation Satellite System) sensor 22a and a road map database 22b. The GNSS sensor 22a receives positioning signals transmitted from multiple positioning satellites to acquire the position coordinates of the vehicle M. The road map database 22b is a large-capacity storage medium such as an HDD, and stores road map information. The road map information stored in the road map database 22b includes road information required when executing the driving assistance mode (general roads, main roads, expressways, road shapes, road directions, number of lanes, lane widths, etc.) and static information about parking lots required when executing the parking assistance mode (entrance / exit position information, site information, etc.).

[0022] The driving assistance control unit 11 estimates the vehicle's position (current position) on the road map by map-matching the position coordinates (latitude, longitude, altitude) of the vehicle M acquired by the GNSS sensor 22a onto the road map information stored in the road map database 22b.

[0023] The autonomous driving sensor 23 is a general term for sensors required when driving the host vehicle M autonomously, and is composed of a vehicle speed sensor that detects the vehicle speed (host vehicle speed) of the host vehicle M, a yaw rate sensor that detects the yaw rate acting on the host vehicle M, a longitudinal acceleration sensor that detects longitudinal acceleration, etc.

[0024] The rear sensor 26 is configured by a combination of a monocular camera using a CCD, CMOS, or the like as an imaging element and at least one of an ultrasonic sensor, a millimeter wave radar, a microwave radar, an infrared sensor, a laser radar, a LiDAR (Light Detection and Ranging), etc. Alternatively, the rear sensor 26 may be a stereo camera consisting of a main camera and a sub-camera, similar to the above-mentioned front recognition sensor 21.

[0025] The left and right front side sensors 27 are disposed, for example, on the left and right ridges of the front bumper of the host vehicle M, respectively, and scan a fan-shaped area (scanning area) from the diagonally forward left and right sides of the host vehicle M. On the other hand, the left and right rear side sensors 28 are disposed, for example, on the left and right ridges of the rear bumper, and scan a fan-shaped area from the rear to the left and right of the host vehicle M, which cannot be scanned by the left and right front side sensors 27. Each of these side sensors 27, 28 is made up of a millimeter-wave radar, a microwave radar, a LiDAR, or the like, and receives reflected waves from a target (a parked vehicle Pv or an exterior wall in the parking assist mode) to acquire environmental information such as the distance and direction from the host vehicle M to the target (the parked vehicle Pv or the exterior wall).

[0026] Furthermore, the left and right front side recognition cameras 29 are mounted near the left and right side mirrors and recognize the presence or absence of parking frame lines, ruts, footprints, etc. on the sides of the vehicle M that cannot be captured within the angle of view of the forward recognition sensor 21. The left and right front side recognition cameras 29 are equipped with an imaging element such as a CCD or CMOS and an image processing unit, and the images of the environmental information on the front sides captured by the imaging element are processed by the image processing unit and then transmitted to the driving assistance control unit 11.

[0027] The driving assistance control unit 11 is also connected to an HMI (Human Machine Interface) monitor 31. This HMI monitor 31 displays a mode selection screen that allows the driver to select either a driving assistance mode or a parking assistance mode as an assistance mode to be executed by the driving assistance control unit 11, a parking space selection screen (see FIG. 8) that displays available parking spaces and allows the driver to select one, and the like. Incidentally, this HMI monitor 31 may also serve as a multi-information display of a combination meter or a navigation display device (navigation monitor) of a car navigation system.

[0028] Furthermore, a drive control actuator 32 and an alarm device 33 are connected to the output side of this driving assistance control unit 11. This drive control actuator 32 is a general term for a power actuator, an electric power steering (EPS) actuator, a brake actuator, etc. that assist the driving state of the host vehicle M. Here, the power actuator controls the output of a drive source such as an engine or an electric motor. The EPS actuator controls the drive of the EPS motor. Furthermore, the brake actuator adjusts the brake hydraulic pressure supplied to the brake wheel cylinders provided on each wheel. Furthermore, the alarm device 33 notifies the driver by voice of various information required when each assistance mode is being executed.

[0029] The driving assistance control unit 11 has a parking assistance control function that parks the vehicle M in a parking space on behalf of the driver, or assists the driver when the driver attempts to park the vehicle M in a parking space by driving it himself / herself. The parking assistance control executed by the driving assistance control unit 11 is specifically processed according to a parking assistance control routine shown in Fig. 2. This routine is executed at predetermined calculation intervals after the system is started up.

[0030] In this routine, first, in step S1, the vehicle position information estimated by map locator unit 22 is acquired, and then the routine proceeds to step S2, where map information on the surrounding area of the vehicle position is acquired from map locator unit 22 based on the vehicle position information.

[0031] Next, the process proceeds to step S3, where the vehicle position is matched with a surrounding map to check whether the vehicle M is entering a parking lot. If it is determined that the vehicle M is entering a parking lot, the process proceeds to step S4. If it is determined that the vehicle M is not entering a parking lot, the process exits the routine.

[0032] When the process proceeds to step S4, an audio announcement is made from the notification device 33 to the driver asking whether or not to set the assistance mode to parking assistance mode, and a parking assistance mode selection screen is displayed on the HMI monitor 31, and the process proceeds to step S5. When the process proceeds to step S5, it is determined whether or not the driver has selected the parking assistance mode, and if the driving assistance mode has been selected, the process proceeds to step S6. Furthermore, if the driver does not select the driving assistance mode even after a predetermined time has elapsed after the announcement, or if the driver selects manual driving on the HMI monitor 31, the process simply exits the routine.

[0033] When the process proceeds to step S6, the parking assistance mode is executed and the routine is exited. The parking assistance mode is executed in accordance with the parking assistance mode execution subroutine shown in Fig. 3. In this subroutine, first, in step S11, forward and forward side environment information recognized by the forward recognition sensor 21, the left and right front side sensors 27, and the left and right front side recognition cameras 29 is acquired.

[0034] Next, the process proceeds to step S12, where vehicles (parked vehicles) Pv parked on the left and right sides of the traffic lane are detected from the acquired front and front-side environmental information. That is, as shown in Fig. 7, while the host vehicle M is traveling at a low speed in the traffic lane, vehicles (parked vehicles) Pv parked side by side on the left and right sides of the traffic lane are detected based on the acquired front and front-side environmental information.

[0035] Then, the process proceeds to step S13, where it is determined whether or not there is a parking space next to the detected parked vehicle Pv. This parking space is a space for normal parking, with a predetermined parking width defined by parking frames (described later), and is a preset fixed value. If no parking space is detected, the process branches to step S14, and if a parking space is detected, the process proceeds to step S15.

[0036] When the process branches to step S14, it is checked whether the parking assistance mode has ended, and if it is determined that the mode has ended, the routine is terminated. On the other hand, if the parking assistance mode is continuing, the process returns to step S11, and the processes of steps S11 to S13 are repeated. The parking assistance mode is terminated by the driver via the HMI monitor 31 or the like. Alternatively, the parking assistance mode is automatically terminated when the driving assistance control unit 11 detects that the host vehicle M has left the parking lot.

[0037] On the other hand, when the process proceeds from step S13 to step S15, it is checked whether a parking frame drawn on the road surface to divide a parking space has been recognized. This parking frame is recognized, for example, based on the front and front side environmental information acquired by the forward recognition sensor 21, the left and right front side sensors 27, and the left and right front side recognition cameras 29, from the brightness difference between the road surface and the edge of the parking frame, or the change in intensity (reflectance) of the reflected light or reflected wave from the road surface and the parking frame.

[0038] If the driving assist control unit 11 determines that a parking space has been recognized, the process proceeds to step S16, where the parking assist process under favorable conditions is executed, and the routine ends. Note that this parking assist process under favorable conditions is the same as the conventional parking assist process in which the host vehicle M is guided to a parking space based on a parking space, and therefore a description thereof will be omitted.

[0039] On the other hand, if it is determined that the parking space cannot be recognized, that is, the road surface is covered with snow or mud remaining after flooding, and the parking space drawn on the road surface cannot be recognized, the process proceeds to step S17, executes the parking assistance process under adverse conditions, and then exits the routine. This parking assistance process under adverse conditions is executed according to the parking assistance subroutine under adverse conditions shown in Figures 4 and 5.

[0040] In this subroutine, first, in step S21, the virtual parking frame 41 is read. The data of this virtual parking frame 41 is stored in advance as fixed data in a storage unit such as a ROM or a nonvolatile memory, and is a frame that indicates a criterion for checking whether the host vehicle M can be parked in a parking space when parking the host vehicle M in a bad environment. That is, as shown in Figures 6A to 6C, this virtual parking frame 41 is set to a rectangular parallelepiped with four sides intersecting at right angles, the front-rear direction is set to the front-rear length of the host vehicle M, and the left and right have a required parking width Ws which is the vehicle width of the host vehicle M plus a margin width.

[0041] 6A to 6C, the virtual parking frame 41 is divided into a central search area 41a and left and right search areas 41b and 41c on either side of the central search area 41a in the direction of the required parking width Ws. The width of the central search area 41a is set slightly wider than the minimum tread width of a light vehicle or the like. In each of the search areas 41a to 41c, the distribution of shoe prints 51 (see FIGS. 11 to 13) left in the parking space where the virtual parking frame 41 is set is examined to check the previous state.

[0042] That is, as shown in FIG. 11, when the ratio of the footprints 51 in the central search area 41a is small and the ratio of the footprints 51 in the left and right search areas 41b and 41c is large, it can be estimated that the footprints 51 are those when the occupant gets on and off the vehicle. Therefore, it is determined that this space is highly likely to be a parking space. On the contrary, as shown in FIG. 12, when the ratio of the footprints 51 in the central search area 41a is large and the ratio of the footprints 51 in the left and right search areas 41b and 41c is small, it can be estimated that the footprints 51 are those left by pedestrians. Therefore, it is determined that this space is highly likely to be a sidewalk. On the other hand, as shown in FIG. 14, even when the footprints 51 are distributed over the entire virtual parking frame 41, it is determined that the possibility of it being a sidewalk is high. Incidentally, the required parking width Ws and the width of the central search area 41a may be arbitrarily set by the driver in the initial settings.

[0043] Next, when proceeding to step S22, the width (parking space width) Wp of the parking space adjacent to the detected parked vehicle Pv is calculated. This parking space width Wp is based on the front and front-side environment information acquired by the front recognition sensor 21, the left and right front-side sensors 27, and the left and right front-side recognition cameras 29. It recognizes the objects such as the vehicles (parked vehicles) Pv parked in the parallel direction (see FIGS. 7 and 9) and the outer wall, etc., obtains the widths of the recognized objects (parked vehicle Pv, outer wall), and the front distance from the object to the host vehicle M, and obtains the interval between adjacent objects (parking space width Wp) from this data. Therefore, the processing in this step S22 has a function as the parking interval calculation unit of the present invention.

[0044] Thereafter, proceeding to step S23, the parking space width Wp and the required parking width Ws are compared. And when Wp≧Ws, it is determined that it is a space where the host vehicle M can be parked, and the process proceeds to step S24. Also, when Wp <Ws, it is determined that it is difficult to park the host vehicle M, and the process jumps to step S31. Incidentally, the processing in this step S23 corresponds to the parking width comparison unit of the present invention.

[0045] In step S24, a virtual parking frame 41 is set in the detected parking space, and the process proceeds to step S25. The widthwise center of this virtual parking frame 41 is set to the widthwise center of the parking space, and the edge of the virtual parking frame 41 on the vehicle entrance / exit side is set to be on the same plane as the front end of the parked vehicle Pv in front (see FIG. 7).

[0046] At this time, for example, if the distance (Wp) between the targets is more than twice the required parking width Ws, the space is set with equal intervals of virtual parking frames 41, the number of which can fit in the space. Also, if the distance between the adjacent parked vehicles Pv is wide and three or more virtual parking frames 41 can be set, the parking space is too wide, so no virtual parking frame 41 may be selected and the process may jump to step S31. The process at step S24 corresponds to the virtual parking frame setting unit of the present invention.

[0047] Proceeding to step S25, the number of shoeprints 51 (number of shoeprints) ns within the virtual parking space 41 is counted. The processing in this step corresponds to the shoeprint counting unit of the present invention. Based on the front and front-side environmental information acquired by the forward recognition sensor 21, the left and right front-side sensors 27, and the left and right front-side recognition cameras 29, the shoeprints 51 are recognized by performing well-known pattern matching processing or the like on a series of feature points indicating the outline of the shoeprint from the brightness difference occurring at the step (edge) between the snow-covered surface or the muddy surface originating from the shoeprint 51, or the change in the intensity of the reflected light or reflected wave (reflectance).

[0048] Next, proceed to step S26, where the number of shoe prints ns recognized within the virtual parking space 41 is compared with the sidewalk determination threshold nso for determining that the space is a sidewalk. If this space is a sidewalk, there is likely to be more foot traffic and therefore more scattered shoe prints 51 than if this space were a parking space. Note that instead of the number of shoe prints ns, the ratio of the number of shoe prints ns to the area of the virtual parking space 41 (ns / area) may be used, and in this case the sidewalk determination threshold nso is set to the ratio for estimating that the space is a sidewalk (for example, about 0.8).

[0049] When ns ≥ nso, it is determined that the space is likely to be a sidewalk, and the process proceeds to step S27. On the other hand, when ns < nso, it is determined that the space is likely to be a parking space, and the process branches to step S30.

[0050] When proceeding to step S27, the number of footprints ns' in the central search area 41a is extracted from the above-mentioned number of footprints ns, and the process proceeds to step S28. If the space where the virtual parking frame 41 is set is a sidewalk, it is considered that many pedestrians walk in the center of the sidewalk. On the other hand, if this space is a parking space, the footprints 51 left within the virtual parking frame 41 can be presumed to be mainly made when passengers get on and off the vehicle. In this case, the footprints are more scattered in the left and right search areas 41b and 41c than in the central search area 41a.

[0051] In step S28, the ratio (ns' / ns) of the number of footprints ns' to the number of footprints ns is compared with the sidewalk ratio determination threshold ηs (for example, about 0.4 to 0.6) representing the ratio determined to be a sidewalk in advance. When (ns' / ns) ≥ ηs, since the footprints 51 are concentrated in the central search area 41a, it cannot be clearly determined that the space is a parking space, or it is determined that the possibility of it being a sidewalk is high, and the process proceeds to step S29. On the other hand, when (ns / ns < ηs), the footprints 51 are biased towards the left and right search areas 41b and 41c, and it is determined that the possibility of it being a parking space is high, and the process branches to step S30.

[0052] When proceeding to step S29, it is presumed that the space where the virtual parking frame 41 is set is likely to be a sidewalk, the virtual parking frame 41 is cleared, and the process proceeds to step S31. On the other hand, when branching from step S26 or from step S28 to step S30, the virtual parking frame 41 set in the space is set as the parkable space Ps, and the process proceeds to step S31. Note that the processing in steps S26 to 30 corresponds to the parkable space setting unit of the present invention.

[0053] When proceeding from step S23, S29, or S30 to step S31, it is checked whether or not detection of all possible parking spaces based on the currently acquired front and front-side environmental information has been completed. If not, the process returns to step S12 in FIG. 3 to search for the next possible parking space and detect the next parked vehicle Pv. If all possible parking spaces have been detected, the process proceeds to step S32.

[0054] In step S32, the currently detected available parking space Ps is displayed on the HMI monitor 31. Fig. 8 shows an example of the available parking space Ps displayed on the HMI monitor 31. As shown by hatching in Fig. 7, when virtual parking frames 41 set in two locations, one on the near side and one on the far side of the traffic lane, are set as available parking spaces Ps, the set available parking spaces Ps are displayed in a bird's-eye view on the HMI monitor 31.

[0055] Next, the process proceeds to step S33, where the notification device 33 is activated to announce to the driver which of the available parking spaces Ps (two in FIG. 8) displayed on the HMI monitor 31 to select. Then, the process proceeds to step S34, where it is determined whether or not the driver has selected any of the available parking spaces. For example, as shown in FIG. 8, if the driver wishes to have the vehicle automatically parked in the available parking space Ps closer to the store, the driver touches the upper available parking space Ps displayed on the HMI monitor 31.

[0056] If it is determined in step S34 that the driver has selected one of the available parking spaces Ps, the process proceeds to step S35. If a predetermined time has elapsed since the announcement, or if the vehicle M has passed in front of the available parking space displayed on the HMI monitor 31, the process branches to step S36. The process in step S34 corresponds to the parking space selection unit of the present invention.

[0057] When branching to step S36, if the driver has not selected any parking space after a predetermined time has elapsed, the driving assistance control unit 11 clears all displayed parking spaces, and if the vehicle M has passed in front of a corresponding parking space, the display of that parking space is cleared and the process proceeds to step S38.

[0058] In step S38, it is checked whether the parking assist mode has ended, and if it is determined that the mode has ended, the routine is terminated. On the other hand, if the parking assist mode is still in progress, the process returns to step S11 in FIG. 3, and the next parked vehicle Pv is detected based on the newly acquired front and front-side environmental information. The parking assist mode is terminated in the same manner as the process in step S14 shown in FIG. 3 described above.

[0059] On the other hand, when the process proceeds from step S34 to step S35, the driving assistance control unit 11 sets the available parking space Ps selected by the driver (upper side in FIG. 8) as the current target parking space Pt, and proceeds to step S37. In step S37, control is executed to automatically park the host vehicle M in the target parking space Pt, and the routine ends. The processing in steps S35 and S37 corresponds to the parking assistance unit of the present invention.

[0060] That is, in the automatic parking assistance by the driving assistance control unit 11 in steps S35 and S37, first, as shown in FIG. 9, a target parking guidance path Gr is set to guide the host vehicle M to the target parking space Pt. This target parking guidance path Gr is set so that the center of the host vehicle M in the vehicle width direction coincides with the center of the target parking space Pt in the width direction. Alternatively, for example, if the parking space width Wp between the targets (parked vehicles Pv) is greater than or equal to a predetermined value (e.g., 1.5 times) the required parking width Ws of the target parking space Pt for the host vehicle M, the target parking space Pt may be set by moving the end of the required parking width Ws on the driver's seat side of the host vehicle M toward the adjacent target (parked vehicle Pv). Then, the target parking guidance path Gr may be set so that the center of the host vehicle M in the width direction is parked at the center of the target parking space Pt in the width direction.

[0061] After that, the driving support control unit 11 automatically parks the host vehicle M in the target parking space Pt as specified and then exits the routine. Note that this target parking guidance route Gr is set in accordance with the normal target parking guidance route set when a parking frame is recognized.

[0062] As a result, for example, as shown in FIG. 9, by the host vehicle M circulating in the traffic lane of the parking lot, it is possible to acquire the position information of all the parked vehicles Pv parked in the parking lot. In this case, the positions of all the parked vehicles Pv parked in the parking lot and the available parking space Ps indicated by hatching in the figure may be displayed in an overhead view on the HMI monitor 31 in the same manner as in FIG. 8 described above, so that the driver can select a desired available parking space Ps.

[0063] As described above, in the present embodiment, when attempting to automatically park the host vehicle in a parking space in a parking lot, first, it is checked whether there is a parking space for parking the host vehicle M next to the parked vehicle Pv. When a parking space is detected, it is then checked whether a parking frame that demarcates the parking space is recognized in the parking space. And when the parking frame is covered with snow, mud, etc. and cannot be recognized, parking support processing in a bad environment is executed.

[0064] In the parking support processing in a bad environment, the width Wp of the parking space next to the parked vehicle Pv is calculated, and this parking space Wp is compared with the required parking width Ws of the virtual parking frame 41 set for the host vehicle M. And when Wp≥Ws, and the number of footprint detections ns detected by the virtual parking frame 41 is less than the sidewalk determination threshold nso (ns < nso), or when the number of footprint detections ns is greater than or equal to the sidewalk determination threshold nso (ns≥nso), and the ratio of the number of footprint detections ns' in the central search area 41a to the number of footprint detections ns is ((ns' / ns) / ηs), where ηs is the sidewalk ratio determination threshold, since it is estimated that this space is likely to be a sidewalk, it is possible to reduce the inconvenience of guiding the host vehicle M to a sidewalk where parking is prohibited by mistake.

[0065] The present invention is not limited to the above-described embodiment. For example, the driver manually drives the vehicle M around a parking lot and searches for a parking space where the virtual parking frame 41 can fit while visually checking the HMI monitor 31. When the driver identifies a parking space where the virtual parking frame 41 can fit, the driver temporarily stops the vehicle M in front of the parking space and selects the driving assistance mode. This allows the driving assistance control unit 11 to check whether the vehicle M can be parked in the identified parking space, and if it is determined that parking is possible, the driving assistance control unit 11 may execute driving assistance.

[0066] Also, for example, in the processing of step S37 described above, the HMI monitor 31 may display a target parking guidance route Gr superimposed on an overhead view of the area around the parking space where the vehicle is to be parked, and the driver may drive the vehicle M to park along the target parking guidance route Gr. [Explanation of symbols]

[0067] 1...Parking assistance device, 11...Driver assistance control unit, 21...Forward recognition sensor, 21a...Main camera, 21b...Sub camera, 22...Map locator unit, 22a...GNSS sensor, 22b...Road map database, 23...Autonomous driving sensor, 24...Brake sensor, 25...Select position sensor, 26...rear sensor, 27...Left and right front side sensors, 28...Right and left rear side sensors, 29...Left and right front side recognition cameras, 31...HMI monitor, 32...Drive control actuator, 33...alarm device, 41...Virtual parking space, 41a~41c...search area, 51...shoe prints, Gr...target parking guidance route, M...own vehicle, Ps... Parking space available, Pt...target parking space, Pv...Target (parked vehicle), Wp...parking space width, Ws: Required parking width, ns,ns'...number of shoe prints, nso...sidewalk detection threshold, ηs: Sidewalk ratio determination threshold

Claims

1. A parking assistance device that guides a vehicle to an available parking space in a parking lot, an environmental information acquisition unit that acquires environmental information around the host vehicle; a storage unit that stores a virtual parking space required for parking the vehicle; a parking space calculation unit that calculates the width of a parking space between targets based on the environmental information acquired by the environmental information acquisition unit; a parking width comparison unit that compares the width of the parking space calculated by the parking interval calculation unit with the width of the virtual parking frame stored in the storage unit; a virtual parking frame setting unit that sets the virtual parking frame within the parking space when the parking width comparison unit determines that the width of the parking space is wider than the width of the virtual parking frame; a shoeprint counting unit that counts the number of shoeprints within the virtual parking frame set by the virtual parking frame setting unit based on the environmental information acquired by the environmental information acquisition unit; a parking space setting unit that compares the number of shoe prints counted by the shoe print counting unit with a predetermined sidewalk determination threshold, and sets the parking space in the virtual parking frame if the number of shoe prints is less than the sidewalk determination threshold; a parking assistance unit that guides the vehicle to the available parking space set by the available parking space setting unit; Equipped with The virtual parking frame stored in the storage unit is divided into a central search area in a width direction and left and right search areas sandwiching the central search area, The available parking space setting unit determines that the location is a sidewalk and clears the virtual parking frame when the number of shoe prints counted by the shoe print counting unit is equal to or greater than the sidewalk determination threshold and the number of shoe prints is more concentrated in the central search area than in the left and right search areas. A parking assistance device characterized by:

2. The available parking space setting unit sets the available parking space in the virtual parking frame when the number of the shoe prints counted by the shoe print counting unit is equal to or greater than the sidewalk determination threshold and the number of the shoe prints is biased toward the left and right search areas rather than the center search area.

2. The parking assistance device according to claim 1.

3. The parking assistance unit guides the vehicle so that the center of the vehicle in the width direction coincides with the center of the parking space in the width direction.

2. The parking assistance device according to claim 1.

4. The vehicle further includes a parking space selection unit that allows a driver to select one of the available parking spaces when the available parking space setting unit sets a plurality of available parking spaces, The parking assistance unit guides the vehicle to the available parking space selected by the parking space selection unit.

4. The parking assistance device according to claim 1, wherein the parking assistance device is a parking assistance device.

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