Parking assist system and parking assist method

A parking assist system includes an electronic control unit. The electronic control unit is configured to detect an obstacle. The electronic control unit is configured to determine a target position of a moving path of a vehicle. The electronic control unit is configured to determine the target position at a position at which the vehicle is spaced at least a predetermined distance from the obstacle higher than a first threshold and the vehicle overlaps with the obstacle lower than the first threshold.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2014-186825 filed on Sep. 12, 2014 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a parking assist system and a parking assist method.

2. Description of Related Art

There is known a parking assist system that determines a parking target position on the basis of detected results of ultrasonic sensors (for example, Japanese Patent Application Publication No. 2000-177512 (JP 2000-177512 A)).

SUMMARY OF THE INVENTION

It is desirable to obtain a parking assist system that is able to determine a target position at a less inconvenient position even when there is an obstacle, such as a sprag, within a parking space.

A first aspect of the invention provides a parking assist system. The parking assist system includes an electronic control unit. The electronic control unit is configured to detect an obstacle. The electronic control unit is configured to determine a target position of a moving path of a vehicle. The electronic control unit is configured to determine the target position at a position at which the vehicle is spaced at least a predetermined distance from the obstacle higher than a first threshold and the vehicle overlaps with the obstacle lower than the first threshold.

A second aspect of the invention provides a parking assist method. The parking assist method includes: detecting an obstacle; determining a target position of a moving path of a vehicle; and determining the target position at a position at which the vehicle is spaced at least a predetermined distance from the obstacle higher than a first threshold and the vehicle overlaps with the obstacle lower than the first threshold.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, an exemplary embodiment of the invention will be described. The configuration of the embodiment described below, and the operation, results and advantageous effects obtained from the configuration are illustrative. The invention may be implemented by a configuration other than the configuration that will be described in the following embodiment, and may obtain at least one of various advantageous effects based on a basic configuration or secondary advantageous effects.

A vehicle1according to the present embodiment may be, for example, an automobile that uses an internal combustion engine (not shown) as a drive source, that is, an internal combustion engine automobile, may be an automobile that uses an electric motor (not shown) as a drive source, that is, an electric automobile, a fuel-cell automobile, or the like, may be a hybrid automobile that uses both the internal combustion engine and the electric motor as drive sources, or may be an automobile including another drive source. Various transmissions may be mounted on the vehicle1. Various devices, such as system and components, required to drive an internal combustion engine or an electric motor may be mounted on the vehicle1. The system, number, layout, and the like, of a device related to driving of wheels3in the vehicle1may be variously set.

As illustrated inFIG. 1, a vehicle body2constitutes a cabin2ain which an occupant (not shown) is seated. A steering unit4, an accelerator operation unit5, a brake operation unit6, a shift operation unit7, and the like, are provided near a seat2bof a driver as an occupant inside the cabin2a. The steering unit4is, for example, a steering wheel projecting from a dashboard24. The accelerator operation unit5is, for example, an accelerator pedal located near driver's foot. The brake operation unit6is, for example, a brake pedal located near driver's foot. The shift operation unit7is, for example, a shift lever projecting from a center console. The steering unit4, the accelerator operation unit5, the brake operation unit6, the shift operation unit7, and the like, are not limited to these components.

A display device8and an audio output device9are provided inside the cabin2a. The display device8serves as a display output unit. The audio output device9serves as an audio output unit. The display device8is, for example, a liquid crystal display (LCD), an organic electroluminescent display (OELD), or the like. The audio output device9is, for example, a speaker. The display device8is, for example, covered with a translucent operation input unit10, such as a touch panel. An occupant is allowed to visually recognize an image that is displayed on the display screen of the display device8via the operation input unit10. An occupant is allowed to perform an input operation by operating the operation input unit10through touching, pressing or moving the operation input unit10with a finger, or the like, at a position corresponding to an image that is displayed on the display screen of the display device8. These display device8, audio output device9, operation input unit10, and the like, are, for example, provided in a monitor device11located at the center in the vehicle width direction, that is, transverse direction, of the dashboard24. The monitor device11may have an operation input unit (not shown), such as a switch, a dial, a joystick and a push button. An audio output device (not shown) may be provided at another position inside the cabin2a, different from the monitor device11. Audio may be output from the audio output device9of the monitor device11and another audio output device. The monitor device11is, for example, shared with a navigation system or an audio system.

A display device12different from the display device8is provided inside the cabin2a. As shown inFIG. 3, the display device12is, for example, provided in an instrument panel unit25in the dashboard24, and is located at substantially the center of the instrument panel unit25between a speed indicating unit25aand a rotation speed indicating unit25b. The size of the screen12aof the display device12is smaller than the size of the screen8aof the display device8. An image that shows information for assisting in parking the vehicle1may be mainly displayed on the display device12. The amount of information that is displayed on the display device12may be smaller than the amount of information that is displayed on the display device8. The display device12is, for example, an LCD, an OELD, or the like. Information that is displayed on the display device12may be displayed on the display device8.

As illustrated inFIG. 1andFIG. 2, the vehicle1is, for example a four-wheel vehicle, and includes two right and left front wheels3F and two right and left rear wheels3R. Each of these four wheels3may be configured to be steerable. As illustrated inFIG. 4, the vehicle1includes a steering system that steers at least two of the wheels3. The steering system13includes an actuator13aand a torque sensor13b. The steering system13is electrically controlled by an electronic control unit (ECU)14, or the like, to actuate the actuator13a. The steering system13is, for example, an electric power steering system, a steer-by-wire (SBW) system, or the like. The steering system13adds torque, that is, assist torque, to the steering unit4with the use of the actuator13ato compensate for steering force or steers the wheels3with the use of the actuator13a. In this case, the actuator13amay steer one of the wheels3or may steer a plurality of the wheels3. The torque sensor13b, for example, detects a torque that is applied to the steering unit4by a driver.

As illustrated inFIG. 2, for example, four imaging units15ato15dare provided on the vehicle body2as a plurality of imaging units15. Each of the imaging units15is, for example, a digital camera that incorporates an imaging device, such as a charge coupled device (CCD) and a CMOS image sensor (CIS). Each of the imaging units15is able to output moving image data at a predetermined frame rate. Each of the imaging units15has a wide angle lens or a fisheye lens, and is able to capture an image in, for example, the range of 140° to the range of 190° in the horizontal direction. The optical axis of each of the imaging units15is set so as to be oriented obliquely downward. Thus, each of the imaging units15sequentially captures a road surface on which the vehicle1is allowed to move and an outside environment around the vehicle body2, including an area in which the vehicle1is allowed to be parked, and outputs the captured image as captured image data.

The imaging unit15ais, for example, located at a rear end2eof the vehicle body2, and is provided at a lower wall portion of a door2hof a rear boot. The imaging unit15bis, for example, located at a right-side end2fof the vehicle body2, and is provided at a right-side door mirror2g. The imaging unit15cis, for example, located at the front of the vehicle body2, that is, a front end2cin the vehicle longitudinal direction, and is provided at a front bumper, or the like. The imaging unit15dis, for example, located at the left side of the vehicle body2, that is, a left-side end2din the vehicle width direction, and is provided at a door mirror2gthat serves as a left-side projecting portion. The ECU14is able to generate an image having a wider viewing angle or generate an imaginary bird's-eye image of the vehicle1from above by executing operation processing and image processing on the basis of the image data obtained by the imaging units15. A bird's-eye image may be referred to as plan image.

The ECU14identifies partition lines, or the like, on a road surface around the vehicle1from the images of the imaging units15, and detects (extracts) parking spaces indicated by the partition lines, or the like.

As illustrated inFIG. 1andFIG. 2, for example, four distance measuring units16ato16dand eight distance measuring units17ato17hare provided on the vehicle body2as a plurality of distance measuring units16,17. Each of the distance measuring units16,17is, for example, a sonar that emits ultrasonic wave and captures the reflected wave. The sonar may also be referred to as a sonar sensor or an ultrasonic detector. The ECU14is able to detect whether there is an object, such as an obstacle, located around the vehicle1or measure a distance to the object on the basis of the detected results of the distance measuring units16,17. That is, each of the distance measuring units16,17is an example of a detection unit that detects an object. Each of the distance measuring units17may be, for example, used to detect an object at a relatively close distance. Each of the distance measuring units16may be, for example, used to detect an object at a relatively long distance, which is distant from an object that each of the distance measuring units17detects. The distance measuring units17may be, for example, used to detect an object ahead of or behind the vehicle1. The distance measuring units16may be, for example, used to detect an object to the side of the vehicle1.

As illustrated inFIG. 4, in a parking assist system100, in addition to the ECU14, the monitor device11, the steering system13, the distance measuring units16,17, and the like, a brake system18, a steering angle sensor19, an accelerator sensor20, a shift sensor21, a wheel speed sensor22, and the like, are electrically connected to one another via an in-vehicle network23that serves as an electric communication line. The in-vehicle network23is, for example, provided as a controller area network (CAN). The ECU14is able to control the steering system13, the brake system18, and the like, by transmitting control signals through the in-vehicle network23. The ECU14is able to receive detected results of the torque sensor13b, a brake sensor18b, the steering angle sensor19, the distance measuring units16, the distance measuring units17, the accelerator sensor20, the shift sensor21, the wheel speed sensor22, and the like, and operation signals of the operation input unit10, and the like, via the in-vehicle network23.

The ECU14, for example, includes a central processing unit (CPU)14a, a read only memory (ROM)14b, a random access memory (RAM)14c, a display control unit14d, an audio control unit14e, a solid state drive or flash memory (SSD)14f, and the like. The CPU14ais, for example, able to execute various operation processing and control, such as image processing related to images that are displayed on the display devices8,12, determination of a target position of the vehicle1, computation of a moving path of the vehicle1, determination as to whether there is an interference with an object, automatic control over the vehicle1, and cancellation of automatic control. The CPU14ais able to read a program installed and stored in a nonvolatile storage device, such as the ROM14b, and execute operation processing in accordance with the program. The RAM14ctemporarily stores various pieces of data that are used for computation in the CPU14a. The display control unit14dmainly executes image processing by the use of image data obtained by the imaging units15, synthesis of image data that are displayed on the display device8, and the like, within the operation processing in the ECU14. The audio control unit14emainly processes audio data that are output from the audio output device9within the operation processing in the ECU14. The SSD14fis a rewritable nonvolatile storage unit, and is able to store data even when the power of the ECU14is turned off. The CPU14a, the ROM14b, the RAM14c, and the like, may be integrated within the same package. The ECU14may be formed of another logical operation processor, such as a digital signal processor (DSP), a logical circuit, or the like, instead of the CPU14a. A hard disk drive (HDD) may be provided instead of the SSD14f. The SSD14for the HDD may be provided separately from the ECU14. The ECU14is an example of an electronic control unit of a parking assist system.

The brake system18is, for example, an anti-lock brake system (ABS) that prevents the brake from locking up the wheels, a side slip prevention device (electronic stability control (ESC)) that prevents a side slip of the vehicle1during cornering, an electric brake system that enhances brake force (performs brake assist), a brake-by-wire (BBW), or the like. The brake system18imparts braking force to the wheels3and, by extension, the vehicle1, via the actuator18a. The brake system18is able to execute various controls by detecting locking up of the wheels by the brake, a spin of the wheels3, a sign of a side slip, and the like, from, for example, a rotation difference between the right and left wheels3. The brake sensor18bis, for example, a sensor that detects the position of a movable unit of the brake operation unit6. The brake sensor18bis able to detect the position of the brake pedal that serves as the movable unit. The brake sensor18bincludes a displacement sensor.

The steering angle sensor19is, for example, a sensor that detects a steering amount of the steering unit4, such as the steering wheel. The steering angle sensor19is, for example, provided by using a Hall element, or the like. The ECU14acquires a driver's steering amount of the steering unit4, a steering amount of each wheel3during automatic steering, or the like, from the steering angle sensor19, and executes various controls. The steering angle sensor19detects a rotation angle of a rotating portion included in the steering unit4. The steering angle sensor19is an example of an angle sensor.

The accelerator sensor20is, for example, a sensor that detects the position of a movable unit of the accelerator operation unit5. The accelerator sensor20is able to detect the position of the accelerator pedal that serves as the movable unit. The accelerator sensor20includes a displacement sensor.

The shift sensor21is, for example, a sensor that detects the position of a movable unit of the shift operation unit7. The shift sensor21is able to detect the position of a lever, an arm, a button, or the like, that serves as the movable unit. The shift sensor21may include a displacement sensor or may be provided as a switch.

The wheel speed sensor22is a sensor that detects a rotation amount or rotation speed of each wheel3per unit time. The wheel speed sensor22outputs a wheel speed pulse number, indicating the detected rotation speed, as a sensor value. The wheel speed sensor22may be, for example, provided by using a Hall element, or the like. The ECU14computes a moving amount, and the like, of the vehicle1on the basis of the sensor value acquired from the wheel speed sensor22, and executes various controls. There is a case where the wheel speed sensor22is provided in the brake system18. In this case, the ECU14acquires the detected result of the wheel speed sensor22via the brake system18.

The configurations, arrangement, electrical connection modes, and the like, of the above-described various sensors and actuators are illustrative, and may be variously set (changed).

As shown inFIG. 5, the ECU14includes an acquisition unit141, an obstacle detection unit142, a parking space detection unit143, a candidate position setting unit144, a target position determination unit145, an output information control unit146, a path calculation unit147, a guidance control unit148, an orientation setting unit150, a storage unit149, and the like. The CPU14afunctions as the acquisition unit141, the obstacle detection unit142, the parking space detection unit143, the candidate position setting unit144, the target position determination unit145, the output information control unit146, the path calculation unit147, the guidance control unit148, the orientation setting unit150, or the like, by executing a process in accordance with a corresponding program. Data that are used in operation processes of the units, data of results in operation processes, and the like, are stored in the storage unit149. At least part of the functions of the above-described units may be implemented by hardware.

The acquisition unit141acquires various pieces of data, signal, and the like. The acquisition unit141, for example, acquires data, signals, and the like, such as detected results of the sensors, input operations, input commands, and image data. The acquisition unit141is able to acquire a signal resulting from an input operation of the operation unit14g. The operation unit14gis, for example, a push button, a switch, or the like.

The obstacle detection unit142detects an obstacle that interferes with traveling of the vehicle1. The obstacle is, for example, another vehicle, a wall, a fence, a pole, a protrusion, a step, a sprag, an object, or the like. The obstacle detection unit142is able to detect whether there is an obstacle, the height of an obstacle, the size of an obstacle, and the like, by the use of various techniques. The obstacle detection unit142is, for example, able to detect an obstacle on the basis of detected results of the distance measuring units16,17. Each of the distance measuring units16,17is able to detect an object corresponding to the height of its beam and is not able to detect an object lower than the height of the beam. Thus, the obstacle detection unit142is able to detect the height of an obstacle on the basis of the detected results of the distance measuring units16,17and the heights of beams of the distance measuring units16,17. The obstacle detection unit142may detect whether there is an obstacle or the height of an obstacle on the basis of a detected result of the wheel speed sensor22or an acceleration sensor (not shown) and detected results of the distance measuring units16,17. The obstacle detection unit142may, for example, detect the height of an obstacle through image processing based on images captured by the imaging units15.

The parking space detection unit143detects a parking space that is provided as a mark or an object. The parking space is a space that is a target or reference set such that the vehicle1is parked in that place. A parking boundary is a boundary or outer periphery of the parking space, and is, for example, a partition line, a frame line, a straight line, a band, a step, an edge of any one of them, or the like. That is, the parking boundary is a mark, an object, or the like. The parking space detection unit143is, for example, able to detect a parking space and a parking boundary through image processing based on images captured by the imaging units15. The parking space detection unit143is an example of a parking boundary detection unit.

The candidate position setting unit144sets at least one candidate position that is a candidate for a target position, that is, a terminal position of a moving path of the vehicle1. The candidate position setting unit144, for example, sets a candidate position on the basis of at least one of a detected result of the obstacle detection unit142or a detected result of the parking space detection unit143.

The target position determination unit145determines a target position from among at least one candidate position. The target position determination unit145is, for example, able to determine a high-rank candidate position, that is, an upper-level candidate position, as a target position, from among at least one candidate position ranked on the basis of a predetermined condition. The target position determination unit145is, for example, able to determine a candidate position corresponding to an occupant's input operation, that is, a candidate position selected by the occupant, as a target position from among at least one candidate position.

The output information control unit146, for example, controls the display control unit14dor the audio control unit14e, by extension, the display device8, the display device12or the audio output device9, such that the display device8, the display device12or the audio output device9outputs intended information in an intended mode at each of steps, such as a start of parking assist, an end of parking assist, determination of a target position, calculation of a path and guidance control.

The path calculation unit147, for example, calculates a moving path from the current position of the vehicle1to the target position on the basis of the current position of the vehicle1, that is, the host vehicle, the determined target position, the detected obstacle, and the like.

The guidance control unit148controls the portions such that the vehicle1moves along the calculated moving path. In the vehicle1that moves by the use of creeping, or the like, without operating the accelerator pedal, the guidance control unit148is, for example, able to move the vehicle1along the moving path by controlling the steering system13in response to the position of the vehicle1. The guidance control unit148may control not only the steering system13but also a drive mechanism, such as an engine and a motor, the brake system18that serves as a braking mechanism, or the like. The guidance control unit148may, for example, inform the driver of movement of the vehicle1along the moving path through display output or audio output commensurate with the position of the vehicle1by controlling the output information control unit146, the display control unit14dor the audio control unit14e, by extension, the display device8, the display device12or the audio output device9.

The storage unit149stores data that are used in computation in the ECU14or data calculated in computation in the ECU14.

In the parking assist system100, a process is executed in accordance with the procedure illustrated inFIG. 6. Initially, the obstacle detection unit142detects an obstacle (S1), and the parking space detection unit143detects a parking space and a parking boundary (S2). Subsequently, the candidate position setting unit144sets at least one candidate position that is a candidate for a target position, that is, terminal position, of the moving path of the vehicle1on the basis of the detected results of S1and S2(S3). Subsequently, the acquisition unit141acquires an input operation that issues a command to start parking assist (S4). That is, in the present embodiment, for example, before an operation command is input, S1to S3are executed. Subsequently, the target position determination unit145determines a target position from among at least one candidate position (S5). In S5, the target position determination unit145is able to rank each of the at least one candidate position, and determine the highest-rank candidate position as the target position. Alternatively, the target position determination unit145may determine a candidate position, selected on the basis of an occupant's input operation, as the target position. Subsequently, the path calculation unit147calculates a moving path from the current position of the vehicle1to the determined target position (S6). Subsequently, the guidance control unit148controls the portions such that the vehicle1moves along the calculated moving path (S7). The target position, the moving path, or the like, may be corrected or updated as needed in the middle of movement of the vehicle1along the moving path.

As illustrated inFIG. 7, while the vehicle1is passing through a passage PS, the ECU14is able to detect obstacles B, parking boundaries D, and the like, located to the side or rear side of the vehicle1, on the basis of image data captured by the imaging units15and detected results of the distance measuring units16,17.FIG. 7illustrates captured ranges of the imaging units15and detected ranges of the distance measuring units16,17by the alternate long and two-short dashes lines; however, these are illustrative. The imaging units15, the captured ranges, the distance measuring units16,17and the detected ranges are not limited to the example shown inFIG. 7. In the drawings inFIG. 7andFIG. 10, the arrow that indicates the forward side in the vehicle longitudinal direction is affixed to the vehicle1; however, the arrow does not always indicate the traveling direction. The distance measuring units17are able to obtain detected results at the time when the vehicle1turns or reverses. The vehicle1may be referred to as host vehicle.

Next, an example of setting of a candidate position C by the candidate position setting unit144according to the present embodiment will be described with reference toFIG. 8toFIG. 11. The target position determination unit145determines a target position from among at least one candidate position C set by the candidate position setting unit144. That is, the target position determination unit145is able to determine a position set for the candidate position C as a target position but the target position determination unit145is not able to determine a position not set for the candidate position C as a target position. Thus, the following condition for setting a candidate position C is also a condition for setting a target position.

As illustrated inFIG. 8, the candidate position setting unit144sets a candidate position C such that the vehicle1is spaced at least a predetermined distance Lb from an obstacle B1of which a height h1from a road surface Rs is higher than a threshold h0. The obstacle B1is, for example, a wall, a fence, a pole, another vehicle, or the like. Thus, a situation in which the vehicle1interferes with the tall obstacle B1is prevented. The threshold h0is an example of a first threshold. The threshold h0is, for example, set to a height at which an obstacle does not interfere with the lower portion of the vehicle body, except the wheels3.

As illustrated inFIG. 9, the candidate position setting unit144is able to set a candidate position C to a position at which the vehicle1overlaps with obstacles B2to B5of which heights h2to h5are lower than the threshold h0. The obstacle B2is, for example, a sprag. The obstacle B3is, for example, a protrusion. The obstacle B4is, for example, an elevating plate for stopping a vehicle. The obstacle B5is, for example, a protrusion. Thus, a candidate position C is set while avoiding the low obstacles B2to B5, and a situation that a candidate position cannot be set at an originally available parking space or position is prevented.

FIG. 10illustrates a plan view of a detected result of the parking assist system100of the vehicle1that travels in the traveling direction V. Mutually spaced two obstacles B and mutually spaced two parking boundaries D are detected. An entrance side of a parking space is the upper side inFIG. 10.FIG. 10shows detected results at the time when the vehicle1passes by the upper side ofFIG. 10in the leftward direction (traveling direction V), so the obstacles B are, for example, detected in a downward-open inverted U shape in the drawing. Each of the obstacles B is an obstacle higher than the threshold h0. The parking boundaries D are detected from image data captured by the imaging units15. An image of each parking boundary D is detected as a linear or band-shaped area. Detected results vary depending on settings of the distance measuring units16,17and imaging units15.

The candidate position setting unit144sets a limit line L of each obstacle B at a position spaced a predetermined distance d from the outer periphery of the corresponding obstacle B substantially along the outer periphery of the corresponding obstacle B. The candidate position setting unit144sets a candidate position C within an area across the limit lines L from the corresponding obstacles B. Thus, at least the certain distance d, that is, clearance, is ensured between each obstacle B and the vehicle1located at the candidate position C.

The candidate position setting unit144sets a candidate position C such that the candidate position C does not overlap with the parking boundaries D. That is, a candidate position C is set in an area that does not overlap with the parking boundaries D, that is, an area out of the parking boundaries D, within an intended area (an area allowed to be set).

The candidate position setting unit144determines a candidate position C in the longitudinal direction of the vehicle1on the basis of the detected obstacles B and parking boundaries D. Hereinafter, for the sake of convenience of description, a direction in which the parking boundaries D extend is simply referred to as longitudinal direction (vertical direction inFIG. 10), and a direction perpendicular to the direction in which the parking boundaries D extend is simply referred to as transverse direction (horizontal direction inFIG. 10). When the parking boundaries D have not been sufficiently detected, the candidate position setting unit144sets the longitudinal direction corresponding to the longitudinal direction of the vehicle1and the transverse direction corresponding to the width direction of the vehicle1on the basis of detected obstacles B, B2, B4, and the like, and executes a similar process to the following process.

When a front end Df, that is, an entrance-side end, of each parking boundary D has been detected, the candidate position setting unit144, for example, sets a candidate position C such that a reference point Pr of the vehicle1is located at a position spaced a distance L1from the front end Df in the longitudinal direction. When no parking boundary D has been detected and the obstacles B have been detected, it is possible to similarly set a candidate position C on the basis of the obstacles B. The reference point Pr is, for example, set at a center position between the rear wheels3R of the vehicle1.

When a rear end Dr, that is, back-side end, of each parking boundary D has been detected, the candidate position setting unit144is, for example, able to set a candidate position C such that the reference point Pr of the vehicle1is located at a position spaced a distance L2from the rear end Dr in the longitudinal direction or a rear end Cr of the vehicle1is located at a position spaced a distance L3from the rear end Dr in the longitudinal direction.

The heights h2, h4of the obstacles B2, B4are detected, and are lower than the threshold h0. In this case, the candidate position setting unit144is able to set a candidate position C to a position at which the vehicle1overlaps with these obstacles B2, B4.

The candidate position setting unit144is able to determine whether the vehicle1runs over the obstacles B2, B4on the basis of relative positions of the obstacles B2, B4with respect to the positions of the parking boundaries D or obstacles B that determine a parking space or an available parking space. In the example shown inFIG. 10, a distance Lb4in the longitudinal direction from the front end Df of each parking boundary D to the obstacle B4is shorter than the overall length of the vehicle1, and is, for example, about half of the overall length. The obstacle B4located at such a position is less likely to be a sprag. Thus, for the obstacle B4of which a distance in the longitudinal direction from the front end Df of each parking boundary D falls within a range shorter than or equal to about two thirds of the length of the vehicle1and the height is lower than the threshold h0, the candidate position setting unit144is, for example, able to set a candidate position C on a side across the obstacle B4from the entrance side, that is, the back side.

In the example ofFIG. 10, a distance Lb2from the front end Df of each parking boundary D to each obstacle B2is a length close to the overall length of the vehicle1. The obstacles B2located at such a position are highly likely to be sprags. Thus, for the obstacles B2of which a distance in the longitudinal direction from the front end Df of each parking boundary D falls within a range longer than or equal to about three quarters of the length of the vehicle1and the height is lower than the threshold h0, the candidate position setting unit144may set a candidate position C on the basis of the obstacles B2. Specifically, it is possible to set a candidate position C such that the reference point Pr of the vehicle1is located a distance Lr2forward from each obstacle B2in the longitudinal direction. The distance Lr2is set on the basis of a value in a state where the rear wheels3R of the vehicle1contact the front ends of sprags.

The candidate position setting unit144is able to set a position in the vehicle width direction with respect to the obstacle B4over which the vehicle1runs. It is not desirable that the rear wheels3R of the vehicle1pass over an end Be. When the end Be of the obstacle B4in the vehicle width direction has been detected, the candidate position setting unit144, for example, sets a candidate position C such that a distance Wbe in the transverse direction between the end Be and an end Ce of the vehicle1in the vehicle width direction falls within a predetermined range in which the rear wheels3R do not overlap with the end Be or a distance Wb4in the transverse direction between the end Be and the center line CL or reference point Pr of the vehicle1falls within a predetermined range in which the rear wheels3R do not overlap with the end Be.

The candidate position setting unit144is able to set the position, that is, orientation Cv, of the vehicle1at the candidate position C. The candidate position setting unit144is, for example, able to detect an orientation at the candidate position C on the basis of at least one of the detected parking boundary D and the detected obstacle B. The orientation Cv may be, for example, set on the basis of the direction in which each parking boundary D extends, the direction along the limit line L, or the like.

The candidate position setting unit144is able to set a position, that is, orientation, with respect to the obstacles B2, B4with which the vehicle1overlaps at the candidate position C. The obstacles B2, B4are mostly installed in position corresponding to the parking space. For example, the front edge portions of the obstacles B2, B4are mostly set so as to be perpendicular to the depth direction of the parking space. Thus, the candidate position setting unit144is able to set the orientation Cv on the basis of the directions detected for the obstacles B2, B4. In the example shown inFIG. 10, the candidate position setting unit144is, for example, able to set the orientation Cv such that the orientation Cv intersects with, for example, the orientation Cv is perpendicular to, straight lines B1that are obtained through regression analysis, such as a method of least squares, on detected predetermined ranges of the front edges of the obstacles B2, B4. By setting the orientation Cv based on the detected obstacles B2, B4, such an advantageous effect that it is possible to set the orientation Cv, for example, even when the parking boundary D has not been sufficiently detected is obtained. For example, because the obstacles B2, B4intersect with (the obstacles B2, B4are perpendicular to) the orientation Cv, there is such an advantageous effect that inconvenience in the case where the wheels3run over the obstacle B4or in the case where the wheels3contact the obstacles B2reduces.

The candidate position setting unit144is, for example, able to set the orientation Cv by considering the direction in which each parking boundary D extends, the direction of the limit line L that is the direction in which the outer periphery of each obstacle B extends, the direction of each straight line B1that is the direction in which the obstacles B2, B4extend, and the like, by averaging these directions with weights assigned as needed. It is possible to change a method of calculating the orientation Cv depending on a detection situation, or the like, for example, a detected obstacle B is not used when the parking boundary D has been detected. The candidate position setting unit144is an example of a position determination unit.

There may be a case where the position of a reference point Pr1of the vehicle1for the candidate position C calculated on the basis of the parking boundaries D and the position of a reference point Pr2calculated on the basis of the obstacles B2differ from each other. In the example shown inFIG. 11, the position of the reference point Pr1that is calculated on the basis of the parking boundaries D is set to a position located the distance L1from the front end Df of each parking boundary D toward the back side in the longitudinal direction. In contrast, the position of the reference point Pr2that is calculated on the basis of the obstacles B2is set to a position located the distance Lr2from the obstacles B2toward the entrance side in the longitudinal direction. When the distance toward the back side from each front end Df to each obstacle B2is Lb2, a distance L12toward the back side from each front end Df to the reference point Pr2is L12=Lb2−Lr2, so a difference (error) δ in distance between the reference point Pr1and the reference point Pr2is δ=L1-L12. When the error δ is equal to or larger than a threshold δth, the candidate position setting unit144does not set a candidate position C. Thus, for example, a situation that the candidate position C is set to a position that deviates from the parking space may be prevented. The threshold δth is an example of a second threshold. The reference point Pr1is an example of a first candidate position. The reference point Pr2is an example of a second candidate position. The reference point Pr1may be calculated from the detected obstacles B, B1higher than the threshold h0.

Various detected results change as the vehicle1moves. For example, as the vehicle1approaches the parking space, a detection range becomes wider or detection accuracy increases. The target position determination unit145is able to update the target position and its orientation by performing similar calculation to that of the above-described candidate position setting unit144in the middle of movement of the vehicle1along the moving path to the target position determined from among the candidate positions C. When it is estimated that the vehicle1runs over the obstacle B4on the basis of detected results of the sensors, and the like, commensurate with the traveling state of the vehicle1and the operation state of the accelerator operation unit5, a target position at which the vehicle1runs over the obstacle B4may be determined.

As described above, in the present embodiment, for example, the candidate position setting unit144is able to set the candidate position C such that the vehicle1is spaced at least the predetermined distance Lb from the obstacle B1higher than the threshold h0, and is able to set the target position C at a position at which the vehicle1overlaps with the obstacles B2to B5lower than the threshold h0. Thus, according to the present embodiment, for example, even in a situation that there are the low obstacles B2to B5within the parking space, the target position may be determined at a less inconvenient position.

In the present embodiment, for example, the candidate position setting unit144is able to set the candidate position C at a position set in correspondence with the position of each obstacle B2lower than the threshold h0. Thus, for example, there are the obstacles B2, such as sprags, of which an approximate position is known in correspondence with the parking space, the target position may be determined at a less inconvenient position on the basis of the detected obstacles B2.

In the present embodiment, for example, the candidate position setting unit144is able to set the candidate position C at a position set in correspondence with the positions of the obstacles B2, B4lower than the threshold h0in the middle of movement of the vehicle1along the moving path. Thus, for example, the target position may be determined at a less inconvenient position on the basis of the detected result in the middle of the moving path.

In the present embodiment, for example, the candidate position setting unit144(position determination unit) determines the orientation Cv at the candidate position C such that the orientation Cv is set in position that intersects with the directions of the obstacles B2, B4lower than the threshold h0. Thus, for example, the target position may be determined at a less inconvenient position on the basis of the directions of the obstacles B2, B4.

In the present embodiment, for example, when a distance between the reference point Pr1(first candidate position) and the reference point Pr2(second candidate position) is longer than or equal to the threshold δth, no target position is determined. The reference point Pr1(first candidate position) is based on at least one of the detected result of the parking space detection unit143or the detected result of the obstacle detection unit142for the obstacles B, B1higher than the threshold h0. The reference point Pr2(second candidate position) is a position set in correspondence with the obstacles B2, B4lower than the threshold h0among the detected results of the obstacle detection unit142. Thus, for example, a situation that the target position is determined at a position out of the parking space may be prevented.

In the present embodiment, a parking assist method includes: detecting an obstacle; determining a target position C of a moving path of the vehicle1; and determining a candidate position C at a position at which the vehicle1is spaced at least the predetermined distance Lb from the obstacle B1higher than the threshold h0and the vehicle1overlaps with the obstacles B2to B5lower than the threshold h0. Thus, for example, even in a situation that there are low obstacles B2to B5within the parking space, the target position may be determined at a less inconvenient position.

The embodiment of the invention is illustrated above; however, the above-described embodiment is illustrative, and is not intended to limit the scope of the invention. The embodiment may be implemented in other various forms, and may be variously omitted, replaced, combined or changed without departing from the spirit of the invention. The components and shapes of each embodiment may be partially replaced. The specifications (structure, type, orientation, shape, size, length, width, height, number, arrangement, position, and the like) of each component, or the like, may be changed as needed. The invention is applicable to parking assist in parking places and parking spaces in various forms. The way of detecting or the way of setting the position and orientation of the vehicle and the candidate position and its orientation, bases for the position and orientation of the vehicle and the candidate position and its orientation, or the like, may be variously set or changed. An input signal may be based on an audio input to a microphone.