OBJECT DETECTION APPARATUS AND OBJECT DETECTION METHOD

An object detection apparatus includes a first and second transmission and reception units which are away from each other and transmit a probe wave and receive the probe wave reflected by an object, and a processing unit configured to calculate a position of the object based on a reception result. The processing unit includes a distance processing unit configured to calculate a first point based on a reception result when the first transmission and reception unit transmits the probe wave, calculate a second point based on a reception result when the second transmission and reception unit transmits the probe wave, and calculate a separation distance between the first and second points, a position calculation unit configured to calculate the position of the object based on the first and second points, and a position correction unit configured to correct the position with a correction amount corresponding to the calculated position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2022-16153, filed on Feb. 4, 2022, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an object detection apparatus and an object detection method.

BACKGROUND DISCUSSION

In the related art, there is a technique for calculating a position or the like of an object by transmitting a probe wave such as an ultrasonic wave to the object, receiving the probe wave reflected by the object, and executing various calculations.

Specifically, for example, coordinates of two points are calculated based on a trilateration method using transmission and reception results of probe waves transmitted and received by two sensors arranged by a predetermined distance from each other in a horizontal direction, and a position and a shape (a wall shape, a pole shape, or the like) of the object are determined according to a distance between the two points.

Examples of the related art include JP-2020-67431A (Reference 1).

However, in the above-described related art, accuracy of a determination result differs according to the position of the object, and there is room for improvement.

A need thus exists for an object detection apparatus and an object detection method which are not susceptible to the drawback mentioned above.

SUMMARY

According to an aspect of this disclosure, an object detection apparatus includes, for example, a first transmission and reception unit and a second transmission and reception unit which are away from each other by a predetermined distance in a horizontal direction and transmit a probe wave and receive the probe wave reflected by an object, and a processing unit configured to calculate a position of the object based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit. The processing unit includes: a distance processing unit configured to calculate a first point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the first transmission and reception unit transmits the probe wave, calculate a second point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the second transmission and reception unit transmits the probe wave, and calculate a separation distance between the first point and the second point; a position calculation unit configured to calculate the position of the object based on the first point and the second point; and a position correction unit configured to correct the position of the object with a correction amount corresponding to the calculated position of the object to correct an error that occurs when the position of the object is calculated.

According to another aspect of this disclosure, an object detection method uses, for example, an object detection apparatus including a first transmission and reception unit and a second transmission and reception unit which are away from each other by a predetermined distance in a horizontal direction and transmit a probe wave and receive the probe wave reflected by an object. The method includes: a distance processing step of calculating a first point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the first transmission and reception unit transmits the probe wave, calculating a second point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the second transmission and reception unit transmits the probe wave, and calculating a separation distance between the first point and the second point; a position calculation step of calculating a position of the object based on the first point and the second point; and a position correction step of correcting the position of the object with a correction amount corresponding to the calculated position of the object to correct an error that occurs when the position of the object is calculated.

DETAILED DESCRIPTION

Hereinafter, an exemplary embodiment of this disclosure will be disclosed. Configurations of the embodiment described below and operations, results, and effects provided by the configurations are examples. This disclosure can also be implemented by configurations other than those disclosed in the following embodiment, and at least one of various effects and derivative effects based on a basic configuration can be obtained. In the following description, for convenience of description, an elliptical arc is expressed as an “arc”.

FIG.1is a plan view of a vehicle10on which an object detection apparatus is mounted as viewed from above according to the embodiment. Directions indicated by arrows in an upper left part ofFIG.1are front-rear and left-right directions of the vehicle10.

As illustrated inFIG.1, in the vehicle10on which the object detection apparatus is mounted, a plurality of transmission and reception units11RFa,11RFb,11RBa,11RBb,11LFa,11LFb,11LBa, and11LBb included in the object detection apparatus are provided on, for example, decorative plates of doors12RF,12RB,12LF, and12LB (examples of a door that is opened and closed by rotating about a hinge as a shaft) of the vehicle10.

The transmission and reception unit11RFa is provided, for example, in the vicinity of an end portion on an opening and closing end side of the right front door12RF. A vertical position of the transmission and reception unit11RFa can be set to a lower position of the door12RF by fitting the transmission and reception unit11RFa into a decorative plate at a lower portion of the door12RF. Alternatively, the vertical position of the transmission and reception unit11RFa can also be set to a central position with respect to upper and lower ends of the door12RF, a position protruding to an outermost side of the door12RF, or the like. The transmission and reception unit11RFb is provided, for example, closer to the front of the vehicle10than the transmission and reception unit11RFa of the door12RF, and is away from the transmission and reception unit11RFa by a predetermined distance. A vertical position of the transmission and reception unit11RFb is the same as, for example, the vertical position of the transmission and reception unit11RFa. That is, the transmission and reception unit11RFb (an example of a first transmission and reception unit) and the transmission and reception unit11RFa (an example of a second transmission and reception unit) are away from each other by the predetermined distance in a horizontal direction. The transmission and reception units11LFa and11LFb are provided, for example, at positions of the left front door12LF to correspond to the transmission and reception units11RFa and11RFb respectively.

The transmission and reception unit11RBa is provided, for example, in the vicinity of an end portion on an opening and closing end side of the right rear door12RB. A vertical position of the transmission and reception unit11RBa can be set to a lower position of the door12RB by fitting the transmission and reception unit11RBa into a decorative plate at a lower portion of the door12RB. Alternatively, the vertical position of the transmission and reception unit11RBa can also be set to a center position with respect to upper and lower ends of the door12RB, a position protruding to an outermost side of the door12RB, or the like. The transmission and reception unit11RBb is provided, for example, closer to the front of the vehicle10than the transmission and reception unit11RBa of the door12RB, and is away from the transmission and reception unit11RBa by a predetermined distance. A vertical position of the transmission and reception unit11RBb is the same as, for example, the vertical position of the transmission and reception unit11RBa. That is, the transmission and reception unit11RBb and the transmission and reception unit11RBa are away from each other by the predetermined distance in the horizontal direction. The transmission and reception units11LBa and11LBb are provided, for example, at positions of the left rear door12LB to correspond to the transmission and reception units11RBa and11RBb respectively.

Hereinafter, each of the plurality of transmission and reception units11RFa,11RFb,11RBa,11RBb,11LFa,11LFb,11LBa, and11LBb are simply referred to as a transmission and reception unit11or the like when not particularly distinguished from each other. In addition, each of the plurality of doors12RF,12RB,12LF, and12LB are simply referred to as a door12or the like when not particularly distinguished from each other.

The transmission and reception unit11is a sensor or a sonar that transmits a probe wave such as an ultrasonic wave. The transmission and reception unit11also functions as a receiver that receives the probe wave reflected by an object. The transmission and reception unit11transmits and receives the probe wave to and from the vicinity of door12to detect the object present in the vicinity of the door12.

In the vehicle10on which the object detection apparatus is mounted, a plurality of door opening degree adjustment units13RF,13RB,13LF, and13LB included in the object detection apparatus are also provided, for example, inside outer panels of the doors12RF,12RB,12LF, and12LB of the vehicle10respectively.

The door opening degree adjustment unit13RF is provided, for example, in the vicinity of an end portion on a hinge side of the right front door12RF. The door opening degree adjustment unit13RB is provided, for example, in the vicinity of an end portion on a hinge side of the right rear door12RB. The door opening degree adjustment unit13LF is provided, for example, in the vicinity of an end portion on a hinge side of the left front door12LF. The door opening degree adjustment unit13LB is provided, for example, in the vicinity of an end portion on a hinge side of the left rear door12LB.

Hereinafter, each of the plurality of door opening degree adjustment units13RF,13RB,13LF, and13LB will be simply referred to as a door opening degree adjustment unit13or the like when not particularly distinguished from each other.

When an object that may be an obstacle is present in the vicinity of any of the doors12, the door opening degree adjustment unit13adjusts an opening degree of the door12to avoid a collision between the door12and the object.

FIG.2is a block diagram illustrating a hardware configuration of an object detection apparatus1according to the embodiment. The object detection apparatus1detects the object in the vicinity of the doors12of the vehicle10based on reception results received by the transmission and reception units11or the like. When the object that may be an obstacle is detected, the object detection apparatus1avoids the collision with the object using the door opening degree adjustment unit13.

As illustrated inFIG.2, the object detection apparatus1includes the plurality of transmission and reception units11RFa,11RFb,11RBa,11RBb,11LFa,11LFb,11LBa, and11LBb, the plurality of door opening degree adjustment units13RF,13RB,13LF, and13LB, an object detection unit20, and an in-vehicle network20e.

The plurality of transmission and reception units11are connected to the in-vehicle network20eand transmit transmission and reception information to the object detection unit20via the in-vehicle network20e. A plurality of door opening degree adjustment units13are connected to the in-vehicle network20eand are controlled by the object detection unit20via the in-vehicle network20eto adjust opening degrees of the doors12.

The object detection unit20determines presence of the object and a position of the object based on the transmission and reception information acquired from the plurality of transmission and reception units11. The object detection unit20outputs information on the detected object to the door opening degree adjustment units13to prevent the collision with the doors12.

The object detection unit20is a computer including a microcomputer such as an electronic control unit (ECU). The object detection unit20includes a central processing unit (CPU)20a, a read only memory (ROM)20b, a random access memory (RAM)20c, and a solid state drive (SSD)20d. The CPU20a, the ROM20b, and the RAM20cmay be integrated in the same package.

The CPU20ais an example of a hardware processor, reads a program stored in a non-volatile storage device such as the ROM20b, and executes various calculation processing and control according to the program.

The ROM20bstores programs, parameters necessary for executing the programs, and the like. The RAM20ctemporarily stores various data used in the calculation executed by the CPU20a. The SSD20dis a rewritable non-volatile storage device and maintains data even when a power supply of the object detection unit20is turned off.

The in-vehicle network20eis, for example, a controller area network (CAN). The in-vehicle network20eelectrically connects the plurality of transmission and reception units11, the plurality of door opening degree adjustment units13, and the object detection unit20so as to be able to transmit and receive signals and information to and from each other.

FIG.3is a block diagram illustrating functions of the object detection apparatus1according to the embodiment. As illustrated inFIG.3, the object detection unit20of the object detection apparatus1includes a processing unit21and a storage unit22.

The storage unit22stores a program executed by the processing unit21and data necessary for executing the program. For example, the storage unit22stores an object detection program executed by the processing unit21. The storage unit22stores numerical data necessary for executing the object detection program. In addition, the storage unit22stores door trajectory data necessary for executing the object detection program.

The processing unit21calculates the position of the object based on the reception results received by the plurality of transmission and reception units11. The processing unit21is implemented, for example, as a function of the CPU20a. The processing unit21includes a distance processing unit211, an object determination unit212, a reflection intensity processing unit213, a position correction unit214, a collision determination unit215, and a door opening degree control unit216. The processing unit21functions as the units211to216by, for example, reading the object detection program stored in the storage unit22. A part or all of the units211to216may be implemented by hardware such as a circuit including an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

Hereinafter, when examples are provided, the transmission and reception units11RFa and11RFb are mainly taken as examples of the plurality of transmission and reception units11, and the same applies to other transmission and reception units11.

The distance processing unit211calculates a first point based on a reception result received by the transmission and reception unit11RFa and a reception result received by the transmission and reception unit11RFb when the transmission and reception unit11RFa transmits a probe wave, and calculates a second point based on a reception result received by the transmission and reception unit11RFa and a reception result received by the transmission and reception unit11RFb when the transmission and reception unit11RFb transmits a probe wave. The distance processing unit211calculates a separation distance between the first point and the second point. Further, the distance processing unit211determines whether the separation distance is equal to or greater than a predetermined separation distance threshold.

The object determination unit212(an example of a position calculation unit and a shape determination unit) determines the position, an outer shape, and the like of the object based on information calculated by the distance processing unit211. For example, the object determination unit212calculates the position of the object based on the first point and the second point. The object determination unit212determines whether the object has a wall shape or a pole shape according to the separation distance.

The reflection intensity processing unit213calculates a reflection intensity representing an intensity of probe waves received by the transmission and reception unit11RFa and the transmission and reception unit11RFb. The reflection intensity processing unit213determines whether the reflection intensity is equal to or greater than a predetermined reflection intensity threshold.

The position correction unit214corrects the position of the object with a correction amount according to the calculated position of the object. The position correction unit214sets the correction amount to be larger, for example, as the calculated position of the object is closer to positions of the transmission and reception unit11RFb and the transmission and reception unit11RFa (for example, an intermediate position therebetween) (to be described in detail inFIG.14later).

In addition, the position correction unit214sets the correction amount to be larger, for example, as the calculated position of the object is closer to a position of the hinge of the door12(to be described in detail inFIGS.15A and15Blater).

Further, the position correction unit214sets the correction amount to be larger, for example, when the object determination unit212determines that the object has a pole shape and the reflection intensity calculated by the reflection intensity processing unit213exceeds the predetermined reflection intensity threshold than when the reflection intensity does not exceed the predetermined reflection intensity threshold (to be described in detail inFIG.16later).

In addition, the position correction unit214sets the correction amount to be larger, for example, when at least one of the probe waves transmitted by the transmission and reception unit11RFb and the transmission and reception unit11RFa is not received by the transmission and reception unit11RFb or the transmission and reception unit11RFa than when all of the probe waves are received.

When the object that may be an obstacle is detected in the vicinity of any of the doors12, the collision determination unit215determines whether a collision may occur between the door12and the object when the door12is opened. For example, the collision determination unit215determines whether the object is present in a region surrounded by a fully closed position of the door12, a fully opened position of the door12, and a trajectory during opening and closing of the door12, and calculates a collision position between the object and the door12when the object is present in the region.

When the collision position between the door12and the object is calculated by the collision determination unit215, the door opening degree control unit216controls the door opening degree adjustment unit13to limit the opening degree of the door12based on the collision position such that the door12is stopped right before the collision position.

Next, a method for detecting an object using the object detection apparatus1will be described in detail with reference toFIG.4and subsequent drawings.FIG.4is a diagram illustrating a functional outline of the plurality of transmission and reception units11according to the embodiment. As illustrated inFIG.4, each of the plurality of transmission and reception units11radially transmits the probe wave toward the outside of the door12and receives the probe wave toward the transmission and reception unit itself. At this time, among the plurality of transmission and reception units11, transmission and reception units11provided on the same door12are interlocked with each other as a pair. For example, the two transmission and reception units11RFa and11RFb provided on the door12RF illustrated inFIG.4operate in cooperation with each other. Accordingly, an object in the vicinity of the door12RF is detected, and a collision with the object is avoided.

Specifically, the transmission and reception units11RFa and11RFb alternately repeat a period in which each of the transmission and reception units11RFa and11RFb transmits and receives the probe wave and a period in which each of the transmission and reception units11RFa and11RFb only receives the probe wave. At this time, the transmission and reception unit11RFa transmits and receives the probe wave during a period in which the transmission and reception unit11RFb receives the probe wave. In addition, the transmission and reception unit11RFa only receives the probe wave during a period in which the transmission and reception unit11RFb transmits and receives the probe wave. The transmission and reception unit11RFb transmits and receives the probe wave during a period in which the transmission and reception unit11RFa receives the probe wave. In addition, the transmission and reception unit11RFb only receives the probe wave during a period in which the transmission and reception unit11RFa transmits and receives the probe wave. These states are illustrated inFIGS.5A and5B.

FIGS.5A and5Bare schematic diagrams illustrating states in which the plurality of transmission and reception units11RFa and11RFb perform transmission and reception according to the embodiment. InFIGS.5A and5B, an object30wsuch as a wall is present in the vicinity of the door12RF and is parallel to the door12RF.

FIG.5Aillustrates a state in which the transmission and reception unit11RFa performs transmission and reception and the transmission and reception unit11RFb only performs reception. During this period, the transmission and reception units11RFa and11RFb receive various probe waves reflected by the surrounding object30wor the like. When receiving information of the various probe waves as the transmission and reception information, the distance processing unit211of the processing unit21included in the object detection unit20determines that certain object30wis present in the vicinity of the door12RF. Then, the distance processing unit211extracts the probe waves first received by the transmission and reception units11RFa and11RFb from the various received probe waves.

As illustrated inFIG.5A, the transmission and reception unit11RFa first receives a probe wave T11which is transmitted toward a position closest to the transmission and reception unit11RFa in the wall-shaped object30wand reflected toward the transmission and reception unit11RFa. The distance processing unit211obtains a distance D11between the transmission and reception unit11RFa and the object30wbased on the detected probe wave T11. The distance D11is a value half of a numerical value obtained by multiplying a time, by a sound velocity, from the transmission of the probe wave to the reception of the probe wave T11by the transmission and reception unit11RFa. However, with only such information, a direction in which the object30wis present cannot be identified. Therefore, the object determination unit212calculates a virtual arc A11away from the transmission and reception unit11RFa by the distance D11, and assumes that the object30wis present at least at any position on the arc A11.

The transmission and reception unit11RFb first receives a probe wave T12, which reaches the transmission and reception unit11RFb through a shortest path among paths from the transmission and reception unit11RFa to the transmission and reception unit11RFb via the object30w. Based on the detected probe wave T12, the distance processing unit211obtains a length of two sides of a triangle having the transmission and reception units11RFa and11RFb as two vertices and having a third vertex on the object30w, that is, a shortest distance D12=D13+D32between the transmission and reception units11RFa and11RFb via the object30w. The length (D13+D32) of the two sides is a value obtained by multiplying a time, by the sound velocity, from when the transmission and reception unit11RFa transmits the probe wave to when the transmission and reception unit11RFb receives the probe wave T12. Next, the distance processing unit211calculates a position of the third vertex of the triangle having the transmission and reception units11RFa and11RFb as the two vertices. Given that a length of a side between the transmission and reception units11RFa and11RFb is known, the position of the third vertex can be obtained using a trilateration method based on the length of the two sides D13and D32. However, individual lengths D13and D32of the two sides are not known, and thus the third vertex cannot be identified as being located at one position with only such information. That is, there are a plurality of triangles each having the obtained length (D13+D32) of the two sides and having the third vertex at a different position. Therefore, the object determination unit212calculates a virtual arc A12connecting vertices P12of the plurality of triangles, and assumes that the object30wis present at least at any position on the arc A12.

Further, the object determination unit212estimates that the object30wis present at a point P1(first point) which is an intersection point of the calculated two arcs A11and A12. However, the point P1is located slightly before (closer to the door12RF) a position at which the object30wis actually present.

FIG.5Billustrates a state in which the transmission and reception unit11RFb performs transmission and reception and the transmission and reception unit11RFa only performs reception. During this period, the transmission and reception units11RFa and11RFb receive various probe waves reflected by the surrounding object30wor the like. The distance processing unit211receives the information of the various probe waves as the transmission and reception information, and extracts the probe waves first received by the transmission and reception units11RFa and11RFb from the various received probe waves.

As illustrated inFIG.5B, the transmission and reception unit11RFa first receives a probe wave T21, which reaches the transmission and reception unit11RFa through a shortest path among paths from the transmission and reception unit11RFb to the transmission and reception unit11RFa via the object30w. Based on the detected probe wave T21, the distance processing unit211obtains a length of two sides of a triangle having the transmission and reception units11RFa and11RFb as two vertices and having a third vertex on the object30w, that is, a shortest distance D21=D23+D31between the transmission and reception units11RFa and11RFb via the object30w. The length (D23+D31) of the two sides is a value obtained by multiplying a time, by the sound velocity, from when the transmission and reception unit11RFb transmits the probe wave T21to when the transmission and reception unit11RFa receives the probe wave T21. Next, the distance processing unit211calculates a position of the third vertex of the triangle having the transmission and reception units11RFa and11RFb as the two vertices. The position of the third vertex can be obtained using the trilateration method base on the length of the two sides D23and D31given that a length of the side between the transmission and reception units11RFa and11RFb is known. However, individual lengths D23and D31of the two sides are not known, and thus the position of the third vertex cannot be identified as one with only such information. That is, there are a plurality of triangles each having the obtained length (D23+D31) of the two sides and having the third vertex at a different position. Therefore, the object determination unit212calculates a virtual arc A21connecting vertices P21of the plurality of triangles, and assumes that the object30wis present at least at any position on the arc A21.

As illustrated inFIG.5B, the transmission and reception unit11RFb first receives a probe wave T22, which is transmitted toward a position closest to the transmission and reception unit11RFb in the wall-shaped object30wand reflected toward the transmission and reception unit11RFb. The distance processing unit211obtains a distance D22between the transmission and reception unit11RFb and the object30wbased on the detected probe wave T22. The distance D22is a value half of a numerical value obtained by multiplying a time, by the sound velocity, from the transmission of the probe wave T22to the reception of the probe wave T22by the transmission and reception unit11RFb. However, with only such information, a direction in which the object30wis present cannot be identified. Therefore, the object determination unit212calculates a virtual arc A22away from the transmission and reception unit11RFb by the distance D22, and assumes that the object30wis present at least at any position on the arc A22.

Further, the object determination unit212estimates that the object30wis present at a point P2(second point) which is an intersection point of the calculated two arcs A21and A22. However, the point P2is located slightly before (closer to the door12RF) the position at which the object30wis actually present.

As described above, the two points P1and P2are obtained as positions at which the object30wis present. When a separation distance between the points P1and P2is equal to or greater than a predetermined value, that is, when the points P1and P2are sufficiently away from each other, it is understood that the object30wis an object such as a wall extending in a wide range to some extent. This state is illustrated inFIG.6.

FIG.6is a schematic diagram illustrating a state in which the object30wis determined by the object detection unit20according to the embodiment. As illustrated inFIG.6, the distance processing unit211determines whether the separation distance between the points P1and P2is equal to or greater than the predetermined value (the predetermined separation distance threshold) based on the obtained points P1and P2. The predetermined value is, for example, a threshold or the like in the numerical data stored in the storage unit22. When the separation distance between the points P1and P2is equal to or greater than the predetermined value, the object determination unit212determines that the object30wis present in parallel with the door12RF with a certain degree of extension on a line segment L12connecting the points P1and P2and line segments L1and L2obtained by extending both ends of the line segment L12.

Next, a case in which the wall-shaped object is present in an inclined manner with respect to the door12RF will be described.

FIGS.7A and7Bare schematic diagrams illustrating states in which the plurality of transmission and reception units11RFa and11RFb perform transmission and reception according to the embodiment. InFIGS.7A and7B, an object30ssuch as a wall is present in the vicinity of the door12RF and inclined with respect to the door12RF.

FIG.7Aillustrates the state in which the transmission and reception unit11RFa performs the transmission and reception and the transmission and reception unit11RFb only performs the reception. The distance processing unit211extracts the probe waves first received by the transmission and reception units11RFa and11RFb.

As illustrated inFIG.7A, the transmission and reception unit11RFa first receives the probe wave T11, which passes through a shortest path between the transmission and reception unit11RFa and the object30s. The distance processing unit211obtains the distance D11between the transmission and reception unit11RFa and the object30sbased on the detected probe wave T11. Then, the object determination unit212calculates the virtual arc A11away from the transmission and reception unit11RFa by the distance D11.

The transmission and reception unit11RFb first receives the probe wave T12, which passes through a shortest path from the transmission and reception unit11RFa to the transmission and reception unit11RFb via the object30s. Based on the detected probe wave T12, the distance processing unit211obtains the length (D12=D13+D32) of two sides of a triangle having the transmission and reception units11RFa and11RFb as two vertices and having a third vertex on the object30s. Then, the object determination unit212calculates the virtual arc A12connecting the plurality of vertices P12based on the obtained other vertices of a plurality of triangles using the trilateration method.

Further, the object determination unit212estimates that the object30sis present at the point P1which is the intersection point of the calculated two arcs A11and A12. However, the point P1is located slightly before (closer to the door12RF) a position at which the object30sis actually present.

FIG.7Billustrates the state in which the transmission and reception unit11RFb performs the transmission and reception and the transmission and reception unit11RFa only performs the reception. The distance processing unit211extracts the probe waves first received by the transmission and reception units11RFa and11RFb.

As illustrated inFIG.7B, the transmission and reception unit11RFa first receives the probe wave T21, which passes through a shortest path from the transmission and reception unit11RFb to the transmission and reception unit11RFa via the object30s. Based on the detected probe wave T21, the distance processing unit211obtains the length (D21=D23+D31) of two sides of a triangle having the transmission and reception units11RFa and11RFb as two vertices and having a third vertex on the object30s. Then, the object determination unit212calculates the virtual arc A21connecting the plurality of vertices P21based on the obtained other vertices of a plurality of triangles using the trilateration method.

The transmission and reception unit11RFb first receives the probe wave T22, which passes through a shortest path between the transmission and reception unit11RFb and the object30s. The distance processing unit211obtains the distance D22between the transmission and reception unit11RFb and the object30sbased on the detected probe wave T22. Then, the object determination unit212calculates the virtual arc A22away from the transmission and reception unit11RFb by the distance D22.

Further, the object determination unit212estimates that the object30sis present at the point P2which is the intersection point of the calculated two arcs A21and A22. However, the point P2is located slightly before (closer to the door12RF) the position at which the object30sis actually present.

FIG.8is a schematic diagram illustrating a state in which the object30sis determined by the object detection unit20according to the embodiment. When a separation distance between the obtained points P1and P2is equal to or greater than a predetermined value, the object determination unit212of the object detection unit20determines that the object30sis an object such as a wall extending in a wide range to some extent. That is, as illustrated inFIG.8, based on the obtained points P1and P2, the object determination unit212determines that the object30sis present in an inclined manner with respect to the door12RF with a certain degree of extension on the line segment L12connecting the points P1and P2and the line segments L1and L2obtained by extending both ends of the line segment L12.

Next, a case in which a pole-shaped object is present in the vicinity of the door12RF will be described.

FIGS.9A and9Bare schematic diagrams illustrating states in which the plurality of transmission and reception units11RFa and11RFb perform transmission and reception according to the embodiment. InFIGS.9A and9B, a rod-shaped object30psuch as a pole is present in the vicinity of the door12RF.

FIG.9Aillustrates the state in which the transmission and reception unit11RFa performs the transmission and reception and the transmission and reception unit11RFb only performs the reception. The distance processing unit211extracts the probe waves T11and T12first received by the transmission and reception units11RFa and11RFb.

As illustrated inFIG.9A, the distance processing unit211obtains the distance D1lbetween the transmission and reception unit11RFa and the object30pbased on the detected probe wave T11. Then, the object determination unit212calculates the virtual arc A11away from the transmission and reception unit11RFa by the distance D11.

Based on the detected probe wave T12, the distance processing unit211obtains the length (D12=D13+D32) of two sides of a triangle having the transmission and reception units11RFa and11RFb as two vertices and having a third vertex on the object30p. Then, the object determination unit212calculates the virtual arc A12connecting the vertices P12of a plurality of triangles.

Further, the object determination unit212estimates that the object30pis present at the point P1which is the intersection point of the calculated two arcs A11and A12. However, the point P1is located slightly before (closer to the door12RF) a position at which the object30pis actually present.

FIG.9Billustrates the state in which the transmission and reception unit11RFb performs the transmission and reception and the transmission and reception unit11RFa only performs the reception. The distance processing unit211extracts the probe waves T21and T22first received by the transmission and reception units11RFa and11RFb.

As illustrated inFIG.9B, based on the detected probe wave T21, the distance processing unit211obtains the length (D21=D23+D31) of two sides of a triangle having the transmission and reception units11RFa and11RFb as two vertices and having a third vertex on the object30p. Then, the object determination unit212calculates the virtual arc A21connecting the vertices P21of a plurality of triangles.

Further, the distance processing unit211obtains the distance D22between the transmission and reception unit11RFb and the object30pbased on the detected probe wave T22. Then, the object determination unit212calculates the virtual arc A22away from the transmission and reception unit11RFb by the distance D22.

Further, the object determination unit212estimates that the object30pis present at the point P2which is the intersection point of the calculated two arcs A21and A22. However, the point P2is located slightly before (closer to the door12RF) the position at which the object30pis actually present.

FIG.10is a schematic diagram illustrating a state in which the object30pis determined by the object detection unit20according to the embodiment. As illustrated inFIG.10, the separation distance between the obtained points P1and P2is less than a predetermined value. That is, the points P1and P2are fairly close to each other. Accordingly, the object determination unit212determines that the object30pis a rod-shaped object limited to a certain narrow range. Specifically, based on the obtained points P1and P2, the object determination unit212of the object detection unit20determines that the object30pis present in a limited range on the line segment L12connecting the points P1and P2.

As described above with reference toFIGS.5A to10, the object determination unit212of the object detection unit20determines the distance from the door12RF to the object, the direction, and the outer shape such as a wall shape or a pole shape of the object detected by the transmission and reception units11RFa and11RFb. The same applies to cases in which other transmission and reception units11RBa,11RBb,11LFa,11LFb,11LBa, and11LBb are used. The transmission and reception units11RBa and11RBb provided on the door12RB operate in cooperation with each other to detect an object in the vicinity of the door12RB. The transmission and reception units11LFa and11LFb provided on the door12LF operate in cooperation with each other to detect an object in the vicinity of the door12LF. The transmission and reception units11LBa and11LBb provided on the door12LB operate in cooperation with each other to detect an object in the vicinity of the door12LB. The object determination unit212determines a position, an outer shape, and the like of the object detected by each of the transmission and reception units11.

Next, a method for avoiding a collision between an object and the door12using the object detection apparatus1will be described with reference toFIGS.11A to13B. Hereinafter, an example in which a collision with an object, which is determined mainly based on operations of the transmission and reception units11RFa and11RFb, is avoided will be described, but the collision can also be avoided using the same method when other transmission and reception units11RBa,11RBb,11LFa,11LFb,11LBa, and11LBb are used.

As described above, when it is determined that an object that may be an obstacle is present in the vicinity of the door12RF, the object detection apparatus1avoids the collision according to the outer shape of the object.

FIGS.11A and11Bare schematic diagrams illustrating states in which a collision position between the object30wand the door12RF is determined by the object detection unit20according to the embodiment. InFIGS.11A and11B, it is determined that the object30wsuch as a wall is present in the vicinity of the door12RF and is parallel to the door12RF.

As illustrated inFIGS.11A and11B, the collision determination unit215determines whether a collision may occur between the door12RF and the object when the door12RF is opened. When the collision may occur between the door12RF and the object, the collision determination unit215calculates the collision position between the door12RF and the object.

Specifically, the collision determination unit215refers to the door trajectory data stored in the storage unit22, and determines whether the detected object30wis present in a region30A surrounded by a fully closed position of the door12RF, a fully opened position of the door12RF, and a trajectory during opening and closing of the door12RF. When it is determined that the object30wis a wall-shaped object, the collision determination unit215determines that the object30wis present not only on the line segment L12between the points P1and P2but also on the line segments L1and L2obtained by extending both ends of the line segment L12. Therefore, the collision determination unit215determines whether any one of the line segments L1, L12, and L2that indicate presence of the object30wis included in the region30A.

InFIG.11A, among the line segments L1, L12, and L2, the line segments L12and L2are included in the region30A. In addition, when the door12RF is opened from a fully closed state, a point P3on the line segment L12first collides with the door12RF. The collision determination unit215calculates the point P3as the collision position. When the collision determination unit215calculates the collision position between the door12RF and the object30w, the door opening degree control unit216controls the door opening degree adjustment unit13to limit the opening degree of the door12RF such that the door12RF stops right before the collision position. The line segments L1, L12, and L2are determined to be slightly closer to the door12RF than the actual position of the object30w. In consideration of this, a position at which the collision can be sufficiently avoided is a position at which the opening degree of the door12RF is limited.

InFIG.11B, none of the line segments L1, L12, and L2are included in the region30A. Therefore, the collision determination unit215does not calculate the collision position, and the door opening degree control unit216does not limit the opening degree of the door12RF. That is, the door12RF can be fully opened.

FIGS.12A and12Bare schematic diagrams illustrating states in which a collision position between the object30sand the door12RF is determined by the object detection unit20according to the embodiment. InFIGS.12A and12B, it is determined that the object30ssuch as a wall is present in the vicinity of the door12RF and inclined with respect to the door12RF.

InFIG.12A, all of the line segments L1, L12, and L2are included in the region30A. In addition, when the door12RF is opened from the fully closed state, the point P3on the line segment L1first collides with the door12RF. The collision determination unit215calculates the point P3as the collision position. The door opening degree control unit216controls the door opening degree adjustment unit13to limit the opening degree of the door12RF such that the door12RF stops right before the collision position.

InFIG.12B, none of the line segments L1, L12, and L2are included in the region30A. Therefore, the collision determination unit215does not calculate the collision position, and the door opening degree control unit216does not limit the opening degree of the door12RF.

FIGS.13A and13Bare schematic diagrams illustrating states in which a collision position between the object30pand the door12RF is determined by the object detection unit20according to the embodiment. InFIGS.13A and13B, it is determined that the rod-shaped object30psuch as a pole is present in the vicinity of the door12RF. When the object30pis a pole-shaped object, extension lines of the line segment L12are not considered, and it is determined that the object30pis present only on the line segment L12.

InFIG.13A, the line segment L12is included in the region30A. In addition, when the door12RF is opened from the fully closed state, the point P3overlapping the point P1on the line segment L12first collides with the door12RF. The collision determination unit215calculates the point P3as the collision position. The door opening degree control unit216controls the door opening degree adjustment unit13to limit the opening degree of the door12RF such that the door12RF stops right before the collision position.

InFIG.13B, the line segment L12is not included in the region30A. Therefore, the collision determination unit215does not calculate the collision position, and the door opening degree control unit216does not limit the opening degree of the door12RF.

Next, a relationship between a distance from the sensor (each of the transmission and reception units11RFa and11RFb) to the object and a detection error will be described with reference toFIG.14.FIG.14is a diagram illustrating the relationship between the distance from the sensor to the object and the detection error according to the embodiment. InFIG.14, the transmission and reception units11RFa and11RFb are indicated by “transmission and reception units S1and S2”.

The detection error occurs due to various factors. Examples of the factors include (1) to (3) as follows.

(1) Sampling Period

A sampling period is generally short to be about tens of milliseconds, and thus an error due to the sampling period occurs regarding, for example, a reception timing or the like of a probe wave.

(2) Threshold for Detecting Various Signals

For example, when a reflected wave is detected, it is determined that the reflected wave is detected not when a value of a detected signal starts to increase but when the value of the detected signal reaches a threshold, and thus an error in time accordingly occurs.

(3) Temperature and Humidity of Air

A propagation speed of the probe wave in the air varies depending on a temperature and humidity of the air.

As illustrated inFIG.14, first, it is assumed that a wall W1is present. In this case, two detection points (estimation points) when there is no detection error include a point S1(corresponding to the point P1inFIGS.5A and5B) and a point S2(corresponding to the point P2inFIGS.5A and5B). The points S1and S2and points S1ato S1dand points S2ato S2das follows, all of which correspond to the wall W1, have values of 140 or less on a horizontal axis.

The point S1ais a detection point when it is assumed that a probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S1with a delayed predetermined error time and the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S2with an earlier predetermined error time.

The point S1bis a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S1with an earlier predetermined error time and the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S2with a delayed predetermined error time.

The point S1cis a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S1with a delayed predetermined error time and the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S2with a delayed predetermined error time.

The point S1dis a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S1with an earlier predetermined error time and the probe wave is transmitted from the transmission and reception unit S1and received by the transmission and reception unit S2with an earlier predetermined error time.

The point S2ais a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S2with a delayed predetermined error time and the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S1with an earlier predetermined error time.

The point S2bis a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S2with an earlier predetermined error time and the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S1with a delayed predetermined error time.

The point S2cis a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S2with a delayed predetermined error time and the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S1with a delayed predetermined error time.

The point S2dis a detection point when it is assumed that the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S2with an earlier predetermined error time and the probe wave is transmitted from the transmission and reception unit S2and received by the transmission and reception unit S1with an earlier predetermined error time.

The same applies to walls W2to W5. In addition, it is assumed that magnitude of the error time required for transmission and reception of the probe wave is the same for all of the walls W1to W5. Then, as can be seen fromFIG.14, it is considered that a longer distance from the sensor to the object (a wall or the like) leads to a smaller error of a detection position of the object. In addition, for example, in a case of the wall W3, a range of positions at which the points S1and S2are likely to be detected is considered to be inside a region approximately surrounded by lines L. It is considered that such a region is smaller as the distance from the sensor to the object (the wall or the like) is longer. Therefore, processing of increasing the correction amount by the position correction unit214as the detection position of the object is closer to positions of the transmission and reception units S1and S2(for example, an intermediate position thereof) is effective.

Next, a relationship between a distance from a hinge of a door to an object and a degree of influence on a door opening degree limitation due to a detection error will be described with reference toFIGS.15A and15B.FIGS.15A and15Bare diagrams illustrating the relationship between the distance from the hinge of the door to the object and the degree of influence on the door opening degree limitation due to the detection error according to the embodiment.

InFIGS.15A and15B, a door D (door12), sensors X1and X2(the transmission and reception units11RFa and11RFb), and a hinge H are illustrated. InFIG.15A, one of points Y11and Y12is a true value (a detection position without error), and the other is a detection position with an error. Due to this error, an error of a length H1occurs in a portion of a trajectory E of an end portion of the door D when the door D is opened and closed.

On the other hand, inFIG.15B, points Y21and Y22are located farther from the hinge H than the points Y11and Y12inFIG.15A. A distance between the point Y21and the point Y22is equal to a distance between the points Y11and Y12. In this case, due to this error, an error of a length H2occurs in the portion of the trajectory E of the end portion of the door D when the door D is opened and closed.

As can be seen fromFIGS.15A and15B, the length H1is larger than the length H2. Therefore, processing of increasing the correction amount by the position correction unit214as the detection position of the object is closer to a position of the hinge H of the door D is effective. In other words, for example, safety when the detection position of the object is used for subsequent door opening degree control is further improved accordingly.

Next,FIGS.16A and16Bare diagrams illustrating an example of object detection according to the embodiment. InFIG.16A, it is assumed that two detection points are points Y31and Y32with respect to a position of a wall W, and a separation distance therebetween is equal to or greater than the separation distance threshold. In this case, it is determined that the object has a wall shape, and the door opening degree is limited with reference to, for example, a point E11obtained by correcting a position of an intersection point E12between extension lines of the points Y31and Y32and the trajectory E of the end portion of the door D when the door D is opened and closed. Accordingly, a collision between the door D and the wall W can be avoided.

On the other hand, inFIG.16B, it is assumed that two detection points are points Y41and Y42with respect to the position of the wall W, and a separation distance therebetween is less than the separation distance threshold. In this case, it is determined that the object has a pole shape, and the door opening degree is limited with reference to the points Y41and Y42instead of an intersection point E22between extension lines of the points Y41and Y42and the trajectory E of the end portion of the door D when the door D is opened and closed. However, in this case, the object is actually the wall W, and the door D may collide with the wall W.

In such a case, even though the object determination unit212determines that the object has a pole shape, the reflection intensity may exceed the predetermined reflection intensity threshold when the object is actually a wall. Therefore, processing of setting the correction amount, by the position correction unit214, to be larger when the object determination unit212determines that the object has a pole shape and the reflection intensity calculated by the reflection intensity processing unit213exceeds the predetermined reflection intensity threshold than when the reflection intensity does not exceed the predetermined reflection intensity threshold is effective. A point E21is a true value of the position of the object (the wall W) in the portion of the trajectory E of the end portion of the door D when the door D is opened and closed.

FIG.17is a diagram illustrating an example of the object detection according to the embodiment. The object is the wall W, and the wall W is inclined to approach a hinge H side of the door D as compared with when the wall W is parallel to the door D. In this case, Y51and Y52as two detection points are detected to be closer to the hinge H of the door D as compared with when the wall W is parallel to the door D. Therefore, even when coordinates of Y51and Y52as the two detection points are not calculated, it is possible to estimate that Y51and Y52as the two detection points are detected to be closer to the hinge H of the door D as compared with when the wall W is parallel to the door D simply by recognizing a relative positional relationship (an angle of a line connecting the two points with respect to a reference line) between Y51and Y52. Then, the correction amount can be increased by the position correction unit214.

Next, a procedure for object detection processing performed by the object detection apparatus1will be described.FIG.18is a flowchart illustrating the object detection processing performed by the object detection apparatus1according to the embodiment. In the following example, a detected object is present in a region based on a trajectory during opening and closing of a door.

First, in step S1, among the transmission and reception units11of the object detection apparatus1, the transmission and reception units11provided on the same door12alternately repeat a period in which each of the transmission and reception units11transmits and receives a probe wave and a period in which one of the transmission and reception units11only receives a probe wave.

Next, in step S2, the processing unit21determines whether four reflected waves are all received. When it is determined to be Yes, the processing proceeds to step S5, and when it is determined to be No, the processing proceeds to step S3.

In step S3, the object determination unit212calculates a position (a position of the object) at which a door opening degree is limited based on the acquired reflected wave.

Next, in step S4, the position correction unit214corrects the position with a larger correction amount than when the four reflected waves are all received.

In step S5, the object determination unit212determines whether the separation distance between the points P1and P2(seeFIGS.5A and5Band the like) is equal to or greater than the predetermined value. When it is determined to be Yes, the processing proceeds to step S6, and when it is determined to be No, the processing proceeds to step S12.

In step S6, the object determination unit212performs the following processing in consideration of a line segment connecting the points P1and P2and extension lines of the points P1and P2.

Next, in step S7, the position correction unit214determines whether a distance from positions of the points P1and P2(for example, an intermediate position thereof) to a hinge of the door is equal to or less than the predetermined value. When it is determined to be Yes, the processing proceeds to step S8, and when it is determined to be No, the processing proceeds to step S9.

In step S8, the object determination unit212calculates the position (the position of the object) at which the door opening degree is limited.

Next, in step S10, the position correction unit214corrects the position with a larger correction amount than in a case of step S11.

In step S9, the object determination unit212calculates the position (the position of the object) at which the door opening degree is limited.

Next, in step S11, the position correction unit214corrects the position with a smaller correction amount than in the case of step S10.

In step S12, the object determination unit212performs the following processing only considering the line segment connecting the points P1and P2.

In step S13, the reflection intensity processing unit213determines whether a reflection intensity is equal to or greater than the predetermined value (the predetermined reflection intensity threshold). When it is determined to be Yes, the processing proceeds to step S14, and when it is determined to be No, the processing proceeds to step S15.

In step S14, the object determination unit212calculates the position (the position of the object) at which the door opening degree is limited.

Next, in step S17, the position correction unit214corrects the position with a larger correction amount than in a case of step S18.

In step S15, the position correction unit214determines whether the distance from the positions of the points P1and P2(for example, the intermediate position thereof) to the hinge of the door is equal to or less than the predetermined value. When it is determined to be Yes, the processing proceeds to step S16, and when it is determined to be No, the processing proceeds to step S14.

In step S16, the object determination unit212calculates the position (the position of the object) at which the door opening degree is limited.

Next, in step S18, the position correction unit214corrects the position with a smaller correction amount than in the case of step S17.

After steps S10, S11, S17, S18, and S4, in step S19, the door opening degree control unit216controls the door opening degree adjustment unit13to limit the opening degree of the door12such that the door12stops right before a collision position based on the collision position between the door12and the object calculated by the collision determination unit215using the corrected position.

In this manner, according to the object detection apparatus1of the embodiment, accuracy of a determination result related to object detection can be improved by adjusting the correction amount of the position of the object according to the detection position of the object. Therefore, for example, it is possible not only to avoid a collision between the door and the object, but also to avoid a situation in which a door opening operation is stopped at a time point at which the door and the object are still far from each other.

In addition, it is possible to perform an appropriate correction according to detection characteristics that a detection error is smaller as a distance from a sensor (each of the first transmission and reception unit and the second transmission and reception unit) to the object is longer.

Further, the correction amount is set to be larger as the detection position of the object is closer to a position of the hinge, so that the safety when the detection position of the object is used for subsequent door opening degree control is further improved.

Even when it is determined that the object has a pole shape, the object may also have a wall shape when the reflection intensity exceeds the predetermined reflection intensity threshold. The correction amount is made large based on this fact so that the safety when the detection position of the object is used for the subsequent door opening degree control is further improved.

In addition, it is possible to perform an appropriate position correction according to a possibility that the object does not have a simple shape even if none of the four reflected waves are received. For example, when the object has a complicated shape, such as a bicycle, the collision between the door and the object can be more reliably avoided by correcting the position with a larger correction amount, and the safety is further improved.

Although the embodiment according to this disclosure has been described, the above embodiment and modifications are merely examples and are not intended to limit the scope of this disclosure. The embodiment described above and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and changes can be made without departing from the spirit of this disclosure. In addition, configurations and shapes of the embodiment and the modifications can be partially replaced.

For example, in the above embodiment, the object detection unit20includes, for example, one ECU, but this disclosure is not limited thereto. The object detection unit20may include a plurality of ECUs. At this time, one ECU may function as a part of the object detection unit20, and other ECUs may function as other parts of the object detection unit20.

In the above embodiment, each of the transmission and reception units11RFa and11RFb alternately repeats the period in which the transmission and reception unit11transmits and receives the probe wave and the period in which the transmission and reception unit11only receives the probe wave, but this disclosure is not limited thereto. In the above configuration, the probe waves T11, T12, T21, and T22can be detected at least once, and each of the transmission and reception units11RFa and11RFb may sequentially detect these probe waves T11, T12, T21, and T22once. Alternatively, after the transmission and reception unit11RFa continuously repeats transmission and reception a plurality of times and receives the probe waves T11and T12a plurality of times in succession, the transmission and reception unit11RFb may continuously repeat transmission and reception a plurality of times and receive the probe waves T21and T22a plurality of times in succession. Alternatively, after the transmission and reception unit11RFa continuously repeats transmission and reception a plurality of times and receives the probe waves T11and T12a plurality of times in succession, the transmission and reception unit11RFb may perform transmission and reception only once and receive the probe waves T21and T22only once. Alternatively, vice versa may be possible.

In the above embodiment, two transmission and reception units11are provided on one door12, but this disclosure is not limited thereto. For example, three or more transmission and reception units may be provided for one door. By increasing the number of transmission and reception units, it is possible to detect an object in a wider range with higher accuracy.

In the above embodiment, the plurality of transmission and reception units11are provided in the vehicle10, but this disclosure is not limited thereto. The transmission and reception units can be suitably used for, for example, all mobile objects whose surrounding environment changes constantly due to movement.

According to an aspect of this disclosure, an object detection apparatus includes, for example, a first transmission and reception unit and a second transmission and reception unit which are away from each other by a predetermined distance in a horizontal direction and transmit a probe wave and receive the probe wave reflected by an object, and a processing unit configured to calculate a position of the object based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit. The processing unit includes: a distance processing unit configured to calculate a first point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the first transmission and reception unit transmits the probe wave, calculate a second point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the second transmission and reception unit transmits the probe wave, and calculate a separation distance between the first point and the second point; a position calculation unit configured to calculate the position of the object based on the first point and the second point; and a position correction unit configured to correct the position of the object with a correction amount corresponding to the calculated position of the object to correct an error that occurs when the position of the object is calculated.

With this configuration, accuracy of a determination result related to object detection can be improved by adjusting the correction amount of the position of the object corresponding to a detection position of the object.

In the object detection apparatus, for example, the position correction unit sets the correction amount to be larger as the position at which the object is detected is closer to positions of the first transmission and reception unit and the second transmission and reception unit.

With this configuration, it is possible to perform an appropriate correction according to detection characteristics that a detection error is smaller as a distance from a sensor (each of the first transmission and reception unit and the second transmission and reception unit) to the object is longer.

In the object detection apparatus, for example, the first transmission and reception unit is provided on one of a hinge side and an opening and closing end side of a door that is opened and closed by rotating about a hinge as a shaft, and the second transmission and reception unit is provided on the other one of the hinge side and the opening and closing end side of the door. The position correction unit sets the correction amount to be larger as the position at which the object is detected is closer to a position of the hinge.

With this configuration, safety when the detection position of the object is used for subsequent door opening degree control is further improved.

In the object detection apparatus, for example, the processing unit further includes a shape determination unit configured to determine whether the object has a wall shape or a pole shape according to the separation distance, and a reflection intensity processing unit configured to calculate a reflection intensity representing an intensity of the probe wave received by each of the first transmission and reception unit and the second transmission and reception unit. The position correction unit sets the correction amount to be larger when the shape determination unit determines that the object has a pole shape and the reflection intensity calculated by the reflection intensity processing unit exceeds a predetermined reflection intensity threshold than when the reflection intensity does not exceed the predetermined reflection intensity threshold.

With this configuration, even when it is determined that the object has a pole shape, the object may also have a wall shape when the reflection intensity exceeds the predetermined reflection intensity threshold. The correction amount is made large based on this fact, and thus the safety when the detection position of the object is used for the subsequent door opening degree control is further improved.

In the object detection apparatus, for example, when at least one of probe waves transmitted by the first transmission and reception unit and the second transmission and reception unit is not received by the first transmission and reception unit or the second transmission and reception unit, the position correction unit sets the correction amount to be larger than when all of the probe waves are received.

With this configuration, it is possible to perform an appropriate correction according to a possibility that the object does not have a simple shape even if none of four reflected waves are received.

In the object detection apparatus, for example, the processing unit further includes a collision determination unit configured to determine whether the object is present in a region surrounded by a fully closed position of the door, a fully opened position of the door, and a trajectory during opening and closing of the door, and calculate a collision position between the object and the door when the object is present in the region.

With this configuration, the collision position between the object and the door can be used for various subsequent processing.

In the object detection apparatus, for example, the door is provided in a vehicle, and the processing unit further includes a door opening degree control unit configured to limit an opening degree of the door based on the collision position calculated by the collision determination unit.

With this configuration, it is possible to appropriately limit the opening degree of the door based on a highly accurate collision position.

According to another aspect of this disclosure, an object detection method uses, for example, an object detection apparatus including a first transmission and reception unit and a second transmission and reception unit which are away from each other by a predetermined distance in a horizontal direction and transmit a probe wave and receive the probe wave reflected by an object. The method includes: a distance processing step of calculating a first point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the first transmission and reception unit transmits the probe wave, calculating a second point based on a reception result received by the first transmission and reception unit and a reception result received by the second transmission and reception unit when the second transmission and reception unit transmits the probe wave, and calculating a separation distance between the first point and the second point; a position calculation step of calculating a position of the object based on the first point and the second point; and a position correction step of correcting the position of the object with a correction amount corresponding to the calculated position of the object to correct an error that occurs when the position of the object is calculated.

With this configuration, accuracy of a determination result related to object detection can be improved by adjusting the correction amount of the position of the object corresponding to a detection position of the object.