Detection device and moving body

Abstract

To provide a detection device and a moving body capable of improving object detection performance while reducing a calculation load.SOLUTION: In the detection device 40, the detection angle of the n + 1-th sensor 45 (first sensor) is narrower than the detection angle of the n-th sensor (second sensor). The angular range of the n + 1-th sensor 45 may be narrower than that of the n-th sensor. On the other hand, at a near position, Iga may be performed with a low angular resolution, and at a far position, detection needs to be performed with a high angular resolution. The n + 1-th sensor 45 can obtain a higher angular resolution than the n-th sensor because the pitch of each antenna is wide. The detection device 40 can perform detection with a low calculation load since the angle range is narrow while improving the detection performance by obtaining a high angular resolution by the n + 1 th sensor 45 for a far position. The detection device 40 can perform detection with a low calculation load by suppressing the angular resolution while securing a wide angular range by the nth sensor 45 for a close position.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a detection device and a moving object. [Background technology]

[0002] Patent Document 1 describes an RTG crane that travels on a travel path in a container yard. The RTG crane travels on the travel path and transports containers in the container yard that are placed at any position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-123367 Summary of the Invention [Problem to be solved by the invention]

[0004] In some cases, the RTG crane described above is equipped with a MIMO (Multi-Input Multi-Output) radar as a detection device that detects the distance and angle to an object in order to prevent the RTG crane from coming into contact with the object when an object is present in the travel path. The MIMO radar can adjust the angular resolution by adjusting the spacing between multiple receiving antennas that are arranged at a distance from each other. However, when attempting to achieve high angular resolution over a wide angular range, the number of receiving antennas increases, which increases the computational load.

[0005] The present disclosure aims to provide a detection device and a moving body that can improve object detection performance while reducing the computational load. [Means for solving the problem]

[0006] A detection device according to one aspect of the present disclosure includes a first sensor and a second sensor that detect the distance to an object using radio waves, and the first sensor and the second sensor each have a plurality of transmitting antennas that transmit radio waves and a plurality of receiving antennas that receive reflected radio waves, and the detection angle of the second sensor is narrower than the detection angle of the first sensor, the pitch of the transmitting antennas in the second sensor is wider than the pitch of the transmitting antennas in the first sensor, and the pitch of the receiving antennas in the second sensor is wider than the pitch of the receiving antennas in the first sensor.

[0007] In this detection device, the second sensor has a narrower detection angle than the first sensor. The second sensor can detect distant positions within a narrower angular range. Meanwhile, while low angular resolution is acceptable for close positions, high angular resolution is required for detection at distant positions. In contrast, the pitch of the transmitting antennas in the second sensor is wider than the pitch of the transmitting antennas in the first sensor. Furthermore, the pitch of the receiving antennas in the second sensor is wider than the pitch of the receiving antennas in the first sensor. Because the second sensor has a wider antenna pitch, it can achieve higher angular resolution than the first sensor. Therefore, the detection device can improve detection performance for distant positions by obtaining high angular resolution using the second sensor, while performing detection with a low computational load due to the narrower angular range. For close positions, the detection device can ensure a wide angular range using the first sensor, while performing detection with a low computational load by suppressing the angular resolution. As described above, object detection performance can be improved while reducing the computational load.

[0008] The detection device may further include an angle resolving processor that acquires detection results from the first sensor and the second sensor and performs angle resolving processing, and the angle resolving processor may identify a virtual image from the second waveform detected by the second sensor based on the first waveform detected by the first sensor and perform correction to delete the second waveform identified as a virtual image. In this case, the angle resolving processor can delete the waveform of the virtual image generated by aliasing from the second waveform without performing complex calculations.

[0009] The transmitting antennas of the first sensor and the second sensor may further include limiting means for limiting the radiation range of the radio waves. In this case, the limiting means makes it possible to easily adjust the radiation angle of the radio waves from the transmitting antennas.

[0010] The limiting means may limit the emission range so that the range is equal to or less than twice the Nyquist frequency in the angle FFT of the second sensor and equal to or greater than the Nyquist frequency. In this case, by preventing radio waves from being transmitted over an unnecessarily wide range, it is possible to prevent unnecessary reflections from containers on both sides of the roadway, etc.

[0011] The first sensor may limit its output so that the reach of its radio waves is limited to the detection distance of the second sensor. In this way, by limiting the reach of the radio waves from the first sensor to a necessary distance, it is possible to prevent unnecessary reflections from containers on both sides of the roadway, etc.

[0012] A mobile body according to one aspect of the present disclosure is a mobile body that travels on a road and is equipped with a detection device, the detection device including a first sensor and a second sensor that detect the distance to an object using radio waves, the first sensor and the second sensor each having a plurality of transmitting antennas that transmit radio waves and a plurality of receiving antennas that receive reflected radio waves, the detection angle of the second sensor being narrower than the detection angle of the first sensor, the pitch of the transmitting antennas in the second sensor being wider than the pitch of the transmitting antennas in the first sensor, and the pitch of the receiving antennas in the second sensor being wider than the pitch of the receiving antennas in the first sensor.

[0013] This moving body can provide the same functions and effects as the above-mentioned detection device. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to improve object detection performance while reducing the computational load. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 1 is a plan view showing an exemplary container terminal to which an RTG crane according to an embodiment is applied. [Figure 2] FIG. 1 is a perspective view showing an example of a group of containers to be handled and a group of adjacent containers arranged along the traveling direction of the transporting platform vehicle. [Figure 3] FIG. 1 is a perspective view showing an RTG crane according to an embodiment. [Figure 4] FIG. 2 is a schematic plan view for explaining the relationship between an RTG crane and a travel path of the RTG crane. [Figure 5] 1 is a diagram illustrating a detection device according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating a first sensor. [Figure 7] FIG. 2 is a diagram for explaining the relationship between the distances of a transmitting antenna and a receiving antenna. [Figure 8] FIG. 7 is a cross-sectional view taken along line VIII-VIII shown in FIG. [Figure 9] FIG. 2 is a schematic diagram showing each detection area of ​​the detection device. [Figure 10] FIG. 10 is an enlarged view of FIG. [Figure 11] FIG. 1 is a schematic diagram illustrating object detection. [Figure 12] FIG. 2 is a schematic diagram illustrating the processing content of a processing unit. [Figure 13] 10 is a detection device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. In addition, for ease of explanation, the drawings may be partially simplified or exaggerated, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0017] Fig. 1 is a plan view showing an exemplary container terminal 1 to which the present invention is applied. As shown in Fig. 1, the container terminal 1 is provided with a container yard 2 in which containers C are placed, a plurality of gantry cranes 3 that transfer the containers C onto a berthed container ship, a plurality of RTG cranes 10 (mobile bodies) that are placed in the container yard 2 and that handle the containers C, and a remote control room 5 that can remotely control the plurality of RTG cranes 10.

[0018] FIG. 2 is a perspective view showing a container C and an exemplary transport vehicle 20 in a container yard 2. The transport vehicle 20 is, for example, a truck, a freight car, a trailer, or an AGV (Automated Guide Vehicle). As shown in FIGS. 1 and 2, the container yard 2 is provided with a storage area where a plurality of containers are stored, and a track (track lane) for the transport vehicle 20 to travel on. The RTG crane 10 retrieves a container C from the transport vehicle 20 that has stopped at a predetermined position, and places the container C at a predetermined address in the container yard 2. The RTG crane 10 also retrieves a container C placed in the container yard 2, transfers the container C to the transport vehicle 20, and the transport vehicle 20 carries the container C out.

[0019] As an example, the container C is an ISO standard container. The container C has a long rectangular parallelepiped shape, and for example, the longitudinal length of the container C is 20 feet or more and 45 feet or less. The height of the container C is, for example, 8.5 feet or more and 9.5 feet or less. The containers C are stacked one or more levels high in the container yard 2. The number of levels in which the containers C are arranged is sometimes called a tier.

[0020] As shown in Fig. 1, the container yard 2 has a plurality of lanes L on which containers C are placed, and a plurality of RTG cranes 10 are arranged. For example, an RTG crane 10 is arranged for each lane L. The number of RTG cranes 10 arranged in a lane L may be one or more.

[0021] As shown in Fig. 2, containers C are stacked one or more levels in the container yard 2 to form a plurality of rows R. Each row R is aligned so that the longitudinal direction of the containers C constituting that row R (i.e., the containers C placed on that row R) is parallel to the longitudinal direction of the containers C constituting the other rows R.

[0022] If the longitudinal direction of the containers C aligned in the container yard 2 is defined as the X direction, the lateral direction of the containers C as the Y direction, and the height direction of the containers C as the Z direction, the container yard 2 extends on an XY plane, and the containers C are stacked in the Z direction at any position on the XY plane. The X direction coincides with the traveling direction of the RTG crane 10 in lane L. The Y direction coincides with the lateral movement direction of the RTG crane 10 in lane L.

[0023] Containers C form bays B, which are groups of multiple containers lined up in the Y direction and stacked in the Z direction. A plurality of bays B lined up in the X direction are provided in container yard 2. Bay B includes, for example, a group of containers to be handled B1, which is a target bay for handling containers C, and adjacent groups of containers B2 located on both sides of the group of containers to be handled B1 in the X direction.

[0024] FIG. 3 is a perspective view showing an example of an RTG crane 10 according to this embodiment, which is placed in a container yard 2. As shown in FIG. 3, the RTG crane 10 is a container handling crane that loads and unloads containers C. The RTG crane 10 is a type of crane known as a rubber-tired gantry crane (RTG crane). The RTG crane 10 automatically loads and unloads containers C placed in a container yard 2 at a container terminal 1, for example.

[0025] The RTG crane 10 includes, for example, a pair of legs 11, a crane girder 12 connecting the upper ends of the pair of legs 11, a trolley 13 that can travel laterally on the crane girder 12, a spreader 14 that loads and unloads containers C, and a pair of traveling sections 15A, 15B having wheels 23. The pair of legs 11 and the crane girder 12 are portal-shaped. The RTG crane 10 includes, for example, two sets of portal-shaped pairs of legs 11 and crane girders 12, and the two sets are arranged side by side in the X direction.

[0026] The trolley 13 moves laterally in the Y direction by, for example, driving a traverse motor. In this embodiment, the Y direction coincides with the traverse direction of the trolley 13. As an example, the trolley 13 has a winding drive unit 16 including a drum that rotates forward and reverse by a drum drive motor, and suspends the spreader 14 via a suspension member 18 including a wire. The suspension members 18 extend from the trolley 13 at two positions aligned in the X direction, and the spreader 14 is suspended from the suspension members 18 at two positions aligned in the X direction.

[0027] The spreader 14 is a hoisting device that suspends the container C. The spreader 14 has, for example, a rectangular shape extending in the X direction. The spreader 14 can hold the container C from above, and loads and unloads the container C by holding and lifting the container C. For example, the operation of the spreader 14 is controlled by the drive of the traverse motor and drum drive motor described above, and the drive of the traverse motor and drum drive motor is controlled by the crane control system 100.

[0028] The travelling sections 15A, 15B are mechanisms that travel along the linear travel path of the RTG crane 10. The RTG crane 10 includes a pair of travelling sections 15A, 15B provided below the legs 11 at both ends in the Y direction. Each of the travelling sections 15A, 15B includes a connecting member 21 that connects the legs 11 spaced apart in the X direction, and a plurality of wheel units 22 provided below the connecting member 21. One wheel unit 22 is provided at each end of the connecting member 21 in the X direction. The wheel unit 22 includes a plurality of wheels 23 and a wheel support section 24 that supports the wheels 23. The wheel support section 24 supports the wheels of a pair of wheels 23 aligned in the Y direction, and supports two pairs of the wheels 23 aligned in the X direction. Note that the number of wheels 23 included in each wheel unit 22 and the number of wheel units 22 included in each of the travelling sections 15A, 15B are not particularly limited.

[0029] The RTG crane 10 is equipped with a travel position detection unit 26 so that it can automatically travel straight along the travel path. The travel position detection unit 26 detects the travel position of the RTG crane 10 in the Y direction relative to the travel path. The travel position detection unit 26 is provided on the underside of the travel section 15A so as to detect guidelines 27 that are provided on the ground of the travel path so as to form a straight line in the X direction. For example, the guidelines 27 include magnets, and the travel position detection unit 26 is configured with a sensor that detects magnetic force. For example, when the travel section 15A is traveling straight in the X direction without any deviation in the Y direction relative to the travel path, the magnetic force detected by the travel position detection unit 26 is constant. In contrast, if the travel section 15A deviates in the Y direction relative to the travel path or its traveling direction is tilted relative to the travel path, the magnetic force detected by the travel position detection unit 26 will fluctuate. This makes it possible to detect deviations in the travel position of the RTG crane 10 based on the detection results of the travel position detection unit 26.

[0030] FIG. 4 is a schematic plan view illustrating the relationship between the RTG crane 10 and its travel paths RDA and RDB. As shown in FIG. 4, travel path 15A on one side in the Y direction travels on travel path RDA. Travel path 15B on the other side in the Y direction travels on travel path RDB. As a result, the RTG crane 10 travels in a direction parallel to the X direction, with travel path 15A traveling linearly on travel path RDA and travel path 15B traveling linearly on travel path RDB. In the following description, directions in absolute coordinates based on the travel paths RDA and RDB will be described using the X and Y directions, and the direction in which the RTG crane 10 travels will sometimes be referred to as the "travel direction D1." The horizontal direction perpendicular to the travel direction D1 will sometimes be referred to as the "lateral direction D2" of the RTG crane 10. The direction perpendicular to the travel direction D1 and the lateral direction D2 will sometimes be referred to as the "up-down direction D3."

[0031] The runway RDA extends linearly in the X direction at one end of the RTG crane 10 in the Y direction, adjacent to one side of the bay B for the container C in the Y direction. The runway RDB extends linearly in the X direction at the other end of the RTG crane 10 in the Y direction, adjacent to the other side of the bay B for the container C in the Y direction. A truck lane may be provided on the other side of the bay B for the container C in the Y direction. Each runway RDA is set slightly wider in the Y direction than the dimension of the runs 15A and 15B in the lateral direction D2. Here, as shown in FIG. 4, the direction toward one side in the running direction D1 is referred to as "direction A1," and the direction toward the other side is referred to as "direction A2." In this case, the runs 15A and 15B can travel in the direction A1. In this case, the direction A1 corresponds to the forward direction of the runs 15A and 15B in the running direction D1. Furthermore, the traveling sections 15A and 15B can travel in the direction A2, which corresponds to the forward direction of the traveling sections 15A and 15B in the traveling direction D1.

[0032] The RTG crane 10 includes a detection unit 30 attached to the RTG crane 10. The detection unit 30 detects objects present on the traveling side of the RTG crane 10 in the traveling direction. In this embodiment, the detection unit 30 is composed of detection units 30A, 30B, 30C, and 30D provided at four locations. When the traveling units 15A and 15B are traveling with the direction A1 as their traveling side, the detection units 30A and 30B detect objects present on the traveling side of the traveling units 15A and 15B in the traveling direction D1. The detection units 30A and 30B are attached to the direction A1 side of the traveling units 15A and 15B with respect to the crane girder 12. The detection units 30A and 30B detect objects present in detection target areas DEA and DEB extending on the traveling side (direction A1 side) in the traveling direction D1. The detection target areas DEA, DEB are set so that objects present on the running paths RDA, RDB within a predetermined distance on the direction A1 side as viewed from the running sections 15A, 15B, that is, the locations where the running sections 15A, 15B are expected to pass, can be detected.

[0033] When the traveling sections 15A, 15B are traveling with the direction A2 as their travel direction, the detection units 30C, 30D detect objects present on the travel direction of the traveling sections 15A, 15B in the traveling direction D1. The detection units 30C, 30D are attached to the crane girder 12 on the side of the traveling sections 15A, 15B facing the direction A2. The detection units 30C, 30D detect objects present in detection target areas DEC, DED extending on the travel direction (the direction A2 side) in the traveling direction D1. The detection target areas DEC, DED are set so that objects present on the travel paths RDA, RDB within a predetermined distance on the direction A2 side as seen from the traveling sections 15A, 15B can be detected.

[0034] Each of the detection units 30A, 30B, 30C, and 30D has a detection device 40. The number of detection devices 40 included in each of the detection units 30A, 30B, 30C, and 30D is not particularly limited. However, the detection device 40 according to this embodiment can ensure high angular resolution without using a triangulation method using two radar devices. Therefore, each of the detection units 30A, 30B, 30C, and 30D may have one detection device 40.

[0035] Next, the configuration of the detection device 40 will be described with reference to FIG. 5. In this embodiment, a radar device that detects the distance to an object using radio waves will be exemplified as the detection device. FIG. 5 is a diagram showing the detection device 40 according to this embodiment. As shown in FIG. 5, the detection device 40 is configured by providing elements and wiring on a substrate 50. FIG. 5 is a diagram showing the detection device 40 as viewed from the outside of the traveling section 15 in the traveling direction D1. The detection device 40 according to this embodiment is a MIMO radar that employs MIMO (Multiple Input Multiple Output) using multiple antennas on the transmitting and receiving sides. The detection device 40 includes a first sensor 45A, a second sensor 45B, a third sensor 45C, a fourth sensor 45D, and a processing unit 46. Note that in the claims, the term "first sensor" refers to a sensor with a wider detection angle than the "second sensor," and the term "second sensor" refers to a sensor with a narrower detection angle than the "first sensor." Therefore, the "first sensor" in the claims does not mean only the first sensor 45A in the embodiment, and the "second sensor" in the claims does not mean only the second sensor 45B in the embodiment. For example, if the first sensor 45A is considered to be the "first sensor," then sensors 45B, 45C, and 45D all fall under the "second sensor." If the second sensor 45B is considered to be the "first sensor," then sensors 45C and 45D all fall under the "second sensor."

[0036] The configuration of the first sensor 45A will be described with reference to FIG. 6. The first sensor 45A includes a plurality of transmitting antennas 41 and a plurality of receiving antennas 42. The plurality of transmitting antennas 41 are antennas that transmit radio waves (millimeter waves) forward. The plurality of receiving antennas 42 are antennas that receive radio waves reflected by an object. For the purpose of explanation, the first sensor 45A is assumed to have a transmitting antenna 41 identified as "Tx1," a transmitting antenna 41 identified as "Tx2," and a transmitting antenna 41 identified as "Tx3." The first sensor 45A is assumed to have a receiving antenna 42 identified as "Rx1," a receiving antenna 42 identified as "Rx2," a receiving antenna 42 identified as "Rx3," and a receiving antenna 42 identified as "Rx4."

[0037] The first sensor 45A is a continuous frequency modulation type sensor. The first sensor 45A of the continuous frequency modulation type is a type of radar that transmits radio waves, i.e., chirps, modulated so that the frequency of the waves transmitted from the transmitting antenna 41 changes continuously over time. The first sensor 45A generates an intermediate frequency signal (IF signal) based on the frequency difference between the transmitted chirp of the transmitting antenna 41 and the received chirp (the wave reflected back from the object), and calculates the distance to the object by measuring the frequency of the IF signal.

[0038] In this embodiment, the transmitting antenna 41 transmits millimeter waves as radio waves. Millimeter waves are radio waves that include a frequency band from the quasi-millimeter wave region to approximately 100 GHz. Note that quasi-millimeter waves are in a frequency band below 33 GHz and are sometimes called microwaves.

[0039] The first sensor 45A includes n transmitting antennas 41 and m receiving antennas 42. In this embodiment, the number of transmitting antennas 41 is "n = 3." The number of receiving antennas 42 is "m = 4." However, the numbers of transmitting antennas 41 and receiving antennas 42 are not particularly limited. Microstrip antennas are used as the transmitting antennas 41 and receiving antennas 42. The patch-type transmitting antennas 41 and receiving antennas 42 each have an antenna element 51 configured with a flat plate-like pattern. In the example shown in FIG. 6 , the transmitting antenna 41 has multiple (five) antenna elements 51 connected in series and arranged in the vertical direction D3. The receiving antenna 42 has multiple (three) antenna elements 51 connected in series and arranged in the vertical direction D3. However, the number of antenna elements 51 of the transmitting antenna 41 and receiving antenna 42 is not limited and may be one. Furthermore, the transmitting antenna 41 and receiving antenna 42 are not limited to microstrip antennas, and other types of antennas may be used.

[0040] Here, the distance between the antennas will be explained. The m receiving antennas 42 are arranged at a distance d from each other in the horizontal direction D2. The receiving antennas 42 are arranged in order from one side in the horizontal direction D2, namely "Rx1", "Rx2", "Rx3", and "Rx4". The n transmitting antennas 41 are arranged at a distance md from each other in the horizontal direction D2, which is the distance d multiplied by the number (m) of receiving antennas 42. In this embodiment, since m = 4, the separation distance is 4d. The transmitting antenna 41 is disposed at a position spaced downward from the receiving antenna 42. The transmitting antennas 41 are arranged in order from one side in the horizontal direction D2, namely "Tx1", "Tx2", and "Tx3".

[0041] Next, the relationship between the transmitting antenna 41 and the receiving antenna 42 will be described with reference to FIG. 7. FIG. 7 is a model diagram for explaining the relationship between the transmitting antenna 41 and the receiving antenna 42. The positional relationship between the transmitting antenna 41 and the receiving antenna 42 differs from that in FIG. 6, with the receiving antenna 42 being disposed at a position spaced apart from the transmitting antenna 41 in the horizontal direction D2. The first sensor 45A may be disposed as shown in FIG. 7. The upper part of FIG. 7 shows the actual antenna arrangement. However, the radio wave absorbing wall is omitted from the upper diagram. The lower part of FIG. 7 shows a virtual antenna arrangement. The m (four) receiving antennas 42 are referred to as an antenna group SG1. When the transmitting antenna 41 "Tx1" emits radio waves, each receiving antenna 42 in the antenna group SG1 receives the reflected wave. The combination in which the transmitting antenna 41 "Tx1" emits radio waves and the receiving antenna 42 "Rx1" receives the reflected wave is referred to as "Tx1 → Rx1." Similarly, when the transmitting antenna 41 "Tx1" emits radio waves, the receiving antennas 42 "Rx2," "Rx3," and "Rx4" also receive the reflected waves. Therefore, there are combinations such as "Tx1 → Rx2," "Tx1 → Rx3," and "Tx1 → Rx4."

[0042] In the upper diagram, when the transmitting antenna 41 of "Tx2" emits radio waves, each receiving antenna 42 of the antenna group SG1 receives the reflected wave. Therefore, the following combinations exist: "Tx2 → Rx1," "Tx2 → Rx2," "Tx2 → Rx3," and "Tx2 → Rx4." As shown in the lower diagram, a virtual antenna group SG2 having the same configuration as the antenna group SG1 is set to the right of the antenna group SG1. The distance between the receiving antenna 42 of "Rx4," which is the rightmost antenna of the antenna group SG1, and the receiving antenna 42 of "Rx1," which is the leftmost antenna of the virtual antenna group SG2, is the distance d between the antennas of the antenna group SG1. Here, the distance 4d between the transmitting antenna 41 of "Tx1" and the transmitting antenna 41 of "Tx2" is the distance d between the receiving antennas 42 of the antenna group SG1 multiplied by the number of receiving antennas 42 (four). Therefore, in the combinations of "Tx2 → Rx1," "Tx2 → Rx2," "Tx2 → Rx3," and "Tx2 → Rx4," the reception angle at which the receiving antenna 42 of the antenna group SG1 receives the reflected wave is the same as the reception angle in the combinations of the transmitting antenna 41 of "Tx1" and the virtual antenna group SG2 of "Tx1 → Rx1," "Tx1 → Rx2," "Tx1 → Rx3," and "Tx1 → Rx4." Therefore, the combination of the transmitting antenna 41 of "Tx2" and the antenna group SG1 is equivalent to the combination of the transmitting antenna 41 of "Tx1" and the virtual antenna group SG2.

[0043] A similar virtual antenna group SG3 is set to the right of the virtual antenna group SG2. In this case, in the combinations of "Tx3 → Rx1," "Tx3 → Rx2," "Tx3 → Rx3," and "Tx3 → Rx4," the reception angle at which the receiving antenna 42 of the antenna group SG1 receives the reflected wave is the same as the reception angle in the combinations of the transmitting antenna 41 of "Tx1" and the virtual antenna group SG3: "Tx1 → Rx1," "Tx1 → Rx2," "Tx1 → Rx3," and "Tx1 → Rx4." Therefore, the combination of the transmitting antenna 41 of "Tx3" and the antenna group SG1 is equivalent to the combination of the transmitting antenna 41 of "Tx1" and the virtual antenna group SG3. As a result, by setting the antenna distance as shown in the upper diagram, it is possible to obtain performance equivalent to that achieved when radio waves from the transmitting antenna 41 of "Tx1" are received by "n × m" (here, 12) receiving antennas 42, as shown in the lower diagram. That is, with "n+m" antennas, it is possible to obtain performance equivalent to that of "1+n×m" antennas. Even in the arrangement shown in Fig. 6, the distance between the four receiving antennas 42 and the transmitting antenna 41 of "Tx1", the distance between the four receiving antennas 42 and the transmitting antenna 41 of "Tx2", and the distance between the four receiving antennas 42 and the transmitting antenna 41 of "Tx3" are different from one another. Therefore, it is possible to obtain performance equivalent to that obtained when "n×m" (here, 12) receiving antennas 42 are used for reception.

[0044] As shown in FIG. 8, in the first sensor 45A, the transmitting antenna 41 is provided with a radio wave absorbing wall 60 (restriction means) that absorbs radio waves. The radio wave absorbing wall 60 functions as a restriction member that restricts the emission range of radio waves. In this embodiment, the radio wave absorbing wall 60 has a first portion 62A corresponding to the transmitting antenna 41 of "Tx1," a second portion 62B corresponding to the transmitting antenna 41 of "Tx2," and a third portion 62C corresponding to the transmitting antenna 41 of "Tx3." Each of the portions 62A, 62B, and 62C of the radio wave absorbing wall 60 has an opening 61 through which radio waves from the antenna element 51 of the transmitting antenna 41 are emitted. The opening 61 of each of the portions 62A, 62B, and 62C collectively surrounds the multiple antenna elements 51 of each transmitting antenna 41 in a front view (the viewpoint shown in FIG. 6). Because the multiple antenna elements 51 are arranged in the vertical direction D3, the opening 61 has a shape having a longitudinal direction in the vertical direction D3.

[0045] As shown in FIG. 8 , each of the portions 62A, 62B, and 62C of the radio wave absorbing wall 60 has a side wall portion 64 protruding from the substrate 50 in the traveling direction D1 and an end wall portion 66 facing the substrate 50 and spaced apart from the substrate 50 in the traveling direction D1. A reference line SL2 perpendicular to the substrate 50 is set at the center of the antenna element 51 of the transmitting antenna 41. A pair of side wall portions 64 are provided on both sides of the reference line SL2 in the lateral direction D2. The end wall portions 66 are provided to extend in the lateral direction D2 from the tips of the pair of side wall portions 64. In this embodiment, the end wall portions 66 are inclined so as to move away from the antenna element 51 in the traveling direction D1 as they approach the reference line SL2 from the tips of the side wall portions 64. An opening 61 is formed in the end wall portion 66 near the reference line SL2. Radio waves W from the antenna element 51 are restricted by the end wall portions 66 at locations other than the opening 61 and are emitted to the outside only through the opening 61. The boundaries LM1 and LM2 of the radio wave emission range are defined by lines passing from the center of the antenna element 51 through both edges of the opening 61. The boundaries LM1 and LM2 are inclined with respect to the reference line SL2 so as to widen in the lateral direction D2 as they move away from the antenna element 51. In this embodiment, the side wall 64, the end wall 66, and the opening 61 have a symmetrical structure with respect to the reference line SL2. The material of the radio wave absorbing wall 60 is not particularly limited as long as it can absorb radio waves. For example, the radio wave absorbing wall 60 may be formed by attaching a radio wave absorbing sheet to the outside of a resin material. Additionally or alternatively, the radio wave absorbing wall 60 may have a shell structure and contain a liquid that absorbs radio waves. The liquid may be water or the like. The radio wave absorbing wall 60 may also have a solid structure.

[0046] As described above, the radio wave emission angle range of the transmitting antenna 41 can be limited to the range "θlimit=arcsin(λ / (2d))" where aliasing does not occur by the radio wave absorbing wall 60. Here, "d" is the inter-antenna distance of the receiving antennas 62 (see FIG. 6). By making the inter-antenna distance d greater than λ / 2, the first sensor 45A can have an angular resolution that exceeds the angular resolution θres=2 / N (N: number of antennas) when the inter-antenna distance d is λ / 2.

[0047] Returning to FIG. 5, the configuration of the detection device 40 will be described in more detail. The detection device 40 includes, from bottom to top, a first sensor 45A, a second sensor 45B, a third sensor 45C, and a fourth sensor 45D. The sensors 45A, 45B, 45C, and 45D are arranged so that their centers in the horizontal direction D2 coincide with one another. However, the centers do not have to coincide completely and may be offset in the horizontal direction D2. Alternatively, the first sensor 45A, the second sensor 45B, the third sensor 45C, and the fourth sensor 45D may be arranged from top to bottom. The substrates 50 of the sensors 45A, 45B, 45C, and 45D are separate from one another. However, a common substrate 50 may be used for all or part of the sensors 45A, 45B, 45C, and 45D.

[0048] The detection device 40 uses a sensor 45 with a wide detection angle at short distances, and a sensor with a narrow detection angle but better angular resolution than the short-distance sensor 45 at long distances (see FIG. 9). The angular resolution is adjusted by the distance between the virtual receiving antennas, and the sensor 45 with higher angular resolution at long distances has a longer inter-antenna distance. The detection angle of the (n+1)th sensor 45 is narrower than that of the nth sensor 45. Furthermore, the pitch of the transmitting antennas 41 in the (n+1)th sensor 45 is wider than that of the transmitting antennas 41 in the nth sensor 45. The pitch of the receiving antennas 42 in the (n+1)th sensor 45 is wider than that of the receiving antennas 42 in the nth sensor 45. Specifically, the detection angle of the second sensor 45B is narrower than that of the first sensor 45A. Furthermore, the pitch of the transmitting antennas 41 in the second sensor 45B is wider than that of the transmitting antennas 41 in the first sensor 45A. The pitch of the receiving antennas 42 in the second sensor 45B is wider than the pitch of the receiving antennas 42 in the first sensor 45A. The detection angle of the third sensor 45C is narrower than the detection angle of the second sensor 45B. Furthermore, the pitch of the transmitting antennas 41 in the third sensor 45C is wider than the pitch of the transmitting antennas 41 in the second sensor 45B. The pitch of the receiving antennas 42 in the third sensor 45C is wider than the pitch of the receiving antennas 42 in the second sensor 45B. The detection angle of the fourth sensor 45D is narrower than the detection angle of the third sensor 45C. Furthermore, the pitch of the transmitting antennas 41 in the fourth sensor 45D is wider than the pitch of the transmitting antennas 41 in the third sensor 45C. The pitch of the receiving antennas 42 in the fourth sensor 45D is wider than the pitch of the receiving antennas 42 in the third sensor 45C. The configurations of sensors 45B, 45C, and 45D are similar to that of the first sensor 45A described in Fig. 6, except that the pitch of the transmitting antennas 41 and the pitch of the receiving antennas 42 are different. Here, the pitch represents the distance between the antennas in the horizontal direction D2.

[0049] The angle resolution processor 46 acquires the detection results of the sensors 45A, 45B, 45C, and 45D and performs angle resolution processing. The angle resolution processor 46 selectively uses the sensors 45A, 45B, 45C, and 45D depending on the distance from the detection device 40. As shown in FIG. 9 , the angle resolution processor 46 defines a detection target area DE as a range of a predetermined distance and a predetermined width in front of the detection device 40. The angle resolution processor 46 also defines a non-detection target area NDE as a range of a predetermined distance and a predetermined width wider than the detection target area DE. Specifically, the detection target area DE is set to a range of 30 m from the detection device 40 and ±1 m in width. The non-detection target area NDE is an area outside the 30 m distance and ±1.3 m in width from the detection device 40. The angle resolution processor 46 determines "detection" when an object is detected within the detection target area DE, and determines "no detection" when an object is detected in the non-detection target area NDE or when no object is detected.

[0050] 9, the first sensor 45A has a detection target area AE1, the second sensor 45B has a detection target area AE2, the third sensor 45C has a detection target area AE3, and the fourth sensor 45D has a detection target area AE4.

[0051] As shown in FIG. 10, when the maximum horizontal detection angle of the first sensor 45A is less than ±90 degrees, a blind spot occurs in the detection target area AE1 in a range of at least (90 degrees - maximum detection angle) degrees to the left and right of the first sensor 45A (hatched area). The maximum detection angle θ of the first sensor 45A is set so that this blind spot falls within an acceptable range. If the allowable distance for the occurrence of a blind spot is 1.42 m, the relationship between the maximum detection angle θ and the allowable distance is "tan θ = 1 / 1.42", so the maximum detection angle θ of the first sensor 45A is 0.613 (rad) (35.1 degrees). The relationship between the antenna distance d (distance between the receiving antennas 42) and the maximum detection angle θmax is "θmax = sin -1 (λ / 2d)", so the antenna distance d when the maximum detection angle θmax is 35.1 degrees is d=λ / 2·sin(θmax)=λ / 1.15.

[0052] The relationship between the number of antennas, the antenna distance d, and the angular resolution θres of the first sensor 45A is θres = λ / Nd. If the number of virtual receiving antennas of the first sensor 45A (d = λ / 1.15) is 16, the angular resolution is θres = λ / (16 λ / 1.15) = 0.0719 (rad) = 4.12 degrees. As shown in Figure 9, with an angular resolution of 4.12 degrees, when distinguishing between an object 1 m away from the object 1.3 ...

[0053] The second sensor 45B needs to have a higher angular resolution than the first sensor 45A in order to identify objects beyond the 3.8 m detection distance of the first sensor 45A. Therefore, a second sensor 45B with approximately twice the angular resolution of the first sensor 45A is prepared. When the distance d between the antennas of the second sensor 45B is set to λ / 0.6, the angular resolution is θres = λ / (16 λ / 0.6) = 0.0375 (rad) = 2.15 degrees. With an angular resolution of 2.15 degrees, when distinguishing between an object 1 m away and an object 1.3 m away in the horizontal direction D2, the detection distance is limited to approximately 7.8 m.

[0054] The third sensor 45C needs to have a higher angular resolution than the second sensor 45B in order to identify objects beyond the 7.8 m detection distance of the second sensor 45B. Therefore, the third sensor 45C is prepared with an angular resolution approximately twice that of the second sensor 45B. When the distance d between the antennas of the third sensor 45C is set to λ / 0.3, the angular resolution is θres = λ / (16 λ / 0.3) = 0.0188 (rad) = 1.07 degrees. With an angular resolution of 1.07 degrees, when distinguishing between an object 1 m away and an object 1.3 m away in the horizontal direction D2, the detection distance is limited to approximately 15.9 m.

[0055] The fourth sensor 45D needs a higher angular resolution than the third sensor 45C in order to identify objects beyond the 15.9 m detection distance of the third sensor 45C. Therefore, a fourth sensor 45D with approximately twice the angular resolution of the third sensor 45C is prepared. When the distance d between the antennas of the fourth sensor 45D is set to λ / 0.15, the angular resolution is θres = λ / (16 λ / 0.15) = 0.0938 (rad) = 0.54 degrees. With an angular resolution of 0.54 degrees, it is possible to distinguish between an object at 1 m and an object at 1.3 m in the horizontal direction D2 up to a distance of approximately 31.7 m.

[0056] As shown in Figure 11, when trying to detect objects A and B that are at the same distance but at different angles and are located to the right of the sensor, the following will explain how to handle the angle FFT data from each sensor 45A, 45B, 45C, and 45D. Note that the angle θ A is 5 degrees, and the angle θ of object B B is set to 22 degrees. As a general method of angle FFT, the angle decomposition processing unit 46 first determines whether objects A and B are on the right or left side based on the polarity of the imaginary part of the angle FFT result for each of the sensors 45A, 45B, 45C, and 45D. In this example, objects A and B are only on the right side, so this signal processing method will be omitted.

[0057] Here, the angle resolving processor 46 identifies a virtual image from among the n+1 waveforms detected by the n+1 sensor 45 based on the n waveform detected by the n+1 sensor 45, and performs correction to delete the n+1 waveform identified as a virtual image. Specifically, when the detection device 40 measures objects A and B shown in FIG. 11, the angle resolving processor 46 obtains the results of the angle FFT of the first sensor 45A and the second sensor 45B, as shown in FIG. 12. In the first sensor 45A, within an angle range smaller than ±35.1 degrees, which corresponds to the Nyquist frequency, a waveform WA corresponding to object A is generated at a position of 5 degrees, and a waveform WB corresponding to object B is generated at a position of 22 degrees. In the first sensor 45A, the radio wave absorbing wall 60 limits the emission so that the angle is smaller than ±35.1 degrees, which corresponds to the Nyquist frequency. Therefore, aliasing does not occur.

[0058] Meanwhile, in the measurement results of the second sensor 45B, in an angle range smaller than ±17.5 degrees, which corresponds to the Nyquist frequency, a waveform WA corresponding to object A appears at a position of 5 degrees. In an angle range larger than ±17.5 degrees, which corresponds to the Nyquist frequency, aliasing occurs due to a waveform WB corresponding to object B at a position of 22 degrees. The signal processing target range PA of the second sensor 45B is the range of ±17.5 degrees, which is below the Nyquist frequency. Because the angle of object B is 22 degrees (17.5 + 4.5 degrees), a virtual image waveform FWB corresponding to object B appears at a position of -13 degrees (-17.5 + 4.5 degrees).

[0059] In response to this, the angle resolving processor 46 references the angle FFT of the measurement results of the first sensor 45A and determines that no object has been detected near the position of -13 degrees. Therefore, the angle resolving processor 46 determines that the waveform FWB near -13 degrees in the angle FFT of the measurement results of the second sensor 45B is a virtual image, deletes the data of the corresponding waveform FWB, and acquires the angle FFT related to the signal processing results of the second sensor 45B. The processed angle FFT shows only the waveform WA within the angle range of ±17.5 degrees. This allows the angle resolving processor 46 to detect object A using the second sensor 45B.

[0060] Furthermore, in the measurement results of the third sensor 45C, a waveform WA corresponding to object A is generated at a position of 5 degrees in an angle range smaller than ±8.75 degrees, which corresponds to the Nyquist frequency. Because the position of 22 degrees is restricted by the radio wave absorbing wall 60, a waveform WB corresponding to object B is not generated. The signal processing target range PA of the third sensor 45C is the range of ±8.75 degrees below the Nyquist frequency. Because the angle of object A is 5 degrees (8.75-3.75 degrees), a virtual image waveform FWA corresponding to object A is generated at a position of -12.5 degrees (-8.75-3.75 degrees).

[0061] In response, the angle resolving processor 46 references the angle FFT of the measurement results of the second sensor 45B and determines that no object has been detected near the -12.5 degree position. Therefore, the angle resolving processor 46 determines that the waveform FWA near -12.5 degrees in the angle FFT of the measurement results of the third sensor 45C is a virtual image, deletes the data of the corresponding waveform FWA, and acquires the angle FFT related to the signal processing results of the second sensor 45B. The processed angle FFT shows only the waveform WA within an angle range of ±8.75 degrees. This allows the angle resolving processor 46 to detect object A using the third sensor 45C. When obtaining the signal processing results of the fourth sensor 45D, the angle resolving processor 46 performs similar processing by reference to the angle FFT of the measurement results of the third sensor 45C.

[0062] Here, for each of the sensors 45B, 45C, and 45D except for the first sensor 45A on the short distance side, a physical emission restriction by the radio wave absorbing wall 60 is required in a range of at least twice the Nyquist frequency (see the range of RG in FIG. 12). In addition, as shown for the second sensor 45B in FIG. 12, the radio wave absorbing wall 60 may restrict the emission range so that it is not more than twice the Nyquist frequency in the angle FFT of the second sensor 45B, but is not less than the Nyquist frequency (see the range of RG in FIG. 12).

[0063] The nth sensor 45 may limit the output of its radio waves so that their reach is limited to the detection distance of the (n+1)th sensor. The detection distance is the distance from the detection device 40 to the front end of the detection target areas AE1, AE2, AE3, and AE4. The radio wave reach is the distance that the radio waves can reach from the nth sensor 45. The reach distance is longer than the detection distance. Specifically, the measurement results of the first sensor 45A are used to compare the detection results of the first sensor 45A in the detection target area AE1 (up to 3.8 m) with the measurement results of the second sensor 45B. Therefore, the radio waves of the first sensor 45A do not need to reach the detection distance of the detection target area AE3 of the third sensor 45C. Therefore, the first sensor 45A may limit the reach of its radio waves to the detection distance of the second sensor 45B. Similarly, the second sensor 45B may limit the reach of its radio waves to the detection distance of the third sensor 45C. The third sensor 45C may limit the reach of the radio wave to the detection distance of the fourth sensor 45D.

[0064] Next, the functions and effects of the RTG crane 10 and the detection device 40 according to this embodiment will be described.

[0065] First, a detection device according to a comparative example will be described. The detection device according to the comparative example uses a single sensor, with the antenna spacing set to λ / 2 so that it can receive reflected waves from a range of -90 degrees to +90 degrees. To achieve an angular resolution of 0.54 degrees (0.0094 rad) using a sensor with an antenna spacing of λ / 2, for example, 214 receiving antennas are required, since θres = 2 / n = 2 / n (θres: angular resolution, N: number of antennas). This results in a significant increase in the computational resources required for signal processing. Furthermore, in applications using millimeter-wave radar, even if the detection range for obstacles is a narrow angular range forward, radio waves are emitted over a wide range from -90 degrees to +90 degrees. Therefore, if an object with high reflectivity, such as a container, is located outside the detection range, it may be difficult to detect objects with low reflectivity within the detection range.

[0066] In contrast, in the detection device 40 according to this embodiment, the detection angle of the (n+1)th sensor 45 (first sensor) is narrower than the detection angle of the nth sensor (second sensor). Farther positions can be detected within a narrower angular range. Therefore, the angular range of the (n+1)th sensor 45 may be narrower than that of the nth sensor. Meanwhile, while lower angular resolution is acceptable for closer positions, higher angular resolution is required for farther positions. Meanwhile, the pitch of the transmitting antennas 41 in the (n+1)th sensor 45 is wider than that of the transmitting antennas 41 in the nth sensor. Furthermore, the pitch of the receiving antennas 42 in the (n+1)th sensor is wider than that of the receiving antennas 42 in the nth sensor. Because the pitch of the antennas in the (n+1)th sensor 45 is wider, higher angular resolution than the nth sensor can be achieved. Therefore, the detection device 40 can improve detection performance by obtaining high angular resolution at farther positions using the (n+1)th sensor 45, while performing detection with a low computational load due to the narrower angular range. The detection device 40 can perform detection with a low computational load by suppressing the angular resolution while ensuring a wide angular range for close positions using the nth sensor 45. As a result, the computational load can be reduced and the object detection performance can be improved.

[0067] The detection device 40 further includes an angle resolving processor 46 that acquires the detection results of the nth sensor 45 and the (n+1)th sensor 45 and performs angle resolving processing, and the angle resolving processor 46 may identify a virtual image generated by aliasing from the second waveform detected by the (n+1)th sensor 45 based on the first waveform detected by the nth sensor 45, and perform correction to delete the second waveform identified as the virtual image generated by aliasing. In this case, the angle resolving processor 46 can delete the waveform of the virtual image from the second waveform without performing complex calculations.

[0068] The transmitting antennas 41 of the nth sensor 45 and the (n+1)th sensor 45 may further include limiting means for limiting the emission range of the radio waves. In this case, the limiting means can easily adjust the radio wave emission angle of the transmitting antennas 41.

[0069] The limiting means may limit the emission range so that it is equal to or less than twice the Nyquist frequency and equal to or greater than the Nyquist frequency in the angle FFT of the (n+1)th sensor 45. In this case, by preventing radio waves from being transmitted over an unnecessarily wide range, it is possible to prevent unnecessary reflections from containers on both sides of the roadway, for example.

[0070] The nth sensor 45 may limit the output so that the reach of the radio waves is up to the detection distance of the (n+1)th sensor 45. In this way, by limiting the reach of the radio waves of the nth sensor 45 to a necessary distance, it is possible to suppress the occurrence of unnecessary reflections from containers on both sides of the travel path, etc.

[0071] The RTG crane 10 according to this embodiment is a mobile body that travels on a travelway and includes a detection device 40, and the detection device 40 has the above-described configuration. With this RTG crane 10, it is possible to obtain the same functions and effects as the above-described detection device 40.

[0072] The present invention is not limited to the above-described embodiments.

[0073] In the above-described embodiment, an RTG crane is used as an example of a mobile object, but the mobile object is not limited to this. For example, a crane other than an RTG crane may be used, such as a power shovel, a forklift, or a transport vehicle.

[0074] In the above-described embodiment, a radio wave absorbing wall is used as an example of a limiting member that limits the emission range of radio waves. However, the limiting member is not limited to this. For example, the limiting member may be a waveguide antenna (see, for example, FIG. 13) that limits the emission range of radio waves.

[0075] In the above-described embodiment, one sensor 45 is provided on one substrate 50. However, multiple sensors 45 may be provided on one substrate 50. For example, a third sensor 45C as shown in FIG. 13(a) is provided alone on the substrate 50. A fourth sensor 45D as shown in FIG. 13(b) is provided alone on the substrate 50. The circuit for the third sensor 45C and the circuit for the fourth sensor 45D are provided together on the substrate 50 shown in FIG. 13(c). On the substrate shown in FIG. 13(c), the antenna for the third sensor 45C and the antenna for the fourth sensor 45D are positioned offset from each other so as not to interfere with each other. While FIG. 13 illustrates an example in which the emission range is limited by a waveguide antenna, the sensors shown in FIG. 5 may be integrated on a single substrate 50. [Explanation of symbols]

[0076] 10...RTG crane (mobile body), 40...radar device, 41...transmitting antenna, 42...receiving antenna, 46...angle resolution processing unit, 60...radio wave absorbing wall (restriction means).

Claims

1. a first sensor and a second sensor for detecting a distance to an object using radio waves; the first sensor and the second sensor each have a plurality of transmitting antennas that transmit the radio waves and a plurality of receiving antennas that receive the reflected radio waves; a detection angle of the second sensor is narrower than a detection angle of the first sensor; a pitch of the transmitting antennas in the second sensor is wider than a pitch of the transmitting antennas in the first sensor; A detection device, wherein the pitch of the receiving antennas in the second sensor is wider than the pitch of the receiving antennas in the first sensor.

2. an angle resolution processing unit that acquires detection results of the first sensor and the second sensor and performs angle resolution processing; The angle resolution processing unit The detection device according to claim 1, wherein a virtual image is identified from among the second waveforms detected by the second sensor based on the first waveform detected by the first sensor, and correction is performed to delete the second waveform identified as the virtual image.

3. The detection device according to claim 1 , wherein the transmitting antennas of the first sensor and the second sensor further comprise limiting means for limiting the emission range of the radio waves.

4. 4. The detection device according to claim 3, wherein the limiting means limits the emission range so that the emission range is equal to or less than twice the Nyquist frequency in the angle FFT of the second sensor and equal to or greater than the Nyquist frequency.

5. The detection device according to claim 1 , wherein the first sensor limits the output of the radio wave so that the reachable distance of the radio wave is up to the detection distance of the second sensor.

6. A moving body that is equipped with a detection device and travels on a travel path, The detection device includes: a first sensor and a second sensor for detecting a distance to an object using radio waves; the first sensor and the second sensor each have a plurality of transmitting antennas that transmit radio waves and a plurality of receiving antennas that receive the reflected radio waves; a detection angle of the second sensor is narrower than a detection angle of the first sensor; a pitch of the transmitting antennas in the second sensor is wider than a pitch of the transmitting antennas in the first sensor; A moving body, wherein the pitch of the receiving antennas in the second sensor is wider than the pitch of the receiving antennas in the first sensor.

Images