RTG crane and radar device

Abstract

To provide an RTG crane that improves angular resolution of a radar device, while suppressing occurrence of aliasing, and to provide a radar device.SOLUTION: An RTG crane 10 comprises a radar device 40 for detecting a distance to an object using radio waves. The radar device 40 comprises: transmission antennas 41 for transmitting radio waves; and reception antennas 42 for receiving reflected radio waves. The size of an opening 61 of a first radio wave absorption wall 60 is set so that a radio wave emission range θ is θlimit or less of the formula (1). The θlimit is an angle of a limit at which aliasing does not occur. Accordingly, the first radio wave absorption wall 60 absorbs radio waves of a range where aliasing occurs, and is capable of emitting radio waves of a range where aliasing does not occur from the opening 61. Therefore, occurrence of aliasing can be suppressed, despite that a distance between the transmission antennas 41 is increased to improve angular resolution.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to an RTG crane and a radar device. [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 radar system that detects the distance and angle to an object in order to prevent the RTG crane from coming into contact with the object, for example, if the object is present in the travel path. The radar system's angular resolution can be improved by narrowing the spacing between multiple receiving antennas that are spaced apart. However, increasing the distance between the receiving antennas can result in aliasing in the results of frequency analysis used to calculate the angle.

[0005] An object of the present disclosure is to provide an RTG crane and a radar device that can improve the angular resolution of the radar device while suppressing the occurrence of the above-mentioned aliasing. [Means for solving the problem]

[0006] An RTG crane according to one aspect of the present disclosure is an RTG crane that travels on a travelway and is equipped with a MIMO radar device that detects the distance and angle to an object using radio waves, the radar device having a transmitting antenna that transmits radio waves and a receiving antenna that receives the reflected radio waves, the multiple receiving antennas being arranged at a distance d from each other, the multiple transmitting antennas being arranged at a distance equal to the distance d multiplied by the number of receiving antennas, at least the transmitting antennas being provided with a limiting member that limits the radiation range of the radio waves, the limiting member being such that the radio wave radiation range θ is within the θ limit It is set as follows:

[0007]

number

[0008] This RTG crane is equipped with a MIMO radar device that uses radio waves to detect the distance to an object. This radar device has a transmitting antenna that transmits radio waves and a receiving antenna that receives the reflected radio waves. In contrast, the limiting member has a radio wave emission range θ that is within the θ limit It is set as follows: θ shown in Equation (1) limit is the limit angle at which aliasing does not occur. Therefore, the limiting member limits radio waves within the range where aliasing occurs, and allows radio waves within the range where aliasing does not occur to be emitted. Therefore, even if the distance between the transmitting antennas is increased to improve the angular resolution, the occurrence of aliasing can be suppressed. As described above, the angular resolution of the radar device can be improved while suppressing the occurrence of aliasing.

[0009] The limiting member may be a first radio wave absorbing wall that absorbs radio waves and / or a waveguide antenna. By adjusting the size of the opening of the first radio wave absorbing wall and / or the waveguide antenna, it is possible to adjust the radio wave emission range θ.

[0010] A plurality of receiving antennas are arranged at a distance from each other, and a second radio wave absorbing wall that absorbs radio waves is provided on the receiving antennas. The size of the opening of the second radio wave absorbing wall is set such that the radio wave incidence range θ is θ limit In this case, it is possible to improve the angular resolution of the radar device while suppressing the occurrence of aliasing on the receiving antenna side as well.

[0011] Each transmitting antenna may have a plurality of antenna elements arranged in a direction perpendicular to the direction in which the plurality of transmitting antennas are arranged, and the opening of the restricting member may surround the plurality of antenna elements collectively in a front view, in which case the radiation pattern of the transmitted radio wave can be changed.

[0012] A radar device according to one aspect of the present disclosure is a MIMO radar device that detects a distance to an object using radio waves, and includes a transmitting antenna that transmits radio waves and a receiving antenna that receives reflected radio waves, wherein the multiple receiving antennas are arranged at a distance d from each other, and the multiple transmitting antennas are arranged at a distance equal to the distance d multiplied by the number of receiving antennas, and at least the transmitting antenna is provided with a limiting member that limits the radio wave emission range, and the limiting member limits the radio wave emission range θ to a value smaller than θ in Equation (1). limit It is set as follows:

[0013]

number

[0014] This radar device can provide the same functions and effects as the RTG crane described above. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to improve the angular resolution of a radar device while suppressing the occurrence of aliasing. [Brief explanation of the drawings]

[0016] [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 radar device according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram for explaining the relationship between the distances of a transmitting antenna and a receiving antenna. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII shown in FIG. 5. [Figure 8] 10 is a graph showing angle data after angular FFT calculation of a signal detected by a receiving antenna. [Figure 9] FIG. 1 is a schematic plan view showing an example of use of a radar device. [Figure 10] FIG. 1 is a schematic plan view showing an example of use of a radar device. [Figure 11] FIG. 10 is a cross-sectional view showing a radar device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] 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 that are placed in the container yard 2 and that load and unload the containers C, and a remote control room 5 that can remotely control the plurality of RTG cranes 10.

[0019] 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.

[0020] 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.

[0021] 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 placed. For example, an RTG crane 10 is placed for each lane L. The number of RTG cranes 10 placed in a lane L may be one or more.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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."

[0032] 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.

[0033] 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 can be detected where the running sections 15A, 15B are expected to pass.

[0034] 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.

[0035] Each of the detection units 30A, 30B, 30C, and 30D has a radar device 40. The number of radar devices 40 included in each of the detection units 30A, 30B, 30C, and 30D is not particularly limited. However, the radar 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 radar device 40.

[0036] Next, the configuration of a radar device 40 that can improve angular resolution will be described with reference to Fig. 5. Fig. 5 is a diagram showing the radar device 40 according to this embodiment. As shown in Fig. 5, the radar device 40 is configured by providing elements and wiring on a substrate 50. Fig. 5 is a diagram showing the radar device 40 as viewed from outside the traveling section 15 in the traveling direction D1. The radar device 40 according to this embodiment employs MIMO (Multiple Input Multiple Output), which uses multiple antennas on the transmitting and receiving sides.

[0037] The radar device 40 includes multiple transmitting antennas 41 and multiple receiving antennas 42. The multiple transmitting antennas 41 are antennas that transmit radio waves (millimeter waves) forward. The multiple receiving antennas 42 are antennas that receive radio waves reflected by objects. For the purpose of explanation, the radar device 40 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 radar device 40 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."

[0038] The radar device 40 is a continuous frequency modulation type radar device 40. The continuous frequency modulation type radar device 40 is a type of radar that transmits radio waves, i.e., chirps, that are modulated so that the frequency of the transmission waves from the transmitting antenna 41 changes continuously over time. The radar device 40 generates an intermediate frequency signal (IF signal) based on the frequency difference between the transmission 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.

[0039] 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.

[0040] The radar device 40 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 have antenna elements 51 configured with flat plate-shaped patterns. In the example shown in FIG. 6 , the transmitting antenna 41 and receiving antenna 42 have multiple (four) 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. However, the transmitting antenna 41 and receiving antenna 42 are not limited to microstrip antennas, and other types of antennas may be used.

[0041] Here, the distance between the antennas will be described. 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 closest to the transmitting antenna 41, namely "Rx1," "Rx2," "Rx3," and "Rx4." The central transmitting antenna 41 is disposed at a distance S1 from the receiving antenna 42 "Rx1" in the horizontal direction D2. 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 antennas 41 are arranged in order from closest to the receiving antenna 42, namely "Tx1," "Tx2," and "Tx3."

[0042] Next, the relationship between the distances of the transmitting antennas 41 and the receiving antennas 42 will be described with reference to FIG. 6. The upper part of FIG. 6 shows an actual antenna arrangement. However, the radio wave absorbing wall is omitted from the upper diagram. The lower part of FIG. 6 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 wave. Therefore, the combinations "Tx1 → Rx2," "Tx1 → Rx3," and "Tx1 → Rx4" exist.

[0043] 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.

[0044] 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. In other words, with "n+m" antennas, it is possible to obtain the same performance as with "1+n×m" antennas.

[0045] Next, aliasing will be explained. As shown in Fig. 7, if the distance between the receiving antennas 42 is "d," the arrival angle of the radio wave W is "Θ," and the wavelength of the radio wave W is "λ," the phase difference Φ (rad) between the antennas is expressed by equation (2). Note that a reference line SL1 perpendicular to the substrate 50 is set at the center position of the antenna element 51 of the receiving antenna 42. The arrival angle Θ is the angle between the radio wave W and the reference line SL1 when viewed from the up-down direction D3.

[0046]

number

[0047] FIG. 8 is a graph showing angle data after angular FFT calculation of the signal detected by the receiving antenna 42. The horizontal axis represents the angle of the target, and the vertical axis represents frequency. The center of the angle is 0°, with one angle direction (to the right) representing a positive angle and the other angle direction (to the left) representing a negative angle. Regions E1 and E2 between the peak on the positive side and the peak on the negative side of the angle center are regions where aliasing does not occur. Region E3, where the angle is larger to the right than E1, is the aliasing region of E1, and region E4, where the angle is larger to the left than E2, is the aliasing region of E2. In aliasing regions E3 and E4, the influence of radio waves other than those of the target appears, making accurate angle detection difficult. Conventionally, radar devices have been used with a distance d between antennas of "d = λ / 2" to prevent aliasing.

[0048] Here, equation (2) can be transformed to equation (3). As mentioned above, aliasing occurs when the phase difference φ exceeds the range of π, so by substituting "φ = π" into equation (3), the limit angle at which aliasing does not occur can be found. Specifically, the limit angle θ at which aliasing does not occur is limit is expressed by the formula (1). At least one of the radio wave emission range of the transmitting antenna 41 and the radio wave incidence range of the receiving antenna 42 is defined by a limit angle θ limit If the distance d between the antennas can be limited to the following, aliasing will not occur even if d > λ / 2. In this embodiment, the radar device 40 is equipped with a radio wave absorbing wall 60 that limits the radio wave emission range of the transmitting antenna 41, thereby adopting a structure that can suppress the occurrence of aliasing (see Figures 5 and 7). The angular resolution is expressed as "(θres) = Nλ / d (N is the number of antennas)". Therefore, the greater the distance d between the antennas, the more improved the angular resolution can be. In this embodiment, since it is possible to calculate the angle without aliasing even if "d > λ / 2", it is possible to improve the angular resolution compared to conventional radar devices with "d = λ / 2".

[0049]

number

[0050] As shown in FIG. 5, in the radar device 40, a first radio wave absorbing wall 60 that absorbs radio waves is provided on the transmitting antenna 41. The first radio wave absorbing wall 60 functions as a limiting member that limits the emission range of radio waves. In this embodiment, the first 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 63C corresponding to the transmitting antenna 41 of “Tx3.” Each of the portions 62A, 62B, and 62C of the first 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. 5). Because the multiple antenna elements 51 are arranged in the vertical direction D3, the opening 61 has a shape whose longitudinal direction is in the vertical direction D3.

[0051] As shown in FIG. 7 , each of the portions 62A, 62B, and 62C of the first radio wave absorbing wall 60 has a side wall portion 64 that protrudes from the substrate 50 in the traveling direction D1, and an end wall portion 66 that faces the substrate 50 and is spaced from the substrate 50 in the traveling direction D1. A reference line SL2 that is perpendicular to the substrate 50 is set at the center position of the antenna element 51 of the transmitting antenna 41. A pair of side wall portions 64 is provided on both sides of the reference line SL2 in the lateral direction D2. The end wall portions 66 are provided so as to extend in the lateral direction D2 from the tip ends 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 tip ends of the side wall portions 64. An opening 61 is formed in the end wall portion 66 near the reference line SL2. The size of the opening 61 is determined by the radio wave emission range θ being the θ in the above-mentioned formula (1). limitThe radio waves W from the antenna element 51 are restricted by the end wall 66 at locations other than the opening 61 and are emitted to the outside only through the opening 61. Boundaries LM1 and LM2 of the radio wave emission range θ 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 that they widen in the lateral direction D2 as they move away from the antenna element 51. The angle between the boundaries LM1 and LM2 defines the radio wave emission range θ. 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 first radio wave absorbing wall 60 is not particularly limited as long as it can absorb radio waves. For example, the first 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 first 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 first radio wave absorbing wall 60 may also have a solid structure.

[0052] The detection of an object using the radar device 40 according to this embodiment will be described with reference to FIG. 9. In the example shown in FIG. 9, the detection target area DE for an obstacle of the RTG crane 10 ranges from the travel section 15 forward in the travel direction D1 and 2.5 m in the lateral direction D2. For example, when the radar device 40 detects an obstacle in a target area DTE within the detection target area DE, the radar device 40 needs to know the exact angle of the object to determine whether the detected object is inside or outside the target area DTE. When the distance D from the radar device 40 to the target area DTE is 0 m, the required detection angle range is -90 to 90 degrees, and therefore the distance d between the antennas must be set to λ / 2. However, when the distance D is greater than 0 m, the required detection angle range is less than -90 to 90 degrees, and the distance d between the antennas can be set to a larger value. In this case, when the radar device 40 according to this embodiment is used, the limit angle θ at which aliasing occurs is determined. limitThe first radio wave absorbing wall 60 is provided so that the radio wave emission range falls within the range shown below. In FIG. 9, the radio wave emission range when the first radio wave absorbing wall 60 is not used is indicated by "AR1." Furthermore, the radio wave emission range when the emission range is limited by the first radio wave absorbing wall 60 is indicated by "AR2." Even with the range limited, the radio wave emission range AR2 can still cover the target area DTE. By limiting the radio wave emission range and increasing the distance d between the antennas in this way, the angular resolution within the detection range can be improved. Note that, as shown in FIG. 10, the distance D of the target area DTE may be set larger than that shown in FIG. 9 and near the edge of the detection target area DE. In this case, the radar device 40 may further narrow the radio wave emission range AR2 using the first radio wave absorbing wall 60.

[0053] Next, the functions and effects of the RTG crane 10 and the radar device 40 according to this embodiment will be described.

[0054] The RTG crane 10 according to this embodiment is equipped with a MIMO radar device 40 that detects the distance to an object using radio waves. The radar device 40 includes a transmitting antenna 41 that transmits radio waves and a receiving antenna 42 that receives the reflected radio waves. In contrast, the size of the opening 61 in the first radio wave absorbing wall 60 is determined by the radio wave emission range θ being θ limit It is set as follows: θ shown in Equation (1) limit is the limit angle at which aliasing does not occur. Therefore, the first radio wave absorbing wall 61 absorbs radio waves within the range where aliasing occurs, and allows radio waves within the range where aliasing does not occur to exit from the opening 61. Therefore, even if the distance between the transmitting antennas 41 is increased in order to improve the angular resolution, aliasing does not occur. As described above, the angular resolution of the radar device 40 can be improved without causing aliasing.

[0055] The limiting member may be a first radio wave absorbing wall 60 that absorbs radio waves. By adjusting the size of the opening 61 of the first radio wave absorbing wall 60, it is possible to adjust the radio wave emission range θ.

[0056] Each transmitting antenna 41 has a plurality of antenna elements 51 arranged in a direction (vertical direction D3) perpendicular to the direction (horizontal direction D2) in which the plurality of transmitting antennas 41 are arranged, and the opening 61 of the first radio wave absorbing wall 60 may surround all of the antenna elements 51 in a front view. In this case, the radiation pattern of the transmitted radio waves can be changed.

[0057] The radar device 40 according to this embodiment is a radar device 40 that detects the distance to an object using radio waves, and includes a transmitting antenna 41 that transmits radio waves and a receiving antenna 42 that receives reflected radio waves. The multiple receiving antennas are arranged at a distance d from each other, and the multiple transmitting antennas are arranged at a distance obtained by multiplying the distance d by the number of receiving antennas 42. At least the transmitting antenna 41 is provided with a first radio wave absorbing wall 60 that absorbs radio waves. The size of the opening 61 of the first radio wave absorbing wall 60 is determined by the radio wave emission range θ being θ in Equation (1). _limit It is set as follows:

[0058]

number

[0059] According to this radar device 40, it is possible to obtain the same functions and effects as those of the RTG crane 10 described above.

[0060] The present invention is not limited to the above-described embodiments.

[0061] For example, in the above-described embodiment, no radio wave absorbing wall was provided on the side of the receiving antenna 42. However, if sufficient space can be secured between the receiving antennas 42 by further increasing the distance d between the antennas, a second radio wave absorbing wall 70 as shown in Fig. 11 may be provided. That is, multiple receiving antennas 42 are arranged apart from each other, and the second radio wave absorbing wall 70 that absorbs radio waves is provided on the receiving antennas 42, and the size of the opening 71 of the second radio wave absorbing wall 70 is set so that the radio wave incidence range θ is θlimit In this case, the angular resolution of the radar device 40 can be improved while suppressing the occurrence of aliasing on the receiving antenna 42 side as well.

[0062] In the above-described embodiment, an RTG crane is used as an example, but the present invention is not limited to this. For example, a crane other than an RTG crane may be used, such as a power shovel or a forklift.

[0063] 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 that limits the emission range of radio waves. [Explanation of symbols]

[0064] 10...RTG crane, 40...radar device, 41...transmitting antenna, 42...receiving antenna, 51...antenna element, 60...first radio wave absorbing wall (restricting member), 70...second radio wave absorbing wall.

Claims

1. An RTG crane that travels on a travel path and is equipped with a MIMO radar device that detects the distance to an object using radio waves, The radar device is a plurality of transmitting antennas for transmitting the radio waves; a plurality of receiving antennas for receiving the reflected radio waves; The plurality of receiving antennas are arranged at a distance d from each other, the plurality of transmitting antennas are arranged at intervals of a distance equal to the distance d multiplied by the number of receiving antennas; At least the transmitting antenna is provided with a limiting member that limits the emission range of radio waves, The limiting member has a radio wave emission range θ of θ in formula (1). ｌｉｍｉｔ An RTG crane configured to: [Equation 1] where λ is the wavelength of the radio wave.

2. The RTG crane according to claim 1 , wherein the restricting member is a first radio wave absorbing wall and / or a waveguide antenna that absorbs the radio waves.

3. The plurality of receiving antennas are arranged at intervals from each other, the receiving antenna is provided with a second radio wave absorbing wall that absorbs radio waves; The size of the opening of the second radio wave absorbing wall is such that the radio wave incidence range θ is ｌｉｍｉｔ The RTG crane according to claim 1, wherein the RTG crane is set to:

4. Each of the transmitting antennas has a plurality of antenna elements arranged in a direction perpendicular to a direction in which the plurality of transmitting antennas are arranged, The RTG crane according to claim 1 , wherein the opening of the restricting member collectively surrounds the plurality of antenna elements in a front view.

5. A MIMO radar device that detects the distance to an object using radio waves, a transmitting antenna for transmitting the radio waves; a receiving antenna for receiving the reflected radio waves, The plurality of receiving antennas are arranged at a distance d from each other, the plurality of transmitting antennas are arranged at intervals of a distance equal to the distance d multiplied by the number of receiving antennas; At least the transmitting antenna is provided with a limiting member that limits the emission range of radio waves, The limiting member has a radio wave emission range θ of θ in formula (1). ｌｉｍｉｔ 1. A radar device configured to: [Equation 2] where λ is the wavelength of the radio wave.

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