Link mechanism control device

Abstract

To provide a link mechanism which allows radio waves for controlling to be received using antennas provided in links, without degrading the strength of housings of the links.SOLUTION: A link mechanism 1 comprises: a plurality of links 11-14 coupled by joints driven by driving means; and link-side antennas 21-23 provided in the links 11-13. The links 11-13 in which the link-side antennas 21-23 are provided include housings 31-33 of a frequency selection board which transmits a frequency band used in radio communication using the link side antennas 21-23, and the link side antennas 21-23 are arranged respectively inside the housings 31-33.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a linkage having one or more link-side antennas for wireless communication. [Background technology]

[0002] In link mechanisms of robot arms and the like, it is desirable to make the wiring wireless in order to prevent accidents such as wire breakage. For this reason, for example, wireless communication is performed between the link and a base to which the base end of the link mechanism is connected, thereby reducing the amount of wiring within the link mechanism (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-151675 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when receiving a control signal with an antenna disposed in the link and controlling a joint or the like based on the received control signal, in order for the antenna disposed in the link to be able to receive radio waves, it was necessary to drill a hole in the metal housing of the link at the location of the antenna or to use a resin housing. Whether drilling a hole in the location of the antenna or using a resin housing, there were problems in that the strength of the link was reduced and noise also reached the antenna.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a link mechanism that can selectively receive control radio waves using an antenna provided in the link without reducing the strength of the link's housing. [Means for solving the problem]

[0006] In order to achieve the above object, a link mechanism according to one aspect of the present invention comprises a plurality of links connected by joints driven by a driving means, and one or more link-side antennas provided on at least one of the plurality of links, and among the plurality of links, a link provided with a link-side antenna has a housing of a frequency selective plate that transmits the frequency band used in wireless communication using the link-side antenna, and the link-side antenna is arranged within the housing.

[0007] This configuration improves the strength of the housing of the link where the link-side antenna is installed, because frequency selective surfaces usually have a metal plate. Also, since only radio waves in the desired frequency band can be transmitted through the frequency selective surface, noise at frequencies other than the desired frequency band can be reduced.

[0008] In the link mechanism according to an aspect of the present invention, the plurality of resonant elements may be periodically arranged in four-fold or six-fold symmetry on the frequency selective surface.

[0009] This configuration allows signals of a wider variety of polarizations to pass through the frequency selective surface, and the link-side antenna can properly receive the desired signal even if the angle of the joint changes. [Effects of the Invention]

[0010] According to the link mechanism according to one aspect of the present invention, it is possible to improve the strength of the housing of the link on which the link-side antenna is provided, and also to reduce noise. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a link mechanism control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram illustrating a frequency selective surface according to the embodiment; [Figure 3A]FIG. 2 is a plan view showing a frequency selective surface in the embodiment; [Figure 3B] FIG. 2 is a plan view showing a metal plate in the frequency selective surface according to the embodiment; [Figure 4] FIG. 3 is a cross-sectional view of a frequency selective surface according to the embodiment; [Figure 5A] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5B] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5C] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5D] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5E] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5F] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5G] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5H] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5I] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5J] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 5K] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 6A] FIG. 2 is a plan view showing a frequency selective surface in the embodiment; [Figure 6B] FIG. 2 is a plan view showing a metal plate in the frequency selective surface according to the embodiment; [Figure 7] FIG. 3 is a cross-sectional view of a frequency selective surface according to the embodiment; [Figure 8A] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8B] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8C] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8D] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8E] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8F] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8G] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8H] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8I] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; [Figure 8J] FIG. 10 is a diagram showing frequency characteristics of S parameters of a frequency selective surface according to the embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0012] A link mechanism control device and a link mechanism according to the present invention will be described below using embodiments. In the following embodiments, components with the same reference numerals are the same or equivalent, and repeated description may be omitted. In the link mechanism according to this embodiment, a link provided with a link-side antenna for transmitting and receiving radio waves to and from a base-end-side antenna has a housing of a frequency selective plate that transmits the frequency band used in wireless communication between the two antennas, and the link-side antenna is disposed within the housing.

[0013] FIG. 1 is a schematic diagram showing the configuration of a link mechanism control device 100 according to this embodiment. The link mechanism control device 100 according to this embodiment includes a link mechanism 1, a base-side antenna 3, an access point 4, and a control unit 5. The link mechanism 1 includes a plurality of links 11 to 14 connected by joints 41 to 43 driven by a driving means, and link-side antennas 21 to 23 disposed within the links 11 to 13, respectively. Of the plurality of links 11 to 14, the base-side link 11 may be fixed to a base 2, or may be connected to the base 2 so as to be rotatable. Furthermore, links 11 and 12, links 12 and 13, and links 13 and 14 are rotatably connected by joints 41 to 43, respectively.

[0014] Although the present embodiment will be described primarily with reference to a case where the link mechanism 1 has four links 11 to 14, the number of links included in the link mechanism 1 is not limited. For example, the link mechanism 1 may have two, three, or five or more links. The multiple links are typically connected in series. Furthermore, in the present embodiment, the hand (end effector) at the most distal end of the link mechanism 1 is also considered to be a single link. Power may be supplied to each of the links 12 to 14, for example, using wiring or by wireless power supply at the joints. In the latter case, wireless power supply at the joints, as described in Patent Document 1, may be used. From the perspective of reducing the amount of wiring, it is preferable to supply power to each of the links 12 to 14 by wireless power supply at the joints. Wireless power supply at a certain joint may be performed, for example, using a power transmitting coil for contactless power transmission provided on the first link side of the joint and a power receiving coil for contactless power transmission provided on the second link side of the joint. The first and second links are connected at their joints, with the first link at the base end and the second link at the tip end. The power receiving coil receives power transmitted contactlessly from the power transmitting coil. For example, when link 11 is fixed to base 2, power may be supplied to link 11 using a wire, and when link 11 is connected to base 2 so as to be rotatable, power may be supplied wirelessly.

[0015] In this embodiment, the case where link-side antennas 21 to 23 are provided on links 11 to 13, respectively, is described, but this is not necessarily the case. For example, if link 11 is fixed to base 2, link 11 may not be provided with link-side antenna 21. Furthermore, if link 14 is also controlled based on a control signal, link 14 may also be provided with a link-side antenna. Furthermore, for example, links that do not require the transmission and reception of control signals or links that are provided with wiring through joints may not be provided with link-side antennas. Furthermore, for example, there may be links that only have a rotation transmission mechanism that rotates a distal joint in response to the rotation of a proximal joint. In this case, the link that only has the rotation transmission mechanism does not need to transmit and receive signals and therefore may not be provided with a link-side antenna. Note that the rotation transmission mechanism may be configured, for example, with a pulley and a belt, or gears. Thus, link mechanism 1 may have, for example, one link-side antenna, or two or more link-side antennas. When the link mechanism 1 has two or more link-side antennas, it is usually preferable that the two or more link-side antennas are provided on different links.

[0016] The links 11 to 14 have housings 31 to 34, respectively. Of the multiple links 11 to 14, the links 11 to 13 provided with link-side antennas 21 to 23 have housings 31 to 33 that are frequency selective surfaces (FSSs) that transmit the frequency bands used in wireless communication using the link-side antennas 21 to 23. In each of the links 11 to 13, the link-side antennas 21 to 23 are disposed within the housings 31 to 33. The housings 31 to 33 may be formed by attaching a frequency selective surface to a frame made of metal or carbon fiber, or by deforming the frequency selective surface to the shape of the housing. When links 11 to 13 have frequency selective board housings 31 to 33, it may mean, for example, that the entire housings 31 to 33 are made up of frequency selective boards, or that at least the parts of housings 31 to 33 through which radio waves used in wireless communication between the base end antenna 3 and link side antennas 21 to 23 pass are made up of frequency selective boards.

[0017] As shown in FIG. 2, the frequency selective plate 8 is a plate-like member that transmits a certain frequency f1 but does not transmit another frequency f2. For example, when a 60 GHz band signal is transmitted and received in wireless communication between the base-end antenna 3 and the link-side antennas 21 to 23, the frequency selective plate 8 may function as a bandpass filter that transmits the 60 GHz band signal and attenuates signals of other frequencies. Since the frequency selective plate 8 of this embodiment passes only wireless signals of a specific frequency band, it is typically a hole-type frequency selective plate in which multiple resonant elements are periodically arranged. The multiple resonant elements may or may not have the same shape. In the latter case, for example, adjacent resonant elements may have different hole sizes. Even in this case, it is preferable that multiple resonant elements of the same shape are periodically arranged. Specific examples of the frequency selective plate 8 will be described later.

[0018] The housing 34 of the link 14 that does not have the link-side antennas 21 to 23 disposed therein may be made of, for example, a frequency selective surface, or any other material. In the latter case, from the viewpoint of improving strength, the housing 34 may be made of, for example, metal.

[0019] In this embodiment, the link mechanism 1 is mainly described as a robot arm, but the link mechanism 1 may be something other than a robot arm. Examples of link mechanisms 1 other than a robot arm include the legs of a quadruped robot, the arms and legs of a humanoid robot, and the link mechanisms of a crane, etc.

[0020] Each of the links 11-14 may have, for example, a driving means for driving a joint on the base end side or the tip end side, a sensor such as a rotary encoder for acquiring the displacement of the rotation axis of the driving means, a control circuit for controlling the driving of the driving means based on a control signal, and a communication means for communicating with the control unit 5 via the link-side antennas 21-23. The driving means, sensor, control circuit, communication means, etc. may be provided in, for example, the link provided with the link-side antenna. Note that the configuration of the link mechanism 1 other than the transmission and reception of control signals, etc. is similar to that of a link mechanism of a conventional robot arm, etc., and a detailed description thereof will be omitted.

[0021] The base-end antenna 3 is provided at a position on the base end side of the link mechanism 1 so as to be able to communicate wirelessly with each of the link-side antennas 21 to 23 when each of the joints 41 to 43 of the link mechanism 1 is at any angle. Note that while FIG. 1 shows the case where the base-end antenna 3 is provided on the base 2, this is not essential. The base-end antenna 3 may also be provided at a position on the base end side of the link mechanism 1 other than the base 2. However, it is preferable that the base-end antenna 3 is provided around the base end of the link mechanism 1. The number of base-end antennas 3 is not important. For example, there may be one base-end antenna 3, or two or more base-end antennas 3.

[0022] The access point 4 wirelessly transmits a control signal from the base-side antenna 3 to each of the plurality of link-side antennas 21-23. The access point 4 may also receive, via the base-side antenna 3, signals wirelessly transmitted from the plurality of link-side antennas 21-23 to the base-side antenna 3. The access point 4 may be considered to correspond to, for example, a base station of a wireless LAN. Therefore, the access point 4 may perform wireless communication with communication means provided in the links 11-13.

[0023] The wavelength of the radio waves used in the wireless communication between the base-end antenna 3 and the link-side antennas 21-23 is not particularly limited, but may be, for example, 10 mm or less. That is, control signals may be transmitted from the base-end antenna 3 to the link-side antennas 21-23 using radio waves with a wavelength of, for example, 10 mm or less, and signals transmitted from the links 11-13 may be transmitted from the link-side antennas 21-23 to the base-end antenna 3 using radio waves with a wavelength of, for example, 10 mm or less. The radio waves may be, for example, millimeter waves, submillimeter waves, terahertz waves, or other radio waves with a wavelength of 10 mm or less. In this embodiment, a case where control signals and the like are transmitted using millimeter waves will be mainly described.

[0024] In wireless communications using long-wavelength radio waves, such as 2.45 GHz or 5 GHz used in wireless LANs, it is difficult to secure a wide frequency band. Link mechanism 1 typically includes multiple drive mechanisms and multiple sensors, each of which must communicate with one another, requiring a wide frequency band. To achieve this, wireless communications using shorter-wavelength waves, such as millimeter waves, submillimeter waves, or terahertz waves, are preferable.

[0025] On the other hand, in wireless communication using short-wavelength radio waves such as millimeter waves, if line of sight between the transmitting and receiving antennas cannot be ensured, the transmitted radio waves may be significantly attenuated, and communication may not be established. Therefore, when wireless communication using millimeter waves or the like is performed, it is preferable that the base-side antenna 3 and the link-side antennas 21 to 23 are arranged so that line-of-sight communication is achieved when the frequency selective plate 8 is ignored, that is, so that communication can be performed with no obstacles between the two antennas.

[0026] The control unit 5 controls the transmission of control signals by the access point 4. The control unit 5 may cause the access point 4 to transmit control signals corresponding to each of the links 11 to 13. The control unit 5 drives each of the joints 41 to 43 in the link mechanism 1 based on the control signals. Therefore, the control unit 5 controls the operation of the link mechanism 1 using the control signals. Note that the control unit 5 may control the transmission by feedback control using sensing results (e.g., displacement of the rotation axis) transmitted by a sensor transmitted from the link mechanism 1. In this case, the control unit 5 may receive the sensing results transmitted from each of the links 11 to 13 via the access point 4 and use the results to transmit control signals via the access point 4. Note that the control by the control unit 5 is the same as that of a conventional link mechanism, except that the transmission path of the control signal has changed from wired to wireless, and therefore a detailed description thereof will be omitted.

[0027] The link-side antennas 21-23 are connected to communication means provided in the links 11-13, respectively. Signals received by the link-side antennas 21-23 are passed to the communication means and used to control, for example, the actuation of the joints 41-43 in each of the links 11-13. The control circuits in each of the links 11-13 may wirelessly transmit sensing results acquired by sensors to the base-side antenna 3 via the communication means and the link-side antennas 21-23. Signals transmitted from each of the links 11-13 are transmitted via the communication means and each of the link-side antennas 21-23 and received by the base-side antenna 3. The signals received by the base-side antenna 3 are passed to the control unit 5 via the access point 4, and control, etc., is performed in accordance with the signals. In this embodiment, a case will be mainly described in which signals are transmitted from the base-side antenna 3 to the link-side antennas 21-23 and in the opposite direction, respectively, but this is not essential. It is also possible to only transmit signals from the base-end antenna 3 to the link-side antennas 21 to 23. In this case, for example, instructions regarding the displacement of the rotation axis of each of the joints 41 to 43 may be transmitted from the base-end antenna 3 to each of the link-side antennas 21 to 23, and feedback control regarding the drive means may be performed in each of the links 11 to 13 in accordance with the instructions.

[0028] Next, specific examples of frequency selective surfaces will be described. Here, a frequency selective surface with four-fold symmetry and a frequency selective surface with two-fold symmetry will be described.

[0029] [Four-fold symmetric frequency selective surface] FIG. 3A is a diagram showing an example of a frequency selective plate 8 in which a plurality of resonant elements, each having a hole of the same shape, are periodically arranged. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3A. As shown in FIG. 4, the frequency selective plate 8 may include a metal plate 51 having a plurality of periodically arranged holes 51a, a pair of dielectric plates 52 and 53 respectively arranged on both sides of the metal plate 51, and a pair of metal foils 54 and 55 respectively provided on the outer surfaces of the pair of dielectric plates 52 and 53, i.e., on the side opposite the metal plate 51, and having holes 54a and 55a at positions corresponding to the holes 51a. In the frequency selective plate 8, each resonant element is composed of a hole 51a and a metal foil 54 or 55 having a hole 54a or 55a, which is arranged at the opening of the hole 51a via the dielectric plates 52 and 53, respectively.

[0030] 3B is a plan view showing the metal plate 51. As shown in FIGS. 3B and 4, each hole 51a, which is a through-hole in the metal plate 51, is cylindrical, and its central axis extends in the normal direction of the metal plate 51. Note that FIGS. 3A and 3B show some of the resonant elements and holes 51a in the frequency selective surface 8, and the number of resonant elements and holes 51a arranged in the x-axis direction and the y-axis direction does not matter.

[0031] 5A to 5K are diagrams showing the results of a simulation of the frequency characteristics of S parameters for frequency selective surface 8. In the simulation, metal plate 51 is an aluminum plate having a thickness of 0.5 mm, dielectric plates 52 and 53 have a thickness of 0.254 mm, and a relative dielectric constant ε r was 2.19. In addition, in metal plate 51, holes 51a with a diameter of 2.0 mm were arranged infinitely every 2.3 mm in the x-axis direction and the y-axis direction. In addition, metal foils 54 and 55 were copper foil, holes 54a and 55a were annular with an outer diameter of 1.8 mm and an inner diameter of 1.4 mm, and the centers of annular holes 54a and 55a were positioned on the central axis of cylindrical hole 51a.

[0032] FIG. 5A is a graph showing the wideband characteristics of the S parameters when radio waves polarized in the x-axis direction are incident from the vertical direction of the frequency selective surface 8. Since it is desired that radio waves in the range of 59 to 62 GHz are transmitted through the frequency selective surface 8, dashed lines are drawn at 59 and 62 GHz in each of the graphs in FIG. 5A to FIG. 5K. As shown in FIG. 5A, in the target frequency band, the S 11 is a sufficiently low value, and S 21 is near 0 dB. 11 denotes the intensity of the reflection, and S 21 indicates the transmission characteristics, and it can be seen from FIG. 5A that the frequency selective surface 8 functions as a band-pass filter for the target frequency band.

[0033] 5B and 5C are graphs showing the frequency characteristics of S parameters when radio waves polarized in the x-axis direction and the y-axis direction are incident from the perpendicular direction of the frequency selective plate 8, respectively. The frequency selective plate 8 shown in FIGS. 3A and 4 has multiple resonant elements periodically arranged with four-fold symmetry. That is, the multiple resonant elements (multiple holes 51a and multiple annular holes 54a, 55a) are arranged with four-fold symmetry with respect to an axis perpendicular to the planar direction of the frequency selective plate 8 and passing through a representative point (e.g., the center or center of gravity) of a certain hole 51a. Therefore, as shown in FIGS. 5B and 5C, the frequency characteristics of S parameters are similar whether the polarization is in the x-axis direction or the y-axis direction.

[0034] 5D, 5F, 5H, and 5J are graphs showing the frequency characteristics of the S parameters when horizontally polarized (TE) radio waves are incident on the frequency selective surface 8. Also, FIGS. 5E, 5G, 5I, and 5K are graphs showing the frequency characteristics of the S parameters when vertically polarized (TM) radio waves are incident on the frequency selective surface 8. The incident angle of the radio waves is set to 10 degrees in FIGS. 5D and 5E, 20 degrees in FIGS. 5F and 5G, 30 degrees in FIGS. 5H and 5I, and 40 degrees in FIGS. 5J and 5K. In this simulation, the incident plane of the radio waves was set to the x-axis direction. As can be seen from the simulation results in FIGS. 5A to 5K, the frequency selective surface 8 exhibits high S 21 is close to 0 dB, and S 11 is S 21 is a value that is sufficiently low compared to the value of the frequency selective plate 8. Therefore, it was confirmed that the frequency selective plate 8 functions as a bandpass filter for the target frequency band, regardless of the incident angle of the radio wave or the direction of polarization. Therefore, it was confirmed that by configuring the housings 31 to 33 of the links 11 to 13 using the frequency selective plate 8, wireless communication in the target frequency band (59 to 62 GHz) can be achieved between the base-end side antenna 3 and the link-side antennas 21 to 23, and the influence of noise in other frequency bands can be reduced.

[0035] Although the case where the holes 51a of the frequency selective plate 8 are cylindrical has been described above, the holes 51a may be, for example, polygonal prisms (e.g., square prisms, regular hexagonal prisms, regular octagonal prisms, etc.) whose axes extend in the normal direction of the metal plate 51, or may have other shapes. In this case, the holes 54a, 55a of the metal foils 54, 55 may also have shapes corresponding to the holes 51a. Even in this case, it is preferable that the frequency selective plate 8 has four-fold symmetry, as when the holes 51a are cylindrical.

[0036] [Dyesymmetric frequency selective surface] FIG. 6A is a diagram showing another example of a frequency selective plate 9 in which a plurality of resonant elements, each having a hole of the same shape, are periodically arranged. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6A. As shown in FIG. 7, the frequency selective plate 9 may include a metal plate 61 having a plurality of periodically arranged holes 61a, a pair of dielectric plates 62, 63 respectively arranged on both sides of the metal plate 61, and a pair of metal foils 64, 65 respectively provided on the outer surfaces of the pair of dielectric plates 62, 63, i.e., on the side opposite the metal plate 61, and having holes 64a, 65a at positions corresponding to the hole 61a. In the frequency selective plate 9, each resonant element is composed of a hole 61a and a metal foil 64, 65 having a hole 64a, 65a, which is respectively arranged at the opening of the hole 61a via the dielectric plates 62, 63.

[0037] 6B is a plan view showing the metal plate 61. As shown in FIGS. 6B and 7, each hole 61a, which is a through-hole in the metal plate 61, has a quadrangular prism shape (a rectangular parallelepiped shape). Four side surfaces of the quadrangular prism shape extend in the normal direction of the metal plate 61. Note that FIGS. 6A and 6B show some of the resonant elements and holes 61a in the frequency selective surface 9, and the number of resonant elements and holes 61a arranged in the x-axis direction and the y-axis direction does not matter.

[0038] 8A to 8J are diagrams showing the results of a simulation of the frequency characteristics of S parameters for the frequency selective surface 9. In the simulation, the metal plate 61 is an aluminum plate having a thickness of 0.5 mm, the dielectric plates 62 and 63 have a thickness of 0.254 mm, and the relative dielectric constant ε r was 2.19. In addition, in metal plate 61, holes 61a, each 1.0 mm long in the x-axis direction and 2.4 mm long in the y-axis direction, were arranged infinitely every 2.1 mm in the x-axis direction and infinitely every 2.6 mm in the y-axis direction. In addition, metal foils 64, 65 were copper foils, and holes 64a, 65a were rectangular, each 0.2 mm long in the x-axis direction and 2.1 mm long in the y-axis direction, and the centers (centers of gravity) of rectangular holes 64a, 65a were aligned with the center (center of gravity) of square prism-shaped hole 61a in plan view.

[0039] 8A to 8J are graphs showing the frequency characteristics of S parameters when radio waves are incident on the frequency selective plate 9. In FIGS. 8A to 8J, dashed lines are drawn at 59 and 62 GHz. FIGS. 8A and 8B are graphs showing the frequency characteristics of S parameters when radio waves polarized in the x-axis direction and the y-axis direction are incident on the frequency selective plate 9 from the perpendicular direction. In the frequency selective plate 9 shown in FIGS. 6A and 7, multiple resonant elements are periodically arranged with two-fold symmetry. That is, multiple resonant elements (multiple holes 61a) are arranged with two-fold symmetry with respect to an axis perpendicular to the planar direction of the frequency selective plate 9 and passing through a representative point (e.g., the center or center of gravity) of a certain hole 61a. Therefore, as shown in FIGS. 8A and 8B, the frequency selective plate 9 transmits waves polarized in the x-axis direction but does not transmit waves polarized in the y-axis direction.

[0040] 8C, 8E, 8G, and 8I are graphs showing the frequency characteristics of the S parameters when horizontally polarized radio waves (TE waves) are incident on the frequency selective surface 9. Also, FIGS. 8D, 8F, 8H, and 8J are graphs showing the frequency characteristics of the S parameters when vertically polarized radio waves (TM waves) are incident on the frequency selective surface 9. The incident angle of the radio waves is set to 10 degrees in FIGS. 8C and 8D, 20 degrees in FIGS. 8E and 8F, 30 degrees in FIGS. 8G and 8H, and 40 degrees in FIGS. 8I and 8J. In this simulation, the incident plane of the radio waves was set to the x-axis direction. As can be seen from the simulation results in FIGS. 8A to 8J, the frequency selective surface 9 exhibits S parameters for radio waves polarized in the x-axis direction in the target frequency band, regardless of the incident angle of the radio waves. 21 is close to 0 dB, and S 11 is S 21 The value is sufficiently low compared to the value of S 11 is close to 0 dB, and S 21 is S 11is a sufficiently low value compared to the value obtained by the calculation. Therefore, it was confirmed that the frequency selective plate 9 functions as a bandpass filter for the target frequency band for radio waves polarized in the x-axis direction, regardless of the incident angle of the radio waves, but attenuates the target frequency band for radio waves polarized in the y-axis direction. Therefore, when configuring the housings 31-33 of the links 11-13 using the frequency selective plate 9, it is preferable to configure it so that wireless communication is performed between the base-end side antenna 3 and the link-side antennas 21-23 using radio waves polarized in the x-axis direction. For example, if the base-end side of the link mechanism 1 does not rotate relative to the base 2, such wireless communication can be achieved.

[0041] Although the case where the holes 61a of the frequency selective plate 9 are rectangular prism-shaped has been described here, the holes 61a may be, for example, elliptical prism-shaped with their axes extending in the normal direction of the metal plate 61, or may have other shapes. Even in this case, the frequency selective plate 9 may have two-fold symmetry, just as when the holes 61a are rectangular prism-shaped.

[0042] Although examples of frequency selective plates with four-fold symmetry and two-fold symmetry have been described, various frequency selective plates that transmit a desired frequency band can be used. For example, frequency selective plates with rotational symmetry other than four-fold symmetry or two-fold symmetry (e.g., six-fold symmetry) may be used for the housings 31 to 33. A frequency selective plate in which multiple resonant elements have six-fold symmetry may have, for example, a metal plate in which cylindrical or regular hexagonal prism-shaped holes are arranged in six-fold symmetry. Also, frequency selective plates with layer structures different from those shown in FIGS. 4 and 7 may be used. Furthermore, for example, if it is desired to improve the strength of the frequency selective plate, the metal plate in the frequency selective plate may be made thicker.

[0043] Next, a brief description will be given of the operation of the link mechanism control device 100. When controlling each of the joints 41 to 43 of the link mechanism 1, the control unit 5 transmits control signals for controlling the actuation of each of the joints 41 to 43 to the access point 4. The access point 4 then transmits these control signals via the base-side antenna 3. The transmitted control signals pass through the frequency selective plates of the housings 31 to 33, are received by the link-side antennas 21 to 23, and are then passed to the control circuits via the communication means of each of the links 11 to 13. The control circuits then control the actuation means in accordance with the control signals. The control circuits of each of the links 11 to 13 also acquire sensing results from sensors such as rotary encoders and transmit them via the communication means and the link-side antennas 21 to 23. These sensing results pass through the frequency selective plates of the housings 31 to 33, are received by the base-side antenna 3, and are passed to the control unit 5 via the access point 4. The control unit 5 uses the received sensing results to generate and transmit new control signals. In this way, the control unit 5 controls the operation of the link mechanism 1.

[0044] As described above, in the link mechanism 1 according to this embodiment, by disposing the link-side antennas 21-23 inside the housings 31-33 in the links 11-13, the link-side antennas 21-23 can be protected by the housings 31-33. Because the housings 31-33 are constructed using frequency selective plates with metal plates, the safety of the link-side antennas 21-23 can be improved compared to when the link-side antennas are housed in a plastic radome. Furthermore, by constructing the housings 31-33 using frequency selective plates that transmit the frequency bands used in wireless communications using the link-side antennas 21-23, the effect of radio wave shielding by the housings 31-33 can be reduced, enabling appropriate wireless communications between the base-side antenna 3 and the link-side antennas 21-23. Furthermore, by constructing the housings 31-33 using frequency selective plates with metal plates, the strength of the links 11-13 can be improved compared to when the housings 31-33 are constructed from plastic. Furthermore, the hole-type frequency selective surface functions as a bandpass filter that transmits only the desired frequency band, which also has the effect of reducing noise from RF substrates and the like.

[0045] While it is conceivable to place only the antenna outside the housing in a link, when transmitting and receiving short-wavelength radio waves such as millimeter waves, the loss in the cable connecting the communication means and the antenna increases, and the cost of the cable also increases. Furthermore, since there are general-purpose products that integrate antennas and communication means, there is a desire to configure a link mechanism using such general-purpose products. Because it is difficult to place only the antenna outside the housing, it is preferable to place the link-side antennas 21-23 inside the housings 31-33 of the frequency selective board, as in the link mechanism 1 of this embodiment.

[0046] Furthermore, by having the link mechanism 1 have one or more link-side antennas provided on at least one of the multiple links 11 to 14, it is possible to reduce the amount of wiring passing through the joints at least in some of the joints of the link mechanism 1, which has the advantage of enabling a reduction in wiring throughout the link mechanism 1 as a whole.

[0047] Furthermore, for example, by wirelessly supplying power to the joints of the link mechanism 1, if all the wiring in the joints is removed, the range of motion is not limited, and the joints can rotate any number of times in one direction. Furthermore, as the number of wires is reduced, the weight of the link mechanism 1 can be reduced, and each joint can be rotated with less torque, which also contributes to energy conservation.

[0048] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0049] 1 Link mechanism 8, 9 Frequency selective plates 11, 12, 13, 14 Links 21, 22, 23 Link side antenna 31, 32, 33, 34 Housing 100 Link mechanism control device

Claims

1. a link mechanism including a plurality of links connected by joints driven by a driving means, and one or more link-side antennas provided on at least one of the plurality of links; one or more base-end antennas provided around the base end of the link mechanism; an access point that wirelessly transmits a control signal from the one or more base-side antennas to each of the one or more link-side antennas; a control unit that controls transmission of a control signal by the access point; The joints of the link mechanism are driven based on the control signal, Among the plurality of links, the link provided with the link-side antenna has a housing of a frequency selective board that transmits a frequency band used in wireless communication using the link-side antenna, and the link-side antenna is disposed within the housing; a link mechanism control device, wherein the one or more base-end side antennas are arranged so that, when each joint of the link mechanism is at any angle, each of the one or more link-side antennas and the one or more base-end side antennas can communicate wirelessly in line of sight when the frequency selective plate is ignored.

2. 2. The link mechanism control device according to claim 1, wherein the plurality of resonant elements are periodically arranged in four-fold or six-fold symmetry on the frequency selective surface.

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