Rotation drive device, rotation drive method, rotation drive program, and antenna device

Abstract

To contribute to obtaining an angle detection value with higher accuracy than that limited by an error even when an angle is detected by using a phase detection device such as an encoder for outputting a signal including a discrete pulse.SOLUTION: A rotation drive device is provided including a rotation angle detection device, a speed reducer, a rotation device, and a direction detection device. The rotation angle detection device detects a rotation direction and a rotation amount of a motor that is supplied with electric power and rotationally drives a first rotation shaft. The speed reducer reduces rotation speed of the rotationally driven first rotation shaft and rotationally drives a second rotation shaft. The rotation device is rotationally driven by the second rotation shaft whose rotation speed is reduced, and rotationally drives an object whose direction is defined. The direction detection device detects a direction defined with respect to the object.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] The present disclosure relates to a rotational drive device, a rotational drive method, a rotational drive program, and an antenna device.

Background Art

[0002] In order to communicate with a target such as a moving body such as an automobile or a flying body such as an artificial satellite, or to detect the position where the target exists, an antenna (aerial) having directivity such as a parabolic antenna and a Yagi antenna is used. In this case, it is necessary to align the direction in which the antenna exhibits the highest gain with the direction in which the target exists. To meet this requirement, a method is adopted in which the directivity direction of the antenna is detected, and based on the detected direction, the directivity direction of the antenna is aligned with the direction of the target. In order to detect the direction of an antenna having directivity (directional antenna), a method using pulses obtained from an encoder attached to the rotational drive shaft of a speed reducer of a motor that rotates this antenna at a known rotational speed is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Note that the disclosure of the above prior art documents is incorporated herein by reference. The following analysis was made by the present inventors.

[0005] In the apparatus for detecting an angle by the method described above, instead of an encoder that outputs an analog signal, an encoder that outputs a signal including discrete pulses may be used. Such an encoder detects and quantizes the rotation angle of the rotation drive shaft of the antenna by optical or mechanical means, and outputs a signal including a discrete number of pulses corresponding to the quantized angle. Therefore, when using an encoder, the resolution of the detected direction of the antenna is limited by the quantization error for one step of the encoder and the error of the encoder itself. Therefore, even when detecting the direction of the antenna using the signal from the encoder, it is desirable to detect the direction of the antenna with higher accuracy than the accuracy limited by the quantization error of the encoder and the error of the encoder itself.

[0006] An object of the present disclosure is to contribute to obtaining an angle detection value with higher accuracy than the accuracy limited by the error even when detecting an angle using a phase detection device such as an encoder that outputs a signal including discrete pulses.

Means for Solving the Problem

[0007] In a first aspect of the present disclosure, a rotation drive device is provided that includes a first rotation angle detection device, a speed reducer, a rotation drive device, and a direction detection device. The first rotation angle detection device detects the rotation direction and the amount of rotation of a motor that is supplied with power and rotates a first rotation shaft. The speed reducer reduces the rotation speed of the rotation-driven first rotation shaft and rotates a second rotation shaft. The rotation drive device is rotationally driven by the second rotation shaft whose rotation speed has been reduced, and rotationally drives an object whose direction is defined. The direction detection device detects the direction defined for the object based on the detected rotation direction and the amount of rotation of the motor.

[0008] In a second aspect of the present disclosure, a rotational driving method is provided that includes a rotation angle detection step, a deceleration step, a rotational driving step, and a direction detection step. The rotation angle detection step detects the rotational direction and the amount of rotation of a motor that is powered to rotationally drive a first rotating shaft. The deceleration step decelerates the rotational speed of the rotationally driven first rotating shaft to rotationally drive a second rotating shaft. The rotational driving step rotationally drives an object, whose direction is defined, by the second rotating shaft whose rotational speed has been decelerated. The direction detection step detects the direction defined for the object based on the detected rotational direction and the amount of rotation of the motor.

[0009] In a third aspect of the present disclosure, in the rotational driving device provided according to the first aspect of the present disclosure, a rotational driving program is provided that includes a direction calculation process and a direction acquisition process. The direction calculation process calculates the direction defined for the object from the rotational direction and the amount of rotation detected by the rotation angle detection device. The direction acquisition process acquires the direction defined for the object, which is detected by the direction detection device.

[0010] In a fourth aspect of the present disclosure, an antenna device is provided that includes a first rotation angle detection device, a first speed reducer, a first rotation drive device, a first direction detection device, a second rotation angle detection device, a second speed reducer, a second rotation drive device, and a second direction detection device. The first rotation angle detection device detects the azimuth angle component of the rotation direction and the rotation amount of a first motor that is supplied with power to rotationally drive a first rotation shaft. The first speed reducer reduces the rotation speed of the rotationally driven first rotation shaft to rotationally drive a second rotation shaft. The first rotation drive device is rotationally driven by the second rotation shaft whose rotation speed has been reduced, and rotationally drives an antenna whose direction is defined. The first direction detection device detects the azimuth angle component of the direction defined for the antenna based on the detected rotation direction and rotation amount of the first motor. The second rotation angle detection device detects the elevation angle component of the rotation direction and the rotation amount of a second motor that is supplied with power to rotationally drive a third rotation shaft. The second speed reducer reduces the rotation speed of the rotationally driven third rotation shaft to rotationally drive a fourth rotation shaft. The second rotation drive device is rotationally driven by the fourth rotation shaft whose rotation speed has been reduced, and rotationally drives an antenna whose direction is defined. The second direction detection device detects the elevation angle component of the direction defined for the antenna based on the detected rotation direction and rotation amount of the second motor.

Effect of the Invention

[0011] Each aspect of the present disclosure contributes to obtaining an angle detection value with higher accuracy than the accuracy limited by the error, even when detecting an angle using a phase detection device such as an encoder that outputs a signal including discrete pulses.

Brief Description of the Drawings

[0012]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 4C

Figure 5

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the embodiments described below. In each drawing, the same or corresponding elements and processes are appropriately assigned the same reference numerals. Furthermore, the drawings are schematic, and it should be noted that the dimensional relationships between the elements in the drawings, the ratios of the elements, and the details of each process may differ from the dimensional relationships between the elements in the configuration of the present disclosure when implemented, the ratios of the elements, and the details of each process. Also, there may be parts where the dimensional relationships and the details of the processes differ between the drawings.

[0014] FIG. 1A is a diagram illustrating the configuration of the antenna device 1. As illustrated in FIG. 1A, the antenna device 1 includes an antenna main body 10, an antenna drive device 12 for azimuth, and an orbit calculation device 18 for both azimuth and elevation. The antenna main body 10 includes a directional antenna 100 and a pedestal 102. The antenna drive device 12 includes a motor drive device 120, a motor 122, rotary drive shafts 124, 128, 136, a speed reducer 126, a drive gear 130, a shaft gear 134, an encoder 138, and a drive control device 16. The drive control device 16 includes a direction acquisition device 160, an artificial satellite direction calculation device 162, and a control device 164. Hereinafter, for the sake of concretization and clarification of the description, a specific example is given where the rotation axis of the motor 122 is directly coupled to the rotary drive shaft 124, and the rotation angles, rotation speeds, and rotation directions of the motor 122 and the rotary drive shaft 124 coincide.

[0015] Note that, for example, in the motor 122, a first rotating disk (not shown) that rotates together with the rotation axis is attached to the rotation axis of the motor 122, and a second rotating disk (not shown) is fixed to the bracket. A part of these two rotating disks overlaps with each other, and a large number of fine slits are formed in each part of these two overlapping rotating disks. The motor 122 further includes, for example, a light source (not shown) such as an LED (Light Emitting Diode) that irradiates these two rotating disks with light, and a light receiving circuit (not shown) including a photodiode that detects the light that has passed through the slits of the rotating disk from the light source.

[0016] These two rotating disks, the light source, and the light-receiving circuit generate, each time the rotating shaft of the motor 122 rotates by a certain angle in either the positive or negative direction, one pulse each of the rotation of the rotating shaft and two types of pulses indicating its direction. The number of pulses in each of the two types of pulse signals each containing these two types of discrete pulses indicates the displacement amount of the rotation angle of the rotating shaft of the motor 122, and the phase relationship between these two types of pulse signals indicates the rotation direction of the rotating shaft of the motor 122. In this way, the motor 122 incorporates components of an optical rotary encoder that generates two types of pulse signals indicating the rotation angle and rotation direction of its rotating shaft. Also, as shown by the dotted line in FIG. 1A, the gear of the drive gear 130 and the gear of the shaft gear 134 are directly meshed and coupled, and the drive gear 130 rotationally drives the shaft gear 134.

[0017] The antenna device 1 directs the direction of the directional antenna 100 to the direction desired by the user of the antenna device 1, for example, the direction in which an object exists, by these components. Note that an antenna is also called an aerial, as is well known. Also, the directional antenna 100 is, for example, a parabolic antenna, a horn antenna, a stacked Yagi antenna, or a phased array antenna, and has a sharp directivity. The object to be tracked by the directional antenna 100 can be, for example, a celestial body in space, an artificial satellite moving in space, a flying object such as an airplane moving in the air, a vehicle moving on the ground, or a ship moving on the sea. In the following description, the case where the object to be tracked by the antenna device 1 is the artificial satellite 106 is taken as a specific example.

[0018] The direction of the directional antenna 100 is generally defined as the direction (direction of maximum directivity 104) in which the directional antenna 100 exhibits the highest gain. However, when the antenna device 1 is used for the purpose of removing interfering signals coming from a specific direction, or when dealing with signals that become minimal when facing each other, such as differential signals, the direction of the directional antenna 100 may be defined as the direction in which the directivity of the directional antenna 100 exhibits the lowest gain. Such a direction can be understood as the direction indicated by the null point where the gain shows a minimum value in terms of directivity.

[0019] Also, when the antenna device 1 is used to generate signals that become minimal, such as differential signals, when the direction of the directional antenna is exactly aligned with the direction in which the artificial satellite 106 exists, the direction of the directional antenna 100 may be defined as the direction in which the directivity of the directional antenna 100 exhibits the lowest gain. Note that the differential signal is a signal obtained, for example, by taking the difference between a pair of signals received by a pair of small antenna elements provided on the left and right of the antenna horn (directional antenna 100). Such a differential signal has the characteristic that its intensity becomes smallest when the directional antenna 100 faces the artificial satellite 106.

[0020] For tracking the artificial satellite 106, it is necessary to align both the azimuth (Azimuth; AZ) component and the elevation (Elevation; EL) component of the direction of maximum directivity 104 with the direction of the position where the artificial satellite 106 exists as seen from the directional antenna 100 of the antenna device 1. Hereinafter, so as not to complicate the description, the "azimuth component of the direction where the artificial satellite 106 exists as seen from the directional antenna 100 of the antenna device 1" will be simply described as the "direction of the artificial satellite 106". Therefore, when implemented, the antenna device includes an antenna drive device 12 that aligns the azimuth component of the angle of the directional antenna 100 with the direction of the artificial satellite 106, and an antenna drive device 12 with a similar configuration that aligns the elevation component with the direction of the artificial satellite 106.

[0021] However, for the sake of illustration, the antenna driving device 12 for aligning the elevation angle component of the directivity antenna 100 in the direction of the artificial satellite 106 is omitted. That is, in each figure, the antenna device 1 is shown as if it only includes the antenna driving device for aligning the azimuth angle component of the direction of the directivity antenna 100 in the direction of the artificial satellite 106. However, in reality, the antenna device 1 further has an antenna driving device for aligning the elevation angle component of the direction of the directivity antenna 100 in the direction of the artificial satellite 106. Also, hereinafter, in order to prevent the description from becoming complicated, the "azimuth angle component of the directivity direction 104 of the directivity antenna 100" is simply described as the "directivity direction 104 of the directivity antenna 100" or simply the "directivity direction 104". Further, in the following description, only the antenna driving device for aligning the azimuth angle component of the directivity antenna 100 with the azimuth angle component in the direction of the artificial satellite 106 is described, and the description of the antenna driving device (not shown) for aligning the elevation angle component with the elevation angle component in the direction of the artificial satellite 106 is omitted.

[0022] First, each component of the antenna device 1 will be described. In the antenna body 10, the pedestal 102 is attached to the base (not shown) of the antenna device 1 and supports the directivity antenna 100 in a movable state in the directivity direction 104. The directivity direction 104 of the directivity antenna 100 supported by the pedestal 102 is aligned with the direction of the artificial satellite 106 by the driving of the antenna driving device 12 and the drive control device 16.

[0023] The orbit calculation device 18 calculates, at regular time intervals, information indicating the position of the artificial satellite 106 in the latest or very near future based on the orbit information of the artificial satellite 106 in accordance with the operation of the user of the antenna device 1. Hereinafter, for the sake of simplicity of description, "the latest or very near future" is simply described as "the latest". The orbit calculation device 18 sequentially outputs the calculated information indicating the latest position of the artificial satellite 106 to the artificial satellite direction calculation device 162. Whether the orbit calculation device 18 calculates the position where the artificial satellite 106 exists at that time as the latest, or calculates the position where the artificial satellite 106 will exist in the very near future depends on the orbit of the artificial satellite 106 and the operating speeds of the respective components of the antenna device 1, etc.

[0024] When the information indicating the position of the artificial satellite 106 is the case where the artificial satellite 106 orbits the Earth, it indicates the position where the artificial satellite 106 exists with a predetermined accuracy. The position of the artificial satellite 106 is indicated, for example, by the (x, y, z) coordinates in the xyz orthogonal coordinate system with a predetermined position in the three-dimensional space as the reference (origin). As a specific example of such an xyz orthogonal coordinate system, the Earth-centered Earth-fixed orthogonal coordinate system ECEF (Earth Centered Earth Fixed) with the center of the Earth as the reference can be mentioned. The orbit calculation device 18 calculates, for example, the coordinates of the artificial satellite 106 in the Earth-centered Earth-fixed orthogonal coordinate system ECEF.

[0025] In the antenna drive device 12, the motor 122 can be a motor that rotationally drives the rotation drive shaft 124 at a continuous angle. In this case, electric power with continuously changing intensity is supplied from the motor drive device 120 to the motor 122, and the motor 122 rotationally drives the rotation drive shaft 124 in the positive or negative direction at a continuous angle.

[0026] Alternatively, the motor 122 can be a stepping motor that rotates the rotary drive shaft 124 in units of a predetermined angle. The two types of pulse signals output by the motor 122 indicate how many angles and in which direction (positive or negative) the rotary shaft of the motor 122 has rotated in units of this predetermined angle. In the following description, the "two types of pulse signals output by the motor 122" are also simply referred to as "pulse signals". Also, the "pulses included in each of the two types of pulse signals output by the motor 122" are also simply referred to as "pulses". In the following description, as a specific example, the case where the motor 122 is a stepping motor that rotates the rotary drive shaft 124 in units of, for example, 0.0001 (1 / 10000)° is given. Also, the two types of pulse signals output by the motor 122 described above indicate, in units of 0.0001°, how many times the rotary shaft of the motor 122 has rotated in either the positive or negative direction.

[0027] The motor drive device 120 supplies the motor 122 with first to fifth electric powers, for example, having five types of pulse-like waveforms that may have different phases from each other, according to a torque command input from the control device 164. Among these electric powers, the waveform of the first electric power continuously includes a plurality of pulses that rotate the rotary shaft (not shown) of the motor 122 by a predetermined unit for each cycle, regardless of the positive or negative direction of rotation. That is, for example, when the motor drive device 120 supplies the motor 122 with the first electric power for one pulse, the rotary shaft of the motor 122 rotates the rotary drive shaft 124 by 0.0001° in the positive or negative direction.

[0028] Also, the waveforms of the second to fourth electric powers are also pulse-like, and the rotation direction of the rotary shaft of the motor 122 is determined by these electric powers. The waveform of the second electric power and the waveform of the third electric power are inverted with respect to each other, and the waveform of the fourth electric power and the waveform of the fifth electric power are inverted with respect to each other. When the motor drive device 120 appropriately controls the phases of the second and third waveforms and the phases of the fourth and fifth waveforms according to the torque command input from the control device 164, the rotary shaft of the motor 122 rotates in the positive or negative direction.

[0029] The motor drive device 120 receives an input from the control device 164 of the drive control device 16, and supplies the motor 122 with the combination of the above-described five types of power according to a torque command for aligning the directivity direction 104 of the directional antenna 100 with the direction of the latest artificial satellite 106. As described above, the motor 122 rotationally drives the rotating shaft and the rotational drive shaft 124 by the power supplied from the motor drive device 120. Hereinafter, in order not to complicate the description, the combinations of the first to fifth powers are simply described as "power" unless otherwise specified.

[0030] The speed reducer 126 is driven by the rotational drive shaft 124, and reduces its rotational speed, for example, to 1 / 100 by a combination of gears or the like, and increases the torque. Further, the speed reducer 126 drives the rotational drive shaft 128. The drive gear 130 is rotationally driven by the rotational drive shaft 128. As shown by the dotted line in the figure, the gears of the drive gear 130 and the shaft gear 134 are directly engaged, and the drive gear 130 directly rotationally drives the shaft gear 134. The shaft gear 134, the pedestal 102 of the antenna body 10, and the encoder 138 are coupled via the rotational drive shaft 136. The shaft gear 134 rotationally drives the pedestal 102 of the antenna body 10 or a rotating shaft (not shown) that rotates the directional antenna 100 in the pedestal 102.

[0031] The pedestal 102 of the rotationally driven antenna body 10, or a rotating shaft (not shown) that rotates the directional antenna 100 in the pedestal 102, aligns the directivity direction 104 of the directional antenna 100 with the direction of the artificial satellite 106. On the other hand, the rotation of the shaft gear 134 is transmitted to the encoder 138 via the rotational drive shaft 136.

[0032] The encoder 138 is, for example, a 22-bit encoder, detects the rotation angle of the rotational drive shaft 136, that is, the absolute value of the azimuth angle component of the directivity direction 104, and generates a shaft angle signal indicating this absolute value as a numerical value with an accuracy of 22 bits. That is, the encoder 138 is about 0.0001 (≒ 360 / (2 22It detects the absolute value of the rotation angle of the rotation drive shaft 136 with a resolution of ))°, and outputs it as a shaft angle signal to the direction-of-pointing acquisition device 160.

[0033] A more detailed explanation will be given with a specific example. For example, when the directional antenna 100 is facing true north, the azimuth component of its pointing direction 104 is 0°, when it is facing true east, the azimuth component of its pointing direction 104 is 90°, when it is facing true south, the azimuth component of its pointing direction 104 is 180°, and when it is facing true west, the azimuth component of its pointing direction 104 is defined as 270°. In this case, the encoder 138 outputs a shaft angle signal indicating the numerical value 0 when the pointing direction 104 of the directional antenna 100 is true north, the numerical value (2 22 ) / 4 when it is true east, the numerical value (2 22 ) / 2 when it is true south, and the numerical value ((2 22 )×3) / 4 when it is true west to the direction-of-pointing acquisition device 160.

[0034] The direction-of-pointing acquisition device 160 of the drive control device 16 acquires the numerical value of the shaft angle signal input from the encoder 138 of the antenna drive device 12, converts it into a numerical value in the unit of "°" indicating the pointing direction 104 of the directional antenna 100, and stores it. Further, the direction-of-pointing acquisition device 160 outputs the stored pointing direction 104 to the control device 164.

[0035] Note that the encoder 138 may be composed of components as an optical rotary encoder included in the motor 122. In this case, the encoder 138 outputs a shaft angle signal including two types of signals indicating the rotation angle and the rotation direction of the pointing direction 104 of the directional antenna 100 to the direction-of-pointing acquisition device 160. The direction-of-pointing acquisition device 160 calculates the latest pointing direction 104 from these two types of signals included in the shaft angle signal and the last stored pointing direction 104, stores it, and further outputs it to the control device 164.

[0036] The satellite direction calculation device 162 processes the latitude, longitude, and altitude indicating the position of the directional antenna 100 and the coordinates of the latest satellite 106 in the Earth-centered, Earth-fixed orthogonal coordinate system ECEF input from the orbit calculation device 18. Through this processing, the satellite direction calculation device 162 calculates the direction from the position of the directional antenna 100 to the position of the latest satellite 106, that is, the direction indicating the position of the satellite 106. Further, the satellite direction calculation device 162 interpolates the transition of the direction of the satellite 106 within the time interval (for example, 1 second) of the output of the predicted value for each torque control interval (for example, 50 milliseconds) for the motor 122, and outputs the interpolation result to the control device 164.

[0037] The control device 164 processes the pointing direction 104 input from the pointing direction acquisition device 160 and the direction of the interpolated satellite 106 input from the satellite direction calculation device 162. Through this processing, the control device 164 calculates the displacement amount, rotation direction, and rotation speed of the rotation angle of the rotation drive shaft 124 to make the difference between the pointing direction 104 and the direction of the satellite 106 as close to 0 as possible. Further, the control device 164 generates a torque command for applying the calculated displacement amount of the rotation angle to the rotation drive shaft 124 at the calculated rotation direction and rotation speed, and outputs it to the motor drive device 120 of the antenna drive device 12. That is, the control device 164 controls the motor drive device 120 to make the pointing direction 104 of the directional antenna 100 and the direction of the satellite 106 coincide as much as possible.

[0038] The operation of the antenna device 1 will be described below. FIG. 1B is a flowchart illustrating the process S10 of the antenna device 1 illustrated in FIG. 1A. The process S10 includes the processes of S100 to S112. In the process S10, the above-described pulse signal that can be output by the motor 122 is not used.

[0039] The orbit calculation device 18 calculates the position of the artificial satellite 106 at specific times at regular time intervals. Further, the orbit calculation device 18 outputs information indicating the position of the artificial satellite 106 obtained as a result of the calculation to the artificial satellite direction calculation device 162 of the drive control device 16 as a predicted value of the position of the artificial satellite 106. For example, the calculation of the position of the artificial satellite 106 and the output of the predicted value by the orbit calculation device 18 are performed at 1-second intervals from the time when the artificial satellite 106 rises above the horizon of the Earth for the directive antenna 100 and becomes visible until the time when it sinks below this horizon and becomes invisible (S100).

[0040] The artificial satellite direction calculation device 162 calculates the latest direction of the artificial satellite 106 and outputs it to the control device 164 (S102). Further, the artificial satellite direction calculation device 162 interpolates the direction of the artificial satellite 106 and outputs the interpolated direction of the artificial satellite 106 to the control device 164 (S104).

[0041] The pointing direction acquisition device 160 acquires the numerical value of the shaft angle signal input from the encoder 138 of the antenna drive device 12, converts it into the pointing direction 104 of the directive antenna 100 and stores it, and further outputs it to the control device 164 (S106). The control device 164 generates a torque command to make the difference between the latest pointing direction 104 and the interpolated latest direction of the artificial satellite 106 as close to 0 as possible and outputs it to the motor drive device 120. The torque command generates the above-described combination of five types of electric power and includes information necessary to match the pointing direction 104 of the directive antenna 100 and the direction of the artificial satellite 106 (S108).

[0042] Each component of the antenna drive device 12 rotates the shaft in the azimuth direction of the mount 102 via the rotary drive shaft 136 so as to align the pointing direction 104 of the directive antenna 100 with the interpolated direction of the artificial satellite 106 according to the torque command (S110).

[0043] The control device 164 determines whether the pointing direction 104 input from the pointing direction acquisition device 160 matches the direction of the artificial satellite 106 interpolated in the process of S104 within the error range (S112). When the components of these azimuth angles match within the error range (Y in the process of S112), the antenna device 1 ends the process, and when they do not match (similarly N), the process returns to the process of S104. In the antenna device 1, the processes of S100 to S112 described above are repeated at every time interval (1 second) of the calculation of the position of the artificial satellite 106 by the orbit calculation device 18 and the output of the predicted value.

[0044] Since the angular resolution of the shaft angle signal output by the encoder 138 in the antenna device 1 described above is about 0.0001 (1 / 10000)°, the pointing direction 104 can also be adjusted to the direction of the artificial satellite 106 with a resolution of 0.0001°. In parallel with the processes described above, the antenna drive device 12 (not shown in FIG. 1A) performs a process for making the elevation angle component of the direction of the directive antenna 100 match the elevation angle component of the direction indicating the position of the artificial satellite 106.

[0045] Before the specific description of each embodiment of the present disclosure, problems that may occur in the antenna device 1 and problems that can be solved by each embodiment of the present disclosure will be described. When the above-described antenna device 1 performs tracking and control of the artificial satellite 106, it is necessary to accurately align the pointing direction 104 of the directive antenna 100 with the direction of the artificial satellite 106. Further, not only for artificial satellites orbiting the Earth, but also in space development such as deep space exploration and lunar exploration, it is necessary to align the pointing direction 104 of the directive antenna 100 with the direction of a more distant artificial satellite 106 or probe for communication or the like. In such a case, it is necessary to use a directive antenna 100 as a large-diameter parabolic antenna.

[0046] When the artificial satellite 106 is used for earth observation and data communication, it is required to obtain high-resolution images and videos from the artificial satellite 106, or faster data communication is required. For these applications, high-frequency signals with high frequencies, short wavelengths, and wide communication bands in the Ka band, Ku band, Q band, V band, etc. are used. The higher the frequency of the high-frequency signal, the longer the diameter of the directive antenna 100 when it is a parabolic antenna, the sharper the directivity of the directive antenna 100, and the narrower the width of the directivity. Therefore, in such a case, it is necessary to accurately align the direction 104 of the directive antenna 100 with the direction of the artificial satellite 106.

[0047] FIG. 1C is a diagram illustrating a graph showing the angle of the direction 104 of the directive antenna 100. Since the accuracy of the direction 104 of the directive antenna 100 is limited by the angular resolution, in order to improve the accuracy of the direction 104 of the artificial satellite 106, it is necessary to increase the angular resolution of the angle of the direction 104 of the artificial satellite 106. As illustrated in FIG. 1C, if the direction 104 of the directive antenna 100 moves at an ultra-low speed in a certain direction, the graph of the angle of the direction 104 of this directive antenna 100 will be in a stepped shape. The reason is that if the movement of the direction 104 of the directive antenna 100 is ultra-low speed, it takes a long time for the direction 104 to exceed its angular resolution.

[0048] Focusing on the flat part of such a graph, actually, although the direction 104 of the directive antenna 100 is changing little by little, to the user of the antenna device 1, it seems that there is no change in the direction 104 of the directive antenna 100. Even in this flat part, the antenna drive device 12 is changing the direction 104 of the directive antenna 100 little by little. However, due to the limit of the angular resolution of the angle detection device (encoder 138), to the user of the antenna device 1, the direction 104 of the directive antenna 100 seems as if it has not moved. In the antenna device 1, the resolution of the encoder 138 is nothing but the angle difference shown by the changing part of the graph of the angle of the stepped direction 104.

[0049] Further, the directivity direction 104 of the directional antenna 100 is detected by the encoder 138 and output to the directivity direction acquisition device 160 as an axis angle signal. The directivity direction acquisition device 160 acquires the numerical value of the axis angle signal, converts it into the directivity direction 104, and stores it. However, the stored directivity direction 104 of the directional antenna 100 may be different from the actual directivity direction 104 of the directional antenna 100. When moving the directivity direction 104 of the directional antenna 100, the rotation of the motor 122 is transmitted to the antenna body 10 via the gears included in the speed reducer 126, the drive gear 130, and the shaft gear 134, and the directional antenna 100 is rotated. These components are coupled by the rotation drive shafts 124, 128, 136, and the displacement amount and rotation direction of the rotation angle of the rotation drive shaft 136 are detected using the encoder 138 and can be used for controlling the directivity direction 104 of the directional antenna 100.

[0050] In the antenna body 10, for example, the directional antenna 100 is supported by a support shaft (AZ axis) in the azimuth direction provided on the pedestal 102 and a support shaft (EL axis) in the elevation direction. In this case, since the directivity direction 104 of the directional antenna 100 is obtained based on the rotation angles of the AZ axis and the EL axis, a rotation angle detection device such as the encoder 138 is attached to each of the AZ axis and the EL axis. If there is even a slight deviation between the rotation axes of the AZ axis and the EL axis and the rotation axes used for angle detection in each of the rotation angle detection devices, a burden is imposed on the axes of the rotation angle detection devices, which may cause a failure of the rotation angle detection devices.

[0051] Therefore, the rotation angle detection device is attached to the AZ axis and the EL axis provided on the gantry 102 via components such as bellows that can absorb the deviation between the rotation axes of the AZ axis and the EL axis and the rotation axes of the rotation angle detection devices attached to these axes. Alternatively, when it is necessary to attach a device other than the rotation angle detection device to at least one of these axes, a synchronous gear that rotates in synchronization with the rotation of the axis to which such a device is attached is attached, and further, it may be necessary to attach the rotation angle detection device to this synchronous gear.

[0052] As described above, the rotation angle detection device is attached to each of the AZ axis and the EL axis via a bellows or a synchronous gear or the like. In such a case, due to the bellows or the like, problems such as loosening of the attachment strength of the detection device to the AZ axis and the EL axis or backlash occurring in the synchronous gear attached to the rotation axis of the rotation angle detection device may occur. Such problems lead to errors in the pointing direction 104 of the directional antenna 100, data corruption of the detection results, large errors, or any of these. Further, such problems may cause further problems such as a discrepancy between the pointing direction 104 of the directional antenna 100 calculated in the antenna device 1 and the actual pointing direction 104 of the directional antenna 100. The embodiments of the present disclosure described below are devised and configured to solve the problems as described above.

[0053] [First Embodiment] Hereinafter, the antenna device 2 according to the first embodiment of the present disclosure will be described. FIG. 2A is a diagram illustrating a configuration of the antenna device 2 according to the first embodiment of the present disclosure. As illustrated in FIG. 2A, the antenna device 2 includes an antenna driving device 20 instead of the antenna driving device 12 of the antenna device 1 shown in FIG. 1A, and the antenna driving device 20 includes a driving control device 22 instead of the driving control device 16. The driving control device 22 has a configuration in which a direction calculation device 220 is added to the driving control device 16 and the control device 164 is replaced with the control device 224. In the antenna device 2, two types of pulse signals indicating the displacement amount and the rotation direction of the rotation axis of the motor 122 described above with reference to FIG. 1A are input from the motor 122 to the direction calculation device 220. The pulse signals input to the direction calculation device 220 are used to control the direction of the directional antenna 100.

[0054] In the antenna device 2, the direction acquisition device 160 acquires the numerical value of the shaft angle signal from the encoder 138, converts it into the direction 104 of the latest directional antenna 100, and stores it. Further, the direction acquisition device 160 outputs the stored direction 104 to the control device 224 and the direction calculation device 220.

[0055] The direction calculation device 220 calculates the amount of change and the direction of the angle of the direction 104 that have occurred since the direction 104 was last stored from the pulse signals output from the motor 122. Further, the direction calculation device 220 calculates, stores, and outputs the latest direction 104 to the control device 224 based on the last stored direction 104, the calculated amount of change and direction of the direction 104.

[0056] The control device 224 outputs a torque command to the motor drive device 120 to make the difference between the latest pointing direction 104 input from the pointing direction calculation device 220 and the direction of the interpolated artificial satellite 106 input from the artificial satellite direction calculation device 162 as close to 0 as possible. Further, the control device 224 stores the calculated latest pointing direction 104 input from the pointing direction acquisition device 160 and the pointing direction calculation device 220. The control device 224 determines whether a change has occurred between the pointing direction 104 from the pointing direction acquisition device 160 that was last stored and the latest pointing direction 104 from the pointing direction acquisition device 160.

[0057] When a change has occurred, the control device 224 stores the latest pointing direction 104 input from the pointing direction acquisition device 160 as the latest pointing direction 104 input from the pointing direction acquisition device 160 and the pointing direction calculation device 220. Further, the control device 224 outputs the latest pointing direction 104 input from the pointing direction acquisition device 160 to the pointing direction calculation device 220, causes it to be stored as the latest pointing direction 104 calculated by the pointing direction calculation device 220, and updates it.

[0058] Hereinafter, the processing of the antenna device 2 shown in FIG. 2A will be described. FIG. 2B is a flowchart exemplifying the processing of the antenna device 2 shown in FIG. 2A. As exemplified in FIG. 2B, the antenna device 2 performs the processing of S12 and S122 and S124 shown by dotted lines in the figure. The processing of S12 includes the processing of S100 to S104, S120, and S108 to S112. Note that the processing contents of S100 to S104 and S108 to S112 among the processing included in the processing S12 are the same as the processing contents of S100 to S104 and S108 to S112 included in the processing S10 shown in FIG. 1B. That is, the processing of the antenna device 1 and the processing of the antenna device 2 differ in the processing of S120, S122, and S124.

[0059] The antenna device 2 first performs the processes of S100 to S104. That is, the orbit calculation device 18 calculates a predicted value of the position of the artificial satellite 106 at a specific time (S100). The artificial satellite direction calculation device 162 calculates the latest direction of the artificial satellite 106 (S102). Further, the artificial satellite direction calculation device 162 interpolates the transition of the direction of the artificial satellite 106 (S104).

[0060] The pointing direction acquisition device 160 acquires the numerical value of the shaft angle signal input from the encoder 138, converts it into the latest pointing direction 104, and stores it. The pointing direction calculation device 220 processes the pulse signal input from the motor 122 and the last stored pointing direction 104, calculates the latest pointing direction 104, and stores it. The pointing direction acquisition device 160 and the pointing direction calculation device 220 output the latest pointing direction 104 to the control device 224. The control device 224 stores the pointing direction 104 input from the pointing direction acquisition device 160 and the pointing direction calculation device 220 (S120).

[0061] The control device 224 generates a torque command for making the difference between the latest pointing direction 104 and the interpolated latest direction of the artificial satellite 106 as close to 0 as possible (S108). Each component of the antenna drive device 20 rotates the azimuth angle direction axis of the pedestal 102 via the rotary drive shaft 136 so that the pointing direction 104 of the directional antenna 100 matches the interpolated direction of the artificial satellite 106 according to the torque command (S110).

[0062] The control device 224 determines whether or not the latest pointing direction 104 input from the pointing direction calculation device 220 and the direction of the artificial satellite 106 interpolated in the process of S104 match within the error range (S112). When these azimuth components match within the error range (Y in the process of S112), the antenna device 2 proceeds to the process of S122, and when they do not match (also N), it returns to the process of S104.

[0063] The control device 224 determines whether the latest pointing direction 104 input from the pointing direction acquisition device 160 in the process of S120 has changed from the pointing direction 104 last stored from the pointing direction acquisition device 160 (S122). When a change occurs in the latest pointing direction 104 (Y in the process of S122), the antenna device 2 proceeds to the process of S124. When no change occurs in the latest pointing direction 104 (N in the process of S122), the control device 224 stores the latest pointing direction 104 input from the pointing direction acquisition device 160 and the pointing direction calculation device 220 in the process of S120, and the antenna device 2 ends the process.

[0064] The control device 224 stores the latest pointing direction 104 input from the pointing direction acquisition device 160 in the process of S120 as the latest pointing direction 104 input from the pointing direction acquisition device 160 and the pointing direction calculation device 220. Further, the control device 224 outputs the latest pointing direction 104 input from the pointing direction acquisition device 160 in the process of S120 to the pointing direction calculation device 220 and updates it by storing it (S124). Note that also in the antenna device 2, similar to the antenna device 1 shown in FIG. 1A, the processes of S12, S122, and S124 described above are repeated at each time interval of the calculation of the position of the artificial satellite 106 by the orbit calculation device 18 and the output of the predicted value. Such repetition of the process is commonly performed in the following embodiments.

[0065] In the determination of S112, the value of the difference between the latest pointing direction 104 and the direction of the interpolated artificial satellite 106 may be the values at both ends of the error range. In such a case, whether the control device 224 determines that the latest pointing direction 104 and the direction of the interpolated artificial satellite 106 match or determines that these directions do not match is a problem in the implementation of the antenna device 2 and is not an essential difference.

[0066] The pointing direction 104 indicated by the shaft angle signal output from the encoder 138 attached to the rotation drive shaft 136 that changes the pointing direction 104 of the directional antenna 100 is a value corresponding to the absolute value of the actual pointing direction 104. In contrast, the amount of change and the direction of the angle of the pointing direction 104 calculated by the pointing direction calculation device 220 from the pulse signal input from the motor 122 are considered not to be values corresponding to the absolute value of the actual pointing direction 104, but relative values with respect to the pointing direction 104 at a certain time.

[0067] For these reasons, in the processes of S122 and S124, the control device 224 preferentially stores the latest pointing direction 104 input from the pointing direction acquisition device 160 over the latest pointing direction 104 input from the pointing direction calculation device 220, and further causes the pointing direction calculation device 220 to store it. By these processes, the accumulation of relative errors in the pointing direction 104 calculated by the pointing direction calculation device 220 is prevented. Note that it is also possible to modify the process of S122 so that the control device 224 performs the process of S124 only when the absolute value of the difference between the two latest pointing directions 104 input from the pointing direction acquisition device 160 and the pointing direction calculation device 220 is greater than a predetermined threshold value.

[0068] Taking as a specific example the case where the latest pointing direction 104 is 10.23° and the direction of the interpolated artificial satellite 106 is 10.24°, the processing of the antenna device 2 will be described in more detail. The encoder 138 can detect the angle with an accuracy of 0.0001°. In this case, the control device 224 supplies a first power including 10,000 pulses from the motor drive device 120 to the motor 122 to rotate the rotating shaft of the motor 122 by 1°. The reason is that although the rotating shaft of the motor 122 rotates by 1° due to the supply of this power, this rotation is decelerated to 1 / 100 by the speed reducer 126. Furthermore, the control device 224 needs to control the frequency of the pulses included in the first power so that the pointing direction 104 always matches the direction of the artificial satellite 106.

[0069] Also, in this case, the control device 224 needs to control the phases of the waveforms of the second and third powers and the phases of the waveforms of the fourth and fifth powers so that the pointing direction 104 changes in the positive direction from 10.23° to 10.24°. Thus, the control device 224 generates a torque command for controlling the waveforms of the first to fifth powers included in the power supplied from the motor drive device 120 to the motor 122.

[0070] Note that, as described above, in FIG. 2A, the illustration of the antenna drive device 20 that performs the same processing as for the azimuth angle component for the elevation angle component of the direction of the directional antenna 100 is omitted. That is, the antenna drive device 20, whose illustration is omitted in FIG. 2A, also performs the same processing as the processing described with reference to FIGS. 2A and 2B for the elevation angle direction of the direction of the directional antenna 100, as described in the description of the antenna device 2. Since the control of the elevation angle component of the direction of the directional antenna 100 by the antenna drive device not shown in this way is common to each embodiment, this description is omitted in the following embodiments.

[0071] The antenna device 1 shown in FIG. 1A is configured such that the pointing direction acquisition device 160 acquires the numerical value of the shaft angle signal output from the encoder 138 attached to the rotation drive shaft 136, converts it into the pointing direction 104 in units of "°", and stores it. Therefore, the accuracy of the alignment between the pointing direction 104 of the directional antenna 100 in the antenna device 1 and the direction of the artificial satellite 106 is limited to the accuracy of the detection of the rotation angle of the rotation drive shaft 136 by the encoder 138. That is, in the antenna device 1, the accuracy of the pointing direction 104 is limited to the detection accuracy of the rotation angle of the encoder 138, that is, 0.0001 (1 / 10000)°.

[0072] If it is desired to increase the accuracy of the alignment between the pointing direction 104 of the directional antenna 100 by the antenna device 1 and the position of the artificial satellite 106, it is necessary to increase the detection accuracy of the angle of the encoder 138. In order to increase the detection accuracy of the rotation angle, it is necessary to replace the encoder 138 with a more expensive and highly accurate encoder in the antenna device 1.

[0073] Also, in the antenna device 1, the detection error of the rotation angle of the rotation drive shaft 136 deteriorates also when there is a defect in the bellows used for attaching the encoder 138 to the rotation drive shaft 136 and when the encoder 138 fails to follow the rotation of the rotation drive shaft 136. Further, as causes of the error between the directivity direction 104 of the directive antenna 100 and the direction of the artificial satellite 106 in the antenna device 1, defects in the encoder 138 and improper attachment of the encoder 138 to the rotation drive shaft 136 are also conceivable. Thus, there are many causes of the detection error of the rotation angle of the rotation drive shaft 136 in the antenna device 1. That is, it is difficult for the user of the antenna device 1 to determine whether any one of these causes or a combination of two or more of these causes has deteriorated the detection error of the rotation angle of the rotation drive shaft 136.

[0074] Also, in the antenna device 1, the directivity direction 104 of the directive antenna 100 can be detected in units of 0.0001°. On the other hand, in the antenna device 2, the rotation shaft of the motor 122 is rotated in units of 0.0001° based on a torque command. This rotation is decelerated to 1 / 100 by the speed reducer 126 via the rotation drive shaft 124. Therefore, the rotation angles of the rotation drive shafts 128, 136 and the shaft gear 134 can be detected with a resolution of 0.000001 (1 / 1000000 = 1 / 10000 × 1 / 100; one millionth)°.

[0075] That is, according to the antenna device 2, the direction 104 of the directional antenna 100 can be aligned with the direction of the artificial satellite 106 with 100 times higher accuracy than that by the antenna device 1. Since the resolution of the encoder 138 alone is about 1 / 10000 as described above, if an attempt is made to obtain the accuracy of the direction 104 in the antenna device 2 with the encoder 138 alone, the resolution of the encoder 138 has to be increased by about 100 times. The manufacture of such an encoder is very difficult and even if it can be manufactured, it is very expensive. In contrast, the antenna device 2 can align the direction 104 with the direction of the artificial satellite 106 about 100 times more accurately than the antenna device 1 without requiring a difficult-to-manufacture and expensive encoder. That is, according to the antenna device 2, the artificial satellite 106 can be tracked more accurately than by the antenna device 1.

[0076] Hereinafter, a modified example of the antenna device 2 will be described. FIG. 2C is a diagram illustrating the configuration of an antenna device 24 obtained by modifying the antenna device 2 shown in FIG. 2A. As illustrated in FIG. 2C, the antenna device 24 includes an antenna drive device 26 instead of the antenna drive device 20 shown in FIG. 2A. The antenna drive device 26 has a configuration in which a rotation angle detection device such as an encoder 260 is attached to a rotation drive shaft 124 driven by a motor 122.

[0077] The encoder 260 outputs a shaft angle signal including a pulse indicating the rotation angle of the rotation drive shaft 124 to the direction-of-pointing calculation device 220. The direction-of-pointing calculation device 220 calculates the direction 104 from the shaft angle signal input from the encoder 260 and outputs it to the control device 224. Note that even if the resolution of the direction 104 by the pulses included in the shaft angle signal of the encoder 260 is different from the resolution of the direction 104 by the torque command output from the control device 224, it can be corrected by the calculation method in the direction-of-pointing calculation device 220. Therefore, the resolution of the direction 104 by the pulses included in the shaft angle signal output by the encoder 260 may be the same as or different from the resolution of the direction 104 by the torque command output by the control device 224.

[0078] Even with the antenna device 24 obtained by deforming the antenna device 2 in this way, the pointing direction 104 can be aligned with the direction of the artificial satellite 106 with the same accuracy as the antenna device 2. As described above, in the antenna device 24, it is not necessary to include components such as a rotating disk for the motor 122 to generate a pulse signal indicating the rotation angle and rotation direction of the rotation axis, etc.

[0079] [Second Embodiment] Hereinafter, the antenna device 3 according to the second embodiment of the present disclosure will be described. FIG. 3A is a diagram illustrating a configuration of the antenna device 3 according to the second embodiment of the present disclosure. As illustrated in FIG. 3A, the antenna device 3 has a configuration in which an abnormality display device 34 including a display device, an alarm device, etc. (not shown) is added to the antenna device 2 shown in FIG. 2A, and an antenna drive device 30 is provided instead of the antenna drive device 20 of the antenna device 2.

[0080] The antenna drive device 30 has a configuration in which a synchronous gear 140, an angle detection gear 142, and a rotation drive shaft 144 are added to the antenna drive device 20, and a drive control device 32 is provided instead of the drive control device 22. Note that in the antenna drive device 30, the encoder 138 is attached to the rotation drive shaft 144 via a bellows or the like. The drive control device 32 has a configuration in which an abnormality detection device 320 is added to the drive control device 22 shown in FIG. 2A.

[0081] In the antenna drive device 30, the synchronous gear 140 and the angle detection gear 142 have the same diameter and the same number of teeth, and as shown by the dotted line in FIG. 3A, these directly mesh with each other. The synchronous gear 140 is attached to the rotation drive shaft 136 and rotates at the same rotation speed as the shaft gear 134. The synchronous gear 140 and the angle detection gear 142 rotate at the same rotation speed, and the angle detection gear 142 rotationally drives the rotation drive shaft 144. The rotation of the angle detection gear 142 is transmitted to the encoder 138 attached to the rotation drive shaft 144.

[0082] Similar to the first embodiment, the encoder 138 outputs to the direction acquisition device 160 an axis angle signal indicating the azimuth angle of the direction of the directional antenna 100 in the direction of the axis 104.

[0083] The control device 224 outputs a torque command to the motor drive device 120 to make the difference between the latest direction of the axis 104 input from the direction calculation device 220 and the direction of the interpolated artificial satellite 106 input from the artificial satellite direction calculation device 162 as close to 0 as possible. Further, the control device 224 stores the latest direction of the axis 104 input from the direction acquisition device 160 and the direction calculation device 220. The control device 224 determines whether or not a change has occurred between the direction of the axis 104 from the direction acquisition device 160 that was last stored and the latest direction of the axis 104 from the direction acquisition device 160.

[0084] When a change has occurred and the absolute value of the difference between the latest direction of the axis 104 input from the direction acquisition device 160 and the direction calculation device 220 is less than a predetermined threshold value, the control device 224 stores the latest direction of the axis 104 input from the direction acquisition device 160 as the latest direction of the axis 104 input from the direction acquisition device 160 and the direction calculation device 220. Further, the control device 224 outputs the latest direction of the axis 104 input from the direction acquisition device 160 to the direction calculation device 220, stores it as the latest direction of the axis 104 calculated by the direction calculation device 220, and updates it.

[0085] When no change has occurred and the absolute value of the difference for verification input from the direction acquisition device 160 and the direction calculation device 220 is greater than or equal to a predetermined threshold value, the abnormality detection device 320 detects an abnormality and causes the content of the detected abnormality to be displayed on the abnormality display device 34 to show the user of the antenna device 3. Hereinafter, the latest direction of the axis 104 calculated by the direction calculation device 220 is also described as the direction of the axis 104 for verification.

[0086] The operation of the antenna device 3 will be described below. FIG. 3B is a flowchart for processing the operation of the antenna device 3 shown in FIG. 3A. As illustrated in FIG. 3B, the antenna device 3 performs the processes of S12, S122, S124 shown in FIG. 2B and the processes of S140 and S142. However, appropriate changes can be made to each process included in S12 according to the difference in the configurations of the antenna device 2 and the antenna device 3.

[0087] First, the components of the antenna device 3 perform the process of S12 shown in FIG. 2B. The control device 224 of the antenna device 3 determines whether the latest direction of arrival 104 input from the direction of arrival acquisition device 160 in the process of S120 (FIG. 2B) has changed from the direction of arrival 104 from the direction of arrival acquisition device 160 stored last (S122). If a change occurs in the latest direction of arrival 104 (Y in the process of S122), the control device 224 proceeds to the process of S124. If no change occurs in the latest direction of arrival 104 (N in the process of S122), the control device 224 stores the latest direction of arrival 104 input from the direction of arrival acquisition device 160 and the direction of arrival calculation device 220 in the process of S120 and proceeds to the process of S140.

[0088] The abnormality detection device 320 reads from the control device 224 the direction of arrival 104 from the direction of arrival acquisition device 160 stored last and the verification direction of arrival 104 from the direction of arrival calculation device 220 stored last. The abnormality detection device 320 determines whether the absolute value of the difference between the direction of arrival 104 from the direction of arrival acquisition device 160 stored last and the verification direction of arrival 104 is equal to or greater than a predetermined threshold value. If the absolute value of this difference is equal to or greater than the threshold value, the antenna device 3 proceeds to the process of S142. If the absolute value of this difference is less than the threshold value, the antenna device 3 ends the process (S140).

[0089] When the absolute value of the difference is equal to or greater than the threshold value, the abnormality detection device 320 determines that some abnormality has occurred in the components of the antenna device 3, and that a difference has occurred in these pointing directions 104. Therefore, the abnormality detection device 320 causes the abnormality display device 34 to display on the display that some abnormality has occurred in the components of the antenna device 3, or causes the alarm device to notify the user of the occurrence of the abnormality by light, sound, etc., to alert the user of the antenna device 3 (S142).

[0090] According to the antenna device 3 described above, the technical effects of the antenna device 2 are further achieved, together with the technical effects peculiar to the antenna device 3. That is, according to the antenna device 3, the pointing direction 104 can be aligned with the direction of the artificial satellite 106 with an accuracy 100 times that of the antenna device 1, as in the case of the antenna device 2, and moreover, when an abnormality occurs, the user can be notified of the abnormality.

[0091] [Third Embodiment] Hereinafter, an antenna device 4 according to a third embodiment of the present disclosure will be described. FIG. 4A is a diagram illustrating the configuration of an antenna device 4 according to the third embodiment of the present disclosure. As illustrated in FIG. 4A, the antenna device 4 includes an antenna drive device 40 instead of the antenna drive device 20 of the antenna device 2 shown in FIG. 2A, and the antenna drive device 40 includes a drive control device 42 instead of the drive control device 22. The drive control device 42 has a configuration in which a correction device 420 and a correction information storage device 422 are added to the drive control device 22.

[0092] The rotational movement given by driving the rotary drive shaft 124 by the motor 122 is ideally accurately decelerated by the reduction ratio in the speed reducer 126 and transmitted to the drive gear 130, and further transmitted to the shaft gear 134. However, in reality, an error caused by the meshing of the gears in the speed reducer 126 and the drive gear 130 occurs in the rotational movement of the shaft gear 134.

[0093] To explain this in more detail, in a pair of two meshing gears such as the drive gear 130 and the shaft gear 134, there are two states: a state where both gears mesh with each other at one tooth, and a state where both gears mesh with each other at two teeth. The amount of deflection that occurs in this pair of gears is greater when both gears mesh with each other at one tooth than when they mesh with each other at two teeth. Therefore, the rotational speed of the shaft gear 134, which is the destination of rotation transmission, is slower than the rotational speed of the drive gear 130, which is the source of rotation transmission. Conversely, when both gears mesh with each other at two teeth, the deflection is eliminated and the rotational speed of the shaft gear 134 increases.

[0094] Such unevenness in the rotational speed of the rotary drive shafts 128 and 136 occurs every time the gears mesh in the drive gear 130 and the shaft gear 134, and can cause an error in the pointing direction 104. The antenna device 4 is configured such that the correction device 420 reads a correction value from the correction information storage device 422 using the angle of the pointing direction 104 and corrects the number of pulses included in the pulse signal output from the motor 122 based on the read correction value.

[0095] FIG. 4B is a diagram illustrating a correction table stored in the correction information storage device 422 shown in FIG. 4A. The content of the correction table can be obtained, for example, as a result of actually operating the antenna device 4, simulating the operation of the antenna device 4, or calculating based on the structure of the antenna device 4. The angle (°) shown in FIG. 4B is the physical azimuth angle of the shaft gear 134, that is, the azimuth angle of the pointing direction 104 of the antenna 100. The value of this azimuth angle is defined as a value of 0° or more and less than 360° in the clockwise direction (from true north to true east), with the case where the pointing direction 104 is true north as the reference (0°).

[0096] More specifically, the angle value in the correction table shown in FIG. 4B is 0° when the pointing direction 104 faces true north, 90° when it faces true east, 180° when it faces true south, and 270° when it faces true west. When the antenna device 4 is implemented, the correction table includes values of 0° to 359.9° in units of 0.1° as the angle value of the pointing direction 104.

[0097] Note that the correction of the number of pulses using the correction table by the correction device 420 is continuously performed for each correction period at a fixed time interval (for example, 1 second). The correction device 420 reads, every 1 second, at the timing when the correction period starts, the pulse correction value corresponding to the angle of the pointing direction 104 from the correction table stored in the correction information storage device 422. Note that the pulse correction value indicates the number of pulses to be added to, or subtracted from, the number of pulses generated during this period, assuming that the number of pulses generated in one correction period is 1000. Further, the correction device 420, at the timing when the correction period ends, reduces the number of pulses and outputs it to the pointing direction calculation device 220 when the number of pulses generated during this correction period is 1000 or less, that is, when the change in the angle of the pointing direction 104 is about 0.1° or less. That is, when the value of the pulse correction value corresponding to the angle of the pointing direction 104 is A during this period and the number of pulses generated during this period is B, the number of pulses C to be added to, or subtracted from, the number of pulses generated during this period is given by the following formula (1).

[0098] C = A×(B / 1000) (1)

[0099] On the other hand, when the number of pulses generated in one correction period is greater than 1000, the correction device 420 obtains the pulse correction values for a plurality of angle divisions included in the correction table. The correction device 420 adds the obtained pulse correction value to, or subtracts it from, the number of pulses generated during this correction period, and outputs it to the pointing direction calculation device 220.

[0100] A specific example will be given for further explanation. For example, assume that the angle of the directivity direction 104 of the directive antenna 100 is 0.1°, and during this correction period, the angle of the directivity direction 104 of the directive antenna 100 changes about 0.35° to the right to become about 0.45°, and 3,500 pulses are generated. In this case, the correction device 420 reads from the correction table the correction values of +59 for the range of 0.1° to 0.2°, +95 for the range of 0.2° to 0.3°, +95 for the range of 0.3° to 0.4°, and +59 for the range of 0.4° to 0.5°.

[0101] The correction device 420 obtains +249 (= +59+(+95)+(+95)) as the correction value for the range of 0.1° to 0.4° from the correction table, and obtains the correction value +29.5 for the range of 0.4° to about 0.45° from the above formula (1). The correction device 420 adds the correction value 249 for the range of 0.1° to 0.4° and the correction value +29.5 for the range of 0.4° to 0.45° to obtain the correction value +278.5 during this correction period. The correction device 420 outputs 3,778.5 obtained by adding +278.5 to the number 3,500 of pulses generated during this correction period to the directivity direction calculation device 220.

[0102] In addition, when the angle of the directivity direction 104 includes a value of the second digit or less after the decimal point at the timing when the correction period starts, for example, by rounding the value of the second digit or less after the decimal point, the angle of this directivity direction 104 is set to a value including up to the first digit after the decimal point. Alternatively, in such a case, the pulse correction value is appropriately interpolated according to the value of the second digit or less after the decimal point of the angle of the directivity direction 104.

[0103] To explain in more detail, for example, at the timing when a certain correction period starts, assume that the angle of the directivity direction 104 of the directive antenna 100 is 0.1°, and during this correction period, the angle of the directivity direction 104 of the directive antenna 100 changes by approximately 0.1° to the right. If the number of pulses generated during this correction period is 1000 (B = 1000), the correction device 420 adds the correction value of the pulse correction value +59 (A = +59; C = +59×(1000 / 1000)) read from the correction table to this number of pulses 1000. The correction device 420 uses the corrected number of pulses 1059 (= 1000+(+59)) as the number of pulses after correction generated during this correction period and outputs it to the directivity direction calculation device 220.

[0104] Alternatively, for example, at the timing when a certain correction period starts, assume that the angle of the directivity direction 104 of the directive antenna 100 is 0.1°, and during this correction period, the angle of the directivity direction 104 of the directive antenna 100 changes by approximately 0.05° to the right. If the number of pulses generated during this correction period is 500 (B = 500), the correction device 420 adds the correction value +29.5 (C = +59×(500 / 1000)), which is obtained by subtracting the pulse correction value +59 (A = +59) read from the correction table from the number of pulses 500 included in the pulse signal, to the number of pulses 500. The correction device 420 uses the corrected number of pulses 529.5 (= 500+(+29.5)) as the number of pulses after correction generated during this correction period and outputs it to the directivity direction calculation device 220.

[0105] Alternatively, for example, at the timing when a certain correction period starts, assume that the angle of the directivity direction 104 of the directive antenna 100 is 0.3°, and during this correction period, the angle of the directivity direction 104 of the directive antenna 100 changes approximately 0.1° to the left. If the number of pulses generated during this correction period is 1000 (B = 1000), the correction device 420 subtracts the pulse correction value +95 (A = +95; C = +95×(1000 / 1000)) read from the correction table from the number of pulses 1000 included in the pulse signal. The correction device 420 uses the corrected number of pulses 905 (=1000-(+95)) obtained in this way as the corrected number of pulses generated during this correction period and outputs it to the directivity direction calculation device 220.

[0106] Alternatively, for example, at the timing when a certain correction period starts, assume that the angle of the directivity direction 104 of the directive antenna 100 is 0.9°, and during this correction period, the angle of the directivity direction 104 of the directive antenna 100 changes approximately 0.15° to the left and becomes approximately 0.75° from 0.9°. If the number of pulses generated during this period is 1500, the correction device 420 reads -95 from the correction table as the correction value for the range of 0.9° to 0.8°, and reads the correction value -95 as the correction value for the range of 0.8° to 0.7°. The correction device 420 obtains -47.5 from the correction value -95 for the range of 0.8° to 0.70° and the above formula (1). Further, the correction device 420 adds the correction value -95 for the range of 0.9° to 0.8° and the correction value -47.5 for the range of 0.8° to 0.75°. The correction device 420 uses the pulse correction value -142.5 (=(-95)+(-47.5)) obtained in this way, subtracts it from the number of pulses 1500 generated during this period, and uses 1642.5 (=1500-(-142.5)) as the corrected number of pulses generated during this correction period and outputs it to the directivity direction calculation device 220.

[0107] As described above, the correction device 420 reads out a pulse correction value corresponding to the angle of the pointing direction 104 at the time when the correction period per second starts from the correction table, and further increases or decreases the read pulse correction value according to the number of pulses generated in a certain period of time after this time. Further, when the angle of the pointing direction 104 changes to the right direction, the correction device 420 adds the increased or decreased correction value to the number of pulses generated in the one second from the start to the end of the correction period. Alternatively, when the angle of the pointing direction 104 changes to the left direction, the correction device 420 subtracts the increased or decreased correction value from the number of pulses generated in the one second from the start to the end of the correction period. In this way, the correction device 420 corrects the number of pulses included in the pulse signal by using the pulse correction value read from the correction table.

[0108] Hereinafter, the operation of the antenna device 4 will be described. FIG. 4C is a flowchart illustrating the processing of the antenna device 4 shown in FIG. 4A. As illustrated in FIG. 4C, the antenna device 4 includes the processing of S160 and S162 between the processing of S104 and the processing of S120 shown in FIG. 2B.

[0109] The correction device 420 calculates the direction of the artificial satellite 106 by the processing of S102 and S104. Then, when the pointing direction 104 is aligned with the calculated direction, the correction device 420 refers to the correction table (FIG. 4B) stored in the correction information storage device 422 by using the angle of the pointing direction 104 at a certain time as described above. By this reference, the correction device 420 acquires a pulse correction amount corresponding to the angle of the pointing direction 104 at a certain time and the angle of the pointing direction 104 generated by the angle of the pointing direction 104 per 0.1° (pulse number 1000) until a certain period of time (for example, one second) elapses from this time (S160).

[0110] If necessary, the correction device 420 increases or decreases the correction value obtained in the process of S160 in proportion to the number of pulses included in the pulse signal input until a certain time (1 second) elapses from a certain time. Further, when the angle of the pointing direction 104 changes to the right direction, the correction device 420 corrects by adding the correction value increased or decreased as necessary to the number of pulses included in the pulse signal input until a certain time elapses from a certain time. On the other hand, when the angle of the pointing direction 104 changes to the left direction, the correction device 420 corrects by subtracting the correction value increased or decreased as necessary from the number of pulses included in the pulse signal input until a certain time elapses from a certain time. The correction device 420 outputs the pulse signal with the corrected number of pulses to the pointing direction calculation device 220 (S162).

[0111] According to the antenna device 4, the number of pulses included in the pulse signal input from the motor 122 is corrected according to the angle of the pointing direction 104 at a certain time and the number of pulses input in a certain time from this time. Therefore, according to the antenna device 4, the pointing direction 104 can be calculated with higher accuracy than by the antenna devices 2 and 3.

[0112] [Information processing apparatus that can be used in the implementation of the embodiments of the present disclosure] Note that all or part of the functions of the components of the first to third embodiments of the present disclosure can be implemented by an information processing apparatus (computer) 5 described below. FIG. 5 is a diagram illustrating the configuration of an information processing apparatus 5 that can implement all or part of the functions of the components of the first to third embodiments of the present disclosure. As illustrated in FIG. 5, the information processing apparatus 5 includes a CPU (Central Processing Unit) 500, a main storage device 502, an auxiliary storage device 504, and an interface (IF) 506 that are interconnected via a bus so as to be able to input and output information. However, the information processing apparatus 5 may include hardware components other than those shown in FIG. 5, and the components of the information processing apparatus 5 may be distributed over a plurality of devices. That is, the configuration of the information processing apparatus 5 is not limited to the configuration shown in FIG. 5.

[0113] The CPU 500 is executed by the information processing apparatus 5 and executes instruction commands included in programs required for processing components such as each component of the drive control apparatus 16. The main storage device 502 includes storage elements such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and temporarily stores data used by the CPU 500 to execute programs.

[0114] The auxiliary storage device 504 includes non-volatile storage devices such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), and a flash memory, and stores programs executed by the CPU 500, etc., in the medium and long term. Note that the programs stored in the auxiliary storage device 504 can be provided and distributed as products stored in non-transitory computer-readable media such as magnetic storage media, CDs, and DVDs (non-transitory computer-readable medium).

[0115] The IF 506 provides an interface for input / output of information between the drive control apparatus 16, etc., and the motor drive apparatus 120, the encoder 138, etc.

[0116] As described above, each component of the antenna devices 1 to 4 can be realized by a program executed in the information processing apparatus 5, except for components that must be configured by hardware due to their nature. On the other hand, these components may be realized by dedicated hardware or by an appropriate combination of hardware and software (program) executed in the information processing apparatus 5. Also, as described above, since at least a part of each component of the antenna devices 1 to 4 can be realized by a program, the content of the processing executed by such a component can be grasped as a method.

[0117] The following forms are possible in this application, but are not limited thereto. [Appendix 1] A rotary drive device comprising a first rotation angle detection device, a speed reducer, a rotary drive device, and a direction detection device. The first rotation angle detection device detects the rotation direction and rotation amount of a motor that is supplied with power to rotationally drive a first rotation shaft. The speed reducer reduces the rotational speed of the rotationally driven first rotation shaft to rotationally drive a second rotation shaft. The rotary drive device is rotationally driven by the second rotation shaft whose rotational speed has been reduced, and rotationally drives an object whose direction is defined. The direction detection device detects the direction defined for the object based on the detected rotation direction and rotation amount of the motor. [Appendix 2] The rotary drive device and the direction detection device are attached via a gear that rotates with the same rotation amount as the rotary drive device in a direction corresponding to the rotation of the rotary drive device, according to the rotary drive device described in Appendix 1. [Appendix 3] The object is a directional antenna, and the direction defined for the antenna is the direction in which the antenna exhibits the greatest gain, according to the rotary drive device described in Appendix 1 or 2. [Appendix 4] The rotary drive device according to any one of Appendices 1 to 3 further includes a first direction calculation device that calculates the direction defined for the antenna from the rotation direction and rotation amount detected by the first rotation angle detection device, and a direction acquisition device that detects the direction defined for the antenna and acquired by the direction detection device. [Appendix 5] The rotary drive device according to any one of Appendices 1 to 4 further includes a motor drive device that supplies power to the motor to drive it, a second direction calculation device that calculates the direction indicating the position of the target object, and a control device that controls the motor drive device to drive the motor so as to align the direction defined for the object and the direction indicating the position of the target object. [Appendix 6] When there is a difference equal to or greater than a predetermined threshold between the direction calculated by the first direction calculation device and the direction acquired by the direction acquisition device, the rotation drive device according to any one of Appendices 1 to 5 sets the direction acquired by the direction acquisition device as the direction in which the object is actually facing. [Appendix 7] The rotation drive device according to any one of claims 1 to 6 further includes a correction device that corrects the direction calculated by the first direction calculation device based on a correction amount corresponding to the direction defined for the object. [Appendix 8] A rotation drive method including a rotation angle detection step, a deceleration step, a rotation drive step, and a direction detection step. The rotation angle detection step detects the rotation direction and rotation amount of a motor that is supplied with power to rotationally drive a first rotation shaft. The deceleration step decelerates the rotation speed of the rotationally driven first rotation shaft to rotationally drive a second rotation shaft. The rotation drive step rotationally drives an object whose direction is defined by the second rotation shaft whose rotation speed has been decelerated. The direction detection step detects the direction defined for the object based on the detected rotation direction and rotation amount of the motor. [Appendix 9] In the rotation drive device provided according to the first aspect of the present disclosure, a rotation drive program including a direction calculation process and a direction acquisition process. The direction calculation process calculates the direction defined for the object from the rotation direction and rotation amount detected by the rotation angle detection device. The direction acquisition process acquires the direction detected by the direction detection device and defined for the object. Note that this program can be distributed in the market by being stored in a non-temporary computer-readable recording medium such as a magnetic storage medium, CD, and DVD, or being distributed via a network. [Appendix 10] An antenna device comprising a first rotation angle detection device, a first speed reducer, a first rotation driving device, a first direction detection device, a second rotation angle detection device, a second speed reducer, a second rotation driving device, and a second direction detection device. The first rotation angle detection device detects the azimuth angle component of the rotation direction and the rotation amount of a first motor that is supplied with power and rotates a first rotation shaft. The first speed reducer reduces the rotation speed of the rotated first rotation shaft to rotate a second rotation shaft. The first rotation driving device is rotated by the second rotation shaft with a reduced rotation speed and rotates an antenna with a defined direction. The first direction detection device detects the azimuth angle component of the direction defined for the antenna based on the detected rotation direction and rotation amount of the first motor. The second rotation angle detection device detects the elevation angle component of the rotation direction and the rotation amount of a second motor that is supplied with power and rotates a third rotation shaft. The second speed reducer reduces the rotation speed of the rotated third rotation shaft to rotate a fourth rotation shaft. The second rotation driving device is rotated by the fourth rotation shaft with a reduced rotation speed and rotates an antenna with a defined direction. The second direction detection device detects the elevation angle component of the direction defined for the antenna based on the detected rotation direction and rotation amount of the second motor. It goes without saying that any combination of the forms according to the appendices of the present disclosure, or any combination of the elements described in each viewpoint and embodiment (including non-selection of some elements) can be made by those skilled in the art at any time according to the basic concept of the present disclosure.

[0118] The disclosures of the above-cited patent documents and the like are incorporated herein by reference. Within the scope of all disclosures (including the claims), further modifications and adjustments of the embodiments or examples can be made based on their basic technical concepts. Also, within the scope of all disclosures, various combinations or selections (including partial deletion) of various disclosure elements (including each element of each claim, each element of the embodiments or examples, each element of each drawing, etc.) are possible. That is, this disclosure naturally includes all disclosures including the claims, as well as various modifications and corrections that could be made by those skilled in the art according to the technical concept. In particular, for the numerical ranges described in this document, any numerical value or small range included within the range should be construed as specifically described even in the absence of separate description. Furthermore, the disclosed matters of the above patent documents are, if necessary, combined with the description matters of this document in accordance with the spirit of this disclosure and are regarded as being included in the disclosed matters of this application, either in part or in whole, as part of this disclosure.

Explanation of Reference Signs

[0119] 1 to 4, 24 Antenna devices 10 Antenna body 100 Directional antenna 102 Mount 104 Direction of pointing 106 Artificial satellite 12, 20, 26, 30, 40 Antenna drive devices 120 Motor drive device 122 Motor 124, 128, 136, 144 Rotation drive shafts 126 Reducer 130 Drive gear 134 Shaft gear 138, 260 Encoder 140 Synchronization gear 142 Angle detection gear 16, 22, 32, 42 Drive control devices 160 Direction-of-pointing acquisition device 162 Artificial-satellite direction calculation device 164, 224 Control devices 220 Direction Calculation Device 320 Abnormality Detection Device 420 Correction Device 422 Correction Information Storage Device 18 Orbit Calculation Device 34 Abnormality Display Device 5 Information Processing Device 500 CPU 502 Main Memory Device 504 Auxiliary Memory Device 506 Interface Device

Claims

1. A first rotation angle detection device that detects the rotation direction and rotation amount of a motor that is supplied with power and rotationally drives a first rotation shaft; A speed reducer that reduces the rotational speed of the rotationally driven first rotation shaft and rotationally drives a second rotation shaft; A rotation drive device that is rotationally driven by the second rotation shaft whose rotational speed has been reduced and rotationally drives an object whose direction is defined; A direction detection device that detects the direction defined for the object based on the detected rotation direction and rotation amount of the motor A rotation drive device comprising:

2. The rotation drive device and the direction detection device are attached via a gear that rotates with the same rotation amount as the rotation drive device in a direction corresponding to the rotation of the rotation drive device The rotation drive device according to claim 1.

3. The object is a directional antenna, The direction defined for the antenna is the direction in which the antenna exhibits the greatest gain The rotation drive device according to claim 1.

4. A first direction calculation device that calculates the direction defined for the antenna from the rotation direction and rotation amount detected by the first rotation angle detection device; A direction acquisition device that detects the direction defined for the antenna and acquires the direction detected by the direction detection device The rotation drive device according to claim 3, further comprising:

5. A motor drive device that supplies power to the motor and drives it; A second direction calculation device that calculates the direction indicating the position of the target; A control device that controls the motor drive device to drive the motor so as to align the direction defined for the object and the direction indicating the position of the target The rotation drive device according to claim 4, further comprising:

6. When there is a difference equal to or greater than a predetermined threshold between the direction calculated by the first direction calculation device and the direction acquired by the direction acquisition device, the control device sets the direction acquired by the direction acquisition device as the direction in which the object is actually facing The rotation drive device according to claim 5.

7. A correction device that corrects the direction calculated by the first direction calculation device based on a correction amount corresponding to the direction defined for the object The rotation drive device according to claim 5, further comprising:

8. A rotation angle detection step of detecting the rotation direction and rotation amount of a motor that is supplied with power and rotationally drives a first rotation shaft; A deceleration step of decelerating the rotational speed of the rotationally driven first rotation axis to rotationally drive a second rotation axis; A rotational drive step of rotationally driving an object that is rotationally driven by the second rotation axis whose rotational speed has been decelerated and whose direction is defined; A direction detection step of detecting a direction defined for the object based on the detected rotational direction and amount of rotation of the motor; A rotational drive method comprising the above.

9. A rotational angle detection device that detects the rotational direction and amount of rotation of a motor that is supplied with power to rotationally drive a first rotation axis; a speed reducer that decelerates the rotational speed of the rotationally driven first rotation axis to rotationally drive a second rotation axis; a rotational drive device that rotationally drives an object that is rotationally driven by the second rotation axis whose rotational speed has been decelerated and whose direction is defined; and a direction detection device that detects a direction defined for the object based on the detected rotational direction and amount of rotation of the motor. In the rotational drive device comprising: A direction calculation process for calculating a direction defined for the object from the rotational direction and amount of rotation detected by the rotational angle detection device; A direction acquisition process for acquiring a direction defined for the object, detected by the direction detection device; A rotational drive program comprising the above.

10. A first rotational angle detection device that detects the azimuth angle component of the rotational direction and amount of rotation of a first motor that is supplied with power to rotationally drive a first rotation axis; A first speed reducer that decelerates the rotational speed of the rotationally driven first rotation axis to rotationally drive a second rotation axis; A first rotational drive device that rotationally drives an antenna that is rotationally driven by the second rotation axis whose rotational speed has been decelerated and whose direction is defined; A first direction detection device that detects the azimuth angle component of the direction defined for the antenna based on the detected rotational direction and amount of rotation of the first motor; A second rotational angle detection device that detects the elevation angle component of the rotational direction and amount of rotation of a second motor that is supplied with power to rotationally drive a third rotation axis; A second speed reducer that decelerates the rotational speed of the rotationally driven third rotation axis to rotationally drive a fourth rotation axis; A second rotational drive device that rotationally drives an antenna that is rotationally driven by the fourth rotation axis whose rotational speed has been decelerated and whose direction is defined; A second direction detection device that detects the elevation angle component of the direction defined for the antenna based on the detected rotational direction and amount of rotation of the second motor; An antenna device comprising

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