JPH111941A - Antenna tracking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna tracking device which can track both antennas on the side of a control device and on the side of an operation machine and further can eliminate the need for a relay station. SOLUTION: An antenna 4 mounted at a radio transmitter 3 on the side of an operation machine radiates rotary beams by rotating an eccentric auxiliary reflector 43. An antenna on the side of a control device has the same constitution and both the antennas have different revolution speeds. The transmitter 3 is mounted on a pan head 5 so as to be turned horizontally and vertically. Control signals received by the antenna 4 are converted to AGC signals in a level sensing circuit and inputted into a microcomputer 76 through a band-pass filter 74. The microcomputer 76 calculates command signals for motors 52, 57 to track the antenna on the side of the control device based on revolution angles of the reflector 43 obtained by 2 counter 73 and the AGC signals. The control device has the same constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna tracking device used for remotely controlling a work machine.

[0002]

2. Description of the Related Art Civil engineering works in danger zones, for example, near volcanic activities where there is a risk of lava fall or pyroclastic flow, or underground sites where a rock fall may occur, are used because they are dangerous to human life. Generally, a working machine (eg, a hydraulic shovel) is driven remotely without an operator. In this remote operation, an operation device is provided in a remote place remote from the work site, and the operation of the operation device is converted into a radio wave and transmitted to the work machine to drive the work machine. In this case, when the distance between the operating device and the working machine is short, the operator of the operating device can operate the working machine visually or by using a telescope or a telephoto camera. In such a case, it becomes impossible to grasp the situation of the work place of the work machine. In this case, the work machine is provided with a camera, and the image of the work place taken by the camera is transmitted to the operation device as an image signal. There is a need.

[0003]

When the above image signal is transmitted over a distance of 2 to 3 km, a frequency in the 50 GHz band is used due to legal regulations. Usually, an aperture type antenna (parabolic antenna) is used. However, since the work machine constantly changes its direction and posture, generates large shaking and vibration, and the parabolic antenna has a sharp directivity, the signal from the work machine's parabolic antenna is received by the parabolic antenna on the operating device side. It is extremely difficult to do. Therefore, conventionally, a fixed relay station is provided close to the work machine, and transmission and reception with the operation device side are performed via the relay station. The installation of such a relay station not only increases the cost, but also when the installation of the relay station is impossible,
There has been a problem that remote control of the work machine becomes impossible.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, and to reliably track both antennas on the operating device side and the work machine side, thereby eliminating the need for a relay station. A tracking device is provided.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for transmitting and receiving a radio signal between a working machine and an operating device at a remote location from the working machine. In the device for operating the work machine, an antenna for transmitting / receiving a radio wave, a radio device for transmitting / receiving via the antenna, and a transmission / reception beam transmitted / received by the antenna are provided on the operation device side and the work machine side, respectively. Beam rotation means for rotating, rotation position detection means for detecting a rotation position of the beam rotation means, reception level detection means for detecting a level of a signal received by the radio device, and detection by the rotation position detection means Turns the antenna to the antenna of the other party based on the rotated position and the reception level detected by the reception level detection unit at that time. Provided with a control unit for controlled so, characterized in that a different rotational speed a rotational speed of the beam rotating means and the operating device side and the working machine side.

In the present invention, the transmission beam rotated by the beam rotation means is radiated from the work machine side and the operation device side by taking such means. The work machine receives the signal transmitted from the operation device by the wireless device via the antenna, and detects the signal level. Then, based on the rotational position of the rotating beam detected by the rotational position detecting means and the signal level detected by the receiving level detecting means at that time, the current attitude of the work machine side antenna is corrected, and Is directed (tracked) to the antenna on the operation device side. Exactly the same operation is performed on the operation device side, and eventually, bidirectional antenna tracking is performed. As a result, transmission and reception between the working machine in operation and the remote control device can be reliably performed, and the installation of a relay station is unnecessary.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIG. 1 is a block diagram of a transmitting / receiving apparatus including an antenna tracking device according to an embodiment of the present invention. Before explaining this figure, the relationship between the work machine and its operating device and the antenna provided in the working machine and the operating device will be described.

FIG. 2 is a diagram showing a working machine and its operating device. In this figure, A indicates a work machine, and B indicates an operating device. The two are separated from each other by, for example, 2 to 3 km, and the working machine cannot be seen from the operation device B. 1A is a transmission / reception device including an antenna tracking device installed in, for example, a cab of a work machine, and 1B is a transmission / reception device including an antenna tracking device provided in an operation device B. The work machine A is provided with a camera (CCD camera) Ca at a position where the work site can be clearly seen, for example, at the position of the operator's eyes when the operator gets into the cab. Each of the transmitting and receiving devices 1A and 1B has an antenna. Through these antennas, the work machine A mainly transmits an image signal of the camera Ca, receives an operation signal from the operation device B, and responds to the received signal. On the other hand, the operation device B mainly transmits an operation signal, receives an image signal from the work machine, converts the image signal into an image, grasps the state of the site, and performs necessary operation according to the state. Send a signal.

FIG. 3 is a diagram showing antennas provided in the transmitting / receiving apparatuses 1A and 1B shown in FIG. In this figure, 3 is a radio, 30 is a primary radiator, and 4 is an antenna. The antenna 4 includes a main reflector (parabolic antenna) 41 and a motor 4
2, a sub-reflector 43 rotated by the motor 42, an encoder 44 for detecting a rotational position of the motor 42,
And a support 4 for fixing these to the parabolic antenna 41
5. As is well known, the encoder 44 outputs two pulses having a phase difference of 90 degrees, and
It has the function of outputting one pulse at the reference position for each rotation.

The axis of the sub-reflector 43 is
Is connected to a rotating shaft of the motor 42 along the focus of 1 inclined as small an angle to the axis x ₀ perpendicular thereto (are exaggerated inclination in the drawing) the axis x _1. In a commonly used antenna, only the sub-reflector 43 is fixed to the parabolic antenna 41, and a radio wave (beam) radiated from the primary radiator 30 is reflected by the sub-reflector 43 as shown by an arrow, and The light is reflected by the antenna 41 and radiated into space. On the other hand, in the present embodiment, the sub-reflector 43 is fixed to the rotation axis of the motor 42 at an angle as described above and is rotated by the motor 42, so that the beam radiated from the parabolic antenna 41 is It becomes a rotating beam whose radiation direction changes with time. This rotating beam is shown in FIG.

FIG. 4 shows a rotating beam. Figure 4 (a) is a diagram viewed rotating beam from the side (Fig. 3 the same direction), the central axis S ₀ of the rotating beam parabolic antenna
Rotate around. S ₁ and S ₂ indicate beams at a certain point in time. FIG. 4B shows a line IVb-I of FIG.
FIG. 5 is a cross-sectional view along Vb, where the beam is
It moves on the solid line circumference with time. The movement of the beam is synchronized with the rotation of the motor 42, and its position on the circumference is detected based on the output signal of the encoder 44. Secondary reflector 43
The deflection of the beam generated by the rotation is selected to be smaller than the half value directivity angle of the parabolic antenna used. For example, in the case of a wireless device of 50 GHz, 30c
Since the half value directivity angle of the m antenna is 1.5 degrees, the beam deflection in this case is made smaller than 1.5 degrees.

Here, the configuration of FIG. 1 will be described. FIG. 1 is a diagram showing a transmitting / receiving device 1A on the work machine A side, where 3 is a wireless device,
Reference numeral 30 denotes a primary radiator, 4 denotes an antenna, and Ca denotes a camera, which are the same as those shown in FIGS.
The wireless device 3 includes a high-frequency amplifier 31, a local oscillator 32, and a high-frequency signal output from the high-frequency amplifier 31 and the local oscillator 3.
2, an intermediate frequency generator 34, an intermediate frequency amplifier 34, a demodulator 3,
5. The intermediate frequency amplifier 34 detects the level of the received signal.
Gain control signal (AGC) for automatically controlling the amplification of
), And a transmission circuit 37. The signal from the demodulator 35 is transmitted to the control device 8 of the work machine A. The receiving circuit and the transmitting circuit 37 are the same as the receiving circuit and the transmitting circuit of a normal radio.

Reference numeral 5 denotes a camera platform that supports the wireless device 3. 51
Denotes a fixed base, which is fixed to an appropriate part of the work machine A, for example, an upper part of a cab. 52 is a motor fixed to the fixed base 51, 53 is an encoder for detecting the rotational position of the motor 52, and 54 is a swivel base rotatably supported by the fixed base 51 and rotated in the direction of the arrow θ ₅₄ by the motor 52. is there. Reference numeral 55 denotes a frame fixed to the case of the wireless device 3, which is rotatably supported by the swivel table 54. Reference numeral 57 denotes a motor, which moves the frame 55 with respect to the turntable 54 by an arrow θ.
Rotate in the direction of ₅₅ . 58 is an encoder for detecting the rotational position of the motor 57. The encoders 53 and 58 have a function of outputting two pulses having a phase difference of 90 degrees.

Reference numeral 6 denotes a motor drive unit, which is a servo amplifier 61 for driving and controlling the motor 52 of the head 5, a servo amplifier 62 for driving and controlling the motor 57 of the head 5, and a servo for driving and controlling the motor 42 of the antenna 4. It is composed of an amplifier 63. These servo amplifiers 61, 62, and 63 receive the signals of the encoders 53, 58, and 44, respectively, and feedback-control the driving of the motors 52, 57, and 42, respectively. A speed setting device 63a including a power supply sets the speed of the motor 42 to a predetermined speed.

Reference numeral 7 denotes a main control unit. This main control unit 7
Counter 71 for inputting signal of encoder 44, AGC
A band pass filter (BPF) 72 for inputting a signal, A
It comprises a / D converter 73, a microcomputer 74, a D / A converter 75, and a D / A converter 76.

Although the transmitting / receiving device 1A shown in FIG. 1 is a transmitting / receiving device on the work machine A side, the transmitting / receiving device on the operating device B side has the same configuration, so that its illustration is omitted.
Of course, on the operation device B side, the device connected to the transmission circuit is a device that outputs a signal according to the operation of the operation lever,
The device connected to the demodulator is a monitor device.

Next, the operation of this embodiment will be described. The operation device B outputs an operation signal to the work machine A. This operation signal is radiated from the antenna 4 while being superimposed on the carrier frequency signal. As described above, since the sub-reflector 43 of the antenna 4 is rotating, the beam carrying the operation signal is a rotating beam as described above. The beam radiated from the antenna of the operating device B in this way is sequentially captured by the antenna 4 of the work machine A (the sub-reflector 43 is rotating), and is transmitted to the high-frequency amplifier 31 via the primary radiator 30. After that, the signal is input to the demodulator 35 by a known operation.
An operation signal included in the received signal is extracted by the demodulator 35 and transmitted to the control device 8. The control device 8 drives the work machine A based on the transmitted operation signal to perform work. The state of the working part of the working machine A is imaged by the camera Ca, and the image signal is superimposed on the carrier frequency signal by the transmission circuit 37, and the rotation of the antenna shown in FIG. Emitted as a beam.
This beam is captured by the antenna of the operating device B, received by the receiving circuit of the operating device B in exactly the same manner as described above, the image signal is extracted by the demodulator, and the transmitted image is displayed on the monitor. The operator of the operating device B drives the operating device while watching the image on the monitor, and outputs an operation signal to the work machine A.
Send to

Here, it is generally known that the reception gain and the transmission gain of the antenna coincide with each other, and rotating a transmission beam is the same as changing the reception sensitivity gain. That is, the receiving sensitivity changes with the rotation of the sub-reflector. In the present invention, the sub-reflector 43 is rotated, and the antenna is directed in the direction in which the received signal is large by using the intensity of the received radio wave to track the antenna.

Incidentally, such transmission and reception of signals cannot be performed unless the antenna on the working machine A and the antenna on the operating device B are facing each other. That is, even if the work machine A moves, turns, or moves up and down during the work, the antenna on the operation device B side is the antenna on the work machine A side, and the antenna on the work machine A side is the operation device B side. Antennas must track each other. Such bidirectional tracking operation is performed by the camera platform 5, its motor drive unit 6, and its main control unit 7.
This will be described with reference to FIG.

FIG. 5 is a diagram showing the deviation of the reception beam and the level of the reception signal at that time. In this case, it is assumed that the sub-reflector of the antenna on the operation device B side is fixed. On the left side of (a) to (d) of FIG.
The level of the received signal is shown on the right side. In the figure,
S ₀ is the central axis of the parabolic antenna on the work machine A side, S _R
Is the trajectory (circle) of the beam transmitted from the operating device B side. FIG. 5A shows a state in which the center axis S ₀ coincides with the center of the trajectory S _R , that is, a state in which the antenna 4 on the working machine A side and the antenna on the operating device B side face exactly. In this case, the level of the received signal at each position on the circumference of the sub-reflector 43 is constant. In this embodiment, since the AGC signal output from the level detection circuit 36 of the wireless device 3 is a signal proportional to the received signal level, the AGC signal is used as the received signal level.

FIG. 5B shows a state in which the central axis S ₀ is shifted from the center of the trajectory of the transmission beam toward the angular position 0 °, and in this case, the received signal level is the angular position 0 °. (360 degrees) and the smallest at an angular position of 180 degrees. In FIG. 5C, the central axis S ₀ is the same as that of FIG.
On the contrary, from the center of the trajectory of the transmission beam,
It is a figure showing the state where it shifted to the degree, and in this case, the received signal level is the smallest at the angle position of 0 degree (360 degrees), and becomes the largest at the angle position of 180 degrees. Further, FIG.
(D) is a diagram showing a state in which the central axis S ₀ is shifted from the center of the trajectory of the transmission beam toward the angular position 0 ° and upward, and in this case, the reception signal level is on the right side thereof. It becomes like the curve shown.

Thus, by looking at the received signal level, it is possible to determine how the antenna 4 is deviated from the beam coming from the operating device B,
The motors 52 and 57 of the camera platform 5 are driven in a direction to correct the displacement, and the antenna on the operation device B side can be tracked. On the operation device B side, in the same manner as above,
The antenna 4 on the work machine A side can be tracked. The main controller 7 determines the direction of the displacement of the antenna, and the motor driver 6 operates to drive the motors 52 and 57 of the camera platform 5 according to the command of the result of the determination.

In order to perform such tracking, the main controller 7
Input the output signal of the encoder 44 to the counter 71 to obtain the current angular position of the sub-reflector 43,
Of the AGC signal output from the level detection circuit 36 of FIG. Here, the function of the band-pass filter 72 will be described with reference to FIG.

FIG. 6 is a diagram showing the displacement of the reception beam and the level of the reception signal at that time, similarly to FIG. Now, temporarily,
Assuming that the sub-reflectors of both antennas are rotating at the same rotation speed, if one of the antennas is shifted as shown in FIG. 6A, the received signal level is shown on the right due to the rotation of that antenna. The received signal level changes as shown on the right side of FIG. 6B due to the rotation of the other antenna (having the same displacement). Therefore, the actual change of the AGC signal is a change in which both are superimposed as shown in FIG. 6 (c). As a result, a plurality of maximum values and a plurality of minimum values respectively appear during one rotation, and the tracking of the antenna of the other party is performed. Will not be able to. Thus, if the rotation speeds of the sub-reflectors of both antennas are the same, bidirectional antenna tracking becomes impossible. Therefore, in the present embodiment, both rotation speeds are set to different rotation speeds, and only the frequency component that matches the own rotation speed is extracted from the AGC signal to remove the influence of the frequency component of the other party's rotation speed. Tracking becomes possible. The band-pass filter 72 of the main controller 7 shown in FIG. 1 is provided for this purpose.

As for the rotation speed of the sub-reflector, a quick response is necessary because the work machine A has more vibrating and moving, and from this viewpoint, it is better to increase the rotation speed of the work machine A. preferable. However, tracking is possible even if the rotation speed of the operation device B is faster.

The band-pass filter 72 receives the input A
Only the signal of the frequency component that matches the rotation speed of the sub-reflector 43 is extracted and output from the GC signal. This signal is A /
The data is converted into a digital value by the D converter 73 and input to the microcomputer 74. The microcomputer 74 performs a predetermined process based on the input AGC signal and the rotation angle position of the sub-reflector 43 obtained from the counter 71, so as to track the antenna on the operation device B side. It calculates how to drive the motor 52 of the revolving base 54 and the motor 57 for raising and lowering (tilting vertically) the wireless device 3, and outputs the calculation result to each of the servo amplifiers 61 and 62. An example of the processing of the microcomputer 74 will be described with reference to the flowchart shown in FIG.

In this processing example, an interrupt processing for reading the A / D conversion value of the AGC signal for each rotation pulse of the drive motor of the sub-reflector, a processing for determining the entire tracking direction based on a reference position signal once per rotation, and It is an example divided into. In both processes, an interrupt process is performed based on the encoder pulse of the motor. The priority level of the interrupt is set higher for the rotation pulse. The rotation pulse of the sub-reflector is 1
It is assumed that 360 pulses are set per rotation, and that the reference pulse is set to be generated when the beam shown in FIG.

FIG. 7A shows the flow of processing when a rotation pulse is generated. In this process, first, an AGC signal is fetched (procedure S1), and then a process of storing the fetched AGC signal in a predetermined storage area is performed (procedure S2). The processes in steps S1 and S2 are repeated a number of times corresponding to one rotation of the drive motor, that is, 360 pulses (steps S3 and S4).

On the other hand, when a reference pulse is generated, the processing shown in FIG. That is, FIG.
In the example of (b), in order to divide one rotation into a horizontal component and a vertical component, a total sum of AGC signals is obtained every 90 degrees (steps S10 to S13). That is, 0-89 degrees, 90-179
, 180-269 degrees, and 270-359 degrees, and sums E1, E2, E
3, E4 is now required.

Then, in order to obtain the vertical component, the procedure S
10, the sum of E1 and E2 obtained in S11,
The sum of E3 and E4 obtained in S13 is compared (procedure S1
4). If E1 + E2 is greater than E3 + E4,
The reception intensity means that the upward direction is large, and transmits an upward angle command signal Ev to the camera platform (step S16).

Similarly, in order to obtain the horizontal component, the procedure S
11, the sum of E2 and E3 obtained in S12,
Compare the sum of E1 and E4 obtained in S13 (procedure S1
5). If E1 + E4 is greater than E2 + E3,
It means that the reception intensity is higher in the right direction, and the right angle command signal Eh is transmitted to the camera platform (step S1).
6).

The vertical and horizontal angle command signals Ev and Eh are transmitted to the D / A converters 75 and 76, and the vertical and horizontal drive motors operate according to the converted values. Thereby, the antenna tracks in the direction of the other party.

Here, the experimental results are shown in FIG. In this figure, the horizontal axis represents time (seconds) and the vertical axis represents voltage (V). FIG. 8A shows an AGC signal in a state where both antennas face each other, and the AGC signal is constant at about 4.5 V. FIG. 8B is a diagram showing an AGC signal in a state in which one antenna is tilted upward by 7.2 degrees with respect to the other antenna, and T is one of the sub-reflectors.
Indicates the period of rotation. In this case, the AGC signal changes periodically, and a voltage level around 3 V exists during the period T.

As described above, in this embodiment, the sub-reflectors of the work machine and the operating device are decentered and rotated at different speeds, and the AGC signal of the receiving circuit and the sub-reflector are Is calculated based on the angular position of the other party, so that both the operating device side and the work machine side antennas can be turned,
Despite continuous changes in movement, vibration, etc., they can track each other, and image signals of the work site are sent from the work machine to the operation device, and operation signals are sent from the operation device to the work machine. The transmission can be performed without a relay station.

In the embodiment shown in FIG. 1, the AGC signal is input to the band-pass filter 72 and the output thereof is output to the A / D converter 7.
Means for converting into a digital value at 3 is adopted. By the way, many noises are generated during the operation of the work machine, and S
The / N ratio deteriorates, and it is often difficult to extract the AGC signal as a clear signal as shown in FIG. In order to cope with this, an A / D converter of a one-chip microcomputer is used instead of the band-pass filter 72 and the A / D converter 73, and a sub-reflector 43 in the AGC signal is provided by a digital filter configured therein. It is sufficient to take out only the signal of the frequency component that matches the rotation speed of.

FIG. 9 is a diagram showing the digital filter. In this figure, a ₀ is an A / D converter for inputting an AGC signal and converting it into a digital value, d ₁ , d ₂ ,...
... D _n indicate n delay units, and each delay unit is an antenna 4
Has a delay time corresponding to a half cycle of the motor 42. a
₁ , a ₂ ,..., _An are operation units, and when each input signal is of an odd-numbered delay unit, the operation unit performs subtraction and is of an even-numbered delay unit. In this case, addition is performed. The delay time is controlled by an internal counter of a one-chip microcomputer, and the calculation is performed by the calculation function of the microcomputer. The rotation speed of the sub-reflector 43 is 30
00 rpm, which is 50 when converted to frequency.
Hz, which is sufficient for a general-purpose microcomputer.

It should be noted that the half-cycle digital filter is a filter having a normal one-cycle delay time.
Although the double frequency component cannot be removed, it can be removed if it has a half-cycle delay time. Therefore, as described above, the rotational speed of the sub-reflector on the work machine A side and When making the rotation speed of the sub-reflector on the operation device B side different, for example, 1500 rpm and 3000 rpm
This is because a double relationship can be provided as in the above, and the degree of freedom in design can be increased.

By using such a digital filter, it is possible to extract a weak signal equivalent to the noise mixed therein. Particularly, when the working machine and the operating device are at a long distance and the arriving radio wave is weak. It is valid.

In the above embodiment, an example in which an image signal is transmitted from the work machine has been described. However, various signals other than the image signal, for example, a failure signal can be transmitted. Further, the present invention can be applied without any trouble even if not only the working machine but also the operating device is simultaneously moving.

[0041]

As described above, according to the present invention, the sub-reflectors of the work machine side and the operation device side antennas are decentered and rotated at mutually different speeds. Since the deviation from the antenna of the other party is calculated based on the angular position, the antennas on both the operating device side and the work machine side can be used despite the continuous change of turning, movement, vibration, etc. of the work machine. It is possible to track each other, and it is possible to reliably transmit an image signal of a work site from the work machine to the operation device and an operation signal from the operation device to the work machine without a relay station.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission / reception device including an antenna tracking device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a work machine and its operation device.

FIG. 3 is a diagram showing antennas provided in the transmitting and receiving apparatuses 1A and 1B shown in FIG. 2;

FIG. 4 is a diagram illustrating a rotating beam.

FIG. 5 is a diagram illustrating a shift of a reception beam and a level of a reception signal at that time.

FIG. 6 is a diagram for explaining the reason why the rotational speeds of both rotating beams are different.

FIG. 7 is a flowchart illustrating an operation of the microcomputer illustrated in FIG. 1;

FIG. 8 is a view showing an experimental result.

FIG. 9 is a diagram showing a digital filter.

[Explanation of symbols]

 Reference Signs List 3 radio 4 antenna 5 pan head 6 motor drive unit 7 main control unit 36 level detection circuit 52, 57 motor 53, 58 encoder 71, 72, 73 counter 72 band-pass filter 74 microcomputer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshinori Eguchi 650, Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory

Claims (6)

[Claims] An apparatus for transmitting and receiving a radio signal between a work machine and an operation device located at a remote location from the work machine to operate the work machine with the operation device, wherein the operation device side and the work An antenna for transmitting and receiving radio waves, a radio for transmitting and receiving via the antenna, a beam rotating unit for rotating a transmitting and receiving beam transmitted and received by the antenna, and a rotational position of the beam rotating unit are detected on each of the machine sides. Rotational position detecting means, a receiving level detecting means for detecting a level of a signal received by the wireless device, a rotational position detected by the rotational position detecting means, and a rotational position detected by the receiving level detecting means at that time. A control unit for controlling the antenna so as to face the antenna of the other party based on the reception level. 2. The antenna tracking device according to claim 1, wherein the rotation speed of the rotation unit is different between the operation device side and the work machine side. 2. The antenna tracking device according to claim 1, wherein the rotation speed of the beam rotation means is higher on the work machine side than on the operation device side. 3. The filter according to claim 1, wherein the control unit extracts only a signal of a rotation frequency component of the beam rotation unit from the reception level signal detected by the reception level detection unit and supplies the signal to the control unit. An antenna tracking device comprising: 4. The antenna tracking device according to claim 3, wherein the filter is an analog filter. 5. The antenna tracking device according to claim 3, wherein the filter is a digital filter. 6. The antenna tracking device according to claim 3, wherein the digital filter extracts an average value of at least four periods.