JPS63271182A - Automatic controller for antenna beam direction - Google Patents

Abstract

PURPOSE:To automatically estimate and correct an error contained in an observation value of a position measuring instrument, an oscillation detector, and an azimuth detector, by constituting a composite tracking system of a program tracking system and a conical scan system. CONSTITUTION:An error correcting part 13 receives each observation value of a roll angle, a pitch angle and a nose azimuth of a moving body and the present position, and an error estimated value from an error estimating part 12, and forms each estimated value of the roll angle, the pitch angle, the nose azimuth and the present position. A program tracking control part 9 executes a predicting calculation of a radio wave incoming direction, and this output is added to an output of a conical scan signal generating part 10 by an adding part 17. An oscillation correcting part 8 outputs a controlled variable to an antenna driving mechanism. An error estimating part 12 derives an error estimated value to each observation value of the roll angle, the nose azimuth and the present position of the moving body, based on a directional error observation value from a directional error detecting part 11. A correction of the error and a program tracking control are executed by an observation value whose error has been corrected.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to an automatic antenna beam direction for directing the beam direction of an antenna mounted on a moving object such as an aircraft, vehicle, or ship toward a radio wave generation source. Regarding a control device.

(Prior Art) As is well known, in a satellite communication system, a satellite emits beacon radio waves in order to always point an antenna toward the satellite.

That is, satellites are the source of radio waves, but other sources of radio waves include, for example, bases in submarine oil fields. Since bases for offshore oil fields are set on the ocean, personnel are transported by ship or helicopter, but there are cases where beacon radio waves are emitted from the bases in case of rough weather.

Furthermore, as is well known, as methods for automatically tracking the direction of arrival of radio waves, there are known a self-tracking method and a program tracking method. The self-tracking method is based on feedback control, and is a method of receiving beacon radio waves and automatically driving the antenna in the direction of arrival. There are various methods for this, such as a conical scan method, a step track method, and a monopulse method. The program tracking method is based on so-called open-loop control, and is a method in which the direction of arrival of radio waves is determined by predictive calculation, and the antenna is directed in the predicted direction.

(Problems to be Solved by the Invention) By the way, when configuring an automatic antenna beam direction control device that controls an antenna mounted on a moving object,
It is natural that tracking accuracy is an issue, but it is also necessary to adopt a tracking method that does not complicate the structure of the antenna and its drive mechanism (referred to as a gimbal mechanism) and allows for overall miniaturization.

First, let's consider from the perspective of tracking accuracy. The step track method moves the antenna direction step by minute at regular time intervals, determines whether the received level has increased or decreased by taking an appropriate integration time, and if it has increased, the antenna is moved further in the same direction, and if it has decreased, it is moved in the same direction. Since the method determines the maximum point of reception level by moving in the opposite direction, it is not suitable for moving objects that make arbitrary movements such as turning or meandering. In addition, in the program tracking method, when the mobile object is, for example, a mobile communication terminal station in a satellite communication system, the current position of the satellite is calculated in a fixed coordinate system determined from the orbital elements of the known satellite, and The azimuth and elevation angles to which the antenna should point in the horizontal plane at that point are predicted and calculated from the observed value of the own position at that point.

This predicted value is corrected based on the heading angle and swing angle (roll angle and pitch angle) of the mobile object, and the control amount for the antenna drive mechanism is calculated based on the corrected predicted value. The antenna is driven and controlled to maintain the pointing direction of the antenna beam in the target direction. This method has the advantage of easy control. However, errors in the positioning device that measures the current position of the moving object, the azimuth detector that measures the yaw angle of the moving object, and the oscillation detector that detects the roll and pitch angles result in pointing errors in the antenna beam direction. appears. In satellite communications, if the pointing error exceeds a permissible value (1/2 of the beam width), both reception level and transmission efficiency will drop, making communication impossible. Mobile communication terminal stations use highly directional antennas, so in order to control the antenna direction using only the program tracking method, highly accurate positioning equipment, direction detectors, and motion detectors are required. There is a problem.

On the other hand, both the conical scan method and the monopulse method detect the difference between the antenna beam direction and the actual direction of the target from the received signal of the beacon radio wave, that is, the antenna pointing error signal. Since it is feedback control that drives the antenna, it has the advantage that highly accurate tracking can be expected even for moving objects that move arbitrarily.

Next, consideration will be given to whether the structure of the antenna and its drive mechanism can be simplified.

The monopulse method requires multiple horns and corresponding waveguides, and it can be said that it is basically impossible to simplify the structure. Furthermore, since the conical scan method rotates the antenna beam conically, the antenna is driven frequently.

Therefore, in this method, durability must be taken into consideration, and the antenna drive mechanism becomes complicated.

On the other hand, in the program tracking method, the frequency of driving the antenna is much lower than in the conical scan method, so there is an advantage that the antenna driving mechanism can be simplified.

The present invention was made in view of the necessity of controlling the beam direction of an antenna mounted on a moving body, and its purpose is to configure a composite tracking method that mainly uses a program tracking method and a conical scan tracking method as a secondary method. Therefore, it is an object of the present invention to provide an automatic antenna beam direction control device that takes advantage of the advantages of both systems and eliminates their drawbacks.

(Means for Solving the Problems) In order to achieve the above object, an automatic antenna beam direction control device of the present invention has the following configuration.

That is, the automatic antenna beam direction control device of the present invention has the following features:
A device for directing the beam direction of an antenna mounted on a mobile object toward a radio wave generation source, the device comprising: a device for directing a beam direction of an antenna mounted on a mobile object in the direction of a radio wave generation source; and an error correction unit that forms estimated values of a roll angle, a pitch angle, a heading, and a current position. a program tracking control unit that predicts and calculates; a conical scan signal generation unit that can generate at any timing a conical scan signal for rotating the beam direction of the antenna at a predetermined offset angle around the conical scan center axis; an adding section that adds the output of the tracking control section and the output of the conical scan signal generating section; receiving the output of the adding section and the estimated values of the roll angle, pitch angle, and heading, and adds the output to the antenna drive mechanism; It calculates and outputs the control amount, and it directs the antenna beam in a predetermined direction by adding correction operations based on each estimated value to the predicted direction determined by the program tracking control unit, and also directs the antenna beam in a conical direction. a sway correction unit that rotates the antenna beam as a scanning center axis; and a vibration correction unit that rotates the antenna beam as a scanning center axis; receives a transmission signal from a radio wave source received by an antenna that rotates the beam direction in a conical shape, and calculates a predicted direction of the target and an actual direction of the target. A pointing error detection unit that observes and obtains pointing errors between the bow and the pointing error; and an error estimation for each observed value of the roll angle, pitch angle, heading, and current position of the moving object based on the observed pointing error values output by the pointing error detection unit. The present invention is characterized by comprising: an error estimating section that calculates a value and sends it to the error correcting section;

(Function) Next, the function of the automatic antenna beam direction control device of the present invention configured as described above will be explained.

The error correction section adjusts the roll angle and pitch angle of the moving object.

Receiving the observed values of the heading and current position and the estimated error values, each estimated value of the roll angle, pitch angle 9 heading and current position is formed.

The program tracking control unit predicts and calculates the radio wave arrival direction from the known or calculated position of the radio wave source and the estimated current position.

That is, when a radio wave source is located at a fixed point on the earth, such as an offshore oil field base, its location data (latitude, etc.) is transmitted.

For example, in the case of a geostationary satellite, the position (latitude, longitude) is calculated from its orbit data.

On the other hand, the conical scan signal generation section is configured to generate a conical scan signal at an arbitrary timing, that is, when necessary, to rotate the beam direction of the antenna at a predetermined offset angle around the conical scan center axis. .

The addition section adds the output of the program tracking control section and the output of the conical scan signal generation section.

The sway correction section receives the output of the addition section and the estimated values of the roll angle, pitch angle, and heading, and calculates and outputs a control amount for the antenna drive mechanism, and the program tracking control section calculates and outputs a control amount for the antenna drive mechanism. A correction operation based on each estimated value is applied to the obtained predicted direction to direct the antenna beam in a predetermined direction, and the antenna beam is rotated using the directed direction as the center axis of the conical scan.

The pointing error detection unit receives the transmission signal from the radio wave source received by the antenna whose beam direction is rotated in a conical shape, observes and obtains the pointing error in the predicted direction of the target and the actual direction of the target, and then estimates the error. The unit calculates error estimates for each of the observed values of the roll angle, 81 head direction, and current position of the moving body based on the observed pointing error values output by the pointing error detection unit,
It is sent to the error correction section.

In this way, correction of errors included in each observed value of the moving object and program tracking control are performed using the error-corrected observed values, the pointing error is reduced, and pointing accuracy is improved by program tracking control and conical scanning. This will be improved by combining it with other methods.

As described above, according to the automatic antenna beam direction control device of the present invention, since the tracking method is a combination of the program tracking method and the conical scan method, the observed values of the positioning device, the vibration detector, and the direction detector include Since errors are automatically estimated and corrected, the performance requirements for these devices can be relaxed and the drawbacks of program tracking methods can be overcome.

It also has an error estimation and correction function, so it estimates the error by compounding for a certain period, stops compounding for other periods, and
Correction can be continued using the error estimation value obtained during the compounding period, and high precision tracking can be continued without interruption.

As a result, in the case of a conical scan in which the horn of a normal antenna reflector is mechanically rotated, the frequency of rotation can be reduced. This, together with the fact that the period of conical scanning can be lengthened, makes it possible to simplify the structure of the antenna and its drive mechanism, and to extend its life. That is, the drawbacks of the conical scan method can be overcome.

Furthermore, even if the acquisition of pointing error data based on the conical scan method is interrupted due to radio wave interference or the like, program tracking makes it possible to continue operation, thereby providing various excellent effects such as increased reliability.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an automatic antenna beam direction control device according to an embodiment of the present invention. This antenna beam direction automatic control device is used in a mobile communication terminal station in a satellite communication system. , a transceiver 2, an antenna drive mechanism (gimbal mechanism 3, drive motor 4, servo amplifier 5, compensation circuit 6, and rotation angle detection section 7), an oscillation correction section 8, a program tracking control section 9,
Conical scan signal generation section 10 and pointing error detection section 1
1, an error estimation section 12, an error correction section 13, an agitation detector 14, a positioning device W16, and an addition section 17.

The oscillation detector 14 detects the roll angle and pitch angle of the moving body and supplies them to the error corrector 13.

The azimuth detector 15 detects the yaw angle of the moving body and supplies it to the error corrector 13. In addition, the positioning device measures the current position of the moving object and its observed value (latitude).

longitude) is supplied to the error correction unit 13.

During normal operation, the error correction unit 13 is based on the error estimate supplied from the error estimation unit 12, and when the supply of error estimate from the error estimation unit 12 is interrupted, it is based on the immediately previous error estimate. Based on the oscillation detector 14. Direction detector 1
5 and the positioning device 16 (details will be described later), the estimated value λ of the latitude measured value λ and the estimated value of the longitude observed value are sent to the program tracking control unit 9, and the azimuth observed value The estimated value of ψ, the estimated value of the observed roll angle value φ; and the estimated value δ of the observed pitch angle value θ are supplied to the sway correction unit 8, respectively.

The program tracking control unit 9 is given satellite orbit data (in the case of a geostationary satellite, it consists of latitude, longitude, and altitude data), and combines this orbit data with an estimated self-position 9, that is, an estimated latitude or Based on the estimated longitude value C, the expected direction of the satellite as seen from its own position is calculated.

The expected direction is calculated as the expected azimuth Az from the true north and the expected elevation angle Et from the horizontal plane in a horizontal coordinate system whose coordinate axes are three orthogonal axes: true north, east, and zenith. This predicted direction signal is supplied to one input of the adder 17.

The adder 17 has the other input supplied with the conical scan signal from the conical scan signal generator 10 , and the conical scan signal and the predicted direction signal are added together and output to the sway corrector 8 .

However, since the conical scan signal is generated at an arbitrary timing as described later, the adding section 17 and the oscillation correcting section 8
Most of what is output to is only the expected direction signal.

Therefore, the processing of this expected direction signal will be explained first.

In consideration of the fact that the moving body has moment-to-moment fluctuations in the yaw angle, roll angle, and pitch angle, the sway correction unit 8 converts the expected azimuth A2 and the expected elevation angle El into the estimated azimuth value @, the estimated roll angle value φ, and In addition to correcting the estimated pitch angle value δ, a gimbal axis angle control amount is calculated by taking into account the degree of freedom of the gimbal mechanism 3 and structural factors, and is supplied to the compensation circuit 6.

Note that the gimbal mechanism 3 may be a 2-axis system, a 3-axis system, or
Various methods such as a 4-axis method are applicable.

The compensation circuit 6 measures the error between this gimbal axis angle control amount and the gimbal axis actual angle detected and output by the rotation angle detector 7 attached to each axis of the gimbal, and adds the gimbal axis angle control amount to the gimbal axis actual angle. Compensation processing necessary to follow the angle is performed, and the static characteristics, dynamic characteristics, and stability of the servo loop are improved.

The output of the compensation circuit 6 is amplified by the servo amplifier 5, and the shaft rotation angle of the gimbal mechanism 3 is changed by the drive motor 4. Changes in the shaft rotation angle are detected by the rotation angle detector 7 and fed back to the compensation circuit 6. the result,
The gimbal axis actual angle follows the gimbal axis angle control amount, and the beam direction of the antenna reflector 1 on the gimbal axis is directed toward the satellite.

Incidentally, normally, the observed values of roll angle φ, pitch angle θ, azimuth angle ψ, latitude λ, and longitude obtained from the oscillation detector 14, the azimuth detector 15, and the positioning device 16 include errors. Due to this error, the pointing direction of the central axis of the antenna beam does not match the actual direction of the satellite, resulting in a pointing error ε, which impedes communication with the satellite.

Therefore, the conical scan signal generating section 10 is given an activation command (not shown) at an appropriate timing during the program tracking process as described above, and generates a conical scan signal with a conical scan period ωS and an offset angle β. This conical scan signal is added to the expected direction Az of the expected direction signal output by the program tracking control section 9 in the adder 17.
, and the expected elevation angle Et, and input to the sway correction section 8.

The oscillation correction section 8 calculates the gimbal axis angle control amount as described above and supplies it to the compensation circuit 6. the result,
The central axis of the antenna beam of the antenna reflector 1 has the direction determined by the expected azimuth Az and the expected elevation angle Et as the conical scan central axis, and rotates conically at a period ωS with an offset angle β. And transmitter/receiver 2
The received signal obtained in the above is demodulated by a conical scan signal in the pointing error detection section 11, and the observed value of the pointing error is obtained every moment. The observed value of the pointing error consists of an error δAZ with respect to the expected azimuth Az and an error δEt with respect to the expected elevation angle Et, and these are supplied to the error estimator 12.

The error estimation unit 12 inputs a series of observed values (δAX,
δEt) based oscillation detector 14. Errors δφ and δθ included in the observed values of the direction detector 15 and the positioning device 16,
Kalman Filt the same δψ, the same δλ and the same δL
er method or Maximum Likelih-ood
Estimation is performed using the Estimation method or the like, and each of the obtained error estimation values is supplied to the error correction unit 13.

Note that the error δAz, the same δEt, and the error δφ, the same δθ.

The relationship between δψ, δλ, and δL is nonlinear, but if Taylor expansion is performed around the true value and high-order terms are omitted, it is given by the following equations (1) and (2).

δAz=f, δφ+f2δθ+f, δψ+f4δλ+f
, δ ----<i> δEL = g1 δφ + g2 δθ + g3 δψ ten g4 δλ ten g
5δL−−−−−−(2> Here, the function f; (i=1 to 5), the same g + (x =
1 to 5) are functions of roll angle φ, pitch angle θ, azimuth ψ, latitude λ, and longitude.

In the error correction unit 13, the oscillation detector 14. Direction detector 15
Then, the estimated error value is subtracted from each observation value of the positioning device 16, and the estimated roll angle φ, estimated pitch angle θ, and estimated azimuth value ↓ are sent to the sway correction unit 8 as the estimated latitude value or the estimated longitude value. The value C is supplied to the program tracking control section 9, respectively.

Therefore, in this error correction unit 13, since there is no estimated error value before tracking is performed using the conical scan method, in this case, the oscillation detector 14 and the direction detector 15
The observed value is directly sent to the sway correction unit 8, and also to the positioning device 16.
The observed values are respectively supplied to the program tracking control section 9 as they are.

After tracking is performed using the conical scan method, the operation described above is performed based on the latest error estimated value when there is input, and the one immediately before the input when error estimated value is interrupted. I do.

In this way, under normal operating conditions in which tracking based on the conical scan method is performed at appropriate timings during tracking based on the program tracking method, oscillation correction and program tracking control are performed based on error-corrected observations. As a result, the pointing error decreases and converges until the average value of the pointing errors δAZ and δEl becomes zero. In other words,
An error estimation value such that the average value of pointing errors becomes zero is obtained, and pointing accuracy is improved by combining program tracking control and the conical scan method. Furthermore, even if the observed value of the pointing error by the conical scan method is discontinued for some reason and cannot be obtained, the composite state continues by correcting the observed value using the previous error estimate.

(Effects of the Invention) As described in detail above, according to the automatic antenna beam direction control device of the present invention, the combined tracking method of the program tracking method and the conical scan method is used. Since the errors included in the observed values of the detector are automatically estimated and corrected, the performance requirements for these devices can be relaxed and the drawbacks of the program tracking method can be overcome.

It also has an error estimation and correction function, so it estimates the error by compounding for a certain period, stops compounding for other periods, and
Correction can be continued using the error estimation value obtained during the compounding period, and high precision tracking can be continued without interruption.

As a result, in the case of a conical scan in which the horn of a normal antenna reflector is mechanically rotated, the frequency of rotation can be reduced. This, together with the fact that the period of conical scanning can be lengthened, makes it possible to simplify the structure of the antenna and its drive mechanism, and to extend its life. That is, the drawbacks of the conical scan method can be overcome.

Furthermore, even if the acquisition of pointing error data based on the conical scan method is interrupted due to radio wave interference or the like, program tracking makes it possible to continue operation, thereby providing various excellent effects such as increased reliability.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram of an automatic antenna beam direction control device according to an embodiment of the present invention. 1...Antenna reflector, 2...
Transmitter/receiver, 3...Gimbal mechanism, 4...
... Drive motor, 5... Servo amplifier, 6.
... Compensation circuit, 7 ... Rotation angle detection section,
8... Shake correction unit, 9... Program tracking control unit, 10... Conical scan signal generation unit, 11... Pointing error detection unit, 12.
...Error estimating unit, 13...Error correction unit, 14...Sway detector, 15...
Direction detector, 16...Positioning device, 17...
... Addition section.

Claims (1)

[Claims] A device for directing the beam direction of an antenna mounted on a mobile object toward a radio wave generation source; the device includes observation values of a roll angle, a pitch angle, a heading, and a current position of a mobile object, and an estimated error value. and an error correction unit that forms estimated values of the roll angle, pitch angle, heading, and current position based on the information; and a radio wave arrival direction based on the known or calculated radio wave source position and the current position estimate. a program tracking control unit that predicts and calculates; a conical scan signal generation unit that can generate a conical scan signal at an arbitrary timing for rotating the beam direction of the antenna at a predetermined offset angle around the conical scan center axis; and the program. an adding unit that adds the output of the tracking control unit and the output of the conical scan signal generating unit; an adding unit that receives the output of the adding unit and the estimated values of the roll angle, pitch angle, and heading, and adds the output to the antenna drive mechanism; It calculates and outputs the control amount, and it directs the antenna beam in a predetermined direction by adding correction operations based on each estimated value to the predicted direction determined by the program tracking control unit, and also directs the antenna beam in a conical direction. an oscillation correction unit that rotates the antenna beam as a scanning center axis; and a vibration correction unit that rotates the antenna beam as a scanning center axis; receives a transmission signal from a radio wave source received by an antenna that rotates the beam direction in a conical shape, and calculates a predicted direction of the target and an actual direction of the target. a pointing error detection unit that observes and obtains a pointing error with respect to the pointing error; and an error estimation for each observed value of the roll angle, pitch angle, heading, and current position of the moving object based on the observed pointing error value outputted by the pointing error detection unit; An apparatus for automatically controlling an antenna beam direction, comprising: an error estimating section that calculates a value and sends it to the error correcting section.