JP3232378B2 - Antenna pointing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna pointing device for pointing an antenna suitable for use in maritime satellite communication or the like toward a satellite.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional antenna pointing device. Such an antenna pointing device is basically called an azimuth-elevation system, and includes a base 3, an azimuth gimbal 40 mounted on the base 3, and a mounting mounted on a U-shaped member at the upper end of the azimuth gimbal 40. It has a metal fitting 41 and the antenna 14 attached to the mounting metal 41.

[0003] The base 3 may have a bridge portion 3-1.
The bridge portion 3-1 has a cylindrical portion 1 protruding upward.
0 ′ is mounted, and a pair of bearings 9-1 and 9-1 ′ are mounted inside the cylindrical portion 10 ′. An azimuth axis 10 is fitted to the inner rings of the bearings 9-1 and 9-1 ', and an azimuth gimbal 40 is mounted on the upper end of the azimuth axis 10 via an arm 10-1. Thus, the azimuth gimbal 40 has the azimuth axis (the azimuth axis 10 and the bearing 9-1,
9-1 ′ (center axis of 9-1 ′). The azimuth gimbal 40 has a lower support shaft portion 40-1 and an upper U-shaped portion 40-2, and is arranged such that the axis of the support shaft portion 40-1 is deviated from the azimuth axis.

A smaller U-shaped mounting bracket 41 is mounted on the U-shaped portion 40-2 of the azimuth gimbal 40.
The elevation axes 13, 1 between the two legs of the
It is rotatably supported around 3 '. Elevation axis 13,
13 'is arranged at right angles to the azimuth axis and is therefore in a substantially horizontal position. That is, the U-shaped part 4 of the azimuth gimbal 40
Each of the two legs 0-2 has an elevation shaft bearing 16, 1
6 ′ is mounted, and the mounting bracket 41 can rotate around the elevation axis 13, 13 ′ by such bearings 16, 16 ′.

The leg 41 of the U-shaped mounting bracket 41
1, 41-1 'is provided with an antenna 14, so that the antenna 14 is mounted together with the mounting bracket 41 on the elevation axis 1 line.
Rotate around 3, 13 '. Antenna 14 is center axis X
−X, and such central axes are elevation axes 13, 1
Perpendicular to 3 '.

The mounting bracket 41 includes an elevation gyro 44
, A direction gyro 45, a first accelerometer 46, and a second accelerometer 47. Antenna 14 rotated around elevation axes 13 and 13 'by elevation gyro 44
And the azimuth gyro 45 detects the rotation angle of the antenna 14 about an axis orthogonal to both the elevation axes 13 and 13 ′ and the central axis XX of the antenna 14, and the first accelerometer 46 The inclination angles of the antenna 14 around the elevation axes 13 and 13 ′ are detected, and the second accelerometer 47 detects the elevation axes 13 and 13 with respect to the horizontal plane.
An inclination angle of 3 'is detected.

The elevation gyro 44 and the azimuth gyro 45 are
For example, in addition to an integrating gyro such as a mechanical gyro and an optical gyro, an angular velocity detecting gyro such as a vibration gyro, a rate gyro, and an optical fiber gyro may be used.

An elevation gear 48 is mounted on one leg of the mounting bracket 41 coaxially with the elevation axes 13 and 13 '. A pinion 50 is meshed with the elevation gear 48, and the pinion 50 is connected to the azimuth gimbal 4.
It is attached to the rotation axis of an elevation servomotor 49 mounted on one leg of the U-shaped portion 40-2.

On the other hand, the azimuth gear 1 is
1, an azimuth servomotor 52 and an azimuth transmitter 53 are mounted on the bridge section 3-1 of the base 3.
A pinion (not shown) attached to the rotation axis of the azimuth servomotor 52 and the azimuth transmitter 53 is configured to mesh with the azimuth gear 11.

[0010] As shown, four servo loops are provided to control the antenna pointing device. The center axis X-X of the antenna 14 is a horizontal plane and contact angle of elevation theta _A of the antenna, the central axis X-X of the antenna 14 is the azimuth angle phi _A of the antenna meridian and angle on a horizontal plane.

In the first loop, the elevation gyro 44
Is fed back to the elevation servomotor 49 via the integrator 54 and the amplifier 55. As a result, even when the hull swings, the angular velocities of the antenna 14 around the elevation axes 13, 13 'are always kept at zero.

In a second loop, the first accelerometer 4
6 is reduced by a signal indicating, for example, a manually set satellite altitude angle θ _S after passing through an arc sine calculator 57, and further passed through an attenuator 56 and an integrator 54 and an amplifier. 55 is input. This loop is
The elevation theta _A of the antenna 14 has a time constant to match the satellite altitude theta _S, elevation gyro 4 to the attenuator 56
In order to compensate for the drift fluctuation of No. 4, an integral characteristic is provided. The elevation control loop includes the first and second loops.

On the other hand, in a third loop, the 1 / cos θ calculation unit 76 calculates 1 / cos θ based on the elevation signal θ supplied from the elevation transmitter 72, and outputs the signal φcos θ of the azimuth gyro 45 to the calculation result. The multiplied value is fed back to the azimuth servomotor 52 via the integrator 58 and the amplifier 59, so that the antenna 14 is orthogonal to both the central axis XX and the elevation axes 13, 13 'of the antenna 14. Rotational motion of the hull around the axis can be stabilized, and the frequency characteristic of the azimuth control loop is constant regardless of the elevation angle θ of the antenna.

In a fourth loop, the azimuth gimbal 40
Is output from the azimuth transmitter 53, and the output signal φ is converted by the adder 61 into the satellite azimuth angle φ.
_The azimuth deviation signal is calculated based on _S and the azimuth angle φ _C supplied from, for example, a magnetic compass or a gyro compass, and is input to the integrator 58 via the subtractor 60. As a result, in that the azimuth angle phi _A of the antenna 14 (the sum of the rotation angle phi and heading angle phi _C azimuth gimbal 40) becomes equal to the satellite azimuth angle phi _S, the orientation of the antenna 14 is stationary.

This loop is composed of the azimuth angle φ _{A of the} antenna 14.
Has a time constant so as to coincide with the satellite azimuth φ _S , and the attenuator 60 has an integral characteristic to compensate for drift fluctuation of the azimuth gyro 45. That is, the outputs of the attenuators 56 and 60 correspond to the outputs of the integrating gyro torquer. The azimuth control loop is composed of the third and fourth loops.

In this manner, the antenna pointing device is controlled by two control loops including four servo loops so that the central axis XX of the antenna 14 is directed toward the satellite.

Here, the transfer function of the azimuth control loop will be considered. The gain of the amplifier 59 is -K, the proportional gain of the attenuator 60 is _KT , and the integral gain is _KT / TiS. For the sake of simplicity, the gain of the drive unit including the azimuth servomotor 52 and the azimuth gear 11 and the scale factor of the gyro are set to 1, and furthermore, the fluctuation of the hull is ignored. The transmission relationship of the rotation angle φ of the antenna after the Laplace transform is expressed by the following equations (1) and (2).

[0018]

(Equation 1)

(Equation 2)

Here, φ is the rotation angle of the antenna 14 around the azimuth axis, φ _S is the satellite azimuth angle, φ _C is the bow azimuth angle, θ is the rotation angle of the antenna 14 around the elevation angle axis, and U _z is the azimuth gyro. fixed errors, V _I is the output signal of the integrator 60-2, S is a Laplace operator. For example, φ _C = φ _C ′ / S, φ _S
= Φ _S ′ / S, U _z = U _Z / S Substituting into And the fixed error U _Z of the azimuth gyro is calculated by the integrator 60-2.
Azimuth angle of the antenna φ _A (= φ +
φ _C ) is equal to the given satellite azimuth φ _S.

[0020]

However, in such an antenna pointing device, the elevation angle of the satellite to be pointed varies depending on the latitude, and the inclination of the hull varies greatly due to shaking, so that the elevation angle θ of the antenna also varies. In Equation 1, since the fixed error U _Z of the azimuth gyro is multiplied by the coefficient 1 / cos θ, when the elevation angle θ of the antenna changes to θ ′, the integrator 60-2 cannot immediately follow. U _Z / K _T (1 / cos θ'-1 / cos
θ), which causes a transient angle error, resulting in a large pointing error with respect to the satellite.

In view of the foregoing, it is an object of the present invention to compensate for the fixed error of the azimuth gyro and to make the response of the system constant regardless of the value of the elevation angle θ.

[0022]

An antenna pointing device according to the present invention has an antenna 14 having a central axis and supported by a supporting member as shown in FIGS. 1 and 2, and the antenna 14 and the supporting member 41 are connected to the central axis. An azimuth gimbal 40 rotatably supporting an elevation axis orthogonal to XX; a base 3 rotatably supporting the azimuth gimbal 40 about an azimuth axis orthogonal to the elevation axis; A first gyro 44 having an input axis to be fixed to the support member 41 and a second gyro 45 having an input axis orthogonal to both the center axis and the elevation axis and fixed to the support member 41 And an accelerometer 46 for outputting a signal indicating the inclination angle of the central axis XX with respect to the horizontal plane, and outputting a signal indicating the rotation angle of the azimuth gimbal 40 around the azimuth axis. And a signal obtained by subtracting a value corresponding to the altitude angle of the satellite from the output signal of the accelerometer 46 is fed back to the substantial torquer of the gyro 44 via the attenuator 56 to transmit the azimuth signal. The azimuth deviation signal obtained by calculating the output signal of the azimuth unit 53 and the signals corresponding to the heading azimuth φ _C and the satellite azimuth φ _S by an adder 61 is converted into an attenuator 60.
To the substantial torquer of the second gyro 45 to direct the central axis XX of the antenna 14 toward the satellite, and furthermore, the elevation angle of the antenna 14 with respect to the azimuth gimbal 40. An elevation angle transmitter 72 that outputs a rotation angle signal indicating a rotation angle θ about an axis, and a 1 / cos θ calculation unit 7 that calculates a value of 1 / cos θ from the rotation angle signal output from the elevation angle transmitter 72.
6 and the output signal of the second gyro 45 is multiplied by the output signal of the 1 / cos θ arithmetic unit 76, and the multiplied value is input to the integrator 58, whereby the frequency characteristic of the servo system is completely reduced. In the antenna pointing device configured to be invariant at the elevation angle θ, a cos θ operation unit 60-3 for calculating the value of cos θ from the rotation angle signal output from the elevation transmitter 72 is provided. Is multiplied by the output signal of the cos θ operation unit 60-3,
This multiplication result is used as an integrator 60- for gyro drift compensation.
2 and outputs the output signal of the integrator 60-2 to this 1 /
This is configured to feed back to the input of the cos θ operation unit 76.

[0023]

According to the present invention, based on the elevation signal .theta. Supplied from the elevation transmitter 72, the cos .theta.
sθ is calculated, and the value obtained by multiplying the value of cos θ by the azimuth deviation signal is used as an integrator 60-2 for gyro drift compensation.
And the output signal of the integrator 60-2 is given by 1 / cos
Since it is configured to feed back to the input of the calculation unit 76 of θ, the output signal of the integrator 60-2 is a value that directly compensates the fixed bias of the azimuth gyro regardless of the value of the elevation angle θ. Therefore, no azimuth error occurs even if the elevation angle θ changes.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIGS. 1 and 2, corresponding parts in FIGS. 3 and 4 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

FIG. 1 shows an example of an antenna pointing device according to the present invention. The antenna pointing device includes a base 3, an azimuth gimbal 40 mounted on the base 3, and a U at the upper end of the azimuth gimbal 40. It has a mounting bracket 41 mounted on the letter-shaped member and the antenna 14 mounted on the mounting bracket 41.

The antenna 14 has a central axis XX, and an assembly comprising the antenna 14 and a mounting bracket 41 mounted on the antenna 14 is an elevation axis 13-13 orthogonal to the central axis XX. It is rotatably supported around '. The azimuth gimbal 40 is supported on a base so as to be rotatable about an azimuth axis 10 orthogonal to the elevation axis 13-13 '. In this manner, a support mechanism rotatable about two axes is formed, and the support mechanism is controlled so that the central axis XX of the antenna 14 is directed to the satellite.

The mounting bracket 41 includes an elevation gyro 44
, A direction gyro 45, a first accelerometer 46, and a second accelerometer 47. Antenna 14 rotated around elevation axes 13 and 13 'by elevation gyro 44
And the azimuth gyro 45 detects the rotation angle of the antenna 14 around an axis orthogonal to both the elevation axes 13 and 13 ′ and the central axis XX of the antenna 14, and the first accelerometer 46 The inclination angles of the antenna 14 around the elevation axes 13 and 13 ′ are detected, and the second accelerometer 47 detects the elevation axes 13 and 13 with respect to the horizontal plane.
An inclination angle of 3 'is detected.

The elevation gyro 44 and the azimuth gyro 45 may be either an integral gyro or an angular velocity detecting gyro.

According to the present embodiment, the elevation transmitter 72 is mounted on one leg of the U-shaped part 40-2 of the azimuth gimbal 40 coaxially or parallel to the elevation axes 13, 13 '. The elevation angle transmitter 72 has, for example, an elevation angle transmitter gear 74 that engages with the elevation angle gear 48, and the elevation angle axes 13, 1
The 3 ′ rotational displacement is configured to be detected via the elevation transmitter gear 74. The elevation angle transmitter 72 detects the rotation angle of the antenna 14 around the elevation axis 13, 13 ', that is, the elevation angle θ, and outputs a signal indicating the detected angle.

In the fourth loop, the azimuth gimbal 40
Is output from the azimuth transmitter 53, and the output signal φ is converted by the adder 61 into the satellite azimuth angle φ.
_An azimuth deviation signal is calculated by _S and the heading azimuth angle φ _C, and is input to the integrator 58 via the proportional unit 60-1 in the attenuator 60. On the other hand, based on the elevation signal θ supplied from the elevation transmitter 72, the cos θ operation unit 60-3 performs the cos θ calculation, and supplies the azimuth deviation signal multiplied by cos θ to the gyro drift compensation integrator 60-2. I do. This integrator output signal is calculated by the 1 / cos θ calculation unit 76
Of the bearing gyro 45 to compensate for the fixed error.

In the case of this example, the transfer function for the rotation angle φ of the antenna after the Laplace transform is calculated by the following equations 3 and 4 in the same manner as in the equations 1 and 2.

[0032]

(Equation 3)

(Equation 4)

Assuming that φ _C , φ _S , and U _Z are constant in the same manner as in Equations 1 and 2, the final value is obtained. From Equation 4, V _I = −U
_Z ′, and substituting this into Equation 3 gives The fixed error U _Z of the azimuth gyro is compensated by the integrator 60-2, and the azimuth angle φ _{A of the} antenna (= φ + φ _C )
Equal to the satellite azimuth angle phi _S which is given. Also, even if the elevation angle θ of the antenna changes due to the oscillation of the hull, 1 /
Since the value multiplied by cos θ is U _Z ′ −U _Z ′ = 0, no angular error occurs in the rotation angle φ, and as a result, the pointing accuracy with respect to the satellite is very good.

Here, the necessity of the cos θ operation unit 60-3 will be described. There is no cosθ operation unit 60-3,
Assuming that the azimuth deviation signal, which is the output signal of the adder 61, is directly supplied to the gyro drift compensation integrator 60-2,
The transfer function of the rotation angle φ is expressed by equation (5).

[0035]

(Equation 5)

The denominator (characteristic equation) of Equation 5 is cos θ
, The response of the system changes depending on the value of cos θ. In particular, when θ> 90 °, the value of cos θ is negative, so that the coefficient of the characteristic equation becomes negative and the system becomes unstable. . The above-mentioned disadvantage is that the characteristic equation does not include cos θ by providing the cos θ operation unit 60-3, so that the response characteristic of the azimuth control loop can be made constant regardless of the elevation angle θ of the antenna.

The embodiments of the present invention have been described above.
It will be easily understood by those skilled in the art that the present invention is not limited to the above-described embodiment and can adopt various other configurations without departing from the gist of the present invention.

[0038]

According to the present invention, the value of cos θ is obtained from the elevation angle θ supplied from the elevation angle transmitter 72, and the value of cos θ is obtained.
The value obtained by multiplying the value of θ by the azimuth deviation signal supplied from the adder 61 is used as a gyro drift compensation integrator 60-2.
And outputs the integrator output signal to a 1 / cos θ operation unit 76
, So that the fixed error of the azimuth gyro 45 can be compensated and the response characteristics of the system can be kept constant regardless of the value of the elevation angle θ, so that the pointing accuracy with respect to the satellite is improved. There are benefits that can be made. According to the present invention, since the fixed error of the gyro can be compensated, there is an advantage that an inexpensive angular velocity detecting gyro such as a vibration gyro or a rate gyro can be used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an antenna pointing device according to the present invention.

FIG. 2 is a block diagram illustrating an example of an antenna pointing device according to the present invention.

FIG. 3 is a diagram illustrating an example of a conventional antenna pointing device.

FIG. 4 is a block diagram showing an example of a conventional antenna pointing device.

[Explanation of symbols]

 3 Base 3-1 Bridge section 9-1, 9-1 'Bearing 10 Azimuth axis 10' Cylindrical section 10-1 Arm 11 Azimuth gear 13, 13 'Elevation axis 14 Antenna 16, 16' Elevation axis bearing 40 Azimuth gimbal 40 -1 Support shaft part 40-2 U-shaped part 41 Mounting bracket 41-1, 41-1 'Leg part 44 Elevation gyro 45 Azimuth gyro 46, 47 Accelerometer 48 Elevation gear 49 Elevation angle servomotor 50 Pinion 52 Azimuth servomotor 53 Azimuth Transmitter 54 Integrator 55 Amplifier 56 Attenuator 57 Arc sine calculator 58 Integrator 59 Amplifier 60 Attenuator 61 Adder 72 Elevation transmitter 74 Elevator transmitter gear 76 1 / cos θ calculation unit XX Antenna central axis

Continuation of the front page (72) Inventor Koichi Umeno 2-16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Co., Ltd. (72) Yoshinori Kamiya 2-16-46 Minami Kamata, Ota-ku, Tokyo Stock Company (72) Inventor Kazuya Arai 2-16-46 Minami Kamata, Ota-ku, Tokyo, Japan Tokimec Co., Ltd. (56) References JP-A-62-14504 (JP, A) JP-A-2-299301 (JP, A) JP-A-2-309702 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 3/08

Claims (1)

(57) [Claims] An antenna having a central axis supported by a support member, an azimuth gimbal rotatably supporting the antenna and the support member about an elevation axis orthogonal to the central axis, and an azimuth gimbal supporting the azimuth gimbal. A base rotatably supported about an azimuth axis perpendicular to the axis, a first gyro having an input axis parallel to the elevation axis, and fixed to the support member, and both a center axis and an elevation axis. A second gyro having an orthogonal input axis and fixed to the support member; an accelerometer for outputting a signal indicating an inclination angle of the center axis with respect to a horizontal plane; and a rotation angle of the azimuth gimbal about the azimuth axis An azimuth transmitter for outputting a signal indicating the altitude of the satellite from the output signal of the accelerometer to an effective torquer of the gyro via an attenuator. The output signal of the azimuth transmitter and signals corresponding to the heading azimuth angle and the satellite azimuth angle are calculated by an adder, and the azimuth deviation signal is supplied to the substantial torquer of the second gyro via an attenuator. An elevation angle transmitter configured to feed back and direct the center axis of the antenna toward the satellite, and further output a rotation angle signal indicating a rotation angle θ of the antenna about the elevation axis with respect to the azimuth gimbal; A 1 / cos θ calculation unit for calculating a value of 1 / cos θ from the rotation angle signal output from the elevation angle transmitter, and the output signal of the second gyro and the 1 / cos θ
In the antenna pointing device configured to multiply the output signal of the sθ calculation unit and input the multiplied value to an integrator, whereby the frequency characteristic of the servo system is invariable at all elevation angles θ, A cos θ calculation unit for calculating a value of cos θ from a rotation angle signal output from the transmitter, multiplying the azimuth deviation signal by an output signal of the cos θ calculation unit, and using the multiplication result as a gyro drift compensation integrator And the output signal of the integrator is calculated as 1 / cos
An antenna pointing device, wherein feedback is provided to an input of a θ calculation unit.