JPH03264911A - Light beam control mechanism - Google Patents

Abstract

PURPOSE:To allow an assured tracking, etc., in optical communication by using a voice coil type motor by mounting a mirror for controlling light beam which deflects the light beam past an aperture in the biaxial directions X-Y to the rear surface of a Y-axis gimbal. CONSTITUTION:A control current flows perpendicularly to the magnetic flux by a permanent magnet 10 of the X-axis gimbal 6 when the control current is applied to the coil 4 for driving the X-axis gimbal of a non-friction bearing driving part 2 of a stationary base 1. The driving torque rotating around the X-axis is, therefore, generated by an elastic pivot 3 as the voice coil type motor by Fleming's left-hand rule. The permanent magnet 10 generates the driving torque in the same direction around the X-axis at all times in this case. The X-axis gimbal 6 is controlled in rotation without friction in the X-axis gimbal 6 is controlled in rotation without friction in the X-axis in such a manner. The light beam control mechanism which allow the taking of a wider control range, has the resolving power equiv. to the resolving power of a piezoelectric element and is adequate for space communication machines is obtd. in this way.

Description

[Detailed Description of the Invention] [Summary] Optical beam control used for acquisition and tracking technology between space optical communication satellites! Regarding the lateral side, the aim is to realize a light beam control mechanism that can perform capture and tracking using optical communication using a voice coil type motor. and a gimbal drive coil.
Each ' @Two magnetic circuit parts, which are cut out from the permanent magnet and yoke that engage with the frictionless bearing/driver, are provided facing each other, and two frictionless bearings/drivers having the same configuration as the frictionless bearing/driver are mounted on the Y axis. The X-axis gimbal is placed in isolation in a direction opposite to each other, and the X-axis gimbal is suspended by the elastic hinges of the frictionless bearings and drive parts of the X-axis gimbal, and generates a magnetic flux that interlinks with the gimbal drive coil to rotate the Y-axis. A Y-axis gimbal is equipped with a fixed magnetic circuit section consisting of permanent magnets and yokes arranged so as to generate a driving torque in the direction, and a light beam from an opening provided in the fixed base is directed to the back surface of the Y-axis gimbal. The beam is configured to be deflected in two axial directions of X and Y by a light beam control mirror provided in the.

[Industrial application field]

The present invention relates to a light beam control mechanism, and more particularly to a light beam control mechanism used in acquisition and tracking technology between space optical communication satellites.

Space optical communication has been attracting attention in recent years as a means of high-capacity inter-satellite communication or communication in deep space.

In order to establish space optical communications, it is necessary to overcome several technical issues, one of which is light beam control technology. In this case, controlling the light beam means accurately directing the light beam in the direction of the other satellite in accordance with the relative movement between the other satellite, which is the other party of optical communication, and the own satellite.
Pointing) and tracking. Although light has a shorter wavelength than radio waves and is capable of large-capacity communications, extremely high-precision beam control is required to capture and track communication satellites.

In other words, as a milestone for the realization of space optical communications, as shown in Fig.
Considering optical communication with GEO and LEO, the orbital velocities V6VL of GEO and LEO with respect to the earth are given by the following approximate expressions.

vG=r7] T1τ lower: GEO Vt −ur + ht ) : LEO However, the gravitational constant μ=398,6 (131al'/s", and the radius of the earth r=6.378 kll.

Based on the above formula, the values regarding the orbits of GEO and LEO are approximately as shown in the following table.

table Also, the relative angular velocity ω of LEO as seen from GEO.

If both satellites are in the same orbital plane, CO3ω, Δ
t= (r+h s)-(r+h L)CO5(ωL-(
LI G)Δt÷[((r+h*)”+(r+hL)
”2(r+hJ(r+hL)CO5(ωt-ωc)Δt
) ] is given by +/Z. The maximum angular velocity is Maxcω, ) =0.012(deg/5)hL=l
, 000k11.

Here, the round trip time of light between GEO and LEO is approximately 0.25
seconds, GEO receives LEO's beacon light and
By the time the GEO beacon light, which is controlled by determining the direction of O and directing the light beam in that direction, reaches LEO, LEO will have moved a maximum of 2 degrees even if there is no processing delay.

On the other hand, the diffraction angle θ4 of the beacon light is given by 0m-2,44Xλ/D (λ is the wavelength used and D is the antenna diameter), so λ=0.8 μm, D"'30
Even if the beacon light is narrowed down to the diffraction limit of C+l, θ6=6
．． 5 μrad, and a light beam with a diameter of 30 cm is 40 μrad.
, 0OOkn+, it will spread to 260m.

In this case, if a 100-μm semiconductor laser is used, the received power will be 0.13μ even if the propagation loss is zero.
− decreases to

Therefore, widening the beam width to facilitate acquisition and tracking has a limit in terms of received power, but the control range of the optical beam is limited to absorbing random errors such as thermal distortion of the antenna boom and attitude swing. In this case, a beam divergence angle of about 1710 degrees is required, and in this case extremely high precision control of around 1 urad is required.

[Conventional technology and yA problem]

Traditionally, electrical and mechanical methods have been considered as optical beam control methods for performing this type of capture and tracking technology, but the former electrical method requires mechanically movable parts. However, the control range is narrow and there are many technical problems in terms of feasibility.

On the other hand, rotary motors, voice coil motors (VCM), and piezoelectric elements have been proposed as mechanical methods for the latter, but although rotary motors can control beams over a wide range, they lack resolution. The bearing part! Rubbing is a problem, and the piezoelectric element is in a 7 degree opposite relationship with the rotary motor.

On the other hand, voice coil type motors, although not as good as rotary type motors in terms of control range, have the advantage that they can be wider than piezoelectric elements, have comparable resolution, and can have frictionless bearings.

Therefore, the present invention provides an optical beam control system that uses a voice coil motor to perform capture and tracking in optical communication.
The purpose is to realize an Il structure.

[Means to solve the problem]

FIG. 1 shows the optical beam system of the voice coil type motor of the X-Y two-axis mounting type according to the present invention to achieve the above object. 11 shows the overall configuration of the 11 mechanism.

In the figure, at the bottom is a gimbal fixing base l using a two-axis mounting method. This fixed base 1 has an aperture 5 (a square aperture in the figure, but a circular aperture may also be used) according to the diameter of the light beam, and a frictionless bearing/drive unit 2 that supports the X-axis gimbal 6 at the top. They are provided at a constant interval in the X-axis direction.

This frictionless bearing/drive unit 2 is composed of a known and easily available elastic pivot 3 and a coil 4 for driving an X-axis gimbal 6. As for the elastic pivot 3, the one disclosed in Utility Model Application No. 1-1447 can also be used.

The X-axis gimbal 6 has a frictionless bearing/drive unit 2 on the fixed base l.
As shown in FIG. 2, the permanent magnet 8 and the yoke 9
There are two magnetic circuit parts 10 consisting of the same structure as the fixed base 1! As shown in the figure, m-bearing/driving units 11 are arranged at regular intervals in the Y-axis direction perpendicular to the X-axis.

As shown in FIG. 2, in the magnetic circuit section 10 of the X-axis gimbal 6, the X-axis gimbal drive coil 4 is inserted into the gap between the permanent magnet 8 and the yoke 9, so that the directions of the magnetic flux of the magnets 8 are opposite to each other. For example, the polarity of N-5 is set from two magnets with opposite polarity, and in the gap between them, a magnetic flux is generated in the rotation direction of the elastic pivot 3 due to the t current flowing through the coil 4 and the interlinking magnetic flux. The driving torques are generated in the same direction.

The Y-axis gimbal 13 in the center is supported in a suspended manner by the elastic pivot 3 of the frictionless bearing/drive section 11 of the X-axis gimbal 6, and has two magnetic circuit sections 1 arranged in the Y-axis direction.
It has 4. This magnetic circuit section 14 has the same configuration as the magnetic circuit section 10 of the X-axis gimbal 6.

Further, a light beam control mirror 15 is attached to the back surface of the Y-axis gimbal 13 for deflecting the light beam that has passed through the opening 5 of the fixed base 1 in two axial directions of X and Y.

[For production]

In FIG. 1, for example, when a control current is applied to the X-axis gimbal drive coil 4 of the frictionless bearing/drive unit 2 of the fixed base l, this control current is applied to the X-axis gimbal drive coil 4 as shown in FIG. Since the magnetic flux flows perpendicularly to the magnetic flux generated by the permanent magnet 10, a driving torque is generated to rotate around the X axis by the elastic pivot 3 as a voice coil type motor according to Fleming's left hand rule. In this case, the permanent magnet 10 always generates a driving torque in the same direction around the X-axis.

In this way, the X-axis gimbal 6 is rotationally controlled in the X-axis direction without friction.

Similarly, regarding the Y-axis gimbal J13, when a control current is applied to the Y-axis gimbal drive coil 12 of the frictionless bearing/drive unit 11 of the X-axis gimbal 6, the drive torque that rotates around the Y-axis is generated, and the Y-axis gimbal 13 is rotationally controlled in the Y-axis direction without friction.

Therefore, the ξ sheath 15 attached to the back surface of the Y-axis gimbal 13 can deflect the light beam input through the opening 5 of the fixed base 1 in the biaxial directions of the χ-Y axes.

〔Example〕

FIG. 3 shows the basic configuration of the entire optical system using the light beam control mechanism according to the present invention, in which 21 is a pointing mirror, and a drive unit 2223 is used to control the direction of an optical antenna (not shown). The orientation is controlled by providing angles (α, βT) from a ground station or a processing system mounted on the satellite.

24 is a double-sided reflective mirror, 25 is a parabolic mirror beam expander, 26 is a tiger 7 king mirror controlled by a control signal from the ground station or on-board of the satellite, 27
-30 is a beam splinter, 31-33 is a condensing lens,
34 is a communication photodetector, 35 is a two-dimensional CCD, 36 is a reflection mirror, 37 is a four-quadrant optical sensor, and 38 is a point-ahead mirror, and the light beam of the present invention shown in FIGS. 1 and 2 This corresponds to the light beam control mirror 15 of the control barrel.

Further, 39 and 40 are collimator lenses, 41 is a semiconductor laser f (LD) that emits beacon light, 42 is a reflecting mirror, and 43 is a communication LD.

FIG. 4 shows an embodiment of the control system of the optical system shown in FIG. 3, and shows an example of the control system for the optical system shown in FIG. (or Y-axis gimbal drive coil 12) is the voice coil motor (
(hereinafter referred to as CM4 for convenience) are a controller 51, a drive circuit 52, and a deflection sensor 53 of the VCM4, which perform, for example, PID compensation control in response to a point-ahead command value.
It is now controlled by. Note that this command value must be used to direct the beam to the predicted position ahead in the direction of movement in order to compensate for the propagation delay of light due to the distance between the satellites and direct the light beam to the target satellite with the desired accuracy. , which indicates a predicted angle commensurate with the predicted position ahead of the movement, and is given from the ground or by onboard instructions from the satellite.

Further, a difference signal between the line-of-sight angle θ7° of the received light beam and the line-of-sight angle θLO5 on the receiving side is sent to a CCD sensor 71 as a pointing sensor and a four-quadrant sensor 72 as a tracking sensor, and its output is Based on the signal, the sensor signal processing section 73 generates a Moro selection signal and switches the switch 74 to the acquisition/tracking mode or the initial acquisition mode.

The switch position of this mode selection switch 74 is initially set to the initial acquisition position, and the controller 54 and the voltage i [
It is separated from the tracking operation by the piezoelectric actuator 56, which is controlled by the piezoelectric actuator 55 and drives the trunking mirror 26.

In other words, the initial acquisition mode is a mode to acquire the target satellite for the first time within a narrow field of view at the initial stage of forming an optical link in space, and is a 3D acquisition mode that predicts the line of sight of the other satellite from the ground or onboard. The torque command value U is converted by the target value generator 57 based on the angle command value derived from the coordinate axis information.

(1), the drive circuit 58. DC motor59. Integrator 6O
, gain controller 61. State estimator 62. In this mode, the pointing mirror 24 is operated by a loop composed of the gain controller 63 and the gain controller 63.

In this loop, the drive circuit 58 that has received the torque command value u c (t) controls the angle of the pointing mirror 24 using the DC motor 59, and changes the angle from the target value 57 to the signal θ, which indicates its current angular position. The deviation θ with respect to the target angle is obtained by subtracting it from the command value θc(1), this is integrated by an integrator 60, and a constant gain is given by a gain controller 61. Based on the deviation θ, a state estimator 62 In order to eliminate the deviation, the position/speed of the motor 59 is estimated by the model (D compensation), a constant gain is added by the gain circuit 63, and a negative addition is performed with the output of the gain circuit 61 to eliminate the estimation error. Torque is generated, and the difference from the torque command value uc(j) is given to the drive circuit 58 again.

In such a loop pointing operation, since the command value is large, only the pointing mirror 24 is operated.This pointing mirror 24 is
In the case of a polar orbit satellite, scanning of ±180 degrees is required, and the tracking mirror 26, which cannot take a large deflection angle, cannot be used as a replacement, so it is used.

Regarding this initial acquisition, the present applicant has already filed a patent application for
-62892.

When the transmission light beam of the partner satellite is successfully received and this initial acquisition operation is completed, the mode selection switch 74 is activated by the ground or onboard command, and the sensor signal processing unit 73 performs acquisition/acquisition operation.
The mode is switched to the tracking mode, that is, the capture mode in which the output of the CCD sensor 71 is selected.

The acquisition signal from the mode selection switch 74, ie, the viewing angle θ of the receiving side. , and the other party's line of sight angle θ,. .

(θ7.T), the controller 54 and voltage source 55 apply a control voltage to the piezoelectric actuator 56 to provide a driving force to the tracking ξ sea 26.

At this time, the tracking angle output θ of the actuator,
is added to the pointing angle output θLO of the DC motor 59, resulting in the receiving angle θLO1.

Also, the viewing angle θL of the reception side detected by the CCD sensor 71. , and the other party's line of sight angle θL (deviation signal θT from I3
The GT is given to the piezoelectric actuator equivalent model 64 and converted into a deflection equivalent signal, and the amount of movement relative to the angle command value is fed back and added to the target value generator 57 again.
The goal is to The deflection equivalent signal generated by this piezoelectric actuator equivalent model 64 becomes smaller as the control progresses, and eventually becomes close to zero.

In this acquisition mode, the viewing angle deviation is relatively large, so
The pointing mirror 24 is mainly driven and controlled, and the angular displacement from the piezoelectric actuator 56 is small.

When the deviation becomes "0" as a result of this acquisition operation, the acquisition mode ends, and the tracking mode is then switched to based on the ground or onboard instruction, and feedback control similar to the acquisition mode is performed based on the output of the four-quadrant sensor 72. . However, in this tracking mode, contrary to the capture mode, the line-of-sight angle deviation is small, so the pointing mirror 24 is hardly driven, and the piezoelectric actuator 56 mainly contributes to control.

As mentioned above, the receiving side's viewing angle θ1° is the receiving side's viewing angle θ? A feedbank is applied to match GT, and at this time, the line of sight angle θ, on the receiving side. .

is the viewing angle θ from the VCM 4 for point-ahead deflection, and the transmitted optical beam viewing angle θa. It will be sent to the other satellite as a satellite.

〔Effect of the invention〕

As described above, according to the light beam control mechanism according to the present invention, the frictionless bearing provided on the fixed base and the elastic pivot of the drive unit and the gimbal drive coil are connected to the permanent magnet provided on the uppermost X-axis gimbal. By frictionlessly engaging the magnetic circuit section consisting of the
Rotational motion in the axial direction is generated, and the frictionless bearing/drive part elastic bipo 7) provided on the X-axis gimbal and the gimbal drive coil are connected from the permanent magnet and yoke provided on the Yllk gimbal at the center. A rotational movement in the Y-axis direction is generated by frictionless engagement with the magnetic circuit section formed by the magnetic circuit, and by flowing a control current through the coil, thereby causing the light beam control mirror provided on the back surface of the Y-axis gimbal to rotate between X-Y. Since it is configured in the form of a voice coil motor to deflect in two axial directions,
The control range is wider than that of a piezoelectric element, the resolution is comparable to that of a piezoelectric element, and the following unique effects can be obtained.

1) Frictionless bearings eliminate the need for lubrication of moving parts.
It has a long lifespan and is suitable for space communication equipment.

2) By arranging the bearing and drive part on the same plane,
The gimbal is stacked to save space, making it smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a light beam control mechanism according to the present invention. FIG. 2 is a partially cutaway perspective view showing a permanent magnet and a yoke used in the light beam control mechanism according to the present invention. , a block diagram showing the entire optical system including the light beam control mechanism according to the present invention, FIG. 4 is a diagram showing the control circuit of the entire optical system, and FIG. 5 is a schematic diagram of the orbit of the communication satellite. In Fig. 1, 1...Fixation base, 2...Frictionless bearing/drive section, 3...Flat pivot, 4...X Tsumugi gimbal drive coil, 5...Opening part, 6 . . . .

Claims (1)

[Claims] A fixing device in which two frictionless bearing/drive units (2) are arranged opposite to each other in the X-axis direction and each has an elastic pivot (3) and a gimbal drive coil (4). It is supported by the stand (1) and each frictionless bearing/drive part (1), and generates a magnetic flux that interlinks with the gimbal drive coil (4) to generate a drive torque in the rotational direction of the X axis. Two magnetic circuit sections (10) consisting of a permanent magnet (8) and a yoke (9) that engage with each frictionless bearing/drive section (2) are provided facing each other, and the frictionless bearing/drive section (2) An X-axis gimbal (6) in which two frictionless bearings and drive units (11) having the same configuration as the 11)
A permanent magnet (8) and a yoke are suspended by the elastic pivot (3) of the yoke and are arranged so as to generate a magnetic flux that interlinks with the gimbal driving coil (12) to generate a driving torque in the rotational direction of the Y axis. (9) The magnetic circuit section (14
) to which a Y-axis gimbal (13) is fixed, and a light beam control device provided on the back side of the Y-axis gimbal (13) to direct a light beam from an opening (5) provided in the fixed base (1). A light beam control mechanism characterized by deflection in two axial directions of X and Y using a mirror (15).