JPH087621B2 - Dual servo controller for optical space transmission system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser beam azimuth control technique when communication with a moving body is performed by an optical space transmission method.

[Prior Art] FIG. 7 shows, for example, the Society of Instrument and Control Engineers, vol.23, No.
It is a perspective view which shows the structure of the conventional azimuth | direction control apparatus of a laser beam reported by 10, PP.1017-1023 (1987).
However, since a photograph was published in this document, the Robotics Society of Japan vol.6, No.1, PP.26-
34 (1988). In the figure, (2)
Is a laser beam, (9) is a laser oscillator, (10) is a tracking mirror, (41) is a collimating lens, (42) is a right-angle prism, (43) is a half mirror, (44) is a total reflection mirror, (45). ) Is two stepping motors with harmonic gears that drive this tracking mirror (10) with two orthogonal axes, (46) is a corner cube provided at the other end of communication, and (47) is a returned laser A lens for condensing the beam (2), and (48) is a two-dimensional position sensor for detecting the position of the returned laser beam (2).

 Next, the operation will be described.

In FIG. 7, a laser beam (2) emitted from a laser oscillator (9) is tracked through a collimating lens (41), a right-angle prism (42), a half mirror (43) and a total reflection mirror (44). Enter the center of the mirror (10). The tracking mirror (10) has two orthogonal stepping motors (4
5) driven by harmonic gear. As a result, the laser beam (2) can be controlled in any direction in the three-dimensional space. When the laser beam (2) irradiates the corner cube (46) on the other side, the reflected light from it diverges by twice the amount of deviation from the center of the corner cube (46) and is returned to the tracking mirror (10). Be done. Then, after passing through the total reflection mirror (44) and the half mirror (43), it is condensed by the lens (47) and detected by the two-dimensional position sensor (48). The light receiving position information of the two-dimensional position sensor (48) and the angle information of the tracking mirror (10) calculated from the operation amount of the stepping motor (45) are input to a microcomputer (not shown). The microcomputer determines the operation amount of the stepping motor (45) from the input information, and controls the tracking mirror (10) so that the laser beam (2) is directed to the center of the corner cube (46).

Figures 8 (a) and 8 (b) show corner cubes (46), respectively.
At a distance of 10 m, radius 0.26 m, angular velocity 57.3 deg / s
2 is a follow-up characteristic of two orthogonal axes of the stepping motor (45) when rotated by, the horizontal axis represents time, the vertical axis represents the deviation angle, and FIG. 8 (a) shows the pan (horizontal) direction, FIG. 8B shows a shift angle in the tilt (vertical) direction. It can be seen that when the rotation is constant, it follows within ± 0.01 deg. However, at the beginning of rotation, the corner cube (46) has a large acceleration, and thus the tracking error is large.

[Problems to be Solved by the Invention] Since the conventional laser beam azimuth control device is configured as follows, there is a problem that a tracking error becomes large for a moving body having a large acceleration.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a dual servo control device for an optical space transmission system having high-speed response and high resolution at the same time.

[Means for Solving the Problems] A dual servo control device for an optical space transmission system according to the present invention detects the position of a received laser beam by an optical position detector, and detects the beam position detected by the optical position detector. According to the difference between the set command position and the set command position, the precision deflection system rotates the tracking mirror that controls the deflection of the emitted laser beam, and the rotation angle of the tracking mirror output from this precision deflection system is detected by an angle sensor. According to the rotation angle, the tracking mirror is rotated coaxially with the precise deflection system by a coarse deflection system having a resolution coarser than that of the precision deflection system.

[Operation] The dual servo control device of the optical space transmission system according to the present invention uses two types of actuators having different resolutions and controls both at the same time, thereby achieving high-speed response and high resolution at the same time.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a dual servo control device of an optical space transmission system according to an embodiment of the present invention.
In FIG. 1, (3) is an optical position detector that detects the position of the received laser beam, and (21) is the disturbance d caused by the traveling of the moving body. (22) is the deviation of the beam position detected by the optical position detector (3), (23) is the command input of the dual servo controller set to u = 0, (24) is the proportional gain G _2p ′, the integral It is a proportional- _plus- integral controller with a gain G _2i . (25) is a precision deflection system having a transfer function H ₂ (s), which rotates a tracking mirror that controls the deflection of the emitted laser beam. (26) is the rotation angle θ ₂ of the tracking mirror output from the precision deflection system (25), and (27) is the rotation angle Q ₂ (2
An angle sensor for detecting 6), (28) is a proportional controller having a proportional gain G _1p , (29) is a coarse deflection system having a transfer function H ₁ (s), and is coaxial with the precision deflection system (25). Then, the tracking mirror is rotated. (30) is the rotation angle θ ₁ of the tracking mirror output from the rough deflection system (29), and (31) is the distance L between two opposing communication stations.

FIG. 2 is a configuration diagram showing a basic configuration of the optical space transmission system. In FIG. 2, (1) is a transmission / reception unit for communication, (2) is a laser beam emitted from the transmission / reception unit (1), and (3) is an optical position for detecting the position of the received laser beam (2). A detector, (4) is a deflection system that controls the direction of the laser beam (2), (5) is an attitude variation generator that gives attitude changes to the communication station, and (6) is a moving body that moves the communication station. The two communication stations have the same structure and are installed opposite to each other. For example, the robot station (7) provided on the moving body (6) and the relay station (8 installed opposite to it). ) Consists of.

FIG. 3 is a configuration diagram showing a basic configuration of a deflection system that realizes a laser beam azimuth control operation in an optical space transmission system. In FIG. 3, (2) is a laser beam,
(3) is an optical position detector for detecting the position of the laser beam (2) provided on the communicating side, (9) is a laser oscillator, and (10) is tracking for controlling the direction of the laser beam (2). A mirror, (11) a first axis coarse deflection system for controlling the direction of the laser beam (2) in the pan (horizontal) direction, (12)
Is a second-axis coarse deflection system for controlling the orientation of the laser beam (2) in the tilt (vertical) direction. These coarse deflection systems are, for example, direct drive motors. (13) is a pan (horizontal) with a higher resolution than the coarse deflection system (11) of the first axis
(1) is a precise deflection system for the first axis in the vertical direction, and (14) is a precision deflection system for the second axis in the tilt (vertical) direction having a higher resolution than the coarse deflection system (12) for the second axis. as,
For example, there is a piezo actuator with a resolution of 0.006 ° or more. Two communication stations facing each other have the same structure, and although not shown in FIG. 3, an optical position detector (3) is provided for the communication station controlling the direction of the laser beam (2). However, a laser beam (2) is required for a communication station with an optical position detector (3).
A system for controlling the bearing is provided.

Further, FIG. 4 is a configuration diagram showing a configuration example of the precision deflection system and the angle sensor, which is shown in one of the pan (horizontal) direction and the tilt (vertical) direction. Fourth
In the figure, (15) is a fulcrum, (16) is a piezo actuator, and (17) is an interval sensor, and the rotation angle of the tracking mirror (10) is detected by detecting the interval with the tracking mirror (10). . (18) attaches the tracking mirror (10) to the fulcrum (1
5) A spring that supports the piezo actuator (16) together.

 Next, the operation will be described.

In FIG. 2, the transceiver unit (1) of the robot station (7)
The laser beam (2) emitted from the tracking mirror (10)
And the position is detected by the optical position detector (3) of the relay station (8). The result is transmitted from the transmission / reception unit (1) of the relay station (8), received by the transmission / reception unit (1) of the robot station (7), and fed back to the deflection system (4) that controls the orientation of the laser beam (2). To be done. The same operation is performed on the laser beam (2) emitted from the relay station (8). The laser beam (2) can be provided with several wavelengths, and communication data can be used from that wavelength as appropriate. It is also possible to use one wavelength for the application detected by the optical position detector (3). The posture variation generating section (5) is provided on the moving body (6), and gives a sine wave angular variation about two orthogonal axes in the back surface of the moving body (6) to simulate a posture variation due to leg walking. To do.

In FIG. 3, a laser beam (2) emitted from a laser oscillator (9) is reflected by a tracking mirror (10) and passes through the tracking mirror (10) to a coarse deflection system (1) for the first axis.
1), second axis coarse deflection system (12), first axis precision deflection system (1
Azimuth is controlled by 3 actuators of 3) and the second axis precision deflection system (14). For the first axis coarse deflection system (11) and the second axis coarse deflection system (12), for example, a direct drive motor is used when high speed is required. The first-axis precision deflection system (13) and the second-axis precision deflection system (14) are, for example, piezo actuators. The laser beam (2) irradiates the optical position detector (3) provided on the other side of the communication, and the deviation between the center of the optical position detector (3) and the center of the laser beam (2) is x.
The deviation (horizontal direction) and y deviation (vertical direction) are output. This output is transmitted from the other side by an optical transmitter and an optical receiver (not shown) and used for controlling the direction of the laser beam (2). The optical position detector (3) is composed of, for example, a four-division type photodetector in which four photodetectors are combined.

Next, the control operation will be described for one of the pan direction and the tilt direction.

In FIG. 1, the disturbance d (21) is caused by the movement of the moving body.
Occurs, the difference from the deviation up to that point is detected as the deviation (22) by the optical position detector (3). This deviation (22) is fed back, and the difference between the set command input (23) and u = 0 is passed through the proportional-plus-integral controller (24),
Proportional-integral processing is performed, and it becomes a command value for the precision deflection system (25), and the precision deflection system (25) starts following with the tracking mirror (10). The feedback is performed by using the two transmitting / receiving units (1) in the optical space transmission system, but it is not essential as a system of the dual servo control device. Precision deflection system (25)
The rotation angle θ ₂ (26) of the tracking mirror (10) output from the sensor is detected by the angle sensor (27). FIG. 4 shows an example of the configuration of the precision deflection system and the angle sensor. The piezo actuator (16) is driven on one side of the fulcrum (15) according to the output value from the proportional-plus-integral controller (24), and the tracking mirror. (10) tilts. On the other hand, on the opposite side of the fulcrum (15), the displacement of the tracking mirror (10) is detected, for example, by a capacitance type interval sensor (17) without contact, and the rotation angle of the tracking mirror (10) is obtained. This rotation angle is proportionally processed through the proportional controller (28), and this value is given to the coarse deflection system (29) as a command value. In response to this, the coarse deflection system (29) is replaced by the precise deflection system (25).
On the same axis as, and starts moving in the same direction as the precision deflection system (25),
The rotation angle of the tracking mirror (10) is always returned to zero so that the precision deflection system (25) does not deviate from the movable range.
The coarse deflection system (29) outputs the rotation angle θ ₁ (30), and the rotation angle of the tracking mirror (10) seen from the absolute coordinate system is (θ1 +
θ ₂ ). Then, this (θ ₁ + θ ₂ ) and the disturbance d
The tangent tan (θ ₁ + θ ₂ −d) of the difference from (21) multiplied by the distance L (31) between the communication stations is detected as the deviation (22) by the optical position detector (3). Where precision deflection system (25)
Although the command value θ ₂ (26) output from the coarse deflection system (29) is angle data, the coarse deflection system (29) uses this value as the speed command value.

It is also possible to insert a filter at an appropriate position in FIG. 1 in order to improve the characteristics of the dual servo control device by eliminating the resonance of the mechanical system.

The control operation has been described above. The deviation (22), the coarse deflection system (29), and the precise deflection system (25) are the x deviation and the first axis coarse deflection system in the pan (horizontal) direction, respectively. (1
1) corresponds to the first axis precision deflection system (13), and in the case of tilt (vertical) direction, y deviation, second axis rough deflection system (12), second axis precision deflection system ( It corresponds to 14).

FIGS. 5 (a), (b), (c), and (d) are follow-up characteristics when the moving body (6) is running, which are obtained by the dual servo control device according to the embodiment of the present invention. In the experiment, the distance between the communication stations (7) and (8) was 3 m, and the moving body (6)
The control is started when the robot is at rest, and the posture fluctuation at a frequency of 1 Hz is gradually increased to an amplitude of 10 ° (section A). When the posture change reaches a steady state, move the moving body (6) at a speed of 2.5 km / h.
To drive (section B). And the distance between communication stations is 9m
Then, the traveling of the moving body (6) was stopped, the posture fluctuation was gradually reduced, and stopped (section C). Fig. 5 (a)
The measurement results shown in (b), (c) and (d) are the robot stations (7) which are the communication stations provided on the moving body (6).
And the deviation signal of the optical position detector (3) of the relay station (8) which is a communication station installed opposite to it. As a result, since the deflection system (4) of the robot station (7) is directly subjected to the posture variation, the x deviation and the y deviation (22) detected by the relay station (8) are large (Fig. 5 (a)). )
(B)). The output of the optical position detector (3) is 7.5mm at 2.5V.
It is confirmed that the tracking error is 6 mm or less even in the y deviation of the relay station, which has the largest tracking error, and high-speed and highly accurate azimuth control of the laser beam (2).

In the above embodiment, as the controller for outputting the command value to each deflection system, the proportional-integral controller for the precision deflection system and the proportional controller for the coarse deflection system were used. As shown, this may be replaced with an integral controller (28) for the precision deflection system (25) and a proportional-integral controller (24) for the coarse deflection system (29).

EFFECTS OF THE INVENTION As described above, according to the present invention, the position of the received laser beam is detected by the optical position detector, and the difference between the beam position detected by the optical position detector and the set command position is detected. According to the precision deflection system, the tracking mirror that controls the deflection of the emitted laser beam is rotated, and the rotation angle of the tracking mirror output from this precision deflection system is detected by the angle sensor, Accordingly, the tracking mirror is rotated coaxially with the precision deflection system by a coarse deflection system having a resolution that is coarser than that of the precision deflection system. Therefore, it is possible to always achieve high-speed response and high resolution at the same time. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a dual servo control device of an optical space transmission system according to an embodiment of the present invention.
FIG. 4 is a block diagram showing the basic constitution of an optical space transmission system according to an embodiment of the present invention, FIG. 3 is a constitution diagram showing the basic structure of a deflection system according to the embodiment of the present invention, and FIG. 5A, 5B, 5C, 5D, 5D, 5E, 5D, 5E, 5D, 5E, 5D, 5E, 5D, 5E, 5D, 5E, 5D, 5E, 5D, 5D, 5E, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, 5D, and 5B are respectively shown in FIGS. FIG. 6 is a characteristic diagram showing the obtained tracking characteristic, FIG. 6 is a block diagram showing a dual servo control device of an optical space transmission system according to another embodiment of the present invention, and FIG. 7 is a conventional laser beam azimuth control device. 8A and 8B are characteristic diagrams showing the tracking characteristics obtained by the conventional laser beam azimuth control device. (1) is a transmitter / receiver, (2) is a laser beam, (3) is an optical position detector, (4) is a deflection system, (10) is a tracking mirror,
(11) is a first axis coarse deflection system, (12) is a first axis precision deflection system, (13) is a second axis coarse deflection system, (14) is a second axis precision deflection system, (16) ) Is a piezo actuator, (17) is a distance sensor, (22) is a deviation, (24) is a proportional-integral controller, (2
5) is a precision deflection system, (27) is an angle sensor, (28) is a proportional controller, and (29) is a coarse deflection system. In the drawings, the same reference numerals indicate the same or corresponding parts.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04B 3/60 10/10 10/105 10/22 (56) References JP-A-55-142307 ( JP, A) JP-A-58-90442 (JP, A)

Claims (1)

[Claims] 1. A light position detector for detecting the position of a received laser beam, a first proportional-plus-integral controller for inputting a difference between a beam position detected by the light position detector and a set command position, A precision deflection system that rotates a tracking mirror that controls the deflection of the emitted laser beam according to the output value of the first proportional-plus-integral controller; an angle sensor that detects the rotation angle of the tracking mirror output from the precision deflection system; The second proportional controller for inputting the output value of the angle sensor, and the precision deflecting system having the resolution for rotating the tracking mirror coaxially with the precision deflecting system according to the output value of the second proportional controller. Dual servo controller for optical space transmission system with coarser deflection system.