JPH0762707B2 - Method of controlling tracking speed of moving body by light beam - Google Patents

Description

The present invention relates to a method of tracking a moving body using a light beam, and in particular to a light beam capable of performing stable tracking even when the movement of the moving body changes suddenly. The present invention relates to a method for controlling a tracking speed of a moving body.

<Prior Art> Conventionally, as a device for tracking a moving body using a light beam,
A light beam generator, a light beam scanning means, a retroreflector provided on a moving body, a light receiving detector for receiving and detecting a light beam reflected and reflected by the retroreflector, and a controller for controlling the light beam scanning means by this detection output. Some are equipped with. The outline of the apparatus and the tracking method will be described below.

FIG. 8 is a schematic explanatory view showing an outline of a conventional device. The fixed station 10 of this device includes a scanning unit 100 and a control unit 300. The scanning means 100 includes a light beam generator 110 that generates a light beam LB, a scanning mechanism 120 that emits the light beam LB generated from the light beam generator 110 toward a space and scans the space, and a moving body 20. It is configured by a light receiving detector 130 that detects the feedback beam RB that is reflected by the retroreflector 200 provided and returns.

More specifically, the light beam generator 110 and the light receiving detector 130 are integrally configured so that their optical axes are the same, and are fixed by a support frame 121 with a shaft. The attached support frame 121 is rotatably supported by the frame body 122. The scanning mechanism 120 is formed in a U shape,
It has a Y-axis pulse motor 124 for rotating the frame body 122 which supports the shaft-supporting frame 121 in the Y-axis direction and an X-axis pulse motor 123 for rotating the frame body in the X-axis direction. Then, the light beam LB from the light beam generator 110 scans the space by the scanning mechanism 120. On the other hand, in the moving body 20,
A retroreflector 200 such as a corner cube is provided,
The scanned light beam LB enters, is reflected by the retroreflector 200, and returns to the fixed station 10 as a return beam RB.

The light receiving detector 130 detects the positional deviation of the return beam RB, and is formed by arranging a large number of light receiving element groups in a quadrant in a plate having a through hole 131 in the center thereof.

When the tracking is completed, the light beam LB is incident on the center of the retroreflector 200, and its return beam RB recurs in the same direction as the light beam LB. The light receiving detector 130 does not detect the received light. When the tracking is off, the return beam RB is displaced, does not pass through the passage hole 131, and the light receiving detector 1
30 detects light reception.

The light receiving element group of the light receiving detector 130 is predetermined by coordinates, and the control unit 300 causes the scanning mechanism 120 to rotate in a direction in which the positional deviation of the return beam RB becomes zero according to the detection signal defined by the coordinates. As described above, the X-axis pulse motor 123 and the Y-axis pulse motor 124 are controlled so that the light beam LB always tracks the center of the retroreflector 200.

FIG. 9 is a block diagram of the control unit 300 of the conventional device. The control unit 300 uses the light receiving position sensor 132 as the light receiving detector 130, and uses the X-axis and Y-axis polarity determination circuits 301, 302, X.
Axis, Y-axis motor drive circuits 303 and 304, speed setter 305, and speed signal generation circuit 306. The light receiving position of the return beam RB detected by the light receiving position sensor 132 is X
A light receiving position signal is input to each of the X-axis and Y-axis polarity determination circuits 301 and 302. X-axis and Y-axis polarity determination circuits 301 and 302 determine the tracking direction by determining the positive / negative polarity determined by the quadrant of the light receiving position signal, and the X-axis and Y-axis motor drive circuits 303 and 304 as tracking direction signals. Entered in.

The speed signal generation circuit 306 outputs a tracking speed signal,
The scanning means 100 can perform tracking at a tracking speed preset by the speed setting device 305.

This tracking speed signal is used for the X-axis and Y-axis motor drive circuit 30.
Input to 3, 304. This circuit rotates the X-axis pulse motor 123 and the Y-axis pulse motor 124 in the directions indicated by the tracking direction signals X and Y at a speed corresponding to the tracking speed signal. As a result, the scanning mechanism 120 is rotated, and the direction of the light beam generator 110 is controlled so that the light beam LB is incident on the central portion of the retroreflector 200 of the moving body 20.

<Problems to be Solved by the Invention> In the conventional tracking speed control method for a moving body using a light beam, the moving speed of the moving body is faster than the preset tracking speed of the light beam generating means. In this case, the light beam deviates from the retroreflector of the moving body, and the moving body cannot be tracked. In order to avoid such a state, it is possible to increase the tracking speed of the scanning means. However, when the tracking speed is set to a constant value at a high speed, the moving body starts, stops, or changes direction, when the movement or moving direction of the moving body suddenly changes, tracking becomes unstable,
In some cases, there is a problem that tracking becomes impossible.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a tracking speed control method for a moving body using a light beam that can stably track even if the movement or the moving direction of the moving body changes suddenly.

<Means for Solving the Problem> A tracking speed control method of a moving body by a light beam according to the present invention is a tracking speed control method of a moving body by a light beam for tracking a moving body from a fixed station, wherein the fixed station is A light beam generator, a light beam scanning means for scanning a light beam emitted from the light beam generator toward the space, and a light receiving detector for receiving and detecting a return beam reflected by a retroreflector provided in a moving body and returning. And a control unit that controls the light beam scanning means by determining the moving direction of the moving body based on the detection output of the light receiving detector, and the control unit is a feedback beam detected by the light receiving detector. The difference between the angular velocity of the moving body as seen from the center of rotation of the light beam scanning means and the angular velocity of the scanned light beam is obtained from the change in the light receiving position of the light beam scanning means, and the tracking speed of the light beam scanning means is adjusted so that this angular velocity difference becomes zero. It is characterized in that the acceleration and deceleration are controlled.

<Operation> The light beam generated from the light beam generator is emitted toward the space and scanned by the scanning means. When this light beam is incident on the retroreflector provided on the moving body, it returns as a return beam. Due to the movement of the moving body, the light receiving position of the light receiving detector for the return beam is displaced. The direction of change of the light receiving position is discriminated by the polarity discriminating circuit, and the discrimination result is input to the motor drive circuit as a tracking direction signal. On the other hand, the difference between the angular velocity of the moving body viewed from the center of rotation of the light beam scanning means and the angular velocity of the scanned light beam is obtained from the amount of change in the light receiving position. This angular velocity difference is input to the velocity signal generation circuit as an acceleration / deceleration signal, and the output of the velocity signal generation circuit is input to the motor drive circuit as a tracking velocity signal. Then, the motor drive circuit drives the X-axis and Y-axis pulse motors according to the tracking speed signal, and controls the tracking speed of the scanning means so that the angular speed difference becomes zero.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic explanatory view showing an outline of a tracking device used in the present invention.

The fixed station 10 of the tracking device according to the present invention is composed of the scanning means 100, the control unit 400, and the retroreflector 200 provided on the moving body 20. The scanning means 100 and the retroreflector 200 have the same configuration as in the prior art, and detailed description thereof will be omitted. As shown in FIG. 2, the control unit 400 is the control unit 300 of the conventional device shown in FIG.
Registers 403, 404, 405, 406 and subtractor 40 on the input side of
7, 408 and acceleration / deceleration determination circuits 409, 410 are added. Other than the above, the configuration is the same as the control unit 300 of the conventional device.

Next, a tracking speed control method for a moving body using this tracking device will be described.

The light beam LB generated from the light beam generator 110 passes through the through hole 131.
And is launched into space and scanned. When the scanned light beam LB is incident on the center of the retroreflector 200, it returns as a return beam RB in the same direction as the light beam LB and goes to the passage hole 131. If tracking is complete,
The light receiving position sensor 132 does not detect the return beam RB, or receives the return beam RB evenly in all quadrants of the light receiving position sensor 132. Then, when the moving body 20 tries to move out of the state of complete tracking, the return beam RB deviates from the passage hole 131 and enters one of the light receiving elements of the light receiving position sensor 132.

The position of the light receiving element of the light receiving position sensor 132 is predetermined by the coordinates and is detected as a detection signal set at the coordinates. For example, when the position of the light receiving element is in the first quadrant, both the X-axis and Y-axis directions have a positive polarity, and the light receiving position signal outputs the rotating direction of the scanning mechanism 120, that is, the tracking direction signal as right and up.
When the light receiving position is the origin of the coordinates, the light receiving position signals are both zero, and the tracking direction signal is output as zero.

The detection signal of the light receiving position sensor 132 is input to the polarity determining circuits 401 and 402 as a light receiving position signal and output as a tracking direction signal. Further, the light receiving position signal is subtracted from the subtracters 407 and 4
It is input to 08 and held by the registers 403 and 405. When a new light receiving position signal accompanying the movement of the moving body 20 is input to the registers 403 and 405, the previous old light receiving position signal is shifted to the registers 404 and 406.

The subtracters 407 and 408 register the new light receiving position signal from the register.
Decrease the previous old light receiving position signal held in 403, 405,
This absolute value is output as the amount of change in the light receiving position and input to the acceleration / deceleration determination circuits 409 and 410. Acceleration / deceleration discrimination circuit 409, 410
If the amount of change in the light receiving position is positive, it is determined to be acceleration, if it is zero, it is determined to be constant speed, and if it is negative, it is determined to be deceleration.
The determined acceleration / deceleration signal is output to.

Next, the speed signal generation circuits 413 and 414 output tracking speed signals for accelerating and decelerating the rotation speeds of the X-axis pulse motor 123 and the Y-axis pulse motor 124 based on the signals. The X-axis and Y-axis motor drive circuits 415 and 416 drive the X-axis pulse motor 123 and the Y-axis pulse motor 124 based on the tracking signal and the tracking speed signal.

That is, the control unit 400 scans the angular velocity of the moving body as viewed from the rotation center of the light beam scanning means 100 according to the change in the light receiving position of the return beam RB detected by the light receiving detector 130 and the time between the changes. The difference between the angular velocity of the light beam and the angular velocity of the light beam is obtained, and the optical beam scanning means is set so that the angular velocity difference becomes zero.
Controls the tracking speed of 100.

When the moving body 20 stops, the tracking speed is reduced, and the tracking operation is performed at the minimum tracking speed set by the minimum speed setting devices 411 and 412.

FIG. 3 is a block diagram of the control unit 500 showing a different embodiment, and shows a case where the light receiving direction sensor 133 is used as the light receiving detector 130. The control unit 500 is obtained by adding subtracters 501 and 502 to the input side of the control unit 400 shown in FIG. 2, and other parts are the same as the control unit 400.

The light receiving element signals detected by the light receiving direction sensor 133 are subtracted by the subtracters 501 and 502 for each quadrant facing the origin.
Entered in.

When the return beam RB deviates from the origin of the light receiving direction sensor 133, the subtractor 501, 50 is detected from the light receiving signal of the light receiving direction sensor 133.
Reference numeral 2 outputs the received light amount difference in the vertical and horizontal directions as a received light amount difference signal. Direction sensor 133 for receiving return beam RB
When light is received in two quadrants facing each other, the amount of deviation of the center of the return beam RB from the origin is proportional to the received light amount difference. Therefore, the change in the light receiving position of the feedback beam RB can be known by comparing the magnitudes of the received light amount difference signals. The received light amount difference signals from the subtractors 501 and 502 operate in accordance with the control unit 400, and the other signals also operate in accordance with the control unit 400, and thus detailed description thereof will be omitted.

FIG. 4 is an operation explanatory view of the light receiving position sensor 132, FIG. 4 (A) is a plan view of the light receiving position sensor 132, and FIG. 4 (B) is a graph showing the relationship between the deviation amount and the tracking speed. FIG. 5 is an operation explanatory view of the light receiving direction sensor 133, (A) is a plan view,
(B) is a graph showing the relationship between the received light amount difference and the tracking speed.

In FIG. 4A, assuming that the light receiving position of the return beam RB received by the light receiving position sensor 132 is P and the light receiving position change amount from the origin 0 is d, as shown in FIG. Until reaching the outer edge r of the light receiving position sensor 132,
Since the light receiving position change amount d gradually increases, it is necessary to increase the tracking speed v to return to the origin 0. However, after passing the outer edge portion r, the return beam RB is not received and the light receiving position P cannot be discriminated, so that the tracking is stopped. Therefore, the tracking speed v suddenly changes to zero as shown by the broken line in FIG. Therefore, the operations of the X-axis pulse motor 123 and the Y-axis pulse motor 124 become unstable. Therefore, in this case, it is necessary to provide a correction circuit having the characteristics shown by the solid line in FIG.

On the other hand, the light receiving direction sensor 133 detects the light receiving position change amount d by the received light amount difference for each quadrant. For convenience of explanation, the light receiving direction sensor 133 will be described as being controlled separately in the upper and lower two quadrants as shown in FIG. 5 (A).

As shown in FIG. 5 (A), the difference in received light amount is
When the light receiving position sequentially moves in the direction of the arrow in the drawing from the position where the center of the beam is received at the origin 0 (indicated by the broken line in the figure), the received light amount difference is increased until the outer peripheral edge of the return beam RB reaches the position P1 where it touches the origin 0. Gradually increase. The received light amount difference is constant until the outer peripheral edge of the return beam RB reaches the position P2 inscribed in the outer edge portion r of the light receiving direction sensor 133. Further, when the position changes from the inscribed position, the position gradually decreases, and the position circumscribes the outer edge portion r.
It becomes zero at P3. In the light receiving direction sensor 133,
The light receiving position change amount d and the tracking speed v are the same.

Therefore, the tracking operation is stopped after the tracking speed command signal is also gradually reduced. Therefore, in the light receiving direction sensor 133,
The correction circuit described above is not necessary because the abrupt change unlike the light receiving position sensor 132 does not occur.

FIG. 6 is a block diagram of a control unit 600 showing another embodiment,
3 is a simplified control circuit of a control unit 500 shown in FIG. That is, the register, the subtractor, and the acceleration / deceleration determination circuit are omitted from the control unit 500. In the present embodiment, the speed signal is not calculated from the change amount of the received light amount difference of the light receiving direction sensor 133, but the distance from the origin of the light receiving position is directly changed to the speed signal.

FIG. 7 is a schematic explanatory view showing one embodiment of the light receiving direction sensor 133. One light receiving direction sensor 133 is arranged in each quadrant on a plane orthogonal to the optical axis, and a condenser lens 134 is provided in front of the light receiving direction sensor 133. The condenser lens 134 is divided into four quadrants, and the return beam RB passing through each quadrant is imaged on the corresponding light receiving direction sensor 133. Further, a passage hole 131 for mounting the light beam generator 110 or for passing the light beam LB is provided at the center of the condenser lens 134. The light receiving direction sensor 133 according to the present embodiment can receive and detect the direction of the return beam RB in units of quadrants, and based on this, the direction of the moving body 20 can be determined. Further, the amount of change in the light receiving position between the origin and the return beam RB can be determined from the ratio of the light amounts of the return beam RB incident in a pair of quadrants that face each other across the origin. Therefore, as compared with the light receiving position sensor 132, the light receiving detector can be constructed at a lower cost.

<Effects of the Invention> As described above, according to the present invention, the light beam is scanned from the fixed station, and the return beam reflected and reflected by the retroreflector provided on the moving body is detected by the light receiving detector and detected. The angular velocity difference between the moving body and the scanned light beam is obtained from the change in the receiving position of the return beam, and the tracking velocity of the light beam is accelerated or decelerated based on the difference. Further, since the moving body is provided with the retroreflector, the change in the light receiving position can be accurately detected by detecting the return beam. Therefore, the tracking speed of the light beam can be smoothly changed according to the speed of the moving body. Further, stable tracking operation is possible even when the movement of the moving body changes suddenly, and the upper limit of the tracking speed can be set higher than that of the conventional one without acceleration / deceleration control.

[Brief description of drawings]

1 to 7 are drawings relating to the present invention, FIG. 1 is a schematic explanatory diagram of a tracking device, FIG. 2 is a block diagram of a control unit, FIG. 4 is an operational explanatory diagram of a light receiving position sensor, and FIG. FIG. 7 is an operation explanatory view of the light receiving direction sensor, FIG. 6 is a block diagram of a control unit showing a different embodiment of FIG. 3, FIG. 7 is a schematic explanatory view showing another embodiment of the light receiving direction sensor, and FIG. FIG. 9 and FIG. 9 are schematic explanatory views of a conventional tracking device. 100: scanning means 110: light beam generator 120: scanning mechanism 132: light receiving position sensor 133: light receiving direction sensor 200: retroreflector 400, 500, 600 ... control unit

Claims (1)

[Claims] 1. A method for controlling a tracking speed of a moving body using a light beam for tracking a moving body from a fixed station, wherein the fixed station directs a light beam generator and a light beam emitted from the light beam generator to a space. Light beam scanning means for scanning, a light receiving detector for receiving and detecting a return beam reflected by a retroreflector provided on the moving body, and a light receiving device for detecting the moving direction of the moving body based on the detection output of the light receiving detector. A control unit for controlling the beam scanning unit, and the control unit determines the angular velocity of the moving body as seen from the center of rotation of the light beam scanning unit from the change in the light receiving position of the return beam detected by the light receiving detector. And the angular velocity of the scanned light beam, the tracking speed of the light beam scanning means is controlled so that the angular velocity difference becomes zero. Control method.