JPS5946004B2 - Positioning control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to holes drilled or filled in an object to be controlled.
By detecting printed circular marks and matching them with the control head, it is used in conjunction with general X-Y axis positioning control to perform precision positioning when inserting pins, machining, and printing. This relates to a method for carrying out this process.

In general, positioning by numerical control is often sufficient for the above-mentioned control applications, but if the machining accuracy of the workpiece is not sufficient, or if the position and dimensions have shifted due to aging, numerical control may be sufficient. In contrast to primary positioning by control positioning, secondary positioning is required in which the difference between the position of the object and the desired position is directly detected, and the positions are moved to match precisely.

Various positioning methods have been devised to match a controlled point on a plane with a target point, but it is difficult to realize a positioning method that has a simple configuration and can compensate for secular changes in position detection elements, etc. There is a problem.

The purpose of the present invention is to solve such problems, and the purpose is to provide a positioning method for aligning a controlled point within the scanning plane with a target point located at the center of the scanning plane.
With the target point at the center of the scanning plane as the origin,
A scanning means that sets an orthogonal coordinate system consisting of axes and alternately scans a slit parallel to each axis in the X and Y axis directions within the plane, and detects when this slit passes a target point and a controlled point. a counting means capable of counting the scanning time interval between the target point and the controlled point that occurs for each scan in the positive and negative directions; and a digital/analog converting means that converts the value counted by the counting means into a voltage. and a servo driving means for causing the controlled point to approach the target point at a speed proportional to the voltage generated from the converting means, so that the detection signals of the target point and the controlled point generated by the scanning means are temporally coincident. This is achieved by controlling the situation in a way that makes it possible.

Next, details of the present invention will be explained with reference to the drawings.

The present invention is used, for example, for the purpose of automating the process of inserting a pin 13 slightly smaller than the hole diameter into a workpiece 1 having a large number of holes in a plate-like material as shown in FIG.

FIG. 2a shows a schematic plan view of a positioning device according to an embodiment of the invention, and FIG. 2b shows a side view thereof.

In the figure, 1 is a workpiece, 2 and 3 are work tables forming an X-Y table, 4 and 5 are servo motors, 6 is a pin insertion mechanism, 7 is a scanning mechanism, 8 is a scanning disk, 9 is a motor, 10 to 12 are light receiving elements, 13 is a pin, and 14 is a light source lamp. Table 2 is driven by a servo motor 4, and table 3 is driven by a servo motor 5 in the direction of the arrow through feed screws.

The table 2 is placed on the table 3 and is moved left and right as the table 3 moves in the left and right direction. The pins 13 are supplied one by one from the pin insertion mechanism 6 and inserted into holes in the workpiece.

At this time, it is necessary that the center of the pin 13 and the center of the hole in the workpiece correspond precisely. If the hole position is accurate, it is sufficient to align the centers by driving the X-axis and Y-axis servo motors 4 and 5 through numerical control, but if the hole position is slightly uneven, If it has shifted due to aging, it is necessary to optically search for the actual hole position and correct it to accurately align it with the center of the pin 13. For this reason, in this device, the light source lamp 1 is
4, the light passes through the through hole and hits the pin 13 position, and the light receiving element 10 is placed there to match the pin position and the hole position. The procedure for the pin insertion operation of this device is as follows.

(1) First, the pin insertion mechanism 6 is moved back so as not to interfere with the detection of the light beam passing through the pin position. (2) Next, the servo motors 4 and 5 are driven externally by numerical control to move the tables 2 and 3 to align the holes in the workpiece with the pin positions.

(3) Next, for precise alignment of the pin position and hole position,
The detection element 10 detects the light beam coming from the light source lamp 8 through a desired hole in the workpiece 1, and drives the servo motors 4 and 5 to move the tables 2 and 3 in order to precisely match the hole position and the pin position. control.

At this time, the servo motor is disconnected from the numerical control device and connected to a control circuit that is connected to the detection element 10 and will be described later.

(4) When the alignment is completed, the pin insertion mechanism 6 returns to the pin insertion position, inserts the pin 13 into the desired hole, and completes the operation.

The above sequence of operations is repeated to insert pins one after another.

Next, the operation of the control circuit connected to the detection elements 10 to 12 will be described in detail.

The principle of the system of the present invention will be explained with reference to FIG.

The purpose of the method of the present invention is to perform precise positioning after rough positioning as described above. Therefore, the target point and the positioning target point are located close to each other within several distances. This method scans the two holes, the target point and the controlled point, alternately in the X-axis and Y-axis directions, and measures the scanning time interval between the two points.
The key point is to drive the servo motor at a speed that corresponds to the time difference.

FIG. 3 explains the scanning method, in which the seven windows 5 that define the scanning range cover a certain range centered on the target point 16, and this is due to the above-mentioned primary positioning. It is designed to push 17. The control method of the present invention is to make points 16 and 17 in FIG. 3 coincide.

Create an X-Y coordinate system with the target point 16 in Figure 3 as the origin,
The slit 18 parallel to the Y axis (hereinafter referred to as the slit for scanning in the X-axis direction) and the slit 19 parallel to the X-axis (hereinafter referred to as the slit for scanning in the Y-axis direction) alternately scan the XllllIY-axis direction (arrows in the figure). do.

Although the scanning means of this embodiment uses mechanical scanning, an electronic method such as a semiconductor video conversion device may also be used.
For example, when scanning in the Y-axis direction, the slot opening 9 for scanning in the Y-axis direction is used.
runs from top to bottom, and when the Y-axis scanning slit 19 cuts through the center 16 of the window 15, it emits a pulse indicating the center. Further, a detection output is made to be output when the slit 19 cuts the controlled point 17. When such scanning is performed alternately on the X and Y axes, the center pulse and detection pulse appear at time intervals as shown in FIG. The time interval between both pulses appearing during the Y-direction scanning period is proportional to the distance between the target point 16 and the controlled point 17 in the Y-direction.

Scanning in the X-axis direction is also performed in the same way, and the time difference τY that appears at this time is the time it takes for the slit 19 to move the distance in the Y direction from the center point 16 to the controlled point 17, and the time difference τX is the time difference τX that appears from the center point 16 to the controlled point 17. The time taken for the slit 18 to move the distance in the X direction to the point 17 is shown. When this time is counted and the counted value is converted into digital/analog and applied as a voltage to the servo motors for driving the X and Y axes, the servo motors rotate at a speed proportional to the deviation, so-called integral control is performed.

The servo motor rotates until the center pulse of the target point and the detection pulse of the controlled point overlap and τX=τY=O. An example of a control circuit diagram for performing the above control is shown in FIG.

In the figure, 20 is a counter control circuit, 21 is a reversible counter, 22 and 23 are buffer and D/A conversion circuits, and 24
, 25 indicates a servo motor drive circuit. The inputs to the counter control circuit 20 are the detection pulse and center pulse shown in FIG. If a pulse, the first pulse to start scanning in the X-axis direction, is output, the counter control circuit 20 controls the reversible counter 2
1 to "0" and wait for a pulse.

When the center pulse appears first, the counter control circuit 20 gives a forward counting instruction to the reversible counter 21 and starts counting. This count may be operated by a clock, for example, 1 MPPS. The counter increments, and when a detection pulse arrives after a delay time of τX, it stops counting and transfers the contents of the counter 21 to the X-axis buffer and A/D conversion circuit 22.
and wait for the next Y-axis scan pulse to arrive.

The output of the A/D conversion circuit 22 is sent to the servo motor drive circuit 24.
The servo motor 4 is driven through the feed screw to rotate the feed screw in the direction in which X becomes smaller. If the detection pulse appears before the center pulse, the counter control circuit 20 instructs the reversible counter 21 to count in the negative direction (i.e., minus count), and the count result is sent to the A/D conversion circuit 21.
2, the X-axis servo motor 4 rotates in the negative direction,
Similarly, the servo motor is driven in the direction in which τX becomes smaller. Note that the operation of the Y-axis servo motor 5 is performed in the same manner. This control method will be explained in more detail with reference to FIG.

In (1), the central pulse is delayed by τ1 from the detection pulse, but it is decreased to τ2 and τ3 by controlling.

Then, positioning ends when both pulses match. However, in general, the time widths of both pulses often do not match as shown in FIG. In such a case, (1) in Figure 5 → (
As shown in 2)→(3), the pulses gradually approach each other, and as shown in (4), there is a time difference of τ4 between the rising edges of both pulses, and their falling edges become coincident. In this case, the servo motor is rotated to further reduce τ4, and the difference in falling time between both pulses is made to match the time difference on the rising side. This can be done, for example, by starting counting at the rising edge of the longer pulse, stopping counting at the rising edge of the shorter pulse, then subtracting the previous count value at the falling edge of the shorter pulse, and counting the longer one. Counting is stopped at the falling edge of the pulse. At this time, when the count value reaches IO'', both pulses match.
In other words, τ5′ shown in 5::. When τ55=O, the counter is finally aligned to 202. In this embodiment, a mechanical scanning system is used, and the details of the scanning mechanism 7 shown in FIG. 2 will be explained below. This scanning mechanism 7 includes a light source lamp 14 that passes light from below the desired hole position, a light receiving element 10 that receives this light, a scanning disc 8 that performs scanning and creates timing signals, a motor 9 that drives the disc, It is composed of a lamp for generating a timing signal and light receiving elements 11 and 12. A detailed view of the scanning disk 8 is shown in FIG. The rotation of the scanning disk is detected by a combination of a light source lamp and a light receiving element to generate various signals, which are input to a counter control circuit 20 shown in FIG. 6 for positioning control. Next, the scanning operation will be explained with reference to FIG.

The scanning disk 8 is a rotating disk as shown in FIG. 7, and has an even number of scanning slits and various timing detection holes.

In the figure, a detection head having a light receiving element 10 is placed at a position corresponding to the center of the square area of the window 15 to be scanned, and this position is the target point for positioning.

There are five tracks in the form of concentric circles on the disk 3, and the seventh
Placed as shown.

The scanning track 26 passes through the detection head position, and this track 26 becomes the center of the scanning slit in the X and Y directions. On the outside, in order, there is a Y-axis direction center pulse detection hole arrangement track 27, an X-axis direction center pulse detection hole arrangement track 28, and a Y-axis direction scan start pulse detection hole arrangement track 2.
9X-axis direction scanning start pulse detection hole arrangement track 30-4
There is a track of the book. The required number of slits and detection holes are provided on the disk 8, and their functions will be explained below.
The slit for scanning in the X-axis and Y-axis directions is the center of scanning, and has the function of scanning the inside of the window 15 alternately in the X-axis and Y-axis directions.

This divides the circumference into 2n equal parts (in the figure, it divides into 8 equal parts), and the normal line and
This is a narrow slit that passes through the intersection of the scanning tracks and is cut at an angle of ±45 to the normal. This slit is window 15
If the window is sufficiently small, the slit will scan alternately in the X-axis and Y-axis directions. This scanning is actually performed in a fan-shaped manner, but since the area of the window is sufficiently small, it can be thought of as alternating scanning in the X and Y axis directions as shown in FIG. In FIG. 7, the slit for scanning in the X-axis direction scans the center of the window 15, and the slit for scanning in the Y-axis direction scans the center of the window, as shown by dotted lines.

The light receiving element 10 is designed to detect all light within the window. When the slit crosses the hole at the controlled point in the window, the detection output shown in FIG. 4 is obtained according to its position. Next, a center pulse indicating that the slit has passed through the center 16 of the window 15 is transmitted through the center detection holes of the disk tracks 27 and 28 in FIG. 12 and a photodetector 11.

The center detection holes in the X and Y axis directions are opened at the intersections of the extension lines of the X and Y axis scanning slits and the tracks, respectively.

A light source lamp is placed under the disk so that the center pulse shown in FIG. 4 is obtained when the X and Y axis direction scanning slit scans the center of the window 15, and the scanning slit cuts the center of the window. Sometimes a central pulse can be obtained. Tracks 29 and 30 in FIG. 7 have holes for generating the Y-axis scan start pulse and the X-axis scan start pulse used to switch between the X-direction scan and Y-direction scan shown in FIG. It's dawn.

The hole drilled in the track 29 is detected by a detector 32 located at the position shown in FIG. 7, and a Y-axis direction start pulse is generated. Similarly, a hole made in the track 30 is detected by the detector 31, and an X-axis direction scan start pulse is generated.

These X and Y axis scanning start pulses are used to switch the X and Y axis scanning control, and are generated before the X and Y axis scanning slits start scanning the window 15, respectively. It is. In this embodiment, each axis is scanned four times per rotation, but the number of scans can be increased by increasing the number of divisions. The scanning method using this disk can be summarized as follows.

It is assumed that the scanning disk 8 is rotated in the direction of the arrow and the hole of the controlled point is set in the window by primary positioning.

When the control circuit shown in FIG. 6 receives a command to start control, this circuit prepares to receive a scan start pulse in the X and Y axis directions.
When the disk rotates and the X-axis or Y-axis selection hole arrives at a predetermined detection position, the light-receiving element photoelectrically detects this and sends an X- or Y-axis scan start pulse to the counter control circuit 20.

The control circuit 20 enters either the X or Y scanning section shown in FIG. 4 and waits for the arrival of the detection pulse and center pulse. When the disk 8 rotates and enters the frame of the window 15, and the slit scans inside the window and passes through the hole at the controlled point, the light projected from below the hole at the controlled point passes through the slit. The light hits the light receiving element 10 of the detection head and generates a detection pulse.

Also, when the slit passes through the center of the window 15, a center pulse is generated. The control circuit 20 calculates the temporal relationship between the detected pulse and the center pulse, creates a servo motor control signal, and sends this to the X or Y axis servo motor drive circuit 24 or 25.
, the control is terminated, and the next scanning pulse for the other axis arrives.

In this way, the scanning in the X and Y axis directions is controlled while being alternately switched, and the operation is repeated until the detection pulses in both the X and Y axes and the center pulse coincide with each other.

When both axes are aligned in this manner, a signal indicating completion of positioning is generated, and the pin insertion mechanism 6 shown in FIG. Ru. As mentioned above, this method uses 11 detection elements to perform scanning in the X and Y axis directions and detect the center. The light emitted from one of the holes in the disk can be applied by placing, for example, two mirrors arranged at right angles on the other side of the disk, and shining the light onto the sharp corner of the disk to direct the light from side to side. Compared to a method in which the light is divided into two equal parts and a photodetecting element is placed on each optical path of the divided light, there is no effect of changes in the characteristics of the elements.

2. Orthogonal axis control can be easily performed with one rotating plate.

Since the control circuit 3 essentially performs digital processing, there is no influence from drift, and since integral control is performed, the offset can theoretically be set to 0I.

Therefore, the positioning control system of the present invention has a simple configuration and can realize a highly reliable positioning system that is not affected by aging.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an application example of the positioning method according to the present invention,
FIG. 2a is a schematic plan view of a positioning device according to an embodiment of the present invention, FIG. 2b is a side view, FIG. 3 is a diagram explaining the principle of the positioning method of the present invention, and FIGS. 4 and 5 are center views. A time chart of pulses and detection pulses, FIG. 6 shows a positioning control circuit diagram according to an embodiment of the present invention, and FIG. 7 shows a detailed view of the scanning disk 8 in FIG. 2. In the figure, 1 is the workpiece, 2 and 3 are the work tables, and 4
, 5 is a servo motor, 6 is a pin insertion mechanism, 7 is a scanning mechanism, 8 is a scanning disk, 9 is a motor, 10 to 12 are light receiving elements,
13 is a pin, 14 is a light source lamp, 15 is a window, 16 is a target point, 17 is a controlled point, 18 is a slit for scanning in the X-axis direction,
19 is a slit for scanning in the Y-axis direction, 20 is a counter control circuit, 21 is a reversible counter, 22 and 23 are buffer and D/A conversion circuits, and 24 and 25 are servo motor drive circuits.

Claims (1)

[Scope of Claims] 1. In a positioning method in which a controlled point located within a scanning plane is made to coincide with a target point located at the center of the scanning plane, the X and Y axes are aligned with the target point located at the center of the scanning plane as the origin. A scanning means that alternately scans a slit parallel to each axis in the X and Y axis directions within the plane, and detects when this slit passes a target point and a controlled point. a detection means, a counting means capable of counting in positive and negative directions the scanning time interval between the target point and the controlled point that occurs for each scan;
The scanning means has a digital/analog converting means for converting the value counted by the counting means into a voltage, and a servo driving means for causing the controlled point to approach the target point at a speed proportional to the voltage generated from the converting means. 1. A positioning control system comprising: a control means for stopping the servo drive means when detection times of detection signals of a target point and a controlled point generated by the above coincide in time. 2. A patent that determines that the detection times of the detection signals of the target point and the controlled point coincide by matching the centers of the detection pulse widths generated when passing the target point and the controlled point in the scanning plane. A positioning control system according to claim 1. 3 Divide the rotating disk into an even number of equal parts in the circumferential direction, provide slits in the direction rotated 45 degrees in the forward and reverse directions with respect to the normal direction, and arrange the slits in the forward and reverse directions alternately. The slit scans the inside of a small window provided in the area through which the slit passes, and each time the slit passes through the center of the window, a target point detection pulse is obtained from the center pulse generation mechanism provided on the rotating disk. A positioning control system according to claim 1 or 2, characterized in that: