JPH0262609A - Automatic zero control method for servo mechanism of automatic plotter or the like - Google Patents

Abstract

PURPOSE:To reduce the zero control manhour by using a means which corrects automatically the zero output error of a servo mechanism. CONSTITUTION:The value outputted to a D/A converter 38 from a CPU 36 should be set at zero at halt of a picture line head 24. However the CPU 36 outputs the value epsilon equal to the zero control error of a servo mechanism if detected, and the CPU 36 stores this offset value epsilon. Then the CPU 36 sets the stop position of an automatic plotter within a minute setting area based on the position data obtained by adding the value epsilon to the set output when the automatic plotter is moved by a prescribed extent by the set output of the CPU 36. This set stop position is outputted. Thus the head 24 can be stopped within an allowable error range against its target position with no zero control required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic zero adjustment method in a servo mechanism of an automatic drafting machine or the like.

[Conventional technology]

In a servo system for positioning a moving object such as an automatic drafting machine, zero adjustment of the system is performed by manually adjusting a variable resistor so that the CPU output is exactly zero when the servo system is stable when the moving object is stopped. .

(Problems to be Solved by the Invention) When the servo system is configured to perform zero adjustment by one hand operation as described above, the operation is cumbersome, the number of steps required for zero adjustment increases, and reliability deteriorates due to aging. The present invention is aimed at eliminating the above-mentioned defect.

[Means to solve problems]

In order to achieve the above object, the present invention provides a servo mechanism that controls a motor that drives a moving object such as an automatic drafting machine using a set output of a CPU.
When the movable body is moved by a predetermined amount according to the set output of the CPU, the movable body is stored in a small set area before and after the position data obtained by adding the output ε to the set output of the CPU. The stopping position is set.

〔Example〕

The structure of the present invention will be described in detail below with reference to embodiments shown in the accompanying drawings.

Reference numeral 2 denotes a table of an automatic drafting machine, and Y rails 4.6 are fixedly installed on both sides of the table, and Y cursors 8 and 10 are movably attached to the Y rails 4.6. , 10 is the Y servo motor 1 mounted on these
It is configured to move along the Y rails 4 and 6 by a rotation of 2.14. An X rail 16 is installed over the Y cursors 8 and 10, and an X cursor 18 is movably attached to the X rail 16. The X cursor 18 is configured to move along the X rail 16 by rotation of an X servo motor 20 mounted thereon. A drawing head 24 equipped with a pen 22 is attached to the X cursor 18 . The input shaft of a pulse encoder 26 is connected to the output shaft of the X servo motor 20, and the output end of the pulse encoder 26 is connected to the output shaft of the X servo motor 20 via a pulse counter 28 and a digital-to-analog converter 3o.

It is connected to the error detector 32 of the servo mechanism. The output end of the pulse encoder 26 is further connected to a pulse counter 3.
It is connected to a CPU (central processing unit) 36 via 4. The output side of the CPU 36 is connected to the input side of the X motor 20 via a digital-to-analog converter 38, an error detector 32, and a motor drive circuit 40. The servo mechanism of the Y servo motors 12, 14 is also similar to the servo mechanism shown in FIG.

Next, the operation of this embodiment will be explained.

When the servo mechanism of the automatic drawing machine is powered on, the CPU3
6 (by 71 control, x, y motor 20° 12.14
is driven in the mechanical origin return direction. After sufficient time has elapsed for the servo mechanism to stabilize, the printing head 24
When stopped, the digital/analog converter 38 from the CPU 36
The value output in should be zero. However, if the zero adjustment of the servo mechanism deviates, the CPU 36 outputs a value E corresponding to this deviation.
6 stores this offset amount ε, cpU36
sets the movement amount X of the linear head 24 to the target position WE, and outputs X to the digital-to-analog converter 38, the actual stop position of the drawing head 24 is determined by the offset value ε
Therefore, it becomes E'. That is, in the servo mechanism where the position E' is (E-ε), the movement of the drive device is stopped when the difference between the target position and the current position becomes less than a certain value. This value is the so-called in-position area. In an automatic drawing machine, when the in-position area is used as a workpiece, the difference Err between the target position and the current position of the drawing head 24 is usually
It is expressed as being in position when ≦±■. If the above E' is taken as a reference and the range of plus and minus E is taken as in-position, an error due to the tolerance tool will occur in the stop position of the printing head 24 set by the CPU 36. Therefore, in the servo mechanism of the present invention, the one-stroke head 24 is moved from the position E'+ε, that is, from the position E to the plus point.
The time of minus I is defined as in-position, whereby the drawing head 24, ie, the pen 22, stops within the tolerance range for earthworks with respect to the target position WE.

The above explanation is for all positive values, and the printing head 2
The control in the Y direction of No. 4 is also the same as above.

〔effect〕

As described above, the present invention automatically corrects the deviation in the zero output of the servo mechanism, thereby reducing the number of zero adjustment steps, reducing the number of parts, and improving reliability. There are effects that can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram, FIG. 2 is a plan view, and FIG. 3 is an explanatory diagram. 2...Table, 4,6...Y rail, 8,1o・
...Y cursor, 12.14...Y servo motor, 1
6...X rail, 18...X cursor, 20...
X servo motor, 22... Pen, 24... Print head, 26... Pulse encoder, 28... Pulse counter, 3o... Digital/analog converter, 32...
...Error detector. 34...Pulse counter, 36...CPU, 38...
...Digital-to-analog converter, 40...Motor drive circuit.

Claims (1)

[Claims] (1) The motor that drives a moving object such as an automatic drafting machine is powered by a CPU.
In the servo mechanism controlled by the set output of the motor, when the output ε of the CPU is stored when the motor is stopped, and the movable body is moved by a predetermined amount by the set output of the CPU,
An automatic zero adjustment method characterized in that the stop position of the movable body is set within a slight setting area before and after position data obtained by adding the output ε to the set output of the CPU as a reference.