JPH03210607A - Analog servo controller - Google Patents

Abstract

PURPOSE:To increase the allowable changing range of an input signal by providing a gain changing means to change in steps the amplification gain of a proportion circuit in accordance with the level of the input signal. CONSTITUTION:A series circuit 15 consisting of a resistance R1 and two diodes 14a and 14b connected in adversely parallel to the R1 is connected in parallel to a feedback resistance R2. The adverse withstand voltage is applied to both diodes 14a and 14b, and this adverse withstand voltage can well withstand the voltage having the large absolute value even though the absolute value E of the both-end voltage of the R2 increases in response to the voltage Vi, i.e. the value of an input signal 5. In this case, the amplification gain of a proportion circuit 16 is changed by a gain changing means 15 despite a big change of the level of the signal 5. Thus it is possible to obtain the position of a control subject where the correct correspondence is always secured between the level of an error signal 4c and the level of the signal 5. As a result, an allowable changing range is increased for the signal 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in a drive mechanism for a laser beam reflecting mirror in a laser processing device to determine the irradiation position of a laser beam on a workpiece by a processing command signal. The present invention relates to an analog servo control device that causes a controlled variable to follow an input signal as a target value, and a device that has a wide allowable variation range of the input signal so that the control device can operate normally.

[Conventional technology]

FIG. 3 is an explanatory diagram of the configuration of a conventional analog servo control device used in a laser processing device.

In the figure, 1 is a galvano scanner as a drive 44 that rotates the mirror device 2 for reflecting the laser beam by an angle 0 according to the value of the input drive signal tOa, 3
is an angle detector configured to detect the rotation angle 6 of the mirror 20 and output an angle signal 3a having a value proportional to this θ;
4 is an operational amplifier to which an input signal 5 as a command signal for angle # is inputted via an inverting input terminal 4aK resistor R4, and a non-inverting input terminal 4b is grounded; in this case, the above angle signal 3m is also input via a resistor B. is input to terminal 41.

Here, the angle signal 3m is a signal having a polarity opposite to that of the input signal 5. R1 is a feedback resistor of the amplifier 4, 6 is a proportional circuit consisting of the amplifier 4 and resistors R, , R, , R, and 7 is a differential signal 8 which differentiates the angle signal 3M with respect to time and is proportional to the result. The output differential circuit 8 calculates the algebraic sum of the differential signal 8a and the output signal 4c of the amplifier 4, and outputs an output signal 9m proportional to this result. This is an arithmetic circuit consisting of a power amplification circuit 10 which performs power amplification using a power amplification circuit and outputs the aforementioned drive signal 10a as a result of the power amplification. Reference numeral 11 denotes an analog servo control device consisting of the parts shown in the figure except for the mirror 2 and the galvano scanner 1 described above.
The above-mentioned parts are configured so that the rotation angle θ of the mirror 2 follows the input signal 5 when the signal 10a is input to the scanner 1. Then, in this case, construct the differentiator circuit 8.

This is provided in order to compensate for the delay in the operation of the laser beam reflection mechanism 12, which is controlled by the control device 11 and is composed of the galvano scanner 1 and the mirror 2, and to improve the coordination of the mechanism 12.

[Problem that the invention attempts to solve]

Since the proportional circuit 6 in the control device 11 is constructed as described above, it is clear that the amplification gain G for the input signal 5 of this circuit 6 is expressed by R, /R. According to the previous experience of those who

This control device 11Vc is configured such that when the gain G is set so that the mirror rotation angle θ correctly follows the signal 5 for a large value of the input signal 5, the mirror 2 is set to the signal 5 for a small value of the input signal 5. The gain G is set larger than in the above case so that the mirror 2 does not touch the angle - corresponding to - and the mirror 2 is insufficiently rotated, and the - correctly follows the signal 5vc for a small value of the signal 5. In this case, when the signal 5, which has a large value, is input to the proportional circuit 6 in a stepwise manner, overshifting, hunting, etc. appear in the angle θ, which changes stepwise over time, resulting in a situation in which - does not follow the signal 5vC correctly. In either case, there is a phenomenon that thermal processing cannot be performed properly using a laser beam (not shown) reflected by the mirror 2. That is, in the control device 11 described above, the gain G of the proportional circuit 6 is fixed, and the input signal 5
The operational amplifier output signal 4 remains constant even if the magnitude of
Since it is not possible to set the magnitude of C to such a value that the mirror rotation angle corresponding to the signal 5vC can be obtained correctly, the value range D( Hereinafter, this range may be referred to as the permissible change range of the signal 5.) There is a problem that this range is narrow.

The purpose of the present invention is to
To obtain an analog servo control device having a wide permissible variation range of the signal 5 by always making the operational amplifier output signal 4C have a size that allows a mirror rotation angle θ that correctly corresponds to the value of the signal 5 to be obtained.

[Means to solve the problem]

In order to achieve the above object, the one-shot BA includes a proportional circuit that amplifies the algebraic sum of an input signal and a feedback signal and outputs an error signal according to the result, and a proportional circuit that temporally differentiates the feedback signal. an arithmetic circuit that outputs a drive signal proportional to the algebraic sum of the differential signal obtained by the differential signal and the error signal; and an arithmetic circuit that detects the position of the controlled object driven by the drive signal and outputs the feedback signal according to the detection result. an analog servo control device that outputs a position detecting section and causes the position of the controlled object to follow the input signal, the amplification gain of the proportional circuit being changed in stages according to the magnitude of the input signal. An analog servo control (capital) device is constructed by providing a gain changing means for changing the gain.

[Effect]

With the above configuration, even if the magnitude of the input signal changes significantly, the amplification gain of the proportional circuit is changed by the gain changing means, so that the magnitude of the error signal always corresponds correctly to the value of the input signal. Since the position of the controlled object can be adjusted to a size that allows the position of the controlled object to be obtained, it is possible to obtain an analog servo control device having a wide allowable change range of the input signal.

〔Example〕

FIG. 1 is an explanatory diagram illustrating the configuration of the first embodiment 13 of the present invention, and the difference from FIG. By connecting the series circuit 15 consisting of two diodes 14m and 14b, here [, #r4 diode 141.14bK
is the resistance R1 depending on the voltage Vi as the value of the input signal 5.
Even if the absolute value E of the voltage across the terminal becomes large, a reverse withstand voltage is provided that can sufficiently withstand the voltage having the large absolute value E. Then, 16 in Figure 1
consists of the above-mentioned series circuit 15, resistors R1 to R, and amplifier 4. This is a proportional circuit corresponding to the proportional circuit 6 described above.

In FIG. 1, since the series circuit 15 as described above is provided, now when trying to rotate the mirror 2 in the forward direction, Vi
)o signal 5 is input to the proportional circuit 16, the voltage Vi
Since the absolute value IVil of is small, the output signal of the operational amplifier is 4C.
The voltage V exhibited by Is the absolute value of ? 141, the series circuit 15 is in a non-conducting state and the gain G for the signal 5 of the proportional circuit 16 is G■ equal to Rt /Ra, but the absolute value IV
When il becomes large and the absolute value of the output voltage vo exceeds the voltage V3, the diode 14a becomes conductive 1olK, so the gain G1 becomes equal to G, , c expressed by equation (1).

In this case, it is clear that Gil>GII.

Gtt=(RI R1/'(Rs"RI)l/R%
-*-・(1) That is, in FIG. 1, Vi
>O input to the circuit 16, if IVNI is small, signal 5 will be amplified with a large gain G
When l is large, signal 5 is amplified by a small gain G1, which means that when signal 5 with Vi < 0 is input to circuit 16 in order to rotate mirror 2 in the opposite direction, 1V
When ll is small and the absolute value IVo+ of the output voltage vo is smaller than the upper layer voltage V of the diode 14b, the series circuit 1
5 is non-conductive, IVil increases and becomes 1v0
1 is V.

When the temperature exceeds that level, the diode 14b becomes conductive, so
The same holds true when the signal 5 with Vi<O is input manually to the circuit 16.

゛Therefore, in the analog servo control device 13, e
! , IVil is small and the series circuit 15 is in the non-conducting state a, the proportional circuit 16 is adjusted so that the value v0 of the signal 4C becomes a value that allows the mirror rotation angle θ to correctly correspond to the value v1 of the signal 5. Gain G1. If you set IVil
When becomes large, the series circuit Is becomes conductive M4VC, and the gain G of the proportional circuit 16 becomes smaller than the above G
Because of the IK, mirror rotation angle 00 overshading or hunting, which is caused by the large IVil being amplified by the large gain 01m as in the conventional control device 11 described above, does not occur, and even if the IVil becomes large, the rotation can be maintained. Signal 4C that angle 0 follows V4ec correctly
As a result, in the control device 13, even if the value Vi of the signal 5 changes significantly.

Always the value V of signal 4C. However, since θ is set to a value that correctly corresponds to ViVc, the control device 13 is an analog servo control device with a wide allowable variation range of the signal 5.

In the control device 13, as described above, the proportional circuit 16
In this case, it can be said that the series circuit 15 constitutes a gain changing means for changing the gain G1 in stages according to the magnitude Vi of the signal 5. Therefore, if the control device 13 is configured, even if the magnitude Vi of the signal 5 changes significantly, the gain G1 of the proportional circuit 16 can be changed by the gain changing means 15.

Since the magnitude vo of the signal 4C can always be made large enough to obtain the rotation angle θ that correctly corresponds to Vl, it is possible to obtain a control device with a wide permissible variation range of the signal 5. Become.

FIG. 2 shows a proportional circuit 18 in a second embodiment 17 of the present invention.
The difference from the above-mentioned proportional circuit 16 in this diagram is a diode anti-parallel circuit 19 in which diodes 191 and 19b are connected in anti-parallel, and a diode anti-parallel circuit in which diodes 20a and 20b are connected in anti-parallel. A series circuit 21 consisting of a circuit 20 and a resistor R is connected in parallel with feedback resistors R and c.
It has been continued. The parts of the analog servo control device 17 according to the second embodiment except for the proportional circuit 18 are constructed in the same manner as in the servo control device fIt13 described above. In the control device 17, since the proportional circuit 18 is configured as described above, in this case, the series circuit 21 and the series circuit $1!15 are connected to the series circuit 15 in the case of FIG. 22 is formed, and it is clear that by this means 2, the gain of the proportional circuit 18 is changed in approximately three steps depending on the magnitude Vl of the input signal 5. Therefore, also in the case of the sa control device 17.

Due to the above gain changing means 22, the magnitude V of the signal 4C remains unchanged even if vi changes significantly. Since it is possible to always obtain a mirror rotation angle θ that correctly corresponds to Vi, this device 17 is also an analog servo control device with a wide allowable variation range of the signal 5.

In each of the embodiments described above, the gains of the proportional circuits 16 and 18 are changed in stages according to the magnitude Vl of the input signal 5 by gain changing means using diodes, but in the present invention, The gain changing means may be formed using the above-mentioned diode (an alternative circuit breaker and a voltage detector that detects Vi and drives the circuit breaker according to the detection result).

〔Effect of the invention〕

As described above, the present invention includes a proportional circuit that amplifies the algebraic sum of an input signal and a feedback signal and outputs an error signal according to the result, and a differential signal obtained by temporally differentiating the feedback signal. and an arithmetic circuit that outputs a drive signal proportional to the algebraic sum of and an error signal, and (2) detects the position of a control object driven by this drive signal and outputs the feedback signal according to the detection result. An analog servo control device comprising a position detection section and making the position of a controlled object follow an input signal, the device comprising a gain changing means for changing the amplification gain of the proportional circuit in stages according to the magnitude of the input signal. An analog servo control device was constructed.

Therefore, with the above configuration, even if the magnitude of the input signal changes significantly, the amplification gain of the proportional circuit is changed by the gain changing means, so that the magnitude of the error signal is always
The present invention has the effect of providing an analog servo control device with a wide permissible change range of input signals because the size of the control object can be adjusted to a position that correctly corresponds to the value of the input signal. .

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram illustrating the configuration of a first practical example of the present invention. FIG. 2 shows lI21! of the present invention! The block diagram of the proportional circuit in an example. FIG. 3 is an explanatory diagram illustrating the configuration of a conventional analog servo control device. 3... Angle detector (position detection section), 3...
・・Angle signal (feedback signal), 4C・・・・
- Operational amplifier output signal (error signal), 5... Input signal, 6.16°18... Proportional circuit, 7...
... Arithmetic circuit, 81 ... Differential signal, 10m
...... Drive signal, 11.13.17...
Analog servo control device, 12... Laser beam reflection mechanism (controlled object), 15... Series circuit (gain changing means). 22... Gain changing means, 0... Rotation angle (position). Note 2

Claims (1)

[Claims] 1) A proportional circuit that amplifies the algebraic sum of an input signal and a feedback signal and outputs an error signal according to the result, and an algebra between a differential signal obtained by temporally differentiating the feedback signal and the error signal. an arithmetic circuit that outputs a drive signal proportional to the sum; and a position detection section that detects the position of a controlled object driven by the drive signal and outputs the feedback signal according to the detection result, An analog servo control device for causing the position of a controlled object to follow the input signal, characterized in that it includes gain changing means for changing the amplification gain of the proportional circuit in stages according to the magnitude of the input signal. Analog servo control device.