JP2649513B2 - High precision positioning device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital servo type high-precision positioning device.

Conventional technology In this type of digital servo system, a rotary encoder is directly connected to a motor to be controlled, and a pulse of a predetermined frequency corresponding to a command speed pattern is input from a control circuit such as a CPU to a reversible counter as a feed command value. You.
The reversible counter receives a command pulse as an input, an output pulse of the rotary encoder as a feedback signal, and outputs a deviation thereof to a speed servo amplifier of the motor via a DA converter. Thus, the speed servo amplifier drives the motor using the voltage proportional to the number of pulses of the reversible counter as the speed signal.

During this time, if the deviation of the reversible counter becomes "0", the speed signal also becomes "0" following the deviation, and the motor automatically stops at the target position.

The stop accuracy of the motor to be controlled corresponds to one pulse of the rotary encoder and the control circuit. Therefore, higher accuracy of the stop position can be achieved by increasing the resolution of the rotary encoder. However, when the resolution of the rotary encoder is increased, the number of pulses per rotation of the motor is correspondingly increased. Therefore, unless the capacity of the reversible counter is increased, appropriate measures cannot be taken. In addition, the resolution of the DA converter and the speed servo amplifier must be increased accordingly, which requires a design change of the control system and the servo system itself. There is a limit to practical application in relation to the target.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to increase the positioning accuracy of a controlled object at the time of stopping, without increasing the resolution of the components of the control system and the components of the feedback system.

Therefore, the present invention focuses on two-phase pulses of a rotary encoder, compares a combination state of the two-phase pulses with a previously designated pulse phase, and, according to a matching state of these comparison results, The stop position of the control target is determined.

To realize this, the present invention interposes a stop controller between the reversible counter as the first comparing means and the DA converter, and uses the second comparing means in the stop controller. , The set value and the phase of the two-phase signal from the rotary encoder are compared. And the stop control means in the stop controller,
The count value of the reversible counter is “0” and the second
Only when the comparison result of the comparison means is the same, the control signal for stopping is sent to the subsequent control system. As a result, in such a control system, the stop area corresponding to one deviation of the count value is divided by the number of combinations of the two-phase pulse outputs. Even if it is not configured, the positioning accuracy at the time of stopping will be improved.

If the count value of the reversible counter is other than "0", the stop controller sends the position deviation of the reversible counter to the DA converter at the next stage as it is. Therefore, the control other than the stop operation operates in the same manner as the conventional digital servo system.

FIG. 1 shows a digital servo type high-precision positioning device 1 according to the present invention. This high-precision positioning device 1
Is a reversible counter 2 as first comparing means having a command value A as one input, a stop controller 3, a DA converter 4, and a speed servo amplifier 5 as characteristic parts of the present invention.
Further, motors 6 are sequentially provided in series as rotating members to be controlled.

A speed detector 7 of a speed servo system is connected to the motor 6.
And a rotary encoder 8 of a digital feedback system are mechanically connected. The speed detector 7 is a tacho generator or the like, and is connected to an addition point 9 on the input side of the speed servo amplifier 5. The rotary encoder 8 outputs a two-phase pulse with a phase difference of 90 degrees, for example, to detect the rotation direction of the motor 6.
B1 and B2 are generated and sent to the other input terminal of the reversible counter 2 via the stop controller 3 and the encoder interface 10.

Next, FIG. 2 shows an internal configuration of the stop controller 3. The stop controller 3 has a zero detection circuit 13 in addition to a data selector 11 as stop control means and a magnitude comparator 12 as second comparison means.

The data selector 11 is constituted by a ROM or the like, and a plurality of, for example, 3
"0" pattern, "+1" pattern and "-1"
A pattern or the like is stored, and one of the patterns is selectively output according to the comparison result of the magnitude comparator 12. The zero detection circuit 13 is interposed between the reversible counter 2 and the data selector 11 and detects a position where the motor 6 should stop, that is, a count value “0”. The magnitude comparator 12 is composed of a CPU or the like, and outputs a set value H input in advance and a pulse output from the rotary encoder 8.
It is provided to compare the magnitude relation between B1 and B2 and to specify the selection operation of the data selector 11 according to the result. Note that the exciter-OR gate 14 on the input side of the magnitude comparator 12 is provided to align the actual phases of the pulse outputs B1 and B2.

First, the operator sets one input terminal of the magnitude comparator 12 at one input terminal of the magnitude comparator 12 as a set value H in which a phase relationship between a plurality of pulse outputs from the rotary encoder 8 is defined in advance, for example, a definition of “1, 0 = 2”. Is entered.
Further, the operator sets a numerical value B having a magnitude as shown in the table below for the four combinations of the pulse outputs B1 and B2, and sets the control signal G to the data selector 11 as "0" pattern and "-1" pattern. , And the “+1” pattern are stored.

First, a command value A is supplied to one input terminal of the reversible counter 2 from the control circuit side to the control system. In this initial state, since the count value C is not “0”, the count value C passes through the stop controller 3 as it is,
The signal is converted into an analog signal D by the DA converter 4 and sent to the speed servo amplifier 5. Therefore, the speed servo amplifier 5 generates a drive signal E proportional to the command signal D, thereby determining the rotation speed of the motor 6 to be controlled and rotating it. The rotational speed of the motor 6 is detected by a speed detector 7 and is fed back as a speed feedback signal F to a combining point 9. on the other hand,
The rotation amount of the motor 6 is determined by the rotary encoder 8.
The pulse output B1 is detected as the number of pulses of the pulse outputs B1 and B2 as shown in FIG. Thus, the count value C of the reversible counter 2 becomes a deviation value corresponding to the difference between the set value A and the actual rotation amount.
Is controlled in a state proportional to the deviation value.

By the way, when the count value C of the reversible counter 2 becomes “0”, the motor 6 is in the stop area shown in FIG.
In the stop area, a non-positioning state occurs. In this state, the zero detector 13 detects the count value C of “0” as a coincidence signal and gives the data selector 11 one condition for stop control.

On the other hand, the magnitude comparator 12
Numerical value B and set value H based on the combination of B1 and B2
Are compared with each other, and a match signal is output to the data selector 11 as another selection condition at the time of a match according to the comparison result.

Therefore, the data selector 11 outputs a “+1” pattern from the control signal G when (H−B)> 0, and outputs a “−1” pattern when (H−B) <0. When a coincidence signal is generated, that is, when (H−B) = 0, a “0” pattern is output as a control output for high-precision positioning stop.

As a result, as shown in FIG.
, Ie, the range of the count value C = 0, is divided into four, and the stop position of the motor 6 is determined in the divided stop range (the range of generation of the control output of the pattern of “0”).
Therefore, the positioning accuracy of the motor 6 in this control system is
This is four times higher than the conventional one. Moreover, the actual stop position can be set freely within a range of 1/4 of the count value C = 0 by setting the numerical value of the set value H.

Note that, as described above, the above-mentioned extrude or gate 14 has a relation of “0 → 1 → 3” in relation to the setting of the numerical value B.
It is provided to change the change of “→ 2” into the relation of “0 → 1 → 2 → 3”, and may be omitted as necessary.

Modified Example of the Invention The above embodiment uses the two-phase pulse outputs B1 and B2 from the rotary encoder 8, but the number of pulse outputs having different phases is not limited to two phases and is three or more. Is also good. As the number of phases increases in this way, the number of divisions of the stop area increases accordingly, and a stop position with high accuracy can be secured. The data selector 11 is composed of a ROM or the like as a general circuit element. However, for the two-phase pulse outputs B1 and B2 as in the above-described embodiment, a simple ex- cessive OR gate and a pattern are used. It can also be realized by a combination of a generation circuit and the like.

According to the present invention, the positioning accuracy of the controlled object is increased according to the number of divisions of the stop area without increasing the accuracy of the control elements of the digital control system and the feedback system. Since it can be put into practical use only by adding a stop controller to the system, high-precision positioning accuracy can be realized at low cost and with only a partial improvement of the conventional device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a high-precision positioning device of the present invention,
FIG. 2 is a block diagram of the stop controller, and FIG. 3 is a waveform diagram during operation. 1. High precision positioning device 2. Reversible counter 3.
... Stop controller, 4 ... DA converter, 5 ... Speed servo amplifier, 6 ... Motor, 8 ... Rotary encoder, 11
... Data selector, 12 ... magnitude comparator, 13 ... zero detection circuit.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-100818 (JP, A) JP-A-61-120968 (JP, A) JP-A-59-208614 (JP, A) JP-A-56-100 121108 (JP, A)

Claims (1)

(57) [Claims] 1. A rotary encoder provided on a rotating member for generating a plurality of phase-shifted pulse outputs, a command value and a pulse output value of the rotary encoder are compared.
A first comparing means for generating a coincidence signal when the two coincide with each other, wherein the positioning device controls the stop of the rotating member by the coincidence signal of the first comparing means. Second comparing means for comparing a set value defining the phase relationship with the phase of a plurality of pulse outputs from the rotary encoder; and the first comparing means until the first comparing means outputs the coincidence signal. While sending the output of the comparison means to the next stage as it is,
The output of the second comparing means is input, the first comparing means outputs the coincidence signal, and the second comparing means outputs the set value and a plurality of signals from the rotary encoder. And a stop control unit for outputting a control output for stopping the rotating member when a coincidence signal in which the phase of the pulse output coincides is output, wherein the coincidence signal of the first comparison unit and the second A high-precision positioning device, wherein the rotating member is stopped according to a coincidence signal of a comparing means.