JPS6318413A - Highly precise positioning device - Google Patents

Abstract

PURPOSE:To highly precisely determine the stopping position of an object to be controlled, by providing a stoppage controller between a reversible counter (1st comparison means) and DA converter and comparing a set value with the phase of the two-phase signal of a rotary encoder by means of the 2nd comparison means is the controller. CONSTITUTION:An encoder 8 gives the pulses B1 and B2 of two pulses having a phase difference of 90 deg. to one end of a reversible counter 2 through a stoppage controller 3 and encoder interface 10 in the order of phase. The controller 3 is provided with a data selector 11, a magnitude comparator 12 as the 2nd comparison means, and zero detecting circuit 13. The data selector 11 stores three patterns of control signals G. The magnitude conparator 12 compares a set value H with the combined value of the signals B1 and B2 and, only when the count value C of the reversible counter 2 is zero and a compared result of the CPU 12 is coincident, the selector 11 outputs a control signal CG for stoppage to a rear-stage control system. As a result, the stopping position, namely, the range of C=0 of a motor 6 is divided into four ranges and the stopping position is determined in one of the divided ranges. Therefore, positioning accuracy is improved four times.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention 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 the motor to be controlled, and pulses of a predetermined frequency according to a command speed pattern are input from a control circuit such as a CPU to a reversible counter as a feed command value. Ru.

This reversible counter receives the command pulse as an input, uses the output pulse of the rotary encoder as a feedback signal, and outputs the deviation thereof to the speed servo amplifier of the motor via the DA converter. In this way, the speed servo amplifier drives the motor using a voltage proportional to the number of pulses of the reversible counter as a speed signal.

During this time, if the deviation of the reversible counter becomes rOJ,
Following this, the speed signal also becomes "o", so the motor automatically stops at the target position.

By the way, the stopping 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, as the resolution of the rotary encoder increases, the number of pulses per revolution of the motor increases accordingly, so it is impossible to respond appropriately unless the capacity of the reversible counter is increased. In addition, it is necessary to increase the resolution of the D-A converter and speed servo amplifier accordingly, which requires design changes to the control system and servo system itself, and each control element becomes expensive, making it difficult to incorporate In relation to the object,
There are limits to practical application.

Purpose of the Invention Therefore, the purpose of the present invention is to improve the resolution of control system elements and feedback system components without increasing their resolution.
The aim is to improve positioning accuracy when the controlled object is stopped.

Solution to the Invention Therefore, the present invention focuses on the two-phase pulses of a rotary encoder, compares the combination state of the two-phase pulses with a pre-specified pulse phase, and calculates the result according to the match state of these comparison results. Then, the stopping position of the controlled object is determined.

In order to realize this, the present invention interposes a stop controller between the reversible counter as the first comparing means and the D-A converter, and 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. Then, the stop control means in the stop controller outputs a control signal for stopping only when the count value of the reversible counter is "0" and the comparison result of the second comparison means matches. Sends to the subsequent control system. As a result, in such a control system, the stop region corresponding to one deviation of the count value is divided by the number of combinations of two-phase pulse outputs, so the control system and servo system can be used as highly accurate ones. Even if it is not configured, the positioning accuracy at the time of stopping will be improved.

Note that if the count value of the reversible counter is other than "0", the stop controller sends the positional deviation of the reversible counter as it is to the next-stage DA converter. therefore,
Control other than when stopping operates in the same way as the conventional digital servo system.

Structure of the Invention FIG. 1 shows a digital servo type high precision positioning device 1 of the present invention. This high-precision positioning device 1 includes a reversible counter 2 as a first comparison means that receives a command value A as one input, a stop controller 3 as a characteristic part of the present invention, a DA converter 4, and A speed servo amplifier 5 and a motor 6 as a rotating member to be controlled are sequentially connected in series.

A speed detector 7 of a speed servo system and a rotary encoder 8 of a digital feedback system are mechanically connected to the motor 6, respectively. This speed detector 7 is a tacho generator or the like, and is connected to a summing point 9 on the input side of the speed servo amplifier 5. Also,
The rotary encoder 8 outputs two-phase pulses B with a phase difference of 90 degrees, for example, in order to detect the rotation direction of the motor 6.
1 and B2, which are 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 the internal configuration of the stop controller 3. As shown in FIG. The stop controller 3 includes a data selector 11 as a stop control means, a magnitude comparator 12 as a second comparison means, and a zero detection circuit 13.

The data selector 11 is constituted by a ROM, etc., and has a plurality of, for example, three "0" patterns, "+1" patterns, and "-1" patterns, as the control signal G at the time of stop.
'' patterns, etc., and selectively outputs one of the patterns according to the comparison result of the magnitude comparator 12. The zero detection circuit 13 also includes a reversible counter 2 and a data selector 11.
, and detects the position where the motor 6 should stop, that is, the count value "0". Furthermore, the magnitude comparator 12 is composed of a CPU, etc.
It is provided to compare the magnitude relationship between the pre-input set value H and the pulse outputs B1 and B2 from the rotary encoder 8, and to designate the selection operation of the data selector 11 according to the result. Note that the exclusive or gate 14 on the input side of the magnitude comparator 12
is provided to align the actual phase order of the pulse outputs B1 and B2.

Effect of the Invention First, an operator inputs a definition of "1.0=2", for example, as a preset value H into one input terminal of the magnitude comparator 12 in advance. In addition, the operator sets a numerical value B of the magnitude as shown in the table below for the four combinations of pulse outputs B1 and B2, and also sets a "0" pattern and a "-1" pattern as the control signal G to the data selector 11. , and "+1" patterns are respectively stored.

First, a command value A is given to one input terminal of the reversible counter 2 from the control circuit side to the control system.

In this initial state, the count value C is not "0", so the value of the count value C remains unchanged at the stop controller 3.
The signal is converted into an analog command signal by the DA converter 4 and sent to the speed servo amplifier 5. Therefore, the speed servo amplifier 5 generates a drive signal E that is proportional to the command signal, thereby determining the rotational speed of the motor 6 to be controlled and causing it to rotate. The rotational speed of the motor 6 is detected by a speed detector 7 and is negatively fed back to a summing point 9 as a speed feed bank signal F.

On the other hand, the rotation amount of the motor 6 is detected by the rotary encoder 8 as the number of pulse outputs B1 and B2 as shown in FIG. is fed back to the input terminal as a subtracted value. In this way, 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, so that from then on, the motor 6 is in a state proportional to the deviation value. It will be controlled.

By the way, when the count value C of the reversible counter 2 becomes "0", that is, when the motor 6 to be controlled is in the stop region shown in FIG. 11, one condition is given for stop control. On the other hand, the magnitude comparator 12 compares a numerical value B of the magnitude based on the combination of pulse outputs B1 and B2 with a set value H, and outputs data corresponding to the comparison result to the data selector 11 as another selection condition. are doing. Therefore, the data selector 11 (H
When -B)>O, a "+1" pattern is output from the control signal G, and when (H-B)<0, a "-1" pattern is output, and when (H-B)=0, a "-1" pattern is output. selectively outputs a “0” pattern.

As a result, as shown in FIG. 3, the stop range of the motor 6 to be controlled, that is, the range of count value C=0, is divided into four,
The stop position of the motor 6 is determined in the stop range after the division. Therefore, the positioning accuracy of the motor 6 in this control system 1 is increased four times compared to the conventional system. Moreover, this actual stopping position can be freely set within the range of 1/4 of the count value C=0 by the numerical value setting G of the set value H.

As already mentioned, the exclusive or gate 14 has rO-1-3 in relation to the setting of numerical value B.
It is provided to correct the change in -2J to the relationship ro-1-2-34, and can be omitted if necessary.

Modifications of the Invention The above embodiment utilizes two-phase pulse outputs B1 and B2 from the rotary encoder 8, but the number of pulse outputs of different phases is not limited to two phases, but may be three or more. Good too. As the number of phases increases in this manner, the number of divisions of the stop area increases accordingly, and a highly accurate stop position can be ensured. Further, the data selector 11 is constituted by a ROM or the like as a general circuit element, but for two-phase pulse outputs B1 and B2 as in the above embodiment,
It can also be realized by simply combining an exclusive OR gate and a pattern generation circuit.

Effects of the Invention In 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 digital control system or the control elements of the feedback system. Since it can be put into practical use by simply adding a stop controller to the system, high positioning accuracy can be achieved at low cost and with only some improvements to conventional equipment.

[Brief explanation of the drawing]

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. ■... High precision positioning device, 2... Reversible counter, 3...
・Stop controller, 4...D-A converter, 5...Speed servo amplifier, 6...Motor, 8...Rotary encoder, 1
1...Data selector, 12...Magnitude comparator, 13...Zero detection circuit. 3. Figure 2 Figure 3

Claims (1)

[Claims] A positioning device comprising a rotary encoder provided on a rotating member and a first comparing means for comparing a command value and an output value of the rotary encoder, and stopping the rotating member in response to a coincidence signal from the first comparing means. , a stop control means having a rotary encoder that generates a plurality of phase-shifted pulse outputs, a stop control means that stores a plurality of control signals and selectively outputs one of them, a prespecified setting value, and the rotary encoder. and a second comparison means for comparing the phases of the plurality of pulse outputs from the stop control means, and when the first comparison means and the second comparison means both output matching signals, the stop control means controls the rotating member. A high-precision positioning device characterized by outputting a control signal for stopping.