JPH08194541A - Position controller - Google Patents

Abstract

PURPOSE: To synchronize data from a position detection means with synchronizing signals and to perform highly accurate position control by correcting the position data of the position detection means based on timer data and outputting the corrected position data to a control means. CONSTITUTION: Receiving the control signals of a speed command or the like from a CNC device main body, a control part 7 sends a motor control command to a servo amplification part 2. The servo amplification part 2 which receives the command flows a current to a servo motor 3, drives the motor 3 and performs the position control by a feed shaft or the like. The position data are detected in a fixed cycle by an encoder 4 as the position detection means and sent to a position data buffer 6. Every time the position data are sent to the buffer 6, a timer 8 is cleared, starts counting and outputs the timer data by the read command of the position data by the control part 7. Based on the data, the position data of the encoder 4 are corrected and the corrected data are outputted from a position data processing part 5 to the control part 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control device for interpolating and outputting a position data signal, and particularly, when the sampling timing of encoder position data is deviated with respect to the synchronization timing in the main system,
Further, the present invention relates to a position control device which interpolates position data for a deviation and outputs the position data at a synchronization timing.

[0002]

2. Description of the Related Art The prior art will be described. FIG. 2 shows C
It is a block diagram which shows one structure of NC apparatus. In the figure, reference numeral 20 denotes a central CNC device body including a computer and the like, and 21, 21, ... Denote a plurality of servo control unit parts connected to the device body 20. .. are a plurality of servo sections provided in each servo control unit section, and servo motors in which encoders 24, 24 ,. Two
, 23, ... Are provided. With these, feedback control of the position servo system such as the feed shaft is performed for each motor. CN that controls by associating a plurality of such feed axes
In order to improve the accuracy of synchronism of all axes in the C device, it is necessary to have a function of reading highly responsive data from the position detecting means or a function of sending a synchronizing signal to the position detecting means and reading the data at that time. Moreover, the position detector and the data transmission system are expensive.

When the position detector and the data transmission system are made inexpensive and stable by a relatively low cycle independent time period data system (for example, serial transmission system), a synchronization signal for position loop processing and a sampling timing signal for encoder position data are provided. Cannot be synchronized, and the accuracy of position control deteriorates. Regarding the lack of synchronization between the position loop processing synchronization signal and the encoder timing data sampling timing signal,
This will be described with reference to FIG. FIG. 3A shows a cycle T transmitted from the CNC device body to each of the plurality of servo control unit units.
2 shows a sync signal. FIG. 3B shows an output signal of an encoder that samples a position that moves with time at a cycle T1, but has a stepped shape as shown in the figure. Further, the sampling values of the encoder at the time of receiving the synchronization signals a2 and a3 are b3 and b6, and the error of the position data due to the synchronization deviation t1 and t2 between the synchronization signal and the sampling timing is different from the actual value shown by the dotted line. Seen in between. This error component deteriorates the accuracy of the position control. Also, in terms of the simultaneity of a plurality of axes, at the timing of a2 shown in FIGS. 3 (a) and 3 (b), one axis has data of the time of Tb2, 2 The axis becomes the data at the time of Tc3, and the data accuracy between the axes becomes uneven.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art. (1) In the position control loop, the data from the position detecting means is synchronized with the synchronizing signal. , Which enables highly accurate position control,
(2) The synchronization between the synchronization signal of the servo control unit and the sampling timing of the encoder output in the servo is realized by interpolation to improve the accuracy of position control at least during the two-axis feed.

[0005]

To achieve the above object, the present invention performs position control by position detecting means for outputting position data in a fixed cycle and position data read in a cycle slower than the fixed cycle. Servo system control means, timer means for starting timing when the position data is output, and outputting timer data when the position data is read by the control means, and position of the position detection means based on the timer data And a position data processing means for correcting the data and outputting the corrected position data to the control means.

[0006]

According to the present invention, by providing the timer means and the position data processing means between the position detecting means and the servo system control means, the timer starts timing when the position detecting means outputs the position data. Then, the time until the position data is read by the control means is obtained. In the position data processing means, from the comparison between the obtained time and the output cycle of the position data, the position data corresponding to the obtained time is obtained based on proportional distribution, and this position data is used as the known position data at the time of starting the timer. to add. As a result, the position data from the position detection means can be corrected to the value at the time of reading by the control means and output.

[0007]

EXAMPLES Examples of the present invention will be described. Figure 1
It is a block diagram which shows the structure of an Example. Note that FIG. 1 shows only one servo control unit section in FIG.
In the figure, reference numeral 1 is a servo control unit which is one of a plurality of units connected to the main body of the CNC device and comprises a position data processing unit 5, a position data buffer 6, a control unit 7 and a timer 8. A servo amplifier unit 2 receives a control command from the control unit 7 and sends a control current to the servo motor 3.
Reference numeral 4 denotes an encoder built in the servo motor, which converts the feed position by the motor into a digital signal at a constant cycle and outputs it to the servo control unit section 1. A buffer 6 stores the position data sent from the encoder. 5
Is a position data processing unit having a function of reading position data from the buffer 6 in response to a sync signal from the main body of the CNC device, reading timer data from the timer 8, correcting the position data, and then sending the data to the main body of the CNC device. A control unit 7 receives a control signal such as a speed command from the main body of the CNC device and sends a motor control command to the servo amplifier unit 2. 8
Is a timer, which is cleared and started each time the buffer 6 receives the position data from the encoder 4, and counts until the position data processing unit 5 reads the timer data by a synchronization signal from the main body of the CNC device.

Next, the operation of the embodiment will be described.
First, the outline will be described with reference to FIG.
The output signal of the encoder which samples the position which moves with time at period T1 is shown. The difference between (c) and (b) is in receiving the synchronization signal a. That is, the times t1 and t2 from when the encoder samples the position data to when the synchronization signal is received are measured. The calculated time t1
From the ratio of the sampling period T1 to the sampling period T1, the position data corresponding to the time t1 is proportionally obtained, and this is added to the position data value b3 to calculate the interpolated position data value B4. The calculated data value matches the value at the intersection of the dotted line indicating the actual value and the timing of the synchronization signal. These processes are mainly performed by the timer 8 and the position data processing unit 5.
When a control signal such as a speed command is received from the CNC device body,
The control unit 7 sends a motor control command to the servo amplifier unit 2.
Upon receiving the motor control command, the servo amplifier unit 2 supplies a current to the servo motor 3 to drive the motor 3 and perform position control by a feed shaft or the like. The position data due to the movement is detected by the encoder 4 at a constant cycle, and the position data buffer 6
Sent to Every time position data is sent to the buffer 6,
The timer 8 is cleared to start time counting, and the timed timer data is read by the position data processing unit 5 with a synchronizing signal from the main body of the CNC device.

The position data processing unit 5 reads the position data from the buffer 6 and the timer data from the timer 8 according to the position signal from the main body of the CNC device. Further, the position data processing unit 5 calculates the position data amount corresponding to the timer data amount based on the proportional distribution based on the ratio of the read timer data and the fixed period in which the position data is detected. By adding the obtained position data to the read position data, the position data detected by the encoder in a constant cycle is corrected to the position data corresponding to the generation of the synchronization signal and then output to the CNC device body. . The main body of the CNC device compares the corrected position data with the target value and continues to control based on a new control signal based on the deviation. By adopting the configuration of the embodiment described so far for each servo control unit section system shown in FIG. 2, it becomes easy to synchronize each servo control unit section with each control end.

[0010]

According to the present invention, the synchronization between the servo control unit section and the servo section (sampling of encoder position data) is realized by interpolation, and at the same time, the position control accuracy between two axes at the time of two-axis feed is improved. Produce an effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a block diagram showing the configuration of a CNC device.

FIG. 3 is a time chart for explaining position data.

[Explanation of symbols]

 1 Servo Control Unit 2 Servo Amplifier 3 Servo Motor 4 Encoder 5 Position Data Processor 6 Position Data Buffer 7 Control 8 Timer 20 CNC Machine Main Body 21 Servo Control Unit 22 Servo Motor 23 Servo Motor 24 Encoder

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[Procedure amendment]

[Submission date] February 3, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G05B 19/05 19/404 21/02 Z 7531-3H (72) Inventor Haruo Omura 1 Asahi-cho, Kariya city, Aichi prefecture 1-chome, Toyota Koki Co., Ltd. (72) Inventor, Koji Hasegawa 1-1-1, Asahi-cho, Kariya city, Aichi prefecture Toyota-Koki Co., Ltd.

Claims (2)

[Claims] 1. A position detecting means for outputting position data at a fixed cycle, a servo control means for reading position data at a cycle slower than the fixed cycle for position control, and a position detecting means for outputting position data. And a timer means for outputting timer data in response to a position data read command from the control means, and correcting the position data of the position detecting means based on the timer data, and controlling the corrected position data by the control. The position control device according to claim 1, further comprising position data processing means for outputting to the means. 2. A plurality of servo control unit sections are connected to a central control section, and each servo control unit section has a plurality of servo control systems consisting of a servo amplifier section, a servomotor and an encoder, and synchronization from the central control section is provided. A central control device for position control based on a signal, wherein each of the plurality of servo control unit sections includes the timer means and position data processing means.