JP2002268751A - Servo controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a servo controller capable of continuing control when the duration of a communication error is short. SOLUTION: In a servo controller for controlling an object to be controlled while mutually transmitting and receiving control data between a CNC device 11 and a servo driver 20 in each preliminarily decided sampling cycle, recovery processing corresponding to the contents of the control data is preliminarily decided, and when any communication error is generated between the CNC device 11 and the servo driver 20, the recovery processing corresponding to the control data at that time is executed so that the control of the object to be controlled can be continued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo control device for controlling a control target while transmitting and receiving control data between a CNC device and a servo driver at predetermined sampling periods. The present invention relates to a servo control device that is less affected by a communication failure (hereinafter, referred to as a “communication error”).

[0002]

2. Description of the Related Art In order to improve the functions and performance of machine tools, robots, etc., not only high-speed and high-performance CNC devices for controlling them, but also real-time by increasing the speed of the interface between the CNC devices and servo drivers. Processing is required.

FIG. 6 is a block diagram of a conventional servo control device. The CNC device 11 and the servo driver 12 are connected by a communication path (line) 14 and a communication path (line) 15. In line 14, a command from the CNC device 11 to the servo driver 12 is transmitted, and
Then, a response from the servo driver 12 to the CNC device 11 is transmitted. The servo driver 12 is a CNC device 11
The servomotor 13 is driven based on the command transmitted from.

FIG. 7 is a diagram showing an operation sequence of a conventional servo control device.

[0005] The CNC device 11 sequentially transmits commands X1, X2, etc. to the servo driver 12 at a predetermined operation cycle (sampling cycle). The servo driver 12 controls the rotation angle of the servo motor 13 based on the received command to operate a control object (not shown) (for example, to move a table to a designated position), and to send the current information to the CNC device 11. Are sequentially transmitted (replyed) as responses R1 and R2.

The CNC device 11 and the servo driver 1
The command and response between the two are, for example, HDLC (High L
Serial communication such as level data link control is employed.

[0007]

In a servo control device employing this type of communication represented by motion control, when a communication error occurs on an interface, the position of a control target operating in real time cannot be controlled. Communication errors are constantly monitored by a cycle check (CRC) method or the like. Then, when a communication error occurs at the time of transmitting the command (command X2 in FIG. 7), the servo driver 12, which has detected that the communication error has occurred,
The motor 13 is stopped, and the fact that a communication error has occurred is set in the response R2 (write) CN.
Transmit to the C device 11.

When the CNC device 11 recognizes that a communication error has occurred based on the response R2, the CNC device 11 executes error handling measures such as disconnection of the power circuit and display of the content of the error, and stops the entire device.

However, once the entire apparatus is stopped due to an instantaneous communication error, work for investigating the cause and recovery work for returning to the operating state are required, and the operating rate of the entire apparatus is reduced. For this reason, serial transfer with reduced wiring and stable communication is often adopted. In addition, measures are taken to prevent the occurrence of communication errors, such as adopting a twisted pair line or a differential transmission line as a communication cable, or adopting an optical cable in a portion having a large amount of electromagnetic induction noise.

However, since these countermeasures are hardware countermeasures, it is possible to reduce the occurrence of communication errors, but once a communication error occurs, it is necessary to stop the operation of the entire apparatus at that time. No.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to provide a servo control device capable of continuing control when the duration of a communication error is short.

[0012]

In order to achieve the above object, the present invention provides a method in which a CN
In the servo control device that controls the control target while mutually transmitting and receiving control data between the C device and the servo driver, recovery processing according to the control content is determined in advance. The control of the control object is continued by executing the recovery process corresponding to the control content of (1).

In this case, the servo driver is provided with the C
A storage unit for storing the control data transmitted from the NC device and a determination unit for determining the content of the stored control data are provided, and the movement to the target position is executed after storing the next target position data. If a communication error occurs during movement control, the movement should be performed with the target position between the target position stored before the communication error failure and the target position stored after the communication error occurred as the target position. Can be.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIG. 1 is a block diagram of a servo control device according to the present invention. The components having the same functions or the same functions as those in FIG. The servo driver 20 includes a storage device 21 and a determination device 22 therein.

The storage device 21 sequentially stores commands transmitted from the CNC device 11 in each sampling cycle. The determining device 22 determines that the command transmitted from the CNC device 11 is
A command including data for controlling the movement of the target position or the speed, which indicates the target position in absolute coordinates (hereinafter, referred to as a “movement command”), initializes the servo driver 20, inquires about the state, Alternatively, it is determined whether the received instruction is another instruction (hereinafter, referred to as a “management instruction”) including data for instructing a change of the operation mode or the like.

Next, the servo driver according to the present invention and C
The operation of the NC device will be described with reference to a flowchart.

FIG. 2 is a flowchart showing the processing of the servo driver.

The servo driver 20 receives a command describing control data transmitted from the CNC device 11 (procedure 501 in FIG. 2) and performs the process of procedure 502. In step 502, it is confirmed whether or not the reception has been performed normally. If the reception has been performed normally, the command is stored (step 503), the processing in step 504 is performed, and the reception has not been performed normally. In this case, after the error content is set in the response (procedure 521), the process of procedure 522 is performed.

In step 504, it is checked whether the received command is a movement command.
05, and if it is not a movement command, that is, if it is a management command, the moving flag is cleared (step 510).
After executing the command (procedure 511), the processing of procedure 512 is performed.

In step 512, it is confirmed that the previous command is not a movement command, and if the previous command is not a movement command, that is, if it is a management command, a response is transmitted (step 50).
8) The process is terminated, and if the previous command is a movement command, the previous command is executed (step 507), and the process of step 508 is performed.

In step 505, it is confirmed whether or not the received movement command is the first movement command. If the received movement command is not the first movement command, the process of step 506 is performed. If it is the first movement command, the moving flag is set. After setting (Step 51
5) The process of step 508 is performed.

In step 506, it is checked whether or not the previous reception was normal. If the previous reception was normally performed, the process of step 507 is performed. Calculate the coordinates of the position (step 51
3) After performing the movement to the temporary position (step 514), the process of step 508 is performed. The coordinates of the tentative position are calculated as an intermediate position between the stored target position two times before and the target position stored this time.

In step 522, it is confirmed whether or not the user is moving. If the user is moving, the process of step 523 is performed. If the user is not moving, the process of step 508 is performed.

In step 523, it is checked whether or not the previous reception was abnormal. If the previous reception was normal, the process of step 507 is performed. If the previous reception was also abnormal, an alarm is displayed. And stop the operation.

FIG. 3 is a flowchart showing the processing of the CNC device.

First, the CNC device 11 checks whether it is the first command after the power is turned on (procedure 400), and if it is the first command after the power is turned on, transmits the command (step 402) and performs processing. Is ended, and if it is not the first command, the process of step 401 is performed.

In step 401, referring to the response transmitted from the servo driver 12, if the previous command has been received by the servo driver 12, the processing of step 402 is performed.
If the previous command has not been transmitted to the servo driver 12 due to a communication error, the process of step 403 is performed.

In step 403, it is checked whether the user is moving, and if the user is moving, the process of step 404 is performed.
If not moving, re-send the command (step 405)
The process ends.

In step 404, it is confirmed whether or not the last command is the first or last command of the movement. If the last command is not the first or last command of the movement, the process of step 402 is performed. In the case of, the process of step 405 is performed.

FIG. 4 is a diagram showing an operation sequence of the present invention. FIG. 4A shows a case where a command to be transmitted is a movement command.
(B) shows a case where the command to be transmitted is a management command.

As described with reference to FIGS. 2 and 3, when the command to be transmitted is a management command, the servo driver 20
Executes the command immediately. When a communication error has occurred (command C2 in the figure), the servo driver 20 describes in the response A2 that the communication error has occurred, and the CNC device 1
Send to 1. The CNC device 11 recognizes from the response A2 that there has been a communication error, and transmits the command C2 again in the next sampling cycle so as not to affect the control target (not moving). That is, when the operation of the control target is not directly affected, the command is transmitted again in the next sampling cycle to prevent the system from stopping.

If the transmitted command is a movement command, the servo driver 20 executes the previous command after receiving the next movement command. When a communication error occurs (command P3 in the figure), the CNC device 11 transmits the next command without transmitting the command that caused the communication error again. Then, the servo driver 20 executes the movement by regarding the average value of the target position P2 two times before and the current target position P4 as the previous target position P3 that could not be received due to a communication error. Therefore, the control is not interrupted and the real-time control is not impaired.

FIG. 5 is a diagram for explaining an error when a communication error occurs. The vertical axis represents the position of absolute coordinates to be sequentially instructed, and the horizontal axis represents the sampling time.

The CNC device 11 sets a target position (P) that must reach each sampling time (T1 to T8) from the speed / acceleration set for the control target.
1 to P8) are calculated and sequentially transmitted to the servo driver 20.

In the above case, the tentative position calculated as the average value of the target position P2 two times before and the current target position P4 based on the movement command is shifted from the target position P3 described in the previous movement command. In the next sampling period, since the positioning is performed at the commanded target position, there is no practical problem.

In the present invention, the execution of the command from the CNC device is delayed by one sampling cycle, but this does not pose any problem in the operation of the servo driver for executing the feedback control.

Also, in this embodiment, the movement command and the management command are distinguished on the CNC device side, but the movement command and the management command are determined on the servo driver side (for example, there is a change in the commanded target position. The case may be determined as a movement command, etc.).

The error recovery system of the present invention can be applied not only to the communication configuration of the HDLC system shown in the embodiment but also to an interface between a CNC device and a servo driver by another communication system.

[0040]

As described above, according to the present invention,
Even in a system that performs operation control in real time, a communication error that occurs suddenly can be recovered, so that system stability and operation rate can be improved without downtime of the system.

[Brief description of the drawings]

FIG. 1 is a block diagram of a servo control device according to the present invention.

FIG. 2 is a flowchart showing processing of a servo driver according to the present invention.

FIG. 3 is a flowchart showing a process of the CNC device according to the present invention.

FIG. 4 is an operation sequence diagram of the servo control device according to the present invention.

FIG. 5 is a diagram for explaining an error when a communication error occurs.

FIG. 6 is a block diagram of a conventional servo control device.

FIG. 7 is a diagram showing an operation sequence of a conventional servo control device.

[Explanation of symbols]

 11 CNC device 20 Servo driver

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H209 AA06 AA07 BB07 CC13 DD11 FF01 HH13 5H269 BB11 KK05 MM04 NN14 PP02 PP17 5H303 AA01 AA10 CC03 DD01 EE08 FF07 GG21 HH07

Claims (2)

[Claims] 1. The method according to claim 1, wherein CN is performed every predetermined sampling period.
In a servo control device that controls a controlled object while mutually transmitting and receiving control data between the C device and the servo driver, recovery processing according to the control content is determined in advance. A servo control device that continues the control of the control target by executing the recovery process corresponding to the control content of (1). 2. A storage means for storing the control data transmitted from the CNC device in the servo driver;
A determination means for determining the content of the stored control data is provided, and the movement to the target position is determined to be executed after storing the next target position data, and when a communication failure occurs during the movement control, 2. The servo control device according to claim 1, wherein the movement is performed with a target position between a target position stored before the occurrence of the communication failure and a target position stored after the occurrence of the communication failure as a target position.