JPH02193584A - Servo controller - Google Patents

Abstract

PURPOSE:To preserve various types of sampling immediately before at the time of abnormal stop in memory means and to shorten repairing time by checking the content by providing memory means for storing sampled latest values for a positional deviation, speed, current, etc., in predetermined number backup memory. CONSTITUTION:Various values such as a positional deviation epsilonp, a speed command VCMD, a speed feedback value VFBK, a current command ICMD and a current feedback value IFBK are stored in a backup RAM 18 at each sampling time at the time of normal operation, and sequentially updated with latest values. If any malfunction is detected by abnormal time stop means 26 and an operation is stopped, data epsilonp, VCMD, VFBK, ICMD, IPBK sampled immediately before are preserved and retained in the backup RAM 18. Accordingly, the data are read by a CPU 11 to know the behavior of a servo immediately before the abnormal stop.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention is a servo control device! The present invention relates to a device suitable for application to a numerical control device.

"Prior Art" A servo control device generally has a function of stopping its operation in the event of an abnormality. These abnormality stopping means determine that an abnormality occurs when position deviation, speed, current, etc. meet predetermined thresholds, and stop the operation.They also latch the instantaneous abnormality content and detect excessive error or overspeed. .

Or, it used a lamp to indicate overcurrent, etc.

``Problem to be solved by the invention'' However, since the servo control device forms a closed feedback loop, for example, even if it stops due to an excessive error during operation, it does not necessarily mean that there is an abnormality in the position loop system. First, there was a problem in that it was difficult to determine the true cause of servo abnormalities.

The present invention has been made to solve the above problems, and its purpose is to facilitate investigation of the true cause of a malfunction when it occurs, and to reduce the repair time required for recovery.
T R (Mean Time to Repair)
The object of the present invention is to provide a servo control device that can shorten the time.

"Means for Solving the Problem" In order to achieve the above object, the present invention provides a position loop,
Excessive position N deviation, which has a velocity loop and a current loop feedback loop, and indicates a tracking error for the position command;
In a servo control device having an abnormality stopping means that detects excessive speed or excessive current and stops the operation, the position deviation, speed, and current of each feedback loose are sampled at predetermined time intervals. a sampling means, a storage means for storing each of the latest samples sampled a predetermined number of times in a backup memory, a display means capable of displaying the contents stored in the storage means, and the operation is stopped by the abnormality stopping means. A servo control device is provided, comprising: display command means for outputting a command to cause the display means to display the contents of the backup memory after the content of the backup memory is displayed.

"Operation" In the servo control device configured as described above, the position deviation, speed deviation, and current deviation are constantly monitored during normal operation, and are constantly updated in the storage means. At the time of abnormal stop, since the operation stops, the latest predetermined number of operations are stored in the storage means. Therefore, the display command means causes the display means to display the content stored in the storage means,
By examining the contents, it is possible to know the operation immediately before the abnormal stop.

"Example" Embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing the hardware configuration of the servo control device according to the embodiment. The control main body consists of a computer 1, a CPU II, a memory 12. Current value counter 13.
D/A converter 14. An A/D converter 15 is provided. The memory 12 is a ROM16. A backup RA equipped with 17 RAMs, some of which retain their contents even when the power is turned off.
It constitutes the M area 18. Further, a CRT display device 7 and a keyboard 8 are connected to the CPU II via an interface circuit 19. The CRT display device 7 constitutes a display means capable of displaying the contents stored in the RAM 17 and the backup RAM 18, and the keyboard 8 constitutes a display command means for outputting a command to display the contents of the backup RAM 18 on the CRT display device 7. The output of the D/A converter 14 is connected to a current amplifier 2, and the current amplifier 2 drives the servo motor 3 according to the output signal level of the D/A converter 14.

A non-commutator motor is used as the servo motor 3, and PWM
The control controls the drive current and the torque. The drive current of the servo motor 3 is detected by the current detector 5, and is input to the A/D converter 15 and monitored. Further, a pulse encoder 4 is attached to the servo motor 3 to detect its position. The output of the pulse encoder 4 is connected to a current value counter 13 via a waveform shaping and direction determining circuit 6.

In this embodiment, the servo control constitutes a digital servo realized by digital processing within the computer 1.

FIG. 1 is a block diagram of a servo control device showing the functions realized by the processing.

The current position feedback value Py read from the current value counter 13, which is adjusted by the signal from the pulse encoder 4, is matched with the target value, and the position deviation ε2 is calculated and stored in the RAM 17. The position deviation ε is multiplied by 8 by the amplifying means 21, and the speed command ■c11. is calculated. On the other hand, the current position feedback value pvm from the pulse encoder 4 is differentiated by the differentiator 25, and the velocity feedback value VyB is calculated. The speed command vcIID and the speed feedback value ■ are combined to calculate the speed deviation ε, and the amplification means 22 calculates the speed deviation ε! The current command Iago is calculated by multiplying the current command Iago. The current command I e++a is passed through the A/D converter 15 to the amplification means 2.
The current deviation ε! is combined with the current feedback values ■, □ read through 4. is calculated and stored in the RAM 17. The current deviation ε1 is multiplied by three by the amplifying means 23 and sent to the current amplifier 2 via the D/A converter 14, and the servo motor 3 is driven.

As mentioned above, the servo control system is composed of three feedback loops: a position loop, a velocity loop, and a current loop. Since lower level feedback loops require higher responsiveness, as shown in Figure 3,
For example, the current loop is taps, the velocity loop is several times that, tlls, and the position loop is several times that, t3.
Data sampling is performed synchronously at time intervals of 11B, and respective feedback loose processing is performed.

In each process, position deviation ε, speed feedback value ■2□, or current feedback value ■2. ．． When exceeds a predetermined threshold value, the abnormality stop means 26 stops driving the motor 3 and stops the control operation.

In this embodiment, in addition to the above processing, the positional deviation ε,

Speed command V (11101 Speed feedback value Vym*
+ Current control work. l, current feedback value I21. The storage means 31 to 35 perform a process of storing the data in the backup RAM 181. This storage process is performed at each sampling time for each time interval of t1μs, tlps, and t, (3). Backup RA
In M18, each data is stored a predetermined number of times, for example, t 5
An area that can store data sampled during 118 is set as a memory buffer.

The operation will be explained. During normal operation, normal digital servo processing is executed and the servo motor 3 is controlled in a closed loop with three feedback loops. At this time, position deviation ε□ speed command V6N. , to the velocity feedback value VFI.

Current command I aw. and current feedback value■2.1
are stored in a memory buffer in the backup RAM 18 at each sampling time, and are successively updated with the latest values.

When some abnormality is detected by the abnormality stop means 26 and the operation is stopped, each of the above data ε2. V6NO+ VF
llt+I CNl1+I FIK is saved and left in the backup RAM 18. Therefore, CPU11
By reading these data, it is possible to know the behavior of the servo immediately before the abnormal stop.

For example, if an abnormality such as biting occurs in the mechanical system, and this causes a servo abnormality, first data regarding the position (in this example, the position deviation ε,
) shows an abnormal value, and then the data related to speed (speed feedback value Vrag) and the data related to current (current feedback value IPBK> If a servo error occurs, as shown in Figure 5,
First, the speed data shows abnormal values, then
This spreads one after another to data related to current and position.

Therefore, by checking the timing at which each data shows an abnormal value immediately before stopping, the true cause of the servo abnormality can be easily investigated.

"Effects of the Invention" Since the present invention is configured as described above and is equipped with a means for storing various data during servo control in a backup memory, it is possible to easily investigate the cause of the abnormality when a malfunction occurs. Mean time to repair (MTTR)
This has the effect of making it extremely short.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a block diagram showing the configuration of a servo control device, FIG. 2 is a block diagram showing the hardware configuration, FIG. 3 is a timing diagram showing the operation, and FIGS. FIG. 5 is a timing diagram showing the operation when an abnormality occurs. 123. computer, 200. Current amplifier 11. Servo motor, 411. Pulse encoder, 51. , current detector, 7., CRT display device 3° position (display means), 811. Keyboard (display command means) 12, Memory, 17, RAM. 18. Figure 18: Backup RAM (backup memory). Figure Figure

Claims (1)

[Claims] It has each feedback loop of a position loop, a speed loop, and a current loop, and stops the operation by detecting an excessive position deviation, excessive speed, or excessive current, etc., which indicates a tracking error with respect to a position command. In the servo control device, the servo control device has a means for stopping at the time of an abnormality, and a sampling means for sampling each value of the position deviation, speed, and current of each of the feedback loops at each predetermined time, and a sampling means for sampling each of the values of the position deviation, speed, and current of each of the feedback loops at predetermined time intervals, and each of the latest sampled values. storage means for storing the number of times in a backup memory; display means capable of displaying the contents stored in the storage means; and display means for displaying the contents of the backup memory on the display means after the operation is stopped by the abnormality stopping means. A servo control device comprising: display command means for outputting a command to