JPH0437907A - Smoothing acceleration/deceleration system - Google Patents

Abstract

PURPOSE:To improve the torque fluctuation produced at the motor side in order to reduce the vibration of an equipment at the time of accelerating/ decelerating and to shorten the cycle time by using a 2nd timer interruption to attain the linear approximation for the output of the normally stepped mode velocity command voltage. CONSTITUTION:A CPU 4 reads the distribution/feedback processing out of a memory 1 and carries out them by a 1st timer interruption. At the same time, a velocity command is outputted to a D/A converter 6 based on the fetch/ distribution commands of a position counter 5. The analog output of the converter 6 drives an external actuator and a servo motor 8 via a servo amplifier 7, and the detection output of an encoder 9 is inputted to the counter 5 and the amplifier 7. Under the acceleration/deceleration processing, the smoothing acceleration/deceleration processing is carried out by a 2nd timer interruption so that the linear approximation is applied to the output value which is changed in steps and applied to the converter 6 by the 1st timer interruption. Thus it is possible to improve the torque fluctuation produced at the side of the motor 8. Then the vibration of an equipment can be reduced at the acceleration/ deceleration and the cycle time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a smoothing acceleration/deceleration method in numerical control of NC (numerical control) equipment. Specifically, the present invention relates to a smoothing acceleration/deceleration method that uses timer interrupts to improve torque fluctuations occurring on the motor side, reduce vibrations during acceleration/deceleration, and shorten cycle time.

<Prior Art> Conventionally, in numerical control of an NC device, it is known that when software servo control is performed, the performance of the servo control section is influenced by the distribution period.

FIG. 6 is an explanatory diagram of temporal changes in the speed command during acceleration.

In this diagram, the distribution cycle is expressed as ΔT (ms) in the current NC equipment.
Then, the speed during acceleration and deceleration similarly changes at 8T. Therefore, depending on the value of 8T, the speed command during acceleration and deceleration becomes step-like, and the influence on motor torque fluctuation becomes large.

Generally, this solution is achieved by increasing the time constant.
Countermeasure 1 can be achieved by reducing the step-like voltage change. However, with the recent demand for higher speeds such as shorter cycle times, the time constant has tended to be smaller, and its influence on the motor torque fluctuations cannot be ignored in inverse proportion to its value.

Therefore, the current challenge is to shorten the distribution cycle, but solving this requires faster hardware.
The situation is difficult in terms of both cost and technology.

(Problems to be Solved by the Invention) Therefore, it is necessary to reduce the influence on motor torque fluctuations by reducing speed fluctuations during acceleration and deceleration. Therefore, in a constant speed state, there is almost no command speed fluctuation and a distribution period of 8T is sufficient, but this problem is solved by subdividing the speed command voltage during acceleration and deceleration.

As a result, the smoothing acceleration/deceleration method, which does not require high-speed hardware and is superior in terms of cost and technology, improves torque fluctuations generated on the motor side, reduces vibration during acceleration/deceleration, and shortens cycle time. It is intended to.

(Means for Solving the Problems) In order to achieve the above object, the smoothing acceleration/deceleration method of the present invention includes an interrupt controller (first and second timers that issue interrupt requests to two at predetermined intervals; In an NC device having a software servo configuration, comprising a CPIJ that reads and executes distribution and feedback processing from a memory in response to a first timer interrupt, and means for giving a distribution speed command processed by the CPU, the second timer interrupt the second timer interrupt; A smoothing acceleration/deceleration method is provided, which includes means for performing linear approximation processing of the speed command voltage using the first timer interrupt.

Furthermore, it is effectively provided by the smoothing acceleration/deceleration method, which includes means for performing an integral calculation on the speed command voltage determined for each distribution period within the second timer interrupt processing time.

(Function) The smoothing acceleration/deceleration method of the present invention uses two timer interrupts and enables linear approximation of the normal step-like speed command voltage output. Use the idle time of the timer interrupt processing time. This processing time is set to take a value slightly smaller than the idle time of the distribution processing of the first timer. During this time, output processing of the speed command voltage is executed.

As a result, the step-like speed command voltage during acceleration/deceleration is divided into smaller parts, which improves the torque fluctuations generated on the motor side.The time constant during acceleration/deceleration is reduced, which reduces the vibration of the equipment that occurs during the cycle. This can shorten the time.

(Example) An example of the present invention will be specifically described below with reference to the drawings.

FIG. 7 is a diagram showing changes over time in the status of normal distribution execution processing under NC numerical control. This distribution is realized by execution processing every time (distribution cycle) Δτ using a timer interrupt. The interval between timer interrupt processing is 8T°. Here, we decided to subdivide the step-like speed command voltage during acceleration/deceleration, and focused on using a second timer interrupt in addition to the first timer every T.

For the speed command voltage value ΔDn determined for each distribution process,
Actual output of the speed command voltage is realized by the second timer interrupt process, and if the amount of change is ΔD, the amount of change is given as follows.

ΔD=K·ΔDn Here, the coefficient ΔD in the above equation is integrated and outputted as a speed command voltage value within the second timer interrupt processing. FIG. 1 is an explanatory diagram to help understand these, and shows how the speed command voltage changes over time during acceleration using the smoothing acceleration/deceleration method.

Here, K is C generated when outputting as speed command voltage.
This is a coefficient that takes into consideration the delay of the R acid component, etc., and the value between 61 and 61 is given by the following equation for oven loop control.

N+1 N; ΔT/Δt Since the second timer interrupt processing time Δt′ uses the idle time of T′ for the first timer interrupt processing time, the following relational expression holds true.

8T−ΔT >N・Δt” The actual processing situation is shown in the time chart showing timer interrupt processing in Figure 2.In other words, the horizontal axis is the elapsed time, and the first The second timer interrupt process is executed every ΔL from the timer interrupt to the end of the distribution process.This processing time Δt° takes a value slightly smaller than the idle time of the first timer's distribution process. During this time, output processing of the speed command voltage is executed.

Figure 3 shows N which realizes the smoothing acceleration/deceleration method of the present invention.
FIG. 2 is a block diagram showing an example of a C device.

This NC device constitutes a distribution and position feedback processing system as a software servo, so at least the memory, timer 2, interrupt controller 3, CPU 4,
The position counter 5 and the D/A converter 6 have the block configuration shown in the figure.

Here, the timer 2 has a first timer (ioms) and a second timer (1S) capable of outputting at intervals, and issues an interrupt request to the interrupt controller 3 at regular time intervals.

At the same time as the interrupt controller 3 receives the interrupt, the interrupt controller 3
Requests interrupt processing.

The CPU 4 reads and executes the distribution and feedback processing from the memory 1 in response to the interruption of the first timer. At this time, a speed command is output to the D/A converter 6 based on the acquisition and distribution command of the position counter 5. Furthermore, the analog output of the D/A converter 6 is output to the servo amplifier 7.
The external actuator and servo motor 8 are driven through the servo motor 8.

The detection output of the encoder 9 is input to the position counter 5 and the servo amplifier 7.

When acceleration/deceleration processing starts, a second timer interrupt causes a process to linearly approximate the output value (ADn) to the D/A converter 6, which changes stepwise in the first timer interrupt, that is, A.
Smoothing acceleration/deceleration processing corresponding to the integral of Dn is performed.

In such a configuration, the operation of the smoothing acceleration/deceleration method will be explained using the flowchart shown in FIG. Same figure (
1) is a flowchart regarding the output part of the D/A converter 6 of the feedback process executed by the first timer interrupt.

D of the feedback process executed by the first timer interrupt
/ Regarding the A converter 6 output part.

First, in the conventional acceleration/deceleration processing part (which is performed in a separate process from DACOUTLIB), when processing is being performed during acceleration/deceleration, set the smoothing enable flag.
Otherwise, set the smoothing disabled flag.

That is, in a stopped state or a constant speed state, there is little speed variation, so there is no need to perform smoothing processing, and this switching is automatically performed using a flag.

Therefore, the DACOUT LIB determines whether smoothing acceleration/deceleration processing is enabled or not, and when it is not.
The first timer interrupt can be obtained from conventional processing. The value of DS is set as is in Ds, and when it is valid, the current DS is used as is.

(2) Calculate the difference between the target speed value Do and the current speed value Ds and set it in ADn.

Here, if smoothing is disabled in the calculation of ■, D, )=
Ds, ΔDn=O, and no subdivided output is performed.

■ ADn obtained in ■ is multiplied by the coefficient K, and A
Set to D (speed command voltage change amount).

■ Add ΔD to Ds and set it to Ds.

■ D/A converter 61\output.

Here, when smoothing is enabled, the first output is performed by subdivision, and when smoothing is disabled, output is not subdivided (equal to the value of Do).

During the above DACO1JT LIB processing, DAOTASK
interrupts are prohibited.

Furthermore, after the processing is completed, the DAOTASK performs output processing to the D/A converter executed by the second timer interrupt (1S), and Ds is set to Ds+ΔD and output.

When the ΔD obtained by multiplying the coefficient is added to the number of times requested by the second timer interrupt, the value of Ds becomes the value of Do plus exactly ΔDn, that is, Ds=D.)
+ΔDn, which subdivides the intermediate value of the step-like change of the first timer interrupt shown in Fig. 1, and the increase in the actual movement command (area of speed ■ with respect to time t)
are the same, and a smooth change is realized.

FIG. 5(1) is a diagram showing the time change of the speed command during acceleration/deceleration according to the present invention, and shows a state close to linear approximation.

Figure (2) shows the time characteristics of torque for Figure (1), and similarly, the torque fluctuations are extremely small.

On the other hand, Fig. 6 is a diagram showing the time change of the speed command during conventional acceleration/deceleration, and Fig. 6 is a diagram showing the time characteristic of the torque for (1) in the same figure, and shows the time change of the speed command and It is shown that the torque fluctuation is large.As a result, the effect of smoothing the speed command during acceleration/deceleration by the smoothing acceleration/deceleration method of the present invention was confirmed.

(Effects of the Invention) According to the smoothing acceleration/deceleration method of the present invention, by using the second timer interrupt and making it possible to linearly approximate the normal step-like speed command voltage output, Torque fluctuation has been improved.

Furthermore, it has the effect of reducing the vibration of equipment that conventionally occurs due to the reduction of the time constant during acceleration and deceleration, and shortening cycle time.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the time change of the speed command during acceleration in the smoothing acceleration/deceleration method of the present invention, Fig. 2 is a time chart showing the timer interrupt processing in the present invention, and Fig. 3 is the smoothing acceleration/deceleration method of the present invention. FIG. 4 is a block diagram of the NC device that implements the method, FIG. 4 is a flowchart, FIG. Figure 6 is a diagram showing the temporal change of the speed command during conventional acceleration/deceleration, Figure (2) is a diagram showing the torque time characteristic for Figure (1), Figure 7 is a time chart showing conventional timer interrupt processing. 1: Memory, 2: Timer 3: Interrupt controller 4: Central processing unit (CPU) 5: Position counter, 6: D/A converter 7: Servo amplifier, 8: Motor 9; Encoder 1st section Diagram NC fold 17゛Lock view 1 friend L--1---------- Figure diagram Kuku diagram Figure timer interrupt

Claims (2)

[Claims] (1) First and second timers that issue interrupt requests to the interrupt controller at predetermined intervals; a CPU that reads and executes distribution and feedback processing from memory in response to the first timer interrupt; N of a software servo arrangement consisting of means for providing a processed dispensing speed command;
In the C device, the second timer interrupt processing is selected during the idle time of the first timer interrupt processing time, and the processing time is given a value slightly smaller than the idle time of the first timer distribution processing. and means for performing linear approximation processing of the speed command voltage by the first timer interrupt using the second timer interrupt. (2) The smoothing acceleration/deceleration method according to claim 1, further comprising means for performing an integral calculation on the speed command voltage determined for each distribution period within the second timer interrupt processing time.