JPS62237509A - Forming method for control command data for numerical control - Google Patents

Abstract

PURPOSE:To prevent a machine from being charged with overload due to unnatural acceleration/deceleration by previously inspecting whether a control command value is suitable or not, and when the command value is unsuitable, correcting the command value. CONSTITUTION:A numerical control device 1 executes the inputs, storage and output of control data, etc., for respective axes 6X, 6Y in every optional interval clock. Variation operating parts 10X, 10Y calculate the differences, i.e. variations, between acceleration values obtained by acceleration operating parts 9X, 9Y before and after each interval clock. Correct value operating parts 11X, 11Y calculate control command values corrected based on the variations and supply the calculated values to the device 1. Consequently, the distribution of pulses can be suitably executed and the machine side can be prevented from being charged with overload due to unnatural acceleration/deceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for generating control command data in numerical control for machine tools, robots, etc.

[Conventional technology]

Conventional numerical control is performed using control command values representing position and speed.

[Problem that the invention seeks to solve]

For example, conventional speed control is performed by maintaining or changing pulse distribution in accordance with the current position of the controlled object at a preselected control gain, but this pulse distribution is appropriate from the machine's perspective. Whether or not this is the case has not been considered.

However, if the pulse distribution described above is inappropriate, vibrations may occur in the machine or response characteristics may deteriorate, making it impossible to achieve high-speed, high-precision positioning control.

[Means for solving problems]

Therefore, in the present invention, it is checked in advance whether the control command value for speed control is appropriate, and if the command value is inappropriate, a process is performed to correct the control command value, and It was developed with the purpose of providing a method for forming control command values, and its structure is to calculate acceleration for each arbitrarily settable interval clock from control command values (original command values) representing position and velocity. The amount of change in acceleration for each interval clock is calculated, and in order to reduce the amount of change in acceleration, the acceleration for each interval clock is set to an original command value that includes the acceleration 2 hours based on the a command value or the original command value. Replace the original control command value with a constant acceleration including zero acceleration for each interval lock or an acceleration that changes at the same rate in the same direction, which can be separately set arbitrarily within the allowable value for . It is characterized in that it is corrected and used as control command data.

〔Example〕

Next, examples of the method of the present invention will be described.

Reference numeral 1 is a numerical control device mainly composed of a computer or the like, and inputs, stores, and outputs control data for each of the controlled axes 6X, 6Y, etc. at each arbitrarily settable interval lock. It looks like this.

Reference numeral 2 denotes an interface unit for outputting control data as a pulse signal, that is, a control command value, in which the command value is shaped into a command pulse train and supplied to the differential counters 3X and 3Y of each axis. In these counters 3x and 3Y, the output is D/
The signal is converted into A and supplied to the servo drive circuits 4X and 4Y as a speed command.

Servo drive circuits 4X and 4Y drive servo motors 5X and 5Y for each axis. The output of the motors 5X and 5Y for each axis is transmitted to the X-axis table 6X and
Movement of table 6Y on the Y axis.

Acts as a stop driving source.

The motors 5X and 5Y for each axis in L are provided with tacho generators 7X and 7Y and pulse generators 8X and 8Y on each axis, and a speed feedback signal Vx for each axis.
, Vy and position feedback signals Px, Py are detected and fed back as feedback data every interval clock and taroch.

The above 1 to 8X and 8Y constitute an example of a control system that executes a conventional numerical control method using feedback control for the two axes X and Y.

In the present invention, in the conventional control system described above, acceleration is determined for each axis at the same interval lock from the control command value for each axis.

9X and 9Y are calculation units and IOs for determining this acceleration.
X and IOY are change calculation units that calculate the difference between the previous and subsequent acceleration values for each interval clock determined by the acceleration calculation unit, that is, the amount of change.9 In the present invention, the amount of change for each interval clock is reduced. Therefore, for example, the interval clock is made smaller and the amount of change in acceleration is made smaller, and the position and velocity control command values are calculated using the smaller interval clock and the reduced amount of change in acceleration.

11X and IIY are correction value calculation units for calculating the control command value to be corrected.

Here, the correction values in the calculation units LIX and ILY are as follows.

The original command values for position and velocity are within the allowable range. Furthermore, the reduced interval clock is also subdivided within the allowable time based on the original command value.

〔Effect of the invention〕

In this way, the acceleration at each appropriate interval clock is calculated from the original position and velocity command values.

If we calculate a new acceleration for each interval clock within the allowable range so that this change in acceleration is small, and then form a new command value to correct the original command value based on this and supply it, it will cause an unreasonable addition to one machine. No burden due to deceleration.

Incidentally, in the past, changes in acceleration caused by control command values, so to speak, fluctuations in acceleration have not been considered at all. This acceleration fluctuation causes vibration of the machine and a decrease in positioning accuracy.

This is a major reason why high-speed, high-precision numerical control is difficult to achieve.

Furthermore, since changes in acceleration can be prevented from increasing with each small interval clock, the responsiveness of speed changes is improved.

In the above embodiment, the newly generated control command value is
Deviation counter for each axis 3X, 3Y servo drive circuit 4X
, 4Y are compared with the respective feedback data, so the embodiment is a feedback loop control system, but even if the present invention is applied to an open loop control system, the same effect as the above embodiment can be obtained.

Furthermore, when implementing the method of the present invention, the gain parameter of the entire control system or the gain parameter of the servo drive circuit may be corrected every interval clock. In this way, control efficiency can be further increased.

Furthermore, the acceleration for each interval clock newly calculated based on the original command value may be used as the control command value, and this may be supplied as is.

The present invention is as described above, and is extremely useful as a numerical control method for machine tools, robots, etc.

[Brief explanation of drawings]

The figure is a block diagram of an example of a control system that implements the method of the present invention. 1... Numerical control device, 2... Interface section,
3X, 3Y...deviation counter, 4X, 4Y...servo drive circuit, 5X, 5Y...servo motor, 6X
. 6Y... Controlled object, 7X, 7Y... Tacho generator, 8X, 8Y... Pulse generator, 9X, 9Y
... Acceleration calculation section, IOX, IOY... Change amount calculation section, IIX. lIY...Correction value calculation section

Claims (1)

[Claims] 1. Obtain the acceleration for each interval clock that can be set arbitrarily from the control command value (original command value) representing the position and velocity, calculate the amount of change in acceleration for each interval clock, and calculate the change in the acceleration for each interval clock. In order to reduce the amount of change, the acceleration for each interval clock can be set separately as desired within the range of allowable values for the original command value, including the original command value or the acceleration and time based on the original command value. A control command characterized in that the original control command value is corrected based on this acceleration, and this is used as control command data. How the data is generated. 2. To reduce the amount of change in acceleration by calculating the amount of change in acceleration for each interval clock by finding the acceleration for each interval clock that can be arbitrarily set from the control command value (original command value) representing position and speed. , the acceleration for each interval clock is the original command value or the acceleration based on the original command value, including zero acceleration for each interval lock that can be separately set arbitrarily within the range of allowable values for the original command value including time. A method for generating control command data, characterized in that the acceleration is replaced with a constant acceleration or an acceleration that changes at the same rate in the same direction, and this acceleration is used as control command data. 3. A method for generating control command data according to claim 1 or 2, wherein the control command data is corrected by comparison with feedback data corresponding to a command value fed back from the controlled object side. 4. The method for generating control command data according to any one of claims 1 to 3, wherein the control command value includes a gain parameter for each interval clock that can be arbitrarily set for the control system or the servo drive circuit.