JP2001154719A - Method for interpolating free curve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute efficient processing at a speed corresponding to processing accuracy based on a processing process even when the speed of only a part of a curve is commanded. SOLUTION: A processing program in which a speed command value is described in each block expressing a unit curve obtained by dividing a free curve by a certain unit is inputted and acceleration/deceleration is controlled by using the speed command value of each unit curve as a limit speed. When the speed command value is not described in the block expressing the unit curve, a numerical controller interprets the description of a speed command value commanded by a block expressing a preceding unit curve or a block existing before the interpolation section of the free curve and acceleration/ deceleration is executed by using the speed command value of a previously stored block as a limit speed. Since the free curve is a NURBS curve, the unit curve is a curve formed by specifying only the number of control points of a rank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free curve interpolation method in a numerical control device used for a machine tool, an industrial robot, or the like.

[0002]

2. Description of the Related Art When performing free curve interpolation in a numerical control device, for example, when performing NURBS interpolation, conventionally, as shown in FIG.
A machining program in which the speed command value F10000 is described is input only to the interpolation section start block, and acceleration / deceleration control is performed using the speed command value as a limit speed over the entire curve as shown in FIG. Alternatively, if no speed command value is described, acceleration / deceleration control is performed using the speed command value as a limit speed over the entire curve using a speed command value specified in a block before the NURBS interpolation section.

[0003]

However, in the prior art, since the limit speed is limited to one of the speed command values, the processing accuracy is deteriorated depending on the processing step, but the speed may be increased. In this case, the speed cannot be increased, and as a result, there is a problem that the processing time becomes longer. Therefore, the present invention enables a finer speed control by a speed according to the processing accuracy in the processing step, even at a partially specified speed of the curve,
The purpose is to perform processing efficiently.

[0004]

In order to solve the above-mentioned problems, a free curve interpolation method according to the present invention provides a machining program in which a speed command value is described for each block representing a unit curve obtained by dividing a free curve by a certain unit. The acceleration / deceleration control is performed for each unit curve by using the speed command value as a limit speed. Further, in the invention according to claim 2, when the speed command value is not described in the block representing the unit curve, a command is issued in a block representing a previous unit curve or a block before an interpolation section of the free curve. The numerical control device interprets that a speed command value is described, and performs acceleration / deceleration control using the speed command value in the block stored in advance as a limit speed. Furthermore, in the invention according to claim 3, the free curve is N
A URBS curve, wherein the unit curve is a curve that can be designated by the number of control points of the floor.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a numerical control device that implements the free curve interpolation method of the present invention. This numerical control device is applied to, for example, a control system of various industrial machines such as machine tools and industrial robots, and performs numerical control on a computer basis such as a microprocessor. FIG.
Is comprised of a program input unit 101, a program analysis unit 102, a control unit 103, and an axis control system 110. The control unit 103 includes a function generation processing unit 104
From the command correction unit 105, the axis control system 110
11, a servo motor 112, and a position detector 113. The program input unit 101 is a unit for inputting a machining program described by an operator or the like, and the input machining program is output to the program analysis unit 102. The program analysis unit 102 is used in the case of automatic operation, and analyzes a machining program output by the program input unit 101 to obtain various data such as a position and a speed, and outputs the data to the control unit 103. The function generation processing unit 104 of the control unit 103 generates and outputs a time function of speed from the various types of input data. The command correction unit 105 receiving the command generates a command corrected for each axis based on the time function, and outputs the command to the axis control unit 111 of the axis control system 110. Upon receiving this command, the axis control unit 111
The rotation direction, the rotation speed, and the rotation amount are controlled. The axis control unit 111 performs feedback control based on the position detection signal of the position detector 113.

Next, the procedure for implementing the method of the present invention is described as NUR.
The case where BS interpolation is performed will be described as an example. First, a machining program for NURBS interpolation input to the numerical controller will be described. In the case shown in FIG. 2, since the floor P is 4, one unit curve is formed by the four control points and the weight R. Then, each time one control point and one weight are added, one unit curve is added. Therefore, one control point and one weight are designated for one block, so that the first to fourth blocks are the first unit curves, and the second to fifth blocks are the second unit curves, The third to sixth blocks form the third unit curve. However, regarding the knot K, the knots of the first unit curve are from the first block to the eighth block, and the knots of the second unit curve are from the second block to the ninth block. The blocks up to the block are knots of the third unit curve. Furthermore, each speed command value, for example, F1000, is added to the first block of each unit curve.
When 0, F5000, and F8000 are described, the processing program is NURBS interpolation according to the present invention.

Next, NURB using the above-mentioned machining program
The procedure for executing the S interpolation will be described. The procedure involves the following steps. As shown in FIG. 2, a NURBS interpolation machining program in which a speed command value is described for each block representing each unit curve is input to the numerical controller by the program input unit 101. The input machining program is converted to a program analysis unit 10
2 analyzes and generates a target position for each unit curve, a speed at the target position, a deceleration point other than the target position such as a minimum radius of curvature radius, and data of the speed and the speed command value at the deceleration point. Then, it outputs to the control unit 103. Based on the information output by the program analysis unit 102, the function generation processing unit 104 generates a time function of the speed with the speed command value as the limit speed (FIG. 3), and the command correction unit 105 receiving the function generates the time function. A command corrected for each axis is generated and output to the axis control unit 111 of the axis control system 110. The axis controller 111 receives the input command and the position detector 113.
, The servo motor 112 is rotated by a predetermined amount of rotation in a predetermined rotation direction and a predetermined rotation speed. When the speed command value is not described in the block representing the unit curve of the machining program, for example, when F5000 in FIG. 2 is not described, the program analysis unit 102 determines the speed in the block representing the previous unit curve. Command value F10
000, and the function generation processing unit 104 performs acceleration / deceleration control by generating a time function of speed using the speed command value as a limit speed. Further, for example, when F10000 in FIG. 2 is not described, the program analysis unit 102
Set the speed command value of the block before the RBS interpolation section,
The function generation processing unit 104 generates a time function of speed with the speed command value as a limit speed, and performs acceleration / deceleration control.

[0008]

As described above, according to the present invention, the limit speed can be designated for each unit curve, and the speed can be controlled in accordance with the limit speed. There is an effect that the speed can be controlled and machining can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an apparatus for carrying out a method of the present invention.

FIG. 2 shows a machining program input to an apparatus for implementing the method of the present invention.

FIG. 3 shows an example of a function showing the relationship between time and speed generated by the method of the present invention.

FIG. 4 is a machining program input to an apparatus for implementing a conventional method.

FIG. 5 is an example of a function showing a relationship between time and speed generated by a conventional method.

[Explanation of symbols]

 Reference Signs List 101 program input unit 102 program analysis unit 103 control unit 104 function generation processing unit 105 command correction unit 110 axis control system 111 axis control unit 112 servo motor 113 position detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H269 AB01 AB33 BB05 EE01 EE13 GG01 GG08 PP15 QB17 RB03 RB11

Claims (3)

[Claims] 1. A free-curve interpolation method in a numerical controller, comprising: inputting a machining program in which a speed command value is described for each block representing a unit curve obtained by dividing the free curve by a certain unit; A free curve interpolation method characterized by performing acceleration / deceleration control using a command value as a limit speed. 2. If the speed command value is not described in a block representing the unit curve, a speed command value commanded in a block representing a previous unit curve or a block before an interpolation section of the free curve is described. 2. The free-curve interpolation method according to claim 1, wherein the numerical controller interprets that the speed control has been performed, and performs acceleration / deceleration control using the speed command value in the block stored in advance as a limit speed. 3. The free curve is a NURBS curve,
3. The free curve interpolation method according to claim 1, wherein the unit curve is a curve that can be specified by the number of control points of the rank.