JP2001034314A - Numerical controller for parallel mechanism machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a locus error and to improve the processing precision by converting Cartesian coordinates representing the position and posture of a movable member into the length of each leg after an acceleration and deceleration processing and making a blade edge position calculated back from the length of each leg after the acceleration and deceleration processing exist on a command value given by the Cartesian coordinates system all the time. SOLUTION: The interpolation coordinates (X, Y, Z, A, B and C) for every function generation period of a movable member outputted from a function generating part 2 is converted by an acceleration and deceleration processing part 3 so that the speed of each component of Cartesian coordinates can smoothly be changed and outputted as Cartesian coordinates (X', Y', Z', A', B' and C') after acceleration and deceleration processing. An inverse mechanism converting part 4 converts the Cartesian coordinates (X', Y', Z', A', B' and C') after acceleration and deceleration processing into the lengths (L1 to L6) of each leg after the acceleration and deceleration processing. Then, a driving device controlling part 5 drives and controls the driving device on the basis of the lengths (L1 to L6) of each leg after the acceleration and deceleration processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a numerical control device for numerically controlling a parallel mechanism machine tool.

[0002]

2. Description of the Related Art Generally, in a numerical control device for a machine tool to which a parallel mechanism is applied, a plurality of fulcrums provided on a movable member are moved in accordance with a command given in a rectangular coordinate system (hereinafter referred to as a Cartesian coordinate system). Control the position and orientation of the movable member. Hereinafter, an example of such a control operation will be described for a machine tool to which the parallel mechanism shown in FIG. 2 is applied.

In the parallel mechanism machine tool shown in FIG. 2, six fulcrums 23 provided around a fixed member 21 and six fulcrums 24 provided around a movable member 22 are connected by legs 25, respectively. The distance between the fulcrums 23 and 24 (hereinafter, referred to as the length of the legs) can be changed to an arbitrary length by lengthening or shortening the distance between the fulcrums 23 and 24 by a driving device 26 attached to the legs 25.

In order to control the position and posture of the movable member 22, first, the coordinates of each fulcrum 24 of the movable member 22 corresponding to the desired position and posture of the movable member 22 are obtained. Fixing member 21
Since the coordinates of each fulcrum 23 are fixed, the length of each leg can be obtained from the coordinates of each fulcrum 24 of the movable member 22. Therefore, by controlling each driving device 26 so that the leg length obtained here is obtained, the movable member 22 is moved to a desired position and posture, and the position and posture of the movable member 22 are controlled to a desired state. it can.

FIG. 3 is a block diagram showing the configuration of a conventional numerical controller for a parallel mechanism machine tool that performs the above-described control. The program interpreter 1 interprets a given machining program block by block to generate block information BI. The function generation unit 2 receives the block information BI and inputs interpolation coordinates (X, Y, Z, and X) indicating the position and orientation of the movable member 22 at each time in each function generation cycle.
A, B, C) are obtained by interpolation and output.

Next, in the inverse mechanism conversion unit 14, the interpolation coordinates (X, Y, Z, A, B, C) for each function generation cycle are calculated.
Length of each leg (L1 ', L1
2 ′, L3 ′, L4 ′, L5 ′, L6 ′).

In the following acceleration / deceleration processing section 13, each leg before acceleration / deceleration processing is controlled so that the speed of change of the length of each leg smoothly changes during acceleration / deceleration in order to operate the drive device smoothly during acceleration / deceleration. Length (L1 ′, L2 ′, L3 ′, L
4 ′, L5 ′, L6 ′) by the acceleration / deceleration processing, and the lengths (L1 ″, L2 ″, L3 ″, L) of the respective legs after the acceleration / deceleration processing.
4 ", L5", L6 ").

FIGS. 4 (a) and 4 (b) show, respectively, the temporal transition relation between the change speed of each leg length before the acceleration / deceleration process and the change speed of each leg length after the acceleration / deceleration process. An example is shown. The drive device control unit 15 determines the length (L1 ″, L1) of each leg after the acceleration / deceleration processing output from the acceleration / deceleration processing unit 13.
2 ", L3", L4 ", L5", L6 "), the drive of the driving device is controlled so that the length of each leg is set to a predetermined value.

[0009]

The length of each leg before the acceleration / deceleration processing in the above-mentioned prior art is calculated by interpolating coordinates obtained by interpolating a command value given in a Cartesian coordinate system for each function generation cycle. Since it is converted into the length of each leg, the cutting edge position calculated back from the length of each leg before the acceleration / deceleration processing is on the command value given in the Cartesian coordinate system. However, since the conversion from the interpolation coordinates obtained by interpolating the command value for each function generation cycle to the length of each leg before the acceleration / deceleration processing is a non-linear conversion, the conversion from the length of each leg before the acceleration / deceleration processing is performed. Even if the conversion to the length of each leg after acceleration / deceleration processing is a linear conversion, the cutting edge position calculated backward from the length of each leg after acceleration / deceleration processing deviates from the command value given in the Cartesian coordinate system. Causes a trajectory error.

FIG. 5 shows a command value given in a Cartesian coordinate system, a cutting edge position calculated backward from the length of each leg before acceleration / deceleration processing, and a back calculation from the length of each leg after acceleration / deceleration processing. An example of the relationship with the position of the cutting edge is shown. The line segment AB is a straight line command given in the Cartesian coordinate system. Points P1 to P11 are cutting edge positions that are back calculated from the lengths of the respective legs before the acceleration / deceleration processing.
The points Q1 to Q11 are the cutting edge positions calculated backward from the lengths of the respective legs after the acceleration / deceleration processing, and there is a problem that a considerably large trajectory error occurs between the two.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cutting edge position calculated from a command value given in a Cartesian coordinate system and the length of each leg after acceleration / deceleration processing. It is another object of the present invention to provide a numerical controller for a parallel mechanism machine tool in which the above-mentioned trajectory error is prevented from occurring during the operation.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a program interpreting means for interpreting a machining program, and to output interpolation coordinates for each Cartesian coordinate of a movable member based on an output of the program interpreting means for each function generation cycle. Function generating means, acceleration / deceleration processing means for converting interpolation coordinates for each function generation cycle so that the speed of each component of the Cartesian coordinates changes smoothly, Cartesian coordinates after acceleration / deceleration processing by the acceleration / deceleration processing means This is effectively achieved by providing reverse mechanism converting means for converting the length of each leg into the length of each leg and outputting the result, and driving device control means for controlling the driving of the driving device based on the output of the reverse mechanism converting means.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a numerical control device for a parallel mechanism machine tool according to the present invention. The program interpreting unit 1 and the function generating unit 2
This is the same as that used in the conventional numerical controller for a parallel mechanism machine tool shown in FIG.

Movable member 22 output from function generator 2
Interpolation coordinates (X, Y, Z, A, B,
C) is converted by the acceleration / deceleration processing unit 3 so that the speed of each component of the Cartesian coordinates changes smoothly, and the Cartesian coordinates (X ′, Y ′, Z ′, A ′, B ′,
C ′).

The inverse mechanism conversion unit 4 converts the Cartesian coordinates (X ', Y', Z ', A', B ', C') after the acceleration / deceleration processing into the lengths (L1) of the respective legs after the acceleration / deceleration processing. , L2, L3, L4, L
5, L6). Then, the driving device control unit 5
The length of each leg after this acceleration / deceleration processing (L1, L2, L3, L
4, L5, L6).

[0016]

As described above, according to the numerical controller for a parallel mechanism machine tool of the present invention, the Cartesian coordinates representing the position and posture of the movable member are converted into the length of each leg after the acceleration / deceleration processing. Therefore, the cutting edge position calculated backward from the length of each leg after the acceleration / deceleration processing is always on the command value given in the Cartesian coordinate system. Therefore, eliminating the trajectory error,
Processing accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a numerical control device according to the present invention.

FIG. 2 is a perspective view showing an example of a main part of a machine tool to which a parallel mechanism is applied.

FIG. 3 is a block diagram illustrating a configuration of a conventional numerical control device.

FIG. 4 is a diagram showing an example of a relationship between time and a change speed of the length of each leg in a conventional numerical control device;
(A) is the change speed of the length of each leg before the acceleration / deceleration processing, (b)
Shows the relationship with the change speed of the length of each leg after the acceleration / deceleration processing.

FIG. 5 shows a conventional numerical control device, a command value given in a Cartesian coordinate system, a cutting edge position calculated back from each leg length before acceleration / deceleration processing, and a length of each leg after acceleration / deceleration processing. It is a figure which shows an example of the relationship with the cutting edge position calculated backward from FIG.

[Explanation of symbols]

1. Program interpreting section, 2 function generating section, 3 acceleration / deceleration processing section, 4 reverse mechanism converting section, 5 drive control section, 21
Fixed member, 22 movable member, 23 fulcrum of fixed member, 2
4 fulcrum of movable member, 25 legs, 26 driving device.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasushi Fukaya 5-25-25 Shimokoguchi, Oguchi-machi, Niwa-gun, Aichi Prefecture F-term in Okuma Plant Oguchi Plant (reference) 5H269 AB01 AB33 BB03 CC10 RB11 RC04

Claims (1)

[Claims] 1. A program interpreting means for interpreting a machining program, a function generating means for outputting interpolation coordinates for each function generating cycle for Cartesian coordinates of a movable member based on an output of the program interpreting means, and each component of the Cartesian coordinates Acceleration / deceleration processing means for converting the interpolation coordinates for each of the function generation cycles so that the speed changes smoothly, and the Cartesian coordinates after the acceleration / deceleration processing by the acceleration / deceleration processing means are converted into the length of each leg and output. A numerical controller for a parallel mechanism machine tool, comprising: a reverse mechanism converting means for performing a driving operation; and a drive control means for controlling the driving of the driving device based on an output of the reverse mechanism converting means.