Method for determining auxiliary position-control parameters

Details Method for determining auxiliary position-control parameters Method for determining auxiliary position-control parameters

1993-06-14

1996-04-23

Envall, Jr., Roy N.

Cutlery

36447431, 36447412, 318567, 31856822, G05B 1900

Patent

active

055109969

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is based on a method for increasing the precision of paths in numerically controlled machine tools, and more particularly to a method of determining a parameter for auxiliary control in a position control loop of the numerically controlled path of a machine having i axes. One proposal for increasing path precision by superimposing auxiliary values is known from "Zeitschrift fur industrielle Fertigung" (Journal for Industrial Manufacturing), 1978, Pages 329 to 333. This reference describes a plurality of possibilities for influencing the guidance variable of the position control of a machine tool. In this prior art method of auxiliary control, the desired position signal is supplemented by adding suitably weighted control signals. The particular goal of the arrangements proposed in the Journal for Industrial Manufacturing, 1978, Pages 329-333 is to improve path precision while travelling through a corner. With respect to the superimposition of auxiliary values, the reference is limited to the possibility of auxiliary control of speed, i.e., superimposing an auxiliary signal that is proportional to the guidance speed. Auxiliary control of the accelerated guide speed, i.e., superimposing an auxiliary value in the form of an acceleration signal proportional to guidance acceleration or greater derivations of the guidance variable, is not provided. This reference does not give any information on how the auxiliary control parameters required for carrying out the auxiliary control for greater derivations of guidance variables can be obtained.
EP 0,184,036 also discloses a control method for NC machines that employs the auxiliary control method. Moreover, NC (numerically controlled) control units are available commercially, for example, from the FANUC and OSAI companies of Japan, which also use the auxiliary speed control method. The parameters required for auxiliary control in this case are exactly predetermined or they are set empirically for each machine.


SUMMARY OF THE INVENTION

It is the object of the present invention to provide a method which permits the systematic determination of auxiliary control parameters for any desired machine.
This objective is attained by a method in which: a position value changing over time in the form of a ramp is given as a guidance variable for the position control of the i-th axis; the steady-state error of the i-th axis between the guidance variable and the actual position value is detected; a speed auxiliary control parameter is derived from the steady-state error; and the speed auxiliary control parameter is transferred to a control unit. The method is not machine specific and may be used for any desired machine. It can be carried out without performing an expensive identification of the control path. In addition to determining a parameter for the auxiliary control of the speed in a simple manner, it permits further parameters for auxiliary control of acceleration and for auxiliary control of jolts to be obtained, and it may also be used on any desired position control path. It can advantageously be performed automatically and it is particularly suitable for implementation in a microcomputer. The structure of the evaluation algorithm is simple, which makes it possible to incorporate it into very cost-effective control units. Another advantage is that for the auxiliary control of greater derivations of the position guidance variable by way of the auxiliary control parameters obtained according to the invention for a great number of different position control paths, the lag error becomes nearly zero, even in the dynamic movement state. Another advantage of the method is that it can be executed very rapidly. The method according to the invention is described in more detail in the specification below and by way of the drawing.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an arrangement for carrying out the method according to the invention on one axis;
FIGS. 2a and 2b show position guidance variables employed

REFERENCES:
patent: 4695960 (1987-09-01), Reimann et al.
patent: 4825055 (1989-04-01), Pollock
patent: 4906908 (1990-03-01), Papiernik et al.
patent: 5037252 (1991-08-01), Hasegawa et al.
"Zeitschrift fur industrielle Fertigung" (Journal for industrial Manufacturing), 1978, pp. 329-333.
Von Klaus Mezger et al, "Kleinste Schlepp-und Bahnfehler in NC-Systemen", Technische Rundschau, vol. 81, No. 36, Sep. 8th, 1989, pp. 164-167.

Affiliated with

Also associated with

Rating

Method for determining auxiliary position-control parameters does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for determining auxiliary position-control parameters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for determining auxiliary position-control parameters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2314337