Boots – shoes – and leggings
Patent
1997-06-27
1998-10-20
Gordon, Paul P.
Boots, shoes, and leggings
36447431, 364179, G05B 194103
Patent
active
058256547
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for a velocity control of electric drives.
BACKGROUND INFORMATION
In modern industrial controls for use, for example, in machine tools and robots, the problem frequently arises that the path velocity profile prescribed on the desired-value side in the form of the feed overshoots the possible axial velocity and axial acceleration and, as a result, there is an increase in the axial drag error, a velocity error in the longitudinal direction of the workpiece. Generally, the result of this on curved contours is also a contouring error on the workpiece to be produced. In addition, in the vicinity of singular regions, i.e., discontinuous points on the contours such as break points, the axial monitoring of the drag error of the machine is triggered and causes an immediate stoppage of the machine. Since, in view of the finest contours which are at present to be produced, the aim within the framework of narrow tolerances is to minimize by means of an axial drag error these copying errors which occur, there is the need to reduce the fundamental axial velocity and axial acceleration so that axial drag errors can be avoided.
It is known that conventional methods of velocity control for the purpose of fulfilling these requirements in machine tool controls, to the extent that they smooth the path velocity profile, either only take account of a flat-rate velocity-independent path acceleration limit and path velocity limit, or else derive these latter from the course of the machine axes or basic axes under greatly simplified conditions. These methods employed as standard for velocity control in machine tool controls have the disadvantage, however, that, on one hand, a permissible flat-rate acceleration limit has to be selected to be appropriately small in order to avoid axial drag errors and contouring errors caused thereby. As a result, however, the performance of the machine is not exploited. On the other hand, the conventional method, discussed above, for deriving a path acceleration limit and a path velocity limit has the result that the latter are calculated too coarsely for detection of abruptly occurring singular regions. The required dynamic path limits which could prevent triggering of the axial drag error monitoring are thus not determined with sufficient accuracy in the vicinity of singular regions. For this reason, the machine operator of small subprograms generally adapts the programmed feed to the acceleration possibilities of his machine manually by means of programmable acceleration limits. Such a mode of procedure has the disadvantage, however, that the manual adjustment of the velocity profile in the contouring is very uneconomic, since very extensive programs are run only a few times. An alternative to such a procedure includes approximating the courses of the machine axes. This is generally done via linear records (in this connection, see German Patent Application No. 36 23 070 or European Patent Application No. 0 254 884, for example). However, the latter mode of procedure has the disadvantage that the program outlay is thereby increased, it is no longer possible to change a tool correction subsequently and a clamping correction is then possible only to a very limited extent.
Japanese Patent Application No. 507 3128 describes a method for controlling feed rates which avoids an abrupt lowering of the feed rate. However, this Japanese Patent Application does not describe measures for optimum utilization of the performance of a machine being used in conjunction with a consideration of velocity limits and acceleration limits.
It is therefore the object of the invention to design a method for velocity control in such a way that the disadvantages represented above such as limiting the performance of the machine employed, a higher outlay due to manual adaptation and excessive programming outlay through approximating the courses of the machine axes can be avoided. Rather, local path acceleration limits and path velocity limits are to be deriv
REFERENCES:
patent: 5444636 (1995-08-01), Yoshida et al.
patent: 5528506 (1996-06-01), Yoshida et al.
Speth Wolfgang
Westermeyer Wilhelm
Garland Steven R.
Gordon Paul P.
Siemens Aktiengesellschaft
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