Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1990-03-23
1991-10-15
Shoop, Jr., William M.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318573, 318636, 31856815, G05B 1918
Patent
active
050577565
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an acceleration/deceleration control apparatus for servo control in NC machine tools, industrial robots, etc.
DESCRIPTION OF THE RELATED ART
In various machines such as NC machine tools, industrial robots, etc., which use servomotors as drive sources for individual axes, the drive of each servomotor is generally controlled for a required operation by means of a servo circuit for each axis which responds to a command applied through an interpolation circuit. In these machines, the servomotor is liable to produce vibration when the value of the command changes considerably, e.g., when the servomotor is started or stopped. Conventionally, therefore, production of the vibration is restrained by the so-called acceleration/deceleration control (see, Japanese Provisional Patent Application No. 59-168513), where a pre- or post-interpolation speed command is increased or decreased from a pre-change value to a post-change value in accordance with a predetermined function, by using one or two acceleration/deceleration filters provided ahead of the interpolation circuit or between the interpolation circuit and the servo circuit. According to the conventional acceleration/deceleration control, however, the vibration sometimes cannot be fully restrained.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an acceleration/deceleration control apparatus for servo control, capable of securely restraining vibration of servomotors mounted in various machines, such as NC machine tools, industrial robots, etc.
In order to achieve the above object, according to the present invention, an acceleration/deceleration control apparatus for servo control comprises at least one acceleration/deceleration control section, including first acceleration/deceleration control means for executing a first acceleration/deceleration process for a supplied servo control command signal, second acceleration/deceleration control means for executing a second acceleration/deceleration process for an output of the first acceleration/deceleration control means, and third acceleration/deceleration control means for executing a third acceleration/deceleration process for an output of the second acceleration/deceleration control means.
As described above, according to the acceleration/deceleration control apparatus of the present invention, the output obtained by the first acceleration/deceleration process for the supplied servo control command signal, e.g., a speed command, is subjected to the second acceleration/deceleration process. Further, the resultant output is subjected to the third acceleration/deceleration. Thus, the continuity of primary and secondary derived functions (acceleration and jerk when the speed command is supplied) of the servo control command signal with respect to the time can be secured. Consequently, when the command value of the servo control command signal changes, the command signal can be smoothly changed to a post-change commanded value, so that vibration of servomotors can be securely restrained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram showing an acceleration/deceleration control section of an acceleration/deceleration control apparatus according to a first embodiment of the present invention, the control section corresponding to one control axis of a machine used with the apparatus;
FIG. 2 is a block diagram of a first acceleration/deceleration filter shown in FIG. 1;
FIG. 3 is a diagram showing time-dependent changes of the respective outputs (speeds) of first to third acceleration/deceleration filters of the acceleration/deceleration control section of FIG. 1, along with time-dependent changes of primary and secondary derived functions (acceleration and jerk) of the outputs; and
FIG. 4 is a flow chart of control program executed by an acceleration/deceleration control apparatus according to a second embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An acceleration/decelerati
REFERENCES:
patent: 4554497 (1985-11-01), Nozawa et al.
patent: 4603286 (1986-07-01), Sakano
patent: 4706003 (1987-11-01), Nakashima et al.
Bergmann Saul M.
Fanuc Ltd.
Shoop Jr. William M.
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