Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1986-03-04
1988-09-13
Ro, Bentsu
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318568, 318632, 36416701, G05B 1918
Patent
active
047712228
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a tool coordinate system setting system and, more particularly, to a system for setting a tool coordinate system having a fixed relationship to a reference coordinate system of a robot.
The spread of robots has recently become quite conspicuous and robots are finding use in many fields. Under these circumstances, robots are required to perform both accurately and reliably.
Highly articulated robots have a large number of axes of motion and are extensively used for operations such as welding, due to their ability to execute sophisticated tasks. FIG. 5 is a perspective view of an industrial robot having five axes. In the Figure, BS denotes a base set on the floor of a factory or the like, the upper portion of the base being provided with a .theta.-axis drive mechanism 1 for driving a .theta. axis. Numeral 2 denotes a W-axis drive mechanism, 3 a W-axis arm driven by the W-axis drive mechanism 2, and 4 a U-axis arm driven by a U-axis drive mechanism 5 via a U-axis link 6. Numeral 7 denotes a robot wrist the distal end of which is provided with a hand 7a. Fixedly mounted on the hand 7a is a tool 8 such as a welding torch. Numeral 9 denotes an .alpha.-axis drive mechanism, and numeral 10 designates a .beta.-axis drive mechanism. The wrist 7, hand 7a and tool 8 are shown in enlarged form in FIG. 6.
As shown in FIG. 6, hand attitude vectors in the hand coordinate system are denoted , , , and the basic axes of the tool coordinate system are designated , , . Further, Oh represents the origin of the hand coordinate system, and TCP denotes the tool center point. Though the robot memorizes its own reference coordinate system as well as the hand coordinate system, difficulty is involved in setting the position of the tool 8 mounted on the hand 7a. Specifically, it is difficult for the robot to ascertain how the hand coordinate system and tool coordinate system are related to each other. In particular, since many kinds of tools 8 can be mounted on the hand 7a and are set at positions that differ from one another, ascertaining the correct position of a tool is a very difficult task.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a tool coordinate system setting system capable of setting a tool position through a simple method and of controlling the tool in a highly accurate manner.
The present invention provides a tool coordinate system setting system for setting a position of a tool mounted on a hand of a robot. The system is so arranged as to set and store a tool center point in the tool coordinate system, treat the tool center point as an origin, bring the axial directions of the respective basic axes of the tool coordinate system into coincidence with the axial directions of the basic axes of the robot reference coordinate system, and have the robot memorize metric values on the motion axes of the robot at the moment of coincidence as setting information for setting the tool coordinate system.
According to the present invention, the setting of tool coordinates, which was a troublesome operation in the prior art, can be performed easily and accurately through a simple method. The invention therefore has significant practical advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram for describing the setting of a tool coordinate system according to the present invention;
FIG. 2 is a perspective view for describing a jig used in setting a tool center point of a tool;
FIG. 3 is a diagram for describing the setting of a tool center point of a tool;
FIG. 4 is a flowchart indicating the setting of a tool coordinate system;
FIG. 5 is a perspective view of a common robot having multiple articulations; and
FIG. 6 is a perspective view showing, in enlarged form, a hand and a tool portion of the robot illustrated in FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will now be described in detail with reference to the drawings.
FIG. 1 is a diagram for describing the setting of a tool coordina
REFERENCES:
patent: 4456961 (1984-06-01), Price
patent: 4495588 (1985-01-01), Nio
patent: 4561050 (1985-12-01), Iguchi
patent: 4580229 (1986-04-01), Koyama
patent: 4581566 (1986-04-01), Ekstrom
Karakama Tatsuo
Nakashima Seiichiro
Sakakibara Shinsuke
Toyoda Kenichi
Fanuc Ltd
Ro Bentsu
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