Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1986-10-16
1987-10-13
Shoop, Jr., William M.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
2191251, 901 3, 901 4, 901 14, 901 42, 318568, G05B 1918
Patent
active
047001186
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a a robot workpiece Cartesian coordinate system setting system capable of setting a tool nose position (TCP) of a working member mounted on the wrist of an articulated robot.
2. Background Art
Industrial robots having various operating configurations have been developed, among which are polar coordinate system-type robots and articulated robots. Among these, the most widespread are articulated robots employed widely in arc welding and generally having five or six degrees of freedom, wherein link mechanisms are arranged to form an arm drive system. For example, an articulated robot configuration having six degrees of freedom includes an axis for arm sweep (.theta. axis), an axis for back-and-forth swiveling of a lower arm (W axis), an axis for up-and-down swiveling of an upper arm (U axis), and axes for rotating, bending and twisting a wrist (hand) (.alpha., .beta. and .gamma. axes, respectively). These axes are controlled independently of one another and the tool mounted on the hand is moved in accordance with the command data to cause the robot to perform a series of welding operations.
The blocks which are the basic elements of the robot command data are composed of G codes, F codes, position data and S codes. In order to improve the precision of tool control, it is necessary to correctly input the position data above all. To facilitate the creation of the command data, the arrangement is such that a plurality of workpiece Cartesian coordinate systems having a fixed relationship to the reference coordinate system of the robot can be set when the robot repeats the same operation at a plurality of working positions. However, in the conventional setting system in which metric values along each motion axis are inputted as set values and three fundamental axes XYZ are defined by hand vectors using the TCP of the hand as a reference point when the robot is at this position, a workpiece Cartesian coordinate system having a prescribed angle of rotation between itself and the reference coordinate system of the robot cannot be defined if the hand cannot be pointed in a predetermined direction in e.g. a five-axis robot. In addition, an operation for bringing the hand vectors into coincidence in the space of the Cartesian coordinate system that is desired to be designated is not easy.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a robot workpiece Cartesian coordinate system setting system which makes it possible to set a tool position through a simple method and to control a robot in a highly precise manner.
In accordance with the present invention, there is provided a system for setting a workpiece Cartesian coordinate system of a robot when an articulated robot having a plurality of motion axes is taught and operated, characterized by having a working member mounted on a wrist of a hand of the robot, teaching means for manually feeding the hand and teaching position data, memory means for storing position data indicative of a taught tool nose position (TCP), arithmetic means for deciding a unit vector along each axis in a reference coordinate system of the robot based on position data storing a taught reference point, any point on a predetermined axis and a third poing defining a plane together with the other two points, and control means for driving the robot upon setting a workpiece coordinate system as set data based on unit vectors of a decided tool coordinate system.
More specifically, according to the present invention, the user moves the tool mounted on the hand to teach the reference point, any point on the predetermined axis and the third point defining the plane together with the other two points, whereupon a single coordinate system is specified by the position data indicative of these three points P1, P2, P3. Therefore, according to the invention, a tool position can be set through a simple method and the robot can be controlled in a highly precise manner.
Further, according to the present invention, a coordina
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Karakama Tatsuo
Kishi Hajimu
Sakakibara Shinsuke
Fanuc Ltd.
Martin David S.
Shoop Jr. William M.
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