Data processing: generic control systems or specific application – Specific application – apparatus or process – Robot control
Reexamination Certificate
2000-02-18
2001-09-04
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Robot control
C700S245000, C700S247000, C700S253000, C700S257000, C700S251000, C700S259000, C700S256000, C700S252000, C700S260000, C700S250000, C700S189000, C318S568130, C318S568140, C318S568150, C318S568160, C219S125110, C219S125120, C701S002000, C701S023000
Reexamination Certificate
active
06285920
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of teaching robot movements.
2. Description of the Prior Art
Programmable robots are commonly used for a variety of repetitive industrial applications. As appreciated, a robot only performs tasks and motions that are preprogrammed. Programming of robot motions can be a complicated and time-consuming process. Methods of reducing programming time include programming robot motions by lead through teaching. Typical lead through teaching methods include the steps of moving the robot through a set of desired motions, sensing specific points during the movement of the robot, recording the specific points in a microprocessor, and utilizing the recorded points to create movement commands. The robot repeats the desired motions according to the created movement commands. An operator programming a robot utilizing a lead through teach method is responsible for guiding the robot and for maintaining the desired position and orientation of the robot in three or more dimensions. A drawback to conventional lead through teach methods is that an operator must constantly guide the robot through motions burdened with the requirement to accurately guide the robot through the desired motion while never allowing a collision with an object in the workspace and never allowing the robot to apply excessive pressure to the workpiece. As shown in
FIG. 1
, the operator polishing a small mold
26
can easily manipulate a hand held polishing tool
28
. Referring to
FIG. 2
, when the same polishing tool
28
is attached to an end of the robot
12
, the task becomes burdensome to the operator and intuitive movements by the operator made with the polishing tool
28
become difficult, resulting in less then desirable programmed movements of the robot
12
. Additionally, the mold
26
can be damaged if the polishing tool
28
errantly crashes with the mold
26
or applies excessive pressure to the mold
26
due to the operator's inability to overcome the inertial forces of the robot
12
or to otherwise guide the robot
12
along the desired path.
Improvements on this method include the use of various types of teaching handles (not shown) that aid the operator in guiding the robot through the desired motions. Teaching handles improve the operator's mechanical advantage over the robot, however the operator is still left to manipulate and accurately control the robot through the desired motions while maintaining control in three or more dimensions.
Further, some applications require that an end of arm tool be controlled within a tight tolerance relative to the workpiece. Robots are known to utilize a touch sensor that contacts the workpiece during operation. U.S. Pat. No. 5,906,761 to Gilliland et al. utilizes a touch sensor incorporated into a tip of a welding torch. The touch sensor allows the robot to maintain a predetermined distance between the welding tip and the workpiece during welding operations. However, the predetermined distance is maintained during the welding operations not during the teaching of the robot, thereby still leaving the burdensome task to the operator of accurately guiding the robot during teaching.
Consequently, there is a need for a method that allows the operator to teach robot motions while concurrently maintaining a spatial relationship between the robot and the workpiece. Further, it is desirable to free the operator from having to guide the robot in three dimensions during teaching operations in an effort to reduce the complexity of programming desired motions of the robot. Further, simplification of the teaching operation allows for more efficient teaching of robot motions, making additional uses of programmable robots economically feasible.
SUMMARY OF THE INVENTION AND ADVANTAGES
A method of teaching a robot having a robot fixture for cooperating with a workpiece, at least one sensor, and a microprocessor for controlling motion of the robot fixture relative to the workpiece is disclosed. The method comprises the steps of storing a predetermined selected spatial relationship between the robot fixture and the workpiece in the microprocessor, imparting movement onto the robot, recording the imparted movement on the robot in the microprocessor, using the recorded imparted movement to establish initial movement commands, continuously sensing a spatial relationship of the robot fixture relative to the workpiece during movement of the robot, and comparing the sensed spatial relationship of the robot fixture relative to the workpiece to the predetermined selected spatial relationship to determine a deviation from the predetermined selected spatial relationship between the robot fixture and the workpiece. The method is characterized by modifying the imparted movement on the robot based upon the determined deviation from the predetermined selected spatial relationship between the robot fixture and the workpiece to maintain the predetermined selected spatial relationship of the robot fixture relative to the workpiece as the robot moves relative to the workpiece during teaching of the robot.
This method allows an operator to teach robot motions while concurrently maintaining a relationship between the robot fixture and the workpiece. Further, this method frees the operator from guiding the robot in at least one dimension during teaching operations, reducing the complexity of programming desired motions of the robot. Additionally, this method simplifies the teaching operation, allowing quicker teaching of robot motions, making heretofore economically unfeasible uses of programmable robots feasible.
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Lee Eric C.
McGee H. Dean
Swanson Peter
Cuchlinski Jr. William A.
Fanuc Robotics North America
Howard & Howard
Marc McDieunal
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