Method and system for controlling industrial robot

• US 4,602,345 A
• Filed: 12/20/1983
• Issued: 07/22/1986
• Est. Priority Date: 12/22/1982
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yokoyama, Shigeyoshi
• Primary Examiner(s): Ruggiero, Joseph
• Application Number:
  US06/563,517
• Time in Patent Office: 945 Days
• Field of Search: 364/513, 364/474, 364/475, 364/478, 364/191, 364/192, 364/193, 318/568, 414/730, 414/744, 901/2-5, 901/7
• US Class Current: 700/251
• CPC Class Codes: B25J 9/161 Hardware, e.g. neural networks, fuzzy logic, interfaces, processor
• CPC Class Codes: G05B 19/4083 Adapting programme, configuration
• CPC Class Codes: G05B 2219/35554 Mirror, other conversions
• CPC Class Codes: G05B 2219/36503 Adapt program to real coordinates, software orientation

Abstract

A control system and method for an industrial robot, wherein one of a plurality of command transforming programs is selected automatically depending on the number of transformed reference points (Pcn) which have been instructed, and the selected program transforms model commands into executable commands by which the robot is operated. Each transformed reference point corresponds to a model reference point (Ptn) and the model reference points are in a unique positional relation with the model commands.

Claims

1. A method of controlling a robot, comprising the steps of:

reading a model command for controlling movement of an objective of a robot, model reference points spatially correlative with positions defining operational positions of the objective and at least one transformed reference point which corresponding ones of said model reference points will have after translation of said model reference point by one of a plurality of command transformation programs for transforming said model command into an executable command;

providing an indication of the completion of said reading step;

determining the number of said transformed reference points;

selecting, in response to said indication, one of said plurality of said command transformation programs corresponding to said number of transformed reference points;

transforming said model command into an executable command using the one of said command transformation programs selected to provide for translation of said model reference point to said transformed reference point; and

operating the robot in response of said executable command.

2. The method of claim 1, further comprised of reading said model reference points after completion of the reading of said model command.

3. The method of claim 1, further comprised of reading said model reference points while simultaneously reading said model command.

4. The method of claim 1, further comprised of reading said model command after all of said model reference points have been read.

5. The method of claim 1, wherein said selected one of said plurality of programs transforms said model command into an executable command capable of effecting:

a change in the positions of said objective from said model reference points to said transformed reference point if said number of transformed reference points is one;

a change in the position of said objective from said model reference points to said transformed reference points and a change in the span of linear movement of said objective along any of three orthogonal coordinates if said number of transformed reference points is two;

a change in the position of said objective from said model reference points to said transformed reference points, a change in the span of linear movement of said objective along any of three orthogonal coordinates, and a change in the angular orientation of an axis passing through said objective relative to one of said coordinates if said number of transformed reference points is three; and

a change in the position of said objective from said model reference points to said transformed reference points, a change in the span of linear movement of said objective along any of three orthogonal coordinates, and a change in the angular orientation of said axis relative to said coordinates if said number of transformed reference points is four.

10. The method of claim 2, wherein said selected one of said plurality of programs transforms said model command into an executable command capable of effecting:

a change in the model command to cause a geometrically congruent and parallel displacement of said objective from said model reference points to said transformed reference point if said number of transformed reference points is one;

a change in the model command to cause a geometrically similar and parallel displacement of said objective from said model reference points to said transformed reference point if said number of transformed reference points is two;

a change in the model command to cause a geometrically similar and free displacement of said objective from said model reference points to said transformed reference point if said number of transformed reference points is three; and

a change in the model command to cause geometrical distortion and free displacement of said objective from said model reference points to said transformed reference point if said number of transformed reference points is four.

11. The method of claim 2, further comprising:

operating the robot to perform said model command to position the objective of the robot to a position defined by said model reference points when said number is zero.

12. The method of claim 1, wherein a command transformation program corresponding to a number greater in value than said number of transformed reference points is used during said transformation step in lieu of one of said command transformation programs corresponding to said number of transformed reference points.

13. The method of claim 1, wherein said reference points are read during said reading step by storing output signals from an encoder which shows the position of the objective of the robot when said signals indicate the occurrence of intersections of a plurality of surfaces of a model workpiece, and said transformed reference point is used by storing output signals from said encoder which indicate the occurrence of an intersection of a plurality of surfaces of a different workpiece.

6. A system for controlling a robot, comprising:

memory means for storing a plurality of command transformation programs, model commands for controlling movement of an objective of a robot, model reference points defining an initial position of the objective, and at least one transformed reference point defining a subsequent position of the objective after movement of said objective from said initial position;

means for indicating the end of storing said transformed reference points in said memory means;

detection means operatively responsive to said indicating means for counting the number of said transformed reference points stored in said memory means;

processing means including executable command generating means for reading from said memory means one of said command transforming programs selected to correspond to the number of transformed reference points counted by said detection means, and transforming said model commands into executable commands using said selected command transforming program to provide for translation of said objective from said model reference points to said transformed reference points, for providing a position command signal from said executable command; and

means for driving the robot in response to said position command.

7. The robot control system according to claim 6, wherein:

said driving means includes means for providing an encoder output indicative of changes in the position of said robot imparted by said driving means; and

said processing means includes control means for comparing said position command signal with said encoder output and for applying a differential signal to said driving means in response to the occurrence of differences between said position command signal and encoder output.

8. The robot control system according to claim 6, wherein said indicating means comprises a key operated to provide a completion signal to said processing means when storage of said transformed reference points in said memory means is completed.

9. The robot control system according to claim 6, wherein said indicating means is arranged to indicate the completion of entry of said transformed reference points into said memory means.

14. A system for controlling a robot, comprising:

a control panel having a first mode selector switch for selecting one of a teaching mode and an operational mode, and a second mode selector switch for selecting one of a model command mode and transformed command mode;

a teaching box connected with said control panel, having a plurality of axis selector switches for moving the path control objective of a robot relative to a plurality of axes, a write key and a transformed reference point setup completion key;

memory means for storing a plurality of command transformation programs, model commands for controlling movement of an objective of a robot, model reference points defining an initial position of the objective, and at least one transformed reference point defining a subsequent position of the objective after movement of said objective from said initial position;

a detector connected with said memories and operatively responsive to said transformed reference point set up completion key for counting the number of said transformed reference points stored in said fourth memory;

a central arithmetic processor connected with said control panel, said memory means and said detector, including an executable command generator and a servo-controller, said executable command generator reading from said memory means one of said command transforming programs selected to correspond to the number of transformed points counted by said detector and transforming said model commands into executable commands using said selected command transforming program to provide for translation of said objective from said model reference points to said transformed reference points and converting said executable command into a positioning command signal, said servo-controller receiving said positioning command signal to be compared with position feedback signals, said position feedback signals indicating the location of said objective;

a plurality of encoders generating said position feedback signals, and providing said position feedback signals to said servo-controller, whereby said servo-controller compares said position feedback signals of said encoders with the positioning command signal and generates differential outputs; and

a plurality of drivers connected with said central arithmetic processor and driving the robot in response to said differential outputs respectively received from said servo-controller and said executable command generator.