Off-line programmable robot

• US 4,590,578 A
• Filed: 07/11/1983
• Issued: 05/20/1986
• Est. Priority Date: 07/11/1983
• Status: Expired due to Fees

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Walsh, Peter M., Gardner, Stephen M., Dondero, Richard F., Fitzpatrick, Peter R., Demers, Kenneth P., Barto, John J. Jr.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Lastova, John R.
• Application Number:
  US06/512,829
• Time in Patent Office: 1,044 Days
• Field of Search: 364/513, 364/167, 364/191, 364/192, 364/193, 364/571, 318/568, 318/632, 901/2, 901/3, 901/5, 901/6, 901/8-10, 901/14, 901/16, 901/30, 901/33, 901/35, 901/46, 901/47
• US Class Current: 700/254
• CPC Class Codes: B21J 15/10 Riveting machines electric heating elements H05B
• CPC Class Codes: B25J 11/0055 Cutting
• CPC Class Codes: B25J 11/007 Riveting
• CPC Class Codes: B25J 15/0052 multiple gripper units or multiple end effectors
• CPC Class Codes: B25J 15/0057 mounted on a turret
• CPC Class Codes: B25J 15/0066 with different types of end effectors, e.g. gripper and welding gun B25J15/0057 and B25J15/0061 take precedence
• CPC Class Codes: B25J 19/021 Optical sensing devices
• CPC Class Codes: B25J 5/02 travelling along a guideway
• CPC Class Codes: B25J 9/046 Revolute coordinate type
• CPC Class Codes: G05B 19/4083 Adapting programme, configuration
• CPC Class Codes: G05B 2219/33078 Error table, interpolate between two stored values to correct error
• CPC Class Codes: G05B 2219/36503 Adapt program to real coordinates, software orientation
• CPC Class Codes: G05B 2219/39024 Calibration of manipulator
• CPC Class Codes: G05B 2219/40272 Manipulator on slide, track
• CPC Class Codes: G05B 2219/41091 Alignment, zeroing, nulling, set parallel to axis
• CPC Class Codes: G05B 2219/45083 Manipulators, robot
• CPC Class Codes: G05B 2219/49195 Slide, guideway, robot arm deviation
• CPC Class Codes: G05B 2219/50033 Align tool, tip with a calibration mask

Abstract

Machine operations are performed by a robot at a plurality of locations on a workpiece based on off-line data. The off-line data is corrected based on two levels of workpiece/robot alignment. First the robot determines the orientation of a fixture to which the workpiece is mounted by "touching-off" on known reference points (touchblocks) on the fixture. Coordinate data for the location of local features on the workpiece is corrected based on the first level of alignment and the positions of the local features are then sensed to provide a coordinate transformation for subsequent application to nominal machine operation location coordinates. The local features may be preassembly rivets and provide for individualized robot response on a workpiece-by-workpiece basis.

Claims

1. A method for accurately performing a machine operation at a plurality of locations on a workpiece with a robot that is under the direction of a controller, that comprises:

mounting the workpiece in a predetermined manner to a fixture;

providing a plurality of alignment points on the fixture;

positioning the robot to measure the position of the alignment points and providing coordinate data to the controller indicative of the measured position of the alignment points;

determining a first coordinate transformation based on the measured alignment point coordinates and storing said first coordinate transformation in the controller;

providing at least two local features on the workpiece;

providing nominal local feature coordinates to the controller indicative of the expected location in robot coordinates of the at least two local features on the workpiece;

applying the first coordinate transformation to the nominal local feature coordinates to provide corrected local feature coordinates and storing the corrected local feature coordinates in the controller;

positioning the robot in response to the corrected local feature coordinates to measure the actual position of the at least two local features on the workpiece and providing coordinate data to the controller indicative of the measured position of the at least two local features;

determining a second coordinate transformation based on a comparison of the nominal local feature coordinates and the measured local feature position and storing the second coordinate transformation in the controller;

providing nominal machine operation location coordinates to the controller indicative of the plurality of locations on the workpiece;

applying the second coordinate transformation to the nominal machine operation location coordinates to provide corrected machine operation location coordinates and storing the corrected machine operation location coordinates in the controller.

positioning the robot in response to the corrected machine operation location coordinates to perform the machine operation at the plurality of locations on the workpiece; and

performing the machine operation at the plurality of locations on the workpiece.

2. A method for providing individualized robot response on a workpiece-by-workpiece basis according to claim 1, comprising:

altering the positions of the at least two local features on a workpiece-by-workpiece basis, while leaving the nominal local feature coordinates unchanged.

3. A method for accurately performing a machine operation at a plurality of collinear locations on a workpiece with a robot that is under the direction of a controller, that comprises:

mounting the workpiece in a predetermined manner to a fixture;

providing a plurality of alignment points on the fixture;

disposing the fixture to locate the workpiece within the robot'"'"'s work envelope;

positioning the robot to measure the position of the alignment points and providing coordinate data to the controller indicative of the measured position of the alignment points;

determining a first coordinate transformation based on the measured alignment point coordinates and storing the first coordinate transformation in the controller;

providing at least two local features on the workpiece;

providing nominal local feature coordinates to the controller indicative of the expected location in robot coordinates of the at least two local features on the workpiece;

applying the first coordinate transformation to the nominal local feature coordinates to provide corrected local feature coordinates and storing the corrected local feature coordinates in the controller;

positioning the robot in response to the corrected local feature coordinates to measure the actual position of the at least two local features on the workpiece and providing coordinate data to the controller indicative of the measured position of the at least two local features;

determining a line equation based on the measured positions of the two local features and storing the line equation in the controller;

providing machine operation location data to the controller indicative of the number and spacing for the machine operations along the line for the plurality of collinear locations on the workpiece;

applying the machine operation location data to the line equation to provide machine operation location coordinates and storing the machine operation location coordinates in the controller;

positioning the robot in response to the machine operation location coordinates to perform the machine operation at the plurality of locations on the workpiece; and

performing the machine operation at the plurality of collinear locations on the workpiece.