Tool center point calibration apparatus and method
AssigneeCycle Time Corporation
InventorHenry F. Thorne
Life of this patent
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Abstract
The present invention provides a tool center point calibration apparatus and method for accurately determining appropriate tool center points for a robot to allow for proper tool alignment and correction of robot programs. The calibration apparatus includes a calibration beam on a single line.
Claims15
A method for tool calibration for a robot with a robot face plate having a tool with a tip axis, said method comprising the steps of:
- a) positioning a calibration means within the robot envelope, wherein said calibration means includes a beam having a centerline positioned along a single line;
- b) positioning said tool tip to an initial position within the path of said beam;
- c) obtaining values of said robot face plate with said tool tip positioned within said beam path;
- d) rotating said tool about said tip axis to at least a second position with said tool tip positioned within said beam path;
- e) obtaining values of said robot face plate with said tool tip positioned at said at least second position;
- and
- f) calculating a tool center point based upon said obtained values.
A method for tool calibration for a spot welding robot having a robot face plate with a welding tool attached to said robot face plate and including a pair of opposed tool tips positioned along a tool axis, said method comprising the steps of:
- a) positioning a calibration means within the robot envelope, wherein said calibration means includes a beam having a centerline positioned along a single line;
- b) positioning a first of said pair of opposed tool tips within the path of said beam;
- c) profiling said first tool tip by moving said welding tool relative to said beam;
- d) positioning said first tool tip to an initial position based upon said profiling where said beam path intersects said first tool tip at a center point positioned at a midpoint of a substantially cylindrical portion of said first tool tip;
- e) calculating an initial approximation for said center point position of said first tool tip;
- f) obtaining values of said robot face plate with said tool tip at said initial position;
- g) rotating said welding tool from said initial position to a second position about an axis substantially perpendicular to said calibration means to a second position;
- h) obtaining values of said robot face plate with said tool tip at said second position;
- i) rotating said welding tool about said axis substantially perpendicular to said calibration means to a third position;
- j) obtaining values of said robot face plate with said tool tip at said third position;
- k) rotating said welding tool about an axis substantially parallel to said calibration means to a fourth position;
- l) obtaining values of said robot face plate with said tool tip at said fourth position;
- m) calculating said center point position of said first tip based upon said obtained values;
- n) repeating steps b through m for the second of said pair of tool tips;
- and
- o) calculating said tool centerline which is along the line extending between the center points of said pair of tool tips.
The method of tool calibration for a robot comprising the steps of:
- a) positioning a calibration means with the robot envelope, wherein said calibration means includes a beam having a centerline positioned along a single line;
- b) positioning said tool within the path of said beam;
- c) profiling said tool by moving said tool relative to said beam to sequentially determine cross-sectional lengths of said tool in planes parallel to said calibration means, wherein a plurality of substantially similar cross-sectional lengths indicates a substantially cylindrical portion of said tool;
- d) calculating a midpoint of said tool along said substantially cylindrical portion;
- and
- e) aligning said tool based upon said calculated midpoint.
Dependencies are inferred from the claim text.