Vision seam tracking method and apparatus for a manipulator
First Claim
1. A method of controlling a manipulator to effect motion of a tool centerpoint associated with a function element carried by the manipulator such that the tool centerpoint moves along a path detected by a sensor during execution of a program defining a cycle of operation of the manipulator, the method comprising the steps of:
- a. periodically producing intermediate point signals representing coordinates of an intermediate location along a predetermined path between two programmed locations, the intermediate location defining displacement along the predetermined path to be effected in a predetermined time interval;
b. producing target coordinate signals in response to the intermediate point signals and the sensor, the target coordinate signals representing coordinates of a location to which the tool centerpoint is to be moved in the direction from the tool centerpoint current location toward the detected path;
c. calculating a limit value defining, for the predetermined time interval, a maximum deviation of the path of actual tool centerpoint motion from the predetermined path;
d. calculating coordinates of a predicted location of the tool centerpoint, the predicted location being defined by the intermediate point and an offset between the current tool centerpoint location and the immediately preceding intermediate point;
e. calculating the magnitude of the distance between the target point and the predicted location;
f. determining whether the magnitude of the distance exceeds the limit value; and
g. modifying the target coordinate signals in response to determining that the magnitude of the distance exceeds the limit value, the modified target coordinate signals defining a location to produce a deviation equal to the limit.
2 Assignments
0 Petitions
Accused Products
Abstract
A three-dimensional vision seam tracking method and apparatus for controlling the motion of the center point of a tool mounted on a manipulator. The manipulator is provided with a control to operate the manipulator members to move the tool center point at programmed velocities along a programmed path corresponding to the seam. The manipulator is provided with a vision system including a laser scanner/camera head mounted ahead of the function element. The control is programmed with dynamically varying orientation angles to control the orientation of the tool during seam tracking. The laser scanner/camera head scans the seam at predetermined time intervals. A set of coordinates for the center point of the seam in a coordinate system relative to the camera is provided for each scan. The sets of camera coordinates are transformed to the coordinate system of the manipulator using transformation matrices employing the orientation angles in effect at the time of the scan for the set of camera coordinates being transformed. The transformed coordinates are stored in a FIFO buffer until needed. The seam tracking routine of the manipulator control removes FIFO entries at some later time and alters the manipulator'"'"'s programmed path to move the tool center point along the seam.
99 Citations
14 Claims
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1. A method of controlling a manipulator to effect motion of a tool centerpoint associated with a function element carried by the manipulator such that the tool centerpoint moves along a path detected by a sensor during execution of a program defining a cycle of operation of the manipulator, the method comprising the steps of:
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a. periodically producing intermediate point signals representing coordinates of an intermediate location along a predetermined path between two programmed locations, the intermediate location defining displacement along the predetermined path to be effected in a predetermined time interval; b. producing target coordinate signals in response to the intermediate point signals and the sensor, the target coordinate signals representing coordinates of a location to which the tool centerpoint is to be moved in the direction from the tool centerpoint current location toward the detected path; c. calculating a limit value defining, for the predetermined time interval, a maximum deviation of the path of actual tool centerpoint motion from the predetermined path; d. calculating coordinates of a predicted location of the tool centerpoint, the predicted location being defined by the intermediate point and an offset between the current tool centerpoint location and the immediately preceding intermediate point; e. calculating the magnitude of the distance between the target point and the predicted location; f. determining whether the magnitude of the distance exceeds the limit value; and g. modifying the target coordinate signals in response to determining that the magnitude of the distance exceeds the limit value, the modified target coordinate signals defining a location to produce a deviation equal to the limit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for controlling a manipulator to effect motion of a tool centerpoint associated with a function element carried by the manipulator such that the tool centerpoint moves along a path detected by a sensor during execution of a program defining a cycle of operation of the manipulator, the apparatus comprising;
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a. means for periodically producing intermediate point signals representing coordinates of an intermediate location along a predetermined path between two programmed locations, the intermediate location defining displacement along the predetermined path to be effected in a predetermined time interval; b. means for producing target coordinate signals in response to the intermediate point signals and the sensor, the target coordinate signals representing coordinates of a location to which the tool centerpoint is to be moved in the direction from the tool centerpoint current location toward the detected path; c. means for calculating a limit vale defining, for the predetermined time interval, a maximum deviation of the path of actual tool centerpoint motion from the predetermined path; d. means for calculating coordinates of a predicted location of the tool centerpoint, the predicted location being defined by the intermediate point and an offset between the current tool centerpoint location and the immediately preceding intermediate point; e. means for calculating the magnitude of the distance between the target point and the predicted location; f. means for determining whether the magnitude of the distance exceeds the limit value; and g. means responsive to the determining means for modifying the target coordinate signals to define a location resulting in a deviation equal to the limit. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification