Vision Based Automatic Theodolite for robot calibration /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | This research has involved design, development, and application of an automatic partial pose measurement system for robot calibration. The Vision Based Automatic Theodolite (VBAT) uses low resolution rotation stages and resolution enhancement from a vision system to determine the line-of-sight to a spherical illuminated target. Automatic tracking, focusing, and centering provide the calibration system with speed, reliability, and repeatability. It is shown that the vision system resolution enhancement may be modeled as an additional two degree-of-freedom kinematic mechanism, resulting in exactly 4 independent vision parameters in addition to the rotation stage kinematic parameters. It is proposed that such a measurement prototype m ay be constructed without expensive precision machining, provided it is calibrated before use. Simulations are used to demonstrate that such a system m ay be identified using a hybrid approach: precalibration of the vision parameters, followed by calibration of the rotation stage parameters. All parameters are determined from measurements using a Coordinate Measuring Machine. The parameter identification is formulated as a non-linear regression problem, precluding the need for an explicit Jacobian relating the model parameters to the line-of-sight parameters. Verification of the VBAT calibration experiment showed that the identified model could predict the target position to a root mean square miss-distance of 0.2 mm. The VBAT was used to calibrate a PUMA 560 robot. This robot has been measured to be inaccurate by as much as 14 mm. The calibrated robot model predicts the position of the robot target to a root mean square error of 0.4 mm. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Mechanical engineering." |
| Physical Description: | xi, 138 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |