Robotic manipulation of ophthalmic lenses assisted by a dedicated vision system

Abstract

A robotic system developed to manipulate ophthalmic lenses during the edging process is presented. The robot is assisted by a machine vision system to accurately determine the position and orientation of the lens optical center and axis, through the localization of two small fiducial marks on the lens surface. The optimal design of the j2ducial marks is investigated in order to minimize their size. It is shown that a regular diamond is the most detectable shape at minimum sizes. Three diferent camera placement strategies are discussed, taking into account accuracy constraints and calibration requirements; the chosen solution uses a camera attached to the robot end-effector. The robotic system proves to be advantageous with respect to the manual process, substantially improving the final accuracy while maintaining or even reducing the cycle time.

Feature-Based Object Location of IC Pins by Using Fast Run Length Encoding BLOB Analysis

“…Jiang et al [3] conducted an IC-marking inspection by using the gray relational analysis to improve the identification rate. Fernandez and Amat [4] developed a robotic system to determine the pose of the optical center of the lens and axis by using the localization of two small fiducial marks on the lens surface. Wang et al [5] presented a partial information correlation coefficient method to improve the pattern-matching method, which has been successfully applied in the IC industry.…”