Unitary specimen prealigner and continuously rotatable four link robot

Abstract

A unitary prealigner and four link robot arm includes an upper arm, a middle arm, a forearm, and a hand that is equipped with vacuum pressure outlets to securely hold a specimen. The robot arm is carried atop a tube that is controllably positionable along a Z-axis direction. The prealigner is attached to the tube by a movable carriage that is elevatable relative to the robot arm. The prealigner further includes a rotatable chuck having a vacuum pressure outlet for securely holding a specimen in place within an edge detector assembly that senses a peripheral edge of the specimen. The prealigner may be elevated to receive a specimen from the robot arm or it may be lowered to allow clearance for the robot arm to rotate. In operation, the robot arm retrieves a specimen and places it on the prealigner, which performs an edge scanning operation to determine the effective center and specific orientation of the specimen. The robot arm then performs angular and extension correction operations to position the grasp center of the hand over the effective center of the specimen, thereby placing the specimen in a predetermined alignment relative to the hand. Finally, an exchange of vacuum pressure releases the specimen from the prealigner and secures it once again on the hand, and the robot arm delivers the specimen in the predetermined alignment to a processing station at a second elevation and at a location that compensates for the angular and extension correction operations.