Development of 2-DOF tilting actuator with remote center of rotation for human operated non-contact handling tool

Abstract

This paper describes the development of a new and unique 2-DOF tilting actuator that has a remote center of rotation. The tilting actuator is part of a non-contact handling tool that allows thin contact sensitive objects like silicon wafers or coated sheet metal to be manipulated without any contact between the tool and the object. Tilting is necessary to keep the object aligned with the levitator during large planar accelerations, similar to how a waiter tilts a tray of beverages during transport. A feed-forward tilt implementation based on known acceleration eliminates the need of sensor, but it requires that the center of rotation coincides with the center of mass of the levitated object to avoid disturbances by the tilting action. This is realized by a mechanical solution of a dome-shaped structure that is supported by three ball bearings on the inner surface. The tilting actuator is attached to an in-house developed admittance controlled SCARA-type haptic device, which allows both automated and human operated manipulation. In this collaborative system, where the haptic device assists the human operator in real time, the human operator can successfully perform the manipulation task with ease and without failure, which would not have been possible without the haptic assistance.