Non-contact position control via fluid shear force

Non-contact position control of components is beneficial to avoid wear, damage, and nonlinearities associated with friction. Air bearings, in particular, offer non-contact, high stiffness guidance, but no means of controlling the position of the supported component. In this work, we investigate the use of shear force resulting from the air bearing fluid flow as a means of actuation. Shear force actuation is tested in an air bearing slumping system, where a flat, horizontally placed glass substrate is supported on both sides by top and bottom air bearings. We investigate the use of two methods of substrate position sensing: a fiber-optic sensor and a machine vision sensor. We show that the glass substrate position can be successfully controlled by using fluid shear force. The magnitude of the fluid shear force is measured. System identification is performed, and the results are shown to agree with a second-order model.