M.S. Thesis Presentation by Brad Butcher
Thursday, October 10, 2002

(Dr. Stephen Dickerson, advisor)

"A Pneumatically-Powered Motion System for a High-Speed Scanner"


This thesis explains how an accurate motion system for a linear scanner can be built in a cost-effective manner through the employment of two pneumatic pistons, two air bearings, and a microcontroller. The design intent of this motion system is to carry a sensor (the weight of which when combined with the scanning head does not exceed 0.907 kg (2 lbm)) in a linear motion up to 5 m/s while exhibiting a repeatability of movement in the directions perpendicular to the scanning motion of ±2 µm.

This is demonstrated using entirely commercial components. Air bearings are used to support the scanner head, and pneumatic pistons are used to provide controlled back and forth pushes of the scanner head such that the head glides at a constant velocity along the middle 32 cm segment of the 46 cm scanning path. The air gap of the air bearings restrict movement in the direction perpendicular to the scanning velocity to within the desired tolerance, and the speed of the scanner head is controlled using a model predictive control scheme run on a Motorola MC68HC11E9 microcontroller.

Engineering analysis is used to show that the technology demonstration can be extended to achieve the scanner objectives.