Coupling between the in-plane and lateral tape dynamics in high capacity linear tape transport systems

Abstract

Lateral tape motion (LTM) is defined as the lateral deviation of the tape from its prescribed strain-free state path. The effects of tape, roller, guide or reel imperfections on the LTM are reasonably well understood. Yet, the effects of disturbances in the longitudinal (in-plane) direction, which can couple into LTM, have not been well described. Longitudinal tape vibrations can be due to, but not limited to a) tension dynamics due to servo control of the tape reels, and/or tension impulses due to the unwinding of tape layers that experience sticking. The problem is further complicated due to the uncertainty of the tape length on the downstream side, as a result of the “floating layers” in the take-up reel. In this work, the equations of motion of the longitudinal and lateral tape motion are derived from first principles. The coupling due to non-linear longitudinal strain is considered. The equations of motion are solved by using the finite element method, and an explicit time integration algorithm. The entire tape path is modeled directly, where the interaction of the tape with the recording head and the guides are represented as concentrated forces, and moments. The effects of disturbances, typical for a tape transport system, on the coupling or lack there off are investigated.