Frequency domain characterization of take-up reel air-entrainment in low-tension and high-speed tape transport

Air entrainment in tape spooling is important because it affects the tape stacking quality and the dynamics for which the transport controller must be designed Accurate estimates of the air film thickness between the layers of tape are difficult to obtain by direct measurement. In this paper, a new frequency domain method is presented where the length of the entrained air film is estimated by determining the spring constant of the unsupported tape span. Using multi-input single-output (MISO) frequency based system identification, the resonant frequency of the system associated with the longitudinal mode of the tape is derived. These data are compared to predictions from the well known nip height equation. The utility of these equations is discussed.