Adaptive control for rejecting disturbances with time-varying frequencies in tape systems

In this paper, we present two adaptive algorithms for tape systems that account for tape tension ripples. Tape tension ripples are caused by reel eccentricities that produce disturbances with time-varying frequencies. In both designs, the frequency and the magnitude of the disturbance are estimated to synthesize an input signal to cancel the disturbance. In the first design, by adjusting the values of the adaptive parameters that are related to the frequency of the disturbance, the estimated frequency reflects the time-varying nature of the disturbance. The second design extends an existing digital adaptive feed-forward cancellation scheme used in hard disk drives for application to tape tension control problems. For both designs, time-varying sinusoidal disturbance signals are used in simulations to analyze and evaluate the performances of the developed adaptive control methods on a model of a tape system.