The application of modern control theory to a textile winder for acetate and other fine filaments in which the tension variations must be kept to a minimum is described. It has proved possible to extend the operational speed from 800 to 2000 m min - 1 with substantially reduced tension variations. Previous attempts to operate at higher speeds caused increased tension variations. A new drive system with fuzzy control and a synchronised compensator has been incorporated in the system to achieve these results. A low-displacement, high-bandwidth filament tension sensor has been developed as an integral part of the system.