Modeling of Tension Control System with Passive Dancer Roll for Automated Fiber Placement

The fiber tension should be kept constant during the automated placement of fiber prepreg. The velocity of the fiber placement end-effector moving on complex aircraft panel mould surface varies rapidly, which greatly disturbs the precision of tension control. This paper proposes a tension control strategy combining active control and passive control. The pay-off motor controls the fiber tension directly and a passive dancer roll is designed theoretically as the equipment for attenuation of tension disturbance to realize the real-time compensation of low-frequency velocity variations. The nonlinear model of tension control system, which includes the dynamics of the passive dancer roll, is established, and the effect of dancer roll parameters on its disturbances attenuation performance is analyzed. The controller is designed using the H∞ mixed sensitivity method. An experimental tension control precision about 2% is obtained at stable placement speed on the automated fiber placement (AFP) machine. The experiments also indicated that the tension would not vary over 1 N at a maximum acceleration of 4 m/s2.