Dynamic modelling and control simulation of automatically dispensed adhesive beads

The authors describe modeling and control strategies for the adhesive dispensing process. To ensure the reliability of structural adhesive joints, the dispensed adhesive needs to be consistent. The consistency is a function of the amount of dispensed material and its displacement. The dispensed material is controlled through a closed-loop system which is built around a six-axis robot carrying a digitally controlled dispensing gun, a single-axis linear table carrying the workpiece and a computer vision system for online inspection and image processing. The bead parameters obtained by image processing are used by the controller to ensure that the bead stays in the desired bandwidth. The process has a long delay due to the transportation lag and the time taken for image processing. It can be analyzed as lumped parameter dynamics with a pure delay which is a function of the operating condition. The simulation of the controller and its performance are discussed