Generation of feasible gripper trajectories in automated composite draping by means of optimization

Abstract

Prepreg composites find great applicability in e.g. the automotive and aerospace industries. A major challenge with this class of material systems is the accurate placement of a fabric that can be very tacky and hence sticks to the mold surface. In this study, automatic draping of entire plies of woven prepregs is considered. A robot end effector with a grid of actuated grippers is under development and it has the ability to position the plies onto double-curved mold surfaces of low curvature. The key issue is how the grippers of the end effector should move to achieve successful drapings of the plies that meet the quality requirements of the industry. In this study, an approximate ply model based on cables with bending stiffness is applied in an optimization framework where the gripper movements constitute the design variables. The optimization framework has taken inspiration from manual layup procedures. The numerical draping results indicate the usefulness of the cable model used in connection with the optimization framework. The next step is to implement the generated gripper trajectories on the physical robot system.

Keywords

• woven prepreg
• draping
• trajectory optimization
• offline motion planning
• automation