Optimal Trajectory Planning For Material Handling of Compliant Sheet Metal Parts

One of the most critical issues in the material handling of compliant objects is excessive part deformation. The deformation of compliant sheet metal parts during the handling process can significantly impact both part dimensional quality and production rate. Increasing production rate while maintaining part quality requires an optimal design of the part transfer trajectory. This paper describes a new methodology of time-optimal trajectory planning for compliant parts by discretizing the part transfer path into N segments that have equal horizontal distance and by approximating the trajectory as having piecewise constant acceleration that can only change its value at the end of each segment. The contribution of the methodology is that part deformation determined by transfer velocity and acceleration is considered as a nonlinear constraint, which is obtained from FEA simulation and model fitting. Part permanent deformation, trajectory smoothness, and static obstacle avoidance are also considered. The methodology is validated by simulations at different motion conditions and obstacle configurations. This paper addresses the lack of current design guidelines for material handing development and simultaneously provides a mathematical tool to significantly enhance the production efficiency in manufacturing of compliant sheet metal parts.