Bilevel Trajectory Optimization for Vacuum-Based Pick-and-Place Operations: A Numerical Study

Motion optimization has a significant influence on performance and robustness of modern robotic handling systems. In this study, a pick-and-place operation, as can be found in many processing machines, serves as a representative use case to develop a novel method for motion optimization. Based on optimal control theory, the introduced method uses bilevel optimization simultaneously addressing process stability, favorable dynamic behavior and practical applicability. A process model for gripper load estimation established in the literature serves both as a basis for optimization and for evaluating the solution found. To establish a benchmark, a spline-based trajectory is generated. As this work proposes a theoretical approach, simulations based on the retrieved model serve as an evaluation basis of the resulting trajectories. The results show that a significant reduction in gripper load by approximately 60% was achieved compared to the reference motions. Eventually, requirements and limitations for application of the new method are discussed.