Trajectory Planning for Interactive Pick-and-Place Operations of Delta Robots

Robots often need to interact with environment while performing operation tasks. In this article, an interactive pick-and-place operation (PPO) trajectory planning method with adjustable interaction point is proposed for Delta robot to realize the flexible operation. First, the kinematics of Delta robot is briefly introduced. Then, by using the characteristics of Pythagorean-Hodograph (PH) curve, the interactive pick-and-place operation path (PPOP) is designed on the basis of the general PPOP. Two different scenarios, where the interaction point is inside and outside the general PPOP, are investigated and analyzed. In particular, when the interaction point is inside the general PPOP, two different options are constructed to perform the PPO, one option is that the two PH curves form a J-shaped curve, and the other option is that the two PH curves form an S-shaped curve. In addition, the motion profile of the interactive PPOP is configured. Finally, the proposed method is verified by simulations and experiments, and the results show that the proposed method can achieve smooth motion, and the trajectory shape can be adjusted locally or globally by configuring the parameters according to the actual task, so different PPO trajectories can be realized to meet the requirements of various operating environments, thus improving the flexibility of the Delta robot system.