The semi-online robotic pallet loading problem

Abstract

The distributor’s online pallet loading problem (DPLP), which involves efficiently packing a set of cuboid boxes with various dimensions and unknown order into a minimum number of given sized pallet, is extensively employed in industrial automation and has recently garnered significant attention from the research community. However, the existing online approaches face challenges due to the unpredictable arrival order of boxes and the requirement for fast processing. To address this issue, we introduce a new variant of DPLP, the online pallet loading problem with buffer area, by introducing a buffer area with a predefined capacity within the stacking region. The arrival boxes are initially positioned within the buffer area until the total number of boxes reaches the maximum capacity of the buffer area, then, the boxes in the buffer area are selected and packed into the pallet. We propose a greedy search heuristic to solve the online DPLP with buffer area. Our approach uses an open space approach to represent the residual space and combine simple and guillotine blocks to generate blocks. By minimizing the amount of waste, we select the appropriate box placement. Extensive experimental tests on classical and practical instances shows that our method improves pallet utilization by more than 15% compared to purely online algorithms. Compared with other state-of-the-art algorithms, our method improves the average improvement by 8%. Moreover, our approach exhibits a certain level of generalizability and holds substantial practical value for real-world applications.