Dynamic task scheduling for robotic pick-and-place systems using sequential planning with a decision horizon
Więcej
Ukryj
1
Department of Production Engineering and Management, Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
Autor do korespondencji
Kamil Krot
Department of Production Engineering and Management, Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
SŁOWA KLUCZOWE
DZIEDZINY
STRESZCZENIE
This paper presents a comparative analysis of algorithms for planning the pick sequence in a robotic sorting process involving objects moving on a conveyor belt. The primary objective was to determine the effects of decision-horizon length on computation time and solution quality and to evaluate the effects of conveyor speed and the number of sorted classes on capture rate (CR). A custom simulation environment was developed in Python using a simplified kinematic model of a delta robot. The analysis included exhaustive search, Branch-and-Bound, a time-bounded Monte Carlo method, and the FIFO, SPT, and NNF heuristics. Under the investigated conditions, factorial growth limited the computationally feasible exhaustive-search horizon to seven objects, whereas B&B extended exact planning to 13 objects with a computation time of 1.53 s. Monte Carlo was evaluated over 100 independent runs per horizon using a 1 s computation-time budget. All 700 runs achieved the same maximum number of seven successful picks as B&B, although the probability of reproducing the complete B&B optimum generally decreased for longer horizons. For the 20-object horizon, the mean and maximum increases in sequence execution time were 4.12% and 6.47%, respectively, while the planning time decreased from 27.29 s for B&B to 1 s for Monte Carlo. In the experiment comprising 5,000 objects, B&B achieved the highest CR in 38 of the 56 scenarios, whereas FIFO and SPT achieved the same or higher CR under lower process loads. These results provide a basis for selecting the planning algorithm according to the decision horizon and current process conditions.