Solving Integrated Process Planning and Scheduling Problem via Graph Neural Network Based Deep Reinforcement Learning
Hongpei Li, Han Zhang, Ziyan He, Yunkai Jia, Bo Jiang, Xiang Huang, Dongdong Ge
TL;DR
The paper tackles IPPS, an NP-hard problem that unifies process planning and shop scheduling. It introduces an end-to-end DRL framework that models IPPS as a Markov Decision Process and uses a heterogeneous graph neural network to capture complex relationships among operations, machines, and jobs, guided by PPO. Key contributions include proving MDP–IPPS equivalence (Theorem 1), introducing a combination-based action-space reduction to curb exploration, and designing a dense reward based on estimated end-times to stabilize learning. Empirical results on synthetic and public benchmarks show the approach achieves faster, higher-quality solutions than Greedy methods and remains competitive or superior to OR-Tools on large-scale instances, highlighting its potential for scalable, real-time IPPS in modern manufacturing. The work also demonstrates strong generalization capabilities and provides ablation evidence for the efficacy of reward design and graph representations.
Abstract
The Integrated Process Planning and Scheduling (IPPS) problem combines process route planning and shop scheduling to achieve high efficiency in manufacturing and maximize resource utilization, which is crucial for modern manufacturing systems. Traditional methods using Mixed Integer Linear Programming (MILP) and heuristic algorithms can not well balance solution quality and speed when solving IPPS. In this paper, we propose a novel end-to-end Deep Reinforcement Learning (DRL) method. We model the IPPS problem as a Markov Decision Process (MDP) and employ a Heterogeneous Graph Neural Network (GNN) to capture the complex relationships among operations, machines, and jobs. To optimize the scheduling strategy, we use Proximal Policy Optimization (PPO). Experimental results show that, compared to traditional methods, our approach significantly improves solution efficiency and quality in large-scale IPPS instances, providing superior scheduling strategies for modern intelligent manufacturing systems.
