Stability-Guaranteed Scheduling for Mesh Networked Control Systems with Fine-Grained Timing

As industrial control applications scale up, mesh networked control systems (MNCSs) are gaining popularity, where multiple control loops share a multi-hop mesh network. However, these loops often suffer from long-span, time-varying delays caused by the multi-hop transmissions of multiple flows, which significantly degrade control performance, particularly stability. Existing studies on delay-aware stability conditions are usually independent with network scheduling, leading to a pessimistic stability analysis. Meanwhile, existing stability-aware scheduling approaches rely on coarse-grained designs, further worsening stability guarantees and limiting network capacity. In this work, we propose a stability-guaranteed scheduling mechanism for MNCSs with fine-grained timing. We first establish a stability condition that accounts for time-varying delays over an extended horizon spanning multiple superframes, which reduces the pessimism in stability analysis and enables more refined scheduling strategies. Based on this condition, We design a Long time-horizon and Fine-grained network scheduling mechanism with Stability Guarantee (LFSG), which deterministically maps the stability condition into the fine-grained network scheduling, considering fluctuating delays over the extended horizon. Furthermore, we provide a stability-capacity-aware LFSG (SCA-LFSG), which aims to maximize the number of stabilizable control loops and demonstrates its effectiveness through various application paradigms. Extensive studies demonstrate the advantages of stability analyses, LFSG, and SCA-LFSG over state-of-the-art approaches in terms of both control and timing performance.