Stabilizing control of networks with uncertain time varying communication delays

Building a real-time (RT) control network using standard TCP/IP and Ethernet is often difficult, because the communication protocols usually have unpredictable time delays. When RT packets are transported within an ordinary Ethernet network, there may be a significant time delay before receiving them. This sometimes causes loop instability and performance degradation. A compensation scheme that consists of a fuzzy-PID controller and a neural network compensator is proposed here. This diminishes the influence from time delays on stability while maintaining the system performance. The proposed design is experimentally verified in the real-world network environment to show its effectiveness and applicability.