On the gain scheduling for networked PI controller over IP network

The potential use of networks for real time-time high performance control and automation is enormous and appealing. Replacing a widely used PI controller by a new networked controller for networked control capability can be costly and time-consuming. This paper proposes a methodology based on gain scheduling with respect to real-time IP traffic conditions to enhance the existing PI controller so it can be used over IP networks with a general network protocol like Ethernet. This paper first describes the gain scheduling approach based on constant network delays using a rational function approach. The formulation is extended to random IP network RTT (round trip time) delays by using the generalized exponential distribution model. Simulation results show that the PI controller with gain scheduling provides significantly better networked control system performance.