PI parameterization using adaptive fuzzy modulation (AFM) for networked control systems. I. Partial adaptation

When using an IP network in control systems, a network-induced time delay is generated, which has adverse effects on the networked closed-loop control systems such as performance degradation and system destabilization. In this paper, we propose an intelligent controller using fuzzy logic on top of a PI gain to adaptively compensate for the IP network-induced time delay in time-delay sensitive networked control system (NCS) applications. One of the advantages of this proposed fuzzy logic compensator is that we do not need to completely redesign the existing PI controller, but simply modulate the PI controller action with the output of the intelligent fuzzy logic controller. In part I of this paper, a partial adaptation scheme to tune the consequent parameters for this fuzzy logic modulator is presented. Numerical simulation of a network-based controlled DC motor is used to illustrate the effectiveness of the proposed scheme over a direct PI controller parameter tuning. In part II of this paper, we propose the full adaptive fuzzy modulation (AFM), where both consequent parameters and membership functions parameters are tuned adaptively.