Robust Takagi-Sugeno fuzzy control for systems with static nonlinearity and time-varying delay

In this paper, a robust Takagi-Sugeno fuzzy digital PID control methodology based on gain and phase margins specifications for SISO systems with nonlinearity and time-variant delay, is proposed. A multiobjective particle swarm optimization (PSO) strategy is defined to tune the fuzzy digital PID controller parameters, so the gain and phase margins specified to the fuzzy control system are get. Experimental results shown the efficiency of the proposed methodology for control of a thermal plant. The nonlinear static characteristic curves of this system was obtained from static testing thus suggesting its use to validate the results.