Fuzzy sliding mode control with applications

In the present thesis, a Fuzzy Sliding Mode Control (FSMC) for second-order uncertain plants is proposed using equivalent control approach to improve performance of control systems. A fuzzy solution based Proportional + Integral + Derivative (PID) sliding surface, fuzzy switching gain and fuzzy boundary layer are used in the proposed solution algorithm. As a switching function hyperbaulic tangent function is used to eliminate chattering. Asymptotic stability is proved using direct Lyapunov stability approach. The performance of the closed-loop system is analyzed through an experimental application to an electromechanical plant to show effectiveness of the proposed fuzzy sliding-mode control and factors involved in the design. A dc motor system is chosen for the experimental applications since the dc motors are widely used in the industry in many applications that require position control and speed control. Experimental setup consists of a dc motor connected to a load and the motor drives a shaft that carries disks that operate various transducers, and a tachogenerator. The second-order nominal plant parameters are experimentally determined using input-output measured data. The results are presented to make a quantitative comparison with the sliding mode control (SMC) and PID control. It is demonstrated that the proposed FSMC system improves the performance of the closed loop system with better tracking specifications in the case of external disturbances, better behavior of the output and faster convergence of the sliding surface while maintaining the stability. Keywords: Electromechanical system model, fuzzy control, sliding mode control, fuzzy sliding mode control