Robust Adaptive Fuzzy Control of Uncertain Nonlinear Systems with Unknown Dead-Zone

Abstract

This paper presents a robust adaptive fuzzy control scheme for a class of uncertain nonlinear systems containing an unknown dead-zone. Dead-zone characteristics are quite commonly encountered in actuators, such as hydraulic and pneumatic valves, electric servomotors, and electronic circuits, etc. Therefore, by using a description of a dead-zone and by exploring the properties of this dead-zone model intuitively and mathematically, a robust adaptive fuzzy control method is presented without constructing the dead-zone inverse. The unknown nonlinear functions of the controlled system are approximated by the fuzzy logic system according to some adaptive laws. By means of Lyapunov stability theorem, the proposed robust adaptive fuzzy control scheme can guarantee the robust stability of the whole closed-loop system with an unknown dead-zone in the actuator and obtain good tracking performance as well. Finally, an example and simulation results are illustrated to demonstrate the validity of the proposed method.

Robust adaptive control with unmodeled dynamics and unknown dead-zones

“…Define a smooth scalar function = 2 /2, then˙= . In view of Assumption 3, and using (14), (15) we obtaiṅ…”

“…For a dead-zone with equal slopes, robust adaptive control was developed for a class of nonlinear systems without constructing the inverse of the dead-zone in [14]. In [15], an adaptive stable problem for a class of SISO nonlinear systems with unknown dead-zones and unknown function control gain was considered. Using Nussbaum-type functions and fuzzy logic systems, a direct adaptive robust control was presented for a class of strict-feedback nonlinear systems with unmodeled dynamics and unknown virtual control directions in [16].…”

The Synthesis of Nonlinear Hyperstable Adaptive Control Systems of Multiple Connected Electric Drives of Robotic Technological Equipment for arc Plasma Coating

“…The requirement of simultaneous operation of all interconnected asynchronous valve electric drives is equivalent to reducing the system of differential equations [1][2][3][4] to multiple connected independent equations, each of which contains only generalized coordinates and their derivatives. This requirement can be realized by choosing the structure of ACS of electric drives and using dynamic decoupling techniques in the structure of electric drive transmissions.…”