ADAPTIVE FUZZY TRACKING CONTROL FOR A CLASS OF PERTURBED NONLINEAR TIME-VARYING DELAYS SYSTEMS WITH UNKNOWN CONTROL DIRECTION

2013 ◽  
Vol 21 (04) ◽  
pp. 497-531 ◽  
Author(s):  
HONGYUN YUE ◽  
JUNMIN LI
Keyword(s):  
Controller Design ◽  
Adaptive Fuzzy Control ◽  
Small Neighborhood ◽  
Design Procedure ◽  
Time Varying ◽  
Adaptive Fuzzy ◽  
Control Scheme ◽  
Unknown Control ◽  
Unknown Control Direction ◽  
Control Direction

An adaptive fuzzy control scheme with only one adjusted parameter is developed for a class of nonlinear time-varying delays systems. Three kinds of uncertainties: time-varying delays, control directions, and nonlinear functions are all assumed to be completely unknown, which is different from the previous work. During the controller design procedure, appropriate Lyapunov-Krasovskii functionals are used to compensate the unknown time-varying delays terms and the Nussbaum-type function is used to detect the unknown control direction. It is proved that the proposed controller guarantees that all the signals in the closed-loop system are bounded and the tracking errors converge to a small neighborhood around zero. The two main advantages of the developed scheme are that (i) by combining the appropriate Lyapunov-Krasovskii functionals with the Nussbaum-gain technique, the control scheme is proposed for a class of nonlinear time-varying delays systems with unknown control directions, (ii) only one parameter needs to be adjusted online in controller design procedure, which reduces the computational burden greatly. Finally, two examples are used to show the effectiveness of the proposed approach.

scholarly journals Tracking Control Strategy Using Filter-Based Approximation for the Unknown Control Direction Problem of Uncertain Pure-Feedback Nonlinear Systems

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1341
Author(s):  
Yun Ho Choi ◽  
Sung Jin Yoo
Keyword(s):  
Controller Design ◽  
Tracking Error ◽  
Design Procedure ◽  
Control Input ◽  
State Variables ◽  
Feedback Systems ◽  
Unknown Control Directions ◽  
Unknown Control ◽  
Unknown Control Direction ◽  
Control Direction

A filter-based recursive tracker design approach is presented for the problem of unknown control directions of pure-feedback systems with completely unknown non-affine nonlinearities. In the controller design procedure, the first-order filters for error surfaces, a control input, and state variables are employed to design nonadaptive virtual and actual control laws independent of adaptive function approximators. In addition, for the unknown control direction problem, the filtering signals are incorporated with Nussbaum functions. Different from existing adaptive approximation-based control schemes in the presence of unknown control directions, the proposed approach does not require any adaptive technique regardless of completely unknown nonlinear functions. Therefore, a simplified tracking structure can be constructed. Using the Lyapunov stability analysis, it is shown that the tracking error is reduced within an adjustable neighborhood of the origin while ensuring all the closed-loop signals are bounded.

Sign in / Sign up

Export Citation Format

Share Document