Adaptive Fuzzy Fixed-Time Control for Uncertain Nonlinear Systems with Input Saturation and External Disturbances
- 1College of Electrical and Information Engineering, Changchun Institute of Technology, Changchun 130012, China
- 2School of Electronics and Information Engineering, Changchun University of Science and Technology, Changchun 130022, China
Abstract
This study addresses the fixed-time tracking control of a class of uncertain strict-feedback nonlinear systems, where the nonlinear drift functions and external disturbances are unknown, while the control-gain functions are assumed to be known smooth functions with known signs and positive bounds. The systems are additionally subject to actuator saturation. A smooth hyperbolic-tangent model is employed to represent the saturation characteristic. On this basis, the mean-value theorem is utilized to obtain an equivalent input representation containing an unknown control effectiveness coefficient. The resulting saturation approximation error is incorporated with the external disturbance to construct a compound disturbance. In the backstepping framework, unknown nonlinearities are handled through fuzzy basis-function modeling, whereas adaptive mechanisms and smooth robust compensators are designed to mitigate the influence of approximation errors and lumped disturbances. A fixed-time command filter is introduced to eliminate the need for successive differentiation of virtual control laws, thereby reducing the computational complexity associated with conventional backstepping. Moreover, a bi-power compensator is introduced to reduce command-filter-induced errors while retaining fixed-time performance. The combined use of different-power feedback terms ensures practical fixed-time stability, with all closed-loop variables bounded and the tracking, compensation, and estimation errors driven into a prescribed neighborhood within an initial-condition-independent settling time. Simulations on a nonlinear damped car with symmetric/asymmetric saturation and time-varying disturbances confirm the tracking and disturbance-rejection performance of the proposed method.
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BibTeX
@article{li2026adaptive,
title = {{Adaptive Fuzzy Fixed-Time Control for Uncertain Nonlinear Systems with Input Saturation and External Disturbances}},
author = {Linlin Li and Yuhao Xing and Ying Ma},
journal = {Mathematics},
year = {2026},
month = oct,
doi = {10.3390/math14203648},
url = {https://www.mdpi.com/2227-7390/14/20/3648},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Adaptive Fuzzy Fixed-Time Control for Uncertain Nonlinear Systems with Input Saturation and External Disturbances
AU - Linlin Li
AU - Yuhao Xing
AU - Ying Ma
PY - 2026
DA - 2026/10/09
JO - Mathematics
DO - 10.3390/math14203648
UR - https://www.mdpi.com/2227-7390/14/20/3648
AB - This study addresses the fixed-time tracking control of a class of uncertain strict-feedback nonlinear systems, where the nonlinear drift functions and external disturbances are unknown, while the control-gain functions are assumed to be known smooth functions with known signs and positive bounds. The systems are additionally subject to actuator saturation. A smooth hyperbolic-tangent model is employed to represent the saturation characteristic. On this basis, the mean-value theorem is utilized to obtain an equivalent input representation containing an unknown control effectiveness coefficient. The resulting saturation approximation error is incorporated with the external disturbance to construct a compound disturbance. In the backstepping framework, unknown nonlinearities are handled through fuzzy basis-function modeling, whereas adaptive mechanisms and smooth robust compensators are designed to mitigate the influence of approximation errors and lumped disturbances. A fixed-time command filter is introduced to eliminate the need for successive differentiation of virtual control laws, thereby reducing the computational complexity associated with conventional backstepping. Moreover, a bi-power compensator is introduced to reduce command-filter-induced errors while retaining fixed-time performance. The combined use of different-power feedback terms ensures practical fixed-time stability, with all closed-loop variables bounded and the tracking, compensation, and estimation errors driven into a prescribed neighborhood within an initial-condition-independent settling time. Simulations on a nonlinear damped car with symmetric/asymmetric saturation and time-varying disturbances confirm the tracking and disturbance-rejection performance of the proposed method.
SN - 2227-7390
ER -