Observer-Based Adaptive Fault-Tolerant Tracking Control of Nonlinear Nonstrict-Feedback Systems

Abstract

This paper studies an output-based adaptive fault-tolerant control problem for nonlinear systems with nonstrict-feedback form. Neural networks are utilized to identify the unknown nonlinear characteristics in the system. An observer and a general fault model are constructed to estimate the unavailable states and describe the fault, respectively. Adaptive parameters are constructed to overcome the difficulties in the design process for nonstrict-feedback systems. Meanwhile, dynamic surface control technique is introduced to avoid the problem of "explosion of complexity". Furthermore, based on adaptive backstepping control method, an output-based adaptive neural tracking control strategy is developed for the considered system against actuator fault, which can ensure that all the signals in the resulting closed-loop system are bounded, and the system output signal can be regulated to follow the response of the given reference signal with a small error. Finally, the simulation results are provided to validate the effectiveness of the control strategy proposed in this paper.

Finite‐time prescribed performance adaptive fuzzy fault‐tolerant control for nonstrict‐feedback nonlinear systems

“…As the function j ( ) contains the whole state variables, system (14) is called to be in nonstrict-feedback structure, which is different from the strict-feedback form in the works of Huo et al 24 and Sun et al, 25 where the state variables i (i = j + 1, … , n) are not contained in the nonlinear function j ( ). Although, some adaptive fuzzy control methods have been proposed for nonstrict-feedback systems, 47,48 these existing research results are developed under the condition that the time variable tends to be infinite. Unlike the existing works, a finite-time adaptive fuzzy control scheme is investigated for nonstrict-feedback nonlinear system subject to actuator faults.…”

“…Combining (64)-(65) with (63) produces Remark 5. Note that several backstepping-based adaptive fuzzy control methods have been developed in the works of Sun et al, 40 Wang et al, 47 and Wu et al 48 for nonstrict-feedback nonlinear systems. The main differences between our result and the ones in the aforementioned works 40,47,48 lie in the following.…”

“…1) Prescribed performance issues are not considered for the developed systems in the aforementioned works, 40,47,48 the control scheme designed in the work of Sun et al 40 depends on the operating conditions without actuator faults, and the proposed methods in the works of Wang et al 47 and Wu et al 48 are investigated in the sense of infinite time stability. In this paper, not only the nonlinear system under study is more general but also the finite-time prescribed performance control issue is taken into account.…”

“…2. Compared with the existing works on nonstrict-feedback systems in the works of Wang et al 47 and Wu et al, 48 where the infinite time control problems are mainly taken into consideration, and in this paper, by designing performance function, the system output is ensured to be within the specified range in finite time. Therefore, conventional adaptive fuzzy control schemes cannot be directly used for the finite-time control issue in our paper.…”

Robust Decentralized Adaptive Fuzzy Control of Large‐Scale Nonaffine Nonlinear Systems With Strong Interconnection and Application to Automated Highway Systems

“…In recent years, control system design for complex nonlinear systems has attracted considerable attention in the control community. Outstanding results in this area have been emerging, including adaptive backstepping controllers for state constraint systems [1,2], adaptive fuzzy or neural controllers for uncertain systems [3][4][5][6][7][8] and adaptive controllers for stochastic nonlinear systems [9,10]. These studies are conducted for systems in affine form.…”