Adaptive compensation of persistent actuator failures of nonlinear systems

Abstract

Summary In this article, adaptive compensation designs are developed for nonlinear systems with uncertainties from the system functions and persistent actuator failures of characterizations that (i) some unknown system inputs are stuck at some unknown fixed or varying values at unknown time instants and (ii) the failure pattern always switches from one to another and the switching does not stop. Such a controlled plant is described by an uncertain time‐varying nonlinear system, and some robust adaptive feedback linearization based failure compensation results are studied for closed‐loop system stabilization and bounded output tracking for some specific conditions. To improve the tracking performance in the presence of persistent actuator failures, a new adaptive control scheme is developed, using the failure indicator function which contains the failure pattern and failure time in the formulation. Detailed stability and tracking performance are shown. Simulation results are shown to verify the effectiveness of the proposed adaptive actuator failure compensation method.

Adaptive compensation control of nonlinear systems with unknown actuator failures

“…Following the same analysis, 38 it can be obtained that all signals of the closed-loop system are globally uniformly bounded for all t ≥ 0. Then, it is clear from (45) that (|z j | − 𝛿 j ) 𝜌+1−j f j ∈ L 2 , and from ( 29), (35), (39), (41), we have d[(|z j |−𝛿 j ) 𝜌+1−j f j ] dt ∈ L ∞ . Thus, we can obtain that lim t→+∞ (|z j (t)| − 𝛿 j ) 𝜌+1−j f j = 0 by using Barbalat's lemma, which implies that z 1 converges to [−𝛿 1 , 𝛿 1 ] asymptotically.…”

“…Remark The actuator failure model (2) can be used to closely approximate a large class of practical failures, by a proper selection of these basic functions $$$ {f}_{jlh}(t) $$$, while parametrized by $$$ {\overline{d}}_{jlh} $$$. This kind of parameterized failure model has been applied in many literature, such as References 11,12,34‐36. Compared with Reference 37, the failure model used in our article contains more fault information.…”

Control of a MIMO Coupled Plant Using a Neuro-Fuzzy Adaptive System Based on Boolean Relations

“…Another important aspect is concerning to the sensor and actuator failures, which can cause intermittent fault, system performance deterioration, and even damages. To solve the uncertain actuator failure issues, different control techniques were proposed, where adaptive control based failure compensation designs are a suitable option [15].…”