Direct Adaptive Fuzzy Tracking Control Research Articles

Adaptive fuzzy control for full states constrained systems with nonstrict-feedback form and unknown nonlinear dead zone

This paper addresses the problem of direct adaptive fuzzy tracking control design for a class of uncertain nonstrict-feedback systems with nonlinear dead zone and full state constraints. Fuzzy logic systems are used to approximate some unknown nonlinear functions and less adjustable parameters are adopted in each backstepping design process. This advantage is first to take into account the full state constrained nonstrict-feedback systems with input dead zone nonlinearity. To guarantee that the full state constraints are not violated, a novel adaptive fuzzy controller is developed by introducing Barrier Lyapunov Function with the error variables. Furthermore, it is proved that all the closed-loop signals remain semi-globally uniformly ultimately bounded and the tracking error converges to a small neighborhood of the origin. Two simulation examples are provided to verify the effectiveness of the proposed control method.

Direct Adaptive Fuzzy Tracking Control of Marine Vehicles With Fully Unknown Parametric Dynamics and Uncertainties

In this brief, a novel direct adaptive fuzzy tracking control (DAFTC) scheme for marine vehicles with fully unknown parametric dynamics and uncertainties is proposed. The significant contributions of the DAFTC approach are as follows. First, in the backstepping framework, fully unknown parametric dynamics and uncertainties are encapsulated into a lumped nonlinearity function encompassing system states and virtual control signals. Second, the integrated nonlinearity function is further identified online by an adaptive fuzzy approximator that synthesizes a model-free control scheme (termed DAFTC) without requiring any a priori knowledge of the model. Third, tracking errors are proven to be uniformly ultimately bounded (UUB) and can converge to an arbitrarily small neighborhood of zero in a finite time. Simulation studies and comprehensive comparisons demonstrate that the proposed DAFTC scheme has remarkable performance and is superior in both tracking accuracy and unknown parametric dynamics compensation.

Robust adaptive fault-tolerant control for a class of uncertain nonlinear systems with multiple time delays

This study is concerned with the problem of robust adaptive fuzzy fault-tolerant control for a class of uncertain nonlinear systems with mismatching parameter uncertainties, external disturbances, multiple state time delays perturbations and actuator failures, which include loss of effectiveness, outage and stuck modes. A novel direct adaptive fuzzy tracking control scheme is developed to achieve the fault-tolerant control objective. First, by introducing a positive nonlinear control gain function, the effects of state time delays and actuator failures are effectively compensated. Then, a suitable fuzzy logic system (FLS), which is used to approximate the corresponding nonlinear function, is constructed to eliminate the influences on mismatched parameter uncertainty and external disturbance. Moreover, it is shown that all the closed-loop system signals are uniformly bounded and that the tracking error converges to a small neighborhood of the origin via Lyapunov–Krasovskii stability analysis. Finally, the proposed adaptive fuzzy fault-tolerant tracking design approach is illustrated on a two stage chemical reactor system with delayed recycle streams.

Adaptive fault-tolerant control of a class of nonaffine nonlinear systems with mismatched parameter uncertainties and disturbances

This paper studies the problem of robust adaptive fuzzy fault-tolerant tracking control for a class of nonaffine nonlinear systems with mismatched parameter uncertainties, external disturbances and actuator faults. Without using complicated backstepping technique, a direct adaptive fuzzy tracking control approach is used to achieve the fault-tolerant control objective. First, to overcome the obstacle for the nonaffine nonlinear term with actuator faults, a nonaffine compensation term is constructed to eliminate the effect of the nonaffine fault parameters. Then, based on the implicit function theorem and the mean value theorem, a novel design scheme that converts the nonaffine system into the corresponding affine system is developed, and two effective fuzzy logic systems, which are introduced to approximate the appropriate nonlinear functions, are constructed to compensate the effect on mismatched parameter uncertainty and disturbance, respectively. Furthermore, with the help of Lyapunov stability analysis, it is also proved that all the closed-loop system error signals are uniformly ultimately bounded. Finally, a numerical example is given to verify the efficiency of the presented adaptive fuzzy fault-tolerant tracking design approach.

Adaptive Fuzzy Tracking Control of a Class of Stochastic Nonlinear Systems with Unknown Dead-Zone Input

In this paper, a direct adaptive fuzzy tracking control scheme is presented for a class of stochastic uncertain nonlinear systems with unknown dead-zone input. A direct adaptive fuzzy tracking controller is developed by using the backstepping approach. It is proved that the design scheme ensures that all the error variables are bounded in probability while the mean square tracking error becomes semiglobally uniformly ultimately bounded (SGUUB) in an arbitrarily small area around the origin. Simulation results show the effectiveness of the control scheme.

Direct Fuzzy Tracking Control of a Class of Nonaffine Stochastic Nonlinear Systems with Unknown Dead-Zone Input

In this paper, a direct adaptive fuzzy tracking control scheme is presented for a class of stochastic nonaffine uncertain nonlinear systems with unknown dead-zone input. Based on the first-type fuzzy logic system's online approximation capability, a direct adaptive fuzzy tracking controller is developed by using the backstepping approach. It is proved that the design scheme ensures that all the error variables are bounded in probability while the mean square tracking error becomes semiglobally uniformly ultimately bounded(SGUUB) in an arbitrarily small area around the origin. Simulation results show the effectiveness of the control scheme.

Direct adaptive fuzzy tracking control for a class of perturbed strict-feedback nonlinear systems

In this paper, a novel direct adaptive fuzzy tracking control scheme is presented for a class of perturbed strict-feedback nonlinear systems with unknown virtual control coefficients. Based on the Mamdani-type fuzzy logic system online approximation capability, a direct adaptive fuzzy tracking controller is developed by using the backstepping approach. The proposed design scheme guarantees that all the signals in the resulting closed-loop system are uniform ultimate bounded, and the tracking error converges to an arbitrarily small neighborhood of the origin. In addition, the number of the online adaptive parameters is not more than the order of the considered system and the possible controller singularity problem is removed by introducing the modified integral Lyapunov functions. Finally, two simulation examples are used to demonstrate the effectiveness of the proposed control scheme.