Class Of Nonstrict-feedback Systems Research Articles

Adaptive neural dynamic surface control for nonstrict feedback systems with state delays

AbstractThis article focuses on a class of nonstrict feedback systems with input delay, state delays and time‐varying full‐state constraints by proposing an adaptive neural control scheme. To overcome the problems of all state variables effected by time‐varying constraints, the asymmetric time‐varying barrier Lyapunov functions are constructed. The influence of state delays and input delay is eliminated by employing suitable Lyapunov–Krasovskii functionals. Additionally, the process of controller design is based on backstepping method and the unknown functions can be approximated by radial basis function neural networks. Moreover, the problem of repeated differentiations for nonlinear components during controller design is hugely simplified by taking advantage of the dynamic surface control method. The boundness of all the closed‐loop signals can be ensured by the designed controller. Finally, two numerical simulations illustrate that the proposed adaptive neural control scheme is effective.

Fast Finite-Time Fuzzy Control for a Class of Nonstrict Feedback Systems with Input Quantization

Fast Finite-Time Fuzzy Control for a Class of Nonstrict Feedback Systems with Input Quantization

Fuzzy adaptive event-triggered output feedback control for nonlinear systems with tracking error constrained and unknown dead-zone

ABSTRACT In this paper, an adaptive fuzzy event-triggered output feedback control scheme is studied for a class of non-strict feedback systems with tracking error constrained and unknown dead-zone. Fuzzy logical systems (FLSs) are employed to solve the uncertainties of the controlled plant, and the immeasurable states are estimated by employing the fuzzy observer. In the designed observer, to compensate for the effect of unknown dead-zone by invoking the known designed event-triggered input signal, an adaptive parameter is designed. Furthermore, due to event-triggered control (ETC) places a great burden on the computing space, the dynamic surface control (DSC) technique is used to solve the problem of ‘explosion of complexity’ in each step, and the simplified barrier Lyapunov function (SBLF) is utilised to restrict the tracking error within the prescribed boundaries. Consequently, the designed parameter adaptive laws and event-triggered controller can ensure that all signals of the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB). Ultimately, two numerical simulation examples are provided to illustrate the effectiveness of the proposed event-triggered control theory.

Adaptive Dynamic Surface Fuzzy Control for State Constrained Time-Delay Nonlinear Nonstrict Feedback Systems With Unknown Control Directions

This article proposes an adaptive dynamic surface fuzzy control method for a class of nonstrict feedback systems. The systems are subject to state constraints with unknown control directions, time-delay, and external disturbances. The problem of unknown control direction is solved by using the Nussbaum gain technique, and the effect of unknown delay which is time varying is eliminated by introducing compounding type Lyapunov function. Furthermore, based on the fuzzy backstepping method, an adaptive tracking controller is constructed which guarantees that the constrained states are not violated while all the closed-loop trajectory signals remain bounded. The effectiveness of the obtained results is illustrated via simulations.

Some new results on the finite-time control and its application to a chemical reactor system

In this paper, a novel finite-time control scheme is proposed for a class of non-strict feedback systems with guaranteed preassigned output tracking performance. First, a finite-time convergent performance function is proposed in the prescribed performance control structure. Then, based on the proposed performance function, a finite-time stable controller is devised. Compared with the existing finite-time control schemes, the fractional state or output information and discontinuous phenomenon is avoided totally. Finally, application to a chemical reactor system is organized to validate the effectiveness of the proposed control scheme.

Active vibration control of underactuated free-floating spacecraft via a performance enhanced way

This paper investigates an enhanced prescribed performance control approach for the postcapture active vibration suppression of the underactuated free-floating spacecraft via only using the output information. First, an enhanced performance function is developed to quantitatively characterize the transient and steady-state vibration responses. Then, based on the performance function, an output-feedback prescribed performance controller along with an adaptive nonlinear filter is devised to eliminate the vibration within arbitrarily specified time. Compared with the existing works, the primary advantage is that the convergence time of the vibration system can be offline preassigned arbitrarily by the users. In the meanwhile, the proposed control scheme can be directly extended to a class of nonstrict feedback systems. Finally, applications to the underactuated free-floating spacecraft are employed to validate the effectiveness of the proposed enhanced prescribed performance control approach.