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This paper concerns with the tracking control problem of a class of unknown nonlinear time-delay systems in the presence of output delay and inaccessible states. To deal with the difficulties arising from unmeasurable states, a fuzzy logic observer based on delayed outputs is firstly employed. Then, based on the delayed output, observed states and filtered virtual control signals, proper change of coordinates is defined for the purpose of designing dynamic surface control. By introducing appropriate Lyapunov-Krasovskii functionals in the design procedures, a controller and adaptation laws are obtained for the control strategy of nonlinear systems subject to output delay. Moreover, by selecting design parameters and matrices based on the acquired stability criteria, it is proved that the proposed adaptive fuzzy dynamic surface output feedback control approach is able to guarantee the uniformly ultimately boundedness of all the signals in the closed loop unknown nonlinear output-delay systems. Finally, the theoretic achievements are applied to three well-known benchmark systems to illustrate the effectiveness and efficiency of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper is focused on the decentralized tracking control problem of nonlinear large-scale systems with immeasurable states and unknown nonlinearities in each subsystems and their interconnections in the presence of unknown interconnection delays and uncertain input delays. To deal with inaccessible states and unknown nonlinearities, a fuzzy state observer is firstly constructed. Then, appropriate changes of coordinates are defined to cope with the problem of uncertain input delays and design dynamic surface control strategy for unknown nonlinear interconnected systems. In the design procedures, appropriate Lyapunov–Krasovskii functions are introduced to conquer the difficulties arising from interconnection delays with unknown upper bounds. it is also proven that the proposed method can ensure that all signals of the closed loop large-scale systems in the presence of both interconnection and input delays which have not been considered in previous literature are uniformly ultimately bounded. Furthermore, by appropriate selection of design parameters and matrices, the observation errors as well as the tracking errors converge to small desired values. Finally, to illustrate the effectiveness and efficiency of the proposed decentralized control scheme, numerical simulations are performed. [ABSTRACT FROM AUTHOR]

In this paper, the position and force tracking control problem of cooperative robot manipulator system handling a common rigid object with unknown dynamical models and unknown external disturbances is investigated. The universal approximation properties of fuzzy logic systems are employed to estimate the unknown system dynamics. On the other hand, by defining new state variables based on the integral and differential of position and orientation errors of the grasped object, the error system of coordinated robot manipulators is constructed. Subsequently by defining the appropriate change of coordinates and using the backstepping design strategy, an adaptive fuzzy backstepping position tracking control scheme is proposed for multi-robot manipulator systems. By utilizing the properties of internal forces, extra terms are also added to the control signals to consider the force tracking problem. Moreover, it is shown that the proposed adaptive fuzzy backstepping position/force control approach ensures all the signals of the closed loop system uniformly ultimately bounded and tracking errors of both positions and forces can converge to small desired values by proper selection of the design parameters. Finally, the theoretic achievements are tested on the two three-link planar robot manipulators cooperatively handling a common object to illustrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]