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In this article, an adaptive consensus tracking control scheme is proposed for a class of high-order nonlinear multiagent systems with unknown control directions. Different from the existing results, the unknown control directions are not required to be identical and also unknown time-varying actuator faults are taken into account simultaneously. We design some novel Nussbaum functions and construct a monotonously increasing sequence in which the effects of our multiple Nussbaum functions reinforce rather than counteract each other. Moreover, some integrable auxiliary signals and a novel contradiction argument are introduced in the design and analysis. With these efforts, the obstacle jointly caused by the unknown control directions and actuator faults are circumvented, and the global stability of the overall closed-loop system and asymptotic convergence to zero of tracking errors are successfully achieved. Simulation results illustrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

In this paper, an output-feedback adaptive control scheme is proposed for a class of multi-input multi-output (MIMO) nonlinear systems, aiming at tolerating unknown actuator faults and unknown sensor faults simultaneously. The number of actuator faults is allowed be infinity, while the sensors may suffer from bias and gain variation all the time. By constructing an auxiliary filter and estimating the bounds of the fault uncertainties, the effects of the faults are successfully compressed. Also, the difficulty related to the high-frequency gain matrix is circumvented by introducing a matrix factorization and a similarity transformation. The proposed scheme is able to ensure that all closed-loop signals are globally uniformly bounded and the tracking error converges to a residual set exponentially. Simulation results illustrate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a novel event-triggered adaptive fault-tolerant control scheme is proposed for a class of nonlinear systems with unknown actuator faults. Multiplicative faults and additive faults are taken into account simultaneously, both of which may vary with time. Different from existing results, our controller fuses static reliability information and dynamic online information, which is helpful to enhance the fault-tolerant capability. With the aid of an event-triggering mechanism, an actuator switching strategy and a bound estimation approach, the communication burden is significantly reduced and the impacts of the actuator faults as well as the network-induced error are effectively compensated for. Moreover, by employing the prescribed performance control technique, the system tracking error can converge to a predefined arbitrarily small residual set with prescribed convergence rate and maximum overshoot, which implies that the proposed scheme is able to ensure rapid and accurate tracking. Simulation results are presented to illustrate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

In this note, a novel adaptive compensation control scheme is proposed for a class of nonlinear systems with unknown control direction and a possibly infinite number of unknown actuator failures. By introducing a bound estimation approach, high-order Lyapunov functions and a Nussbaum function with faster growth rate, the obstacle caused by unknown failures and unknown control direction is successfully circumvented and all signals of the closed-loop system are proved to be globally uniformly bounded. Moreover, the proposed scheme is able to steer the tracking error into a predefined small residue set. Simulation results are presented to illustrate the effectiveness of the proposed scheme. [ABSTRACT FROM PUBLISHER]

In this paper, a decentralized adaptive backstepping control scheme is proposed for a class of interconnected nonlinear systems with unknown actuator failures. By introducing a smooth function, some integrable auxiliary signals and a bound estimation approach, the effect of actuator failures is successfully compensated for. The proposed scheme has the following features: (1) the total number of failures is allowed to be infinite; (2) global stability of the overall closed-loop system is achieved without any bound knowledge of uncertainties; (3) all system outputs converge to zero asymptotically regardless of the possibly infinite number of failures and the unknown interactions among subsystems. Simulation results on coupled inverted double pendulums are presented to illustrate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]