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This article considers the design problem of H∞$$ {H}_{\infty } $$ observer‐based fault‐tolerant control under three faulty cases: sensor only, actuator only, and both sensor and actuator faults. To save communication resources, the event trigger mechanism method is used for sensor‐to‐observer and observer‐to‐controller transmissions. In this case, the design method of the new H∞$$ {H}_{\infty } $$ observer is given for obtaining estimating both states and faults which are used to design observer‐based H∞$$ {H}_{\infty } $$ fault‐tolerant controllers. In particular, the virtual observer is designed to suppress the effects of faults on the system. As the virtual observer contains unmeasurable system information, the real observer is built on top of the virtual observer to eliminate the unmeasurable information. Finally, the feasibility of the approach is tested with a numerical example. [ABSTRACT FROM AUTHOR]

This article studies the simultaneous fault‐tolerant control and disturbance rejection for systems with fault in polynomial form. The unknown external disturbance is considered to be caused by the external source system, and the fault can be expressed as a polynomial function of time. Combining the fault observer and the disturbance observer, a controller is designed, which can not only diagnose the fault, but also improve the anti‐disturbance performance. Finally, a numerical example is given to verify the validity of the results. [ABSTRACT FROM AUTHOR]

Summary: A cart‐pendulum system is a nonlinear underactuated mechanical system with two degrees of freedom. This paper addresses the motion trajectory design and tracking control problems for this underactuated system. First, a friction‐like control law is designed for the system. Then, the characteristics of the closed‐loop control system are analyzed. Second, a new method of constructing an optimal trajectory for the system is developed. Then, a tracking control law is designed to quickly track the constructed trajectory. It guarantees that the motion control of the cart‐pendulum system is achieved along a reference trajectory. Finally, a numerical example is presented to demonstrate the effectiveness of the theoretical results. This study constructs an optimal trajectory for the cart‐pendulum system in its whole motion space and solves the motion control objective by tracking the constructed trajectory. It has many advantages compared with other motion control methods, eg, the optimal motion control objective of the system is achieved by a single control law; and the motion process and transient characteristics (eg, the settling time) of the control system can be accurately predicted. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we investigate the pinning synchronization of directed complex network with time‐varying delay under the adaptive aperiodically intermittent control. First, the model of a directed complex network is established, the interaction graph of which is not required to contain a directed spanning tree, and for which an adaptive aperiodically intermittent feedback controller is well designed. In addition, based on the Lyapunov function method and linear matrix inequality technique, several asymptotical synchronization criteria are derived via an aperiodically intermittent strategy, which is superior to the periodical scheme. Moreover, the adaptive strategy providing the exponential convergence rate and the pinning algorithm demonstrating how to select pinned nodes are presented. Finally, numerical examples are provided to illustrate the effectiveness of the derived theoretical results. [ABSTRACT FROM AUTHOR]

SUMMARY An underactuated three-link gymnast robot (UTGR) is a simple model of a gymnast on a high bar. The control objective of a UTGR is to swing it up from a point near the straight-down position and to stabilize it at the straight-up position. To achieve this, we first divide the motion space into two subspaces, swing-up area and balancing area, and design a controller for each. The design of a swing-up control law that ensures that the UTGR enters the balancing area is crucial because the UTGR is subject to a nonholonomic constraint and is highly nonlinear during the swing-up motion. This study focused on how to design a swing-up control law that contains no singularities. The key concept is the introduction of a virtual coupling between control torques, which converts the problem of avoiding singularities to one of imposing constraints on the parameters of the control law and properly selecting those parameters. A swing-up control law thus designed ensures that the UTGR enters the balancing area in a natural stretched-out posture. This makes it easy to stabilize the UTGR in the balancing area. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]