43,554 research outputs found

    Finite time command filtered adaptive fuzzy control for a twin roll inclined casting system

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    This paper, the adaptive fuzzy control problem for finite-time command filtering is studied at the twin roll inclined casting system. An explosion of complexity caused by a differential surge can be avoided by constructing adaptive fuzzy controller combined with command filtering and backstepping schemes. The designed adaptive fuzzy controller ensures simultaneously the stability and tracking performance of the closed-loop system in a limited time, and the tracking error converges in a small neighborhood of the origin. Eventually, a simulation example is given to verify the effectiveness of the proposed scheme

    Finite time command filtered adaptive fuzzy control for a twin roll inclined casting system

    Get PDF
    This paper, the adaptive fuzzy control problem for finite-time command filtering is studied at the twin roll inclined casting system. An explosion of complexity caused by a differential surge can be avoided by constructing adaptive fuzzy controller combined with command filtering and backstepping schemes. The designed adaptive fuzzy controller ensures simultaneously the stability and tracking performance of the closed-loop system in a limited time, and the tracking error converges in a small neighborhood of the origin. Eventually, a simulation example is given to verify the effectiveness of the proposed scheme

    Adaptive neural command filtered fault-tolerant control for a twin roll inclined casting system

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    The essay studies the adaptive neural network fault tolerant control problem based on command filtering, which is aimed at twin-roll inclined casting system (TRICS). A command filter adaptive neural fault-tolerant control scheme for compensating actuator faults is come forward, and meanwhile, the compensating signal is designed to the error of the compensation filter due to the effect of virtual control. Furthermore,the application of Lyapunov stability theory have proved that all the signals in the closed loop system possessed the property of being bounded and stable. Finally, the effectiveness of the control scheme can be verified by means of simulation example

    Adaptive neural command filtered fault-tolerant control for a twin roll inclined casting system

    Get PDF
    The essay studies the adaptive neural network fault tolerant control problem based on command filtering, which is aimed at twin-roll inclined casting system (TRICS). A command filter adaptive neural fault-tolerant control scheme for compensating actuator faults is come forward, and meanwhile, the compensating signal is designed to the error of the compensation filter due to the effect of virtual control. Furthermore,the application of Lyapunov stability theory have proved that all the signals in the closed loop system possessed the property of being bounded and stable. Finally, the effectiveness of the control scheme can be verified by means of simulation example

    Markov-parameter-based adaptive control of 3-axis angular velocity in a six-degree-of-freedom Stewart platform

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    Abstract-Stewart platforms are complex mechanical devices used throughout industry for vibration testing and precision pointing applications. These platforms are nonlinear, strongly coupled MIMO systems. For a six-degree-of-freedom Stewart platform, we consider the problem of three-degree-of-freedom angular-velocity command following. Static nonlinearity inherent in the platform is analyzed, and a closed-loop setup for adaptive command-following control is described. A review of the Markov-parameter-based adaptive control algorithm is given, along with the OKID system identification algorithm, test procedures, and experimental results

    Command Filter Backstepping Sliding Model Control for Lower-Limb Exoskeleton

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    A command filter adaptive fuzzy backstepping control strategy is proposed for lower-limb assisting exoskeleton. Firstly, the human-robot model is established by taking the human body as a passive part, and a coupling torque is introduced to describe the interaction between the exoskeleton and human leg. Then, Vicon motion capture system is employed to obtain the reference trajectory. For the purpose of obviating the “explosion of complexity” in conventional backstepping, a second-order command filter is introduced into the sliding mode control strategy. The fuzzy logic systems (FLSs) are also applied to handle with the chattering problem by estimating the uncertainties and disturbances. Furthermore, the stability of the closed-loop system is proved based on the Lyapunov theory. Finally, simulation results are presented to illustrate the effectiveness of the control strategy

    Stability Assessment and Tuning of an Adaptively Augmented Classical Controller for Launch Vehicle Flight Control

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    Recently, a robust and practical adaptive control scheme for launch vehicles [ [1] has been introduced. It augments a classical controller with a real-time loop-gain adaptation, and it is therefore called Adaptive Augmentation Control (AAC). The loop-gain will be increased from the nominal design when the tracking error between the (filtered) output and the (filtered) command trajectory is large; whereas it will be decreased when excitation of flex or sloshing modes are detected. There is a need to determine the range and rate of the loop-gain adaptation in order to retain (exponential) stability, which is critical in vehicle operation, and to develop some theoretically based heuristic tuning methods for the adaptive law gain parameters. The classical launch vehicle flight controller design technics are based on gain-scheduling, whereby the launch vehicle dynamics model is linearized at selected operating points along the nominal tracking command trajectory, and Linear Time-Invariant (LTI) controller design techniques are employed to ensure asymptotic stability of the tracking error dynamics, typically by meeting some prescribed Gain Margin (GM) and Phase Margin (PM) specifications. The controller gains at the design points are then scheduled, tuned and sometimes interpolated to achieve good performance and stability robustness under external disturbances (e.g. winds) and structural perturbations (e.g. vehicle modeling errors). While the GM does give a bound for loop-gain variation without losing stability, it is for constant dispersions of the loop-gain because the GM is based on frequency-domain analysis, which is applicable only for LTI systems. The real-time adaptive loop-gain variation of the AAC effectively renders the closed-loop system a time-varying system, for which it is well-known that the LTI system stability criterion is neither necessary nor sufficient when applying to a Linear Time-Varying (LTV) system in a frozen-time fashion. Therefore, a generalized stability metric for time-varying loop=gain perturbations is needed for the AAC
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