查看更多>>摘要：In this article, a predefined-time event-triggered attitude consensus control problem is investigated for multiple spacecraft with time-varying state constraints. A backstepping-based control scheme for achieving a consensus in spacecraft attitudes within a predefined time is presented. To enhance the efficiency of communication resource utilization, an event-triggering mechanism is designed by employing a saturation function. This mechanism allows for the application of three existing triggering strategies in multiple spacecraft systems. Then, a novel asymmetric fractional barrier Lyapunov function (BLF) guarantees adherence to time-varying constraints while addressing the issue of excessive control amplitude associated with large constraint boundaries in conventional logarithmic BLFs (LBLFs). This enables the proposed approach to handle both constrained and unconstrained scenarios. The efficacy of the proposed control strategy is illustrated through numerical simulation examples.
查看更多>>摘要：It remains a challenge to improve the accuracy of impedance rendering while ensuring stability under strong impacts during human-robot interaction. In this work, we aim to render the desired impedance for the flexible joint under an admittance control scheme with prescribed performance function (PPF). Specially, Gaussian kernels are introduced as the slack terms for PPF, so that the control stability can be maintained in the presence of abrupt external torques. Meanwhile, a narrower error envelope is yielded when such torques are absent, which also improves the fidelity of the desired impedance model. To achieve the prescribed tracking performance of the inner position loop, a two-stage backstepping control is proposed by defining two first-order composite error surfaces bridged by a second-order dynamic surface. This promulgates the minimum number of backstepping stages under the available state feedback, thus avoiding “explosion of terms.” In addition, dual-adaptive neural networks are incorporated into the backstepping control to compensate for the matched and unmatched disturbances. Real-time experiments are conducted to validate the appeal of the proposed method.
查看更多>>摘要：The work addresses the issue of observer-based control for networked nonlinear systems suffering from denial-of-service (DoS) attacks which are modeled in a novel persistent dwell time (PDT) switched form. The interval type-2 Takagi-Sugeno fuzzy model is adopted to accurately characterize the nonlinear feature in investigated systems and effectively capture uncertain parameters via membership functions. It should be noticed that a new framework comprising a special PDT switching strategy is proposed for distributed DoS attacks with energy limitation. Accordingly, the controlled system is converted into a complex and constrained PDT-switched system. Subsequently, based on weak multi-Lyapunov functions, membership-function-dependent sufficient criteria are offered for judging the globally uniformly exponential stability of the researched closed-loop system, from which the gains of the observer and the controller can be computed. Finally, an algorithm generating PDT switching sequences for distributed DoS attacks is proposed, and simulations are given to substantiate the usability of the developed approach.
查看更多>>摘要：This article investigates the $H_{\infty } $ optimal output-feedback control problem of heterogeneous multiagent systems. First, a hierarchical control scheme is designed to reduce the algorithm’s complexity and the expected global performance constraints can be ensured by designing compensation input indicator. Second, a relaxation parameter is introduced to derive the optimal solution under output feedback. Additionally, a policy iteration algorithm and vectorization method are presented to determine local and collaborative control gains. This relaxation parameter serves to ease the design conditions for performance indicator. In addition, adaptive dynamic programming (ADP) is introduced and reversible datasets are designed to obtain optimal parameters with unknown drift dynamics. This design achieves model-free control of optimal output feedback for heterogeneous multiagent systems. Finally, the effectiveness of the control schemes is validated using F-16 aircraft and 4-wheel autonomous vehicles as examples.
查看更多>>摘要：In this article, the problem of piecewise fault detection (FD) for continuous-time piecewise linear (PWL) system with measurement outliers via new event-triggered (ET) mechanisms is investigated. First, piecewise FD observer with adaptive saturation of output errors is designed to mitigate the effect of outliers on the residual signals, such that false alarms are avoided through the established FD scheme. Then, based on the presented piecewise FD observer, a new ET design scheme that depends on the different regions where the states of the PWL system and piecewise FD observer are located is proposed, and an ET FD method is studied through the ET mechanisms. Unlike the existing results, the established FD scheme can effectively avoid false alarm caused by outliers, and the piecewise FD observer is designed separately from the new ET mechanisms, while co-design is necessary in the existing results. Finally, the effectiveness of the presented scheme is demonstrated by simulation examples.
查看更多>>摘要：This article proposes a novel data-driven approach for studying the stabilization of continuous-time delayed systems (CDSs) with both unknown model parameters and denial-of-service (DoS) attacks. Due to the effects of DoS attacks, such controlled CDSs can be viewed as a switched system with two modes: a stable mode during dormant intervals and an unstable one during attack intervals. Because of the switching character of the CDS with DoS attacks, some well-known data-driven control methods can not be used directly. To tackle this issue, a new relationship between the dormancy and activation periods of DoS attacks is built, which offers a more reasonable description of DoS attacks. Additionally, in the presence of measurement noise, a novel lemma (Lemma 3) is introduced to establish a data-based representation of CDSs using noisy measurement data. Without the need of explicit system parameter identification, stabilization criteria and control gain matrix are derived solely based on the input-state data. Finally, the effectiveness and good performance of the proposed method are illustrated through a numerical example and a power system.
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