Summary
This article focuses on the consensus problem of leader‐following fractional‐order multi‐agent systems (MASs) with general linear and Lipschitz nonlinear dynamics. First, the distributed adaptive protocols for linear and nonlinear fractional‐order MASs are constructed, respectively. We allow the control coupling gains to be time varying for each agent. Moreover, the adaptive modification schemes for the control gain are designed, which renders smaller control gains and thus requires smaller amplitude on the control input without sacrificing consensus convergence. Second, based on fractional‐order Lyapunov stability theorem and Barbalat's lemma, two novel sufficient conditions in terms of linear matrix inequalities are provided to ensure that the leader‐following consensus can be obtained in the case for any undirected connected communication graph. Furthermore, we show that the proposed algorithm also works for consensus of agents with intrinsic Lipschitz nonlinear dynamics. As a result, the proposed framework requires no global information and thus can be implemented in a fully distributed manner. Finally, the numerical simulations are given to demonstrate the effectiveness of obtained the theoretical results.
Printing of versatile chemical and biological inks for protein and cell patterning was achieved using a simple and cost-effective flash foam stamp (FFS). The grey-scale mask fabricated stamp can generate multiple protein gradients with one-post stamping. Due to the importance of spatially controlled protein patterns in both biology and tissue engineering, this straightforward and reliable tool is an accessible solution for resource-limited laboratories conducting molecular patterning experiments.
In this article, an adaptive nonsingular terminal sliding mode control scheme based on fractional order is proposed for a cable-driven manipulator with external disturbances, where the concentration is uncertain and the upper limit is known or unknown. Furthermore, a new adaptive fractional-order nonsingular fast terminal sliding mode algorithm with time-delay estimation is developed. The delay estimation unit can be used to properly compensate the centralized unknown dynamics of the system, thereby obtaining attractive model-free characteristics. A characteristic of the control scheme in this article is that by using the adaptive tuning law, the upper limit of the uncertainty is estimated only by the speed and position measurement so as to achieve the effects of rapid convergence, high accuracy, and vibration reduction. In addition, the proposed controller effectively eliminates the effects of jitter without losing robustness and accuracy. The simulation results show the effectiveness of the proposed control scheme.
The mechanical interface has the characteristics of low shock and vibration, and is emphasized in the aerospace and ocean engineering fields. In this paper, a mechanical interface
based on coupled cylindrical cam mechanisms is designed. It can achieve the expected functions, but there exist faults in some times. The fault modes and causes of the interface are
firstly analyzed. Then a design approach based on Monte Carlo simulation is presented for
analyzing and optimizing its reliability. According to the fault modes, the performance functions of the interface are established for obtaining the optimal scheme. A case is given to
illustrate the proposed method. The simulation results and the prototype experiments prove
that the optimization scheme effectively improves the reliability of the interface, and has
better performance than the original one.
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