Containment control with delays, velocity constraints and position constraints in directed changing networks.

This paper discusses a containment problem of multi-agent networks with inconsistently bounded communication time delays in directed changing topologies, where the velocity and position of each follower are, respectively, confined in a nonconvex set and a convex set during its movement. A projection-based distributed control protocol is developed to drive all followers into a target convex area spanned by some given leaders, and a sufficient condition for achieving the constrained containment is established. It is proven that the constrained containment problem can be solved by the developed control protocol only if every follower can communicate with no less than one stationary leader directly or indirectly in the union of the communication topologies. Eventually, a representative simulation experiment is performed to verify the main results.

Decentralized coordinated optimal guaranteed cost control for a roll-to-roll web machine.

This article investigates a coordinated optimal guaranteed cost control (DCOGCC) for a multi-motor roll-to-roll web machine with time-varying and uncertain parameters. The state-space oriented DCOGCC law is designed to ensure that each subsystem of the web machine is stable and the upper bound of performance index is minimum. Linear matrix inequality (LMI) conditions to guarantee the stability of the systems with DCOGCC are derived. A decentralized model is adopted by regarding the entire machine as a synthetic system, then the original decentralized model is transformed into an equivalent one. By choosing appropriate information of consecutive subsystems as coordination variables, the DCOGCC scheme may attenuate the interaction effects between subsystems. The results of some simulations and experiments are given to verify the feasibility and effectiveness of the DCOGCC.

The Influence of Spraying Strategy on the Dynamic Response of Polyurea-Coated Metal Plates to Localized Air Blast Loading: Experimental Investigations.

Polyurea has attracted considerable attention owing to its potential applications in protective fields to improve the resistant performance of structures subjected to damage loads resulting from intentional or accidental explosions. However, different spraying strategies of polyurea may lead to significant differences in overall resistance performance of polyurea-coated structures, and the underlying mechanisms have not been clear until now. This study aims to elucidate the influence of spraying strategy, i.e., spraying area, spraying thickness, and spraying interface condition, on the dynamic response of polyurea-coated steel plates under localized air blast loading. Three types of plates manufactured using different spraying strategies were adopted to evaluate their blast-resistant performance. The spraying strategies used were (i) whole-area spraying, (ii) partial-area spraying, and (iii) in-contact backing of polyurea on the rear surfaces of steel plates. In addition, the influence of spraying thickness of polyurea for whole-area sprayed plates was evaluated. The energy absorbing mechanisms of polyurea backing layers were highlighted. The energy absorption of plates was quantitatively analyzed. The results show that the air blast resistances of whole-area sprayed and in-contact backed plates are both superior to, whereas that of partial-area sprayed plates is inferior to, bare steel counterparts. A suitable spraying thickness of polyurea can significantly reduce the damage of the front steel layer, whereas excessive spraying thickness decreases the overall air blast resistance of plates. The polyurea backing layer exhibits favorable performance in absorbing energy under a whole-area spraying condition. This study provides useful guidance for the design of polyurea-coated metal plates in engineering applications.

Decentralized coordinated control of elastic web winding systems without tension sensor.

In elastic web winding systems, precise regulation of web tension in each span is critical to ensure final product quality, and to achieve low cost by reducing the occurrence of web break or fold. Generally, web winding systems use load cells or swing rolls as tension sensors, which add cost, reduce system reliability and increase the difficulty of control. In this paper, a decentralized coordinated control scheme with tension observers is designed for a three-motor web-winding system. First, two tension observers are proposed to estimate the unwinding and winding tension. The designed observers consider the essential dynamic, radius, and inertial variation effects and only require the modest computational effort. Then, using the estimated tensions as feedback signals, a robust decentralized coordinated controller is adopted to reduce the interaction between subsystems. Asymptotic stabilities of the observer error dynamics and the closed-loop winding systems are demonstrated via Lyapunov stability theory. The observer gains and the controller gains can be obtained by solving matrix inequalities. Finally, some simulations and experiments are performed on a paper winding setup to test the performance of the designed observers and the observer-base DCC method, respectively.