No abstract

This paper is concerned with the active fault tolerant control (FTC) problem for an Internet-based networked threetank system (INTTS) serving as a benchmark system for evaluating networked FTC algorithms. The INTTS has two parts located at Tsinghua University in China and at the University of South Wales in the UK, respectively, which are connected via Internet. With the INTTS as an experimental platform, the active FTC problem is investigated for a class of nonlinear networked systems subject to partial actuator failures. A binary switching random sequence with a known distribution is employed to describe the packet dropout phenomena induced by network cables with limited-capacity.Once a specific actuator failure is detected and confirmed by a fault diagnosis unit, the control law is then reconfigured based on the information of the detected fault. Both the stability and the H ∞ disturbance attenuation performance are guaranteed for the closed-loop system by using the remaining reliable actuators. Extensive experiments are carried out on the active fault tolerant control problem of the INTTS with partial actuator failures and the effectiveness of the proposed scheme is illustrated. KeywordsActive fault tolerant control, Internet-based networked three-tank system, actuator failure, controller reconfiguration, random packet dropout.

We propose a scheme that can generate tunable optomechanical induced transparency (OMIT) in a hybrid piezo-optomechanical cavity system. The system is constituted of a high quality planar distributed Bragg reflectors (DBR) cavity, which the quality is improved by an embedded submicrometer three-dimensional Gaussian-shaped defect. Moreover, the interdigitated transducers (IDTs) are fabricated on the surface of the cavity to generate the surface acoustic waves (SAW). Here, the DBR cavity structure modified with the embedded Gaussian-shaped defect is proposed by F.Ding et al., relative to the traditional DBR structures with the same number of mirror pairs, the quality factor of this design can be effectively improved by nearly two orders, which can exceed 10 5 [1]. We show that when a strong pump optical field and a weak probe optical field are applied to the hybrid cavity system simultaneously, at the presence of the SAW, a transmission window can be obtained in the weak output probe field. This phenomenon arises because that under the actuation of the SAW, the upper Bragg mirrors is vibrated as a bulk acoustic resonator(BAR). Then the two-level system formed by the energy levels of the DBR cavity is turned into a standard three-level optomechanical cavity system, which is formed by the energy levels of the DBR cavity and the BAR. Under the quantum interference between different energy-level pathways, the optomechanically induced transparency (OMIT) occurs, as a result, the transmission window is observed in the weak output probe field. Inversely, without the actuation of the SAW, the transmission window disappears. Our scheme can be applied in the fields of optical switches and quantum information processing in solid-state quantum systems.