Robust Fault-Tolerant Tracking Control for Nonlinear Networked Control System: Asynchronous Switched Polytopic Approach

This paper is concerned with the robust fault-tolerant tracking control problem for networked control system (NCS). Firstly, considering the locally overlapped switching law widely existed in engineering applications, the NCS is modeled as a locally overlapped switched polytopic system to reduce designing conservatism and solving complexity. Then, switched parameter dependent fault-tolerant tracking controllers are constructed to deal with the asynchronous switching phenomenon caused by the updating delays of the switching signals and weighted coefficients. Additionally, the global uniform asymptotic stability in the mean (GUAS-M) and desired weighted l2 performance are guaranteed by combining the switched parameter dependent Lyapunov functional method with the average dwell time (ADT) method, and the feasible conditions for the fault-tolerant tracking controllers are obtained in the form of linear matrix inequalities (LMIs). Finally, the performance of the proposed approach is verified on a highly maneuverable technology (HiMAT) vehicle’s tracking control problem. Simulation results show the effectiveness of the proposed method

Discrete Time Systems

Discrete-Time Systems comprehend an important and broad research field. The consolidation of digital-based computational means in the present, pushes a technological tool into the field with a tremendous impact in areas like Control, Signal Processing, Communications, System Modelling and related Applications. This book attempts to give a scope in the wide area of Discrete-Time Systems. Their contents are grouped conveniently in sections according to significant areas, namely Filtering, Fixed and Adaptive Control Systems, Stability Problems and Miscellaneous Applications. We think that the contribution of the book enlarges the field of the Discrete-Time Systems with signification in the present state-of-the-art. Despite the vertiginous advance in the field, we also believe that the topics described here allow us also to look through some main tendencies in the next years in the research area

Mid-infrared dual comb spectroscopy with asynchronous optical parametric oscillators

Dual-comb spectroscopy (DCS) is a novel approach that uses asynchronous broadband coherent sources to achieve Fourier-transform-like spectroscopy but with no moving parts and at kHz acquisition rates. To date, fully resolved and accurate dual-comb spectrometers have been demonstrated in the near-infrared and applied to broadband spectroscopy for precise measurement of molecular centerlines, spectral lidar, and greenhouse gases from the near- to mid-IR. This thesis describes DCS with asynchronous optical parametric oscillators and explores their applications in rapid, high-resolution broadband spectroscopy in the mid-infared. Initially a dual-comb spectrometer was designed with two identical optical parametric oscillators (OPOs) pumped by two identical Yb:fibre lasers and its stability performance was characterized measuring relative intensity noise. First experiments were accomplished by using free-running independent MgO:PPLN based OPOs with a repetition-rate difference of 500 Hz, achieving resolutions of 0.2 cm-1 across a wavelength range 3.1 to 3.5 μm; an absolute wavelength calibration technique was employed to allow registration and averaging of consecutively acquired dual-comb spectra. Then experiments were repeated with a dual-comb source for the spectral fingerprint region based on a pair of entirely free-running OPOs, each pumped by a 1-µm femtosecond laser and utilizing the new gain medium orientation-patterned gallium phosphide (OPGaP) to produce broadband idler pulses tunable from 6–8 µm. Methane absorption spectroscopy in the deep infrared region was demonstrated with the same wavelength calibration approach for both dual-comb spectrometers, leading to a high quality and low-noise absorbance measurement with spectral coverage simultaneously spanning the methane P, Q and R branches in good agreement with the Hitran database

Emulation of Narrowband Powerline Data Transmission Channels and Evaluation of PLC Systems

This work proposes advanced emulation of the physical layer behavior of NB-PLC channels and the application of a channel emulator for the evaluation of NB-PLC systems. In addition, test procedures and reference channels are proposed to improve efficiency and accuracy in the system evaluation and classification. This work shows that the channel emulator-based solution opens new ways toward flexible, reliable and technology-independent performance assessment of PLC modems

Proceedings of the Third International Mobile Satellite Conference (IMSC 1993)

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial cellular communications services. While the first and second International Mobile Satellite Conferences (IMSC) mostly concentrated on technical advances, this Third IMSC also focuses on the increasing worldwide commercial activities in Mobile Satellite Services. Because of the large service areas provided by such systems, it is important to consider political and regulatory issues in addition to technical and user requirements issues. Topics covered include: the direct broadcast of audio programming from satellites; spacecraft technology; regulatory and policy considerations; advanced system concepts and analysis; propagation; and user requirements and applications