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MATHEMATICAL PROBLEMS IN ENGINEERING 2014年第1期2014卷 1-12页

作者： Yu, Hongchuan Zhang, Jian J. Jiao, Zheng Bournemouth Univ Natl Ctr Comp Animat Poole BH12 5BB Dorset England Shanghai Univ Sch Environm & Chem Engn Shanghai 200041 Peoples R China

We present a novel framework to compute geodesics on implicit surfaces and point clouds. Our framework consists of three parts, particle based approximate geodesics on implicit surfaces, Cartesian grid based approximate geodesics on point clouds, and geodesic correction. The first two parts can effectively generate approximate geodesics on implicit surfaces and point clouds, respectively. By introducing the geodesic curvature flow, the third part produces smooth and accurate geodesic solutions. Differing from most of the existing methods, our algorithms can converge to a given tolerance. The presented computational framework is suitable for arbitrary implicit hypersurfaces or point clouds with high genus or high curvature.

关键词： GEODESICS (Mathematics) APPROXIMATION theory STOCHASTIC convergence computer algorithms HYPERSURFACES MATHEMATICAL analysis

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Testbed Validation of Location-Scheduled Control of a Reconfigurable Flux-Pinned Spacecraft Formation

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JOURNAL OF SPACECRAFT AND ROCKETS 2013年第6期50卷 1235-1247页

作者： Sorgenfrei, Matthew C. Jones, Laura L. Joshi, Sanjay S. Peck, Mason A. Univ Calif Davis Dept Mech & Aerosp Engn Davis CA 95616 USA Cornell Univ Dept Mech & Aerosp Engn Ithaca NY 14850 USA

Unique mission architectures become possible when formations of close-proximity spacecraft have the ability to reconfigure on orbit to adapt to different mission requirements. A necessary precursor to the realization of these missions, however, is the development of control architectures that accommodate the different geometries of a reconfigurable space system at different mission phases. This paper investigates the closed-loop control of a reconfigurable set of two CubeSat-scale spacecraft that are connected via noncontacting flux-pinned interfaces. A design concept known as location-scheduled control is used both to tune a Proportional-Integral-Derivative control law and to choose an optimal configuration for the spacecraft formation during a rest-to-rest reorientation maneuver. The location-scheduled control approach makes use of a genetic algorithm to search the design space of configurations and controller gains. The simulated performance of the controller is compared to experiments performed on Cornell University's Float Cube testbed, a planar air-bearing environment for validating nanosatellite-scale spacecraft architectures. The system's performance using the location-scheduled control-derived gains shows the same trends in the simulated and experimental data while providing insight into the behavior of the flux-pinned interfaces. Both simulation and experimental results also suggest that the location-scheduled control algorithm can select a combination of controller gains and system configuration that outperforms a human engineer's informed trial-and-error search.

关键词： System performance optimal configuration mission architecture Geologic Formations aerospace systems design concept configurability Spacecraft Controllers simulating Religious Missions computer algorithms

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Constrained adaptive tracking and command shaped vibration control of flexible hypersonic vehicles

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IET CONTROL THEORY AND APPLICATIONS 2015年第12期9卷 1857-1868页

作者： Su, Xiaofeng Jia, Yingmin Beihang Univ BUAA Div Res 7 Beijing 100191 Peoples R China Beihang Univ BUAA Dept Syst & Control Beijing 100191 Peoples R China

This study presents a new approach, which integrates the input shaping technique and the constrained adaptive backstepping control method, for constrained adaptive tracking and elastic vibration control of flexible hypersonic vehicles. Specifically, the input shaper as a feedforward part is implemented outside the feedback loop, which can achieve vibration suppression for flexible dynamics;whereas for the feedback loop, the vehicle model is decomposed into functional subsystems, and the decentralised approach is used. Then, by introducing the command filter and the auxiliary system, constrained adaptive control law is formulated to make the closed-loop system follow the shaped reference trajectory and attenuate the elastic vibration in the presence of parameter uncertainties, external disturbances and input saturation constraints. An attractive feature of this proposed control algorithm is that all signals of closed-loop system are uniformly ultimately bounded and the tracking error converges to a residual set which can be made sufficiently small by properly designing control parameters. Moreover, by applying the shaped commands, flexible dynamics with less elastic deformation and vibration can be achieved without destroying the closed-loop performance. Simulation results are provided to verify the effectiveness of the proposed control method.

关键词： Feedback loop parameter uncertainty vibration control Vehicle model control law Closed loop systems Control Methods hypersonic vehicles computer algorithms FLEXIBLE vibration suppression Adaptive tracking AUXILIARY SYSTEMS elastic vibration commands

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Rotor losses in fault-tolerant permanent magnet synchronous machines

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IET ELECTRIC POWER APPLICATIONS 2011年第1期5卷 75-88页

作者： Raminosoa, T. Gerada, C. Othman, N. Lillo, L. D. Univ Nottingham Dept Elect & Elect Engn Nottingham NG7 2RD England

The necessary reliability of safety-critical aerospace drive systems is often partly achieved by using fault-tolerant (FT) electrical machines. There are numerous published literatures on the design of FT machines as well as on control algorithms used to maintain drive operation with an incurred fault. This study is set to look at the rotor losses in three-and five-phase surface mount permanent magnet machines when operating in faulty mode in order to highlight the influence of the post-fault control strategy and winding configuration. Although the work presented in this study is mainly focused on FT control methodologies targeted at mitigating phase open circuit faults, the implications of short-circuit faults is also considered and discussed.

关键词： Fault tolerance rotor losses Circuit faults computer algorithms Short circuits Permanent magnet synchronous machines

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Real-Time Hardware-in-the-Loop Laboratory Testing for Multisensor Sense and Avoid Systems

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INTERNATIONAL JOURNAL OF AEROSPACE ENGINEERING 2013年第1期2013卷 9.1-9.9页

作者： Fasano, Giancarmine Accardo, Domenico Forlenza, Lidia Renga, Alfredo Rufino, Giancarlo Tancredi, Urbano Moccia, Antonio Univ Naples Federico II Dept Ind Engn DII I-80125 Naples Italy Univ Naples Parthenope Ctr Direz Dept Technol I-80143 Naples Italy

This paper focuses on a hardware-in-the-loop facility aimed at real-time testing of architectures and algorithms of multisensor sense and avoid systems. It was developed within a research project aimed at flight demonstration of autonomous non-cooperative collision avoidance for Unmanned Aircraft Systems. In this framework, an optionally piloted Very Light Aircraft was used as experimental platform. The flight system is based on multiple-sensor data integration and it includes a Ka-band radar, four electro-optical sensors, and two dedicated processing units. The laboratory test system was developed with the primary aim of prototype validation before multi-sensor tracking and collision avoidance flight tests. System concept, hardware/software components, and operating modes are described in the paper. The facility has been built with a modular approach including both flight hardware and simulated systems and can work on the basis of experimentally tested or synthetically generated scenarios. Indeed, hybrid operating modes are also foreseen which enable performance assessment also in the case of alternative sensing architectures and flight scenarios that are hardly reproducible during flight tests. Real-time multisensor tracking results based on flight data are reported, which demonstrate reliability of the laboratory simulation while also showing the effectiveness of radar/electro-optical fusion in a non-cooperative collision avoidance architecture.

关键词： REAL-time computing HARDWARE-in-the-loop simulation SENSOR networks computer architecture computer algorithms COLLISIONS (Nuclear physics) DRONE aircraft ELECTROOPTICAL devices

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Robust wavelet-neural-network sliding-mode control system for permanent magnet synchronous motor drive

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IET ELECTRIC POWER APPLICATIONS 2011年第1期5卷 113-132页

作者： El-Sousy, F. F. M. King Saud Univ Dept Elect Engn Coll Engn Al Kharj Riyadh 11451 Saudi Arabia

An intelligent sliding-mode speed controller for achieving favourable decoupling control and highprecision speed tracking performance of permanent-magnet synchronous motor (PMSM) drives is proposed. The intelligent controller consists of a sliding-mode controller (SMC) in the feedback loop in addition to an online trained wavelet-neural-network controller (WNNC) connected in parallel with the SMC to construct a robust wavelet-neural-network sliding-mode controller (RWNNSMC). The RWNNSMC controller combines the merits of the SMC with robust characteristics and the WNNC which combines the capability of artificial neural networks for online learning ability and the capability of wavelet decomposition for identification ability. The theoretical analyses of both SMC and WNNC speed controllers are developed. The WNN bound observer is utilised to predict the uncertain system dynamics to relax the requirement of uncertainty bound in the design of SMC. A computer simulation is developed to demonstrate the effectiveness of the proposed intelligent sliding-mode speed controller. An experimental system is established to verify the effectiveness of the proposed control system. All control algorithms are implemented in a TMS320C31 digital signal processor-based control computer. The simulated and experimental results confirm that the proposed RWNNSMC grants robust performance and precise response regardless of load disturbances and PMSM parameter uncertainties.

关键词： PERMANENT magnets SLIDING mode control ROBUST control NEURAL networks (computer science) computer simulation computer algorithms

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Active fault-tolerant control of dissimilar redundant actuation system based on performance degradation reference models

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JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS 2017年第2期354卷 1087-1108页

作者： Shi, Cun Wang, Shaoping Wang, Xingjian Wang, Jun Tomovic, Mileta M. Beihang Univ Sch Automat Sci & Elect Engn Beijing 100191 Peoples R China Old Dominion Univ Coll Engn & Technol Norfolk VA 23529 USA

Dissimilar redundant actuation system (DRAS) composed of one hydraulic actuator (HA) and one electrohydrostatic actuator (EHA) represents industry trend in actuation system towards more electric aircraft (MEA). The paper investigates performance degradation of DRAS under the system malfunctions and addresses the problem of active switching of DRAS from HA to EHA to ensure the reliable actuation and efficient control. A novel active fault-tolerant controller (AFTC) based on the performance degradation reference models (PDRM) is presented. The main performance degradation rules of DRAS are determined based on the effect of fault degree on the system root locus and the proposed PDRM are then constructed as a series of second-order functions. Finally, an intelligent matching algorithm (MA) is developed based on the dominant closed-loop poles, and a set of adaptive fuzzy controllers (AFC) are designed based on the proposed PDRM and the intelligent MA to achieve the performance degraded fault-tolerant capability. Extensive simulation results are presented to indicate the effectiveness of the proposed AFTC control scheme. (C) 2016 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.

关键词： FAULT tolerance (Engineering) HYDRAULIC engineering HYDROSTATICS HYBRID electric airplanes ACTUATOR design & construction computer algorithms DESIGN & construction

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MPC Constraint Analysis-Bayesian Approach via a Continuous-Valued Profit Function

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2009年第8期48卷 3944-3954页

作者： Akande, Seyi Huang, Biao Lee, Kwan Ho Univ Alberta Dept Chem & Mat Engn Edmonton AB T6G 2G6 Canada

Model predictive control (MPC) is one of the most studied modem control technologies. Among the various subjects investigated, controller performance assessment of MPC has received considerable attention in recent time. Various approaches and algorithms have been proposed for the assessment of MPCs. In this work, we propose a novel approach to MPC constraint analysis by considering the economic objective function as a continuous-valued function within a Bayesian probabilistic framework. The analysis involves inference of the effect of a decision to adjust the limits of the constrained variables with regards to the achievable profits (decision evaluation) as well as inference of constraint limits that should be adjusted so as to achieve a specified profit value (decision making). The benefits of this approach include a more generalized definition of quality variables, the development of a more rigorous formulation of the problem to address linear and quadratic objective functions and thereby obtaining closed form solutions, and maximum-likelihood location determination of the quality variables in the decision making process. The approach is illustrated with the use of simulations and a pilot-scale experiment.

关键词： PREDICTIVE control PREDICTION models BAYESIAN analysis DECISION theory CONTROL theory (Mathematics) computer algorithms MAXIMUM likelihood statistics PROBLEM solving CONTINUOUS functions

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A two-phase GI/PH/1 → •/PH/1/0 system with losses

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AUTOMATION AND REMOTE CONTROL 2011年第5期72卷 1004-1016页

作者： Klimenok, V. I. Taramin, O. S. Belarusian State Univ Minsk 220050 BELARUS

We find a stationary distribution and productivity characteristics for a two-phase queueing system with recurrent input flow. The servicing units are single-line on both phases. The servicing times have phase-type distributions. On the first phase, there is an infinite buffer. There is no intermediate buffer. In case the second phase device is busy at the time a claim has finished going through the first phase, this claim leaves the system unserved (is lost).

关键词： QUEUEING networks (Data transmission) MARKOV processes WEIBULL distribution ARBITRARY constants MATRICES POISSON algebras computer algorithms

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Wireless interference power estimation for inter-cell interference coordination

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IET COMMUNICATIONS 2015年第12期9卷 1539-1546页

作者： Wigren, Torbjorn Ericsson AB WMR TA SE-16480 Stockholm Sweden

To enable uplink inter-cell interference coordination in cellular networks, estimates of the powers generated by the own serving cell, the neighbour cells and the thermal noise processes need to be made available. An algorithm for such high-bandwidth interference power splitting is derived in the study. The algorithm does not require inter-base station communication. The resulting estimates support self-organising network interference management and coordinated scheduling, both technologies being important in new heterogeneous networks. A new method for G-matrix tracking is also outlined, based on the estimates obtained from the proposed algorithm. The performance evaluation, performed for a 3G wideband code division multiple access setup of the algorithm, shows that the estimation inaccuracy's of the proposed algorithm is below 10-15% in the relevant operating region.

关键词： WIRELESS communication systems INTERFERENCE channels (Telecommunications) computer algorithms BROADBAND communication systems CODE division multiple access 3G (Telecommunication)

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