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NUMERICALLY RELIABLE SOFTWARE FOR control - THE SLICE LIBRARY

IEE PROCEEDINGS-D control THEORY AND APPLICATIONS 1986年第2期133卷 73-82页

作者： WILLIAMS, TWC School of Computing Kingston Polytechnic Kingston upon Thames UK

The algorithms developed in the control literature have generally been devised from a purely theoretical viewpoint, with no attention being paid to the numerical difficulties which can arise when they are implemented in the finite-precision arithmetic of digital computers. The rounding errors which then result can cause many of these algorithms to produce catastrophically bad results, particularly if the initial data supplied is poorly scaled. The numerical analysis background required to study these problems is given in the paper, and methods available to overcome them described. These are detailed with special reference to the SLICE library of numerically reliable Fortran algorithms for control.

关键词： digital computers numerically reliable FORTRAN algorithms control engineering computing finite-precision arithmetic Digital arithmetic methods digital arithmetic roundoff errors computerised control numerical analysis rounding errors SLICE library

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Performance evaluation of RW-Quadrotor and Bi-Quadrotor for payload delivery

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IET INTELLIGENT TRANSPORT SYSTEMS 2023年第11期17卷 2221-2236页

作者： Dalwadi, Nihal Deb, Dipankar Ozana, Stepan Inst Infrastructure Technol Res & Management Dept Elect Engn Ahmadabad India VSB Tech Univ Ostrava Fac Elect Engn & Comp Sci Dept Cybernet & Biomed Engn Ostrava Czech Republic Inst Infrastructure Technol Res & Management Dept Elect Engn Ahmadabad 380026 India

Payload delivery is one of the many Unmanned Aerial Vehicle (UAV) applications that save time, energy, and human resources. The present simulation study compares rotary-wing quadrotors (RW-Quadrotors) and tail-sitter biplane quadrotors (Bi-Quadrotors) under payload delivery conditions that help to choose the best UAV for the particular mission. A comparative study is performed based on (i) time taken to accomplish the given mission, (ii) trajectory tracking performance, (iii) motor speed throughout the entire flight envelope, and (iv) remains SoC (State of Charge) after the mission. Furthermore, a Backstepping controller (BSC) and an Adaptive Backstepping controller (ABSC) are developed for both UAVs to handle mass changes during flight while Genetic Algorithm (GA) is used for the gain optimization. MATLAB Simulink-based numerical simulation reveals that the Bi-Quadrotor has a lower average rotor speed than the RW-Quadrotor. However, the Bi-Quadrotor's SoC after the mission is higher than the RW-Quadrotor, and it took less time to accomplish the mission. The ABSC designed for RW-Quadrotor and Bi-Quadrotor effectively handles mass change during the mission. However, the BSC controller increases energy consumption for the Bi-Quadrotor in the presence of wind gusts.

关键词： control engineering computing intelligent sensors Internet of Things path planning

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HARMONIC MINIMIZATION IN MICROPROCESSOR controlLED CURRENT FED PWM INVERTER DRIVES

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IEE PROCEEDINGS-B ELECTRIC POWER APPLICATIONS 1987年第1期134卷 25-41页

作者： BOWES, SR BULLOUGH, RI Department of Electrical and Electronic Engineering University of Bristol Bristol UK

New microprocessor-based pulse-width modulation (PWM) control techniques are presented for the current fed inverter (CFI) drive, which minimise the harmonic torque and speed-ripple effects normally associated with low-speed quasi-square-wave operations of CFI drives. It is shown how high-pulse number PWM harmonic elimination current strategies can be developed and used to eliminate substantially greater numbers of harmonics, which hitherto had not been thought a practical possibility. In addition, new PWM harmonic minimisation strategies are presented for the CFI drive, based on the minimisation of a weighted function of stator current harmonic amplitudes. These PWM current minimisation strategies are shown to give superior performance in terms of smoother rotor motion, reduced speed ripple and positional error and can therefore be used to extend the viable range of operation and application of the CFI drive. The complete theoretical development of the new harmonic minimisation PWM current strategies is presented and confirmed using both computed results and experimental results obtained from a previously developed microprocessor-controlled PWM CFI drive. Finally, the PWM control techniques are extended to the ‘duplex’ CFI drive and predicted to give considerable improvements in low-speed performance.

关键词： electric drives minimisation harmonics CFI drive Power convertors and power supplies to apparatus Power engineering computing harmonic torque speed-ripple effects Drives electric current control smoother rotor motion control of electric power systems Current control microprocessor-based pulse-width modulation control invertors current fed PWM inverter drives pulse width modulation harmonic minimisation control engineering computing stator current harmonic amplitudes computerised control

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Auto-tuning scheme for improved current sharing of multiphase DC-DC converters

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IET POWER ELECTRONICS 2012年第9期5卷 1605-1613页

作者： Su, J. -T. Lin, C. -W. Natl Taiwan Univ Dept Elect Engn Taipei 10764 Taiwan

In this study, an auto-tuning scheme is presented to realise simple and accurate calibration, for improved current sharing in multiphase DC-DC converters. The proposed control scheme is based on a look-up table method to automatically tune the pre-stored parameters to obtain the same effect as equal output inductance and direct current resistor (DCR). It ensures that time constant is perfectly matched in a conventional DCR current-sensing technique. The proposed scheme provides a low-cost solution with ease of implementation because it is fully designed using a digital control technique without any external phase compensation elements. The proposed scheme is verified on a two-phase interleaved DC-DC buck converter with a 12-V input and a 1-V, 40-A output. Simulation and experimental results are presented to demonstrate the theoretical analysis.

关键词： current sharing improvement resistors digital control control engineering computing lookup table method multiphase interleaved DC-DC buck converter DCR control of electric power systems table lookup autotuning scheme digital control technique Power electronics, supply and supervisory circuits current sensing technique direct current resistor calibration DC-DC power convertors

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AN EXPERT SYSTEMS-APPROACH TO controlLER-DESIGN

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IEE PROCEEDINGS-D control THEORY AND APPLICATIONS 1990年第6期137卷 367-373页

作者： TEBBUTT, CD Department of Electrical and Electronic Engineering University of Cape Town Cape Town South Africa

An expert system has been used to build an intelligent interface to a recently developed CACSD technique for the design of linear controllers. This combination allows the design to be specified in terms of time and frequency domain constraints on the closed-loop transfer functions, and provides the designer with assistance in formulating a reasonable specification and in dealing with constraint conflicts.

关键词： Expert systems and other AI software and techniques control engineering computing frequency domain constraints frequency-domain synthesis linear systems control system CAD linear controllers expert systems time-domain synthesis closed-loop transfer functions control system analysis and synthesis methods time domain synthesis

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DIGITAL controlLER FOR THYRISTOR CURRENT SOURCE

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IEE PROCEEDINGS-B ELECTRIC POWER APPLICATIONS 1985年第1期132卷 46-52页

作者： LUO, FL JACKSON, RD HILL, RJ Department of Engineering University of Cambridge Cambridge UK

This paper describes the circuits and algorithms used in a microprocessor-controlled AC/DC thyristor convertor to implement a wide-bandwidth closed-loop current source. The convertor consists of two three-phase bridge circuits for four-quadrant operation, with direct digital control using a M6809 microprocessor. The timing pulse generator is linked to the supply frequency via a phase locked loop, making the system insensitive to supply frequency variation. The use of proportional-plus-integral (PI) control algorithms leads to fast responses to step changes in reference input. Results from constant-gain PI controllers are compared in the paper with theoretical responses based on approximate z-transform analysis to obtain optimum parameters for various modes of operation. In addition, results are presented from a simple variable-gain adaptive controller which adjusts the controller parameters depending on the reference change and operating point.

关键词： two term control timing pulse generator Power convertors and power supplies to apparatus AC/DC thyristor convertor direct digital control variable-gain adaptive controller two-term control digital control thyristor applications control of electric power systems M6809 microprocessor three-phase bridge circuits control engineering computing controllers phase locked loop computerised control power convertors wide-bandwidth closed-loop current source supply frequency controllers

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Improving model predictive control arithmetic robustness by Monte Carlo simulations

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IET control THEORY AND APPLICATIONS 2012年第8期6卷 1064-1070页

作者： Vouzis, P. D. Collange, S. Arnold, M. G. Kothare, M. V. Carnegie Mellon Univ Dept Chem Engn Pittsburgh PA 15213 USA Ecole Normale Super Lyon LIP F-69364 Lyon 07 France Lehigh Univ Dept Comp Sci & Engn Bethlehem PA 18015 USA

Model predictive control (MPC) is an optimisation-based algorithm which usually requires a numerical method to calculate the solution of the problem. Inherently, numerical methods for optimisation problems are implemented on a finite-precision hardware platform and are subject to the appearance of numerical instabilities of catastrophic cancellation and ill-conditioned matrices. These anomalies are difficult to detect and overcome, and for safety-critical applications, it is essential to have a mechanism that can at least issue a warning when an arithmetic instability occurs. Towards this direction, Monte Carlo arithmetic (MCA) for the floating-point (FP) number system has been used for both detection and mitigation of catastrophic cancellation and ill-conditioned matrices. An alternative to FP is the Logarithmic Number System (LNS) that recently has been proposed for the real-time hardware implementation of embedded MPC. In this study the authors present the adaptation of MCA to LNS for detecting and mitigating catastrophic cancellation, forming the Monte Carlo Logarithmic Number System (MCLNS). An inherent drawback of MCA is the accuracy deterioration which is a direct consequence of the randomisation in the arithmetic operations. Additionally, multiple simulations of the system result in performance deterioration equal to the number of simulations. Using off-line simulations it is possible to determine the necessary hardware requirements to achieve desired accuracy under performance constraints. These trade-offs are studied and analysed for an MPC algorithm, and the hardware implementation cost of MCLNS is quantified by synthesis on a Xilinx Virtex-IV FPGA.

关键词： mathematics computing Optimisation techniques MPC algorithm Xilinx Virtex-IV FPGA Mathematics computing finite-precision hardware platform predictive control Digital arithmetic methods floating point arithmetic catastrophic cancellation optimisation-based algorithm control engineering computing Monte Carlo logarithmic number system model predictive control arithmetic control engineering computing Optimal control Monte Carlo methods floating-point number system optimisation ill-conditioned matrices

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Toward Improving Confidence in Autonomous Vehicle Software: A Study on Traffic Sign Recognition Systems

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COMPUTER 2021年第8期54卷 66-76页

作者： Aslansefat, Koorosh Kabir, Sohag Abdullatif, Amr Vasudevan, Vinod Papadopoulos, Yiannis Univ Hull Dept Comp Sci & Technol Kingston Upon Hull HU6 7RX N Humberside England Univ Bradford Fac Engn & Informat Bradford BD7 1DP W Yorkshire England

This article proposes an approach named SafeML II, which applies empirical cumulative distribution function-based statistical distance measures in a designed hurnon-in-the-loop procedure to ensure the safety of machin... 详细信息

关键词： control engineering computing Learning Artificial Intelligence Mobile Robots Pattern Classification Remotely Operated Vehicles Road Traffic control Road Vehicles Statistical Distributions Traffic engineering computing Autonomous Vehicle Software Traffic Sign Recognition Systems Safe ML II Empirical Cumulative Distribution Function Machine Learning Based Classifiers Statistical Distance Measures Human In The Loop Procedure Software Safety Software Measurement Autonomous Vehicles

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Automatic tuning method for the design of supplementary damping controllers for flexible alternating current transmission system devices

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IET GENERATION TRANSMISSION & DISTRIBUTION 2009年第10期3卷 919-929页

作者： de Oliveira, R. V. Kuiava, R. Ramos, R. A. Bretas, N. G. Fed Technol Univ Parana Electromech Engn Dept BR-85503390 Pato Branco PR Brazil Univ Sao Paulo Engn Sch Sao Carlos BR-13566590 Sao Carlos SP Brazil

The design of supplementary damping controllers to mitigate the effects of electromechanical oscillations in power systems is a highly complex and time-consuming process, which requires a significant amount of knowledge from the part of the designer. In this study, the authors propose an automatic technique that takes the burden of tuning the controller parameters away from the power engineer and places it on the computer. Unlike other approaches that do the same based on robust control theories or evolutionary computing techniques, our proposed procedure uses an optimisation algorithm that works over a formulation of the classical tuning problem in terms of bilinear matrix inequalities. Using this formulation, it is possible to apply linear matrix inequality solvers to find a solution to the tuning problem via an iterative process, with the advantage that these solvers are widely available and have well-known convergence properties. The proposed algorithm is applied to tune the parameters of supplementary controllers for thyristor controlled series capacitors placed in the New England/New York benchmark test system, aiming at the improvement of the damping factor of inter-area modes, under several different operating conditions. The results of the linear analysis are validated by non-linear simulation and demonstrate the effectiveness of the proposed procedure.

关键词： electromechanical oscillations control of electric power systems New England-New York benchmark test system Linear algebra (numerical analysis) iterative methods Optimisation techniques flexible AC transmission systems a.c. transmission linear matrix inequalities Power convertors and power supplies to apparatus Power system control linear matrix inequality supplementary damping controller design automatic tuning method damping flexible alternating current transmission system device thyristor controlled series capacitors control system analysis and synthesis methods optimisation algorithm optimisation Interpolation and function approximation (numerical analysis) control system synthesis control engineering computing power engineering computing bilinear matrix inequality iterative process power transmission control Power engineering computing power capacitors thyristor applications power systems

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Stochastic observer-based guaranteed cost control for networked control systems with packet dropouts

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IET control THEORY AND APPLICATIONS 2008年第11期2卷 980-989页

作者： Fang, X. Wang, J. Shanghai Jiao Tong Univ Dept Automat Shanghai 200240 Peoples R China

The observer-based guaranteed cost control problem in networked control systems with random data packet dropouts is dealt with. The sensor-to-controller and controller-to-actuator packet dropouts are both modelled by two mutually independent stochastic variables satisfying the Bernoulli binary distribution. A new observer is designed to estimate the states and system input simultaneously by constructing an augmented system in which the original system input is regarded as a new state. Based on this observer, a guaranteed cost controller is designed such that the closed-loop system is stochastically exponentially mean-square stable and the cost function value is not more than a specified upper bound. The controller design problem is transformed to a convex optimisation problem that can be solved by a linear matrix inequality approach. A numerical example is given to illustrate the effectiveness of the proposed design method.

关键词： controller-to-actuator packet dropout linear matrix inequalities mean square error methods convex optimisation problem closed loop systems linear matrix inequality observers closed-loop system Bernoulli binary distribution convex programming exponential mean-square stability mutually independent stochastic variable networked control system asymptotic stability random processes controller design problem stochastic processes random data packet dropout control system synthesis sensor-to-controller packet dropout control engineering computing guaranteed cost control design stochastic observer

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