Identification of Frequency Ranges for Subharmonic Oscillations in a Relay Feedback System

This paper examines the behaviour of a single loop relay feedback system (RFS) which is driven by an external signal. It is well known that such a RFS exhibits a variety of oscillation patterns including forced and subharmonic oscillations (SO). This paper focuses on the conditions for SO. It will be shown that for an external signal with a fixed amplitude, it is possible for SO with different orders to occur simply by changing the frequency of the external signal. Similarly, for an external signal with a fixed frequency, it is possible for SO with different orders to occur when the amplitude of the external signal is varied. The conditions under which these different scenarios will occur are explored. An analysis of these conditions identifies the frequency ranges where certain orders of SO are possible for a given amplitude of the external signal. The effects of the initial conditions on the SO are illustrated and discussed. Simulation studies are presented to illustrate the result

Supervising multidisciplinary final-year engineering students to develop CubeSats with an innovative project management method

10.1109/FIE.2018.86587802018 IEEE Frontiers in Education Conference (FIE)2018-Octobe

Limit cycles in high-resolution quantized feedback systems

In this paper, the existence of limit cycles in high-resolution quantized feedback systems is examined. It is well known that the relay and the quantized feedback systems exhibit self-oscillations, due to their switching nature. However, the quantizer is a more general nonlinearity as compared to the relay, due to its switching at multiple discrete levels. An extension of periodic switching conditions uncovers the existence of self-oscillations in some systems under high quantization resolution. Multiple limit cycle solutions of switching instants and periods have been found, depending on the initial states of the system. Further analysis on the stability of the limit cycle via the Jacobian of the Poincaré map reveals numerical bounds on the quantization step size for a stable limit cycle. Analytical results on the existence of limit cycles in first and second order systems are also presented

Stability Analysis of High-Resolution Quantized Feedback Systems

In this paper, we study the stability of a high resolution quantized feedback system. It is well known that a quantized feedback system can be stabilised by increasing the resolution of the quantizer. However, limit cycles have also been found under certain conditions at high resolution. These necessary and sufficient conditions for the existence of limit cycles are examined. Solutions for the limit cycle period and switching instants obtained via the inverse-free Newton's method are used to assess the stability of the limit cycle under high resolution with the Poincaré map. A bound on the quantization resolution is identified for a stable limit cycle. Analytical results on the existence of limit cycles in first and second order systems are also presented

Nonlinear adaptive controller for a pH neutralization process

Proceedings of the American Control Conference42250-2254PRAC

The NUS hand posture datasets II

doi:10.25540/AWJS-GMJBThe NUS hand posture datasets I & I

The NUS hand posture datasets I

doi:10.25540/6PR9-R5HSThe NUS hand posture datasets I & I

Computational intelligence in multi-feature visual pattern recognition: hand posture and face recognition using biologically inspired approaches

This book presents a collection of computational intelligence algorithms that addresses issues in visual pattern recognition such as high computational complexity, abundance of pattern features, sensitivity to size and shape variations and poor performance against complex backgrounds. The book has 3 parts. Part 1 describes various research issues in the field with a survey of the related literature. Part 2 presents computational intelligence based algorithms for feature selection and classification. The algorithms are discriminative and fast. The main application area considered is hand posture recognition. The book also discusses utility of these algorithms in other visual as well as non-visual pattern recognition tasks including face recognition, general object recognition and cancer / tumor classification. Part 3 presents biologically inspired algorithms for feature extraction. The visual cortex model based features discussed have invariance with respect to appearance and size of the hand, and provide good inter class discrimination. A Bayesian model of visual attention is described which is effective in handling complex background problem in hand posture recognition. The book provides qualitative and quantitative performance comparisons for the algorithms outlined, with other standard methods in machine learning and computer vision. The book is self-contained with several figures, charts, tables and equations helping the reader to understand the material presented without instruction

An application of genetic algorithm for designing a Wiener-model controller to regulate the pH value in a pilot plant

Proceedings of the IEEE Conference on Evolutionary Computation, ICEC21055-106

Computational Intelligence in Multi-Feature Visual Pattern Recognition : Hand Posture and Face Recognition using Biologically Inspired Approaches

XIII, 138 p. 50 illus., 25 illus. in color.onlin