Development of the UMAC-based control system with application to 5-axis ultraprecision micromilling machines

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Increasing demands from end users in the fields of optics, defence, automotive, medical, aerospace, etc. for high precision 3D miniaturized components and microstructures from a range of materials have driven the development in micro and nano machining and changed the manufacturing realm. Conventional manufacturing processes such as chemical etching and LIGA are found unfavourable or limited due to production time required and have led mechanical micro machining to grow further. Mechanical micro machining is an ideal method to produce high accuracy micro components and micro milling is the most flexible enabling process and is thus able to generate a wider variety of complex micro components and microstructures. Ultraprecision micromilling machine tools are required so as to meet the accuracy, surface finish and geometrical complexity of components and parts. Typical manufacturing requirements are high dimensional accuracy being better than 1 micron, flatness and roundness better than 50 nm and surface finish ranging between 10 and 50 nm. Manufacture of high precision components and parts require very intricate material removal procedure. There are five key components that include machine tools, cutting tools, material properties, operation variables and environmental conditions, which constitute in manufacturing high quality components and parts. End users assess the performance of a machine tool based on the dimensional accuracy and surface quality of machined parts including the machining time. In this thesis, the emphasis is on the design and development of a control system for a 5-axis bench-type ultraprecision micromilling machine- Ultra-Mill. On the one hand, the developed control system is able to offer high motion and positioning accuracy, dynamic stiffness and thermal stability for motion control, which are essential for achieving the machining accuracy and surface finish desired. On the other hand, the control system is able to undertake in-process inspection and condition monitoring of the machine tool and process. The control of multi-axis precision machines with high-speed and high-accuracy motions and positioning are desirable to manufacture components with high accuracy and complex features to increase productivity and maintain machine stability, etc. The development of the control system has focused on fast, accurate and robust positioning requirements at the machine system design stage. Apart from the mechanical design, the performance of the entire precision systems is greatly dependent on diverse electrical and electronics subsystems, controllers, drive instruments, feedback devices, inspection and monitoring system and software. There are some variables that dynamically alter the system behaviour and sensitivity to disturbance that are not ignorable in the micro and nano machining realm. In this research, a structured framework has been developed and integrated to aid the design and development of the control system. The framework includes critically reviewing the state of the art of ultraprecision machining tools, understanding the control system technologies involved, highlighting the advantages and disadvantages of various control system methods for ultraprecision machines, understanding what is required by end-users and formulating what actually makes a machine tool be an ultraprecision machine particularly from the control system perspective. In the design and development stage, the possession of mechatronic know-how is essential as the design and development of the Ultra-Mill is a multidisciplinary field. Simulation and modelling tool such as Matlab/Simulink is used to model the most suitable control system design. The developed control system was validated through machining trials to observe the achievable accuracy, experiments and testing of subsystems individually (slide system, tooling system, monitoring system, etc.). This thesis has successfully demonstrated the design and development of the control system for a 5-axis ultraprecision machine tool- Ultra-Mill, with high performance characteristics, fast, accurate, precise, etc. for motion and positioning, high dynamic stiffness, robustness and thermal stability, whereby was provided and maintained by the control system

Destination image evolvement through experiential marketing / Nor Aminin Mohd Khalid, Rosmimah Mohd Roslin

This qualitative study is an exploratory attempt at understanding destination image through the writings of the travel writers who have undergone the familiarisation or fam programs organised by Tourism Malaysia. The idea behind the program is for the writers to experience first-hand specific destinations in Malaysia and then expressed their experiences through their travel writings. The data in the form of the travel articles were collected with the assistance of Tourism Malaysia based on the suggested criteria established. This study established that it was possible to derive destination image by interpreting the depth of the articles and through the expressions of the travel writers who very often narrated their experiences coherently through vivid depictions and emotions. It is suggested that future studies further test the evolving themes through empirical analyses that are more conclusive and statistically proven

Development of the UMAC-based control system with application to 5-axis ultraprecision micromilling machines

Increasing demands from end users in the fields of optics, defence, automotive, medical, aerospace, etc. for high precision 3D miniaturized components and microstructures from a range of materials have driven the development in micro and nano machining and changed the manufacturing realm. Conventional manufacturing processes such as chemical etching and LIGA are found unfavourable or limited due to production time required and have led mechanical micro machining to grow further. Mechanical micro machining is an ideal method to produce high accuracy micro components and micro milling is the most flexible enabling process and is thus able to generate a wider variety of complex micro components and microstructures. Ultraprecision micromilling machine tools are required so as to meet the accuracy, surface finish and geometrical complexity of components and parts. Typical manufacturing requirements are high dimensional accuracy being better than 1 micron, flatness and roundness better than 50 nm and surface finish ranging between 10 and 50 nm. Manufacture of high precision components and parts require very intricate material removal procedure. There are five key components that include machine tools, cutting tools, material properties, operation variables and environmental conditions, which constitute in manufacturing high quality components and parts. End users assess the performance of a machine tool based on the dimensional accuracy and surface quality of machined parts including the machining time. In this thesis, the emphasis is on the design and development of a control system for a 5-axis bench-type ultraprecision micromilling machine- Ultra-Mill. On the one hand, the developed control system is able to offer high motion and positioning accuracy, dynamic stiffness and thermal stability for motion control, which are essential for achieving the machining accuracy and surface finish desired. On the other hand, the control system is able to undertake in-process inspection and condition monitoring of the machine tool and process. The control of multi-axis precision machines with high-speed and high-accuracy motions and positioning are desirable to manufacture components with high accuracy and complex features to increase productivity and maintain machine stability, etc. The development of the control system has focused on fast, accurate and robust positioning requirements at the machine system design stage. Apart from the mechanical design, the performance of the entire precision systems is greatly dependent on diverse electrical and electronics subsystems, controllers, drive instruments, feedback devices, inspection and monitoring system and software. There are some variables that dynamically alter the system behaviour and sensitivity to disturbance that are not ignorable in the micro and nano machining realm. In this research, a structured framework has been developed and integrated to aid the design and development of the control system. The framework includes critically reviewing the state of the art of ultraprecision machining tools, understanding the control system technologies involved, highlighting the advantages and disadvantages of various control system methods for ultraprecision machines, understanding what is required by end-users and formulating what actually makes a machine tool be an ultraprecision machine particularly from the control system perspective. In the design and development stage, the possession of mechatronic know-how is essential as the design and development of the Ultra-Mill is a multidisciplinary field. Simulation and modelling tool such as Matlab/Simulink is used to model the most suitable control system design. The developed control system was validated through machining trials to observe the achievable accuracy, experiments and testing of subsystems individually (slide system, tooling system, monitoring system, etc.). This thesis has successfully demonstrated the design and development of the control system for a 5-axis ultraprecision machine tool- Ultra-Mill, with high performance characteristics, fast, accurate, precise, etc. for motion and positioning, high dynamic stiffness, robustness and thermal stability, whereby was provided and maintained by the control system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A Paradigm Shift from Optimal Play to Mental Comfort: A Perspective from the Game Refinement Theory

The game refinement theory focuses on the game designer perspective, where its application in various types of games provides evidence of the occurring paradigm shift. Utilizing the logistical model of game outcome uncertainty, it provides a platform for incorporating gamified experience observed in games to be adopted in domains outside of game while retaining the context of the game. Making games as a testbed, the implications of the game refinement theory have been observed in the educational and business perspective, while further explored its utility in interpreting some states of the human mind. In addition, a holistic view of design in games and in the real-world environments was discussed, where the prospects of the game refinement theory were also highlighted

Sensitivity Identification of Low-frequency Cantilever Fibre Bragg Grating Accelerometer

Vibration response of low-frequency cantilever fibre Bragg grating (FBG) accelerometer produced by Euler–Bernoulli model (namely FBG-MM model) is found to be frequency-dependent, unsimilar to SDOF model. Therefore, the sensitivity of the cantilever FBG accelerometer could not be identified using polynomial or basic fitting methods. This paper presents the use of cascade-forward backpropagation neural network (CFB) to predict the sensitivity of the cantilever FBG accelerometer in a "black box", which refers to the behaviour of the deep neural network. The inputs of the network are maximum base accelerations and forcing frequencies, which was set between 20 and 90 Hz (below than the first fundamental frequency of the proposed FBG accelerometer), while the output is the wavelength shift. The validation results show that the wavelength shift predicted by the trained CFB demonstrates good agreement with the FBG-MM, with the input parameter within the range of that used in training process. In addition, results also show that the trained CFB would be invalid if the input parameter is out of the range of that used in training process. In real acceleration measurement, since the forcing frequency is unknown beforehand, the trained CFB must be re-trained by considering the maximum base accelerations are embedded with forcing frequencies

An Enhanced Artificial Immune System Approach For Assembly Line Balancing Problem Through Shifting Bottleneck Identification

The manufacturing industry has evolved rapidly in the past few years, due to the global competitive economy, high-quality market demands, and customized products with the lowest possible costs. This is achieved by partitioning the workloads among the available resource to obtain an equal amount of workloads in the assembly line system, which defines the assembly line balancing (ALB) problem. The most prominent ALB problem is the simple assembly line balancing (SALB) problem which has been utilized for decades to provide a basis for testing different approaches. Despite varieties of computational techniques have addressed the ALB problem, which can be categorized as exact, heuristic, and meta-heuristic approaches, little work had been done on SALB-E problem due to its difficulty of obtaining the optimal solutions. Additionally, bottlenecks can still occur during the assembly operations that affect the production quality and induce unnecessary costs. Identifying and optimizing machines with the likelihood of the next operation bottleneck had been rarely addressed in the assembly line especially when it shifts from one machine to another (called shifting bottleneck). This study propose an effective computational approach to address the SALB-E problem through the shifting bottleneck identification. A bio-inspired approach had been frequently adopted for handling complex and combinatorial optimization problem through a simple yet effective manner. As such, a computational method, known as artificial immune system (AIS) approach, had been proposed

Optimizing Crowd Evacuation In The Emergency Route Planning Problem

Situasi bencana, yang berlaku secara semula jadi (kebakaran, banjir, taufan) atau buatan manusia (contohnya pengeboman pengganas, tumpahan bahan kimia, dan lain-lain), telah meragut ribuan nyawa, mencetuskan keperluan untuk pemindahan kecemasan. Biasanya, mengoptimumkan pelan pemindahan kecemasan melibatkan berkesanan pemodelan orang ramai dan pemilihan laluan, dimana pelan yang optimum penting dalam masalah perancangan laluan kecemasan (ERP). Pelbagai pendekatan ERP telah dibangunkan dimana diklasifikasikan kepada pendekatan matematik, keputusan sokongan, heuristik, dan meta-heuristik. Ulasan kesusasteraan menyeluruh telah menunjukkan kepentingan untuk merapatkan jurang antara pemodelan dan pemilihan laluan, di mana di mana pendekatan bersepadu dan berdaya maju diperlukan. Dalam kajian ini, satu perancangan pemindahan rangka kerja bersepadu menggunakan model pemindahan orang ramai dan sistem imun (AIS) algoritma tiruan, yang dipanggil iEvaP, telah dicadangkan. iEvaP telah disahkan terhadap Lu et al. (2003) dan parameternya telah ditentukan untuk prestasi yang optimum. Disastrous situations, either natural (e.g. fires, floods, hurricane) or man-made (e.g. terrorist bombings, chemical spills, etc.), have claimed the lives of thousands, triggering the needs for emergency evacuation. Typically, optimizing an emergency evacuation plan involves both the effectiveness in crowd modelling and route selection, where an optimum evacuation plan is vital in the emergency route planning (ERP) problem. Various ERP approaches have been developed which are classified into mathematical, decision-support, heuristic, and meta-heuristic approaches. Exhaustive literature reviews have shown the significance of bridging the gap between modeling and routing, where an integrated and viable approach is needed. In this study, an integrated evacuation planning framework utilizing crowd evacuation model and an artificial immune system (AIS) algorithm, called iEvaP, was proposed. iEvaP was validated against Lu et al. (2003) and its parameters were calibrated for optimum performance

Ciri fizikokimia filem boleh makan dan filem polietilena bagi ubi keledek (Ipomoea batatas) goreng

Penyelidikan dijalankan bagi menilai kesan penggunaan filem boleh makan dan filem polietilena (PE) sebagai bahan penyalut untuk ubi keledek (Ipomoea batatas) goreng. Kepingan ubi keledek disalut dengan lapisan filem boleh makan yang terdiri daripada 0.045 g/mL selulosa metil (MC), 0.045 g/mL selulosa hidroksipropil metil (HPMC) dan 0.16 g/mL jagung zein (CZ) sebelum digoreng di dalam minyak sawit pada suhu 170-180°C selama 3 min. Manakala ubi keledek juga disalut dengan filem tak boleh makan iaitu polietilena (PE) (nisbah PE kepada minyak 1:100 g/g) sebagai perbandingan. Ubi goreng tanpa salutan filem digunakan sebagai sampel kawalan. Ciri fizikokimia ubi goreng bersalut dianalisa. Keputusan menunjukkan semua filem melekat pada permukaan ubi setelah digoreng. Penggunaan filem CZ menjadikan permukaan filem licin dan wujud tanpa sebarang retakan. Filem MC pula memberi lapisan permukaan yang tidak rata tetapi menyaluti permukaan sampel dengan sekata. Tambahan pula, ubi bersalut MC menunjukkan peratusan lemak paling sedikit (13.6%) selain kandungan kelembapan yang paling tinggi (17.5%) berbanding sampel lain. Secara keseluruhan, MC merupakan filem yang terbaik untuk mengekalkan kelembapan bahan goreng dan mengurangkan penyerapan lemak

Stabilization of convective instability in micropolar fluid model by feedback control strategy subjected to internal heat source

This investigation reports on a stability analysis of Rayleigh-Benard convection in a horizontal of micropolar fluid layer heated from below. The effect of a feedback control strategy on the onset of steady convection in the presence of internal heat source is investigated theoretically using Galerkin technique. The eigenvalues are obtained for free-free, rigid-rigid, free-rigid boundary combination with isothermal temperature boundary condition. The influence of various micropolar parameters on the onset of convection has also been analyzed. The onset of motion is found to depend on the feedback control parameter, K and internal heat source, Q and the micropolar parameter Ni

The stability of soret induced convection in doubly diffusive fluid layer with feedback control

Linear stability analysis is performed to study the Soret induced convection in a doubly diffusive fluid layer heated from below. The effect of a feedback control on the onset of steady convection is investigated theoretically using Galerkin technique. The eigenvalues are obtained for Free-Free, Rigid-Rigid, Rigid-Free boundaries combined with isothermal temperature boundary condition. The influence of various doubly diffusive parameters on the onset of convection has also been analyzed. It is found that the onset of motion can be stabilized by using the feedback control in all cases