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Articles 391 - 420 of 498

Full-Text Articles in Engineering

Collaborative Management Of Web Ontology Data With Flexible Access Control, Jie Lu, Chao Wang, Guangquan Zhang, Jun Ma Jan 2010

Collaborative Management Of Web Ontology Data With Flexible Access Control, Jie Lu, Chao Wang, Guangquan Zhang, Jun Ma

Faculty of Engineering and Information Sciences - Papers: Part A

The creation and management of ontology data on web sites (e.g. instance data that is used to annotate web pages) is important technical support for the growth of the semantic web. This study identifies some key issues for web ontology data management and describes an ontology data management system, called robinet, to perform the management. This paper presents the structure of the system and introduces a Web ontology data management model that enables a flexible access control mechanism. This model adds rules into the robinet system to utilize the semantics of ontology for controlling the access to ontology data. The …

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Humanoid Human-Like Reaching Control Based On Movement Primitives, Minh Tuan Tran, Philippe Souères, Michel Taix, Manish Sreenivasa, Christophe Halgand Jan 2010

Humanoid Human-Like Reaching Control Based On Movement Primitives, Minh Tuan Tran, Philippe Souères, Michel Taix, Manish Sreenivasa, Christophe Halgand

Faculty of Engineering and Information Sciences - Papers: Part B

This paper deals with the problem of generating realistic human-like reaching movements from a small set of movement primitives. Two kinds of movement databases are used as reference. The first one is obtained numerically, by applying biological principles of motor control on the dynamic model of the robot arm. The second one is obtained by recording reaching movements of human subjects. From these databases, primitives are extracted and analyzed by using Principal Component Analysis. An original generalization method is then proposed for generating movements that did not belong to the initial database. We show that twenty primitives allow to produce …

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Hrp-2 Plays The Yoyo: From Human To Humanoid Yoyo Playing Using Optimal Control, Katja Mombaur, Manish Sreenivasa Jan 2010

Hrp-2 Plays The Yoyo: From Human To Humanoid Yoyo Playing Using Optimal Control, Katja Mombaur, Manish Sreenivasa

Faculty of Engineering and Information Sciences - Papers: Part B

Yoyo playing may seem easy for a human, but it is a challenging problem for a humanoid robot. This paper presents an approach to generate yoyo motions for the humanoid robot, HRP-2, based on motion recorded from human yoyo playing, dynamical models and numerical optimal control techniques. We recorded vertical yoyo playing of 4 subjects measuring yoyo height and rotation angle as well as the corresponding hand motions. A detailed multi-phase yoyo model with impact collisions and control patterns of human yoyo playing were identified from these measurements. Based on this knowledge, reliable yoyo motions within the feasibility ranges of …

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Harmonic Elimination Control Of A Five-Level Dc-Ac Cascaded H-Bridge Hybrid Inverter, Georgios S. Konstantinou, Sridhar R. Pulikanti, Vassilios G. Agelidis Jan 2010

Harmonic Elimination Control Of A Five-Level Dc-Ac Cascaded H-Bridge Hybrid Inverter, Georgios S. Konstantinou, Sridhar R. Pulikanti, Vassilios G. Agelidis

Faculty of Engineering and Information Sciences - Papers: Part A

A five-level hybrid cascaded inverter operating under selective harmonic elimination (SHE) pulse-width modulation (PWM) control is discussed in this paper. The topology is a cascaded connection of a conventional three-phase, two-level inverter and an H-bridge module for each phase with a single DC-source. The topology boosts the output voltage within limits and with no additional DC-DC converters. However, such boosting feature depends on the control of the floating capacitor voltage and the load power factor. The regulation of the floating capacitor for the given modulation strategy is also analyzed. Experimental results taken from a single-phase laboratory prototype are presented to …

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Analysis And Design Of A Feedback Controlled Adaptive Pneumatic Cast, Susan Renee Mueller Jan 2010

Analysis And Design Of A Feedback Controlled Adaptive Pneumatic Cast, Susan Renee Mueller

Electronic Theses and Dissertations

A pneumatic system with PID control for an actively controlled cast is designed. The cast is intended to aid healing of diabetic foot ulcers by relieving pressure from the sole of a patient's foot and distributing it to the calf. This is accomplished by a pneumatic system which maintains set pressure in multiple air bladders. The research began by defining an electrical circuit analogous to a single supply subsystem. Tests are performed to determine the coefficients for each component. These coefficients are used in a mathematical model to better understand the response of the system to pressure input. A controller …

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Inverse Optimal Control As A Tool To Understand Human Yoyo Playing, Katja Mombaur, Manish Sreenivasa Jan 2010

Inverse Optimal Control As A Tool To Understand Human Yoyo Playing, Katja Mombaur, Manish Sreenivasa

Faculty of Engineering and Information Sciences - Papers: Part B

This paper presents an inverse optimal control approach to identify objective functions of human motion from motion capture measurements. We apply it to analyze human yoyo playing. Yoyo playing may seem easy to us to learn but it is a challenging problem from a mechanical point of view involving a hybrid dynamics model. We recorded vertical yoyo playing of humans measuring yoyo height and rotation angle as well as the corresponding hand motions. Results of inverse optimal control are presented showing a mixed criterion of cycle time and terms depending on yoyo and hand acceleration and velocity.

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The Comparison Between Nanostructure Control And Other Modifications To Improve The Electrochemical Performance Of Sno, Yong-Mook Kang, Min-Sik Park, Hua-Kun Liu, S. X. Dou Jan 2010

The Comparison Between Nanostructure Control And Other Modifications To Improve The Electrochemical Performance Of Sno, Yong-Mook Kang, Min-Sik Park, Hua-Kun Liu, S. X. Dou

Faculty of Engineering - Papers (Archive)

With an advent of the ubiquitous era, the demand for rechargeable batteries with a higher energy density is getting more and more critical. It is because applications are emerging such as electric vehicles and various types of portable electronic devices. Carbonaceous materials are commonly adopted as the anode material for commercial lithium-ion secondary batteries because it can reversibly intercalate or de-intercalate Li ion. However, low capacity of carbon has become a limiting factor in wider applications, and high capacity alternative to carbonaceous material has thus been sought for. Even if tin and silicon have been considered as one of the …

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The Control Of Time-Dependent Buckling Patterns In Thin Confined Elastomer Film, Brad Winton, Mihail Ionescu, S X. Dou Jan 2010

The Control Of Time-Dependent Buckling Patterns In Thin Confined Elastomer Film, Brad Winton, Mihail Ionescu, S X. Dou

Australian Institute for Innovative Materials - Papers

Low energy metal ion implantation has been used to combine an easy “bottom-up” way of creating and tuning different topographic structures on submicron to micrometer scales with the embedding of a metallic element-rich functionalized layer at the surface for a variety of scientific and technological applications. The self-organizing and complex patterns of functionalized topographic structures are highly dependent on the implanted metal ion species, variations in the geometric confinement of the buckled areas on the larger unmodified elastomer film, and the boundary conditions of the buckled regions. Systematic investigations of these dependencies have been carried out via optical and atomic …

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The Harmonic Distortion Reduction Of Phase-Angle Fired Scrs Feeding A Resistive Load Using Fuzzy Logic, Matthew A. Clark Jan 2010

The Harmonic Distortion Reduction Of Phase-Angle Fired Scrs Feeding A Resistive Load Using Fuzzy Logic, Matthew A. Clark

Browse all Theses and Dissertations

High power silicon controlled rectifiers (SCR) are used in the application of infrared radiation testing. A case study has been performed on a department of defense facility utilizing SCRs to transfer electrical energy to thermal energy. The facility is capable of generating up to 5000 °F across large cross-sectional areas, requiring tens of megawatts of power. The combination of high power, unbalanced loads, and SCR switching generate high harmonic disturbances that offer significant challenges for conventional linear control systems. In addition, unbalanced three-phase distribution systems are difficult to model, specifically during switching transients. Fuzzy logic is used to characterize the …

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On-Line Realtime Water Quality Monitoring And Control For Swimming Pools, Paul Duffy, Gerard Woods, Sean O'Hogain, James Walsh, C. Caplier Sep 2009

On-Line Realtime Water Quality Monitoring And Control For Swimming Pools, Paul Duffy, Gerard Woods, Sean O'Hogain, James Walsh, C. Caplier

Conference Papers

Effective swimming pool water quality monitoring and control systems are important to safeguard public health and for bather comfort. Most Irish swimming pool monitoring systems rely heavily on manual methods for sampling, testing and data recording of important parameters. Microbiological testing is infrequent and results can often take days. The goal of this research is to develop a water quality monitoring and control system with real time data logging, automatic data analysis, remote monitoring and control, microbiological sampling capabilities and online connectivity. National Instruments hardware and its software package LabView form the basis of the monitoring and control system. Several …

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Microcantilever-Based Force Sensing, Control And Imaging, Reza Saeidpourazar May 2009

Microcantilever-Based Force Sensing, Control And Imaging, Reza Saeidpourazar

All Dissertations

This dissertation presents a distributed-parameters base modeling framework for microcantilever (MC)-based force sensing and control with applications to nanomanipulation and imaging. Due to the widespread applications of MCs in nanoscale force sensing or atomic force microscopy with nano-Newton to pico-Newton force measurement requirements, precise modeling of the involved MCs is essential. Along this line, a distributed-parameters modeling framework is proposed which is followed by a modified robust controller with perturbation estimation to target the problem of delay in nanoscale imaging and manipulation. It is shown that the proposed nonlinear model-based controller can stabilize such nanomanipulation process in a very short …

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Mitigating Crack Propagation In A Highly Maneuverable Flight Vehicle Using Life Extending Control Logic, Mohamed Mostafa Yousef Bassyouny Elshabasy Apr 2009

Mitigating Crack Propagation In A Highly Maneuverable Flight Vehicle Using Life Extending Control Logic, Mohamed Mostafa Yousef Bassyouny Elshabasy

Mechanical & Aerospace Engineering Theses & Dissertations

In this research, life extending control logic is proposed to reduce the cost of treating the aging problem of military aircraft structures and to avoid catastrophic failures and fatal accidents due to undetected cracks in the airframe components. The life extending control logic is based on load tailoring to facilitate a desired stress sequence that prolongs the structural life of the cracked airframe components by exploiting certain nonlinear crack retardation phenomena. The load is tailored to include infrequent injections of a single-cycle overload or a single-cycle overload and underload. These irregular loadings have an anti-intuitive but beneficial effect, which has …

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Q-Learning Algorithm For Navigation Control Of Autonomous Blimp, Yiwei Liu, Zengxi Pan, David A. Stirling, Fazel Naghdy Jan 2009

Q-Learning Algorithm For Navigation Control Of Autonomous Blimp, Yiwei Liu, Zengxi Pan, David A. Stirling, Fazel Naghdy

Faculty of Engineering - Papers (Archive)

In this research, an autonomous control system for blimp navigation was developed using reinforcement learning algorithm. The aim of this research is to provide a blimp the capability to approach a goal position autonomously in an environment, where the dynamical models of the blimp and the environment are unknown. Webots™ Robotics Simulator (WRS) was used to simulate and evaluate the control strategy obtained through a one-step Q-learning method. The simulation data generated via WRS were then processed and analysed within MATLAB. The simulation results showed that the control policy acquired from Q-learning is much more effective compared to the traditional …

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Control Of Autonomous Airship, Yiwei Liu, Zengxi Pan, David A. Stirling, Fazel Naghdy Jan 2009

Control Of Autonomous Airship, Yiwei Liu, Zengxi Pan, David A. Stirling, Fazel Naghdy

Faculty of Engineering - Papers (Archive)

Scientific research and development on the control of autonomous airship have shown a significant growth in recent years. New applications appear in the areas such as freight carrier, advertising, monitoring, surveillance, transportation, military and scientific research. The control of Autonomous airship is a very important problem for the aerial robots research. In this paper, the previous research on the control of autonomous blimp is reviewed, Several popular control methods are categorized and discussed in detail. Then an intelligent navigation control method, reinforcement learning control, is introduced in the autonomous blimp which was used for 2007 UAV Outback Challenge. The future …

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Process Control And Automation Developments In Welding, J Norrish Jan 2009

Process Control And Automation Developments In Welding, J Norrish

Faculty of Engineering - Papers (Archive)

With an international shortage of skilled welders and concerns about exposure of personnel to welding hazards it is appropriate to consider how joining processes can be simplified and automated. The paper reviews the process control techniques which have been applied to enhance the productivity and quality of welded joints. It seeks to explain the influence of power source design and computer control on these developments. In particular it will address the real time control of short arc GMAW and explain how by modulation of the transient electrical properties and high speed wire feed oscillation process performance has enhanced in several …

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A Control Strategy For Output Maximisation Of A Pmsg-Based Variable-Speed Wind Turbine, M E. Haque, K M. Muttaqi, M Negnevitsky Jan 2009

A Control Strategy For Output Maximisation Of A Pmsg-Based Variable-Speed Wind Turbine, M E. Haque, K M. Muttaqi, M Negnevitsky

Faculty of Engineering and Information Sciences - Papers: Part A

This paper presents a control strategy for output maximisation of a direct drive permanent magnet synchronous generator (PMSG)-based small-scale variable-speed wind turbine. The control topology uses a single switch three-phase switch-mode rectifi er and the generator torque, and power is controlled by controlling the switch duty cycle of the switch. To extract maximum power from the wind, the torque reference of the PMSG is calculated from generator speed and wind turbine characteristics. From this torque reference, a current reference is calculated using measured DC link voltage and generator speed. The current error is then used to control the duty cycle …

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Online Performance Evaluation Of Alternative Control Strategies For Building Cooling Water Systems Prior To In-Situ Implementation, Zhenjun Ma, Shengwei Wang, Fu Xiao Jan 2009

Online Performance Evaluation Of Alternative Control Strategies For Building Cooling Water Systems Prior To In-Situ Implementation, Zhenjun Ma, Shengwei Wang, Fu Xiao

Faculty of Engineering - Papers (Archive)

This paper presents the online test and evaluation of the performance of five practical control strategies (fixed set-point control method, fixed approach control method, two near optimal strategies and one optimal strategy) for building cooling water systems to identify the best strategy for future field validation. All of these strategies were tested and evaluated in a simulated virtual environment similar to the situation when they are actually implemented in practice. A virtual building system representing the real building and its central chilling system was developed and used to test the operational performance of the system controlled by different strategies. The …

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Towards The Position Control Of Conducting Polymer Trilayer Bending Actuators With Integrated Feedback Sensor, Stephen John, Gursel Alici, Christopher D. Cook Jan 2009

Towards The Position Control Of Conducting Polymer Trilayer Bending Actuators With Integrated Feedback Sensor, Stephen John, Gursel Alici, Christopher D. Cook

Faculty of Engineering - Papers (Archive)

Conducting polymers have a wide range of reversibly controllable properties, leading to a number of potentially useful devices for robotic applications, including actuators, sensors and batteries. Conducting polymers have the advantages of low weight, low cost, flexibility, small activation potentials (

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Autopilot Development For An Rc Helicopter, Mark C. Arlinghaus Jan 2009

Autopilot Development For An Rc Helicopter, Mark C. Arlinghaus

Browse all Theses and Dissertations

The development of an autopilot system for an RC helicopter presents interesting challengesfrom both a hardware and controls standpoint. The system detailed in this thesis utilizes a 13 state Extended Kalman Filter (EKF) to fuse sensor data and provide a position/velocity/attitude estimate. A novel, state of the art hybrid PID/LQR controller is developed and compared with a full state Linear Quadratic Regulator (LQR). The hybrid controller uses a proportional position, PID velocity outer loop coupled with an inner loop LQR for attitude control. The entire system is developed and implemented in hardware to produce a functional autopilot. The unit was …

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Response To Changes In Key Stimuli Through The Co-Evolution Of Sensor Morphology And Control, Gary Parker, Pramod J. Nathan Sep 2008

Response To Changes In Key Stimuli Through The Co-Evolution Of Sensor Morphology And Control, Gary Parker, Pramod J. Nathan

Computer Science Faculty Publications

Co-evolving a robot’s sensor morphology and control program increases the potential that it can effectively complete its tasks and provides a means for adapting to changes in the environment. In previous work, we presented a learning system where the angle, range, and type of sensors on a hexapod robot, along with the control program, were evolved. Although three sensor stimuli were detectable by the system, it used only two due to the relative importance of these two stimuli in completing the task. In the research presented in this paper, we used the same system, but reduced the availability of a …

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Development Of A Particle Flow Test For Rotational Molding, Russell B. Whatcott Jun 2008

Development Of A Particle Flow Test For Rotational Molding, Russell B. Whatcott

Theses and Dissertations

One of the current testing method (the Dry Flow test) to qualify resin for use in production in the rotomolding process has been shown to have many flaws in both equipment and procedure. Research was done here to investigate a possible alternative that could eliminate some of these testing deficiencies. By reducing equipment and operator errors, the testing of materials becomes more valuable of an exercise. The Angular Flow test developed in this research can increase repeatability. By coming to understand the rotational molding process better, an evaluation that can give more valid information was devised.

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Coordinated Design Of Power System Stabilizers And Static Var Compensators In A Multimachine Power System Using Genetic Algorithms, Omar H. Abdalla, Wedad M. Refaey, Mohamed K. Saad, Gamal M. Sarhan Apr 2008

Coordinated Design Of Power System Stabilizers And Static Var Compensators In A Multimachine Power System Using Genetic Algorithms, Omar H. Abdalla, Wedad M. Refaey, Mohamed K. Saad, Gamal M. Sarhan

Omar H. Abdalla

This paper presents a procedure to coordinated design of PSSs and SVCs in a multimachine power system. The aims of the proposed method are to find the best location and the optimal parameters of these compensators in order to improve the steady state and transient performances and also to increase the system damping over a wide range of operating conditions. The objective function of the GA allows the selection of the PSSs and SVCs to shift critical closed loop eigenvalues to the left-hand side in the complex s-plane. The multimachine power system considered in this study consists of nine buses, …

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Real-Time Implementation Of Vision Algorithm For Control, Stabilization, And Target Tracking For A Hovering Micro-Uav, Beau J. Tippetts Apr 2008

Real-Time Implementation Of Vision Algorithm For Control, Stabilization, And Target Tracking For A Hovering Micro-Uav, Beau J. Tippetts

Theses and Dissertations

A lightweight, powerful, yet efficient quad-rotor platform was designed and constructed to obtain experimental results of completely autonomous control of a hovering micro-UAV using a complete on-board vision system. The on-board vision and control system is composed of a Helios FPGA board, an Autonomous Vehicle Toolkit daughterboard, and a Kestrel Autopilot. The resulting platform is referred to as the Helio-copter. An efficient algorithm to detect, correlate, and track features in a scene and estimate attitude information was implemented with a combination of hardware and software on the FPGA, and real-time performance was obtained. The algorithms implemented include a Harris feature …

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Bi-Directional Dcm Dc-To-Dc Converter For Hybrid Electric Vehicles, Michael Pepper Jan 2008

Bi-Directional Dcm Dc-To-Dc Converter For Hybrid Electric Vehicles, Michael Pepper

Electronic Theses and Dissertations

With the recent revival of the hybrid vehicle much advancement in power management has been made. The most popular hybrid vehicle, the hybrid electric vehicle, has many topologies developed to realize this hybrid vehicle. From these topologies, as sub set was created to define a particular group of vehicles where the converter discussed in this thesis has the most advantage. This sub set is defined by two electric sources of power coupled together at a common bus. This set up presents many unique operating conditions which can be handled seamlessly by the DC-to-DC converter when designed properly. The DC-to-DC converter …

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Motion Segmentation For Humanoid Control Planning, Matthew Field, David A. Stirling, Fazel Naghdy, Zengxi Pan Jan 2008

Motion Segmentation For Humanoid Control Planning, Matthew Field, David A. Stirling, Fazel Naghdy, Zengxi Pan

Faculty of Engineering - Papers (Archive)

The discovery of major management behaviours from human motion data and uncovering their underlying components is investigated. A range of methods for segmenting major shifts in multidimensional time series are compared in inducing plausible behaviours from motion data. These behaviours are considered as supersets of motion primitives that define a repertoire of manoeuvres available to the human. The resulting multilayered symbolic model is used as a framework for humanoid imitation and control. It is hoped that with appropriate matching and scaling of degrees of freedom, models can be tested by extracting a trajectory for a simulation of the Nao soccer …

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Online Optimal Control Of The Central Chilling System In A Super High-Rise Commercial Building, Shengwei Wang, Zhenjun Ma Jan 2008

Online Optimal Control Of The Central Chilling System In A Super High-Rise Commercial Building, Shengwei Wang, Zhenjun Ma

Faculty of Engineering - Papers (Archive)

This paper presents the online optimal control strategies of the central chilling system in a super high-rise building in Hong Kong. The work presented aims at developing a package of optimal control strategies and evaluating their energy saving potentials and finally implementing these strategies in the building to enhance its energy efficiency. Based on testing the effects of interactions within the cooling water system and chilled water system on the system operation performance, the optimal control strategies for the cooling water system and variable speed pumps with different installations in the secondary chilled water system are developed. These strategies are …

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A Novel Dynamic Absorber Using Enhanced Magnetorheological Elastomers For Powertrain Vibration Control, Nong Zhang, Nga Hoang, Haiping Du Jan 2008

A Novel Dynamic Absorber Using Enhanced Magnetorheological Elastomers For Powertrain Vibration Control, Nong Zhang, Nga Hoang, Haiping Du

Faculty of Engineering and Information Sciences - Papers: Part A

This paper presents a novel Adaptive Tuned Vibration Absorber (ATVA) using the enhanced magnetorheological elastomers (MREs) for powertrain vibration reduction. The MRE material used in this application includes micro-sized iron particles enhanced by adding nano-sized magnetic powders. With the enhancement, MRE's elastic modulus significantly increases due to the MR effect. In the new ATVA, the MRE plays a role as a torsional spring whose stiffness coefficient can be varied with an external magnetic field. Additionally, this ATVA could operate in shear-squeeze mode rather than shear mode. Thus, the frequency range is much wider than that of general MREs. Such property …

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Robust Adaptive Control Of Conjugated Polymer Actuators, Yang Fang, Xiaobo Tan, Gursel Alici Jan 2008

Robust Adaptive Control Of Conjugated Polymer Actuators, Yang Fang, Xiaobo Tan, Gursel Alici

Faculty of Engineering - Papers (Archive)

Conjugated polymers are promising actuation materials for bio- and micromanipulation systems, biomimetic robots, and biomedical devices. Sophisticated electrochemomechanical dynamics in these materials, however, poses significant challenges in ensuring their consistent, robust performance in applications. In this paper, an effective adaptive control strategy is proposed for conjugated polymer actuators. A self-tuning regulator is designed based on a simple actuator model, which is obtained through reduction of an infinite-dimensional physical model and captures the essential actuation dynamics. The control scheme is made robust against unmodeled dynamics and measurement noises with parameter projection, which forces the parameter estimates to stay within physically meaningful …

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Electric-Powered Wheelchairs As An Assistive Technology, Aidan O'Dwyer, Malabika Basu, Eugene Coyle Jan 2008

Electric-Powered Wheelchairs As An Assistive Technology, Aidan O'Dwyer, Malabika Basu, Eugene Coyle

Conference papers

This paper briefly outlines recent work done, particularly in control systems, for electric powered wheelchairs. These mobility aids, first developed in the 1950’s [1], were improved with the incorporation of microprocessors. The requirement for mobility aids in general is rising; for example, it is reckoned that 1.5% of the U.K. population require such aids. As an assistive technology, electric powered wheelchairs have many benefits. Nevertheless, a reliable and robust such wheelchair has still to evolve.

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Congestion Avoidance And Fairness In Wireless Sensor Networks, Mohammad Ahmad Jan 2007

Congestion Avoidance And Fairness In Wireless Sensor Networks, Mohammad Ahmad

Electronic Theses and Dissertations

Sensor network congestion avoidance and control primarily aims to reduce packet drops while maintaining fair bandwidth allocation to existing network flows. The design of a congestion control algorithm suited for all types of applications in sensor networks is a challenging task due to the application-specific nature of these networks. With numerous sensors transmitting data simultaneously to one or more base stations (also called sinks), sensor nodes located near the base station will most likely experience congestion and packet loss. In this thesis, we propose a novel distributed congestion avoidance algorithm which calculates the ratio of the number of downstream and …

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