Applied Control

Principal Investigator Professor Stephen Duncan

Group Members

• Professor Stephen Duncan - Academic
• Dr Matthew Arthington - Post-doctoral Research Assistant, 2013 -
• Ross Drummond - DPhil student, 2013 -
• Adrien Bizeray - DPhil student, 2012 -
• Shi Zhao - DPhil student, 2011 -
• Sandira Gayadeen - DPhil student, 2010 -
• Previous Members

Projects

Fast Orbit Feedback Stabilisation System for a Synchrotron

Synchrotrons can produce very intense beams of X-rays and ultra violet light for a range of applications including protein crystallography, materials characterisation and high resolution imaging. The Diamond Light Source is the UK's national synchrotron facility, which produces a 3GeV electron beam in a ring of circumference 560m. A key component of the process is the fast beam stabilisation system that regulates the horizontal and vertical position of the beam in the presence of disturbances in the range 1 to 100Hz using 178 sensors and actuators positioned around the ring. Using concepts from the design of cross-directional control systems for web industries, a control system has been designed and successfully implemented on the synchrotron. Current research is focussing on implementing the control system on the booster synchrotron.

Participants: Sandira Gayadeen, Ashley Napier, Stephen Duncan, Michael Abbott, Isa Uzun, Günther Rehm, Mark Heron

Partners: Diamond Light Source

Duration: 2007 to date

 

Modelling and Control of Supercapacitors

Supercapacitors and ultracapacitors are a promising technology for electrical energy storage that could be used to smooth variations on electric power grids in cases where there is the potential for variability of supply coupled with fluctuations in demand. In order to manage and optimise the use of supercapacitors as a source of energy storage, it is important to be able to estimate their state of charge from measurements that can be taken from the grid (typically voltages and currents). This project is developing low order models of the electrochemistry within ultracapacitors, which can be used as the basis of observers for estimating the state of charge of these devices.

Participants: Ross Drummond, Stephen Duncan, David Howey

Duration: 2013 to date

 

Closed-loop Control of Flexible High Value Metal Component Manufacture

Manufacturing involves only three types of processes - adding, changing or removing material. 'Metal Bashing' - changing the shape of metal components without removal or additions - is easily over-looked but continues to be central to UK manufacturing: jet engines, medical scanners, cars, high-rise offices and contemporary industrial equipment all depend on metal forming, both to define component geometries and to create the properties such as strength and toughness which determine product performance. Metal forming processes are central to the production of a third of all manufactured exports from the UK which are in total worth over £75bn. However, the tools required for forming metal components are custom-made for each application at great cost, so metal forming is often expensive unless used in mass production, yet the drivers for development of future high-value UK manufacturing require increased flexibility and smaller batch sizes without sacrificing either the accuracy or properties of metal parts.

In the past twenty years, several research labs around the world have responded to this challenge and explored the design and development of novel flexible metal forming equipment. However these processes have largely failed to move from the lab into industrial use, due to a lack of precision and a failure to guarantee product microstructure and properties. Recent developments in sensors, actuators, control theory and mathematical modelling suggest that both problems could potentially be overcome by use of closed-loop control.

The project brings together four disciplines, previously un-connected in the area of flexible forming, to develop the key knowledge underpinning future development of commercially valuable flexible metal forming equipment: mechanical design of novel equipment; control-engineering; materials science of metal forming; fast mathematical process modelling. At the heart of the project is the ambition to link design, metallurgy and modelling to control engineering, in order to develop and apply flexible forming, and to demonstrate it in practice in four well focused case-studies.

Participants: Matthew Arthington, Stephen Duncan, Jianglin Huang, Roger Reed, Vahid Jenkouk, Evros Loukadies, Julian Allwood, Chris Cawthorne, Ed Brambley

Partners: Department of Material Science, University of Oxford; Department of Engineering and DAMTP, University of Cambridge; Siemens VAI; Firth Rixon; Jaguar Land Rover

Duration: 2013 to date

 

Battery Managment Systems

Batteries are increasingly being used for applications such as hybrid electric vehicles and as sources of energy storage on electric power grids. In order to be used effectively, the battery has to be combined with a battery management system that monitors and regulates the state of charge within the battery. This project, which is carried out in conjunction with the Energy and Power Group at Oxford, is developing systems for monitoring the state of charge within Lithium-ion batteries by using low order models of the diffusion of charge and ions as the basis of observers.

Participants: Adrien Bizeray, David Howey, Stephen Duncan

Partners: Samsung

Duration: 2013 to date

 

Passive Flow Control

This project investigates a method of reducing drag over airfoils by combining ideas from control theory and aerodynamics. An approach that has been considered in the past that results in a significant reduction in drag, is the introduction of riblet structures on the aerodynamic body. Riblets are structures that run parallel to one another, that are positioned longitudinally to the flow and usually have a triangular cross-section in the transverse direction. Previous research has shown that these structures can be optimized to produce a reduction in the drag coefficient of up to 10%. The use of riblets is a passive method of controling the flow, but by ideas from feedback control theory can be used to analyse and optimise the shape and dimensions of the riblets.

Participants: Shi Zhao, Stephen Duncan

Duration: 2011 to date

 

Cross-directional Control Systems for Web Processes

Cross-directional (CD) control systems have been common in the web processing industries (such as paper making, metal rolling and plastic film extrusion) since the 1980’s. In the past two decades, considerable research has taken place in the field of CD control and a range of alternative strategies have been proposed. This study will benchmark an existing CD controller installed on a plastic film extrusion line against state of the art controllers, in order to identify opportunities for improved profile control and extend modern control design methods to multi-array CD control systems.

Participants: Andrew Taylor, Stephen Duncan, William Heath

Partners: DuPont Teijin Films (UK) Limited; Department of Electrical Engineering and Electronics, University of Manchester.

Duration: 2006-2013

 

Sustainable Policies for Greenhouse Gas Emissions

This project uses concepts from modern robust control theory to develop algorithms for determining the optimal policy that both achieves sustainable levels of emissions of CO2 (and other greenhouse gases) and minimises the impact on the economy, but also explicitly addresses the high levels of uncertainty associated with predictions of future emissions. The aim of the optimal policy is to adjust factors such as the mix of energy generation methods and policies for reducing emissions from housing, industry and transport, in order to achieve a rate of emissions that will allow the UK to achieve its emissions targets while maximising economic growth as measured by discounted GDP. A key difficulty in determining the optimal policy is handling the uncertainty associated with the effect that the policy changes will have on the rate at which is CO2 emitted. Concepts from robust control theory are used to develop tools for incorporating uncertainty directly into the design of the optimal emissions policy; the tools can then be applied to other existing models. Including uncertainty within the design quantifies the risk associated with the emissions policy, which allows policy makers and emitters of CO2 to incorporate risk within their strategic plans.

Participants: Bing Chu, Stephen Duncan, Antonis Papachristodoulou, Cameron Hepburn, Simon Roberts

Partners: London School of Economics; Arup

Duration: 2010-2013

 

Control of Incremental Sheet Forming

Incremental sheet forming is a novel small-scale, production process, which is relevant for prototyping, low volume production and customisation and which potentially may lead to environmental improvements, primarily through locating production nearer to customers. The process is an alternative to the standard sheet pressing processing currently used in many manufacturing industries, in which a pair of specially-made dies press a flat sheet into a required geometry. This is efficient, but it is expensive for low volume manufacture, due to the cost of making the dies. Incremental sheet forming uses a small indentor, which is dragged around the sheet, creating a small 'kinked' track. As the tool continues to track over the sheet, a deformed shape is built up as the sheet undergoes plastic deformation. Any shape that can be made by pressing, can also be made by incremental forming, the difference being that incremental forming does not require any special tooling.

The project is carried out in conjunction with the Department of Engineering at the University of Cambridge, where the first dedicated rig outside Japan has been built to explore this process. The control challenge is that the actuator is a moving tool, whose effect on the sheet depends on its location, and on the past deformation undergone by the sheet. The project uses a model of the plastic deformation of the sheet to determine the optimal path for the indentor and then develop and implement a feedback control system using measurements from a vision system.

Participants: Hao Wang, Ankor Raithatha, Stephen Duncan, Kathryn Jackson, Omer Music, Julian Allwood

Partners: Department of Engineering, University of Cambridge

Duration: 2005-2011

 

Control of Fluidised-bed Dryers using Process Tomography

The aim of the project is to develop new technologies for product quality control by combining inferential sensing, online process modelling, tomographic imaging of physical properties and distributed parameter control. To demonstrate the benefits of this strategy, a real-time closed-loop control system will be developed to regulate spatial distribution of gas-solids and moisture content distribution in a fluidised bed dryer. A typical application of a fluidised bed dryer is in the drying of tablets for the pharmaceutical industry. Air is blown from the bottom through a vessel containing the tablets, which are dried as they “float” in the air flow and a typical quality specification is to ensure that moisture content of the all tablets in the dryer is uniform. At present, fluidised bed dryers are "black boxes", i.e. it is difficult to know what is going on inside, but industrial process tomography allows the variations in the moisture of the tablets within the dryer to be measured. In the past, tomography has primarily been used solely for process monitoring, but this project offers the first opportunity of using tomography for product quality control. The proposed control scheme will be based on online modelling of desired gas-solids distribution and moisture content distribution, from which desired capacitance and loss-conductance profiles can be derived. Both capacitance and loss conductance measurements from tomographic sensors will be used as feedback signals for controlling the process in terms of the difference between the desired profile within the dryer and the measured profile. The system will control both the gas-solids distribution and the moisture content distribution in the dryer.

Participants: Javier Villegas, Mingzhong Li, Stephen Duncan, Haigang Wang, Rambadi Ragavan, Wuqiang Yang, Peter Senior

Partners: Department of Electrical Engineering and Electronics and Department of Chemical Engineering, University of Manchester; Astra Zeneca; Sensatech

Duration: 2005-2008

 

Past Projects