Local Motion Planning for Unmanned Air Vehicle in Complex Obstacle Rich Environments

Andrew Berry

QinetiQ, Unmanned Air Systems & Autonomous Vehicles

ABSTRACT

This seminar will provide an overview of research conducted under an Engineering Doctorate programme supervised by Ian Postlethwaite & Dawei Gu. This programme of research is concerned primarily with local motion planning tools that help enable unmanned vehicles to operated within complex obstacle rich environments. The specific application of interest is the military use of micro air vehicle (MAVs) in direct support of ground troops operating in urban environments. The approach taken to this problem is a systems engineering one, where significant effort is directed towards defining the context within which technical work takes place. The aim of this approach was to ensure that the technical work was conducted with a view to required military needs and realistic operational environments. The specific technical focus is 'situation aware' trajectory tracking, i.e. allowing an unmanned vehicle to track a pre-defined global trajectory with reference to the surrounding obstacle space. This problem is posed within a receding horizon framework, where feasible local motion trajectories are continually optimised considering available vehicle performance, local obstacle space & the desired global trajectory.

Monday, 12 October 2009, 12:00 am, MacLellan Room

Modelling, observation and control of biotechnological processes

Isabelle Queinnec

LAAS-CNRS, Université de Toulouse, France

ABSTRACT

The objective of this talk is to make a link between some classical tools in control theory (state-space models, stability analysis, identification, observation and control...) and biochemical processes (from biotechnology to waste-water treatment processes). Main classical ideas relative to modelling of biochemical processes are given in the first part of the talk, with several examples to illustrate the key principles. The second part is then related to some structural analysis of the models, with particular focus on stability, controllability and observability properties. This explains why control is not so much used in biochemical industry. Then, the third part of the talk is devoted to the presentation of various observation strategies (with particular emphasis to the case with unknown input) applied in the context of a waste-water treatment unit.

Friday, 09 October 2009, 12:00 am, MacLellan Room

Stability analysis and state feedback control design of discrete-time systems with a backlash

Sophie Tarbouriech

LAAS-CNRS, Université de Toulouse, France

ABSTRACT

This talk considers the class of discrete-time nonlinear systems resulting from the connection of a linear system with a backlash operator. By conveniently exploiting the properties of the backlash, a class of candidate Lyapunov functions with quadratic terms and Lur'e type terms, derived from generalized sector conditions, is introduced. Using this class of Lyapunov functions, the stability of the time-shifted system is investigated. Additionally, the set of equilibrium points, which can estimated, may be not reduced to the origin, since the backlash operator contains a dead-zone. Sufficient convex conditions, formulated in terms of semi-definite programming, are provided for the stability analysis and for the design of a linear stabilizing state-feedback controller. Numerical simulations illustrate the results and some computational issues.

Monday, 28 September 2009, 12:00, MacLellan Room

Methods for Reverse-Engineering Gene Regulatory Networks

Prof. Carlo Cosentino

School of Computer and Biomedical Engineering
Department of Experimental and Clinical Medicine
Università degli Studi Magna Græcia di Catanzaro, Italy

ABSTRACT

Research on complex networks has been a subject of rigorous theoretical research in the mathematics and physics research communities in the past decade. The many discoveries that human interactions, man-made and natural networks share a power-law degree distribution and small-world property have clearly indicated a high level of relevance of the study of complex networks with real-world applications. However, progress in applying the theoretical results to solving practical problems is still slow. In this talk some recent results in applying complex networks research in real-world problems will be reviewed. The emphasis is on how complex networks would provide a new perspective on the way problems can be formulated, leading to possible new solution approaches. Examples in engineering, disease transmission, language, music and finance will be given. The talk will be presented for very general audience.

BIO

Chi K. (Michael) Tse (M'90—SM'97—F'06) received the B.Eng degree with first class honors and the Ph.D. degree from the University of Melbourne, Australia, in 1987 and 1991, respectively. In 2006, he was elected IEEE Fellow. He is presently Chair Professor of Electronic Engineering and Head of Department of Electronic and Information Engineering at the Hong Kong Polytechnic University, Hong Kong. His research interests include complex network applications, power electronics and chaos-based communications. He is the author of the books Linear Circuit Analysis (London: Addison-Wesley, 1998) and Complex Behavior of Switching Power Converters (Boca Raton: CRC Press, 2003), co-author of Chaos-Based Digital Communication Systems (Heidelberg: Springer-Verlag, 2003), Digital Communications with Chaos (London: Elsevier, 2006), and Reconstruction of Chaotic Signals with Applications to Chaos-Based Communications (Beijing: TUP, 2007). Dr. Tse received the L.R. East Prize from the Institution of Engineers, Australia, in 1987, the Best Paper Award from IEEE Transactions on Power Electronics in 2001, Dynamics Days Europe Presentation Prize in 2002, and the Best Paper Award from International Journal of Circuit Theory and Applications in 2003. While with the Hong Kong Polytechnic University, he received the President's Award for Achievements in Research in 1997 and 2000, the Faculty Best Researcher Award in 2000, the Faculty Research Grant Achievement Award in 2004, and a few other teaching awards. In 2005, he was named an IEEE Distinguished Lecturer. In 2006 he was elected an IEEE Fellow. In 2007, he received the Distinguished International Research Fellowship from the University of Calgary, Canada. Dr. Tse is the Editor-in-Chief of IEEE CAS Newsletter, Associate Editor of IEEE CAS Magazine, IEEE Transactions on Circuits and Systems, Part I — Fundamental Theory and Applications, and IEEE Transactions on Power Electronics, International Journal of Systems Science and International Journal of Circuit Theory and Applications. He also served as Guest Editor for a number of journals. He currently also serves as an Associate Editor for the International Journal of Systems Science.

Wednesday, 1 July 2009, 3:00pm, MacLellan Room

Automated Therapy Systems Using Nonlinear and Adaptive Control Systems

Dr. Radhakant Padhi

Dept. of Aerospace Engineering, Indian Institute of Science, Bangalore  

Biography

Dr. Radhakant Padhi is currently working as an Assistant Professor in the Department of Aerospace engineering, Indian Institute of Science - Bangalore. He received his Bachelor of Engineering in Mechanical Engineering from University College of Engineering-Burla, Orissa in 1994, followed by Master of Engineering in Aerospace Engineering from Indian Institute of Science, Bangalore in 1996. He earned his Ph.D. in Aerospace Engineering from University of Missouri - Rolla, USA in 2001. After earning his Ph.D., he was a postdoctoral fellow in the same university until Dec 2003. Dr. Padhi has also served as a scientist at RCI (DRDO), Hyderabad during 1996-1997. He is a member of Institute of Electrical and Electronics Engineers (IEEE), American Institute of Aeronautics and Astronautics (AIAA), Aeronautical Society of India and Systems Society of India. He is a member of technical committee on aerospace in International Federation of Automatic Control (IFAC). He is also an Editor of Journal of Systems Science & Engineering. Dr. Padhi's research interests are in the broad area of systems theory and applications. Specifically, he is interested in optimization and optimal control, distributed parameter systems, neural networks, control and guidance of aerospace vehicles and application of control theory in biomedical systems. He has numerous publications in international journals and conferences. He has received many awards and honours; the most recent being the System Society of India Young Scientist Award in 2008, Indian National Academy of Engineering (INAE) Young Engineer Award in 2007 and the best application paper award in 29th National Systems Conference in 2005. He has also received certificate of recognition for valued scholastic contributions from University of Missouri-Rolla and best student paper award in 2001 IEEE joint Conference on Control Applications and International Symposium on Intelligent Control.

Friday, 26 June 2009, 3:00pm, MacLellan Room

Nonlinear Partial Integrated Guidance and Control of Missiles for Missile Defense

Dr. Radhakant Padhi

Dept. of Aerospace Engineering, Indian Institute of Science, Bangalore   

ABSTRACT

To address the concern of classical guidance and control designs (where guidance and control loops are designed separately in an "outer loop - inner loop" structure), integrated guidance and control (IGC) ideas have been proposed in the recent literature. An important limitation of the existing IGC algorithms, however, is that they do not explicitly exploit the inherent time scale separation that exist in aerospace vehicles between rotational and translational motions, and hence, can be ineffective unless the engagement geometry is close to the collision triangle. To address this, a time scale separated partial integrated guidance and control (PIGC) structure will be proposed in this seminar. In this two-loop design, the commanded pitch and yaw rates are directly generated from an outer loop optimal control formulation, which is solved in a computationally efficient manner using the recently-developed model predictive static programming (MPSP) technique. The necessary roll-rate command is generated from a roll-stabilization loop. The inner loop then tracks the outer loop commands using the Dynamic inversion philosophy. However, unlike classical guidance and control designs, in both the loops the Six-DOF interceptor model is used directly. This intelligent manipulation preserves the inherent time scale separation property between the translational and rotational dynamics, and hence overcomes the deficiency of current IGC designs, while preserving the benefits of the IGC philosophy. The new approach has been applied in the terminal phase of an endo-atmospheric interceptor for engaging incoming high speed ballistic missile targets. Six-DOF simulation results will be presented accounting for a 3-D engagement geometry to demonstrate the usefulness of this method. It offers two important advantages: (i) it leads to very small (near-zero) miss distance, resulting in a "hit-to-kill" scenario and (ii) it also leads to lesser and smoother body-rate demands, relaxing the demand on actuators as well as enlarging the 'capture region' (which relaxes the demand on mid-course guidance). Next, to address the problem of modeling inaccuracy that is inherent in aerospace vehicles, a neuro-adaptive design is augmented to dynamic inversion technique in the inner loop. This adaptive body rate tracking loop augmented with the nonlinear sub-optimal feedback guidance loop results in substantial enhancement of interception performance in presence of realistic (i.e. fairly large) modeling uncertainties of the interceptor.

Thursday, 25 June 2009, 2:00pm, KE526

Convergency and frequency response functions in nonlinear systems

Professor Henk Nijmeijer

Eindhoven University of Technology

ABSTRACT

The purpose of the talk is twofold.  First, it is argued that the notion of convergency, that stems from  Russian literature in the 50-60s of the last century, is extremely useful in the context of various nonlinear control synthesis problems.  Convergency, which is closely related to notions like input to state  stability or incremental stability, requires that for any bounded input,  the system possesses a unique limiting solution. During the talk,  convergency wil be introduced, and its use in the regulator problem will  be demonstrated. The second contribution of the talk focusses on frequency response  functions for the class of convergent nonlinear control systems. For  this particular class, which encompasses standard linear systems, one  can thus discuss the performance of the system using 'linear' Bode  magnitude plots. An example featuring the approach will finally be treated. 

Wednesday, 20 May 2009, 2:00pm, MacLellan Room

Power law modelling of internet topology

Dr. Shi Zhou

Department of Computer Science, University College London

ABSTRACT

In recent years there have been tremendous efforts to mea sure, characterise and model the internet topology. We discuss why the power law degree distribution is not an artifact but an integral property of the internet. On the other hand we argue that while it is one of the properties that fundamentally characterise the global internet structure, other properties should also be considered to obtain a full description of the network. We review the power law modelling of the internet topology and provide a critical look at the contribution of such research to the Internet engineering.

BIO

Shi Zhou is a Lecturer with Department of Computer Science, University College London. He is a holder of the Royal Academy of Engineering/EPSRC Research Fellowship. His research interests are in the characterisation and modelling of large-scale complex networks, with an emphasis on information and communications networks such as the Internet and the World Wide Web.

Wednesday, 13 May 2009, 2:00pm, LT1

Note: usual time different venue.

Computational Study on Deployment and Stability of Inflatable Membrane Systems

Dr. Yixiang Xu

University of Strathclyde

ABSTRACT

The use of inflatable system has been the desire for longer duration stratospheric flights at constant float altitudes for heavy payloads. It has been the focus of the development of the National Aeronautics and Space Administration’s (NASA) Ultra Long Duration Balloon (ULDB) program to develop a low cost, long duration balloon system to support global scientific observations above most of the earth's atmosphere for durations approaching 100 days. A problem of this system is that these balloons are prone to becoming unstable and unable to pressurize into the desired axis-symmetric equilibrium configuration, settling into a distorted state instead. This seminar presents a computational study of the stability and post-buckling behaviour of a 10 m diameter, 145 lobe pumpkin balloon system, with lobes of approximately uniform radius. The ABAQUS commercial finite-element package is used. First, a geometrically non-linear analysis is carried out to inflate the balloon to a pressure high enough to make the balloon fully wrinkle free. This is followed by an eigenvalue buckling analysis to predict the critical pressures corresponding to different buckling modes. Then, new models are set up with an initial imperfection mode based on the both critical and combined eigenmodes. Finally, a non-linear post-buckling analysis is carried out to simulate the response of the system beyond the critical load.

BIO

Dr. Yixiang Xu is a Lecturer in the Department of Civil Engineering at the University of Strathclyde, Glasgow. He is working in the Infrastructure Group at the David Livingstone Centre for Sustainability (DLCS) to provide innovative solution in the environment, infrastructure and transportation. He obtained his B.Eng. degree at the Department of Mechanical Engineering and Automation, Shanghai Jiao Tong University in 2002. Subsequently, he carried out research in shell and inflatable membrane structures in Deployable Structures Lab (DSL) at Cambridge University and finished his Ph.D. in 2007. Before he took his current appointment, he was a specialist engineering consultant at the ScottWilson Ltd.

Friday, 24 April 2009, 2:00pm, LT1

State Feedback Design for Input-Saturating Quadratic Systems

Giorgio Valmorbida

LAAS, Toulouse

ABSTRACT

Results allowing the design of stabilizing state feedback control laws for nonlinear quadratic systems subject to input saturation will be presented. Based on quadratic Lyapunov function, a modified sector condition and using a particular representation for the quadratic terms, synthesis conditions in a quasi LMI form can be stated in a regional (local) context. An LMI-based optimization problem is then derived for computing the state feedback gains maximizing the estimates of the stability region of the closed-loop system.

Wednesday, 25 March 2009, 2:00pm, MacLellan Room

Dynamic models for a long body waves propagating in a sheared pre-stressed incompressible elastic layer

Dr Svetlana Amirova

Systems Biology Lab, Department of Engineering, Univ. of Leicester

ABSTRACT

Nowadays rubbers like materials are popular in modern technology including various engineering and biomedical applications. This interest is partially motivated by their important ability to undergo finite primary deformations, leading to a pre-stressed state. In the presentation we outline our approach to elucidate the dynamic response of incompressible elastic layer subject to primary simple shear deformation considering different boundary conditions. The first goal is to provide an asymptotic analysis of associated dispersion relations. The second aim is to construct simplified asymptotically consistent dynamic models.

Wednesday, 25 February 2009, 2:00pm, MacLellan Room

Anti-windup and the preservation of robustness against structured norm-bounded uncertainty

Dr Rafael M. Morales

Control Lab, University of Leicester

ABSTRACT

The presentation will discuss robustness preserving anti-windup with structured norm-bounded uncertainty. A sufficient condition for the existence of such anti-windup is given, together with an expression for its construction. Existing results in the literature for unstructured uncertainty appear as a special case. The so-called IMC (internal model control) anti-windup does not necessarily preserve robustness for the general case. Also, the talk will present a graphical test for the robustness of SISO IMC anti-windup against linear-time-varying norm-bounded uncertainty.

Wednesday, 26 November 2008, 2:00pm, McLellan Room

Model Predictive Control for tracking of constrained linear systems

Prof Daniel Limon

University of Seville

ABSTRACT

Most of the industrial processes operates around a target point in which its efficiency is maximized. Nevertheless, there often exist events or scenarios in which the operating point changes. Appropriate control laws must be designed to accomplish with these possible changes. On the other hand, the systems are typically subject to constraints and limitations to be fulfilled along the evolution of the plant. These can stem from hard limits in process variables, saturation on the actuators, operating ranges, etc. Model predictive control (MPC) is one of the few control techniques able to consider constraints, on both state and inputs of the system, in the design of the control law for linear, nonlinear or uncertain systems.

This problem is typically solved by means of a two-level structure. The selection of the target point is typically made according to different criteria: economics, production, environmental, etc. According to this given target, the optimal steady state is calculated on line by an upper level optimizer called Real-Time Optimizer (RTO). This provides the set-points to the lower level model predictive controllers which must steers the system to these set-points considering the performance of the transient as well as the constraints. For practical application of model predictive controllers, these must be able to handle with non-zero and changing set-points provided by a RTO. The finite control horizon and the constraint imposed on the terminal state can make that the set-points not reachable and the feasibility of the optimization problem is not ensured for all the time. This can be solved by re-calculating the control horizon and the terminal set for the new set-points, but this results to be non-practical.

The talk will present some novel results on the formulation of model predictive control laws for constrained linear systems under a changing operation point scenario. It will be shown how this problem can be solved by a single MPC integrating the RTO in the controller. The resulting control law ensures feasibility and convergence under any change on the target. Robust formulation of the controller for both state and ouput feedback cases will be also presented. Finally some real application of the presented controllers will demonstrate the benefits of the proposed solutions.

Tuesday, 22 July 2008, 2:00pm, MacLellan Room

NOTE: Usual venue but different day of the week.

Insight into Some activity on Guidance and control and design of Unmanned Mini Air Vehicle

Prof. M. Seetharama Bhat

Department of Aerospace Engineering, Indian Institute of Science, Bangalore

ABSTRACT

Part I: Design of Integrated Guidance and Control for Missiles Using Variable Structure control

This talk presents development of control law using discrete variable structure control in output feedback mode for integrated guidance and control with seeker dynamics during its terminal phase. Traditionally, separate design of two loops, slow outer guidance loop and faster inner flight control or autopilot loop entail the use of higher bandwidth actuators which also consume large power. Addition of seeker delay and radome slope error to such a system will further deteriorate performance and at same time reduce robustness of the controlled system. The integrated system design is expected to reduce the requirement on both actuator and seeker performance requirements. By explicitly including the dynamics of actuator and seeker, a better sub-optimal solution is intended to be obtained.

Part II: Development of Unmanned Air Vehicles at Aerospace Engineering, IISc

Micro Air Vehicle (MAV) is a low cost platform for development of technology and evaluation of advanced control algorithms. In order for MAVs to perform a wide range of functions with a large degree of autonomy, augmentation of basic stability and control is needed. Stability and control of MAV presents difficult challenges since they operate in unusual flight domains and are susceptible to large wind gusts. Additionally, due to the lack of complete knowledge of the aerodynamics properties of a small scaled vehicle, the uncertainties are prominent in its mathematical representations. Miniature sensors used in MAV sacrifice accuracy for reduced size and weight. To handle problems involving uncertain dynamics, low efficiency actuators and sensors, multivariable robust control design techniques are needed.   This talk presents the development of different platforms or UAVs at Aerospace engineering, IISc, Bangalore and glimpse into control design aspects.

Wednesday, 25 June 2008, 2:00pm, MacLellan Room

Feedback Control and the Arrow of Time

Prof Malcolm Smith

Department of Engineering, University of Cambridge

ABSTRACT

The talk reports on recent joint work with Tryphon Georgiou on the central role that the time asymmetry of stability plays in feedback control. It is shown that this provides a new perspective on the use of doubly-infinite or semi-infinite time axes for signal spaces in control theory. The talk goes on to explain the implications of this time asymmetry in modeling uncertainty, regulation and robust control. We point out that modeling uncertainty and the ease of control depend critically on the direction of time. We also discuss the relationship of this control-based time-arrow with the well known arrows of time in physics.

Wednesday, 18 June 2008, 2:00pm, MacLellan Room

Sliding mode control of Large Size Nuclear Reactor

Prof. Bijnan  Bandyopadhyay

Indian Institute of Technology Bombay

ABSTRACT

In this talk modeling of large size pressurized Heavy Water Reactor (PHWR) will be discussed. An important phenomena known as spatial oscillation will be explained. For the control of spatial oscillation, why a detailed model of reactor is needed will be discussed. Recently developed multirate output feedback based sliding mode control will be discussed and the application of this technique to this reactor for the control of zonal power will be discussed. Several representative simulation results will be explained.

 Monday, 16 June 2008

Joint Bioengineering and  Control seminars

2:00pm, LT1

From Topology to Dynamics in Complex Signalling Networks

Prof. Kwang-Hyun Cho

Laboratory for Systems Biology and Bio-Inspired Engineering Department of Bio and Brain Engineering Korea Advanced Institute of Science and Technology (KAIST)

ABSTRACT

The life sciences have recently witnessed a shift of paradigm from traditional characterization of individual molecules towards an understanding of interactive pathways and networks of molecules. Different signal transduction pathways often share information through cross-talk and such cross-talk can form feedback loops that play important roles in the regulation of cell growth, proliferation, and differentiation in response to external stimuli. Intriguingly, these feedback loops are frequently found as a coupled structure in complex cellular circuits. We have investigated the coupled feedback loops in various cellular circuits and determined the dynamical role of each coupled structure. In particular, we have found that coupled positive feedbacks enhance signal amplification and bistable characteristics; coupled negative feedbacks promote homeostasis; and positive and negative feedbacks together enable a reliable decision making process by properly modulating signal responses and noises. We have further investigated the role of those coupled feedback loops in large-scale networks and evaluated their critical implications in robustness, fragility, and essentiality. In this presentation, I will argue that studying the complex dynamics of multiple feedback loops is a key to understanding the regulatory mechanisms in signal transduction pathways.

BIO

Kwang-Hyun Cho received the B.S., M.S., and Ph.D. degrees in electrical engineering from the Korea Advanced Institute of Science and Technology (KAIST) in 1993, 1995, and 1998, respectively. He is currently an Associate Professor in the Department of Bio and Brain Engineering at the Korea Advanced Institute of Science and Technology (KAIST), also holds a joint position at the KAIST Institute for the BioCentury, and is a director of the Laboratory for Systems Biology and Bio-Inspired Engineering. He has been guest editor of SIMULATION: Transactions of the Society for Modeling and Simulation for the special issue of systems biology (vol. 79, no. 12, 2003) and IEEE Control Systems Magazine for the special issue of systems biology (vol. 24, no. 4, 2004). He co-founded Systems Biology as an Editor-in-Chief which was the world's first international journal in systems biology, launched by IEE (changed to IET in 2007) in London from 2004. He is currently an Editorial Board Member of Systems and Synthetic Biology (Springer, Netherlands, from 2006), BMC Systems Biology (BMC, London, U.K., from 2007), and Gene Regulation and Systems Biology (Libertas Academica, New Zealand, from 2007), and an Editorial Advisory Board Member of Molecular BioSystems (The Royal Society of Chemistry, U.K.). He is also an Associate Editor of BMC Systems Biology and BMC Research Notes (BMC, London, U.K., from 2008). He is a Senior Member of the IEEE Engineering in Medicine and Biology Society (EMBS). His research interests cover the areas of systems science with bio-medical applications including systems biology and bio-inspired engineering based on molecular systems biology. The focus of his research has been on applications in biotechnology and bio-medical sciences, in particular, a system-level analysis of cellular signal transduction pathways, reverse engineering of biomelocular regulatory networks from time-series data, unraveling hidden cellular dynamics, and development of new kinds of control systems inspired from molecular biology.

3:00pm, LT1

Model Selection and Parameter Inference for Systems Biology

Prof. Michael Stumpf

Laboratory for Theoretical Systems Biology and Bioinformatics, Imperial College

ABSTRACT

For the vast majority of biological systems, even though we might have extensive data, we lack mechanistic detailed models. Even where we have such models,a host of different mathematical representations may exist without any a priori knowledge as to which is to be preferred. We therefore require inferential tools that, given some observed biological data and a set of suitable mathematical candidate models, allow us to choose which model best describes a biological system. Here we describe recent developments in approximate Bayesian computation (ABC) which achieve just that. Our approach can equally well be applied to deterministic and stochastic models, and offers insights into model inferability, parameter sensitivity and robustness features of biological systems.

BIO

Michael Stumpf studied physics at the Universities of Tübingen and Göttingen and before moving to Oxford to study for a DPhil in condensed matter theory. In 1999 he moved to the Department of Zoology in Oxford where he took up a Wellcome Trust Research Training Fellowship in Mathematical Biology to investigate a range of problems related to evolutionary, stochastic and dynamical processes in biology. In 2002 he moved to UCL before coming to Imperial College in 2003. The work in his research group is primarily concerned with modelling and analyzing stochastic dynamical processes and networks in systems and evolutionary biology.

Wednesday, 11 June 2008, 2:00pm, MacLellan Room

The tumor growth inhibition model: an example of the role of modelling in the pharmaceutical field

Dr Monica Simeoni, GlaxoSmithKline

BIO

Monica Simeoni received a Laurea degree in electronic engineering in 1996 from the University of Padova, Padova, Italy and a Ph.D. degree in bioengineering in 2000 from the Politecnico di Milano, Milan, Italy. Since 2006 she has been a Senior Clinical Pharmacokinetist working for the Clinical Pharmacokinetics/Modeling and Simulation group at GlaxoSmithKline, Greenford (UK). Prior to that, she worked for five years for the Department of Computer Science and Systems Engineering at the University of Pavia on several collaborative projects with the former Pharmacia & Upjohn, Milan, now Nerviano Medical Sciences. She worked also at the Laboratory of Medical Technology of the Istituti Ortopedici Rizzoli, Bologna, Italy and for the Bioengineering group of the University of Padova. Her area of expertise is modelling of biological systems (oncology, glucose-insulin metabolism, neurology and antibodies), pharmacokinetics and pharmacodynamics in preclinical and clinical programmes. She is author of thirty-five publications, fifteen of which in peer-reviewed journals.

Wednesday, 21 May 2008, 2:00pm, MacLellan Room

Robust Stability and  Controllability  of  Stochastic Differential Delay Equations with Markovian Switching

Dr Chenggui Yuan, University of  Swansea

ABSTRACT

In this talk I will present the almost surely asymptotic stability for the nonlinear stochastic differential delay equations with Markovian switching. Some sufficient criteria on the controllability and robust stability are also established for linear stochastic differential delay equations with Markovian switching.

Wednesday, 02 April 2008, 3:00pm, LT2

NOTE: usual day of the week  but different time and venue, LT2 is the lecture room on the 2nd floor.

Joint Bioengineering and  Control seminar

Probabilistic Models of Human Sensorimotor Control

Prof Daniel Wolpert, University of Cambridge

ABSTRACT

The effortless ease with which humans move our arms, our eyes, even our lips when we speak masks the true complexity of the control processes involved. This is evident when we try to build machines to perform human control tasks. While computers can now beat grandmasters at chess, no computer can yet control a robot to manipulate a chess piece with the dexterity of a six-year-old child. A major factor that makes control hard is the uncertainty inherent in the world and in our own sensory and motor systems. I will review how the brain deals with this and demonstrate that a key feature of skilled human motor performance is the ability of the brain to perform optimally in the presence of uncertainty.

Wednesday, 27th February 2008, 2:00pm, MacLellan Room

Mechanical Steering Compensators for High-Performance Motorcycles

Prof David Limebeer

Control and Power Research Group, Imperial College

ABSTRACT

The talk will investigate the idea of using mechanical steering compensators to improve the dynamic behavior of high-performance motorcycles. These compensators are seen as possible replacements for the conventional steering damper, and comprise networks of springs, dampers and a less familiar component called the inerter. The inerter was recently introduced to allow the synthesis of arbitrary passive mechanical impedances, and finds a potential application in the present work. The design and synthesis of these compensation systems make use of the analogy between passive electrical and mechanical networks. This analogy is reviewed alongside the links between passivity, positive reality and network synthesis. Compensator design methods that are based on classical Bode-Nyquist frequency-response ideas are presented. Initial designs are subsequently optimized using a sequential quadratic programming algorithm. This optimization process ensures improved performance over the machine's entire operating regime. The investigation is developed from an analysis of specific mechanical networks to the class of all bi-quadratic positive real functions. This aspect of the research is directed to answering the question: `"what is the best possible system performance achievable using any simple passive mechanical network compensator?" The study makes use of computer simulations, which exploit a state-of-the-art motorcycle model whose parameter set is based on a Suzuki GSX-R1000 sports machine. The results show that, compared with a conventional steering damper, it is possible to obtain significant improvements in the dynamic properties of the primary oscillatory modes, known as 'wobble' and 'weave'.

Wednesday, 30th January 2008, 2:00pm, LT1

NOTE: usual time but different room; LT1 is the lecture room on the 1st floor.

Non-uniform Small-gain Theorems for Systems with Unstable Invariant Sets and Their Applications

Dr Ivan  Tyukin

Department of Mathematics, University of Leicester

ABSTRACT 

We consider the problem of asymptotic convergence to invariant sets in interconnected nonlinear dynamic systems. Standard approaches often require that the invariant sets be uniformly attracting, e.g. stable in the Lyapunov sense. This, however, is neither a necessary requirement, nor is it always useful. Systems may, for instance, be inherently unstable (e.g. intermittent, itinerant, meta-stable) or the problem statement may include requirements that cannot be satisfied with stable solutions. This is often the case in general optimization problems and in nonlinear parameter identification or adaptation. Conventional techniques for these cases rely either on detailed knowledge of the system's vector-fields or require boundeness of its states. The presently proposed method relies only on estimates of the input-output maps and steady-state characteristics. The method requires the possibility of representing the system as an interconnection of a stable, contracting, and an unstable, exploratory part. We illustrate with examples how the method can be applied to problems of analyzing the asymptotic behavior of locally unstable systems as well as to problems of parameter identification and adaptation in the presence of nonlinear parametrizations. The relation of our results to conventional small-gain theorems will be discussed.

Wednesday, 28 November 2007, 2:00pm, MacLellan Room

Combining Monte Carlo and worst-case methods for trajectory prediction in air traffic control

Mr Emanuele Crisostomi, University of Pisa, Italy 

ABSTRACT

This talk illustrates, through a case study, a novel combination of probabilistic Monte Carlo methods and deterministic worst-case methods to perform model-based trajectory prediction in Air Traffic Control. The objective is that of computing and updating predictions of the trajectory of an aircraft on the basis of received observations. It is assumed that uncertainty in computing the predictions derives from observation errors, from the action of future winds and from inexact knowledge of the mass of the aircraft. Our novel approach provides worst-case prediction sets in which the future trajectory of the aircraft is guaranteed to belong and, at the same time, an empirical distribution of the most probable trajectories which can be used to compute various estimates such as the probability of conflict and the expected time of arrival. The case study is developed using the aircraft performance model developed by the EUROCONTROL Experimental Centre in BADA (Base of Aircraft DAta).

Wednesday, 24 October 2007, 2:00pm, MacLellan Room

Studies of feedback interconnections: A stability analysis result and systems biology modelling

Dr Alexander Lanzon, University of Manchester

ABSTRACT

This talk has two parts to it: In the first part, a stability analysis result is presented which has similar applicability to the small-gain and passivity theorems, but is applicable to a different class of systems. This result has important engineering implications on stability robustness to spill-over dynamics in lightly-damped structures. In the second part, the life cycles of the E. Coli bacterium when infected by the Bacteriophage-\lambda virus will be modelled. The corresponding gene regulatory network behaves like a bi-stable toggle switch. It will be shown how "breaking-the-loop" to perform open-loop measurements, together with fixed-point analysis and control-like ideas can assist biologists in their studies to produce effective models. The underlying connection between the first part and the second part of the talk is the study of feedback interconnections. However, the talk will not attempt to make any substantive connection between the two parts as feedback interconnections in biological systems tend to be very complex and results like those presented in the first part of the talk can only be considered as initial steps towards more complete understanding of properties of feedback.

Wednesday, 17 October 2007, 2:00pm, MacLellan Room

Network-based coordinated predictive control of flocks

Dr Hai-Tao Zhang

Huazhong (Central China) University of Science and Technology

ABSTRACT

In this paper, by introducing a predictive mechanism with small-world connections, we propose a new motion protocol for self-driven flocks. The small-world connections are implemented by randomly adding long-range interactions from the leader to a few distant agents, namely pseudo-leaders. The leader can affect them, thereby influencing all the other agents through them much more efficiently. Moreover, these pseudo-leaders are capable of predicting the dynamics of the network several steps ahead and using this information in decision making towards coherent flocking. It is shown that drastic improvement can be achieved in terms of both the consensus performance and the communication cost. In natural science, this study provides support for the idea that some predictive mechanisms exist in widely-spread biological swarms, flocks, and schools. From the industrial engineering point of view, the current protocol allows for a significant increase in the cohesive and formative flocking performance at a fairly low cost of adding a few long-range links embedded with predictive capabilities. More importantly, inclusion of an efficient predictive mechanism allows for not only a significant increase in the speed of convergence toward consensus but also a reduction of the communication energy required to achieve a predefined consensus performance.