![[The University of Leicester]](unilogo.gif)
Professor Christopher Edwards
Christopher Edwards
- Chair of MSc Exam Board
- Chair of MSc Board of Studies
Professor
Control and Instrumentation Research Group
BSc, PhD, MIMA, MIEEE, CMath
T: +44 (0)116 223 1303
F: +44 (0)116 252 2619
E: chris.edwards@le.ac.uk
Location: Room 901, Engineering Tower
Short-Biography
Prof. Christopher Edwards was born in Swansea, South Wales. He graduated from Warwick University in 1987 with a BSc honours in Mathematics. In 1991, he moved to Leicester University as a postgraduate student in the Engineering Department funded by a British Gas Research Scholarship and was awarded a Ph.D. in 1995. He was appointed as a Lecturer in Control Engineering in the Department of Engineering at Leicester University in 1996, promoted to Senior Lecturer and Reader in 2004 and 2008 respectively, and awarded a personal chair in 2010. He is a member of the IEEE and a member of the IMA (which constitutes chartered mathematician status). He is the author of over 220 refereed papers and the co-author of a book ‘Sliding mode control: theory and applications’ (Taylor & Francis, 1998) and co-editor of the monograph ‘Advances in Variable Structure and Sliding Mode Control’ (Springer-Verlag, 2006). He is one of the editors of the recent book 'Fault Tolerant Flight Control' (Springer-Verlag, 2010) describing the results of the GARTEUR AG16 Action Group on fault tolerant control.
Main Research Interests:
Prof. Edwards' main reserach interest is in the area of ‘sliding modes’. The earliest work in this field of research considered sliding modes in the context of control. The approach involves forcing the closed-loop system trajectories to evolve along a surface in the state-space by means of a nonlinear control strategy. The closed-loop system performance is specified by appropriate surface selection, and robustness is ensured via a control law which forces the states to remain on the surface. Theoretically sliding mode controllers are able to completely reject the effect of a class of uncertainties - known as matched uncertainties. This unique robustness property has stimulated research in this area for over two decades.
Historically, the theoretical development of sliding mode control took place under the assumption that all the states of the system were available for use in the control law. From an engineering perspective however, this assumption is untenable. In real systems only a subset of this information is available in the form of measurements from appropriately located sensors. The development of sliding mode theory for the situation where only measurement information is available has been an under-pinning theme of my research work for the last decade. This is a much more difficult design problem, but important theoretical work has shown that the problem of synthesizing numerically the parameters in sliding mode control schemes can be posed in a convex optimization framework. This has enabled existing commercially available optimization software to be used to obtain the parameters in a very efficient way. The use of Linear Matrix Inequality methods has significantly increased the potential for using sliding mode schemes on complex uncertain engineering problems.
Another strand of work has explored the use of sliding mode observers for Fault Detection and Isolation i.e. monitoring a system and detecting unexpected faults resulting from component degradation/failures and/or sensor/actuator malfunctions. The novelty of this approach lies in the ability of sliding mode observers to reconstruct un-measurable signals in the process being monitored, by appropriate scaling and filtering of the so-called ‘equivalent output error injection’. This approach is quite different from typical residual generation methods for fault detection. Reconstruction approaches attempt to capture both the magnitude and ‘shape’ of the faults, and as a result, both detection and isolation are handled simultaneously. By direct reconstruction, short-term faults, which quickly clear themselves, can easily be distinguished from persistent effects because there are no dynamics associated with the residuals. The fact that even in the presence of faults, the output of the sliding mode observer still perfectly tracks the plant output, means residuals formulated in the usual way, i.e. as functions of the output estimation error, would always be zero. However as a consequence, the effect of the faults is seen through the fact that the equivalent output error injection term must compensate for the fault in order to maintain sliding. Furthermore, the fact that the faults are reconstructed allows the possibility of using the reconstructions to compensate for the fault effects – for instance by directly ‘correcting’ the output of a faulty sensor to achieve fault tolerant control. On-going work is applying these ideas to aerospace control problems within the context of the GARTEUR (Group for Aeronautical Research and Technology in Europe) Action Group on Fault Tolerant Control FM-AG16. The main objective of AG16 is to demonstrate the capabilities of Fault Detection and Isolation methods applied to realistic, nonlinear problems and to assess their contribution to flight safety. As part of this activity sliding mode schemes have been tested on the SIMONA motion simulator at the Technical University of Delft. It has been shown that sliding mode schemes in conjunction with so-called control allocation, have the capability to maintain a good level of performance even in the face of total failures of certain actuators, which currently would render the aircraft difficult to fly, and in certain cases, has resulted in the loss of the aircraft. A new ESPRC grant in conjunction with Airbus will consider these ideas within the context of ‘Active Aircraft’.
Books
• C. Edwards, E. Fossas Collet and L. Fridman, Advances in Variable Structure and Sliding Mode Control, Springer-Verlag, 2006.
• C. Edwards and S.K. Spurgeon, Sliding Mode Control: Theory and Applications, Taylor & Francis, 1998.
Contributions to Edited Books
• C. Edwards and T. Floquet and S.K. Spurgeon, `Circumventing the relative degree condition in sliding mode design', in `Modern Sliding Mode Control Theory', by G. Bartolini , L. Fridman, A Pisano and E. Usai (Eds) Springer-Verlag, pp 120-137, 2008.
• C. Edwards, S.K. Spurgeon, C.P. Tan and N. Patel, `Sliding Mode Observers', in `Mathematical Methods for Robust and Nonlinear Control', M.C. Turner and D.G. Bates (Eds), Springer-Verlag, pp 221-242, 2007.
• C. Edwards and C.P. Tan, `Robust Fault Detection Using Sliding Mode Observers', in `Advances in Variable Structure and Sliding Mode Control', C. Edwards, E. Fossas Collet and L. Fridman (Eds), Springer-Verlag, pp 293-312, 2006.
• N. Patel, C. Edwards and S.K. Spurgeon, `A Sliding Mode Scheme for Optimal Braking and Estimation of Road/Tyre Friction', in `Advances in Variable Structure and Sliding Mode Control', C. Edwards, E. Fossas Collet and L. Fridman (Eds), Springer-Verlag, pp 375-394, 2006.
• C.P. Tan and C. Edwards, `Sliding mode observers for robust fault reconstruction in nonlinear systems', in `Advances in Nonlinear Control', A.S.I. Zinober and D.H. Owens (Eds), Springer-Verlag, pp 373-383, 2002.
• C. Edwards, S.K. Spurgeon and C.P. Tan, `On the Development and Application of Sliding Mode Observers', in `Variable Structure Systems: Towards the 21st Century', X.Yu and J.X. Xu (Eds), Springer-Verlag, pp 253-282, 2002.
• C. Edwards and S.K. Spurgeon, `Dynamic sliding mode control and output feedback', in `Sliding Mode Control in Engineering', W. Perruquetti and J.P. Barbot (Eds), Marcel Dekker, pp 131-162, 2002.
• G. Herrmann, S.K. Spurgeon and C. Edwards, `On the discretization of sliding mode-like controllers', in `Nonlinear Control in the Year 2000', A. Isidori, F. Lamnabhi-Lagarrigue and W. Respondek (Eds), Springer-Verlag, pp 481-496, 2001.
• G. Herrmann, S.K. Spurgeon and C. Edwards, `A robust sliding mode output tracking control for a class of relative degree zero and non-minimum phase plants: a chemical process application', in`Advances in Variable Structure Systems: analysis, integration and applications', X.H. Yu nd J.X. Xu (Eds), World Scientific (Singapore), pp 209-218, 2000.
• C. Edwards and S.K. Spurgeon, `Nonlinear Control of a Gas Fired Furnace', Chapter 6 in `Mechatronics Systems Techniques and Applications', C.T. Leondes (Ed), Gordon Breach Science Publishers, New Jersey, pp 273-308, 2000.
• R. Davies, C. Edwards and S.K. Spurgeon, `Robust Tracking with a Sliding Mode', Chapter 3 in `Variable Structure and Lyapunov Control', A. Zinober (Ed), Springer-Verlag, pp 51-71, 1994.
Selected Journal Papers
• H. Alwi, C. Edwards, O. Stroosma and J.A. Mulder, `Piloted Sliding Mode FTC Simulator Evaluation for the EL AL Flight 1862 Incident', AIAA Journal of Guidance and Control
• T. Floquet, C. Edwards and S. K. Spurgeon, `An output feedback sliding mode control strategy for MIMO systems of arbitrary relative degree, International Journal of Robust and Nonlinear Control.
• S. Baev, Y. Shtessel, C. Edwards, S. Spurgeon, `HOSM observer for a class of non-minimum phase causal nonlinear MIMO systems', IEEE Transactions on Automatic Control.
• S. Baev, Y. Shtessel, C. Edwards and Sarah Spurgeon, `Output feedback tracking in causal nonminimum-phase nonlinear systems using higher order sliding modes', International Journal of Robust and Nonlinear Control.
• P.P Menon and C. Edwards, `Rank constrained stabilization and synchronisation of networks', Automatica, 45, pp 2910-2916, 2009.
• C.P. Tan and C. Edwards, 'Robust fault reconstruction in linear uncertain system using multiple sliding mode observers in cascade', IEEE Transactions on Automatic Control.
• X.G. Yan, S.K. Spurgeon and C. Edwards, `Global stabilisation for a class of nonlinear time-delay systems based on dynamical output feedback sliding mode control', International Journal of Control.
• J.M. Andrade da Silva, C. Edwards and S.K. Spurgeon, `Sliding Mode Output Feedback Control based on Linear Matrix Inequality Methods for Plants with Matched and Mismatched Uncertainties', IEEE Transactions on Industrial Electronics.
• X.R. Han, E. Fridman, S.K. Spurgeon and C. Edwards, `On the Design of Sliding Mode Static Output Feedback Controllers for Systems with state Delay', IEEE Transactions on Industrial Electronics.
• P. Menon and C. Edwards, `Static output feedback stabilisation and synchronisation of complex networks with H2 performance', International Journal of Robust and Nonlinear Control, 2009.
• X.G. Yan, S.K. Spurgeon and C. Edwards, `Static output feedback sliding mode control for time-varying delay systems with time-delayed nonlinear disturbances', International Journal of Robust and Nonlinear Control.
• X.G. Yan, S.K. Spurgeon and C. Edwards, `On discontinuous static output feedback control for linear systems with nonlinear disturbances', Systems and Control Letters .
• H. Alwi, C. Edwards and C.P. Tan, 'Sliding Mode Estimation Schemes for Incipient Sensor Faults', Automatica, 2009.
• X.G. Yan and C. Edwards, `Adaptive sliding mode observer-based fault reconstruction for nonlinear systems with parametric uncertainties', IEEE Transactions on Industrial Electronics, 55, pp 4029-4036, 2008.
• A. Seuret, C. Edwards and S.K. Spurgeon, `Static output feedback sliding mode control design via an artificial stabilizing delay', to IEEE Transactions on Automatic Control.
• X.G. Yan and C. Edwards, `Fault estimation for single output nonlinear systems using an adaptive sliding mode observer', IET Control Theory and Applications, 2, pp 841-850, 2008.
• H. Alwi, C. Edwards, O. Stroosma and J.A. Mulder, `Fault Tolerant Sliding Mode Design with Piloted Simulator Evaluation', AIAA Journal of Guidance and Control, 31, pp 1186-1201, 2008.
• H. Alwi and C. Edwards, `Fault tolerant control using sliding modes with online control allocation', Automatica, 44, pp 1859-1866, 2008.
• G. Herrmann, S.K. Spurgeon and C. Edwards, `Conditions for Lp-gain stability recovery within discretized nonlinear control systems', Automatica, 44, pp 1045-1054, 2008.
• H. Alwi and C. Edwards, `Fault Detection and Fault Tolerant Control of a Large Civil Aircraft Using a Sliding Mode Based Scheme', IEEE Transactions on Control System Technology, 16, 499-510, 2008.
• C. Edwards X.G Yan and S.K. Spurgeon, `On the Solvability of the Constrained Lyapunov Problem', IEEE Transactions on Automatic Control, 52, pp 1975-1981, 2007.
• N. Patel, C. Edwards and S.K. Spurgeon, `Optimal Braking and Estimation of Tyre Friction in Automotive Vehicles Using Sliding Modes', International Journal of Systems Science, 38, pp 901-912, 2007.
• X.G. Yan and C. Edwards, `Decentralized robust FDI for large-scale systems using a sliding mode observer', International Journal of Control, 81, pp. 591-606, 2008.
• N.O. Lai, C. Edwards and S.K. Spurgeon, `On output tracking using dynamic output feedback discrete-time sliding mode controllers', IEEE Transactions on Automatic Control, 52, pp 1982-1987, 2007.
• L. Fridman, Y.B. Shtessel, C. Edwards and Y.G. Yan,`Higher order sliding modes observer for state estimation and input reconstruction in nonlinear systems', International Journal of Robust and Nonlinear Control, 18, pp 399 - 412, 2007.
• G. Herrmann, C. Edwards, B. Hredzak, V. Venkataramanan, S.K. Spurgeon, `A novel discrete-time sliding mode technique and its application to a HDD dual-stage track-seek and track-following servo system', International Journal of Adaptive Control and Signal
Processing, 22 pp 344 - 358, 2007.
• X.G. Yan and C. Edwards, `Nonlinear robust fault reconstruction and estimation using a sliding mode observer, Automatica, 43, pp 1605-1614, 2007.
• T. Floquet, C. Edwards and S. K. Spurgeon, `On sliding mode observers for systems with unknown inputs', International Journal of Adaptive Control and Signal Processing, 21, pp 638-656, 2007.
• X.G. Yan and C. Edwards, `Sensor fault detection and isolation for nonlinear systems based on sliding mode observers', International Journal of Adaptive Control and Signal Processing, 21, pp 657-673, 2007. 2007.
• K.Y Ng, C.P. Tan, C. Edwards and Y.C. Kuang, `New results in robust actuator fault reconstruction for linear uncertain systems using sliding mode observers', International Journal of Robust and Nonlinear Control, 17, pp 1294-1319, 2007.
• X.G. Yan, S.K. Spurgeon and C. Edwards, `Decentralized sliding mode control for nonminimum phase nonlinear interconnected systems based on a reduced-order compensator', Automatica, 43, pp 1605-1614, 2007.
• C. Edwards and C.P. Tan, `A comparison of sliding mode and unknown input observers for fault reconstruction', European Journal of Control, 16, pp 245-260, 2006.
• C. Edwards and C.P. Tan, `Sensor fault tolerant control using sliding mode observers', Control Engineering Practice, 14, pp 897-908, 2006.
• N.O. Lai, C. Edwards and S.K. Spurgeon, `Discrete output feedback sliding mode control with integral action', International Journal of Robust and Nonlinear Control, 16, pp 21-43, 2006.
• C. Edwards, R.G. Hebden and S.K. Spurgeon, `Sliding Mode Observers for Vehicle Mode Detection', Journal of Vehicle Systems Dynamics, 42, pp 823-843, 2005.
• C. Edwards, N.O. Lai and S.K. Spurgeon, `On discrete dynamic output feedback min-max controllers', Automatica, 41, pp 1783-1790, 2005.
• X.G. Yan, S.K. Spurgeon and C. Edwards `Dynamic Output feedback sliding mode control for a class of nonlinear system with mismatched uncertainty', European Journal of Control, 11, pp 1-10, 2005.
• X.G. Yan, C. Edwards, S.K. Spurgeon and J.A.M. Bleijs, `Decentralized sliding mode control for multi-machine power systems using only output information', Proceedings of the IEE Part , 115, pp 627-635, 2004.
• C. Edwards, `A Practical Method for the Design of Sliding Mode Controllers Using Linear Matrix Inequalities', Automatica, 40, pp 1761-1769, 2004.
• X.G. Yan, C. Edwards and S.K. Spurgeon, `Decentralized robust sliding mode control for a class of nonlinear interconnected systems by static output feedback', Automatica, 40, pp 613-620, 2004.
• R.G. Hebden, C.Edwards and S.K. Spurgeon, `Automotive stability in a split-mu manoeuvre using an observer based sliding mode controller' Vehicle System Dynamics, 41, pp 181-203, 2004.
• N.O. Lai, C. Edwards and S.K. Spurgeon, `On discrete time output feedback min-max Controller', International Journal of Control, 77, pp 554-561, 2004.
• C. Edwards and S.K. Spurgeon, `On Linear Matrix Inequality Methods for Designing Sliding Mode Output Feedback Controllers', IEE Proc. Control Theory Applications, 150, pp 539-545, 2003.
• C. Edwards, S.K. Spurgeon and R.G. Hebden, `On the design of sliding mode output feedback controllers, International Journal of Control, 76, pp 893-905, 2003.
• C.P. Tan and C. Edwards, `Sliding Mode Observers for Robust Detection and Reconstruction of Actuator and Sensor Faults', International Journal of Robust and Nonlinear Control, 13, pp 443-463, 2003.
• G. Herrmann, S.K. Spurgeon and C. Edwards, `A Model-Based Sliding Mode Control Methodology Applied to the HDA-Plant', Journal of Process Control, 13, pp 129-138, 2003.
• C.P. Tan and C. Edwards, `Sliding Mode Observers for Detection and Reconstruction of Sensor Faults', Automatica, 38, pp 1815-1821, 2002.
• C.P. Tan and C. Edwards, `An LMI Approach for Designing Sliding Mode Observers', International Journal of Control, 74, pp 1559-1568, 2001.
• G. Herrmann, S.K. Spurgeon and C. Edwards, `A Robust Sliding Mode Output Tracking Control for a Class of Relative Degree Zero and Non-Minimum Phase Plants: a Chemical Process Application', International Journal of Control, 72, pp 1194-1209, 2001.
• C. Edwards A. Akoachere and S.K. Spurgeon, `Sliding Mode Output Feedback Control Design Using Linear Matrix Inequalities', IEEE Transactions on Automatic Control, 46, pp. 115-119,2001.
• C. Edwards and S.K. Spurgeon, `A Sliding Mode Observer Based FDI Scheme for the Ship Benchmark', European Journal of Control, 6, pp. 341-356, 2000.
• C. Edwards, S. Spurgeon and A. Akoachere, `A Sliding Mode Static Output Feedback Controller Based on Linear Matrix Inequalities Applied to an Aircraft System', Journal of Dynamics Systems, Measurement and Control, 122, pp. 656-662, 2000.
• C. Edwards and S.K. Spurgeon, `On the Limitations of some Variable Structure Output Feedback Controller Designs', Automatica, 36, pp 743-748, 2000.
• A. Benchaib and C. Edwards, `Nonlinear Sliding Mode Control of an Induction Motor', International Journal of Adaptive Control and Signal Processing, 14, pp 201-221, 2000.
• C. Edwards, S.K. Spurgeon and R.J. Patton, `Sliding Mode Observers for Fault Detection', Automatica, 36, pp 541-553, 2000.
• A.I. Bhatti, S.K. Spurgeon, C. Edwards, and R. Dorey, `Sliding mode control configurations for automotive control', International Journal of Adaptive Control and Signal Processing, 13, pp 49-69, 1999.
• C. Edwards and I. Postlethwaite, `An Anti-windup Scheme with Closed-loop Stability Considerations', Automatica, 35, pp 761-765, 1999.
• C. Edwards and S.K. Spurgeon, `Compensator Based Output Feedback Sliding Mode Control Design', International Journal of Control, 71, pp 601-614, 1998.
• C. Edwards and I. Postlethwaite, `Anti-windup and Bumpless-transfer Schemes', Automatica, 32, pp 199-210, 1998.
• C. Edwards and S.K. Spurgeon, `Sliding Mode Output Tracking with Application to a Multi-variable High Temperature Furnace Problem', International Journal of Robust and Nonlinear Control, 7, pp 337-351, 1997.
• C. Edwards and S.K. Spurgeon, `Robust Output Tracking Using a Sliding Mode Controller-Observer Scheme', International Journal of Control, 64, pp 967-983, 1996.
• C. Edwards and S.K. Spurgeon, `Sliding Mode Stabilisation of Uncertain Systems Using Only Output Information', International Journal of Control, 62, pp 1129-1144, 1995.
• C. Edwards and S.K. Spurgeon, `On the Development of Discontinuous Observers', International Journal of Control, 59, pp 1211-1229, 1994.
Current Teaching Responsibilities:
• EG1080 Programming and Numerical Methods
• EG2030 Control
• EG2010 Mathematics 3
• EG4011/EG7040 Nonlinear Control
Technical Committee Membership
• IEEE technical committee on Variable Structure Systems
• IFAC Technical Committee on Control System Design.
• Group for Aeronautical Research and Technology in Europe (GARTEUR) on Fault Tolerant Control 2005-2008.
Journal Editorial Boards
• Member of the editorial board of the IMechE Journal of Systems and Control
• Associate Editor of the Asian Journal Control
• Associate Editor of the International Journal of Systems Science
• Subject Editor for the International Journal of Robust and Nonlinear Control
Research Grants
1/5/99 - 30/4/02 EPSRC (P-I): 'Sliding mode observer based techniques for robust fault detection and isolation', £55K
1/9/00 - 31/8/03 EPSRC Industrial CASE with TRW Automotive (P-I): 'Output feedback sliding mode control applied to automotive problems', £52K
1/7/01 - 30/6/03 Royal Society (C-I): 'On the development of an intelligent VSC technique and its application', £10K
1/10/01 - 30/9/04 EPSRC (C-I): 'Open problems in the area of sliding mode control of uncertain non-minimum phase systems using only output information', £156K
1/4/04 - 31/3/07 EPSRC (P-I): 'Robust fault detection and isolation using sliding mode observers', £196K
1/10/05 - 30/9/06 Royal Academy of Engineering/Leverhulme Senior Research fellowship (P-I), £40K
1/11/05 - 31/1/06 BAE Systems SEAS DTC (C-I): 'Systems Engineering and Integrated Systems for Defence: Autonomous and Semi-autonomous Vehicles', SE02, £40K
1/12/05 - 30/11/10 EPSRC Platform Grant (C-I), 'Control of complex systems', £434K
1/10/06 - 30/9/09 EPSRC (C-I), 'Robust output feedback sliding mode control for time-delay systems', £366K
1/9/07 - 31/8/08 EPSRC-Airbus (P-I), 'A sliding mode approach for active fault tolerant control and estimation', £107K
1/9/08 - 31/8/09 EPSRC-Airbus (P-I), 'A sliding mode approach for control and estimation in active aircraft', £105K
1/4/09-1/8/09, European Space Agency (P-I), “SATFDI: Modern Control Techniques Applied to Satellite FDIR”, €32K
1/9/09-31/8/11 FONCICYT (50% EU, 50% Mexico National), (P-I), “Control & Monitoring via Sliding Modes for Process Automation & Energy Production”, €12K
1/4/09-1/8/09, European Commission FP7 (P-I), “ADDSAFE: Advanced Fault Diagnosis for Safer Flight Guidance and Control”, €482K
