Personal Information

Education

Ph.D, Dynamics and Control, December, 1993
Purdue University, West Lafayette, IN
Dissertation: "A Unified Matrix Inequality Approach to Linear Control Design"

M.S., Electrical and Electronic Engineering, March, 1990
Tokyo Institute of Technology, Tokyo, Japan
Thesis: "An Application of the Extended Kalman Filter to the Field Oriented Control of an Induction Motor"

B.S. in Electrical and Electronic Engineering, March, 1987
Tokyo Institute of Technology, Tokyo, Japan
Thesis: "On the Design of Windmill Simulator for Electrical Power Generation"

Employment/Experience

University of Virginia, Charlottesville, VA
Professor, Department of Mechanical and Aerospace Engineering                       8/2004-present
Associate Professor, Department of Mechanical and Aerospace Engineering       10/2002-8/2004
Assistant Professor, Department of Mechanical and Aerospace Engineering          5/2000-10/2002

Tokyo Institute of Technology, Tokyo, Japan
Associate Professor, Department of Control Systems Engineering                         4/1997-5/2000
Lecturer, Department of Computational Intelligence and Systems Science             5/1996-3/1997
Research Associate, Department of Systems Science                                           3/1995-4/1996

Purdue University, West Lafayette, IN
Post-doctoral Research Associate, School of Aeronautics and Astronautics         1/1994-2/1995

Professional/Academic Affiliations

• Senior Member, Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Member, American Society of Mechanical Engineers (ASME)
• Member, Society of Instrument and Control Engineers (SICE)
• Member, Sigma Gamma Tau
• Associate Editor, IFAC Automatica,  03/2004-02/2007
  
• Associate Editor, IEEE Transactions on Automatic Control, 10/1999-12/2003
• Associate Editor, Systems and Control Letters, 10/1998-present
• Editorial Board Member, Journal of SICE, 1997
• Publicity Chair, Operating Committee, IEEE Conference on Control Applications, 2004
• Secretary, Organizing Committee, SICE Annual Conference, 1998
• Technical Program Committee Member, IEEE Conference on Control Applications, 2001
• Technical Program Committee Member, IEEE Conference on Decision and Control, 1999

Honors/Awards

• NSF Career Award, National Science Foundation, Electrical and Computer Systems, 2003
• Pioneer Prize, Society of Instrument and Control Engineers, 2002 
   Annually awarded, by the largest control engineering society in Japan, for one young (40 years old or younger) researcher who made significant contributions over years that were truly original and had strong impact on the subsequent developments in the field of control.
• Outstanding Reviewer Automatica, International Federation of Automatic Control, 2001.
• Outstanding Reviewer Journal of Guidance, Control and Dynamics, American Institute of Aeronautics and Astronautics, 2000.
• Outstanding Research Paper Award,Tejima Foundation for Engineering Education, Japan, 2000.
• Who's Who in the World, Millennium Edition, Marquis Who's Who, 2000.
• Outstanding Reviewer, IEEE Transactions on Automatic Control, 1999.
• Best Paper in Session, Session: LMI-based Algorithms for Fixed-order Control Design, American Control Conference, 1997.
• Best Paper in Session, Session: Linear Matrix Inequalities in Control Theory - I, American Control Conference, 1994.
• Best Paper in Session, Session: Robust Control for Uncertain Systems, American Control Conference, 1994.
• Best Paper in Session, Session: H-infinity with Reduced Order Controller Models, American Control Conference, 1993.

Current Research Interests and Projects

• Dynamic Interaction between Biological Oscillator and Mechanical Rectifier

NSF/CMS 0201386, July 2002 - June 2005, PI: T. Iwasaki

 
Biologists have found an evidence that rhythmic animal locomotion such as walking, swimming, and flying, are realized by certain neuronal elements — the central pattern generators (CPGs). The CPG drives the animal body which in turn acts as a mechanical rectifier, when interacting with the environment, to convert the rhythmic body motion into its forward velocity. Substantial knowledge on such biological control systems has been generated in the field of neuroscience, yet it awaits full exploitation for engineering design.

The objective of this basic research is to uncover the fundamental mechanism of bi-ological oscillation and its dynamic interaction with the mechanical rectifier. In particular, the project will develop an understanding of the mechanism of animal locomotion from biological ob-servations at the neuronal level, hypothesize the knowledge as engineering principles for feedback control design, and establish a systematic procedure for designing CPG-based controllers to achieve optimally efficient autonomous locomotion.

The CPG control design problem will be addressed by breaking it down into the following tasks, based on a series of conjectures drawn from biological observations: (a) Find a mathematical model for a neuron, which is simple enough to allow for theoretical analysis but captures essential neuronal dynamics such as spike generation mechanism. (b) Develop a systematic method for designing CPGs that achieve a given frequency/phase profile. (c) Develop an optimization algo-rithm for tuning the synaptic connection parameters of CPGs to achieve the most energy efficient locomotion. (d) Experimentally validate robustness of the design procedure to be developed, in the presence of environmental uncertainty.

The PI has developed a preliminary model for Task (a) by simplifying detailed models from neuroscience within the framework of Lur’e systems which have been extensively studied in robust/nonlinear control literature. Such modeling allows Task (b) to be approached by general-ization of Lyapunov methods in which the PI has expertise and substantial experience. For Task (c), an optimization problem is mathematically formulated and gradient-based dynamic backprop-agation methods will be investigated. For Task (d) and for all other relevant studies, the PI plans to use a specific example of locomotor. The prototype mechanical rectifier (PMR) he proposes is simple enough to allow for extraction of engineering principles by theoretical analysis, simulation, and experiments. At the same time, it captures the essential dynamical mechanism of animal locomotion.

The next technological revolution seems to rely on our understanding of complex biological systems. Such understanding would enable us to develop a completely new kind of robust, adaptive, and autonomous machines. The outcome of this project will enhance the basic understanding of the mechanism underlying such sophistication, through formalization of biological knowledge on animal locomotion in terms of engineering language of feedback control. Our research will have impacts on new innovations in a variety of fields. Realizations of new type of robotic locomotion systems for space explorations would be a direct application. Physiological control of the heart beat profile for stabilization of defective heart may be another. In view of entrainment and self-excitation capabilities of CPGs, the long term implications of the knowledge to be generated may also include advent of drastically different ways for information processing.

 
 

• Modeling and Analysis of Neuronal Circuits for Locomotion with Sensory Feedback

NIH/NINDS 1 R01 NS46057-01, October 2002 - September 2006, PI: T. Iwasaki, Co-PI: W.O. Friesen (Biology)

The broad aim for this project is to enhance the understanding of biological information processing mechanisms. The immediate goals are to uncover the fundamental roles of sensory feedback mechanisms in the neuronal control of animal locomotion and to establish mathematical models that predict the dynamical behavior of and supply missing information about the biological system. More specifically, the aims are to I) perform biophysical and physiological experiments on leech preparations to collect neuronal and mechanical input/output data needed for quantitative models, II) develop a mathematical model of the neuronal control system for leech swimming that includes sensory feedback,  III) predict the effects of sensory feedback through numerical simulations of the model, and IV) test these predictions through physiological experiments on leech preparations.

This project employs the Lur'e model for neuronal dynamics, recently developed by the PI, as a basis for the modeling of neurodynamic feedback control system of leech swimming. The class of Lur'e systems has been extensively studied in the systems and control discipline and thus a variety of mathematical analysis tools are available. The project develops dynamical models (differential equations) of the leech locomotion control system, consisting of the central oscillator, muscle actuation by motoneurons, body-fluid interactions, and sensory feedback from stretch receptors, through parameter identifications based on experimental observations. Physiological experiments will be conducted on dissected and intact leech preparations to obtain explicit values for model parameters and to test hypotheses generated by experiments performed on the model.

The collaborative engineering-neurophyhsiological research proposed here is part of a broad effort to discover general principles for the neuronal control of animal movements. Because of the functional similarity, insights gained from the proposed research on leech swimming can be expected to increase our understanding of the neuronal control of rhythmic movements generally.  Potential applications of the knowledge to be generated include insights into the cause of walking disability and development of rehabilitation methodologies, in addition to immeidate applications to feedback control design for rhythmic pattern generation.
 

 

• Feedback Control Theory for Biological Pattern Generation

NSF/ECS/CAREER 0237708, February 2003 - January 2008, PI: T. Iwasaki

            

            The overall goal of this career proposal is to explore the purely interdisciplinary subject of feedback control system design for generation of rhythmic patterns found in animal locomotion, and to develop effective pedagogical methods for inspiring engineering students with benefits of biological knowledge in the context of systems and control. Our specific goals are to (I) develop an orbital trajectory analysis method for a class of nonlinear systems arising from modeling of biological pattern generators; (II) establish a method for designing a dynamical system that achieves pattern generation with a prescribed oscillation profile; (III) revise the dynamics and control curriculum to provide a broader view of ``systems'' through crossdisciplinary training in neuroscience; (IV) integrate the bio-control research into the science and engineering education at broad levels including K-12 and college undergraduate; (V) broadly disseminate the results of the proposed activities. Our methods and procedures to achieve these goals are to (I) mathematically formulate an oscillation analysis problem and derive a solution using tools from robust control theory, examine the degree of conservatism exploiting the biological knowledge of particular central pattern generator (CPG) architectures; (II) use the analysis result in I as a basis for developing a general theory for the design of CPGs utilizing linear matrix inequality methods, test the applicability of the design conditions against the CPGs known from biology; (III) improve an undergraduate course on systems modeling by introducing neuronal modeling and pattern generation mechanism, develop a new graduate course on robust and nonlinear control for regulation and biological oscillation; (IV) develop research-based educational tools through multidisciplinary, teamworking, senior thesis projects. Use the tools to stimulate K-12 and undergraduate students' intellectual curiosity into engineering and science through a series of outreach/educational activities; (V) utilize conference presentations, publications in archival journals, invited seminars, and possibly tutorial workshops in major international conferences.

The central theme of feedback control theory has been the regulation around an equilibrium point of a dynamical system. In contrast, much less attention has been paid to control specifications involving periodic motion (or oscillation) generation despite their practical importance. The basic research outlined in this proposal will provide an initial stepping stone toward a new control paradigm that focuses on autonomous pattern generation by feedback dynamics. In particular, the project will establish a systematic method for analysis and design of pattern generators through the exploitation of biological knowledge on neuronal oscillators. The crossdisciplinary research activities over biology and control fields are integrated into educational activities at all levels. The revised curriculum will provide undergraduate and graduate students with a broader perspective on engineering problems. The senior thesis project will develop students with team-oriented problem-solving skills in a multidisciplinary environment. The outreach activities will contribute to improve scientific literacy of K-12 students. 

 

More details of the current research projects can be found in:

           
Z. Chen and T. Iwasaki. "State pattern generation of rectifier systems by circulant oscillators," Proc. MTNS, 2006.  PDF
Z. Chen and T. Iwasaki. "Exact synthesis of central pattern generators: a circulant paradigm," Proc. American Control Conference, 2006.  PDF
T. Iwasaki. "Analysis and synthesis of central pattern generators via multivariable harmonic balance," Proc. ACC, 2006.  PDF
T. Iwasaki.and M. Zheng "Sensory feedback mechanism underlying entrainment of central pattern generator to mechanical resonance," Biological Cybernetics, 2006.  PDF
T. Iwasaki, "Neuronal oscillator: A new perspective in control," Seminar Talk, 2002.   PPT Presentation
T. Iwasaki and M. Zheng, "The Lur'e model for neuronal dynamics," Proc. IFAC World Congress, 2002.  PDF
T. Iwasaki, "Robust self-excitation by biological oscillators," Proc. IFAC World Congress, 2002.  PDF
T. Iwasaki and M. Zheng, "What makes biological oscillators achieve robust self-excitation?," Proc. American Control Conference, 2003. PDF
T. Iwasaki, "Cybernetic Control Lab" Activity Report, October 2004.   PPT Presentation

Past Research Interests and Projects

  NASA/NIA 3013-UV, January 2003 - , PI: H. Haj-Hariri, Co-PIs: H. Bart-Smith, T. Iwasaki

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Morphing:  A key emerging technology is in the development of synthetic shape morphing structures and actuators.  The Morphing Structures Group at UVA has considerable experience in the design and testing of lightweight shape morphing systems.  A major contribution of this group is in the integration of linear actuator devices and materials into statically determinant trusses.  Actuation of the active material or device does not generate strain energy within the inactive members of the structure, therefore not diminishing the morphing system’s ability to overcome large restraining forces and moments.  A wide choice of actuators is available, including electroactive polymers, shape memory alloys (SMAs), micro-pneumatic devices, as well as magneto and electrostrictive and piezoelectric materials.  SMAs and EAPs are of particular interest.  Many of these materials can be made in fiber or ribbon form and weaving them facilitates the creation of hierarchical structures containing sensors, power delivery and linear control filaments.  We have considerable experience in the use of SMAs.  Bart-Smith recently used SMAs to develop a successful shape morphing structural panel.  A cantilever beam using a lightweight, near statically determinant cellular metal truss core and Ni-Ti SMA face sheets was used to demonstrate the working principles.

            

            Control:  Iwasaki (with NIH/NSF funding) has developed a neuronal controller, which is motivated by considering that a flyer or swimmer can be viewed as a AC-to-DC converter (periodic lateral movements resulting in linear movement), while biological neurons are the opposite (a constant current injection leading to a sequence of electrical pulse firings).  With this elegantly insightful (and original) observation, using some similarly insightful models, a neuronal controller was developed and applied to nonlinear oscillators that were tasked with a certain objective.  In very few cycles the objective was achieved.  This truly-bio-inspired controller is an ideal candidate for the control of flapping or swimming.

            

            Modeling:  The development of the control algorithm, as well as the model of the actuator requires a theoretical/computational model of the flyer.  Given the complexity of the governing equations and the geometry, it is imperative to have a reduced-order model of the system, allowing for all interactions and control.  Furthermore, the model needs to be able to handle all geometries with ease.  These requirements point to the direction of an embedding model wherein the solid is embedded in a fluid and the resulting equations are then projected onto an appropriate basis for the reduction of order.  Haj-Hariri has been working on these ideas for a few years, the last two funded by NASA.

Automotive Independently Controlled Magnetic Valve

2000 Honda Research Initiation Award, January 2001 - December 2001, PI: T. Iwasaki, Co-PI: P. Allaire

The project concerns the development of a set of independently controlled electro-magnetic valves for automotive use as powertrain intake and exhaust use. In normal automotive engine design, the valve timing is dictated by the fixed engine driven camshaft or similar component. The goal of this research is a fully independent valve design which allows for specific timing scheduling and profiling to maximize the performance output of the engine. The valve has to travel 8mm in 3.6ms at the high end of the engine speed envelope (6000rpm). The major challenge for electromagnetic actuator design is to achieve such large acceleration in the presence of uncertain gas dynamic disturbance force. The important control tasks that need to be achieved include soft landing, disturbance attenuation, and energy optimization.

 

Serpentine Locomotion by Robotic Snake

Grant-in-Aid for COE Research, Ministry of Education, Japan,  April 1997 - May 2000, PI: K. Furuta

Most currently available mobile robot mechanisms for ground operations have wheels driven by some type of rotational motion generators such as an engine. Such wheeled mechanisms are relatively efficient, easy to steer, and suited for high-speed driving on a smooth surface. They are, however, not effective in rugged environments such as rough and/or muddy terrains. Mobile robots with legs are being actively researched for several reasons, including the fact that legs provide higher terrain adaptability than wheels. Even higher terrain adaptability may be achieved by multilink articulated robots that "crawl" like snakes. Beyond their adaptability to the environment, serpentine robots offer a variety of advantages over mobile robots with wheels or legs. They are robust to mechanical failure because they are modular and highly redundant. They may also perform as manipulator arms when part of the multilinked body is fixed to a platform. On the other hand, one of the main drawbacks is their poor power efficiency for surface locomotion. Another is the difficulty in analyzing and synthesizing snakelike locomotion mechanisms, which are not as simple as wheeled mechanisms. While the former is a fundamental drawback inherent with the snakelike locomotion, the latter point has been addressed by many researchers, and we hope to add another contribution to overcoming the difficulty.

In this research, we consider a snake robot without wheels that has substantial potential for adapting to the environment at the expense of power efficiency. First, we develop a mathematical model for an articulated snake robot consisting of n  rigid private with torque actuators at n-1 joints. Two models for the directional friction force acting on each link are developed and integrated into the total equations of motion for the snake robot. We then show a model transformation that decouples the dynamics into the internal shape motion (joint torques -> joint angles) and the inertial locomotion (joint angles -> inertial position and orientation). This decoupling enables us to concentrate on control of the inertial locomotion through the shape change, assuming that the shape can readily be controlled as desired via the joint actuators. We then analyze the locomotion of the snake robot with serpentine gait from the power efficiency standpoint. In particular, we investigate the shape motion that achieves the locomotion at a prescribed speed while requiring the least input power. Based on the analysis results, we determine the feedback control architecture to realize desired locomotion and propose a method for designing such controllers by suggesting an appropriate input transformation. Finally, our control strategy is experimentally validated by a five-link articulated snake robot. To our knowledge, this is the first research that addresses the problem of modeling, analysis, and feedback synthesis of serpentine locomotion by an articulated robotic snake without wheels.

 

Integrated Design of Controlled Mechanical Systems

Grant-in-Aid for COE Research, Ministry of Education, Japan,  April 1997 - May 2000, PI: K. Furuta

Designs of controlled mechanical systems have been conventionally carried out in two independent steps: the mechanical design followed by the control design. While this strategy has been successful for generating systems that work fairly well, dynamic performance specifications have become increasingly more stringent in some applications and have demanded a new design concept for effectively integrating the two steps. An important aspect of the design is that the mechanical component and the controller are in a feedback interconnection, and as such, we cannot expect that optimization on each will produce a satisfactory result. The design of each needs to take into account the limitations and capabilities of the other. The objective of this research is to uncover the fundamental nature of high quality integrated designs in the context of controlled mechanical systems, and to develop tools for design from this understanding. We focus on identifying the properties of mechanical systems that place limits on controlled performance.
 

Robust Stability and Performance Analysis of Dynamic Control Systems

Ministry of Education, Japan, April 1996 - March 1999, PI: T. Iwasaki

Performance of dynamic control systems can often be quantified as the size of certain signals within the system in response to a prescribed class of possible exogenous signals. The objective of this research is to develop systematic tools to assess performance of a certain class of dynamic systems. Such tools are based on mathematical models of real systems and thus their applicability is subject to inherent modeling errors. Our approach will explicitly take such uncertainties into account and provide method for calculating robust performance measures, that is, estimates for the worst case performances. The class of systems treated is fairly large, including linear systems with time-varying parameters, uncertain delays, actuator saturations, and general static nonlinearities.

Teaching Activities

• MAE371 Mechanical Systems Modeling
• MAE752 State Space Linear Control Systems
• MAE753 Optimal Dynamical Systems




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Book and Journal Publications

S. Hara and T. Iwasaki, "Finite frequency characterization of easily controllable plant toward structure/control design integration," pp.183-196, Control and Modeling of Complex Systems, Editors: K. Hashimoto, Y. Oishi, and Y. Yamamoto, Birkhauser, 2003.

            T. Iwasaki and M. Fu, "Regional H_2 performance synthesis," Chapter 6 of Actuator Saturation Control, Editors: V. Kapila and K. M. Grigoriadis, Marcel Dekker, Inc., 2002. PDF

T. Iwasaki, "Generalized quadratic Lyapunov functions for nonlinear/uncertain systems analysis," Chapter 10 of Perspectives in Robust Control, Editor: S. O. Reza Moheimani, Lecture Notes in Control and Information Sciences 268, Springer, 2001. PDF

T. Iwasaki, "Control synthesis for well-posedness of feedback systems," Chapter 14 of Advances on LMI Methods in Control, Editors: L. El Ghaoui and S.-I. Niculescu, SIAM, 2000. PDF

R. E. Skelton, T. Iwasaki and K. Grigoriadis, "A Unified Approach to Linear Control Design," Taylor & Francis, 1997.

T. Iwasaki, "LMI and Control," Shokodo, 1997.

            T. Iwasaki and S. Hara, ``Generalized KYP lemma: Unified frequency domain inequalities with design applications,'' IEEE Transactions on Automatic Control, 2004.(To appear)

H.-J. Ahn, E.H. Maslen, and T. Iwasaki, ``Feasibility analysis for the robordynamic performance of API617,'' ASME Journal of Engineering for Gas Turbines and Power, 2004. (To appear)

E.H. Maslen, D. Montie, and T. Iwasaki, ``Robustness limitations in self-sensing magnetic bearing,''  ASME Dynamic Systems, Measurement and Control, 2004. (Provisionally accepted).

            T. Iwasaki, S. Hara, and H. Yamauchi, "Dynamical system design from a control perspective: Finite frequency positive-realness approach," IEEE Transactions on Automatic Control,  Vol.48, No.8, pp.1337-1354, 2003.

            J. A. C. Humphrey, H. Haj-Hariri, T. Iwasaki, M. Kazemi, and L. Rosales, "Modeling and controlling flow-induced suspension-head unit vibrations in hard disk drives,'' Microsystem Technologies, Vol.8, pp.375-382, 2002.

M. Saito, M. Fukaya and T. Iwasaki, "Modeling, analysis, and synthesis of serpentine locomotion with multilink robotic snake," IEEE Control Systems Magazine, Vol.22, No.1, pp.64-81, 2002. PDF

T. Iwasaki and G. Shibata, "LPV system analysis with quadratic separator for uncertain implicit systems," IEEE Transactions on Automatic Control, Vol.46, No.8, pp.1195-1208, 2001. PDF

T. Kiyama and T. Iwasaki, "State space region attaining L_2 performance for saturating control system," Transactions of SICE, Vol.37, No.4, pp.307-315, 2001.

S. Swei, T. Iwasaki, and M. Corless, "Quadratic controllability, strong controllability, and a related output feedback property," SIAM Journal on Control and Optimization, Vol.39, No.5, pp.1373-1390, 2000. PDF

T. Kiyama and T. Iwasaki, "On the use of multi-loop circle criterion for saturating control synthesis," Systems and Control Letters, Vol.41, No.2, pp.105-114, 2000.  PDF

T. Iwasaki, G. Meinsma and M. Fu, "Generalized S-procedure and finite frequency KYP lemma," Mathematical Problems in Engineering, Vol.6, pp.305-320, 2000. PDF

G. Meinsma, T. Iwasaki, and M. Fu, "When is (D,G)-scaling both necessary and sufficient," IEEE Transactions on Automatic Control, Vol.45, No.9, pp.1755-1759, 2000. PDF

T. Asai, S. Hara and T. Iwasaki, "Simultaneous parametric uncertainty modeling and robust control synthesis by LFT scaling," Automatica, Vol.36, No.10, pp.1457-1467, 2000. PDF

P. Prautsch, T. Mita, and T. Iwasaki, "Analysis and control of a gait of snake robot," Transactions of IEEJ, Industry Applications Society, Vol.120-D, No.3, pp.372-381, 2000. PDF

T. Iwasaki, "The dual iteration for fixed order control," IEEE Transactions on Automatic Control, Vol.44, No.4, pp.783-788, 1999. PDF

H. Tokunaga, T. Iwasaki and S. Hara, "Analysis and synthesis of the robust impulse-to-peak performance," Automatica, Vol.34, No.11, pp.1473-1477, 1998. PDF

G. Meinsma, M. Fu, and T. Iwasaki, "Robustness of the stability of feedback systems with respect to small time-delays," Systems and Control Letters, Vol.36, No.2, pp.131-134, 1999. PDF

T. Iwasaki and S. Hara, "Well-posedness of feedback systems: insights into robustness analysis and approximate computations," IEEE Transactions on Automatic Control, Vol.43, No.5, pp.619-630, 1998. PDF

T. Iwasaki, R. Skelton and M. Corless, "A recursive construction algorithm for covariance control," IEEE Transactions on Automatic Control, Vol.43, No.2, pp.268-272, 1998. PDF

T. Iwasaki and M. A. Rotea, "Rank-one scaled H_infinity optimization," ASME Journal of Dynamic Systems, Measurement, and Control, Vol.119, No.3, pp.513-520, 1997. PDF

T. Iwasaki, S. Hara and M. Rotea, "Computational complexity reduction in scaled H infinity synthesis," Automatica, Vol.33, No.7, pp.1325-1332, 1997. PDF

T. Iwasaki and M. A. Rotea, "Fixed order scaled H infinity synthesis," Optimal Control Applications \& Methods, Vol.18, No.6, pp.381-398, 1997. PDF

T. Iwasaki, "Robust performance analysis for systems with structured uncertainty," International Journal of Robust and Nonlinear Control, Vol.6, pp.85-99, 1996. PDF

T. Iwasaki and R. E. Skelton, "Parametrization of all stabilizing controllers via quadratic Lyapunov functions," Journal of Optimization Theory and Applications, Vol.85, No.2, pp.291-307, 1995. PDF

T. Iwasaki and R. E. Skelton, "A unified approach to fixed order controller design via linear matrix inequalities," Mathematical Problems in Engineering, Vol.1, pp.59-75, 1995. PDF

T. Iwasaki and R. E. Skelton, "The XY-centering algorithm for the dual LMI problem: a new approach to fixed order control design," International Journal of Control, Vol.62, No.6, pp.1257-1272, 1995. PDF

T. Iwasaki and R. E. Skelton, "All low order H infinity controllers: observer-based structure and covariance bound," IEEE Transactions on Automatic Control, Vol.40, No.3, pp.512-516, 1995. PDF

R. E. Skelton and T. Iwasaki, "Increased roles of linear algebra in control education," IEEE Control Systems Magazine, Vol.15, No.4, pp.76-90, 1995. PDF

T. Iwasaki, R. E. Skelton and J. C. Geromel, "Linear quadratic suboptimal control with static output feedback," Systems and Control Letters, Vol.23, No.6, pp.421-430, 1994. PDF

T. Iwasaki and R. E. Skelton, "All controllers for the general H infinity control problem: LMI existence conditions and state space formulas," Automatica, Vol.30, No.8, pp.1307-1317, 1994. PDF

R. E. Skelton, J. Stoustrup and T. Iwasaki, "The H infinity control problem using static output feedback," International Journal of Robust and Nonlinear Control, Vol.4, pp.449-455, 1994.

T. Iwasaki and R. E. Skelton, "On the observer-based structure of covariance controllers," Systems and Control Letters, Vol.22, pp.17-25, 1994.

R. E. Skelton and T. Iwasaki, "Liapunov and covariance controllers," International Journal of Control, Vol.57, No.3, pp.519-536, 1993.

Students

NOTE: All the current students are at the University of Virginia.
^M (Co-advised by E. Maslen), ^s (Advised by S. Hara during 5/2000-3/2001), ^m (Advised by T. Mita during 5/2000-3/2001)