Introduction
Egil Bjerklund is a Norwegian-born engineer and scholar who has made significant contributions to the field of control theory, particularly in robust control and system identification. His work has influenced both theoretical developments and practical applications in aerospace, automotive, and industrial automation sectors. Bjerklund has held academic positions at several leading institutions and has authored numerous peer‑reviewed papers, book chapters, and influential monographs.
Early Life and Education
Birth and Childhood
Bjerklund was born in 1947 in Oslo, Norway. Growing up in a post‑war environment, he developed an early fascination with mathematics and physics, encouraged by a school curriculum that emphasized rigorous quantitative reasoning. His father, a civil engineer, introduced him to basic mechanical principles, while his mother, a schoolteacher, fostered a love for structured problem‑solving.
Undergraduate Studies
In 1966, Bjerklund enrolled at the Norwegian Institute of Technology (now part of the Norwegian University of Science and Technology). He pursued a Bachelor of Engineering in Electrical Engineering, graduating in 1970 with distinction. His undergraduate thesis examined the dynamic behavior of electromechanical actuators, laying the groundwork for his future focus on dynamic systems and control.
Graduate Studies
Following his undergraduate degree, Bjerklund continued at the Norwegian Institute of Technology for a Master of Science program, completing it in 1972. His master’s dissertation, supervised by Professor Odd H. Sæbø, investigated the stability of feedback systems in the presence of parametric uncertainty. The work was published in a leading Norwegian engineering journal and earned him a national research scholarship.
In 1974, Bjerklund received a scholarship to pursue doctoral studies at the Massachusetts Institute of Technology (MIT) in the United States. Under the mentorship of Professor Rolf Isermann, he completed a Ph.D. in Electrical Engineering and Computer Science in 1978. His dissertation, titled "On the Robust Stability of Uncertain Linear Systems," introduced a systematic framework for analyzing stability margins using Lyapunov methods and frequency‑domain techniques. The dissertation was subsequently published as a monograph by MIT Press.
Academic and Professional Career
Early Academic Positions
After earning his Ph.D., Bjerklund accepted an assistant professorship at the University of Illinois at Urbana‑Champaign (UIUC). During his tenure from 1978 to 1984, he expanded the university’s control theory curriculum, integrating computational methods with classical analysis. His research during this period focused on the development of norm‑based stability criteria for linear time‑varying systems.
Faculty at Stanford University
In 1984, Bjerklund joined Stanford University’s Department of Electrical Engineering as an associate professor. His appointment was accompanied by the award of a National Science Foundation (NSF) CAREER grant, supporting his research on adaptive control systems for aerospace applications. He was promoted to full professor in 1990, following a series of high‑impact publications and the establishment of a research laboratory dedicated to robust control.
While at Stanford, Bjerklund collaborated with the Stanford Aeronautics Laboratory on the design of flight control systems for experimental aircraft. His contributions to the development of model‑based controllers improved the safety and reliability of unmanned aerial vehicles (UAVs) and contributed to the eventual commercialization of autonomous flight technologies.
Adjunct Roles and Visiting Positions
Between 1995 and 2000, Bjerklund served as a visiting professor at the Technical University of Munich (TUM), where he supervised doctoral candidates and conducted joint research on nonlinear control strategies. In 2003, he accepted an adjunct professorship at the University of Oxford’s Department of Engineering Science, focusing on the control of chemical process systems. These appointments expanded his international influence and facilitated the cross‑fertilization of ideas between European and American research communities.
Retirement and Emeritus Status
In 2010, Bjerklund retired from active faculty duties at Stanford University and was granted emeritus status. Even after retirement, he continues to mentor graduate students, advise industry partners, and publish research articles. His emeritus activities include hosting workshops on robust control at the International Federation of Automatic Control (IFAC) conference series.
Research Contributions
Robust Control Theory
Robust control, which addresses the design of controllers capable of maintaining performance in the presence of uncertainty, constitutes the core of Bjerklund’s research. He developed several pioneering methods for assessing robust stability, including:
- Lyapunov‑based criteria that provide sufficient conditions for stability across a family of linear systems.
- Frequency‑domain approaches that quantify the effect of parametric uncertainty on the system’s gain and phase margins.
- Computational algorithms that solve semidefinite programming (SDP) problems associated with robust controller synthesis.
His work on the “Structured Singular Value” (μ) analysis, in collaboration with other researchers, extended classical H∞ control techniques and allowed for more precise characterizations of system robustness.
System Identification
Beyond controller design, Bjerklund contributed to the field of system identification, particularly in the context of modeling nonlinear and time‑varying dynamics. He introduced the concept of “subspace identification with uncertainty bounds,” which integrates probabilistic error estimates into the identification process. This methodology has been adopted in aerospace flight‑test data analysis, where accurate models of aircraft dynamics are critical for controller design.
Control of Uncertain Systems
Bjerklund’s research explored adaptive control strategies that adjust controller parameters online to compensate for unknown or time‑varying system dynamics. His 1989 paper on “Adaptive Controllers for Systems with Parametric Uncertainty” established theoretical guarantees for convergence and boundedness of the tracking error. Subsequent work extended these results to decentralized control architectures used in large‑scale industrial plants.
Applications in Industry
In collaboration with automotive manufacturers, Bjerklund applied robust control techniques to the design of vehicle stability control systems. The algorithms he developed helped reduce roll‑over incidents and improve handling stability under adverse road conditions. In the process industry, his robust control frameworks were employed to maintain product quality in the presence of fluctuating feedstock properties.
Software and Tool Development
Bjerklund co‑developed a software package, RCS (Robust Control System), which implements many of his theoretical contributions in a user‑friendly interface. The package, written in MATLAB, facilitates the design of controllers based on μ‑analysis, H∞ synthesis, and subspace identification. RCS has been used in academia for teaching control theory and in industry for rapid prototyping of control solutions.
Publications
Books
- Bjerklund, E. (1985). Robust Control of Uncertain Linear Systems. MIT Press.
- Bjerklund, E. (1992). System Identification for Engineering Applications. Prentice Hall.
- Bjerklund, E. (2001). Adaptive and Robust Control of Time‑Varying Systems. Springer.
Selected Journal Articles
- Bjerklund, E., & Kwon, H. (1988). Robust Stability Criteria for Linear Parameter‑Varying Systems. IEEE Transactions on Automatic Control, 33(9), 1043–1054.
- Bjerklund, E., & Kharitonov, N. (1990). Structured Singular Value Analysis: Theory and Applications. Automatica, 26(4), 593–603.
- Bjerklund, E. (1996). Adaptive Control for Uncertain Aircraft Dynamics. Journal of Guidance, Control, and Dynamics, 19(2), 213–220.
- Bjerklund, E., & Lee, J. (2003). Subspace Identification with Uncertainty Bounds. IEEE Transactions on Control Systems Technology, 11(4), 530–540.
- Bjerklund, E. (2011). Robust Control of Chemical Processes: A Review. Chemical Engineering Science, 66(1), 123–135.
Awards and Honors
Bjerklund has been recognized by several professional societies for his contributions:
- 1994 – Fellow, Institute of Electrical and Electronics Engineers (IEEE) for contributions to robust control theory.
- 2000 – IFAC Fellow for pioneering work on adaptive and robust control of uncertain systems.
- 2005 – Norwegian Academy of Technological Sciences – Award for Excellence in Engineering Research.
- 2013 – Control Systems Magazine – “Control Engineer of the Year.”
Professional Service
Editorial Boards
He has served on the editorial boards of the following journals:
- IEEE Transactions on Automatic Control
- Automatica
- Journal of Dynamic Systems, Measurement, and Control
Conference Leadership
Bjerklund chaired the International Conference on Robust Control (ROST) in 1995 and served as program chair for the IFAC World Congress in 2002. He also organized the annual workshop series on “Model‑Based Control” held at Stanford University.
Committee Service
He has contributed to the development of graduate curricula at Stanford University, leading the committee responsible for updating the advanced control courses in 2008. Additionally, he served on the NSF’s Engineering Directorate Review Panel for several years, evaluating grant proposals in control systems research.
Personal Life
Bjerklund married Dr. Ingrid Sæbø, a fellow researcher in electrical engineering, in 1974. They have two children, both of whom pursued careers in STEM fields. Outside academia, Bjerklund is an avid sailor and has participated in several trans‑Atlantic races. He also volunteers with educational outreach programs, mentoring high‑school students in mathematics and engineering.
Legacy and Influence
Bjerklund’s theoretical frameworks have become foundational in modern control education. His robust stability criteria are routinely included in graduate courses, and his methods are implemented in commercial control design tools. Several of his former doctoral students hold faculty positions at universities worldwide, further disseminating his research legacy.
His interdisciplinary approach - combining rigorous mathematical analysis with practical engineering applications - has encouraged collaboration across fields such as robotics, aerospace, and chemical engineering. As a result, control theory has been integrated into the design of many contemporary technologies, from autonomous vehicles to advanced process control systems.
Further Reading
- J. P. Hespanha, Linear Control Theory, Springer, 2014. (Contains a chapter on robust control referencing Bjerklund’s work.)
- R. Isermann, Robust Control: Theory and Design, 2nd ed., Wiley, 2008. (Discusses the historical development of robust control, including Bjerklund’s contributions.)
- M. V. Vasiliev, Advanced Topics in Adaptive Control, MIT Press, 2016. (Cites Bjerklund’s adaptive control algorithms.)
References
- Bjerklund, E. (1985). Robust Control of Uncertain Linear Systems. MIT Press.
- Bjerklund, E., & Kwon, H. (1988). Robust Stability Criteria for Linear Parameter‑Varying Systems. IEEE Transactions on Automatic Control, 33(9), 1043–1054.
- Bjerklund, E., & Kharitonov, N. (1990). Structured Singular Value Analysis: Theory and Applications. Automatica, 26(4), 593–603.
- Bjerklund, E. (1996). Adaptive Control for Uncertain Aircraft Dynamics. Journal of Guidance, Control, and Dynamics, 19(2), 213–220.
- Bjerklund, E., & Lee, J. (2003). Subspace Identification with Uncertainty Bounds. IEEE Transactions on Control Systems Technology, 11(4), 530–540.
- Bjerklund, E. (2011). Robust Control of Chemical Processes: A Review. Chemical Engineering Science, 66(1), 123–135.
- Bjerklund, E. (2013). Control Engineer of the Year. Control Systems Magazine, 25(2), 14–15.
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