Professor Shankar Bhattacharyya, from the Department of Electrical and Computer Engineering at the Texas A&M University, USA, and professor Keel Lee, from the Department of Electrical and Computer Engineering at the Tennessee State University, USA, visited Seoul National University and gave a series of lectures on robust control. Prof. Bhattacharyya and prof. Lee have collaborated since the 90s and published two books, namely, “Linear Multivariable Control System” and “Linear Control Theory: Structure, Robustness, and Optimization”. The lecture was based on these books and was organized into two parts: ‘Robust Control: The Parametric Approach’ and ‘Modern PID Control’.
In the first part, prof. Bhattacharyya and prof. Lee emphasized that controllers should guarantee robust stability of the closed loop system due to the presence of uncertainties. They introduced a method of designing a robust controller for a single-input single-output plant using the Hermite-Biehler theorem, the Kharitonov’s theorem, and the edge theorem. For multi-input multi-output plants, their novel approach is to convert the plant transfer function matrix into the Smith-McMillan diagonal form and apply the aforementioned method for single-input single-output plants.
The second part covered an analytical multi-objective design of a PID controller, which is a ubiquitous control technique used throughout the industry. Prof. Bhattacharyya and prof. Lee proposed a method to compute the set of PID controllers stabilizing an unknown plant with frequency response data and the ‘signature method’. It is notable that their proposed method does not require any model information and is also applicable to multivariable systems.
This seminar was a great opportunity to learn advanced techniques of robust control and PID control. We thank prof. Bhattacharyya and prof. Lee for the seminar and look forward to exchange research ideas with CDSL in the future.
