A novel hybrid controller to overcome fundamental performance limitations

December 03, 2021, zoom

Maurice Heemels

Eindhoven University of Technology, Mechanical Engineering


In this talk I will discuss a new hybrid control element, which I got very excited about recently! For this new element, we coined the term `hybrid integrator-gain system’ or HIGS for short. HIGS is a nonlinear integrator designed to avoid the limitations typically associated with linear integrators. In fact, I will show that HIGS-based control can be used to overcome well-known fundamental performance limitations related to linear time-invariant (LTI) control systems. The main design philosophy behind HIGS is built on keeping the sign of its input and output equal, thereby inducing less phase lag than a linear integrator, much like the famous Clegg integrator. The HIGS achieves the reduced phase lag by projection of the controller dynamics instead of using resets of the integrator state, which forms a potential benefit of this new control element. To formally analyze HIGS-controlled systems, I will present an appropriate mathematical framework for describing these novel systems. Based on this framework, HIGS-controlled systems are proven to be well-posed in the sense of existence and forward completeness of solutions, under suitable assumptions. Moreover, I will propose two initial approaches for analyzing (input-to-state) stability of the resulting nonlinear closed-loop systems: (i) circle-criterion-like conditions based on (measured) frequency response data, and (ii) LMI-based conditions exploiting a new construction of piecewise quadratic Lyapunov functions. Various case studies will illustrate the main results.

Speaker's Bio

Maurice Heemels received the M.Sc. degree in mathematics and the Ph.D. degree in control theory (both summa cum laude) from the Eindhoven University of Technology (TU/e), the Netherlands, in 1995 and 1999, respectively. From 2000 to 2004, he was with the Electrical Engineering Department, TU/e, as an assistant professor, and from 2004 to 2006 with the Embedded Systems Institute (ESI) as a research fellow. Since 2006, he has been with the Department of Mechanical Engineering, TU/e, where he is currently a Full Professor. He held visiting professor positions at the Swiss Federal Institute of Technology (ETH), Switzerland (2001), the University of California at Santa Barbara, USA (2008), and the University of Lorraine, France (2020). In 2004, he worked also at the company Oce (currently Canon), the Netherlands. His current research interests include hybrid and cyber-physical systems, networked and event-triggered control systems and constrained systems including model predictive control. Dr. Heemels served/s on the editorial boards of Automatica, Nonlinear Analysis: Hybrid Systems, Annual Reviews in Control, and IEEE Transactions on Automatic Control. He was a recipient of a personal VICI grant awarded by NWO (Dutch Research Council). He is the co-founder of 9 biannual PHD schools on multi-disciplinary topics such as hybrid systems, networked and large-scale systems and cyber-physical systems educating over 700 PhD students worldwide. He is a Fellow of the IEEE and is currently the chair of the IFAC Technical Committee on Networked Systems (2017-2023). He was the recipient of the 2019 IEEE L-CSS Outstanding Paper Award and was elected as a member of the IEEE-CSS Board of Governors (2021-2023).