Sepehr Moalemi

M.Sc. Mechanical Engineering
McGill University DECAR Group

I’m finishing my Master’s degree in Mechanical Engineering (Thesis) under the supervision of Prof. James Richard Forbes at McGill’s DECAR research group. My research focuses on studying optimization algorithms through the lens of control theory. More specifically, I’m interested in analyzing the stability and robustness of popular optimization algorithms using input-output theory. Within the context of gain-scheduling dissipative systems, I have also worked on extending the existing gain-scheduling architecture to a more general class of scheduling functions and dissipative systems.

I obtained my B.Eng. in Mechanical Engineering (Honors) from McGill, with a minor in Computer Science and a minor in Mathematics. For my undergraduate thesis, I was part of the McGill Computational Aerodynamics Group under the supervision of Prof. Siva Nadarajah.

News

Sep 25, 2024 Workshop	I led an introduction to MATLAB workshop session for McGill Biomedical Engineering students. Event Site Files
Aug 21, 2024 Presentation	Presented at the 2024 IEEE Conference on Control Technology and Applications (CCTA). Event Site Abstract This paper considers gain-scheduling of very strictly passive (VSP) subcontrollers using scheduling matrices. The use of scheduling matrices, over scalar scheduling signals, realizes greater design freedom, which in turn can improve closed-loop performance. The form and properties of the scheduling matrices such that the overall gain-scheduled controller is VSP are explicitly discussed. The proposed gain-scheduled VSP controller is used to control a rigid two-link robot subject to model uncertainty where robust input-output stability is assured via the passivity theorem. Numerical simulation results highlight the greater design freedom, resulting in improved performance, when scheduling matrices are used over scalar scheduled signals. PDF Slides Code
Jul 24, 2024 Presentation	Presented at the 25th International Symposium on Mathematical Programming (ISMP). I also chaired the Optimal Control, PDE Constrained Optimization, and Multi-level Methods 1 session! Event Site Abstract In this presentation, the stability of popular first-order optimization algorithms is examined through the lens of passivity. The passivity theorem ensures input-output stability of a passive plant connected in a negative feedback loop with a very strictly passive (VSP) system. Combining existing work on control interpretation of first-order optimization algorithms with loop transformation techniques, it is shown that gradient descent (GD) can be rendered passive, while the more recent triple momentum (TM) method is input strictly passive (ISP). It is shown that the sector boundedness of the gradient of an L-smooth, m-strongly convex function renders it being VSP. Therefore, the passivity theorem can ensure input-output stability of GD when the gradient is L-smooth, m-strongly convex. Slides
Jul 10, 2024 Conference	Attended the 2024 American Control Conference (ACC). Event Site

Selected Publications

CCTA
Passivity-Based Gain-Scheduled Control with Scheduling Matrices

Sepehr Moalemi, and James R. Forbes

IEEE Conference on Control Technology and Applications (CCTA), Feb 2024

Abstract PDF Code Slides BibTeX

This paper considers gain-scheduling of very strictly passive (VSP) subcontrollers using scheduling matrices. The use of scheduling matrices, over scalar scheduling signals, realizes greater design freedom, which in turn can improve closed-loop performance. The form and properties of the scheduling matrices such that the overall gain-scheduled controller is VSP are explicitly discussed. The proposed gain-scheduled VSP controller is used to control a rigid two-link robot subject to model uncertainty where robust input-output stability is assured via the passivity theorem. Numerical simulation results highlight the greater design freedom, resulting in improved performance, when scheduling matrices are used over scalar scheduled signals.
@inproceedings{moalemi_forbes_vsp_gs_ccta, author = {Moalemi, Sepehr and Forbes, James R.}, title = {Passivity-Based Gain-Scheduled Control with Scheduling Matrices}, booktitle = {IEEE Conference on Control Technology and Applications (CCTA)}, pages = {7--13}, year = {2024}, month = feb, doi = {0.1109/CCTA60707.2024.10666540}, }