LQG-Based Real-Time Scheduling and Control Codesign
Författare
Summary, in English
In the thesis, four linear-quadratic-Gaussian (LQG) codesign methods are proposed: stochastic, periodic, harmonic, and robust LQG codesign. In stochastic LQG codesign, the delay distributions are calculated at design-time. Then LQG controllers are designed assuming these delay distributions. The obtained task periods generally give rise to infinite hyperperiods. This can be avoided by perturbing the periods slightly in order to obtain a finite hyperperiod, yielding a periodic delay pattern for the control loops. The periodicity is then accounted for by using periodic LQG control design, resulting in a periodic sequence of feedback gains for each controller. In harmonic LQG codesign, again the task periods are perturbed, but this time to make the periods harmonic. The scheduling-induced delays will be constant and standard LQG design can be applied. Finally, a robust LQG codesign method is presented. The design is based on convex optimization and guarantees system robustness in the presence of delay and jitter. A new rule of thumb for initial sampling period assignment is proposed. We propose a jitter-aware priority and period assignment codesign method to optimize the overall system performance.
A large evaluation of the proposed four codesign methods is performed using the Jitterbug toolbox. All of the four methods lead to improved control performance compared to earlier work. The harmonic scheduling and control codesign shows the largest overall improvements.
Avdelning/ar
Publiceringsår
2017-11-20
Språk
Engelska
Publikation/Tidskrift/Serie
PhD Thesis TFRT-1119
Fulltext
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Dokumenttyp
Doktorsavhandling
Förlag
Department of Automatic Control, Lund Institute of Technology, Lund University
Ämne
- Control Engineering
Nyckelord
- LQG control
- Real-time system
- Scheduling
- Time-delay system
Status
Published
Projekt
- Co-design of Networked Embedded Control Systems
- ELLIIT LU P02: Co-Design of Robust and Secure Networked Embedded Control Systems
Forskningsgrupp
- LCCC
Handledare
ISBN/ISSN/Övrigt
- ISSN: 0280-5316
- ISBN: 978-91-7753-516-4
- ISBN: 978-91-7753-515-7
Försvarsdatum
15 december 2017
Försvarstid
10:15
Försvarsplats
Lecture hall M:B, building M, Ole Römers väg 1, Lund University, Faculty of Engineering LTH, Lund
Opponent
- Arben Cela (Professor)