How is it guaranteed that ROBSTAB finds the worst-case stability margin over the complete frequency range without gridding?
1 view (last 30 days)
Show older comments
MathWorks Support Team
on 7 Oct 2019
Answered: MathWorks Support Team
on 31 Dec 2020
How is it guaranteed that ROBSTAB finds the worst-case stability margin over the complete frequency range without grinding? Can you provide the principle of the underlying algorithm/method or a source? Can you also provide information on which approach is used to calculate the lower and upper bound on Mu?
Accepted Answer
MathWorks Support Team
on 7 Oct 2019
Before MATLAB R2016b, Mu calculations were done on frequency grids. While it was fine for complex uncertainty, this was prone to miss peaks and discontinuities in the presence of uncertain real parameters, often leading to over-optimistic stability margins.
Starting in MATLAB R2016b, functions like ROBSTAB, ROBGAIN, and WCGAIN use a modified algorithm that eliminates this issue. The main change is in the Mu upper bound computation, which seeks to certify entire intervals rather than just individual frequencies and to cover the entire frequency axis with such interval certificates. This is how we obtain a guarantee over the entire frequency range.
0 Comments
More Answers (0)
See Also
Categories
Find more on Robustness and Worst-Case Analysis in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!