NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
A methodology for the synthesis of robust feedback systemsA new methodology is developed for the synthesis of linear, time-variant (LTI) controllers for multivariable LTI systems. The resulting closed-loop system is nominally stable and exhibits a known level of performance. In addition, robustness of the feedback system is guaranteed, i.e., stability and performance are retained in the presence of multiple unstructured uncertainty blocks located at various points in the feedback loop. The design technique is referred to as the Causality Recovery Methodology (CRM). The CRM relies on the Youla parameterization of all stabilizing compensators to ensure nominal stability of the feedback system. A frequency-domain inequality in terms of the structured singular value mu defines the robustness specification. The optimal compensator, with respect to the mu condition, is shown to be noncausal in general. The aim of the CRM is to find a stable, causal transfer function matrix that approximates the robustness characteristics of the optimal solution. The CRM, via a series of infinite-dimensional convex programs, produces a closed-loop system whose performance robustness is at least as good as that of any initial design. The algorithm is approximated by a finite dimensional process for the purposes of implementation. Two numerical examples confirm the potential viability of the CRM concept; however, the robustness improvement comes at the expense of increased computational burden and compensator complexity.
Document ID
19880007958
Acquisition Source
Legacy CDMS
Document Type
Thesis/Dissertation
Authors
Milich, David Albert
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 5, 2013
Publication Date
March 1, 1988
Subject Category
Cybernetics
Report/Patent Number
NAS 1.26:182455
NASA-CR-182455
LIDS-TH-1748
Accession Number
88N17342
Funding Number(s)
CONTRACT_GRANT: NAG2-297
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available