On IQC approach to the analysis and design of linear systems subject to actuator saturation

• Published in: Systems & control letters Vol. 57; no. 8; pp. 611 - 619
• Main Authors: Fang, Haijun, Lin, Zongli, Rotea, Mario
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2008; Elsevier
• Subjects: Actuator saturation; Applied sciences; Computer science; control theory; systems; Control system analysis; Control system synthesis; Control theory. Systems; Exact sciences and technology; Integral quadratic constraints; Set invariance; Integral quadratic constraints; Actuator saturation; Set invariance; Invariant; Saturation; Feedback regulation; Control synthesis; Non conservative system; Invariant set; Attractor; Integral Quadratic Constraint; Optimization; Linear system; Linear matrix inequality; Domain of attraction; Differential inclusion; Ellipsoid
• ISSN: 0167-6911; 1872-7956
• DOI: 10.1016/j.sysconle.2007.08.016

This paper establishes IQC-based (Integral Quadratic Constraints) conditions under which an ellipsoid is contractively invariant for a single input linear system under a saturated linear feedback law. Based on these set invariance conditions, the determination of the largest such ellipsoid, for use as an estimate of the domain of attraction, can be formulated and solved as an LMI optimization problem. Such an LMI problem can also be readily adapted for the design of the feedback gain that achieves the largest contractively invariant ellipsoid. While the advantages of the proposed IQC approach remain to be explored, it is shown in this paper that the largest contractively invariant ellipsoid determined by this approach is the same as the one determined by the existing approach based on expressing the saturated linear feedback as a linear differential inclusion (LDI), which is known to lead to non-conservative result in determining the largest contractively invariant ellipsoid for single input systems.