Sampled-Data H-infinity-Control for Time-Varying Hybrid Systems
Artikel i vetenskaplig tidskrift, 2001

This paper presents sampled-data H-infinity-control of linear mixed continuous-time and discrete-time systems, including a mix of continuous-time and discrete-time performance signals and disturbances. However, neither continuous-time control signals nor continuous-time measurements are included. The sampling may well be multirate, i.e. different signals may be sampled by different rates, as long as a periodic pattern is repeated over the period, consisting of a number of sampling steps. In fact, the results are applicable even to arbitrary linear time-varying systems. The sampled-data system is discretised such that the continuous-time performance is reflected in the discretised or "lifted" system. This lifted system is combined with discrete-time updates at the sampling instants to achieve the sampled-data controller. The "hold-states" case is presented as a special application, when there is also a hold circuit at the controller output. The continuous-time Riccati equations with discrete-time updates then can be replaced by one discrete-time static feedback and filter Riccati equation respectively, which also reflect the intersample behaviour. Furthermore, convergence results between the discretised Riccati solutions and the corresponding continuous-time solutions are shown, when the sampling interval decreases towards zero, Simulations are shown when the results are applied to the control of a MIMO jet-engine model.

intersample behaviour


time-varying systems

sampled-data systems

periodic systems

multirate control


Anna-Karin Christiansson

Chalmers, Signaler och system, Reglerteknik och automation

Bengt Lennartson

Chalmers, Signaler och system, Reglerteknik och automation

H.T. Toivonen

Dynamics of Continuous, Discrete and Impulsive Systems Series B: Applications and Algorithms

1492-8760 (ISSN)

Vol. 8 4 427-444


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