Robust stabilisation of chemical reactors

The design of stabilising feedback control laws for unstable chemical reactors has been studied extensively. There are nevertheless important theoretical questions that are still open. One of them, which is the main concern of this paper, is the design of feedback control laws that are globally stabilising, robust against kinetic uncertainties and robust against control input saturations. In this paper, for a general class of continuous stirred tank reactors, we propose a set of controllers that guarantee the global temperature stabilisation in spite of strong uncertainties on the dependance of the kinetic functions with respect to the temperature. A main feature of these controllers lies on their capability of handling input constraints in some instances. Moreover, if the reactor is globally asymptotically stable in isothermal condition, then our results turn into global stabilisation of both temperature and concentrations. (Here, we point out that in spite of the global asymptotic stability in isothermal condition, the overall dynamics of the open loop reactor can be unstable). The design is based on I/O state feedback linearisation with an appropriate dynamic extension.