An adaptive tracking problem with a control input constraint

Abstract In this paper we consider the problem of controlling an uncertain linear time-invariant (LTI) continuous-time plant when there is a control input constraint. A switching controller is presented which will carry out asymptotic error regulation for constant reference and constant disturbance signals which are compatible with the control input constraint, assuming that (i) the plant is asymptotically stable, (ii) the plant has no transmission zeros at zero, and (iii) the plant has as many inputs as outputs. This controller is quite easy to implement, especially in the single-input-single-output (SISO) case, and is noise tolerant. Some examples, including a model of a three-input/three-output distillation column, are included to illustrate the controller behaviour.