On l(p) disturbance rejection using periodic feedback control

In this paper, the performance of discrete time periodically time-varying c ontrollers for rejection of I, specific and uniform disturbances is analyze d. For control of linear time-invariant plants, this paper distinguishes li near time-invariant controllers from linear non-time-invariant periodic con trollers in the performance analysis. For a given linear non-time-invariant periodic controller, a linear time-invariant controller is constructed and necessary and sufficient conditions are presented under which the linear t ime-invariant controller gives strictly better I, control than the non-time -invariant periodic controller. (C) 1999 Elsevier Science B.V. All rights r eserved.