Asymptotic rejection of unknown sinusoidal disturbances in non-linear dynamic systems with delay

The authors deal with asymptotic rejection of unknown disturbances in non-linear dynamic systems with delay. The disturbances are generated from an unknown linear exosystem whose order is known. The non-linear dynamic system contains non-linear terms in the system state variables with delay. There is no restriction on the non-linear functions, as long as they have continuous first-order derivatives. Here, a state feedback stabilisation control strategy is proposed for the system without the disturbances. An adaptive internal model is then designed and incorporated with the state feedback control design to asymptotically reject the unknown disturbances. A simulation example is included to demonstrate the proposed control design. © 2010 The Institution of Engineering and Technology.