ASYMPTOTIC REJECTION OF PERIODIC DISTURBANCES WITH ODD-FUNCTION WAVE PATTERNS IN NONLINEAR OUTPUT FEEDBACK SYSTEMS

This paper deals with asymptotic rejection of periodic disturbances whose basic wave patterns can be described by odd functions. This class of disturbances covers asymmetric wave forms in the half period such as sawtooth wave form, as well as disturbances with symmetric half-period wave forms such as sinusoidal disturbances and triangular disturbances etc. The systems considered in this paper can be transformed to the nonlinear output feedback form. The amplitude and phase of the disturbances are unknown. The newly proposed halfperiod integration technique is used to estimate the unknown disturbances in the systems, together with observer design techniques to deal with nonlinearity. The proposed control design with the disturbance estimation asymptotically rejects the unknown disturbance, and ensures the overall stability of the system.