Safe estimate of sinusoidal signals for control applications

Second order notch filters are commonly used for frequency estimation purposes. They are characterised by a single design parameter, the value of which is selected to achieve a suitable compromise between tracking performance and bias/variance errors. Funnel filters are a recently proposed class of fourth order filters, which provide enhanced tracking capability, without any deterioration of the steady-state performance. In this paper an application example is proposed: notch and funnel filters are used for the estimation of the rotating speed of a DVD player, in order to implement a control scheme which selectively cancels narrow-band disturbances