This paper presents the current developments of a
novel approach to robust Adaptive Feedforward Control (AFC)
of uncertain linear systems affected by harmonic disturbance of
known frequency. The features that set the proposed method
apart from existing ones are the following: (i) knowledge of
the sign of both the real and imaginary parts of the transfer
function at the frequency of excitation is not needed; (ii) persistence
of excitation is not required; (iii) stability analysis
tools based on averaging are avoided, hence the requirement
of an exponentially stable equilibrium is circumvented. The
methodology reposes upon recent results on adaptive regulation
of uncertain linear systems with weak immersions as well as
on classic tools in adaptive control. A noticeable drawback of
the proposed controller – at this stage of the research – is its
relatively high dimensionality, which stems from the necessity
of a convexification of a non-convex parameter set.
