Asymptotic reconstruction of the Fourier expansion of inputs of linear time-varying systems with applications

Linear time-varying systems driven by periodic input signals are ubiquitous in control systems. For various reasons, including disturbance rejection and diagnosis by analysis of the trajectories, estimation of their input signals is often desirable. In the present paper, we illustrate a recently proposed general method to solve such problems by an asymptotic reconstruction of the Fourier expansion of the unknown input signal along with several examples from the automotive engine industry, and with an oscillating water column retrieving wave energy.