Robust control of a rotational system via on-line inertia identification

The present work deals with the simultaneous control and identification of a rotational mechanical system constituted by a tandem connection of disks and rotational springs. We consider the rotational system to be controlled as constituted by the first disk alone. This is to be modeled by a simple second order controlled dynamics affected by unknown perturbations arising from the cascade attachment of similar disks and springs in an unknown quantity and of unknown inertia values. The only involved parameter in the robust perturbation rejection controller design is, then, the moment of inertia of the first disk, which is also assumed to be unknown. The on-line disk inertia identification process is carried out using the recently introduced algebraic identification technique. The online identification is achieved using exponential modulation functions, instead of the traditional convolutions with suitable powers of the time variable. The control law is a robust generalized proportional integral controller which regards the unknown part of the dynamics as a locally bounded, self updating, polynomial perturbation. The feasibility of this scheme is shown through numerical simulations as well as laboratory experimental results.