This work introduces a methodology for the minimization, in terms of the l2 norm of the tracking error, of the regulation transients in discrete-time linear systems subject to instantaneous, wide parameter variations. A feedback regulator designed according to the well-known internal model principle guarantees closed-loop asymptotic stability and zero error in the steady-state condition. The compensation scheme for the minimization of transients includes a feedforward action on both the plant and the feedback regulator and a switching policy for the states of the exosystem and of the feedback regulator itself. The feedfoward action and the state switching policy are computed off-line, on the basis of the complete preview of the regulated-sy...