ON THE APPROXIMATION OF NON-PROPER CONTROL LAWS

In this paper we propose a way to approximate a non-proper stabilizing control law for a proper system by using a sequence of proper control laws which guarantee stability. This is done by introducing a positiv e real parameter, epsilon such that when it tends to zero the proper a pproximation tends to the non-proper control law. This work is motivat ed by some of our previous results concerning the use of 'derivators' for solving some control problems and considers the approximation sche mes that are deduced for the corresponding derivative actions. An illu strative example (for disturbance rejection) is given.