Limitations imposed by RHP zeros/poles in multivariable systems

This paper examines the limitations imposed by Right Half Plane (Rhp) zeros and poles in multivariable feedback systems. The main result is to provide lower bounds on || WXV(s) ||_∞ where X is S, S_I, T or T_I (sensitivity and complementary sensitivity). Previously derived lower bounds on the H_∞-norm of S and T are thus generalized to the case with matrix-valued weights, including bounds for reference tracking and disturbance rejection. Furthermore, new bounds which quantify the minimum input usage for stabilization in the presence of measurement noise and disturbances are derived.