Abstract: An optimal control system is described having multiple aspects. In one aspect, an arrangement is provided for eliminating integrator windup. This aspect includes forming a control difference signal that is a combination of differenced inputs and then subsequently integrating and limiting the control difference signal to form a control signal that is provided to the plant. In another aspect, an arrangement is provided for eliminating cross-channel coupling. In this aspect, an error signal is formed as the difference between a commanded signal and a regulator sensor signal. In addition, an injection error signal is combined with the error signal. The injection error is of an amount sufficient to ensure that only an attainable command signal is provided to the plant, without significant cross-channel coupling due to saturation of a control effector. In another aspect, an arrangement is provided for improving output mixing of the control signal between available plant effectors.