Design of rate and amplitude saturation compensators using three degrees of freedom controllers

This paper proposes two frequency-domain design techniques for rate and amp litude saturation compensators formulated as three degrees of freedom contr ollers. For single constraint systems, it shows an equivalence between the a posteriori compensator design and the a priori controller synthesis propo sed by Horowitz. For rate and amplitude constrained systems, the three degr ees of freedom controller is a special case of the general saturation compe nsator. Through multivariable frequency domain analysis of the compensators , hidden properties of the three degrees of freedom controller are revealed . These inherent properties are utilized in compensator designs by techniqu es shaping the characteristic loci and specification of singular values. Si mulated examples illustrate the success of the design methods.