Exercise 3.7 Consider again the distillation process Gs in  The response using the inverse based controller Kinv in  was found to be sensitive to input gain errors We want to see if controller can be modied to yield a more robust system by using the McFarlane Glover H loop shaping procedure To this eect let the shaped plant be Gs GKinv ie W Kinv and design an H controller Ks for the shaped plant see page  and Chapter  such that the overall controller becomes K KinvKs You will nd that min   which indicates good robustness with respect to coprime factor uncertainty but the loop shape is almost unchanged and the system remains sensitive to to input uncertainty