Stability margin optimization via interpolation and conformalmappings

Many interesting problems of robust stabilization can be solved using the complex function theoretic approach of Khargonekar and Tannenbaum (1985). This method is based on the construction of a conformal mapping which reduces the original robust stabilization problem to a Nevanlinna-Pick interpolation problem. The main difficulty of this approach lies in the construction the conformal mapping. The authors present a new numerical algorithm to construct such conformal mappings. Then they demonstrate its effectiveness in the synthesis of optimal gain-phase margin controllers     

On the feasibility of real-time prediction of aircraft carrier motion at sea

Landing aircraft on board carriers is a most delicate phase of flight operations at sea. The ability to predict the aircraft carrier's motion over an interval of several seconds within reasonable error bounds may allow an improvement in touchdown dispersion and reduce the value of the ramp clearance due to a smoother aircraft trajectory. Also, improved information to the landing signal officer should decrease the number of waveoffs substantially. This paper indicates and shows quantitatively that, based upon the power density spectrum data for pitch and heave measured for various ships and sea conditions, the motion can be predicted well for up to 15 s. Moreover, the zero crossover times for both pitch and heave motions can be predicted with impressive accuracy. The predictor was designed on the basis of Kalman's optimum filtering theory (the discrete time case), being compatible with real-time digital computer operation.