For the design procedure of control system, the method to choose the value of parameters of controller so that the characteristics of the system will pass thle prescribed specification has been generally used, and Root Loci method has been preferred to the design of aircraft controller among many existing design techniques. Such a design method as to derive the closed loop characteristics into the domain of prescribed specifications has a defect that some ambiguity remains in the resulting closed loop system. On the other hand, the notion of optimal control gives us thevery definite design procedure and The PONTRYAGIN's Maximum Principle has contributed much to the design of optimal control system. Although optimal control aims to construct a control system so that some criterion function assumes the minimum value, the strongly damped system usually results from the optimal control technique on the contrary to the expectation of the designer. The reason is such that although the designer has some expectation about the characteristics of the control system to be constructed, he exclusively relies on the result from the optimal control technique without any reference to his expectation. Then the authors has endeavored to solve the optimization problem such that the value of the prescribed criterion function must be the minimum under the constraint that some characteristics of the system to be constructed is given. That kind of problem cannot be solved through Maximum Principle but can be solved only through Parmeter Optimization Method which has been developed by the authors. Parameter optimization technique and the optimal design based on it under the condition that some characteristics of the system to be constructed is prescribed are presented in this paper. How the airplane controller can be designed with satistactory rationality is also presented.
The properties of spectral radiation from weakly ionized argon plasma jet are measured by the spectroscopic method in the arc-heated plasma jet wind tunnel. It is shown that spectral radiation intensity of neutral argon atom decreases as electron temperature increases, and is proportional to electron density cubed and is independent of metastable argon atom density under our experimental conditions. So it is concluded that spectral radiation is caused by three body recombination excitation process (collisional-radiative recombination process).