Abstract
As a practical application of optimal tracking control theory, the problem of sub-optimal control system locally utilizing the future values of the dynamic characteristics and the desired function is studied in the case of a linear time-variant system with a quadratic criterion.
The optimality of the sub-optimal tracking control system is examined and is expressed in simple inequalities. These inequalities show that the sub-optimal values of feedback gain, control input and criterion settle down to their optimal ones in exponential order of the eigenvalues related to the closed-loop system.
As the results, the sub-optimal control system which utilizes the local future values of the dynamic characteristcs and the desired function in the time interval related to the so-called time lag accompanied with the constructed feedback system at every moment gives almost the same control as the globally optimal control in a practical sense.
The simple inequalities obtained in this paper are also used to determine the reasonable local interval of the dynamic characteristics and the desired function to be utilized and to estimate the optimality of the sub-optimal control system to be realized.
