For a weak nonlinear system the authors obtained sufficient conditions for
locking the solution of a differential equation system of the weak nonlinea
r type within a stable integral manifold, while satisfying the saddle point
conditions of the optimal control evaluation function. The resulting solut
ion can be used as a state feedback solution for the problem of H-infinity
regulator in weak nonlinear systems. By using the P solution of a Riccati m
atrix, sufficient conditions for obtaining the state feedback rule were der
ived from the results of discussion relating to the integral manifold. Then
, the effectiveness of feedback of the weak nonlinear type was confirmed by
simulation in a simple system. In addition, the Lyapunov function was used
to evaluate stability of a closed-loop system obtained based on this feedb
ack rule. (C) 2000 Scripta Technica.