In this paper the complex system is divided into reduced order subsystems with different time scales according to the singular perturbation theory and the method of the variable structure control, and the controller in each subsystem using sub-optimal control algorithm of second order sliding mode which can eliminate the chattering is designed.

On the basis of one-fourth automobile suspension, a nonlinear model is built for electromagnetic active suspension and a sub-optimal controller is designed by applying modern control theory.

In order to simplify the calculation and implementation of controllers, a sub-optimal control design method based on model reduction techniques is proposed in this paper.

Using developed optimal model for Ring-Pull Can size design,the optimal solution of cylindric can size design and the suboptimal solution of frustum of a cone on cylinder as well as CCB-1A can size design are botained.

The size design of optimal model for Two pieces Aluminium Can has been established,two kinds of suboptimal solution about the model has been discussed.

In this paper The suboptimal solution of the synthesis of static_state feedback control under partial observation is given by using maximal network flows of graph theory.

Then three numerical methods are discussed: neighboring optimal feedback strategy, iterative correction method and continuous iterative correction method.