Abstract
In many of the design and control problems, it is often felt important for the mathematical model of the process to have more accuracy in its statics than in dynamics.
As to the statics, however, there has been accumulated a great deal of work and it is usually safe to assume that some sort of static model, though often highly nonlinear, is available for most of the processes involved. On the other hand, the effort of process-dynamicists has so far been focussed mainly on obtaining linear models by using perturbation method. The performance of the linear models is naturally poor, especially in the prediction of the static characteristics, when large state changes are involved.
The purpose of the present study is to combine the nonlinear static model with the linear dynamic model and obtain an improved model which describes the process statics exactly and the dynamics approximately for all kinds of inputs.
First, three basic models are proposed. They are so selected that their statics for all inputs and the dynamics for samll inputs are exact. Then techniques to modify or combine these basic models are introduced enabling us to obtain a model with improved dynamic behavior for all kinds of inputs. An example is also shown illustrate the model forming process.
