Emphasizing an Expanded Optimal Control Policy for a Coupled Tanks System with Random Disturbance

A coupled tanks system, which consists of a joint of two tanks together through pipes in order to reserve water
at the operating height level, is an important study in the control engineering and process industries. In this
paper, an expanded optimal control policy is proposed to study the coupled tanks system, where the random
disturbance is added into the system. Since the dynamics of the coupled tanks system can be formulated as a
nonlinear system, determination of the optimal water level in the tanks is useful for the operation decision. On
this point of view, the coupled tanks system dynamics is usually linearized to give the steady state operating
height. In our approach, a model-based optimal control problem, which is adding with adjusted parameters, is
considered to obtain the true operating height of the real coupled tanks system. During the computation
procedure, the differences between the real plant and the model used are measured repeatedly, where the
optimal solution of the model used is updated. On this basis, system optimization and parameter estimation are
integrated. At the end of the iteration, the iterative solution approximates to the correct optimal solution of the
original optimal control problem, in spite of model-reality differences. In conclusion, the efficiency of the
approach proposed is shown. Optimal solution of the coupled tanks system with random disturbance could be
further improved by using the filtering techniques. Therefore, it is suggested to determine the optimal filtering
solution of the coupled tanks system with the random disturbance in future research.