Practical Implementation of the Nonlinear Control of the Liquid Level in the Tank of Irregular Shape

In this paper, the control of the liquid level in the tank of irregular (partially conical) shape is considered. The process nonlinearities must be incorporated in the control law to ensure good tracking properties and disturbances rejection despite of the variations of the operating point defined by the desired liquid level. For this purpose, two control strategies are considered: PI+GS (gain scheduling) controller with scheduling function based on the preliminary process identification and B-BAController (Balance-Based Adaptive Controller), which is derived from the nonlinear but significantly simplified model of the process, without any preliminary identification. The control performance of both techniques is verified experimentally and the results show superiority of the latter.