Experimental validation of a nonlinear backstepping liquid level controller for a state coupled two tank system

This paper addresses the nonlinear control design problem for a state-coupled, two-tank, liquid level system. Motivated by a desire to provide precise liquid level control, a set of nonlinear backstepping techniques is developed for the state-coupled, two-tank, liquid level system dynamics. Specifically, a model-based backstepping controller and an adaptive backstepping controller are designed for the two-tank, liquid level system. Utilizing the Lyapunov machinery, the set of backstepping control schemes is proven to yield exponentially/asymptotically stable tracking response for trajectories that are continuous and have bounded derivatives up to second order. To show the efficacy of the adaptive backstepping control design, detailed experimental comparisons vis-a-vis a proportional plus integral controller are provided.