Simulink Control Design™ - MathWorks

Passive Control of Water Tank Level

In this example, you learn how to use Control System Tuner app to design a controller for

a nonlinear plant modeled in Simulink. You accomplish the following tasks:

• Configure the model and app for compensator tuning


• Tune a first-order compensator using passivity-based design


• Simulate the closed-loop nonlinear response.

Simulink Model of the Control System

The watertank_comp_design model, shown in the figure below, models a feedback loop for

regulating the water level in a water tank. The Controller block contains the first-order

compensator to be tuned.

mdl = 'cst_watertank_comp_design';

open_system(mdl);

The Water Tank subsystem models the water-tank dynamics. Water enters the tank from

the top at a rate proportional to the voltage, V, applied to the pump. The water leaves

through an opening in the tank base at a rate that is proportional to the square root of the

water height, H, in the tank. The presence of the square root in the water flow rate makes

the plant nonlinear.

Passive Control of Water Tank Level