Averaging Level Control of Multiple Tanks: A Passivity Based Approach

Level control plays a fundamental role in the economic operation of flotation circuits. This paper shows that Interconnection and Damping Assignment Passivity-Based Control, well-known for electrical and mechanical applications, can be used to design high performance averaging level controllers for flotation circuits units using physically motivated mass-balance principles. Using this method we can deal with multiple tanks described by nonlinear dynamics with soft state contraints and rigourously establish the stability of the closed loop system. Furthermore, the transient behavior can be easily regulated selecting the mass storage function assigned to the system. As far as we know, such performance specifications are unattainable with existing methods. The simulation of a three tank flotation circuit illustrates the main issues raised in this paper.