Choosing a Proper Control Structure for a Mechatronic System with Variable Parameters

The paper presents design methods and control structure solutions dedicated to servo systems with continuously variable parameters. In order to obtain high control performance for the strip winding system – speed control – four cascade control structures (CCS) (with a inner proportional-integral (PI) current controller) with bump-less switching between several control algorithms are developed and tested. These solutions prove simplicity in adaptation on the representative operating points. The current controller is tuned on the basis of the Modulus Optimum method (MO-m). The basic speed controllers are tuned by the Extended Symmetrical Optimum method (ESO-m) and the developed continuous-time speed controllers are discretized using Tustin's method. The developed speed controllers are: (1) a classical PI controller, (2) a Takagi-Sugeno PI fuzzy controllers (TS-PI-FCs), (3) a two-degree-of-freedom PID (2-DOF PID) and (4) a sliding mode (SM) PI quasi relay control solution. The cost-effective feature is ensured by simple controller design and easy implementation, and it is illustrated by a case study which includes simulation results. A process with variable inertia, variable reference and load disturbance is discussed due to its applicability as a controlled plant in the field of mechatronic systems.