Observer-based robust controller design and realization of a gantry stage

A precise positioning operation is typically required for gantry systems in applications such as drop-on-demand (DOD) printing processes, precision metrology, and circuit assembly. This work presents experimental results from studies of a disturbance observer (DOB) based variable structure controller (VSC) for a gantry stage. For DOB-based controllers, a nominal model is needed; however, obtaining the nominal model is difficult for systems with friction. A pseudo-random binary signal (PRBS) is utilized to identify the linear nominal model of the gantry stage with friction. To compensate for friction effects, a filtered-VSC is studied to increase robustness and compensate for modeling uncertainties and external disturbances. Experimental results demonstrate the effectiveness of the proposed robust control structure.

Research highlights
► A disturbance observer (DOB) based variable structure controller (VSC) is studied in this work.
► To obtain the nominal model of the DOB -based controller, a pseudo-random binary signal (PRBS) is utilized to identify the linear nominal model.
► To compensate for friction effect, a filtered -VSC is studied to increase the robustness and reject the external disturbance.