Phase leading active disturbance rejection control for a nanopositioning stage

Hysteresis severely reduces positioning accuracy of a piezoelectric nanopositioning system. Inverse hysteresis model-based control is difficult to maintain satisfied performance in presence of uncertainties and disturbances. Linear active disturbance rejection control (LADRC) is a practical approach. However, phase lag of the total disturbance estimation degrades its estimation ability and tracking performance. In this work, a phase-leading extended state observer (PLESO) is constructed by adding a phase-leading network to a linear extended state observer. Advantage of the PLESO on estimating the time-varying total disturbance is analyzed, and influence of the multiplication factor introduced by a PLESO is also discussed. By a leading phase provided by the PLESO, the phase-leading active disturbance rejection control (PLADRC) can compensate the total disturbance timelier, and more satisfied positioning can be guaranteed. Experimental results show that the PLADRC is superior to the LADRC in terms of dynamic responses and disturbance rejection. Without introducing nonlinearities or increasing the order, the PLESO provides an effective way to enhance the active disturbance rejection control (ADRC).