Active disturbance rejection control for nanopositioning: A robust U-model approach.

Area of Science:

• Control Systems Engineering
• Nanotechnology
• Mechatronics

Background:

• Piezoelectric nanopositioning stages suffer from hysteresis, degrading performance.
• Linear active disturbance rejection control (LADRC) offers improved accuracy but has limitations.
• PD controllers in LADRC struggle with uncancelled disturbances and stabilizing high-order systems.

Purpose of the Study:

• To propose a robust U-model active disturbance rejection control (RUADRC) for enhanced piezoelectric nanopositioning.
• To address limitations of LADRC in handling disturbances and system stabilization.
• To improve positioning accuracy, speed, and disturbance rejection capabilities.

Main Methods:

• Incorporation of U-model control and Glover-McFarlane control principles into LADRC.
• Dynamic transformation of the controlled plant to a unit.
• Analysis of closed-loop stability, steady-state tracking error, and phase advantage.

Main Results:

• RUADRC decreases difficulties in stabilizing high-order systems.
• Reduced phase lag and accelerated closed-loop responses were achieved.
• Minimized influence of inaccurate disturbance estimation and imperfect approximation.
• Experimental validation confirmed RUADRC's superiority over LADRC in speed, accuracy, and disturbance rejection.

Conclusions:

• RUADRC offers a more timely and accurate positioning solution for piezoelectric stages.
• The proposed control strategy effectively overcomes hysteresis and improves overall performance.
• RUADRC demonstrates significant advantages for precision motion control applications.