Feedforward control of a closed-loop piezoelectric translation stage for atomic force microscope

Area of Science:

• Scanning Probe Microscopy
• Control Systems Engineering
• Materials Science

Background:

• Piezoelectric positioning stages are crucial for high-resolution microscopy.
• Achieving precise and rapid movements is challenging due to inherent system dynamics.
• Phase lag in stage response can degrade image quality and registration.

Purpose of the Study:

• To enhance the effective bandwidth of closed-loop piezoelectric positioning stages.
• To minimize phase lag in stage output for improved image assembly.
• To explore the design of robust feedforward filters for piezoelectric stages.

Main Methods:

• Implementation of simple feedforward control strategies.
• Design of acausal feedforward filters utilizing advance knowledge of control signals.
• Analysis of design constraints for robust feedforward filter performance.

Main Results:

• Achieved a nearly tenfold increase in the effective bandwidth of the positioning stage.
• Demonstrated the ability to achieve near-zero phase lag between input and output signals.
• Showcased how feedforward control improves image registration between left and right scans.

Conclusions:

• Feedforward control is an effective method for significantly improving piezoelectric stage performance.
• Acausal feedforward filters can be employed when control signals are predictable, enhancing dynamic response.
• The proposed feedforward approach is versatile and can be integrated into existing piezoelectric stages.