Error Analysis and Modeling for an Absolute Capacitive Displacement Measuring System with High Accuracy and Long...

Area of Science:

• Metrology and Measurement Science
• Nanotechnology and Advanced Materials

Background:

• Contact mode capacitive grating displacement systems offer potential for high accuracy and long range.
• Minimizing gap variations is crucial for precise measurements in contact systems.

Purpose of the Study:

• To theoretically analyze factors influencing measurement signals in an absolute capacitive grating displacement system.
• To investigate signal processing methods for improved sensitivity and signal-to-noise ratio (SNR).
• To validate the system's accuracy and potential for nanometer-level displacement measurement.

Main Methods:

• Theoretical analysis of fabrication errors, installation errors, and environmental disturbances.
• Modification of the measurement signal model based on error analysis.
• Development and application of signal processing techniques to enhance signal quality.
• Experimental validation of the theoretical models and system performance.

Main Results:

• The displacement calculation model effectively addresses dead-zone issues using orthogonal signals.
• Fine calculation functions primarily determine model accuracy, with minimal local influence from coarse functions.
• Experimental results demonstrate a displacement resolution of ±4.8 nm and an error of ±34 nm over a 5 mm range.

Conclusions:

• The proposed absolute capacitive grating displacement system shows significant potential for achieving nanometer accuracy over hundreds of millimeters.
• Signal processing and error analysis are key to optimizing the performance of such displacement measuring systems.
• The system's design is robust against amplitude differences, non-orthogonality, and signal offsets, ensuring reliable accuracy.