High precision angular displacement measurement based on self-correcting error compensation of three image sensors

Area of Science:

• * Metrology and Measurement Science
• * Optical Engineering
• * Control Systems Engineering

Background:

• * Accurate absolute angular displacement measurement is critical for the performance of numerical control (NC) systems.
• * Existing dual image sensor methods for angular measurement have limitations in eliminating harmonic errors.
• * Harmonic errors in angular displacement measurements can degrade the precision of NC systems.

Purpose of the Study:

• * To develop an image-type angular displacement measurement method with enhanced self-correction error compensation.
• * To analyze the limitations of dual image sensor systems in harmonic error elimination.
• * To achieve higher measurement accuracy compared to existing methods.

Main Methods:

• * Mathematical modeling of harmonic error in angular displacement measurements.
• * Development and implementation of a three-image sensor system for angular measurement.
• * Application of a self-correction error compensation strategy using three image sensors.

Main Results:

• * The proposed three-image sensor method achieved a measurement accuracy of 1.76 arcseconds on a 96 mm circular grating.
• * The dual image sensor method achieved a measurement accuracy of 2.88 arcseconds under the same conditions.
• * The three-image sensor system demonstrated superior harmonic error compensation.

Conclusions:

• * Employing an odd number of image sensors (three) results in higher measurement accuracy than an even number (two).
• * The self-correction error compensation method significantly enhances the precision of angular displacement measurements.
• * This research provides a foundation for high-precision image-based angular displacement measurement systems.