Measurement Method of Fuel Nozzle Cone Angle Based on Point Cloud Slicing

Area of Science:

• Mechanical Engineering
• Metrology
• Computational Geometry

Background:

• Traditional fuel nozzle dimensional measurement methods suffer from low efficiency and high error rates.
• Accurate measurement of inner hole cone angles is critical for fuel nozzle performance.

Purpose of the Study:

• To develop a high-precision, robust method for measuring the inner hole cone angle of fuel nozzles.
• To improve upon existing circle fitting algorithms for dimensional metrology.

Main Methods:

• Utilized shape-from-focus to extract 3D point clouds of fuel nozzle inner holes.
• Developed an optimized RANSAC algorithm with region constraints for circle fitting on projected 2D slices.
• Compared the proposed region-constrained RANSAC (RC-RANSAC) against least squares and standard RANSAC using quantitative metrics (σ, RMSE, ε).

Main Results:

• The proposed RC-RANSAC method demonstrated superior performance with σ = 2.826 px, RMSE = 2.826 px, and ε = 95.2%.
• Achieved a cone angle measurement deviation of only 1.0°, closely matching Keyence measurements (0.8° error).

Conclusions:

• The region-constrained RC-RANSAC method offers a significant advancement for accurate and robust cone angle measurement in fuel nozzles.
• This technique provides a valuable new approach for precision metrology in engineering applications.