Precision Measurement Method of Large Shaft Diameter Based on Dual Camera System

Area of Science:

• Metrology
• Machine Vision
• Optical Engineering

Background:

• Traditional machine vision methods for shaft diameter measurement face challenges in balancing measurement accuracy and range.
• Existing techniques often struggle to achieve high precision over large measurement scales.

Purpose of the Study:

• To propose and validate a novel large-scale shaft diameter precision measurement method using a dual-camera system.
• To establish a unified world coordinate system for accurate measurements.
• To demonstrate the system's capability in measuring complex components like crankshafts.

Main Methods:

• Development of a dual-camera measurement system.
• Analysis of the dual-camera imaging model to establish a unified world coordinate system.
• Derivation of a measurement formula based on the established coordinate system.
• Experimental validation using calibration plates and a complex crankshaft.

Main Results:

• Calibration tests showed a mean measurement of 100.001 mm with a standard deviation of 0.00039 mm for a 100 mm distance.
• Application to crankshaft diameter measurement yielded mean μ95 values of ±1.07 μm.
• The proposed method's accuracy was found to be comparable to Coordinate Measuring Machines (CMMs), with CMMs achieving ±1.02 μm.

Conclusions:

• The proposed dual-camera measurement system effectively addresses the accuracy-range trade-off in machine vision-based shaft diameter measurement.
• The system achieves high precision, comparable to established methods like CMMs.
• This method offers a viable solution for large-scale, high-accuracy diameter metrology.