The current methods of measuring screw threads are either time
consuming or expensive. In addition, no single measurement method is
available and capable of accurately measuring all screw thread features
while significantly reducing the measurement time. This paper
introduces a vision system for automatic measurement and inspection of
most types of screw threads. Many image processing and computer
vision algorithms have been developed to analyze the captured images of
screw threads and perform the measurement and inspection processes.
Most of the common screw thread features (18 features) could be
measured by the introduced vision system. The system has been
calibrated for both imperial and metric units and was verified by
measuring a standard ISO metric thread plug gage and comparing the
results of the measurements with the standard values. The results showed
that the maximum difference between the standard and measured values
was ±5.4
m, which provide a good accuracy for measurement.