Video Gauge

A Video Gauge system comprises a PC with the sophisticated Video Gauge software installed together with the following:

• One or more high-resolution digital video cameras
• Appropriate lenses for the application
• Voltage input/output module
• Lighting
• Tripod
• Rugged case for storage and transportation including spray-paints for applying speckle patterns.

How it works

The high-resolution digital camera monitors the object under test. By fitting an appropriate lens the Video Gauge will measure objects smaller than 1mm to larger than 100m.

The Video Gauge utilises Imetrum’s patented technology to precisely measure the 2D position of targets in images from the video camera. Special targets are not required, for example, any of the following may be used:

• Natural features such as bolt heads
• ‘blob’ drawn with a marker pen
• ‘speckle pattern’ applied with spray paint

The user identifies these targets to the system simply by using the mouse to drag a bounding box around them. The system then precisely measures the position of each target in every image from the video camera. Up to 100 targets can be measured in real-time at 15Hz. From the measured positions of these targets, the system calculates:

• Displacement, velocity, acceleration
• Distance
• Angular rotation
• Material properties
  • 2D Strain (tensile, compression, shear)
  • Poisson’s ratio
  • Stress/strain curve
  • Modulus

Accuracy

The accuracy of the system has been measured for both displacement and strain.

Displacement

To measure displacement accuracy, the Video Gauge outputs were compared to a calibrated Digital Test Indicator (DTI) for a simple displacement. The outputs of the two devices were identical to within 0.1%.

The test was carried out independently by Airbus. Full details can be found in this case study.

Strain

To measure strain accuracy the Video Gauge outputs were compared to a calibrated strain gauge. The measurements were made on a high-grade aluminium dog-bone specimen undergoing a tensile test. The Video Gauge results were identical to the strain gauge to within 0.5%. The Video Gauge was also used to measure the Poisson's ratio which came out as 0.33 as expected.

Full details can be found in this case study.

Options and Specifications

Details of the various system options and their specifications can be found here.