On-site Measurement of Prototype Hydraulic Machines

 There are two primary measuring techniques that we use to capture 3D geometric data for all types of hydraulic machines :
(a) measurements captured by a portable measurement arm on a gridded surface,
(b) photogrammetry using a series of photographs taken with specialized markers placed on the surface.
Depending on the size and space limitations of the machine, geometric measurements using either method can typically be made in 3-4 days.

Prototype dimensional measurements using a portable measurement arm

To make manual measurements using the FaroArm, first a carefully drawn out grid is created on the machine surface. The dimensions of the grid vary depending on the complexity of the surface. More complicated changes in the surface require higher precision and therefore smaller grid intervals. These measurement points are then analyzed using CATIA 3D modeling software to recreate a digital surface.

Prototype dimensional measurements using photogrammetry

Advances in digital photography have made it possible to measure 3D surfaces with high accuracy. Instead of a grid, carefully placed reflective target markers (pictured on the right) are attached to the machine surface. Each marker has a unique symbol in order to be identified by the 3D capture software. Markers are placed based on the structure and complexity of surface changes, much like the grid system.
Hundreds of photos from various reference points can then be pieced together to create a 3D image of the surface. The technique is particularly advantages in areas too impractical to be reached by the mechanical arm. The camera can take photos at very close range in tight places, such as in between Francis turbine blades on smaller turbines.