High Accuracy Inspection
2G Robotics Underwater Laser Scanner produces 3D models of a Top Tendon Connector (TTC) with millimetric accuracy
In September 2017, 2G Robotics arranged a demonstration of the efficacy of underwater laser scanning for as-built surveys. Traditional as-built surveys are often conducted by divers capturing essential measurements by hand-held calipers. This method is time-consuming, can negatively affect personnel safety, and has a higher potential of inaccuracies due to human error. The objective of the demonstration was to quantify the accuracy of underwater scanning by completing an inspection of a Top Tendon Connector (TTC) .
2G Robotics’ mid-range underwater laser scanner, the ULS-200, was used in the demonstration. The system was mounted 42 cm above the target, a Top Tendon Connector, with a bespoke deployment frame. For each of the six slips, the system was positioned between the two relevant slip pins, directly above the target slip, to capture all surfaces of the target. Each slip was scanned in approximately 1.5 minutes with the repositioning of the system and frame taking approximately 3.5 minutes resulting in a total survey time of 30 minutes.
The data point clouds generated from laser scanning were then cleaned of extraneous data/noise and fitted with 3D surfaces via solidworks. The results of measurements taken from solidworks are in found in the table below.
Scans of the Top Tendon Connector’s six slips were completed in 30 minutes. On average, the measurements generated from the 3D laser data were accurate within one millimeter (0.04inches). The results of the project highlighted the following key benefits of underwater laser scanning:
Improved Operational Efficiency
Less time in the field drives down costs and allows personnel to spend more time on critical analysis
High-resolution 3D models reveal fine-scale measurable features not captured by other methods
Accurate to the Millimetre
Millimetric accuracy enables personnel to make better-informed decisions
Equipped for the Future
The 3D model serves as an As-Built model of the subsea asset to provide a baseline for future intervention work