Between a recent static detonation and an upcoming test evolution, a decommissioned frigate takes hits to help the Navy test a new use of lidar scanning and 3D ship models, assessing battle damage.
The static detonation training event at the end of March, during which an explosive charge was placed on board the ship with the aim of damaging it, and the evolution to come are essential elements of a megaproject focused on the lidar funded by the Naval Innovative Science and Engineering (NISE) program. As part of the project, several warfare centers are working together to build 3D models of entire ships from lidar scans, with the aim of expanding the use of these models for combat damage assessment and repair, as well as for installation and retrofitting, and other fleet applications.
“These training events with the decommissioned vessel are very good opportunities for the lidar megaproject,” said Patrick Violante, team leader of the Advanced Data Acquisition, Prototyping Technologies and Virtual Environments Laboratory at Naval Surface. Warfare Center (NSWC), Philadelphia Division (PD), one of the megaproject partners. “We want to show that we can quickly capture damage, overlay it on the reference model, document the condition accurately, and then share the data with the wider community to make engineering decisions.”
This effort comes at a time when the options and affordability of lidar analysis tools are increasing. By harnessing the technology to build more 3D ship models, the lidar megaproject partners aim to reduce the need for engineering teams to visit ships, enable more remote assistance, such as virtual checks of vessels, and to shorten response times to casualties and maintenance issues encountered by the fleet. at sea.
“You can’t send the ship to people, but you can send the 3D model to people,” said Ken Nahshon, a research engineer who focuses on weapon effects damage at NSWC Carderock Division (CD) in West Bethesda, Maryland, another megaproject partner.
Lidar, short for light detection and ranging, scans an object in three dimensions by bouncing laser beams off it and measuring the time it takes to return. The technology can capture a large network, or cloud, of data points and stitch scans together from different perspectives to create a millimeter-accurate 3D digital representation of the object. The latest lidar analysis tools can also take photos and overlay them on the data point cloud for a more realistic model.
These lidar-generated 3D models have become a priority for the Navy fleet. Last year, the Integrated Warfare Systems Program Executive Office issued a memo directing installation and modernization teams to perform lidar scans, when the technology is available, of the areas they are working on aboard ships of Marine.
“Program offices are actually asking for lidar analyzes now, which is really important,” said Jason Bickford, research director at NSWC Port Hueneme Division (PHD), another megaproject partner. “The technological transition to support the fleet must be our top priority. We can play with technology all day, but unless we can align technology with a gap in the fleet or the requirements of the program office, it’s very difficult to have an impact on our research; it’s just playing.
To this end, NSWC PHD, NSWC PD and NSWC CD have secured funding from NISE for a war center collaboration known as the Mega Project.
“These are the larger, bolder projects that require headquarters approval and support, and which a warfare center might not be able to take on on its own,” Bickford said. .
Rationalization of facilities
For several years, the NSWC PHD has been brainstorming with other In-Service Engineering Agent of the Future campaign partners, including Violante at the NSWC PD and Ray Provost, Project Manager for the Reverse Engineering, Science and Technology Lab. for Obsolescence, Restoration and Evaluation, known as the RESTORE Lab, at the Naval Information Warfare Center (NIWC) Pacific in San Diego, on the potential of lidar scanning to streamline their installation and retrofit work .
For example, more accurate installation drawings could help avoid unforeseen obstacles and delays during work on the vessel. Lidar scans can produce millimeter-accurate 3D models of ships. Installation and modernization teams can use these models to measure areas of the vessel before boarding to install equipment.
“In this (digital) environment, we can take precise measurements between components; we can determine the distances between the partitions and the equipment; we can make sure doors and cabinets can open properly,” Bickford said. “We are looking for items that could interfere with our installation, which we need to move or plan.”
Since different war centers work on different areas of a ship, Violante and Bickford felt it was necessary to scan the whole ship rather than specific areas. They began to strategize on how to build a collective of stakeholders from all war centers that would combine their efforts.
“Rather than the Port Hueneme division just scanning the radar spaces and the combat spaces, then scanning the Philadelphia hull, the mechanical and electrical spaces, what if we scan the entire ship?” said Bickford. “We could merge our datasets for a larger, more accurate and more comprehensive ship-level model. It was the original pitch.
Full vessel analysis
In 2020, this pitch came into practice as NSWC PHD worked with NIWC Pacific to lidar scan the entire interior and exterior of USS San Diego (LPD 22), an amphibious transport dock. The result was the first complete 3D digital model of an LPD-class ship.
Scanning an entire vessel can seem expensive due to the extensive data capture and analysis involved. For example, the team that scanned the USS San Diego captured more than 7,000 individual scans from various positions in and around the massive ship over nearly two months. But Bickford said ship-level scans are a worthwhile investment given the potential to improve efficiency and eliminate costly errors.
“When you’re looking at an overhaul that will cost the Navy millions of dollars, (the cost of lidar scanning is) pennies as you improve planning and installation times, fix any issues, and make sure that the ship gets out of the shipyard faster,” he said. “There’s a huge return on investment.”
The value of the full ship sweep increases further by expanding its use among the various war centers. In other words, the more stakeholders using the dataset, the lower the cost per user.
Broaden the scope
Although Violante and Bickford initially focused on the role of lidar scanning in installation and modernization, they eventually found other potential uses and communities that could benefit from ship-level 3D models, such as damage assessment.
“Carderock Technical Areas cover structural damage caused by weapon attacks, collisions, corrosion or exceeding operational loads,” Nahshon said. “For us, the data provided by 3D scanning is really valuable.”
If a Navy vessel sustains damage during an engagement, Naval Sea Systems Command is generally responsible for engineering assessments to determine whether the vessel should return home or remain in combat. Historically, this required people to go to the ship to inspect the damage, take photos and write a report. To respond to casualties more efficiently and accurately, Nahshon saw the potential of using a “healthy” pre-crash 3D model of a vessel to compare to its damaged state.
Nahshon considered using unmanned aircraft systems (UAS), also known as drones, which are already in theater to capture photos and video of damaged areas on ships. In a type of 3D scanning known as photogrammetry, images from a UAS could be stitched together to create a 3D representation of the damaged area. This new model could then be compared to the healthy pre-damaged model from the lidar scanner for a more accurate damage assessment.
The upcoming evolution of the decommissioned frigate will test Nahshon’s idea of generating 3D datasets using aerial imagery.
First, the megaproject partners built a pre-crash reference model of the frigate. At a Philadelphia shipyard in mid-February, personnel from NSWC PHD, NSWC PD and NIWC Pacific scanned the vessel with a tripod-mounted 3D laser scanner.
The resulting model is a very accurate and up-to-date representation of the inactive frigate, both inside and out. After the ship sustains damage in the upcoming test evolution, a drone and manned aerial platforms will take photos to build a post-accident model. Next, a team from NIWC Pacific will overlay the post-crash model over the pre-crash model for damage assessment purposes.
“If successful, this will both demonstrate the value of 3D scanning technology for combat damage assessment and repair, and assess the ability of operational UAS assets already in theater to fulfill the critical scanning role. “Bickford said.
Another similar static detonation and subsequent test evolution, these at a disused amphibious transport dock, are scheduled to take place this summer in Hawaii as part of Exercise Rim of the Pacific 2022. Provost said a team would travel to Hawaii ahead of time to scan the ship and build a pre-crash 3D model. As with the decommissioned frigate, the team will compare post-crash scans of the amphibious transport dock to the sound model to assess the structural impact.
Beyond efforts around static detonations and test evolutions, the lidar megaproject partners meet every two weeks and held a workshop last fall to discuss scanning standards, data storage, files, classification and other key topics.
“One of the questions we’re working on is ‘What’s the best tool for the job?'” Violante said. “There are several types of lidar technology, from drones to tripod scanning. We seek to choose the right tool depending on the scenario or the size of the space.
Nahshon said with so many applications for lidar and so many people across the Navy interested in using it, the megaproject brings cohesion and avoids duplication of effort.
“Lidar is an enabling technology, and many people are working with it in different warfare centers,” Nahshon said. “Now we’re all connected, and that’s great.”