Touching History With Underwater Robotics
One of the biggest challenges of robotic archeology—being able to manipulate fragile objects without breaking them. The hand with three fingers called "adaptive grasp" adjusts to the shape of the object that it grips without breaking it. Photo credit: Teddy Seguin/FrÈdÈric Osada—DRASSM/mages Explorations.
The lure of pirates and buried treasure has long inspired generations of explorers to dive deep into the ocean's depths. Shielded from the world above, the remains of about three million shipwrecks lay hidden on the cold, dark seafloor around the world. The future of underwater archaeology is moving from the shallows into the deep ocean at over 90 m down where the harsh conditions have preserved thousands of elusive wrecks. Now, the French Department for Underwater Archaeology (DRASSM) and the French Montpellier Laboratory of Computer Science, Robotics, and Microelectronics (LIRMM) have found a way to gain access to previously inaccessible historical sites by developing pioneering underwater robotics for deep-sea archaeology. Underwater archaeologists for the first time can “feel” ancient artefacts up to 2,000 m below through the touch of a robot.
Since 2013, the Corsaire Concept Project aims to develop new tools for deep underwater archaeology at depths from 50 to 2,000 m. While the project is led by the DRASSM, the LIRMM coordinates the robotics division. Transforming the future of underwater archaeology into a robotic concept are several laboratories, including P’Prime; Stanford Robotics and Onera; and SME, Techno Concept, who have proposed new robotic tools under the supervision of expert archaeologists. Furthermore, the new robotic systems are tested in one of the most important sites in maritime history—the Moon.
Discovered by a submarine in 1993, the Lune (the Moon), lies 90 m under the surface. In November 1664, the warship of Louis XIV was wrecked off the French coast of Toulon, taking nearly one thousand people with her into the sea. Since 2012, the site has been a test laboratory for innovation in underwater archaeology and the advancement of robotics.
The Speedy submarine robot is connected to the ship by an umbilical that ensures its power supply and information exchanges with the researchers. Photo credit: Teddy Seguin/FrÈdÈric Osada—DRASSM/mages Explorations.
Dr. Vincent Creuze, the scientific coordinator of the Corsaire Concept project (LIRMM), explains: “Wrecks located at great depths, such as the Lune, tend to be far better preserved. Apart from the act of sinking, these ships are generally sheltered from human or environmental disturbance such as ground swell, backwash, and tidal movements. But, because of the dark and high-pressured environment, it is also extremely difficult for humans to gain access.”
“The difference between conventional underwater archaeology and deep-sea marine archaeology is, of course, depth. The latter requires investigative resources on an entirely different scale, which is still very largely experimental. Underwater 2D and 3D photogrammetry have become very common in the last five years and are now widely used for underwater archaeology, either with ROVs or AUVs. But, the navigation and control capacities of the robot near 3D structures still need to be improved.”
For the last few years, several laboratories and companies have started to work on “path planning” and “path following” to make underwater photogrammetry more efficient.
Standard underwater manipulator arms are used to sample ancient artefacts from the deep. But, such operations are very long and require the robot to “land” on the seabed to provide a stable basis for the manipulator—not without risk of damaging buried objects under the vehicle. Moreover, the claws of underwater manipulator arms are not very well suited to fragile archaeological artefacts.
The robotic hand is operated dry from the ship's scientific command post where the live images of the on-board cameras arrive. Photo credit: Teddy Seguin/FrÈdÈric Osada—DRASSM/mages Explorations.
Under the leadership of Vincent Creuze, the LIRMM has developed a prototype of an archaeological robot. As part of this research, the first Speedy robot tested an omnidirectional vision system and an anthropomorphic hand with three fingers that follow the shape of the objects seized. To mimic the gentle touch of human archaeologists, the robotic hand is equipped with a pressure sensor and “adaptive grasp” that allows it to adjust to the shape of the object it handles without breaking it.
“The main challenge is to design robots that can be directly piloted by an archaeologist and provide the pilot the sense of touch. We are developing underwater robotic hands to do just that. This work is in collaboration with the PPRIME Institute within the SEAHAND Project, founded by the French Research Agency (ANR). The first tested robotic hand itself was made by Techno Concept in collaboration with the LIRMM and the DRASSM. We also work on the monitoring of archaeological sites and on localization and navigation for 3D modeling with the ONERA French Research Institute,” said Creuze.
Most of the tests so far are conducted on the Lune shipwreck testing laboratory. Some other experiments have been carried out on deeper antic shipwrecks (500 m) and on a more modern battleship wrecked in 1917, located 1,025 m deep.
With the hand and the Speedy ROV, we have collected numerous fragile artefacts from the Lune site without any damage. The DRASSM have also tested many types of robotics devices such as large claws, water jetting, crawlers, several types of lights, and several custom-made cameras. The robots need to be pressure resistant, which means that most moving mechanical parts are oil filled. And of course, they operate in the dark so need powerful lights.”
Each campaign gives the opportunity for Creuze and his team to experiment and improve new tools that are developed by the LIRMM and by the companies and institutions participating in the Corsaire Concept Project.
At the centre of the operation, there was the DRASSM's underwater research vessel, the André Malraux. Considered “the jewel in the crown” of marine archaeology, it is specially designed to dispatch machines to locations beyond the range of human divers.
Creuze explains, “The most well-preserved shipwrecks are located very deep, away from many environmental threats, away from looters, and under very stable environmental conditions. These shipwrecks cannot be excavated without robots. But now fishing activities threaten these deep wrecks, such as deep-sea trawling, and are no longer completely protected.”
The robotized hand can be replaced by claws, kinds of rakes that crisscross to pick up objects difficult to grab. Photo credit: Teddy Seguin/FrÈdÈric Osada—DRASSM/mages Explorations.
The samples are then deposited in a box which will be brought up to the surface - Speedy the robot can thus return to work without delay. Photo credit: Teddy Seguin/FrÈdÈric Osada—DRASSM/mages Explorations.
“But, thanks to pioneering work in underwater robotics, I’m very excited for the future. We have the great chance to collaborate with Stanford Robotics Laboratory. Professor Oussama Khatib's team has developed the amazing 'Ocean One' humanoid diver. This robot made its first dive in April 2016 in France and demonstrated incredibly promising abilities for underwater archaeology.”
The Ocean One humanoid diver has embedded arms with force sensing and provides the sense of touch to the pilot through Force DimensionTM haptic interfaces—a 6D joystick with force feedback, similar to the technology used for robotic surgery. The human shape of Stanford’s robot also makes piloting more intuitive.
The LIRMM will continue developing more accurate positioning and control algorithms, primarily based on artificial vision. Simultaneously, they will also focus on the delicate handling of artefacts and on excavation sites at deeper and deeper depths.
“Currently, we work frequently and easily at 500 m, with about 20 shipwrecks investigated at such depths. We occasionally work at 1,000 m—last year we did one of the largest (145-metre long) deep 3D modeling on the 100-year-old Danton shipwreck. And now we want to reach 2,000 m in the near future. It wasn’t long ago that we would have never dreamt of reaching shipwrecks at these depths. But now, thanks to work in robotic engineering over the last decade, we have combined tech from healthcare, offshore, military, and the sciences to finally gain access to thousands of previously inaccessible sites. The future of underwater archaeology is truly exciting.”
Deep shipwrecks are time capsules of human history preserved for centuries at the bottom of the ocean. Now, thanks to the Corsaire Concept Project, we are almost able to discover their story and share it with the world.
Dr. Vincent Creuze, the Scientific Coordinator of the Corsaire Concept project (LIRMM).