Uncrewed Systems Technology 043 l Auve Tech Iseauto taxi l Charging focus l Advanced Navigation Hydrus l UGVs insight l MVVS 116 l Windracers ULTRA l CES 2022 show report l ECUs focus I Distant Imagery

12 A researcher at the EPFL, in Switzerland, has developed an exoskeleton that can carry spherical surveying robots into lunar caves (writes Nick Flaherty). The caves are 100 m below the surface of the Moon, and space agencies want to send robots to investigate them. “On the Moon’s surface, the temperature is +150 C during the day and -150 C at night,” said researcher Lucas Froissart at EPFL. “In these subterranean caves, which can be reached through natural, vertical pits, the temperature is -30 C, and there’s no radiation. Since the climate is constant and tolerable for human beings, these tunnels could conceivably serve as base camps.” Working with the Japanese space agency JAXA, which specialises in spherical robots, Froissart developed a mechanism capable of propelling six explorer robots through the lunar tunnels. “The exoskeleton is designed to be dropped into a lunar pit, which is about 100 m long,” he said. “When it touches the ground, three explorer robots are propelled at a 45 º angle in order to go as far as possible into the cave. The other three are released on the spot to collect immediate data.” His tests had to take into account not only the height of the fall but also the weightlessness and lack of air resistance on the Moon. Froissart calculated that he had to drop his exoskeleton from a height of 20 m on Earth in order to simulate lunar conditions. The exoskeleton is design to be used with the spherical robots developed for the Daedalus (Descent And Exploration in Deep Autonomy of Lava Underground Structures) project. Led by researchers at the Julius- Maximilians-Universitat of Wurzburg, in Germany, the project has developed several prototypes of a spherical robot device equipped with a 3D Lidar, stereo camera and a locomotion subsystem, as well as auxiliary housekeeping sensors. The Lidar aims to create a 3D model of the inside of the caves using a 2D Lidar sensor and IMU. A drive based on the impulses generated by the conservation of angular momentum moves the sphere around, and the scans were combined not only with orientation but also with position information. The test results showed better performance in terms of 3D mapping than that achieved by rotating the 2D laser scanner separately from the motion of the sphere. Froissart used scaffolding on a building on the EPFL campus to drop the exoskeleton, with six beach balls to represent the spherical robots. A few hundred tests later, the balls were propelled several metres the moment the structure hit the ground. Lunar caves robot system Space vehicles April/May 2022 | Unmanned Systems Technology Testing the exoskeleton involved dropping beach balls representing the spherical robots from a building at the EPFL