100 the end-user’s medium- to long-term expenses,” Wellhausen explains. Future work may include logistics, such as Milo moving heavy tools and materials for construction workers, but this would require engineering added subsystems for loading and unloading, such as robotic arms or gantries. Hence, Swiss-Mile is focusing on the first two use-cases to secure market share and revenue, such that its future growth will come from proven commercial successes. “Whichever use-case we’re doing, the core autonomy stack is the same, needing no software adaptations per the environment for the locomotion, obstacle avoidance and so on to work,” Wellhausen says. “There might be rules you need to follow on construction sites, pathways you use or don’t use, restricted areas, that sort of thing, but those are just minor, surface-level tweaks.” A Swiss-Mile engineer is always present at its proof-of-concept deployments to ensure the system is safe and to perform a pre-operational checklist. That involves looking for signs of damage on Milo’s hardware, listening for wear or jamming in its joints, and ensuring there are no obstructions or obscurants on the payloads before it sets off for the day. Do the locomotion Milo will roll around the construction site at 2 m/s (a safety imperative speed limit) until it identifies some stairs, at which point it will switch to walking mode. Otherwise, it will roll so long as the terrain is reasonably flat, including in slightly curved paths, as it can slightly angle its body posture to drive forwards with a turning radius rather than needing to stop in place and then step to rotate itself, as legged UGVs do at present. “It still steps if it must turn in place, and it sidesteps if needed, and if it slips or loses balance it steps to stabilise itself. Those are places where nature has designed the leg for good work,” Wellhausen notes. “We make sure to choose the right tyre for optimising traction across different terrains. In construction sites, we would pick a high-grip tyre, something akin to a mountain bike tread, to minimise slipping. The size of the wheel must also be chosen carefully, because a bigger wheel will drive better over rugged ground, but be worse at climbing stairs with secure footing.” Slip is detected from the joint motors’ and wheel motors’ data on speed and torque, and from the onboard IMU, with the neural network compensating accordingly with whichever steps, posture or mode switching it has determined is sensible. One thing it does not need to avoid is humans as trials currently only run after the sites have been cleared of personnel for safety reasons, but it has been trained to do so, given the work that Swiss-Mile anticipates carrying out commercially one day. Stand proud While walking UGVs can push doors open or use automatic sliding doors, if they encounter a pull door they must either return from whence they came or ask a nearby human for help. Milo, by contrast, can stand on its hind legs, reaching with its front legs, and gripping handles with its front wheels to pull doors open. Programming the robot to stand was originally done by Wellhausen and his colleagues at ETH Zurich on a whim, simply to see if it was possible. Only after they managed it did they come up with other ideas on how the standing function could be made useful. “First, we trained it to grip packages and move them around a little. Then we focused on door manipulation, and in construction sites it could be used to move non-heavy objects blocking emergency exits and similar sorts of tasks,” Wellhausen says. “There is still a bit of optimisation work to do with door-related intelligence. Milo needs to consistently recognise whether a door is left-hinge or right-hinge, or if it can only be pulled versus being push or pull, for instance. And we’re dead-set on the robot figuring that out autonomously without needing a human.” Building success Data collected from change-monitoring surveys will be analysed post-recovery of Milo, using the customer’s postprocessing systems (including COTS software designed for progress evaluations on construction projects), and no prospective end-user has yet required real-time video or photo streams from the UGV. August/September 2024 | Uncrewed Systems Technology The company will switch from smaller wheels to larger ones depending on the degree of grip needed (Image courtesy of Swiss-Mile)
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