97 “During our PhD research at ETH Zürich, we experimented by modifying an ANYbotics ANYmal UGV [see Issue 40], adding wheels to its four legs and, of course, that made it much faster, but the far more important benefit was that energy consumption went down significantly by being able to move on wheels instead of legged locomotion in many places,” says Swiss-Mile’s co-founder and CTO for software, Lorenz Wellhausen. “Instead of being limited to one hour on a single battery charge, our modified robot went for two hours. The wheels significantly extend the operational domain of any legged robot.” With such potential for greater uptime for indoor and outdoor operations, including on hazardous sites such as construction, Swiss-Mile was spun out from ETH Zurich and incorporated as a company in mid-2023 – now with 13 staff and five prototype UGVs. Swiss inspired, Chinese built The Swiss-Mile founders’ early research used the aforementioned ANYmal from its fellow ETH Zurich spinout, ANYbotics, but since its founding, the former has switched to using the B2-W quadruped UGV from Unitree Robotics, based in Zhejiang, China, as a platform for its UGV development and commercial services. “Unitree seems to have already seen what we were doing in a research context, and gotten inspired to build a wheeled version of its B2 UGV [B2-W meaning B2 with Wheels], so we were able to start buying those at a very good price and they came ready-made with motorised wheels,” Wellhausen says. “That means we don’t have to do any significant hardware modifications and we can focus on our software work, as well as on finding ways to suit the UGV to market applications.” With its 22 cm-diameter wheels, the B2-W has a top speed of 6 m/s (21 kph). It weighs 75 kg and can take payloads of 60 kg. Able to climb stairs or inclines of 45°, it runs on an Intel i7 CPU and is IP67-rated for ingress protection. Importantly, Swiss-Mile only uses the B2-W’s hardware and none of its software; every piece of code on Swiss-Mile’s UGVs is unique to the Swiss company. “We had worked heavily on creating our own algorithms at a time when wheeled-legged robots were a totally new robot morphology, and we’d made our IP while also coming to grips with hardware challenges, like getting the wheel hardware right for both driving and stepping over obstacles,” he recounts. “With bio-inspired robots, you can always take engineering inspiration from nature: how a dog walks, how a bird flaps its wings, how a fish swims, for example. But there is no wheeled-legged animals in nature, and we, as humans, don’t necessarily have the intuition for it. So it has been really hard from the beginning, when we tried to use model-based control approaches to design our motion, to ensure the robot only steps when it needs to, or only drives when efficient. Swiss-Mile UGV | UVIO On a single battery charge, our modified robot went for two hours. The wheels significantly extend the operational domain of any legged robot Uncrewed Systems Technology | August/September 2024 Milo walks to traverse stairs or uneven and cluttered terrain; elsewhere, it rolls to save energy and turn more efficiently (Image courtesy of Swiss-Mile)
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