Steel E-Motive robotaxi | Digest Maintenance strategy Ricardo used in-house modelling software to simulate timelines of 24hour duty cycles for the SEM1, including artificial traffic and rush hours, and found that a single charge should be sufficient for operating from 6am to 6pm. “People might find that hard to believe, but when you look at the duty cycle for taxis, you find there are a lot of lulls in demand throughout the day,” McGregor says. “For instance, there’s a big drop-off in passengers from mid-morning to midday. “That means it’s also easy to find a 20-minute window for an SEM1 to return to the depot and be cleaned of waste and wear that passengers will inevitably leave behind. It also provides an easy opportunity to fast-charge some energy back into the pack to operate for longer. So, with that kind of opportunity-based maintenance, range anxiety isn’t an issue for us.” Coates adds that conservative projections for gravimetric energy density through to 2030 have been overlaid onto the duty cycle simulations, and further support the project’s claims that the SEM1 (and by extension the SEM2) are configured optimally in terms of weight and energy for transport duties on modern roads. Future of the project Sustainability over the lifetime of the SEMs is a major focus for the project’s partners. Much of the programme has for instance explored how to minimise scrap, with re-use of scrap metal in the fabrication processes potentially enabling 90% use of the steels; conventional automotive production often yields rates as low as 50%. On top of that, the project identifies various ways to reduce greenhouse gases across the life cycle of the SEMs by 86% (by 2035, compared with theoretical 2020 figures). These include decarbonising steel production by using hydrogen and electric arc furnaces in place of coal, coke and gas, and developing autonomous vehicle control systems to smooth real-world drive cycles and optimise energy use. Although the cost of transitioning to a green economy are significant, WorldAutoSteel and Ricardo plan to continue their r&d into how interested parties might make viable commercial operations out of the SEM vehicles. “For instance, we have a project with Michigan Tech University, where researchers are evaluating how the SEM2 could be adapted for transporting goods instead of people,” Coates notes. “Buying vehicles in bulk is expensive, but if fleet owners can use SEM2s for logistics or last-mile deliveries during the off-peak hours for transporting people, that would greatly increase the hours per week the vehicles can generate revenue and the speed at which they break even on their investment. “As for the OEMs, those who understand how many variations and specialisations of steel there are consider it to be as tailorable as carbon composite,” Coates says. “Our portfolio currently has 64 grades of AHSS; by contrast, the last time WorldAutoSteel did a big project like this, only 27 existed, and that programme concluded in 2010. “That goes to show just how much product development there’s been over the past 13 years, and how much more we could do for different requirements in future mobility.” 63 Uncrewed Systems Technology | August/September 2023 SEM1 Robotaxi Battery-electric Single-speed front electric drive Four passengers Dimensions: 4095 x 1880 x 1850 mm Energy: 75 kWh Top speed: 130 kph Specifications Instead of having a cover, the battery pack’s carrier frame bolts under the SEM1’s floor, saving weight and making it easy to inspect and replace any damaged modules
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