Unmanned Systems Technology Dec/Jan 2020 | Phoenix UAS | Sonar focus | Construction insight | InterGeo 2019 | Supacat ATMP | Adelan fuel cell | Oregon tour | DSEI 2019 | Copperstone Helix | Power management focus

83 The vehicle Copperstone has been working to produce two versions of its screw- propelled vehicle. One, unveiled last November, is the Helix 25 (named for its 25 kg payload- and battery-carrying capacity), which has an empty weight of 85 kg and measures 125 cm long, 125 cm wide and 62 cm tall. It has a rated top speed of 2 m/s (7.2 kph) on both water and hard ground, with a recommended survey speed of 1.8 kph, and the typical battery endurance gives 14 h of operation up to a 25 km range. The other vehicle, the Helix AR2, is larger, and although many of its specifications are still to be finalised before its public release, its maximum payload capacity could be 300 kg. It has a top speed of 1 m/s (3.6 kph) on water and 7.2 kph on hard ground. The Helix 25 is being built primarily for the water-monitoring portion of operations, while the AR2 (given its expected larger payload capacity) will be better suited for heavy-duty tasks such as geotechnical measurements and mud or tailing samplings. However, both vehicles can be used for largely the same tasks, and operate using essentially the same propulsion, data links, autonomy and other equipment. The systems are typically powered either by marine lead-acid batteries (being a long-proven technology preferred by some clients) or lithium- polymer packs for longer endurance. Most notably though, both vehicles feature a set of screw-type propulsion tracks, designed around hollow, sealed aluminium cylinders (or ‘scrolls’), which are the result of Copperstone’s need to float on water while also generating enough traction on ponds and soft terrain. The first models for testing and maturing this propulsion configuration were fielded in November 2015. Field work has been key to developing the technology and determining its limitations, as existing CFD software lacked significant data on the terra- mechanical interactions between mud and screw-propulsion tracks. “The first designs had a single, long scroll on each side, but in the latest designs we’ve switched to having two per side – so four scrolls and four motors in total,” says Olmedo. “We’ve also optimised the angle for both forward and reverse propulsion, and being able to turn well on mud.” Preparation and approach The Helix rovers are transported by trailer and road from Copperstone’s facility to the required tailings storage facility, although the Helix 25 is small enough to be transported by an aircraft or pick- up truck. Before starting operations, Copperstone will have received a GNSS location from its client (likely to be a mine operator or tailings facility operator) from which they want samples collected. From that, waypoints can be input into the Helix rover from a GCS tablet. “The rovers are instrumented to be able to move autonomously, either by a series of GNSS waypoints or just a straight-line trajectory,” Olmedo notes. “However, we have also chosen to teleoperate them in real time on a few early tests, particularly when they are moving over a new kind of soil for the first time, to get a tactile feel for how they’re handling the different terrains.” Most often, a particular pond will need multiple rounds of sampling and survey. Copperstone’s operations team will directly control the first outing, with subsequent rounds conducted autonomously once the team is sure there are no hazards in the terrain. The Helix is monitored at all times from a ruggedised laptop, with a live video downlink available within a 2 km Copperstone Helix amphibious vehicles | In operation Unmanned Systems Technology | December/January 2020 The Helix vehicles are used to safely sample and study waste products from bitumen extraction The Helix AR2 (pictured) and Helix 25 were developed with screw-propulsion tracks to travel on water, mud, and land