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

49 Construction | Insight safety regulations made that problematic, however, so with a partner we developed our own gearing and design for a winch system,” Arnott says. “We mounted that on a UAV, and fitted a pressure release vessel on the bottom of the winch that opened at the right depth to collect water samples across the pond. That allowed us to build a model of what was going on in the reservoir so that development could proceed.” Buildings maintenance Aspira is a technology company that licenses and leases UAVs to enable tall and inaccessible structures to be treated with specialist coatings, a task conventionally handled by construction and maintenance workers erecting scaffolding to spray structures on foot or by using cherry pickers – at great time and therefore cost. The coatings are effective at cleaning buildings and protecting them against build-up of bio-fouling and other dirt. “By using UAVs you reduce the risks of working at height, increase accessibility and reduce the expense of the task. We’ve done jobs in half a day that had previously taken maintenance teams many days to complete,” says managing director David Jolley. “The most recent of those was applying an algaecide to a building that was horribly green from algae staining. By the time we’d finished, the building was back to its original white colour.” The company spent two-and-a-half years developing its Aspiracopter UAV, an octocopter that has successfully carried out commercial operations. However, it has now developed a new version for the construction, maintenance and facilities management companies serving the building sector. The new version is designed with its motors guarded and in a coaxial X-8 configuration, rather than adopting its eight-armed predecessor’s airframe. The spray application is delivered from a ground pump through an umbilical hose, and is sprayed at pressure onto the wall or structure through a nozzle on the end of a lance protruding from the front of the UAV. A horizontal ‘push-pull’ motor is installed at the rear of the craft to prevent it having to tilt forwards or back when moving towards or away (respectively) from a wall, since doing so would alter the aim of the spray lance. “The motor is linked to our bespoke flight management system, so that when the UAV is in ‘proximity mode’ it can maintain a set distance from the building and a level flight attitude,” Jolley notes. “We have CAA authorisation to fly up to 30 m, so we can work commercially on buildings that are about nine storeys high, but the new Aspiracopter will have more power, which we anticipate will enable us to work at up to 60-100 m.” Although the UAV is flown manually, Aspira integrates significant sense-and- avoid autonomy to prevent accidental collisions with the building while it’s flying, as GNSS is unreliable for working amid buildings, particularly in urban canyons. A series of sensors provide the UAV’s real-time wall distance detection, but when spraying close to the building, the mist that generates has been found to interfere with laser measurements. “The system has had to be enhanced to ensure accurate measurements can be maintained through any spray mist that’s generated,” Jolley says. “Our intelligent flight control system uses a number of algorithms, using data inputs from the sensors to autonomously maintain the set distance from the wall. “We started with a third-party supplier for the software build, but now we develop and refine our autonomy and other code in-house,” he adds. “There’s a camera mounted too but it’s currently for the operator’s visual feed, although we anticipate integrating it into the flight control system in the future.” Conclusion With so many autonomous systems nearing full readiness and certification for implementation, it might not be long before entire developments can be built autonomously. By enabling sharp improvements in worker safety and falling costs of construction, these unmanned vehicles stand to enhance the quality of life for citizens all over the world. Unmanned Systems Technology | December/January 2020 Aspira’s UAV integrates a motor on the back to control its distance from walls while spraying solutions on them (Courtesy of Aspira)