Unmanned Systems Technology 002 | Scion SA-400 | Commercial UAV Show report | Vision sensors | Danielson Trident I Security and safety systems | MIRA MACE | Additive manufacturing | Marine UUVs

6 Autopilot specialist UAVOS used the Commercial UAV show at Olympia (see page 34) to showcase its new-concept atmospheric satellite, an autonomous UAV that hovers at high altitude, normally to act as a base station for internet connection. A long wingspan is a fundamental requirement for this application, and rather than have a single central fuselage carrying the propulsion system and the payload, the UAVOS craft consists of four or more fuselages linked by a single wing. Each fuselage takes an equal share of the payload, and each has its own propulsion system. The wing has a high degree of flexibility, and the individual fuselages each have an autopilot that is central to controlling its dedicated propeller motor, its horizontal tail elevator and winglets with optional air brakes on the adjacent wing sections. The various controllers have (wired) data links, and the control software operates the entire craft as a single unit. If one of the fuselages starts to move out of a desired position relative to the others then the control system will react to stabilise the craft through the common wing, which can twist and bend. The individual operation of each fuselage and the inherent stability of the combined unit help protect against turbulence – indeed, the control system manipulates the entire craft to obtain the most efficient flight. The wing carries solar panels, and these top up the batteries that power the propeller motor in each fuselage. The batteries also power the autopilot-based control system as well as the payload. At night, in the absence of solar energy, the craft is allowed to glide. Over ten hours it will drop from around 30,000 m to around 15,000-20,000 m – still above civil aviation airspace – and then the next day it will be powered back up to its original altitude. The craft has been designed to allow a total flight duration of about five years, which is the planned routine maintenance interval given its (advanced composite) construction. Having landed for refurbishment, it needs additional power for its initial climb to 30 km, and this is provided by a battery system that is dropped back by parachute once it has done its job. There is a temperature issue for batteries at high altitude, so this approach allows the ongoing use of a very small, lightweight lithium-polymer buffer battery that can be protected in a thermal box in its specific fuselage. The prototype on show at Olympia had six fuselages and a 50 m wingspan. Head of r&d at UAVOS, Aliaksei Stratsilatau, remarked, “The proposed aerodynamic arrangement has a linear weight increase relative to the span, unlike a classical arrangement. This allows us to create an aircraft significantly different in its performance from the previously designed airframes.” Stratsilatau added that the design makes use of the company’s distributed control system, which he said the company has been working on for more than ten years across a number of unmanned systems. “Our concept is different because it has dual CAN potential and distributed processing,” Stratsilatau said. “The system consists of several nodes with different functionality and all connected in a CAN network. We connect as many nodes as necessary to achieve redundancy and distribute the computing. This means that if you lose a node nothing changes and the system remains stable.” The base modules measure just 25 x 36 mm and are stackable to form a more complicated node if required. Mission-critical info for UST professionals UAVOS flexes its wings A four-fuselage configuration of UAVOS’ atmospheric satellite Atmospheric satellite Spring 2015 | Unmanned Systems Technology Platform one