Unmanned Systems Technology 014 | Quantum Tron | Radio links and telemetry | Unmanned Aerial Vehicles | Protonex fuel cell | Ancillary systems | AUVSI 2017 Show report

10 Platform one June/July 2017 | Unmanned Systems Technology Using very accurate inertial sensors supported by other high-specification sensors such as multi-beam echo sounders has enabled AUVs to achieve metre-level accuracy with terrain-aided navigation (TAN) in sea trials (writes Peter Donaldson). However, the sensors are expensive and limit the technique to larger AUVs, while current TAN software won’t produce accurate results with lower-grade sensors. Now a Chinese research team from Southeast University in Nanjing and Yungcheng University in Yungcheng has developed new TAN software to solve this problem. Described as a tightly coupled navigation scheme, the software estimates critical sensor errors by incorporating raw sensor data into an augmented TAN system that includes an inertial sensor. This sensor serves as a reference from which other sensor errors can be 3W has set down a milestone in UAV engine development by launching the first commercially available (Wankel-type) rotary to exploit direct injection (writes Ian Bamsey). The 180 cc four-stroke unit, which weighs less than 10 kg complete with starter/generator on the end of its crankshaft, produces 38.5 bhp at 7500 rpm, with the electrical machine adding 20 bhp (15 kW) in ‘hybrid mode’, for example to assist take-off. The ground- breaking direct injection system operates from 40 to 120 bar and can be used for gasoline or heavy fuel. Designed and developed in-house, it is controlled by a new ECU devised in conjunction with an undisclosed partner. Dyno testing took place in 2016, with the first flight on an undisclosed vehicle in February this year. 3W said it has already sold ten of the engines. Given that these days apex seal technology is well developed, the Achilles heel of any rotary is cooling the rotor bearing since it nestles deep within the core of the engine, uncomfortably close to the rotor’s combustion faces. 3W has yet to reveal precisely how it has overcome this challenge, other than to report that there is innovative oil cooling for the rotor and its bearing. The engine can be made available in one- through to four-rotor (hence 720 cc) versions, and it can be tailored for helicopter/VTOL applications. Fuel consumption is quoted as 340 g/kW. estimated. It also calculates 3D distance errors, providing measurement updates through a particle filter algorithm to calculate both the absolute and bounded error in the position estimate for the AUV. The team said the system produced good results, with the most accurate navigation in areas where the sea bed was rough enough to be able to distinguish one location from another. Accurate TAN costs to sink Rotary uses direct injection Underwater vehicles Airborne vehicles A new algorithm will allow low-cost sensors to provide terrain-aided navigation under water 3W uses an innovative but undisclosed method of cooling the engine’s rotor