Unmanned Systems Technology 016 | Hydromea Vertex AUV | Power management systems | Unmanned Space Vehicles | Continental CD-155 turbodiesel | Swift 020 UAV | ECUs | DSEI 2017 Show report

10 Platform one October/November 2017 | Unmanned Systems Technology A team from China’s Wuhan University of Technology is working on a cooperative maritime search-and-rescue concept that uses a combination of UAVs and supporting USVs (writes Peter Donaldson). The system is designed to overcome the range and endurance limitations of current electrically powered UAV technology by recharging a UAV’s batteries wirelessly. The invention comprises a system that includes a UAV and a USV-mounted wireless charging system with a docking platform for the UAV. The wireless charger includes a battery pack and power supply unit for Researchers at the University of Zurich (UZH) and NCCR Robotics have used a new type of camera to enable UAVs to fly autonomously and navigate in low light (writes Nick Flaherty). The so-called event cameras, which were invented at UZH, do not need to capture all the light landing on the pixel array; instead they only measure the change in brightness for each pixel. With the right processing electronics, this provides sharp vision even during fast motion or low-light environments, as they transmit the intensity changes at the time they occur, in the form of a set of asynchronous events. This provides a very high dynamic range of 140 dB compared with the 60 dB of a standard camera. As all the pixels capture light independently, such sensors do not suffer from motion blur. The UZH researchers combined the event camera output with a standard the transmission coil, which creates a current in the UAV’s receiving coil through magnetic induction to charge its battery. The charging circuit aboard the UAV includes a rectifier and a voltage regulator between the receiving coil and the battery. A hold-down system analogous to the kind of decklock system used by small warships that operate helicopters is based on an electromagnet switched on by a variable resistor that detects the UAV when it lands. When charging, the distance between the receiving coil on the UAV and the charging pad on the boat is about 4 cm. The team also considered electric field coupled charging, but rejected it on the image sensor and new software to allow a prototype UAV to travel in circles in a room at 1.68 m/s (5 kph) in low light, and with the lights in the room being switched on and off. The UAV is based on a DJI frame with a Pixhawk PX4FMU autopilot and Odroid XU4 computer, which contains a 2.0 GHz quad-core processor running Ubuntu Linux 14.04 and the Robotics Operating System (ROS). A Davis 240C sensor, equipped with a 70 º field-of-view lens, is mounted on the front of the quadrotor grounds that the technology is not yet sufficiently mature. With four hosted UAVs, each USV can constantly keep two in the air, on patrol, while the other two recharge on deck. The software-controlled operation is based on a combination of standardised search patterns in which the USV follows a track line pattern of equally spaced legs at 90 º to the line of advance, while the UAVs conduct repeating semicircular or contracting spiral patterns in sub- regions of the search area. The lengths of cruise segments undertaken by the USV is based on calculations of the UAVs’ endurance, optimising area coverage rates. • Power management focus, page 32 and connected to the Odroid computer via USB 2.0. “There is still a lot of work to be done before these vehicles can be deployed in the real world, since the event camera used for our research is an early prototype,” said researcher Henri Rebecq. “We have yet to prove that our software also works reliably outdoors.” Land-sea team to the rescue Camera has low-light trick Platform collaboration Vision systems Zurich University’s event camera needs only the changes in pixel brightness to be able to produce sharp vision, without motion blur