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48 UAV, developed by Micro Multi Copters Aero Technology in China, has an endurance of up to four hours, giving it a range of 100 km for agriculture applications. The craft is powered by a fuel cell that converts hydrogen into electricity, with water as the by-product. For more than 20 years, Yamaha has been using the RMAX remotely piloted helicopter in Japan and South Korea, where it is used primarily for seeding and spraying. The company has also been working with the University of California, Davis to research the effectiveness of RMAX to spray vineyards, and last year it was granted the first exemption for precision agriculture in the US to test out the technology. As a result, Yamaha has developed a new version called the Fazer R specifically for precision agriculture. The craft uses a 390 cc petrol engine and carries a tank of 32 litres of spray instead of 24 litres in the RMAX, allowing the new version to cover up to four hectares (10 acres) before returning to refuel. The company has also increased the number of frequencies available for its Yamaha Attitude Control System II, which helps to avoid crosstalk. It uses a relatively simple laser rangefinder for December/January 2017 | Unmanned Systems Technology One key technology for precision land management – the term given to modern agriculture – is accurate positioning. While satellite navigation systems are improving in accuracy, other technologies are used to provide the positioning needed for autonomous tractors and UAVs. In November 2016, u-blox started shipping the smallest high-precision GNSS RTK (real-time kinematic) module available on the market based on GPS and GLONASS satellite-based navigation systems, with agriculture in mind. The NEOM8P GNSS receiver module measures 12.2 x 16 x 2.4 mm and provides centimetre accuracy through corrections sent from the u-blox base receiver. This data is sent over the RTCM protocol, with the RTK algorithms pre-integrated into the module to reduce its size and weight. The integration also helps reduce power consumption by a factor of five compared to board-level systems. This approach requires a local base receiver, however, which may be a challenge for large farms spread over hundreds of kilometres. Other positioning technologies use the error data from regional satellite-based augmentation systems, such as WAAS in the US, EGNOS in Europe, MSAS in Japan and the forthcoming GAGAN system in India. This extra data can be used to improve positional accuracy to within 1 m without needing a separate network. Another approach, Precise Point Positioning (PPP), reduces errors in the data by combining satellite orbit and clock correction data with error modelling in the receiver, which allows a single receiver to be used to provide the same performance anywhere in the world. Correction data is delivered via satellite to the same receiver used for GNSS signal tracking, and does not rely on other satellites or ground networks. Novatel works with sister company TerraCom to provide the receiver and satellite error data for the more accurate positioning from PPP needed for modern agriculture. RTK has also been extended to eliminate the need for a separate network, with RTK eXtended (RTX) technology providing position accuracy of under 4 cm. For example, the CenterPoint RTX from Trimble converges to full accuracy in between one and five minutes in particular regions, and less than 30 minutes worldwide, using the US GPS or Russian GLONASS satellites. One of its advantages is that it can continue working even if the correction signal is interrupted for up to 200 s, and there are different requirements for agriculture with a ‘fast restart’ version. This reduces the standard initialisation time to less than five minutes at the beginning of each day by starting up the tractor in the same place it was shut off the night before. Positioning technologies Adding a real-time kinematic module to a navigation system can dramatically improve positional accuracy (Courtesy of u-blox) Autonomous systems can help boost the productivity and efficiency of farmers, but there is no one system that meets every agricultural need