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97 GNSS constellations and signals, while also providing robust signal reception at low-elevation angles,” said Julien Hautcoeur. “To that end, in early 2019 we evaluated many GNSS antenna technologies. The Alford loop antenna, which was first conceived in the 1940s, was selected as a starting point for the development because of its high gain at low elevation angles. During 2019 and 2020, we worked to improve the VeroStar antenna’s bandwidth, gain and axial ratio, while maintaining the Alford loop’s excellent low-elevation angle tracking.” Having high gain at low elevation angles is key, since L-band correction signals and GNSS signals are often received at low elevation angles. The VeroStar antenna also benefits in terms of reliability and functionality by being able to track L-band corrections, in addition to GPS/QZSS L1/ L2/L5, GLONASS G1/G2/G3, Galileo E1/ E5a/E5b/E6, BeiDou B1/B2/B2a/B3, QZSS L6, and NavIC L5 signals. Tallysman has also developed custom filters to mitigate signals at the edge of the GNSS bands, reducing interference from cellular signals, Iridium, Inmarsat and other sources. Hautcoeur added, “The 500 g VeroStar Pole-Mount antenna is ideal for land survey rover and autonomous maritime applications, the 340 g VeroStar Surface- Mount is designed to meet the needs of larger autonomous vehicles, and the 80 g embedded VeroStar and VeroStar Mini models are designed for smaller custom installations.” Fixposition has launched its new Vision-RTK product, which the company has developed as a highly reliable, high- precision positioning and navigation solution that fuses RTK-GNSS with inertial and visual sensing in a single unit. “Fixposition was formed from two separate Pioneer Fellowship teams at ETH Zurich, centred respectively on centimetre- accurate GNSS/GPS positioning and computer vision-based UAV navigation,” explained Zhenzhong Su. “GNSS accuracy degrades to tens of metres in urban canyons, and camera- based visual navigation simply does not work on dark or foggy days. This limitation is among the biggest operational bottlenecks for unmanned vehicles, but by combining the two aforementioned technologies we can overcome that.” The Vision-RTK weighs 57 g and consumes 4 W. It contains an IMU, a high frame-rate CMOS camera with a global shutter and two 20 Hz RTK- GNSS receivers compatible with GPS, GLONASS, Galileo and BeiDou. The software fusion engine, which forms the core of the company’s IP, has a latency of 10 ms, producing horizontal position accurate to 1 cm and velocity accurate to 0.03 m/s, including attitude output. Lukas Meier added, “Components were selected to produce Vision-RTK as a small module that could fit into any small UAV or autonomous ground vehicle. Ease of integration also prompted us to pick a multi- constellation GNSS and a MEMS IMU, while the camera with its global shutter and high frame rate was key for machine vision. “Our hardware is modular, so we can adjust quickly to different use-cases, and we’ve designed the software to be modular too, to smoothly integrate new functionalities into our algorithm.” Honeywell spoke with us about its new HGuide n380 INS, following requests from its n580 customers wanting an inertial navigation solution with similar performance capabilities but in a smaller form factor. “The n380 has a horizontal positional accuracy of 1 cm in RTK mode, heading accuracy within 0.1 º in dual-antenna mode, and level accuracy to within 0.33 º ,” said Chris Lund. The system weighs 320 g (compared with the n580’s 495 g) and takes up 260 cm 3 of space in a 9 x 6 x 4.8 cm housing, while consuming 3.5 W during normal operation. It receives GNSS signals from a range of constellations including GPS L5, GLONASS L3, and QZSS L5, and can use PPK and SBAS corrections in addition to the RTK processing and dual-antenna inputs. It also carries 16 Gbytes of internal storage for logging navigation data, as well as Honeywell’s navigation algorithms for use in land, sea and air vehicle applications, along with compatibility for Lidar systems for point cloud generation in mapping and inspection missions. Unmanned Systems Technology | December/January 2021 Fixposition’s Vision-RTK positioning and navigation unit The new HGuide n380 INS from Honeywell