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10 Platform one VectorNav has developed a new series of inertial navigation solutions for autopilots, gimbals and other unmanned systems and technologies (writes Rory Jackson). All three Tactical Embedded systems have been engineered into a footprint measuring 31 x 31 x 11 mm, giving them the highest performance-to-size ratio in the company’s portfolio. “Essentially we’ve taken the core technologies in our Tactical series and created board-mount versions, paring down the internal electronics and components into the smallest footprint possible,” said Jakub Maslikowski of VectorNav. “Even within that limited space, the IMU installed in all three products still offers tactical-grade performance – less than 1 º /hour gyro in-run bias stability and below 10 µg accelerometer in-run bias – at up to 800 Hz, all before our extended Kalman filtering is applied.” The lightest of the three products is the VN-110E, which weighs 12 g and consumes up to 1 W at peak power. “The VN-110E is an IMU but also includes an onboard AHRS [Attitude Heading & Reference System] algorithm,” Maslikowski explained. “The AHRS takes the acceleration, rotation and magnetic data from the IMU to output heading, pitch and roll estimates at up to 400 Hz.” The second product is the 14 g VN-210E, which also contains an IMU/AHRS but includes a multi-band GNSS receiver and INS algorithm, to couple the GNSS and inertial data to output position, velocity and attitude for dynamic applications. Lastly, the VN-310E weighs 15 g, consumes up to 1.6 W and comes with the same technologies as the VN-210E while also integrating GNSS- compass functionality (via two GNSS inputs for antennas), to enable heading to be calculated without the need for movement or a magnetometer on the unmanned vehicle. “The proprietary differential GNSS- Compass enables heading angle calculations without the need for vehicle dynamics, which is critical for multi-rotor UAVs, UGVs or any vehicle measuring and tracking objects at varying distances while it and its payload are stationary,” Maslikowski said. VectorNav’s extended Kalman filtering on the VN-210E and VN-310E provides pitch and roll accuracy to 0.015 º , and heading accuracy of between 0.05 º and 0.1 º , while the VN-310’s heading accuracy can be maintained at 0.08 º RMS in static conditions. Given that these new products might often be installed in avionics bays or gimbal housings, where heat, conductivity, RF emissions and vibration can be highly concentrated, they have been optimised for thermal performance, EMI and manufacturability. “We’ve also changed the boards’ interfacing and general architecture,” Maslikowski said. “On our bigger Tactical series, we’d install RS-422 as a default with RS-232 as an option, both using Mil-Std connectors, and then SMA coax for the GNSS antennas. “There are also a lot of power regulation and other components on board to bring them into line with Mil- Std and DO-160G certifications for EMI, power and so on. “Because the Tactical Embedded series has been designed to offer easier and deeper integration into an electronics assembly, we were less constricted by having to meet those standardisation requirements. “Instead we’ve been able to focus on packaging the IMU, GNSS receivers and surrounding parts into as small a package as possible while also integrating enough processing power to run our AHRS algorithms, the INS, the GNSS-compassing, calibration and some other features available now or to follow.” Maslikowski also noted that the software features running on the Tactical Embedded series are the same as those in the company’s Industrial and Tactical products. If an end-user wanted to switch to (or adopt) the new series for an autopilot or payload gimbal, they could therefore do so without needing any significant software rewrites or major firmware updates. Board-mount units unveiled Navigation October/ November 2020 | Unmanned Systems Technology The Tactical Embedded systems are designed to have the smallest possible footprint