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Session A4: Integrated Inertial Navigation Systems

GNSS/INS Integration of Next-generation MEMS IMU Technology for UAV Applications
Marnix Volckaert, Bora Barin, Kristof Smolders, Danilo Sabbatini and Frank Boon, Septentrio, Belgium
Location: Pavilion Ballroom East
Date/Time: Wednesday, Apr. 22, 5:36 p.m.

In recent years, small Unmanned Aerial Systems (UAS) have become the platform of choice for many industrial and scientific applications where high accuracy is a mission critical requirement, such as photogrammetry, LiDAR scanning, mobile mapping, inspection tasks, etc. This has been enabled in part by the availability of miniature positioning and orientation sensors which can meet the strict SWaP requirements of the UAS platform. Accuracy of the position is required to correctly geo-reference imagery or other payload data, while accuracy of the orientation is critical for interpreting the recorded data and/or for controlling the trajectory of the UAS. The key in providing such positioning and orientation solutions is the integration of a light-weight high performance IMU with a high accuracy GNSS receiver, as in the Septentrio AsteRx-i product line. Recent advances in MEMS technology developed by Analog Devices now enable a new generation of integrated INS receivers by sourcing directly from the sensor manufacturer. This foregoes the integration of the MEMS IMU sensor in an IMU product by third parties, bringing down the cost to the end user while also improving the performance.
Septentrio has cooperated closely with Analog Devices to introduce an iteration in the AsteRx-i product line based on the next generation Analog Devices IMU, Falcon. Falcon is a miniature MEMS IMU which is factory calibrated for sensitivity, bias, alignment and point of percussion reaching industrial-grade accuracy levels. It uses dynamic compensation formulas, reducing the need for extensive error models in GNSS/INS integration. Having direct access to IMU data at sensor level provides more control of the signal processing chain; it also allows a better modelling of low-level error sources and avoids potential additional errors introduced by third party IMU manufacturers. Another benefit of this cooperation is quicker innovation by being independent of the product development cycle of an IMU product manufacturer.
The new INS receiver, AsteRx-i D UAS, combines the AsteRx-m2a GNSS receiver with a UAS companion board with the Falcon IMU mounted. To ease the integration with popular autopilot systems such as Pixhawk and ArduPilot, the receiver has an industry standard 44-pin I/O connector. The receiver also contains event marker inputs to accurately timestamp camera shutter or other payload events and to provide a position and orientation solution at the exact time of the event. The fully customizable PPS out signal can be used to drive or synchronize the payload. For easy data logging the receiver is equipped with an onboard Micro SD card.
The performance of the newly developed INS receiver AsteRx-i D UAS will be demonstrated by tests on a UAV, equipped with a high-end fiber optic gyro (FOG) INS as trajectory refence. A comparison will be made with our current AsteRx-i S UAS receiver, as well as with competitor products of similar grade, mounted in the UAV payload box. The results will demonstrate the feasibility of achieving industrial grade accuracy by sourcing the IMU directly from the sensor manufacturer.
The presentation will present the newest addition to Septentrio’s AsteRx-i product line, the AsteRx-i D UAS, developed in close cooperation with Analog Devices and specialized for the UAS industry. The innovation lies in bringing together the expertise in GNSS and MEMS technology. This enables a faster time to market upon each iteration of MEMS IMU technology, as well as cost savings for the end user along with higher performance from the optimally combined sensors.



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