How the new Ellipse INS/GNSS makes entry-level RTK reliable?

Ellipse inertial sensors have always benefitted from a reputation of robust and reliable sensors. The new generation reinforces this proposition and opens new markets with centimetric real-time navigation and post-processing. How does this 3rd generation of INS/GNSS make new entry-level RTK reliable?

1 – A Superior Inertial Measurement Unit

Industrial-grade Ceramic IMUs

For the Ellipse Series, SBG Systems only selects industrial-grade accelerometers, gyroscopes, and magnetometers to build inertial measurement units with a ceramic package. All IMUs are intensively tested to ensure they are able to cope with our demanding production process.

Calibrated from -40 to 85°C

Ellipse miniature sensors benefit from a high-end calibration using multi-axis rotary tables and temperature chambers. All inertial measurement untis are individually calibrated in temperature from -40 to 85°C and shipped with their calibration report showing all the parameters of the calibration. Calibration enables the highest performance in all the environmental conditions.

From Prototyping to Production, All Sensors Behave the Same Way

It is important when selecting a sensor to make sure that all the future sensors will provide the same performance as the one you have tested with your prototype. The specific in-house qualification process ensures the same level of performance over lifetime with no significant drift. When calibrated, Ellipse inertial sensors go through a strict screening process. If the sensor does not meet the specifications, it is removed from the production line.

All Ellipse sensors benefit from a 2-year warranty

2 – A Superior GNSS receiver

RTK in a 17-gram INS/GNSS: Convergence Time and Accuracy

Up to now, traditional entry-level GNSS receivers were only offering single-band design while survey-grade GNSS receivers offered multi-band frequency. The new generation of GNSS receivers delivers multi-frequency tracking which enables a better multi-path and anti-jamming spoofing resilience. More signals also allow better atmospheric error correction and enable very high-accuracy RTK positioning and dual-antenna heading computation using almost instantaneous RTK fix.

While using a single-band design, you would need minutes of convergence time in a fully open sky environment, using a multi-band design makes it possible to achieve this performance level within a very few seconds.

Instantaneous Heading in All Conditions

Depending on the application, you will have to cope with low dynamics or difficult magnetic conditions.  The Ellipse Series offers different types of heading: magnetometer, single-antenna or dual-antenna GNSS heading. From our experience, using a dual-antenna INS solution might help solve most of technical and environmental challenges.

Read the article on all heading methods.

Impact of Multi-constellation on RTK

Below is an automotive test result conducted in challenging GNSS areas such as urban canyons and tunnels. Qinertia post-processing software has been used to analyse the data. The first graph shows the Post-processed RTK maximum performance (76%) using the four constellations: GPS + GLONASS + GALILEO + BEIDOU. Below are the results when constellations are taken off the computation: the fix rate is down to 73% without Beidou, to 67% in GPS+GLONASS only, and only 49% for GPS only.

Having more constellations is always a good idea in challenging conditions, that’s why we offer all the constellations as standard for all SBG inertial navigation systems, with no extra cost.

3 – Post-processing with Qinertia

After the mission, the SBG in-house post-processing software named Qinertia gives access to offline RTK corrections from more than 7,000 base stations located in 164 countries – and always up-to-date. Advanced tight coupling algorithm has been designed by SBG Systems to deliver the highest accuracy and maximize RTK availability. When you are far from a base station, Qinertia automatically generates a Virtual Base Station (VBS). This VBS is created at the nearest place of your trajectory in order to achieve the best position accuracy.

This article is an extract from the webinar “How latest RTK + Inertial technology enables accessible & reliable centimetric navigation” organized by Inside Unmanned Systems.

Watch the full replay on youtube: https://www.youtube.com/watch?v=d2zA5IWe3Zw

SBG Systems is honoured that the Ellipse-D Inertial Navigation System named as Finalist for the AUVSI XCELLENCE Awards.