Inside GNSS Media & Research

JUL-AUG 2018

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A U G U S T / S E P T E M B E R 2 0 1 8 InsideGNSS 25 of Minnesota. Joining Gebre-Egziabher as panelist experts are Ryan Dixon, chief engineer of NovAtel's SPAN® GNSS+INS products group, David Gaber, marketing and business development at Epson, and Andrey Soloviev, Principal at QuNav. TRENDS AND IMPLEMENTATION Soloviev, whose research interests focus on all as- pects of GNSS signal processing and estimation as well as multi-sensor fusion for navigation applica- tions, presents on GNSS+INS integration with an emphasis on major trends along with examples of implementation and applications. He noted a big increase in recent years in the use of less costly inertial sensors based on MEMS tech- nology, covering a fairly large spectrum of inertial sensor specifications. "It covers almost all the way to the tactical grade of the spectrum to very low cost consumer grade iner- tial sensors that you can put in your cell phone to use for automotive applications," he said, "and the quality of MEMS sensors improved quite significantly over the last few years. That makes it possible to consider application of integrated GNSS inertial for a variety of GNSS degraded and GNSS environments such as urban canyons, parking garages and tunnels." The mitigation of inertial error drift can provide a main challenge, so Soloviev suggests the use of advanced integration techniques to provide a solu- tion. Loose coupling (integration at solution level) has limitations that include the fact that only sparse GNSS fixes can be obtained resulting in extended GNSS outages. That's why tight coupling and deep integration are highly recommended. With tight coupling (integration at the mea- surement level) the availability of (partial) GNSS updates increases, while the deep integration (in- tegration at the signal processing level) delivers weak signal recovery and multipath suppression. Soloviev shows how inertial navigation outputs are fairly limited when the GNSS has degraded environments, showcasing an example of trying to navigate in an urban canyon type of scenario. This case resulted in an extended number of GNSS outages. That's why integration with other sensors (and sources of navigation data) must be used, for ADDITIONAL SUPPORT •   Contact NovAtel for a copy of the SPAN Land Vehicle   Performance Analysis Paper •   Also, follow NovAtel on Social Media for the latest release   and updates:  Facebook:  Twitter: @novatelinc  Linkedin: THE PANELISTS David Gaber, marketing and business development at Epson Ryan Dixon, chief engineer of NovAtel's SPAN GNSS+INS products group Demoz Gebre-Egziabher, professor, Aerospace Engineering & Mechanics, University of Minnesota Andrey Soloviev, Principal at QuNav AT ATTENDEES ANTED TO KNO Participants had the chance to ask questions during the webinar. Here are a few of those questions: •   In terms of the noise levels when you do carrier phase  difference measurements and integrating it with INS, can  you comment on what the noise levels are if the difference  actually amplifies it?  •   Is there a standard definition as to what people call loose,  tight, deep, ultra-tight GNSS, INS integration? •   When it comes to interpreting numbers on inertial IMU spec  sheets, how does one interpret those conditions? Should they  interpret those as worst case performance numbers? Best  case? Or somewhere in between? •   Have you considered PPP (precise point positioning)  techniques with INS GNSS processing? Given the convergence  issues what would you expect the accuracy to be? •   Do you (Epson)  differentiate the application scenarios such  as UAV and ground and if so, do you regard Epson products as  MEMS or something else? •   Can you elaborate on the Coriolis effect and why it is or is not  used in some of the test cases discussed? •   What are the key challenges in tightly coupled GNSS INS  integration for centimeter level of accuracy? TO WATCH THE FULL WEBINAR, GO TO: https://attendee.

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