Zubax GNSS positioning module - GPS/GLONASS + Compass + Barometer + CAN

Hi everyone,


Today we present our first product - Zubax GNSS. It is a high-performance open source positioning module for outdoor environments with doubly redundant UAVCAN bus interface. It's the right choice for any UAV or robotic application where safety, positioning accuracy and cost efficiency are paramount.

Being UAVCAN-interfaced, Zubax GNSS can be used out of the box with any UAVCAN-enabled controller, such as Pixhawk. Detailed instructions about how to configure Pixhawk for use with Zubax GNSS can be found at our documentation portal (see the links below). At the moment, the native PX4 stack already has complete UAVCAN support implemented in the stable branch. The APM stack doesn't have support for UAVCAN at the moment, but there were some successful experiments with it earlier so it will be there soon as well. By the way, any cooperation from the APM developer community is highly welcome!

Features

Sensors

  • High performance concurrent GPS/GLONASS receiver u-blox MAX-M8
    • Full RF shielding of the GNSS circuits ensures reliable operation in high-EMI environments
    • 35 mm high gain patch antenna with large ground plane for reliable reception even in urban canyons
    • Analog front end with LNA and SAW ensures high noise resilience
    • Rechargeable backup battery enables low time-to-first-fix (a few seconds)
    • Up to 15 Hz update rate
  • High precision digital barometer Measurement Specialties MS5611
    • Altitude resolution 10 cm
  • 3-axis digital compass Honeywell HMC5883L

Interfaces

  • Doubly redundant UAVCAN with standard connectors
    • Sensor measurements at configurable rates
    • Continuous self diagnostic and failure detection outputs
    • Configuration
    • CAN bus bitrate up to 1 Mbps
    • Can be used in non-redundant mode as well (one interface will be inactive)
  • Auxiliary serial port
    • Direct access to the u-blox module
    • Firmware update
    • Diagnostics and configuration via command-line interface

General

  • Extensive, continuous self diagnostics and failure detection make Zubax GNSS a favorable choice for safety-critical applications
  • Multiple redundant units can be used concurrently on the same UAVCAN bus
  • Sources are open and freely available for everyone:
    • Firmware sources
    • Schematics
    • 3D printable models of protective case and mounts
  • Low cost

Performance

The image below shows the performance of Zubax GNSS in comparison with another popular GPS receiver (u-blox LEA-6H with 25 mm patch antenna). Notice the deviation map, position accuracy estimates and SNR. This was captured in a shallow urban canyon of a large city. Zubax GNSS is on the left (click to enlarge):

This video features a highly precise, fully automatic landing of a Pixhawk-powered quadrotor with Zubax GNSS:

Links


P.S. Stay tuned for more UAVCAN-interfaced avionics. UAVCAN-enabled ESC and a UAVCAN-enabled something-quite-important are on their way to the market. Developers, please consider moving towards UAVCAN-centered ecosystem by supporting this protocol in your projects - learn more at uavcan.org.

Views: 9644

Comment by mP1 on September 27, 2014 at 1:01am

What is the horizontal accuracy.

Comment by Zubax Robotics on September 27, 2014 at 2:41am

Horizontal accuracy heavily depends on conditions. Under clear sky the maximum deviation should not exceed 1 meter, in a city (this is where the comparison mentioned in the topic was performed) it would be generally below 5 meters.

Comment by mP1 on September 27, 2014 at 2:56am

The asking price of $184 USD is basically double 3DR's sell price and the accuracy is worse and certainly not better, 5m is very poor.

Comment by Zubax Robotics on September 27, 2014 at 3:27am

basically double 3DR's sell price and the accuracy is worse

No.

Zubax GNSS significantly outperforms 3DR GPS due to the fact that, unlike 3DR's receiver, it is based on a high-end concurrent u-blox module (MAX M8) and has a much higher gain patch antenna. 'Concurrent' in this context means that it is capable of using multiple navigation systems simultaneously, in this case it is GPS and GLONASS.

You said that 5 meters deviation in an urban environment is 'poor' performance - sorry, you're wrong. If you take a look at the screenshot from u-center linked from the article you may notice significant difference in performance between Zubax GNSS and a competitor (and yes, the competitor is 3DR GPS, so called another popular GPS receiver (u-blox LEA-6H with 25 mm patch antenna)):

  • Peak deviation (~5 vs. ~25 meters)
  • Number of SVs available (18 vs. 9)
  • SNR
  • 3D accuracy estimate (1.45 vs. 6.9 meters)

Other than significantly outperforming vast majority of GNSS receivers currently available on the UAV market, our module also has full RF shielding on the GNSS circuits that allows to use it near high-EMI equipment such as video transmitters or high-performance on-board computers.

Comment by naish on September 27, 2014 at 4:29am

I'm glad to see that finally someone is moving towards CAN bus oriented devices. Anyway great product I will get one for testing. 

Comment by Johann van de Venter on September 27, 2014 at 5:33am

Referring to the screenshot of the software in the post, what software is that?

Comment by Zubax Robotics on September 27, 2014 at 5:55am
Comment by Paul Tweten on September 27, 2014 at 10:28am

Is the barometer better than pixhawks? How does it stack up to this? What justifies the extra $100? 

http://www.csgshop.com/product.php?id_product=173

Comment by Zubax Robotics on September 27, 2014 at 11:03am

It's exactly the same barometer as on Pixhawk.

As for the price - make no mistake, Zubax GNSS itself costs $149, but complete kit for use with Pixhawk costs $184.

The product you linked lacks the following:

  • RF shielding (lack of which implies problems near high-EMI on-board electronics, which is fairly common on FPV UAVs)
  • Analog front end (LNA, SAW)
  • Doubly redundant CAN bus interface
  • Barometer
  • Since you're comparing the price of that product with the price of the Pixhawk-compatible kit, I should also add that it lacks the necessary wiring
Comment by Peter on September 27, 2014 at 11:54am

Interesting. Any way to collect raw gps data and export it out as RINEX for post processing against a stationary base station?

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