At mRobotics our commitment continues with the DIY community. From San Diego California we design and manufacture the necessary hardware to build platforms and solutions based on Ardupilot and PX4. And now we show you the next high-tech GPS that has build-in CAN, which includes many and special improvements to achieve maximum accuracy in positioning and guidance for safe navigation.

One of them is that we have incorporated the RM3100, a new Geomagnetic Sensor. Like a pair of glasses, the RM3100 Geomagnetic Sensor enables you to see magnetic fields clearly. 

The RM3100 Geomagnetic Sensor is the highest performance sensor in its class with over 10 times better resolution and over 20 times lower noise than the leading Hall Effect sensor. It makes precise magnetic field measurements, which enables accurate calculation of heading and orientation. The earth’s magnetic field provides absolute reference for heading measurements and accurate motion tracking. Geomagnetic sensors are used to measure the earth’s magnetic field; however, in real world conditions, the earth’s magnetic field is often distorted by other surrounding fields. System components such as batteries, shielding materials, or motors will distort the geomagnetic field near the sensors. An additional design challenge is the changing magnetic environment that temporarily distorts the field like metal parts in furniture, a passing car, or nearby cell phones and computers. Geomagnetic sensors must first be able to see the different magnetic fields in order for the designer to separate earth’s magnetic fields and compensate for the distortions. PNI Sensor’s RM3100 eliminates any “blur” in your magnetic field measurements making distortion error correction a snap, and ultimately allowing you to easily and accurately calculate absolute orientation and heading of a drone or vehicle.

I share a little information that Jordi Muñoz comments about the new "mRo Location One GPS" that we are coming soon to launch.

For more information or questions please feel free to write me directly at help@mrobotics.io just mention me in the mail body ;) or follow us on our social networks at www.mrobotics.io

Best regards!

Pedro Matabuena
mRo Director
Twitter: @pmatabuena

[Jordi Muñoz]

"Can you see the PCBs that are side by side? Can you spot the differences?

The one on the right is an early prototype, it has a lot of holes(vías) to "clamp" the ground plane. The one on the left is clean! Why? Well, we are experimenting (sorry for keeping all the engineering fun). The left one is a new concept that uses blind vías which are drilled by laser on the inner layers (4 in total). This allows us to have a very clean ground plane, which leaves the cooper of the first layer free of "artifacts", and the ground is attached around the antenna pin -The ground plane shape and dimension is a fundamental component of the patch antenna-, the idea is to create a more predictable behavior.
This new GPS is known as mRo Location One and has build-in CAN. It also has the new RM3100 compass, the only one currently working and supported by Ardupilot (via CAN), this mag has extreme performance and we salivate every time we fly with it. We also added a "bump" to all of our GPSs, the bump is the little piece of land on the front where the magneto resides, an attempt to keep it away from all disturbances and boost performance.
This module is ready for mass production and it will be released with the new uBlox M9N, which has true multiconstallation support and higher refresh rate.




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  • @Edward, I have an MMC5883 on a breakout board ($10 from Mouser), and I am looking at the differences between the HMC and QMC drivers with goal of creating a driver from an existing one from those in Betaflight. They are fairly simple with only three functions.

    The Chinese IST8310, QST5883 are cloned from the actual dies from Honywell, so in effect they ARE the HMC5883. The MMC from Memsic is a clean-sheet creation and has been on the market for several years. Google Memsic.

    Won't ever get away from the use of mags since they provide a spatial reference on the Z axis for yaw; especially with no GPS signal..

  • Thanks Pedro!

    Thomas I just looked at the drotek site and theirs isn’t CAN based so that’s a step back from the MRO one but I hope there is an mro can only unit.

    As for the MMC5883, that’s pretty interesting except I’ve had nothing but problems with the hmc and qmc variants. Is the mmc driver compatible as well? I can’t find anything about it except a google search shows someone one a betaflight git page saying the registers are in different locations. None the less, it would be interesting to see but I’m hoping the rm3100 will simply be less susceptible to magnetic disturbances simply because that’s what most of us suffer from when space constrained.

    Appreciate the info on the MMC. Would really like to try or see some data on it. Just whatever it is, I’m hoping we can step away from the the issues ever present with the hmc units. My real hope is some type of gps/ins system... no more mags please.
  • Not to be a kill-joy, but the induction-coil based RM3100 has been on the market for a few years. Drotek has a $40 self-contained module for drones.  In fact, the coil based RM3100 sensor is a step backwards in technology. It adds an order of magnitude in complexity and cost (requires a 200khz excitation circuit) to what is now a very elegantly solved problem that was/is solved with the latest cheap (i.e., low-cost) MEMS sensors.

    (Note: Three types of mags (compasses) being discussed here; AMR [magneto-resistive], induction-coil, and hall effect)

    A better choice for magnetometer in drones is the MMC5883A AMR(magneto-resistive) part.. Compatible with the HMC5883 which is also an AMR sensor. I have my compass mounted in the center of the quad-copter (NO it is not on top of a stick[dumb idea when the copter crashes]) and I have NEVER had an issue with it.

    For higher reliability (and for those 0.9999ers out there), one can use a hall effect compass in conjunction with the AMR (MMC5883A)) compass for extreme reliability; a much better and cost effective solution. The issue of AMR compass' magnetic field "flipping" can be solved by validating output data with known calibration data and by using a hall effect compass (immune to flipping but less accurate/resolution) in parallel.

    (Note that is takes a pretty strong magnetic field to "flip" an AMR compass)

    The MMC5883MA is an evolution of the (discontinued Honeywell HMC5883 but cloned by IST in China[and others][actually Honeywell SOLD OFF the HMC5883 manufacturing technology to China (who says China STEALS our technology. We GIVE it away!) ]). The MMC5883MA by Memsic, which has been on the market for several years, is an order of magnitude better and even pin compatible with the HMC5883. Ironically, Honeywell is trying to sneak back into the mag component business after seeing the glut of flourishing Chinese clones of THEIR old product!

    Drotek has come out with a compass module using the RM3100 for $40.

    "Blurr in the magnetic field"?! All magnetic sensors have the issue of hard iron and soft iron interference, and the RM3100 doesn't eliminate them any better than existing hall effect or magneto-resistive sensors.

    Comparing the RM3100 to a hall effect sensor is no comparison considering the hall effect has the least accuracy, nor is comparing it to the ubiquitous HMC5883 design which is about FIFTEEN years old.

    As a suggestion, mRO, drop the RM3100 and use an MMC5883A....

    Happy flying; in the RIGHT direction...

  • Hello Edward, this are the dimensions for the mRo Location One GPS. We will soon release a document that answers all your questions. Stay tuned at mRo blog.

    Best regards!

    Pedro Matabuena
    mRo Director
    Twitter: @pmatabuena


  • What are the dimensions, price and will this work with PX4 and Ardupilot? Are there any log comparisons of the RM3100 vs any other mag to look how much better the RM3100 is? Have you noticed (anecdotal or otherwise) if this mag is much less susceptible to disturbances from being in close proximity to battery lines (high current)? Also, are there plans for just a can based rm3100 or gps/ins?

    This is a great development. Been looking forward to something like this for awhile. Looking forward to some more info!
  • Thanks Pedro!

  • gostaria de acompanhar os testes....

  • Sure!... let me look into my files and I will shortly send to you :)

  • Nice!  Is there a .STEP available so us CAD obsessives can package it in our UAV obsessions?

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