gps (3)

Hello DIY’ers!

I stumbled upon this 2015 post from Gerard Toonstra and am looking to build a similar setup:

https://diydrones.com/profiles/blogs/cheap-1-2cm-scale-accuracy-for-your-surveys?id=705844%3ABlogPost%3A1974405&page=1#comments

There’s a ton of useful information in his post/blog, but since several of the links have now aged and technology has advanced, I thought I’d create a new thread on the topic.

I have a Phantom 4 Pro which I have a few years of surveying experience with (I’m not a licensed surveyor) doing aerial mapping and using Pix4D, so that part's covered. What I don’t have is $30k for an RTK unit lol.

I'm looking to build five small GPS "boxes" to place on my GCPs in order to increase the relative accuracy of my maps in all three axes. After a few days of research, I have a better understanding of how to build said boxes, but not enough to pull the trigger on the required components yet. Here’s where I’m at:

 

  • Accuracy:   Relative accuracy is more important than absolute accuracy in my case, at least for now. I’m shooting for sub-20cm accuracy after letting them log for 1-2 hours and processing using PPK. Getting down to sub-10cm without needing a base would be awesome, but I’m not sure that’s realistic.
  • Arduino+Shields vs. Raspberry Pi 4:   I don’t have any experience with either option. I plan on getting familiar with one or the other so I can build these boxes now as well as a mapping UAV in the future. It seems Arduino+Shields is the simpler and cheaper route, but I like how the Raspberry Pi 4 comes with so much capability packed right on the original board. I’d happily pay the extra money for the Pi if it makes sense for this project. If I go with the Pi 4, is 2gb enough memory or should I go with the 4gb version?
  • GPS Module:   Although the ZED-F9P claims to be around 1cm accuracy with RTK, it seems a bit overkill if using it for static logging and PPK. As for cheaper GPS modules I'm looking at the M8N or M8T, unless there's another capable/cost-effective module that I'm unaware of.
  • Usability/IO:   I'd like to be able to have my settings saved for the boxes instead of configuring them before each job/flight (EEPROM?) so that I just flip a switch and they eventually start recording until I turn them off. A few LEDs (or mini LCD screen) to indicate battery charge and satellite fix/data activity.
  • Runtime:   Battery operated, rechargeable. If I had to let them collect for let’s say four hours would one or two 18650s do the trick? AAA’s? I’ll likely be logging at 1Hz.
  • Communication:   Do I need antennas for them if they’re not communicating to one-another?
  • Data Storage:   Stored onboard each of the boxes. I assume via SD cards.
  • Programming:   I have a little coding experience, I’m sure I can learn what’s required.
  • Enclosures:   I’ll model and 3d print them.
  • Random unknowns:   Data Logger (Arduino + Sparkfun Logomatic v2? Do Raspberry Pi’s already come with data logging capabilities?), Software (u-Center looks nifty, not sure if that’s needed for PPK though), Data Processing (RTKLIB? RCTM?).
  • Budget:   A few thousand USD, I realize that generally speaking higher accuracy = more money.
  • Working Location:   NW United States.

I know this is an absolute mountain of questions, many of which are subjective, so any spattering of info would be greatly appreciated! I’ll be sure to share my build-in-progress and performance of the boxes here in case others find it useful. Thanks!

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Meet the new mRo GPS Family. The next gen...

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The mRo family of GPS sensors are one of the most powerful and sophisticated satellite signal sensors in the unmanned vehicle industry which we manufacture in United States. These have specially designed to obtain with high precision the position, velocity and timing information that the vehicle requires.

mRo GPS sensors are used by the best aerospace research and development centers and large drone manufacturers around the world. Available in different sizes and architectures to obtain the best noise immunity, lowest possible weight and high sensitivity each of them includes a robust system capable of accurately detecting the different satellite signal constellations of USA (GPS), Russia (GLONASS) and Europe (Galileo) totally individually or simultaneously.

Our range of GPS sensors it is in constantly improving technology and are fully compatible with any of our mRo family of autopilots.

Download mRo GPS Family Comparison Table

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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.

-Jordi"

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