Servers by jDrones

Basics needed for a rover with RTK GPS?

Just staring to put together a rover but no experience with RC or ardupilot. Have electronics and moderate PC experience - windows and linux.

Have a local CORS station and have signed up for free access so no need for a base station.
Looking at using the F9P GPS module although open to others.

Will probably be piecing this together over time since I have limited time and budget. Trying to understand what parts I need to put together and a bit overwhelmed by it all.

Am thinking I need:

Servo for steering (conventional vehicle steering)
relay channel for emergency shut down
GPS module and antenna
base to rover link (Looks like there are some $30 options with decent range - need about 1000 ft)
NTRIP client - a raspberry pi board? CORS data will come through wifi home network
Rover controller - Pixhawk 4? This is for a mower so only moderate response speed is needed
Mission planner on laptop

It appears there are several ways to hook the various blocks together. Are there some block diagrams showing the various blocks and the connections between them?

As a first step I was going to get the connection to CORS going and just verify I can receive the corrections on a pi or PC. Not clear to me what program to use for that…

Hi Jim,
We have been in a similar situation to yourself over the last year or so.
I found the guide “First Time Setup and Configuration”
https://ardupilot.org/rover/docs/apmrover-setup.html
particularly useful. We just followed the steps outlined adapting it to our own vehicle.
Quite a bit of time spent browsing this discussion board also proved to be very fruitful for us first timers.

From our own experience I would strongly recommend starting with as simple a system as you can and then adding sophistication one step at a time and getting satisfactory results and gaining an understanding of what you have done at each stage before moving to the next. For example, I would recommend that you start off with a plain GPS and add in the RTK component once the standard GPS is working well.

We also found starting off with a cheap model radio control car to be a huge help. Crashes and run-aways and the subsequent modifications being easy to cope with on a small scale.

Thanks. Have a lot of other things going on so this is definitely going to be a background task for a while…

Any specific hardware you could suggest for getting started without putting a lot of $$ into it? If the parts were reusable on the larger vehicle that would be a plus.

The F9P is definitely a good RTK GNSS module - I have used many for UGV’s, base stations and rover poles. I use these: https://www.gnss.store/gnss-gps-modules/113-ublox-zed-f9p-rtk-gnss-receiver-board-with-sma-base-or-rover.html. If you are budget conscious then you can certainly do RTK positioning cheaper - especially if you have a companion computer that can run rtklib (such as an RPi).

Jimovonz, I had planned to have a RPi or something similar to run rtklib. I am a bit confused by the link you gave. It goes to a F9H board and states it needs a F9P board in addition on the vehicle. It appears that basically is 2 GNSS receivers on the same vehicle for precise heading info. I am looking to keep the cost down but not necessarily the cheapest. “Good value” is how I would put it. :slight_smile: What other options are there I should be considering?

In the vein of stepwise refinement I am thinking perhaps make an RC controlled vehicle first. Then add GPS, then RTK. A number of smaller steps in between but that’s the coarse overview. That would help me get the needed knowledge as I go.

My apologies - I was supposed to link to the F9P module: https://www.gnss.store/gnss-gps-modules/99-ublox-zed-f9p-rtk-gnss-receiver-board-with-sma-base-or-rover.html

The cheapest RTK setup I have used is the single frequency M8N along with rtklib. While this does work, it certainly is more susceptible to environmental issues and you will find that the amount of time you spend with an RTK fix is less than other options.

I have also used the NavSpark multi frequency boards: http://navspark.mybigcommerce.com/ns-hp-gn2-px1122r-multi-band-quad-gnss-rtk-breakout-board/ These do work well but are a bit more fiddly to set up.

I want to try PX1122R for RTK.
Could you explain more detail about “fiddly to set up”?
Do you have any results of module performance?

The “fiddly” bits I was referring to was soldering connections (including 3.3v reg) and using a patch lead to connect the antenna. The actual configuration once connected was fine. When testing this module I fed RTCM corrections in to the second serial port direct via an ESP32 running an NRTIP client and using the local wifi. I have not tested moving baseline yet but it is on my ‘To Do’ list.

Servers by jDrones