KevinG's Autonomous zero-point turn Lawn Mower

@SJohnson, this is a nice looking installation. These kind of pictures encourage me to work on my rig.

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I have the servos @Swebre suggested on order and per @Yuri_Rage’s suggestion I ordered the Matek H743-Wing and am ordering 3 simpleRTK2B receivers. I have been reading through this thread (again) along with several others and have learned a lot albeit just scratching the surface. I was watching one of @ktrussell videos about gps last night which was helpful in understanding how the rover/moving base receivers work but I am struggling to determine how get the base station data to the moving base. I have seen suggestions for the MavLink and Xbee. Is there a benefit to using one over the other? There are a few objects that will make line of sight impossible. Can multiple antennas be used to distribute the signal around the property?
If anyone has a schematic of a complete system for a rover (flight controller, servos, GPS, transceivers, etc) that uses GPS-yaw they are will to share or a link to a resource that would be much appreciated. If one does not exist I am happy to post one for my setup once I am pretty sure I have it working and right.

The easiest way to get RTCM3 to the moving base is through Mission Planner. Connect your fixed base to the USB port of the computer, and MP takes care of the rest.

If there’s a public NTRIP station nearby, you can skip the fixed base and use that, as well (also in Mission Planner).

Skip XBee, in my opinion.

I like mRo’s 915MHz radios for a simple telemetry link to Mission Planner. It’s good to a few hundred meters and handles some minor obstructions reasonably.

Again, there is no one-size-fits-all solution to what you’re doing, so you’ll likely not find a comprehensive diagram. The Wiki is excellent for moving base config. I simply don’t have the time to create schematics, diagrams, and models of my one-off mower.

Jason here is a link to a post written by @ktrussell when he was helping me decide how to inject my RTCM correction signal from my base station.

There are 2 choices. You either run the corrections through your computer and Mission Planner or you send them via radio from your base station to a matching radio connected to the GPS unit. I went the radio to radio link avoiding the need to always have my computer hooked up for it to work.
The other method is probably easier and is what most people use.

Hey Jason - I use a fixed base GPSplugged into my PC in the shop running MP and sending corrections over a telemetry link using two cheap mRo 100mw SIK radios (same as Yuri) but with a good antenna on the rover and on the roof of the shop. Rover can wander all over the 100 acres without loosing telemetry (~2600’ max). Signal gets weak but stays active. I’d try those radios first. Any issues, there are several 900mw radios out there but they are pricey. Antennas, good coax and elevation are key to range.

I have successfully used many methods for RTCM3 injection. The easiest by far is just a radio link through Mission Planner.

I’ve used, in no particular order:

  • 915MHz radios via MP
  • A WiFi connection through an ESP32 (both with and without MP)
  • Both of the above methods via a fixed base station with a Raspberry Pi WiFi repeater (TCP connection to MP)
  • ESP-Now (ESP32 specific 2.4GHz protocol), directly to the module
  • NTRIP through MP

I’m also familiar with but have not used a LoRa configuration similar to the way I used the ESP32s.

And, at present, an SIYI HM30 unit that provides video+telemetry+redundant RC, using Mission Planner and a local NTRIP station.

All worked equally well with respect to reliability (within their spec’d ranges). The SIYI HM30 unit provides the best range I’ve seen so far at an increased pricetag and some added complexity. I also really liked the ESP-Now method, but it may be a bit range limited for some applications.

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I have used long range RFD 900+ radios through Mission Planner for years and they work great. I am in process of converting the setup this year because it became annoying to have to run Mission Planner just to mow the lawn. The new setup will use the RFD 900 for direct base station to rover gps corrections. I have simplified my rover gps setup as well by installing a Septentrio with heading. In testing it doesn’t seem to locate any satellites while indoors where the F9Ps would locate dozens quickly. Outdoors, the Septentrio finds satellites quickly and starts reporting heading immediately. I haven’t tested RTK yet, hopefully this week. I will add a second short range telemetry radio to the mower for testing, ardupilot updates, and log downloads.

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Hey Jason - Something to keep your interest going through the frustrating times ahead (at least was/is still is for me…) This is one of my mowing patterns with 690 waypoints covering 9+ acres around three buildings. Total distance traveled will be ~17 miles. Onward!

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On another project, I’ve been using a SimpleRTK3B+Heading board based on the Mosiac 5 module. It’s very expensive but certainly convenient!

Unfortunately, it had an unexplained failure, and I’m awaiting warranty service/replacement via ArduSimple. They have been great so far.

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@Swebre, thank you for the encouragement. 9+ acres at 17 miles! I know you feel my pain when it comes to seeming like your life is spent mowing grass. I am working on this project with my 13yo step-son. I feel like this is a good project for us to bond on and eventually be able to spend time together on other things besides mowing grass!
The linear servo you recommended arrived yesterday and fits absolutely perfect. I am unable to test the force of the servo but I suspect it will be just fine so thank you for the recommendation.
I was struggling with understanding how all of the parts connect and for that matter what parts I should be looking at.
I know there are no 2 configurations that are the same and I understand @Yuri_Rage reminding me of this.
If I understand at least one of the configurations it goes something like this…
GPS/GNSS antenna → GPS/GNSS receiver (ex simpleRTK2B) → PC running MissionPlanner → telemetry radio TX (ex mRo 915Mhz) → telemetry radio RX (ex mRo 915Mhz) → GPS/GNSS receiver (ex simpleRTK2B) → GPS/GNSS (ex simpleRTK2B) - flight controller (ex Pixhawk) → servo(s). I know this is a very simplified example that I hope someone can confirm or correct me if I am wrong. I have purchased parts based on the simplified configuration I listed so I hope it is at least close.

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Hey Jason!

Close…. Telemetry receiver on the rover connects to the flight controller along with the gps, servos, and power source (BEC). I am using different gps’s and my Flight controller (and yours can) will feed RTCM back to the gps.

Give a shout if needed and I will help if I can. Too many options for this to be simple…

Onward!

-Steve-

Steve Webre
Church Point, La
337-349-8365

Steve, thank you so much for reviewing my posts and helping me understand how the different components connect! I will very likely be calling you later this week as more of the hardware I ordered starts showing up. If I lived closer to Louisiana my step-son and I would stop by to see your rig in action!

Jason Miller

You can direct message also within the forum just as easily. If the design is your own, and you want to share it, I don’t see why you can’t post it or host it on a site like GitHub and link it here.

I found a number of designs right here on the Ardupilot website last night under the different flight controllers while looking for how to configure Ardupilot/Mission Planner for a rover. Thanks to these high level designs and help from others I have a better understanding of how folks are connecting the different devices and somewhat why. Now if only I can figure out why MP is telling me the Rover FW is loaded but copters are the only frame options I have available. Looks like more reading, Google, and YouTube research. I installed MP V1.3.77 and arduRover V4.1.5 if anyone has any ideas I could use the help.

I’m not sure where you’re trying to set frame type, but the default setting for Rover should work just fine (I.e., don’t mess with it).

Well I am working on activating the mower GPS systems and I have made some changes based on what I have learned, I have decided that I am not using the Simple RTK2Blite board and I am switching over to using to full size Simple RTK2B boards. While I am waiting on the second Ardusimple board to arrive I started trying to implement the single GPS RTK board with it being fed the RTCM3 signal from the base station. It is still a work in process but I am not done yet, There are several bits of good news even though it is not working yet, The base station is transmitting the RTCM3 correction signal over the x-bee radio attached to the side of the Ardusimple board perfectly and received on the x-bee radio on the rover Ardusimple board (according to the flashing lights on the board). However, the Ardusimple GPS board is not communicating with Mission Planner yet. I think I have it corrected right, even though I have soldered wires to the Ardusimple board, since I did not have a connector to match the one on the board. That connector has thrown me off a bit. I have several Orange Cube cable sets, cable building kits for the GH1.25, and nothing in my stash would fit the connector on the RTK2B board. Here is a picture of the connections. Mission planner acts like nothing is plugged in. I could have it wired wrong or have it not configured right. I bought this board from ArduSimple pre configured, which was probably wasted money. I also noticed there is another UART on that board, maybe I am wired to the wrong one. It wouldn’t be the first dumb mistake I have made. Maybe I just need to slow down and configure this board on U-center.


Sat antenna
Test setup

The labels on the SimpleRTK boards are a bit counterintuitive. Connect board TX to autopilot TX and likewise, RX to RX.

The “Pixhawk” connector should be a standard JST-GH, as well, wired using the normal Pixhawk standard.

Do I need to use u-center to set a certain baud rate on the SimpleRTKB board. Since I am not going through Mission Planner with the RTCM3 signal I don’t know how many parameters are set for me. I’ll go switch the wires right now and test. I have not set any baud rates.

Highly recommend using GPS_AUTO_CONFIG instead of uCenter. I think all ports end up at 460800 that way. Set GPS_DRV_OPTIONS=1, and then match the baud rate with your external RTCM3 source.

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GPS_AUTO_CONFIG is currently set to 1
GPS_DRV_OPTIONS are set at 0
image
I have switched the TX and RX wires to the GPS board with no change, I have also made up a cable with the GH1.25 connectors on the end and tried that option. So far Mission Planner always says GPS: No GPS

The board is powered up and the GPS FIX light is flashing
and the XBEE>GPS light is flashing.

I am sort of stumped but I will keep trying to figure this out. It will get figured out. I also have a new set of cables arriving from Ardusimple in a few days.