I am currently building a rather large rover to solve some problems on my ranching operation. The rover is the size of a small pick up and needs to drive with enough accuracy to stay on the ranch roads and go through ranch gate openings. It will run a route of up to 7 miles distance through the ranch. The terrain isn’t hilly but isn’t flat either and covered with mesquite trees. (Don’t know if terrain will affect how I build base station?). I am also using a Raspberry Pi companion computer and dronekit (paired with a Pixhawk 2.4.8). Eventually, the rover will run autonomous missions at scheduled days and times for various purposes.
I am having a hard time finding a clear description as to what a good RTK setup is for Rover. I have made a small rover using a regular GPS module with the Pixhawk. I’ll be honest, I am not super affluent in the Ardupilot system yet, but I am at the point where I need to figure out my RTK solution.
This is my first post/question. I am not positive what the rules are but I am willing to trade something for a quality answer. Like, explain it to me like I am in the second grade type answer.
The more simple the better. This is my last resort, I have spent hours trying to understand the documentation, googling, and looking at other threads but I still don’t quite understand what the different RTK options are and the hardware needed for each.
Any help here will be greatly appreciated and like I said, I don’t know what I can trade but I am willing to entertain something for informative help.
Thanks so much,
River
**Of course I will also share my project once I get it operational. So far you can visit this link to see how I am building the rover: https://www.youtube.com/watch?v=abd7W_JdROI This is not me but my build is using the same methods. I am using an old Toyota pick up that has been sitting out in the pasture for the last 20 years. I think this is a decent start for anybody wanting to build a large scale rover without breaking the bank.
Working on a large Rover for mowing but having other problems besides RTK. However, my RTK setup is working well so I’ll give it a shot.
I’m using an an F9P chip from Sparkfun for my RTK base. It is powered by USB and controlled by Mission Planner on the PC. I’m using the basic 100 mW mRo 915 MHz telemetry radios most folk use also USB powered and controlled by Mission Planner but good antennas on the base and rover. Rover has a Pixhawk 4 autopilot with dual F9P GPS chips for heading info.
The RTK base antenna is @ ~20’ but I’m only having to reach out about 4000’ to the far end of the property. It’s flat land with no/few trees so telemetry in both directions is excellent.
For any range with these “line-of-sight” frequencies, height is key. If the antennas can’t physical “see” each other, you’ll need a lot more power coupled with good antennas. Don’t recall the brand antennas offhand but they are both small, fat verticals with about 2.5db gain. Is that 7 miles your max distance from the base? If so, I’m guessing you’ll need 5-15 watts (on both ends) depending on heights but that is just a guess. Also believe above 100 mW power puts you into FCC license range but would have to check into that. However, if you are in the middle of nowhere, likely not an issue.
This is great. Thank you so much. And no, I believe I can put the base in the middle so should be only 3-4 miles.
I’m curious, what other problems have you encountered with your large rover so far? I just finished building the rover portion, or most of it, enough to start adding servos next week. It’s all fly-by-wire even driving it manually. Check these videos if you want to see it: https://www.youtube.com/watch?v=pvJdk-n8Na8 , https://www.youtube.com/watch?v=kIEtDqVswo4
Those aren’t up to do date. That’s just as soon as I got it to drive. More videos to come as I add servos. Using a linear actuator with limit switches for the brakes and a regular servo for the throttle. 3-D printed me a little pot throttle for manual driving. Steering servo I made out of a CIM motor, a gearbox, and potentiometer with arduino. Fingers crossed it’s enough, it should be, it has power steering.
Anyways, thanks again for your feedback on the RTK. Have a great weekend!!
Sorry I took so long in this reply but have had some issues pop up that diverted my attention from the rover project.
Regardless, pretty cool set-up you’re working on! Looking forward to the final product.
My rover is giving me fits. Because of magnetic interference, went with dual GPSs for yaw data when stationary which is important with a mower making pivot turns. It’s been a tough road for me getting everything to work. After reloading firmware, checking/changing parameters for hours, etc. finally got the dual GPSs giving good yaw data while stationary without any flags yesterday. Was absolutely elated.
Today I fired everything up for a real run…and GPS data went away. WTH??? Still running traps without success.
What is the mission for your rig? Security or just a cool project?
So the link below is where I was about a month ago. The machine is taken apart right now as I am adding diamond plate to the “body”, building a flatbed for it, and painting everything.
As you can tell during this mission, if you pay attention, I switch to R/C mode because the compass does not like where it was placed. Going to put it on a tower next and see what that does. Will probably have the same issues as you but really trying to avoid $2,000 in RTK stuff until I prove concept a little better. Either way I am calling the progress I have a win.
The rover will actually carry the trip hopper. http://www.tsfeeders.com/ I will put it on a route to feed the cows. I currently have stationary feeders I built on a different ranch and they really take out a lot of the human error. Cows get fed at the same time every time and it really helps with overall management. Ie. I know what time all of them will be in the pen. They love those feeders. However, after a certain amount of head the stationary feeders get expensive, my pencil is telling me if I can get the rover to work it will make better financial sense because it is just one piece of equipment with the ability to feed more cows. Because it can dump feed in the proper spacing. Where the stationary feeders can only feed so many per unit.
Also, thinking down the line I could add a drone with a camera to the machine that will take off after each feeding and do a quick fly over the line it just fed, to get a quick video doc of what was there. Wouldn’t really be able to make out much but might be nice. Also, working on some gps collars using arduino IoT devices. Then programming an Ardupilot drone to fly to the coordinates. I think that would be handy for when heifers start calving. But these two ideas are a little ways out. I should have the rover back together and painted by this weekend. My grandad is coming in from California so I think its a good goal to have so he can see it.
To add some more uses to the rover, some of my friends said it might be good for game ranches and other livestock operations for feeding. Just a matter of mounting a different feeder on it. I also have a design for a large cotton seed feeder that could go on the back of it and since I am in cotton country that would be ideal for winter feeding the cows. Another idea was to build a hunting stand on it and run it on a regular route so animals like pigs and varmints get used to it. Then after a while, ride in it and send some pests to a dirt nap. But all that isn’t my focus right now. Just trying to get it to do the job I need it to do then go from there.
I noticed your videos on youtube were a real help as I was starting with Ardupilot so I really appreciate that. I hope to do a step by step build video series of the rover once I have it working well enough. Then maybe do some pre-builts for farmers and ranchers if they are into it but don’t want to build on themselves. I call it the Ranch Rover.
Thanks again for your input and I’m sure I’ll be reaching back out to the community as I get closer to dual GPSs and RTK myself.
Wow! You are making excellent progress. Nice rig! Is it fully 4x4? Should really be able to haul a load with the proper gearing/engine.
You have some great ideas for future projects. Drones and GPS collars make a lot of sense in locating heifers/calves. Really like your idea about a mobile feeder. Makes good sense to me. Ditto for a rolling blind. Surprised no one has thought of that one before.
If needed, really don’t think the RTK base will cost you that much unless you need a big tower to reach out. You also don’t need a big radio on the rover if you don’t have to monitor it continuously. But what fun would that be? Small amps and good antennas are relatively cheap. I’d make it so I could. Looking forward to your results mounting the compass higher. Let’s stay in touch!
BTW, where do you call home? Pretty country. I’m in S. Louisiana. Doesn’t look like that!
Thank you sir. Yes 4x4 if I lock the hubs. It’s an old 80s model Toyota Tacoma pick up chassis. Honestly just one that has been sitting in the pasture for the last 20 years. I like the low gearing ratio 4 low has to offer. It’s a 6-1 reduction, via chain and sprocket, before it goes to transmission. I have a 6.5 HP Harbor Freight Predator engine on it right now but plan to upgrade to the 13 HP, especially because it as a built in electric starter. It will actually only need to run a mission at 3-5 mph so it shouldn’t take much but I also want to see how much of a load I can get on it. Just ordered some airbags for the rear suspension. Also, if I can eventually raise enough money I’d really like to build an electric one, especially for that rolling blind idea.
Okay, I’ll look some more into the RTK stuff. I just figured the easiest thing to do would get a kit from Ardusimple. Which I think only came out to $1000 - $1500. I’ll look more into it. I think I will need a big tower though. I am looking about about 3 miles from the center of loop. Honestly, just need to force myself to get back behind the screen once I get the build done. Got some coding to do too, so I guess it’s about time for another week in the cave.
Home is Haskell, TX. North of Abilene by a few counties.
For sure on keeping in touch. Hopefully I have a video posted of the completed “proto” by at least next week. Spent the last 3 days pulling it all apart and I think I have everything cleaned up enough to paint. Have to check cows tomorrow so should paint Thursday, reassemble Friday, and run a mission Saturday, fingers crossed. Won’t have the feeder on it until next week though.
Thanks again for sharing your wisdom
Also maybe it wasn’t your vids on youtube. Either way I appreciate your help so far! haha
Looking forward to seeing that animal rolling! Fun build. If you feel confident about the project overall, might consider springing for the 23 hp Predator. Know it’s about double the cost ($400 vs $850ish), but think you will be happier in the long run when you get it working with a load. Also has an oil cooler which should be nice in summer and you can cover it during cold weather runs.
Did you teach yourself coding or is this just an interest? Either way, you’re way ahead of me. After I get the initial bugs worked out on mine, I might need some coding done (mowing logic) and will be willing to pay for your time.
Need your snail address. Have something that may help.
Gearbox is whatever manual transmission was part of the old toyota pickup I made it out of.
This video is an old basic overview of how I did propulsion: https://www.youtube.com/watch?v=kIEtDqVswo4
I’ve had good luck with the Here+ differential setup - I’ve never compared pricing with the other systems.
Another thing to look at would be public or commercial NTRIP services. If there’s one suitably close, and you can get internet reception (at a ground control station), then it saves you needing your own base.
