We are having a “gathering” here on the farm for anyone interested in learning/building autonomous Mowers/Rovers/Boats/Drones, etc. The main goals being to meet, compared ideas/best practices and share experiences with putting these things together.
We should have at least 5 working mower examples on hand and everyone is encouraged to bring their own. We have ~100 acres of short hay fields to play with so room to roam is not an issue. Will also have our on-site RTK (via NTRIP) active and available for use.
Logistics:
Church Point is a small town about 20 miles NW of Lafayette, LA with no motels. However, Lafayette is a large metropolitan area about 30 minutes away with many motels and a large, full service airport served by American, Delta and United. RV’s are welcome but please call for details.
If attending, please contact so we can plan accordingly!
Location Address – 1529 Beaugh St, Church Point, LA 70525
Contact: Steve Webre – 337-349-8365 or “swebre@hotmail.com”
I think you’re on the right track with NTRIP/RTK, and 14 miles is a reasonable distance for the fixed base (though near the upper limit of what’s supposedly acceptable).
I disagree that skid steering is always superior. For mowing long, straight stretches, Ackerman steering (or at least a presentation to the autopilot that mimics it) could be very successful if not preferable. The Rover firmware does an excellent job of managing “traditional” steering. There are many flavors of small to very large ag vehicles using variations of that Trimble steering setup with a great deal of success, and I see no reason why it shouldn’t work just as well with ArduPilot so long as the motor/steering wheel interface is well executed. Look up “AgOpen” for some examples - there are a solid handful of YouTube videos showcasing it.
You mentioned being concerned about a zero turn keeping straight lines due to the length of your paths. ArduRover works to keep the vehicle on the line, not aimed toward the waypoint. So, no matter how long the path, ArduRover will deviate about the line, not get off and then aim straight to the waypoint from that off-the-line point. So, I don’t see that the length of the line would matter.
I can see Yuri’s point about an Ackerman style vehicle holding steady, perhaps better than a zero turn. I think whichever you choose will work. There are several of us successfully mowing large areas with a zero turn. I hope to try Ackerman one day, though. I’d go with whichever you think will be more reliable to automate if you have both available.
As far as that RTK base, I have used a base located 36 miles away with great success. On only a few occasions did I see a missed streak of grass that I felt was because that distance. You should be golden at 14 miles.
I hope to see you at Steve’s place in a couple of weeks!
Jeff - Our 60” zero turn mower, running a 6” overlap spiral pattern, routinely holds under 1” variation running up/down our 2400’ runway. As to which type is better, a longer wheelbase vehicle should be inherently more directionally stable, but not guaranteed. Many factors involved but the key is proper tuning. I’m sure you can get either steering type up to your standards.
Hi Jeff,
I’m currently mowing about 25 acres per week, including a 2,000’ airstrip with a converted Badboy 72” diesel. All the advice you’ve gotten sounds right. Either steering system should work fine, once tuned. I’m running 6” overlap and rarely see any stripes. On smooth ground, it’ll stay less than .1 meter cross track error (4”).
Come to “Mowstock” at Steve’s place and you’ll leave with all the information you need!
Since these start life with radio control transmitters just like those used for copters, etc. Our biggest issue is with vibration at the moment. We have shock absorbers in the Pixhawk and on the module box, but it seems like it is still and issue.
Between those tracks, the “floating” engine/blade assembly with a single cylinder engine and the crappy blades, these mowers vibrate like crazy. Balancing the blades and removing any slop in the linkage will help tremendously. So would a heavier cutting deck. Are you modifying them for throttle control and remote start and kill? Nice safety features.
The smaller ones are manual start and throttle. The bigger ones already have start and throttle on the control Transmitter.
The tracks are pretty stable if you do not over tighten them. We are mounting our Control Modules to the control panel on the back.
I was thinking of adding Rubber sleeves on the mounting bolts for the mower deck to better isolate the frame from the vibration from the engine and blades…
Have a smaller one that I use here on the farm for going into places I don’t want to. It’s a bit crude but a tank otherwise. Seems most use a simple 7 channel Micro?? RC system but don’t use all channels. Easy mod to add throttle and start. (Also eliminated the manual throttle routinely getting moved to idle when going under or through bushes and briars.)
Comment about the tracks was a reference to their tread pattern. When we move ours across any hard surface without the engine running, the whole unit starts dancing. A more staggered pattern would help but I have yet to find any…
I think your idea of adding the rubber bushings will certainly help! I’ll have to give that a look tomorrow.
What are you using for obstacle avoidance? One or two sensors? I am using one JSN-SR04T which is water tight and allows for stopping, but I want it the unit to figure out how to go around the obstacle. That is a two sensor requirement right?
I wish you were not all the way across the country, I would go to MowStock.
Make? Had to look… I was dealing with the Shandong Nuoman Engineering Machinery Co., Ltd. Seems many folks over there make copies with very minor variations.
I don’t have any obstacle avoidance on this tracked mower. Was in the process of sorting out a Lightware SF-45 Lidar on my other autonomous mowers but have little hope long term for it as it is not a sealed unit. Waiting for something better to be developed (i.e. totally sealed with a wide FOV) before putting a lot of effort into it. Will check out the unit you mentioned.
Too bad about not making MowStock. Some sharp folks planning to attend. We have a major airport not that far away… Just saying.
Very similar to your smaller one but a 19" blade width and a hood shaped as the larger. After running ours a good bit, have several suggestions you might want to offer them if they ask for dealers input.
