Rover Lawnmower for Airstrip?

ArduRover
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Hey folks,

Apologies for another newbie lawnmower thread. I want to first say that I try to be very conscious of everyone’s time and have spent a fair amount of my own trying to understand before bothering everyone. I’ve reviewed Yuri & Kenny’s videos, browsed the forum a little, reviewed the ArduPilot tutorials, etc. I am hoping you will permit me a few elementary questions to help me better understand the bottom line capabilities so I can make sure I have reasonable expectations.

I have an airstrip and some open fields that I currently mow; adds up to about 15 acres of ground that is open with only a few obstacles to consider (runway lights mostly). I currently use an old International tractor and a batwing mower to mow it about once a week, and while that is considerably faster than the 60” zero turn I was using previously, I do find myself spending a lot of time mowing. My wife and I have 3 young kids so I’m hoping an automated mower will help me shift how I spend some of my non-working hours.

I spent some time working in the unmanned aviation field and took a lot of that for granted instead of learning the real mechanics of it all. We had an autopilot module and RTK module on the aircraft, and a ground station with directional antenna (to update waypoints real-time, send payload commands, etc). It was all very seamless as it was a fairly established system at the time, but I never thought about how it all works.

First question; This station is about 14 miles from me:
https://www.pagis.org/index.php/data-resources/reference-station/. I don’t truly understand what sort of information I’m going to need to be able to receive for reference, but this station has a Trimble Alloy GNSS Receiver and it says they’ll provide no-fee RTK. I would assume this would get me going with a high level of accuracy, right?

Second question; getting this all to interface with the mower controls is the part that I’m having the most trouble understanding (the autopilot outputs, giving the autopilot information, controlling servos, etc). I’ve read about disconnecting the gas-shock dampeners on the zero turns and using servos to move the control levers at or near each individual wheel pump. What about on a mower with a traditional steering wheel? Trimble makes a product called EZ-Steer that is basically just a motor with a thick foam/rubber wheel on the shaft that rests against your steering wheel and provides the steering (see pics for context). Has anyone tried anything like that, or is the zero turn method the least difficult? I have a nearly new zero turn I don’t mind using for this project, but I was curious if a different style might be more appropriate. I don’t usually make any pivots turns when I mow it now. I just make loops around the entire thing, starting in the middle (the middle is paved) and then mowing in ovals that increase in size with each path. I wasn’t sure how well these handle shallow arcs, or if they have to be pivot turns because of the waypoint to waypoint nature of this.

I don’t want to be a burden that has to be dragged to the finish line on this, I just need a little help with the big picture thinking on the front end.

Thank you all in advance!

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I’m far from an expert on the Rover side of ardupilot, but I have suffered some ardurover usage.

I think a zero turn is going to work a lot better, it’s just simpler from the autopilots point of view and easier for it to hit the waypoints it’s aiming for with a skid steer configuration.

As far as how to mechanically interface with the controls, that’s going to be very specific to your mower and I would say if you don’t have a good mechanical intuition I’m not sure I’d recommend attempting it (not saying you don’t, I just don’t have really specific recommendations beyond what you have probably seen the others do).

I also suspect that Trimble unit is going to have issues with slippage on something that doesn’t have power steering.

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Thanks Mark! The more precise control of the zero turn makes sense as far as hitting the waypoints, I hadn’t really factored that in. Each mow consists of about 40 parallel offset passes, each about 2,500’ long. My “turnarounds” are usually large sweeping arcs versus J-turns, or pivoting in place so I can minimize turf damage. Perhaps I’ll just look for less aggressive turf tires and go with the commonly accepted approach. I just worry about my zero turn being able to effectively track straight on half-mile straight line runs, both from the output differences inherent to independent wheel motors and GPS error. It appears those parameters are all adjustable so I’m sure I could get acceptable results after some trial and error. Thanks for your input.

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Jeff - Make it to “MowStock” in two weeks and we’ll have at least 6 different working mowers on hand, 4 of which mow runways. It will be held here at 71LA (2400’ good grass). You’re welcome to fly in. We can answer lots of questions on site. Smooth Air!

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Steve; I’d be very interested in that. Can you give me some details on the dates, times, contact info?

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MowStock - April 21-22

Mower/Rover Folks!

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.

Several folks from the Ardupilot Forums and YouTube fame will attend including Yuri Rage (Yuri’s Homebrew & DIY - YouTube) and Kenny Trussel (Kenny Trussell - YouTube).

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”

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Thanks Steve, I sent you an email.

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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.

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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!

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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.

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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!

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Where in the world IS “MowStock?”

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3-4 posts up. All details…

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David - Found the info?

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We are doing similar things with UVG mowers at https://smartertools.us/

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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.

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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.

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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…

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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.

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What make is your little crawler?

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.

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Hey Patrick!

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. :slight_smile: