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Discussion Starter #1 (Edited)
I have been building a lightweight field based rover to spray Dockens and possibly Buttercups in my hay fields. I would like to be able and let the bot loose in the field and do its thing spraying weeds day and night.

Hoping to find some time to complete the machine over the winter to hopefully test this spring in the UK.

Currently debating the use of an electric gear motor like a wheelchair motor or a small Honda petrol engine ie 3 to 5hp. Batteries are the future but you can get a Honda or Chinese clone for roughly £100 were as the batteries alone will be close to £500 and still will not provide too much run time.

Rear drive is an old motocross bike wheel.

I also have an old toro Greensmaster lawnmower I might use as a back up plan.
 

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Nice, can't wait for you to have it up and going with pictures:). Batteries are the future, but I agree Chinese knock off fuel powered is better suited right now. If you look around china has some bicycle gas conversion engines around 100 cad 50ish pounds. They might work well for you. Will try to get a link when I am near a computer.
 

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Cool! I've also started on same small concept. The thought of being driven over by the 4650 JD isn't very appealing. After all, the vehicle is irrelevant, its the software.



Am using an old hydrostatic ride on mower and turning it into a tricycle style - easy steering - with motor/transmission right at the back since there won't be a person on it for traction. Forward and back is a single actuator with position control.
 

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Discussion Starter #4
Nice, hopefully as more builds start to emerge we can share and discover a lot of ideas. Think it will be a good future if we can build and maintain our own bots instead of being at the mercy of John Deere and the like.
 

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Electric is a good drive option, we run small 3 phase motors with 1 phase generator though a VFD. Allows full fwd/rev & speed/torque contol direct from microprossor. No messy hyd and everything is cheap off shelf or from China.
For sprayer a VFD and electric pump gives full pressure control so no flow control valves required.
For steering an electric actuator with built in position sensor.
 

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Discussion Starter #7 (Edited)

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Nice work on the gear, what did you use to sketch it up? That would have taken me 3 times as long to desgin then the actual print time.
 

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Discussion Starter #9 (Edited)
Nice work on the gear, what did you use to sketch it up? That would have taken me 3 times as long to desgin then the actual print time.
Not as hard as you think, its actually a plugin inside fusion 360 that auto generates gear tooth profiles, really handy. I used this tutorial. Highly recommend Fusion 360 to make your designs, its currently free if you use it for your hobby or a startup that turns over less than $100,000 I think.

Fusion 360 also runs on the cloud, so if for example there was a project to collaborate on, everyone could have access to the project and modify their part of the design in real time.

 

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Nice, hopefully as more builds start to emerge we can share and discover a lot of ideas. Think it will be a good future if we can build and maintain our own bots instead of being at the mercy of John Deere and the like.

Someday, somewhere, someone will put a stop to farmers making their own, believe me. The biggest drawback will be liability. Someone makes one that has a glitch and kills someone, it will be game over. I wish I was wrong, but I can see it happening.
 

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Someday, somewhere, someone will put a stop to farmers making their own, believe me. The biggest drawback will be liability. Someone makes one that has a glitch and kills someone, it will be game over. I wish I was wrong, but I can see it happening.

Kind of the whole purpose of this thread though Kevlar. The 4650 is cool and all, but yup, that sucker will kill you in an instant, or a family member, or a kid. There was no way I would have it run at canola palooza without a buddy behind the wheel. Nothing went wrong, he just watched soccer all day - but omfg can you imagine that thing tearing thru the grounds driving over attendees and tents!!!! Just like drones, autonomous ag equipment will have legislation to make it near impossible. My thoughts anyway. As long as my tractor is the only one in Canada running around, no big deal. But as soon as seedotrun actually gets dusty in an actual field instead of just farmshows, things will change quickly.

I also think autonomous ag will be the financial ruin of at least a few companies, most probably thru liability. Completely agree.

Small bots I think are the real innovation, we just need to figure out uses for them - we are farmers and not university academia - which gives us a distinct advantage. At least when it hits you, you might only get a sprained angle or a bruise, not a funeral.
 

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We built this in college for a competition. The base is a powered wheel chair. And notice the wood box in the middle, that is the standard wheel chair joystick with a x and y motor mounted to it to control steering and forward reverse.

At the end it goes off path using GPS to find the last waypoint. It has sonar on the front to stop before running into anything.

https://youtu.be/TqU8pDFYy6I
 

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Discussion Starter #14
We built this in college for a competition. The base is a powered wheel chair. And notice the wood box in the middle, that is the standard wheel chair joystick with a x and y motor mounted to it to control steering and forward reverse.

At the end it goes off path using GPS to find the last waypoint. It has sonar on the front to stop before running into anything.

https://youtu.be/TqU8pDFYy6I
Nice bot Case. So I guess you wouldn't have used a physical steering angle sensor, like on the full sized tractors? How did you know what direction it was pointing in? Gyro?
 

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Discussion Starter #15
Some more rules for the project.

1. For a £2000 budget, someone else should be able to reproduce the vehicle.

2. No complicated machined parts or expensive parts scavenged from other machines bought cheap off eBay. The build has to be simple and repeatable so only parts that can be easily and cheaply bought now and in the future. Pillow bearings, New ATV wheels, New pit bike parts, box section steel, etc.

3. Laser cut or machined parts would have to be costed into the budget at reasonable cost, this knocks out expensive machined components like in rule 2. But laser profiles and simple lathe parts can work if they help simplify the build.

4. Designed to last 50 years with replacement of wear parts/electronics.
 

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Discussion Starter #16
Quick update.

I have pieced together a chassis to prototype with. Trying not to get too bogged down with making it perfect and instead trying to learn what works first. Gone for one wheel drive that is also the wheel that steers. Next job will be to get the motor mounted and figure out a quick way to get an potentiometer on the steering for measuring steering angle.

https://www.thecombineforum.com/forums/attachment.php?attachmentid=146501&thumb=1
https://www.thecombineforum.com/forums/attachment.php?attachmentid=146503&thumb=1
 

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Nice bot Case. So I guess you wouldn't have used a physical steering angle sensor, like on the full sized tractors? How did you know what direction it was pointing in? Gyro?

I believe we just got the heading from the yellow handheld GPS that was mounted up high, kind of like most GPS systems do today. Since staying on an exact straight line and heading wasn't critical we didn't necessarily need a steering angle sensor. We just kind of used a wiggle motion. My memory sometimes fails me that far back.
 

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gavztheouch, I checked out Autodesk Fusion 360 and I don't see a free option unless you are referring to the educational versions? I have been playing around with Onshape (which is free but limits the number of projects) but it's paid up price/yr is ~1000. Fusion would be quite a bit cheaper paid up anually vs Onshape. Perhaps you got in on a deal that has previously been pulled... KB
 
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