Ryobi 40v Robot Mower With 40v Trimmer Whiskers By Jstarne1/ Starnes




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Ok so I am going to run over the general idea. I have been researching getting a robot mower and the options are sickly. They simply don't offer a full size electric robot mower for a reasonable price, at least for my pockets.:)
I didn't mean anything negative. I was just curious, given all the odds and ends purchases what you thought you had in it. Building something like this myself has always been an interest. A lot of DIY remote control examples can be found around but not many robotic / autonomous ones.
Oh no , I dont take it negative. It is a learning process. Learning costs money !
Ok so I stripped down the frame , cut off the footrest and removed the seat mount. I am using corrugated plastic to insulate the electronics from the frame. I wired the motor breaks to release on power up which means they will lock if I lose power.
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Update, Grr upset at the sabertooth.

I have been trying to use the Sabertooth 2 x 12 simplified serial mode with Ezb tiny and keep having an issue. For example I can click the forward arrow and the wheels roll forward. Great! check. Then click reverse and one wheel turns forward.... what the heck? Similar strange issue when left or right. There are only 4 terminals, so there are 16 possible combinations. So I swapped them around and wrote down the configuration as I go to make sure I had no repeats. I just got more crazyness. So I went back to the original wiring that worked on the forward command and swapped the EZB for a RC Reciever and swapped from Serial 9600 to RC servo input mode and it worked great. To be specific is was mixed control where one servo control is forward/reverse and the other left/right turning. So the only think I can think of is to do a Movement Panel with servos. For now this will allow me to work out physical build.

Any help is great! I need a Movement Panel working with the RC mode since serial is giving me an issue, or if you can think of what the heck is going on with serial.
I don't know if this will help but.......

Are you using one sabertooth for both wheels, one motor for each wheel and attached to a different channel on this sabertooth? Looks like this from your picture. I have this setup for the DC elbow motors of my B9 robot's arms. However I'm not using a Movement Panel but using EZ scripting to send simple serial commands to each channel to move the motors independently. I found that if I send the two serial movement commands for each channel to the sabertooth to fast that the second command to engage the second motor on the second channel won't run. I found that placing a short sleep command between the two serial movement commands helped the second serial movement command to get through. Hope that makes since.

Also (I haven't tried or confirmed this), but if you have two sabertooth's try moving the second motor to the other sabertooth. I have a feeling that one single sabertooth can't process the the serial commands as fast at the EZB can send them and causes the second command to get flooded out. If you split the motors to two different sabertooths then each one can process the command on it's own and as quickly as it's received. :)

Hope this all makes sense and helps.
So for 5.99 I picked up outdoor tires with a slightly more aggressive tread. The rim is exactly the same in size. I was able to swap them easily. The only thing that I am concerned of is that the original tires were solid rubber which didn't have much grip. This frame has a couple spots under the motors that are only about a inch or less from the ground. I am considering making cuts to raise the clearance tommorow.
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Ok after mounting the tires I took them to the gas station to air them up to 30 psi. They are nice and firm now and I believe these will perform better outside than the solid rubber tire.
Enjoying the updates!
Thanks DJ !
Oh FYI shortly after this project is running I am submitting it to The Home Depot/ Ryobi DIY competition, 2500 grand prize
So I want some more wiggle room between the front of the Jazzy and the back of the mower. This is to allow room for shifting with terrain.
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This is thick plastic , .25 inch I believe. It is he same thickness at the steel that was there for the anti tip wheels. I made them extra thick to compensate for being a plastic replacement over steel. I cannot flex this by hand. After dinner I will drill the holes and start bolting things together for an initial test in the driveway.
Ok it has been pouring ran from the tropical storm rolling through so I will do a quick test out on the back porch which is wet and slippery.

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I switched the Sabertooth to RC mode , mixed servo input. So one servo signal controls forward and back and the second controls left and right. These are mixed by the Sabertooth microcontroller.

Youtube video of the first attempt mowing with the bot

Points of interest

- there are no screws on the mower body for easy access at the moment which makes it bounce around a bit

-I am still using the 40 v battery packs but the step up converter is going to be installed to boost the voltage from the 24 volts to 40 volts for the mower motor. This will lighten the assembly and also consolidate batteries. two car batteries last a lot longer than a 5 ah battery.

- the rear of the mower is sliding accross the grass, I still need to make knotches in the mounts to adjust the height of the mower deck.

- I was using this in RC mode and trying to record as well.

- the grass was about 8-10 inches tall being cut down to 1.5 inches so the mower could not mow as fast as a normal pass would be.

- First person cam will be added so I can mow from inside the house.

Comments and suggestions welcome ! thanks
Lol, nice video. I like the fish tails it gets going so fast. What is your fail safe going that fast and not stoping in time for the cars going by?

Way cool mower. Thanks for sharing.
I have a remote with a dead man switch , if i let go it should stop and apply the brakes, but if that fails I get to figure out what kind of ticket they give a lawn mower robot for failure to yield, LOL