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Mowing Grass with four wheel drive (The test)

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Tommy:
Everything tells me four wheel drive would suck at mowing grass, but there may be a minimum turn radius
that could be used that would cause no damage to the lawn.

best way to find out would be to try it.

first image is of the test frame for this project.

Second image is of wheels that'l be added to the test frame.

currently on the test frame there are two 350W 24Vdc Motors with a 3 to 1 gear reduction and 18" wheels.
I'm adding two 1000W 24Vdc with 5000 cpr encoders Motors that are directly connected to 14" wheels.

Tommy

jwatte:
If the castors at the back of the bot are idle (not powered) then differential steering will probably not tear up your lawn. That only happens when you use four-weel-drive with differential steering.

Tommy:
 
--- Quote ---That only happens when you use four-weel-drive with differential steering.
--- End quote ---

And that's the plan, on the test frame(top picture) I'm removing the casters and replacing with
motor driven wheels(2 at 14"x 5"), and use differential steering.


front two motors are 60rpm max with 18" tires
back two motors are 160rpm max with 14" tires

Tommy 

shimniok:
Cool project!

I vaguely recall a picture of a robo lawn mower years ago in a robot book that had omni steering or at least, all the wheels were connected with sprocket and chain so the wheels were always pointing in the same direction but could be rotated 360 ... I would think skid steer would be a bit tough on the grass too. And maybe not as great for minor course correction. What about ackerman steering? With rear wheel steer (or even 4 wheel steer, like 4x4 rock crawlers) for improved maneuverability. That should be easy to build right? :D

Tommy:

--- Quote ---I would think skid steer would be a bit tough on the grass too.
--- End quote ---
shimniok, I also have very little confidence that four wheeled skid steering would
be a practical configuration for mowing grass, the added power requirements(more batteries)
, and the damage to the lawn as just a few of the drawbacks.


--- Quote ---With rear wheel steer (or even 4 wheel steer, like 4x4 rock crawlers) for improved maneuverability. That should be easy to build right?
--- End quote ---
The test frame I'm using makes changing rear end configurations very simple(two bolts),
so testing ackerman, casters, two wheeled skid, four wheeled skid or and other types
should be simplified.

Tommy

     

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