General Misc > Misc
First personal project.
Tommy:
I think I have just fallen in love with the new MK5 Tac drive I got.
http://www.invacare.com/doc_files/1114808.pdf
with linear actuators outputs, limit switch inputs, momentary switch inputs for directional control
,E-Stop Inputs the thing even has a tile sensor input. and best of all it has an external programing
unit that can be found on e-bay or craigslist.
This is one sweet drive, if it works (not powered up yet).
Tommy
Tommy:
Had some time to play with this project, and have come to the conclusion that this type project is very challenging.
The most challenging being the mowing. I hoped to have it mow straight lines as programed, that has not
happened as yet.
--- Quote ---Will two drive wheels and two casters give you the traction you are looking for to shovel snow or traverse a garden?
--- End quote ---
As i'v come to believe is stability is move important then traction(Feedback not on Drive train).
The first picture below is the original wheel setup(with the test mower installed).
The next one is an test to see if a fixed wheel in the back would help keep it stable on uneven surfaces, It
did work good after alignment adjustments. but it toke 4sec to raise and 4 to lower.
The last picture is a test to see if wider tires would help stabilize my Mule. It did work sweet, much faster
then raising and lowering a fixed wheel. While my mom's lawn is not to bad, my lawn which I'm using for
testing is very bad, complete with 30deg sloops,and drainage ditches(I should take the shovel away from my lover),
To my surprise the Mule spines even the wider tires when climbing 20deg on wet grass. So now I'm thinking about
adding a third drive wheel(replace the back casters).
Tommy
z.s.tar.gz:
With this type of project (especially as a first project) you're looking at a lot of work.
More importantly than any aspect of engineering is the idea that it will work. Maybe not today, maybe not tomorrow, maybe not this month. But it will eventually be finished.
Many people fall into a state of "permanent hold" when they come across a large roadblock after spending a lot of time on a project (myself being a prime example).
And after all, the journey is more enjoyable than the destination.
Soeren:
Hi,
--- Quote from: Tommy link=topic=11962.msig92079#msg92079 date=1285675277 ---To my surprise the Mule spines even the wider tires when climbing 20deg on wet grass.
--- End quote ---
With the mass being equal, the wider tires, while having a larger footprint, have less mass/square" of footprint.
There's not much difference between eg. 2 square inch of 10lbs/sqr" and 10 square inch of 2lbs/sqr" and if anything, the wider tires will slip more easy on wet grass if it goes at any speed beyond a slow crawl.
(Knobby tires or the like that digs in is another matter).
Perhaps if you pair up a combined drive wheel and lawn aerator...
Tommy:
--- Quote ---With the mass being equal, the wider tires, while having a larger footprint, have less mass/square" of footprint.
--- End quote ---
Soeren
While I can see the logic of the above line, there must be some variable overlooked. Because it seems like the new
tires draw @30% more current then the old tires, in my head I see that caused by greater friction between the
ground and tire, which may also be the reason it makes the Mule more sable on uneven surfaces(which is a good thing).
I don't have drive current feedback my only justification for the 30% value is by testing with different
motor drive power input fuses, like install a 10Amp fuse then perform a task that would make the fuse fail then
increase the fuse value until the task is performed.(gone through 3 boxes so far at @3.00 each box, seems I
should install feedback soon).
My next effort is to replace the 2 pole drive motors with 4 pole, in hopes of getting better low speed torque
in hopes of keeping the tire from slipping. it also gives me the opportunity to open up the gearboxes and
remove the lost motion before they are installed.
--- Quote ---Perhaps if you pair up a combined drive wheel and lawn aerator...
--- End quote ---
Soeren, if I installed something like the picture below, my mom would start to cry just looking at it.
and I wouldn't get too close either, these big testbeds can be a handful.
Tommy
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