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[DPRG] DD1-1 Tank Chassis

Subject: [DPRG] DD1-1 Tank Chassis
From: Rud Merriam rudmerriam at gmail.com
Date: Thu Oct 16 18:42:17 CDT 2014

I have a lot of experience with the Wild Thumpers since I have 6 of 
them, maybe 7. Some are 34:1 and some 75:1 ratio motors.

The tires are high friction so have trouble on carpets and grass. I 
originally had the 34:1s but they would not turn well on grass so got 
the 75:1s but even they have trouble with a tight skid turn. What 
happens is the inside front wheel tips way down and locks the chassis 
from moving. That also lifts the outside tire away from the surface so 
it just spins. If I keep working with them I may try to find smooth 
tires to replace the existing ones.

- 73 -
*Rud Merriam K5RUD
* /Mystic Lake Software <http://mysticlakesoftware.com/>

On 10/16/2014 05:24 PM, David Anderson wrote:
> Charles,
> Nice base.  Here's a link:
> <http://www.pololu.com/category/88/wild-thumper-all-terrain-chassis>
> So you had to remove the center wheels to get it to rotate on carpet?  I
> would think the front and rear wheels are the ones that scrub side-ways
> in a turn, generating a lot of friction, and the center wheels operate
> more like a traditional two-wheel differential drive robot, driving
> smoothly around the radius of the turn.  But you find  it works better
> in that case as a four-wheel skid steered base?
> Interesting observation.
> best regards,
> dpa
> On 10/16/2014 05:03 PM, cthurston wrote:
>> Hello David,
>> I have a 6 wheel "Wild Thumper" and like it for most surfaces. It does not want to turn on the carpet, But removing the center wheels for now took care of that. I even found a guide online to change the motors out to ones with encoders. I put away my "tank drive" bot made with a pair of old Snow Blower threads a few years back as it tore up the yard too bad. Did work good on the beach sand.
>> Thursday, October 16, 2014, 5:42:05 PM, you wrote:
>>> Doug,
>>> Maybe OK for a table-top robot, but drive train looks pretty thin
>>> for anything else.  Did you find any videos of it actually in
>>> operation?  No suspension at all, and I bet the treads will come
>>> off in a turn on any sort of outdoor surface.  Might be worth 50     bucks to play with, though.
>>> I know you are constitutionally disinclined to spend money on a
>>> robot base (wink-wink-nudge-nudge) but considering the amount of
>>> subsequent time and effort required to turn any base into a
>>> functioning robot, the initial investment tends to fade away       pretty quickly.
>>> If you are looking for a pre-built outdoor base, you might look at  something like this:
>>> http://www.orionrobotics.com/Razor-4-Wheel-Drive-Robot_p_249.html
>>>    http://www.orionrobotics.com/Odyssey-6-Wheel-Drive-Robot_p_250.html
>>> Just a thought,
>>> dpa
>>> On 10/15/2014 03:22 PM, Paradug wrote:
>>> -All,
>>>       I was just surfing around on the web and saw an
>>> Instructable that was using a tank chassis that I hadn’t
>>> seen before. The chassis is called a DD1-1. It incorporates
>>> several interesting ideas and has a price that doesn’t seem
>>> to be out of line. The ideas that caught my eye were the
>>> built in motor controllers, built  in low res encoders (both
>>> located in the side panels), and the use of all thread to            set the robot width.
>>> I have attached the web link for one vendor.
>>> http://www.aliexpress.com/item/DD1-1-Tracked-Tank-Chassis-Caterpillar-Vehicles-Integrated-Speed-Measurement-Motor-Drive-Module-for-SCM-DIY/1637071468.html
>>> Regards,
>>> Doug P.
>>> _______________________________________________
>>> DPRGlist mailing list
>>> DPRGlist at dprg.orghttp://list.dprg.org/mailman/listinfo/dprglist
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