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 Robotics / Handy Board / 5518
5517  |  5519
Subject: 
Re: Robot base
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Tue, 16 Feb 1999 22:46:06 GMT
Original-From: 
Bill Richman <(bill_r@inetnebr.)Spamcake(com)>
Viewed: 
3202 times
  
If you're looking for a reasonably large robot base, you might want to check
out "Toys 'R' Us"; there's a battery powered kid's vehicle called the "Wild
Thing" at our local store for $149.  It's basically about a 3 foot diameter
cylinder about 1 foot tall, with a 6 or 8" motorized wheel under the left
and right sides, a battery, and a seat with some simple controls.  You could
bolt a computer in the seat, wire up a couple of h-bridge motor drivers, and
be on your way.  This would be particularly suited for an outdoor robot, as
it's a bit big and clumsy for indoors...

> 
>  Circular. It is harder to get stuck in corners with a round
>  robot. It is easier to build a bumper system for it.
> 
> > base dimensions:  9", 10" or 12" or larger
> 
>  10", that leaves you a circumscribed square that is the size
>  of a PC-104 type computer.
> 
> > drive train configuration:
> >  differential steering or combined drive and
> >  steering or front wheel drive rear wheel steering.
> 
>  Differential drive is the easiest to solve the inverse kinematics
>  for.
> 
>  One steered wheel and two driven wheels is the easiest one to
>  get to go straight.
> 
>  One combined drive and steering wheel is the cheapest to build.
>  (see the Hero-1, Hero-Jr)
> 
>  Three steered and driven wheels gives you the most flexibility
>  and benefit (see the CMU rover papers)
> 
> > drive wheel diameter: 2.75", 3" or 3.25" or larger
> 
>  3.82" wheels for the following reasons:
>    - Larger diameter gives better results over uneven
>      terrain.
>    - 3.82*pi = 12" circumference. 1 rotation == 1 foot
>      of travel.
>  Optionally 7.64" wheels
> 
> > base material: plastic, aluminum or fiberglass (PCB material)
> 
>  Plastic (Polycarbonate aka Lexan) and aluminum. Alum for
>  toughness and plastic that is easily worked, structurally
>  sound and reasonably light.
> 
> > accessories: turret, extra deck
> 
>  Extra deck that is a turret, slip coupler between the top deck
>  and the mid-deck for signals.
> 
> Anyway, it will cost about $300 to produce, it won't go up stairs and it
> won't include batteries and no one will buy it because it can't compete
> with a R/C on closeout from Radio Shack.  :-(
> 
> --Chuck
> 
> 

                                        Bill Richman
                                        incolor.inetnebr.com/bill_r
                                        (Home of the COSMAC Elf
                                         microcomputer simulator!)



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