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In lugnet.robotics, Tobbe Arnesson writes:
> In lugnet.technic, Roy Nelson writes:
> > I've finally posted pictures of my RCX Tank Base:
> > http://www.brickshelf.com/cgi-bin/gallery.cgi?f=28951
>
> <<snip>>
>
> > This was a good alternative to using an adder/subtracter device to
> > acheive straight driving.
>
> Why didn't you use a adder/subtracter?
When I was first designing the tank base I had assumed I would have to use
an adder/subtractor to have straight driving. I spent a fair put of time
playing with different A/S trying to fugure out which would be best to use.
It was then that I realized I didn't want an A/S. An A/S uses one motor to
drive forward/back, and the second motor for turning, this only gives the
power of one motor to drive over obsticles, I wanted the power of both
motors. I thought there might be some other arrangement of gears and
differentials but that is way beyond my mechanical ability so I posted the
probelm on Lugnet. Dean Hystad suggested a clutch that linked the left and
right drive axles. It worked almost perfectly and only takes up the room a
couple gears and an axle. The clutch did have to be overcome when turning,
reducing turning effectiveness. My second RCX tank base uses a 'ribbed
hose' style of slip clutch (as opposed to a white 24 gear clutch) and it
works much better as it requires less force to overcome it.
>
> > ==>"Droid Developer Kit squeeze and lift" style hand. The hand was able to
> > lift about half a can of pop. As you can see in the pictures a full can
> > of beer caused the base to be lifted.
>
> If you mount the RCX and motors further back from the hand it will act as
> conter weight which should allow more lift load.
The goal was to position the motors as low and as far back as possible to
allow the RCX to rest as-low and as-centered on the unit as possible to
distribute the weight evenly over the tracks and to prevent tipping
backwards. I did have two Lego 'weights' on the very back to help
counterbalance it. As it was the power of the hand was at it maximum, even
if I had more weight on the back the hand would not be able to lift more.
>
> > ==>Skid steering was difficult for the power of the motors on carpet. The
> > combined resistance of the slip clutch and friction between the treads
> > and carpet put significant stain on the motors.
>
> If you remove the 1x4 plates on the treads there will be less carpet friction
> and thus better turning capabilities. Skid steering is a balance between
> skiddin' and traction.
Without the 1x4 plates there is too little friction - the unit was unable to
climb over anything without them! Plus the 1x4 plates raise the unit up a
little, make the tracks wider, and gives the base a much 'meaner', more tank
like look. The biggest draw back to the plates is they pop-off on a
regularly. I'm thinking about using some non-permenant/washable adhesive to
keep them on the new version. I have no idea what to use, any suggestions?
> > I am currently working on an RCX Tank Base Two that is bigger with better
> > suspension, easier-turning different style of slip clutch, and some sort
> > of cool Robot Warriors style of weapon like a chopping axe (which I have
> > no idea yet of how to build).
>
> 'lookin forward to it :)
The new base is mostly done. It includes a front touch sensor (located
behing the front curved bumber, similar idea to Sypbots). I intend this one
to be controlled by the remote and to be autonomous. I'm currently working
on the mechanism of the chopping hammer. Unfortunately I know no one in the
Calgary area how is also into Lego RCX robots who might want to have a
little battle.
Thanks for your response,
Roy Nelson
> Best regards,
> /Tobbe
> http://www.lotek.nu
> (remove SPAM when e-mailing)
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Message has 1 Reply:
 | | Re: RCX Tank Base
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| (...) Yeah, tell me about it. My latest MOC (still to be published) uses 1 x 6 plates on this type of treads and I made the MOC remote controlled and had to pick up a lot of plates when I was done driving. The treads have some serious flaws but are (...) (22 years ago, 3-Dec-02, to lugnet.robotics, lugnet.technic)
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Message is in Reply To:
| | Re: RCX Tank Base
|
| (...) Why didn't you use a adder/subtracter? (...) If you mount the RCX and motors further back from the hand it will act as conter weight which should allow more lift load. (...) If you remove the 1x4 plates on the treads there will be less carpet (...) (22 years ago, 2-Dec-02, to lugnet.robotics)
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