Inexpensive crab module?
 

I'm looking to design a crab drive robot over the summer... on my own budget. That budget? A McDonald's check... *sigh* So... here's my question. Can somebody design a relatively cheap and innexpensive crab drive module? Or atleast give me ideas on what to use. The entire robot will be 28X28. I'll be using 4" diameter wheels. I don't know what kind of wheels to use. If anyone can provide me a link to innexpensive wheels that'd be great. Also be using drill motors geared down for the drive... b/c I can get them very cheap. So... if anyone needs any more information then ask. I know I probably didn't provide enough info but it's the best I can do on what I know.

PS - I would ask some of the engineers on my team to help but they are mostly on vacation for a few months from robotics.

Re: Innexpensive crab module?
 

You say that you will be using drill motors. Will you also be using the drill transmissions?

If you are you may be able to direct drive the 4" wheels to the drill output and save the cost of chain/belt/pulley/gears.

A chunt of plastic such as Delrin or Nylon can may a good inexpensive pivot/thrust bearing for your crab module and it is much cheaper than roller bearings.

Matt B.

Re: Innexpensive crab module?
 

i think wildstang's crab drive from 2003 is a good bast to copy from it had 4 delrin bushings around a bottom plate that had some pillow blocks the wheel and a transmition and the weight was supported from the top by what i believed to be something like a lazy Susan bearing, not good for side load but it didn't matter with the delrin at the base. i wish i could find the pictures of it but it looks like nobody has tagged them in CD media yet im shure Raul Could elaborate further.

Re: Innexpensive crab module?
 

You can find many pictures in our gallery. Here are some albums that have some shots of the modules and mounting points. If you want more information, I would suggest contacting Raul. He'll be able to give you more details than I could.

http://www.wildstang.org/gallery2/v/..._Construction/
http://www.wildstang.org/gallery2/v/...3_Robot_Proto/

(Note that in the side-by-side album, you can see our mythical stacker that was removed early on at Great Lakes)

Re: Innexpensive crab module?
 

So... to use Nylon... I would put the Nylon between the frame and the module to reduce friction? And then a bearing on the shaft between the shaft and frame. I think I understand what you're trying to say. Anyone know where I could get some of this stuff?

Re: Innexpensive crab module?
 

mcmastercarr.com in the plastics section.

Re: Innexpensive crab module?
 

Does anyone know where to get a microcontroller and operator interface/radio for cheap? Needs analog outputs and C programability. I found one... but I just wanna shop around before commiting.

Re: Innexpensive crab module?
 

RobotCombat is a great place to look for anything related to robotics.

Re: Innexpensive crab module?
 

Thanks... I've been to this site multiple times.

Question: If I buy an R/C transmitter and receiver... How do I incorporate that with the controller? And also... how would I go about making my own transmitter? With joysticks and all... I know how to do it with the FRC operator interface but what about with a different one?

Re: Innexpensive crab module?
 

I don't know, you should probably try Greg Needel, he might know.

Re: Innexpensive crab module?
 

I PMed Greg.

I also found a transmitter/reciever package from RobotMarketplace but would prefer to make one identical to ours from this year and the past couple of years.

I'm using the MTJPRO11a microcontroller from MrRobot.com.

Re: Innexpensive crab module?
 

The best deal on a combination radio controller and C programmable microcontroller right now is the VEX kits selling for $150 at radioshack.

Re: Innexpensive crab module?
 

Will the VEX kit radio and microcontroller work for a bigger robot? I have a VEX kit ordered... but for a VEX robot.

Re: Inexpensive crab module?
 

You can use the Vex transmitter/receiver/microcontroller to drive Victor speed-controllers, which can then be used in a manner similar to FRC to drive motors on a big robot.

-JV

Re: Inexpensive crab module?
 

Hm... how many Victors can I run with one VEX microcontroller?