Olin university chapter/Projects/XOBot: Difference between revisions

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==== Hardware Selection ====
==== Hardware Selection ====
* XO
* We're looking to use Vex Servo Motors for drive
** (+) Low cost, about $20 a pop
** (+) Already available in the classroom
** (+) Easy to aquire
** (-) heavy, requires more torque
* Casing - Sheet Metal
** (+) Accept PWM and have velocity control, but unlike normal servos are continuous
** (+) cheap material
* Delrin parts for structure
** (+) easily/forgivably manufactured without much machinery
** (+) Delrin is light weight and parts can be assembled without tools
** (+) designs can easily be distributed and reproduced via the internet or mailing full-size schematics
** (+) Many companies will cut and send you Delrin parts at low cost (http://www.ponoko.com/)
** (-) needs some work on safety - the metal is not sharp enough to cut but is sharp enough to scratch. It would be nice to eventually make this a plastic part
* TODO: Determine rest of parts and cost estimate
** (-) conductive - we placed a non-conductive coating (duct tape) on the bottom so as not to ruin the electronics. Another solution would be to have a plastic electronics box
* Batteries - XO batteries
** (+) available where there are XO's
** (+) can be recharged by placing them in the XO
** (+) enough power to move the bot
** (-) requires disassembling a computer, or coming up with a better solution for connecting power terminals - we used part of the bottom plate of the XO to ensure a good connection
* Microcontroller: Arduino Diecimila
** (+) easy to use
** (-) a bit expensive - might move towards a plain ATMega168 or 328 in a low-cost version, although that makes do-it-yourself XOBot's a little more challenging
* Motor Shield: Ardumoto(uses L298)
** (+) just works - basically this was a time-saver
** (-) expensive - We'll definitely make our own motor shield from plain L298's in the next version
* 2 Motors: Beetle B104
** These motors worked fine, but were expensive because the robot was heavy. We're moving towards eliminating the XO from robot and either pre-program the robot or use a wireless connection to send commands.
** We also considered modified RC Servos, but were concerned they wouldn't have enough torque to move the robot.
* Wheels - Lite Flite foam wheels
** (+) again these worked very well with only a few small issues
** (-) required some hacking to connect to our hubs
** (-) picked up dirt from the ground
* Hubs
* Rear axel
** We don't have one yet. Probably will just get some metal rod
* Miscellaneous screws, USB cord, plastic connectors


==== CAD of the XO ====
==== CAD of the XO ====

Revision as of 21:58, 31 December 2009

XOBot

Project of Olin College. Ideas is to create a simple, low cost XO Robot and interface the hardware components with Scratch or some XO friendly graphical programming environment.

Project Components

Hardware Selection

  • XO
    • (+) Already available in the classroom
    • (-) heavy, requires more torque
  • Casing - Sheet Metal
    • (+) cheap material
    • (+) easily/forgivably manufactured without much machinery
    • (+) designs can easily be distributed and reproduced via the internet or mailing full-size schematics
    • (-) needs some work on safety - the metal is not sharp enough to cut but is sharp enough to scratch. It would be nice to eventually make this a plastic part
    • (-) conductive - we placed a non-conductive coating (duct tape) on the bottom so as not to ruin the electronics. Another solution would be to have a plastic electronics box
  • Batteries - XO batteries
    • (+) available where there are XO's
    • (+) can be recharged by placing them in the XO
    • (+) enough power to move the bot
    • (-) requires disassembling a computer, or coming up with a better solution for connecting power terminals - we used part of the bottom plate of the XO to ensure a good connection
  • Microcontroller: Arduino Diecimila
    • (+) easy to use
    • (-) a bit expensive - might move towards a plain ATMega168 or 328 in a low-cost version, although that makes do-it-yourself XOBot's a little more challenging
  • Motor Shield: Ardumoto(uses L298)
    • (+) just works - basically this was a time-saver
    • (-) expensive - We'll definitely make our own motor shield from plain L298's in the next version
  • 2 Motors: Beetle B104
    • These motors worked fine, but were expensive because the robot was heavy. We're moving towards eliminating the XO from robot and either pre-program the robot or use a wireless connection to send commands.
    • We also considered modified RC Servos, but were concerned they wouldn't have enough torque to move the robot.
  • Wheels - Lite Flite foam wheels
    • (+) again these worked very well with only a few small issues
    • (-) required some hacking to connect to our hubs
    • (-) picked up dirt from the ground
  • Hubs
  • Rear axel
    • We don't have one yet. Probably will just get some metal rod
  • Miscellaneous screws, USB cord, plastic connectors

CAD of the XO

Hard(er) to CAD interfacing parts (the Bot kit itself) without a CAD of the XO.

Check out XOCad !!!

Zwiebel top mostly closed render.png

CAD of the Bot Kit

  • TODO: Design and produce CAD
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