SLAM/GPS 4WD Offroad robotic experimental platform

This is a large (2.5kg with hardware, ~504030 cm) all wheel drive 'platform' for GPS/SLAM experimentation.

There is some footage of it using GPS to navigate here:

http://youtu.be/Q1CUnUzaENc

and using LIDAR to avoid obstacles (but not phone cameras) here:

http://youtu.be/v2fPF3EMCtM

The EOP is designed to:

• be printed on a printer with build volume 140mm width, 140mm depth, 135mm height i.e. Up Plus, makerbot or most hobby printers should suffice, but you know the limits of your own printer!!!
• to be very flexible. there is a basic chassis. Parts click on and off (mostly - some need bolts and nuts) and you can add or modify the accessories (LCD, breakout boards, gopro/virb mount etc) and suspension.
• uses skid steer (see motor/battery/relay combination I use below to make this work at this weight). It works very well - will climb until it flips over.

I have included the CAD file (rhino .3dm) to aid modification (UPDATED 13OCT2014).