P-hex

p-hex is a hexapod robot, built most from bits of a bioloid kit, scrap metal and assorted pieces of tech, designed to be controlled from an openpandora handheld.


Hardware

The hardware for p-hex consists of 2 scrap plates salvaged from old monitors, and 6 legs, constructed from the parts of a bioloid kit, each with 3 servos.
The servos are all connected to a USB->dynamixel bus adapter, which is in turn connected to a usb hub. The USB hub is required for 2 reasons:

  1. The usb port on the openpandora is USB 2.0 only, so needs to be converted to USB 1.1 through the hub to make the adapter work
  2. In case further USB devices require more power than the pandora can provide

Also attached to the USB hub is a wireless xbox 360 adapter, which is used for direct control of the robot.

P-hex is powered by an RC car type battery, with a voltage range of about 7-12v for the servos (the pandora has a separate battery).


Software

The software on the other hand never made it past the early stages, hitting several stumbling blocks in the inverse kinematics code. Regardless it was interesting to find some of the problems met when mixing hardware and software. Fortunately the dynamixel servos are fairly clever and will shutdown if the legs collide/servos reach an overload state. The little code that was written in however relatively functional and a few initial demos of the kinematics code did give promising results: GitHub Repository