Sunday, 18 December 2011

Hacking the WowWee TriBot

The Tribot is an autonomous robot from WowWee with a nice feature set, including omnidirectionnal wheels, voice synthesis and several sensors. It cost 65 euros, much less on the second hand market (I got mine for 30 euros)

Once I got fed up with its excessively talkative nature (which took less than ten minutes), I started thinking about hacking the beast.

The most interesting part of the robot is its lower part: 3 wheels + 3 reasonnably powerfull motors (with wheel encoders) + the main board (including motor drivers) + the 12V battery case. Building such omni-directionnal robot base with brand new components from a robot hobbyist shop would cost much more than the price of this robot.

What about controlling this robot base with an arduino?

The parts we are interested in in the main board are:
- The 3 H-Bridges
- The Wheel encoder output to get feedback from the wheel rotation
- The 12V output to power the arduino

The wheel encoder outputs are in 12V so they cannot be directly connected to the Arduino (this will be adressed in a future post).

The  H-Bridges input for motor control can be directly connected to the arduino. To do that, I disconnected them from the main chip (using a Dremel on the chip pins) and soldered wires connected to the arduino instead.

Pinout is:
1: Motor 3 direction
2: Motor 2 direction
3: Motor 1 direction
4: Motor 1 enable
5: Motor 2 enable
6: Motor 3 enable
7-9: Wheel encoder feedback (not working properly, more info in a future post)

EDIT: It seems that the wheel encoder feedback does not work properly in this setup (it does not seem to be properly powered). Additional info in a future post.