Building a Self-Balancing Robot – The Base

In my first post about a self-balancing two-wheeled robot I introduced the prototype. Now it is time for the beginnings of the construction of the ‘real’ thing. This post focuses on the platform. In order for it to be sturdy enough to eventually let a human ride on it, I opted for a pair of wheelchair motors with wheels that I bought used from ebay. The pictures show the dimensions (inches) of one of the Pride Jet motors with the attached gear box.

2009-12-30-18-18-12-028-cropped-small   2009-12-30-18-19-42-030-cropped-small

The motors come with an electric brake attached at the end opposite to the gearbox. In the photos the black bowl shaped cover and the electric brake (still attached to two white wires) have been removed from the motor. Instead of the brake I will attach wheel encoders (more about this in a later post). The matching wheels came with the motor.


In a wheelchair the motors are mounted horizontally. However, in order to gain more ground clearance I decided on a vertical mount for the robot. The next pictures show the assembled wooden base of the robot.

2010-01-05-16-36-00-002-cropped-small 2010-01-05-16-37-54-004-small

The gearboxes are attached to a board on the underside of the round base board. On the top of the base board, behind the motors that stick out from below, two sealed lead acid AGM (Absorbed Glass Matt) batteries are mounted. The off center configuration balances out most of the motors’ weight. The two batteries, model RBC6 12V 12Ah SLA Sealed Lead Acid AGM, are offered by Battery Geek on ebay for US $31 plus US $12 shipping.

This covers the construction of the base. Apart from the motors and the batteries all materials can be bought in a local hardware store.

Next I will work on the electrical system and the electronics. Stay tuned …

Leave a Reply

Your email address will not be published. Required fields are marked *