Hardware Hacking  The Roomba
To Build You Own Robot

The iRobot Roomba is a great robotic device for hardware hackers and robot builders. 
They can be found on Ebay for as little as $20 with and without batteries. The battery pack seems to be the main reason they get sold because most users just don't want to bother replacing the battery, which costs about $45 on Ebay. Other items that cause problems are dirty wheel sensors, a siezed cleaning brush motor and an occasional broken drive belt. Most of these problems aren't a concern to hardware hackers.

The Roomba contains a variety of sensors, motors and raw hardware that can be disassembled and used to build other roving robot devices. 

I found the motors in the Roomba to be very user friendly. The have a belt driven planetary gear reduction transmission that provides very high torque and they can be driven directly from the H-bridge that is already on the Roomba main board. Each assembly has a wheel sensor but it tends to drift in it's accuracy due to the belt drive slipping slightly.

I recently built a four wheeled rover robot with a rocker bogie suspension, a PING sensor and an Arduino micro controller. I mounted four of the Roomba motor assemblies on the suspension arms, two on each side. They were then connected to the mainboard at the factory plug. In doing this I burdened the circuit with double the normal load because I was using two motors per side. The power transistors seem to handle this just fine however and I noticed no heat buildup in them.

The Arduino microcontroller I installed is programmed to send a PWM signal to the switch on the transistor on the H-bridge of the main board, which is powered by the Roomba battery pack. The PING sensor is mounted to the front of the chassis for navigation. Here's the proto type in action.

Urban RoverBot Field Testing

I’m currently working on a final design to take to the 2010 Maker Faire in San Mateo in May. I’ll be building a new chassis and suspension assembly out of aluminum and making use of one of the IR edge sensors from the Roomba. I’m working on a really neat wheel drven by the stock motors… stay tuned.