This self-balancing robot was designed and built by Kerry Wong and uses just a few ICs and some basic electronic components to get the job done. This project is definitely more up your alley if you’re interested in using discrete components rather than a microcontroller designed for prototyping, but the cost in doing it this way makes it attractive.

From Kerry’s site:

I used a LPY450AL for the gyroscope and anMMA8453Q for the accelerometer. These two devices are rather inexpensive and the IMU can be built for well under $10.

The toy truck I used for this project has a single motor that drives both of the rear wheels. Since I only need the drive wheels, I cut off the unused front portion. The toy car’s plastic chassis is not rigid enough so I hot-glued a few pieces of plastic and metal support on the back. The extra support is important as excessive vibrations affect the accuracy of the sensor measurements.

Here is the bill of material in my build:

Platform: Toy truck (0 – $20)
Controller: ATmega328P (~$4)
Accelerometer: MMA8453Q (~$2)
Gyroscope: LPY450AL ($4)
H-Bridge: SN754410 (~$2)
Miscellaneous: ~$10

[via Hacked Gadgets]