I'm developing the Falling-Up Robot, a very tall balancing inverted pendulum bot, using the Teensy 3.6 microcontroller with Arduino IDE 1.6.12. I want to practice feedback control systems with this robot. I want to keep it from falling over while roaming autonomously and interacting with its environment. I'm building this in stages. So far, the brain and chassis is in place, and the basic balancing control system is in place. Here's the first video.
I used stepper motors to take advantage of high torque at low RPM and zero backlash (or zero freeplay). Dealing with the high mechanical vibration was an issue, but was solved with analog filters in the IMU and an Extended Kalman Filter in software.
More details here: