From GearLive — a robotic drum machine on a tank tread.

What it does? Basically:

Navigate around, collect some data, avoid obstacles, until it
Finds something “worth playing on” (a single isolated object or a wide flat surface that it can find an angle onto)
Snakes into place
Plays some beats on what it have found, and samples this, checking it has a “good sound”
Based on data collected in the area, and sample just made, then compose a little rhythm, and plays this along with the sample

Yellow Drum Machine [Lets Make Robots!]