mBot Robot Bumper

The [mBot robot](http://www.makeblock.com/robot-kit-series-STEM/mbot-v1-1-stem-educational-robot-kit) is a very nice kit to teach robotics to kids. While developing some maze solving code, the mBot would sometimes get stuck (see photo). This bumper prevents (most of the time) the mBot from getting stuck. Here's a [video](https://youtu.be/xsSRP68nFK4) of the mBot solving a maze.