This Wheel-Balanced Inverted Pendulum Is a Great Demonstration of Inertia

For people who haven’t experienced it for themselves, it’s difficult to understand how a bicycle or motorcycle remains stable at high speeds. After all, they’d just fall over when standing still if it weren’t for the kickstand. But, the truth is that they become more stable at high speeds, and that’s thanks to the gyroscopic effect caused by the inertia of the spinning wheels. Inertia can also be harnessed for another form of stability, like with this self-balancing inverted pendulum.

Gonzalo Belascuen and Nahuel Aguilar from the Instituto Tecnológico de Buenos Aires created the device to be presented at the IEEE ARGENCON 2018 in Argentina. It’s an inverted pendulum, so the pivot point is at the base and the arm stands upright. When it’s not running, simple gravity takes over and it falls over. But, when it’s turned on, a motor spins a disk to generate inertia that counteracts gravity as the pendulum tips, and it remains upright. It’s even stable enough to withstand strong lateral pushes.

This works with a feedback loop similar to what you’d find on a Segway or Hoverboard, except there is no ground traction to push on. Instead, the disk’s spin is precisely controlled with a microcontroller (what appears to be an Arduino Uno). From a resting position with no kinetic energy, the wheel begins spinning at high speed towards the center position. When the wheel is suddenly stopped, inertia takes over and the arm swings towards center. More subtle spin-and-brake movements are then used to keep it stable in the upright position, allowing it resist lateral pushes.