This Robot Moves and Steers with Just One Motor

If you want a robot to move forward and steer, you need at least two motors, right? You can have two drive motors and differential steering, or one drive motor and a second motor turning the wheels. But two is definitely the minimum. Except it isn’t, as Pro Know demonstrated by building this robot that moves and steers with just one motor.

Ultimately, this robot works by taking advantage of inertia. But that is difficult and unintuitive to understand, which is why this single-motor approach doesn’t seem possible at first. Thankfully, the video does a great job of explaining how it works visually by increasing the complexity one step at a time.

That starts by showing something you probably expect: put a vibration motor on a table and it will rotate as it vibrates. That happens because the vibration motor has a purposeful imbalance and the resulting inertia causes a wiggle.

But the next part is less obvious and also critical to this robot’s behavior: if you reverse the polarity of the motor, it will spin in the opposite direction. And just like that, you now have a robot that can steer by rotating itself in either direction with a simple polarity change.

To make it move in a straight line, you then rock it back and forth a small amount. If the balance is right, it will shimmy forward a little bit with each cycle. Now it can move forward and steer.

Pro Know showed those principles, then packaged it all up into a self-contained robot. The robot consists of a vibration motor, a battery, an itty bitty ESP01F SoC, and a DRV8212 motor driver. A 3D-printed frame holds all of those components together, balancing them appropriately. An external remote controls the robot via ESP-NOW direct wireless communication.

The result is a robot with just one motor, but which Pro Know can drive and steer around a desktop.