Ever wonder how car dashboards know to display the distance the car has travelled? Well, the secret is in the wheel rotations! Every car's wheels' circumference is a known measurement, so the number of degrees the wheels have rotated can be used to calculate the distance the car has travelled.

The same kind of wheel rotation sensor is used in the CoderZ Simulation, and it is called the **Encoder**. Every motor has its own* *encoder. That means one for each of the robot's wheels, and one for the arm. It measures the motor rotations in degrees.

Here's what it looks when the robot drives forward for one full wheel rotation. The Encoder data is visible in the HUD:

**Using Encoders to Measure Distance**

The EV3 robot wheels' circumference in the CoderZ Simulation is **8.8 centimeters**, which means that one full 360-degree rotation of the robot's wheels will drive the robot 8.8 cm. Using encoder measurements to drive exact distances is more precise than any other sensor input!

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