The reflectance sensors are easily the most important part of the AEV design project. The reflectance sensors are continuously tracking the position of the AEV at all times. They count marks to ensure the actual position of the cart relative to where it started. This is the most important piece of the MCR because of its ability to know where the vehicle is at all times. This part controls whether or not the vehicle should continue to give power to the propellors or not. This is crucial because of the segment in the track in which the vehicle must stop.