These are two brackets that can mount to the bottom of the Trekker to hold photo reflectors. Black and white contrast disks are included that can be read by sensors to allow the microcontroller calculate how far the robot has traveled.
This is a programmable autonomous robot prebuilt kit that can be controlled via USB gamepad. The MarvelMind IPS (Indoor Positioning System) provides indoor navigation. ODROID-XU4 single-board PC provides the most flexible platform possible.