**4.1 System description**

The system consists of motors, wheels, and two pairs of spur gears that connect the motors and the wheels. The spur gear was added because the motor shaft was not long enough to support the distance required by the optical encoder. The optical encoder requires some space between the striped disk and the optical sensors to read black and white. The top stage consists of a microcontroller and an H-bridge. The microcontroller is the brain of the robot and is responsible for sampling and processing all the data collected by the sensors. The H-bridge is used with the microcontroller to control the directions of the motors. There is one more sensor attached to a vertical strut between the two stages. In general it is called an Inertial Measurement Unit, (IMU), and this one contains two accelerometers and one gyro to determine the robot's attitude in one angular direction.
