The robot is equipped with two rotating sweeper motors, each equipped with two brushes which spin the dirt into the vacuum radius. One of the challenges of a disc shape design is that the brushes tend to overlap and eventually tangle. In the current design however, the sweeper motor was placed halfway between the wheels, thereby prevents the brushes from overlapping (Fig. 1). A careful consideration of the sweeper system layout shows that the robot actually sweeps an area larger than itself as indicated by the effective cleaning area.