Roomba

OBSTACLE AVOIDANCE

 

• CLIFFS AVOIDANCE

The Roomba is well equipped to avoid cliffs. Cliffs refer to a steep drop in the height of a surface in a typical house. For example, a flight of stairs, or a step that leads to the kitchen, or the entrance to the house. Theses cliffs pose a hazard to the Roomba in two ways.

 

Firstly, because a Roomba was built for flat surfaces and is unable to effectively ‘climb’ stairs; going down a cliff would render it unable to climb back up. This prevents it from returning to its self-charger once its batteries are flat.

Secondly, should it not avoid a flight of stairs, Roomba would unceremoniously tumble down the stairs, damaging its equipment in the process.

 

Roomba uses four infrared sensors on the front underside of the unit called Cliff Sensors. These sensors constantly shoot out and receive infrared signals. The signals bounce back within a certain time when the Roomba is travelling on a flat surface. When it approaches a cliff, this bounce-back time increases significantly, telling the Roomba that it is approaching a cliff. This is how Roomba knows that it has to turn and head another way.

 

• WALLS AVOIDANCE

Besides being able to avoid bumping into walls, the Roomba knows how to position itself to clean in a straight line, along a wall. How it does this is with the use of a wall sensor located on the right side of the unit.

 

The wall sensor contains an infrared receiver and an emitter. The emitter contains a diode which transmits infrared light. This invisible light bounces off a wall and is received by the receiver. The receiver is positioned in a way that the infrared beams always hit the wall at a specific angle.When the robot is at an ideal distance from the wall (0.2 inches), the infrared beams bounce directly back to the receiver.

 

If the receiver does not receive these beams, the Roomba is either too close or too far from the wall. A circuitry board inside the robot analyzes this information and adjusts the path accordingly. In an ideal state, the Roomba travels 0.2 inches from a wall and moves in a straight path allowing it to clean sidewalls effectively.

 

• VIRTUAL WALLS

Virtual walls create an invisible barrier that Roomba will not cross. This technology also uses infrared signals but the emitter and receiver are separate from each other. The emitter is a separate unit that comes in a box when you buy a Roomba robot.

 

When placed on a wall, it emits an infrared beam up to seven feet long. The receiver is located on the top of a Roomba unit. When a Roomba approaches and detects this virtual wall, internal circuitry reroutes it onto another path and avoiding the barrier. Virtual walls allow Roomba to be confined to a particular room or area, and prevent it from getting too close to electrical or computer cords, delicate objects on the floor, etc.