Figure 2 illustrates its main components. The ellipses represent processes that operate concurrently and exchange information asynchronously. Double border ellipses represent interrupt driven processes that assure real-time response to incoming signals, either sensorial data, control data, or error reports. The rectangles represent shared analogical representations of the world the robot moves in. We consider these representations sub-symbolic in a wide sense.
Arrows indicate the flow of information.
The Perceiver receives information from the ultrasonic sensors arranged around the robot's body. It is a real-time interrupt driven process that is activated whenever the sensors are ready to communicate the sensed data generating an interrupt. The data, in a raw format, are examined and interpreted basing on the system knowledge of the robot's position and orientation. It is then supplied to other processes in the architecture using an information exchange protocol. It is important to mention that, to obtain a robust robot behaviour, the navigation algorithm is not directly based on sensor data but on a dynamic world representation built fusing these values with previous readings and a priori knowledge.