TESIS DOCTORAL - Robotics Lab - Universidad Carlos III de Madrid

152 Chapter 7. Implementing the decision making systemLoad data aboutRFID objectsRFIDOBJECTSXML FILE[non RFID tag detected][RFID tag detected]Read data fromRFID tagShortTermMemory[new object Oj][it was recentlybeing detected]event(DISCOVERED_RFID_OBJECT,Oj_id)CheckingdisappearingtimeoutsReset disappearingtimeoutUpdate the list ofrecently detectedrfid objects[all timeouts > 0][timeout for object Oi is 0]event(DISAPPEARED_RFID_OBJECT,Oi_id}Update the list ofrecently detectedrfid objectsFigure 7.11: Activity diagram of RFID discoverer skillThe skill implementing this action is called the Charge skill. The process for rechargingthe battery is shown in Figure 7.13. The first step is to determine if the robot is alreadyplugged. If it is not, it approaches the docking station using the navigation system. Therobot knows several well-known positions and the location monitor skill (Section 7.4.1)is in charge of moving it to the front of the docking station. Once the robot is facing thedocking station, it has to accurately center its plug to the socket in the charger. This task isachieved by means of the laser telemeter which gives higher resolution than the geometricnavigation. Then, Maggie moves back until the plug fits into the socket. This is detected bythe Docking Station Sensor skill (Section 7.4.3). In the last step the robot remains pluggeduntil its battery is totally recharged. Finally, the successful end of the action is pointed outby emitting the CHARGED event. In case an error occurs, an event, which indicates the typeof error, is sent.