After an object is placed on the touch screen, Liatris knows both the undefined object’s pose (relative to LP) and its orientation. To determine the object’s identity, it reads an UHF RFID tag placed on the object. The tag must be placed at a specific point on the outer surface of the object. This position is determined by starting at the LP and following the object’s orientation to the outer wall.

RFID tag's location relative to LP

In the example code, the right arm of the robot holds a RFID antenna. After an object’s pose is calculated by the local network, the RFID reader is placed 20 cm in front of the LP. The robot also rotates the antenna to be perpendicular to the orientation of the object.

The RFID’s antenna reads the RFID tag and POSTs its value to the local network.

RFID’s antenna reads the RFID tag

A Ruby script, rfid_to_server.rb, handles this.

Note: This script uses Alien Technology’s Ruby API, but the logic could be applied to any RFID reader’s API.