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6 Common Sensing Techniques for Reactive Robots
Step 1: Describe the task. The “Hors d’Oeuvres, Anyone?” event required
fully autonomous robots to circulate in the reception area at the AAAI confer-
ence with a tray of finger food, find and approach people, interact with them,
and refill the serving tray. Each robot was scored on covering the area, notic-
ing when the tray needed refilling, interacting with people naturally, having
a distinct personality, and recognizing VIPs. The USF entry used two robots,
shown in Fig. 6.30, costumed by the USF Art Department in order to attract
attention. The Borg Shark was the server robot, and navigated through au-
dience following a pre-planned route. It would stop and serve at regular
intervals or whenever a treat was removed from the tray. It used a DEC-talk
synthesizer to broadcast audio files inviting audience members to remove a
treat from its mouth, but it had no way of hearing and understanding nat-
ural language human commands. In order to interact more naturally with
people, the Borg Shark attempted to maintain eye contact with people. If it
saw a person, it estimated the location in image coordinates of where a VIP’s
colored badge might be, given the location of the face.
When the Borg Shark was almost out of food, she would call over radio
ethernet her assistant robot, Puffer Fish. Puffer Fish would be stationary in
sleep mode, inhaling and exhaling through her inflatable skirt and turning
her cameras as if avoiding people crowding her. When Puffer Fish awoke,
she would head with a full tray of food (placed on her stand by a human)
to the coordinates given to her by Borg Shark. She would also look for
Borg Shark’s distinctive blue costume, using both dead reckoning and vi-
sual search to move to goal. Once within 2 meters of Borg Shark, Puffer Fish
would stop. A human would physically swap trays, then kick the bumpers
to signal that the transfer was over. Borg Shark would resume its serving
cycle, while Puffer Fish would return to its home refill station.
Both robots were expected to avoid all obstacles: tables, chairs, people.
Since there was a tendency for people to surround the robotos, preventing
coverage of the area or refilling, the robots had different responses. Borg
Shark, who was programmed to be smarmy, would announce that it was
coming through and begin moving. Puffer Fish, with a grumpy, sullen per-
sonality, would vocally complain, then loudly inflate her skirt and make a
rapid jerk forward, usually causing spectators to back up and give her room.

Step 2: Describe the robots. The robots used for the entry were Nomad 200
bases, each with a unique sensor suite.