In the 2001 film A.I. Artificial Intelligence, one of the characters is actually a teddy bear, named… “Teddy.” Interestingly, instead of being created using CG, Teddy’s character comes to life for the most part via a very impressive puppeteering rig. Inspired by this character, YouTuber James Bruton decided to also bring Elmo to life, this time with a robo-rig that does roughly the same thing.
Bruton’s build starts out in the first video below with him constructing the leg assembly. This consists of two motors to push it around in a differential control setup that will be familiar to many readers, and a servo/slider/linkage system to move the legs somewhat convincingly along the ground. The upper body is addressed in the second video, and moves the torso and head independently via a servo/linkage system for each. Additionally, a pair of servos are used to raise the arms independently and a final servo actuates the mouth.
Control for the animatronic Elmo comes in the form of an Arduino Mega board, plus an nRF24L01 radio module to link it up with Bruton’s Open Dog RC transmitter. The newly “alive” Elmo can be seen traipsing around outside just after 7:00 in the second clip.
Results are quite impressive, though without explanation, one might wonder about the black supporting structure following him around. For that matter, one would have to ask why Elmo is wandering around by himself in the first place!