The animatronics are controlled by a comedian thanks to some face-tracking software I wrote. The code uses Google's TensorFlow and their FaceMesh model to easily measure how wide open the comedian's mouth is, and how raised their eyebrows are. Then, I transmit those numbers wirelessly to the backpack using an arduino with a nrf24l01+pa+lna module at both endpoints.
I spent a TON of time trying to make the animatronics really silent, so that you don't hear the noises of the motors and the mechanics. It turned out to be a suitable challenge for people that like challenges. Initially I used servo motors, but even after greasing up the gearboxes and swapping the electronic guts with some ultrasonic drivers from pololu, they were still too loud. Then I switched to stepper motors that were really oversized for the job, and with microstepping the motor noise went away (or rather, was now low enough that you didn't really hear it over the comedian's voice coming out of the speaker). At that point though the mechanics were still making noise, so I put vibration dampeners (rubber cylinders with threaded rods sticking out of both ends) on all the pushrods and also to isolate the stepper motor from the metal mounting brackets, and then I had a nice quiet system. Hopefully someone in the future reads this and it saves you from making the same mistakes.