Mechanisms
The physical design of this head uses some simple linkages driven by servos to move the eyelids, eyeballs, and mouth. Inside the eye is a camera, and in each ear and each nostril there are buttons that act as additional inputs. There is a hidden key inside the skull that gets dropped by a solenoid at a certain point when the mouth is closed as if the head has regurgitated it up.
Electronics
The main control sequencing comes from a Jetson Nano running ROS. Inside the eye is a camera which feeds video to the Jetson. The servos are all connected to a servo driver driven by a MetroMini microcontroller which receives signals over serial from the Jetson. In the back of the head there is a speaker which play sounds in sync with some of the motions. The Jetson Nano lives up in the top of the head where a human's brain would be and there are two fans positioned by the heat sync to ensure the thermals are managed inside this plastic shell.
Software
The control software is all written in python and running in a ROS container. There is a main node that handles the puzzle sequencing and triggers transitions between each phase of the puzzle based on inputs from the other nodes. There is a node to handle button inputs, a node that processes what the camera is seeing using an image recognition model, a node that handles speech and sound outputs, a node that sends servo and solenoid control to the microcontroller, and a node which handles the eye tracking logic.
