Final Project, IV: Making the Head

       While I was working on the jaw all this time, Marie and Christine had already produced a code for their parts. They had used 3 ultrasound sensors for detecting movement. The code determined which one or two were covered and this gave the direction in which a person was moving. The eyes would follow this direction, while the eyebrows and eyelids would change to the "alert state" by opening and rising when motion was detected. This was great but they needed to test this on the actual parts because they needed physical constants for their code based on the material we used. I did some googling to find out what the average person's eyeballs and eyelids' size were. We ordered 1 inch polypropylene balls for the eyeballs and standard ping-pong balls for the eyelids. They arrived a few days after Marathon Monday and were added to the Lego mechanism on that Friday. Christine and Marie did this by drilling a hole in two of the plastic balls that fit a rod. They also cut one ping-pong ball into to to get to eye lids. At this point, we had a preliminary structure to put the mechanism behind. Here is what the face looked like:

The face and eyes, being held by Christine in this picture

         To build the face and the back of the head, I first measured our

heads. I looked up the relative positions of facial features of an average person. Next, I drew an ellipse on SolidWorks that was the average of our faces big. I put two holes for the eyebrows and two holes for the eyes. I cut the part from the imaginary nose below for the jaw. We thought we would wire fit the face with the box structure around it, so no other holes were made. I also built a box structure, which we can call the skull, to rest our mechanism in. It was 15 cm high, 13.5 cm wide and 12 cm deep. We decided on these dimensions after looking at the Lego structures and how much space they took. This box structure was to be connected to the face at 4 cm. We printed these parts on 3/16 inch thick Delrin sheet. With EJ's help, I drilled holes on these parts so that we could put the wire in. However, when the time to cut the piano wire came, me and Lyn had serious  difficulties. There was no way to cut so many pieces of wire and be able to  locate all the pieces flying across the room in a reasonable amount of time. I hadn't wanted to use press fitting because I had found it hard to calculate and not very reliable during our bird project. However, I had no option so I got to work. Briana had been doing a lot of press fitting for the Creep and she kindly helped me understand the principle behind tight fit. I used her notes to calculate the holes and draw a new head structure for Wendy. I first printed two rectangles: one with a hole and one with a piece sticking out to try my tight fit. It was very tight and I was happy with it. I printed the rest of the parts using the following files:



Two of this part made the sides of the skull

This is the back of the skull.

The face

        The fıt was so tight that I needed to use a hammer to put all the pieces together. This was great beause it also meant that it'd be hard for them to come off. Marie and Christine taped their Lego motors and put the mechanism inside. They started debugging their code. I started to get the jaw ready to put into the skull. Due to an error in my calculations, it was about 5 mm too wide to get into the skull. While they were trying to make the eyes follow reliably, I was filing away my precious jaw...