Minerva's eye movement is based on a very creative technique I first was shown by Phil Torrone in his B.O.B. robot seen here, made entirely of recycled cups and containers:
The basic principle is that there are two cups, one inside the other. The outer cup is the head/face and has cutouts for eye sockets -- through which the inner cup can be seen. The inner cup has pupils, irises, and eye whites on it.
When the inner cup is rotated, instant eye movment! Here's a demonstration using two clear cups:
Build the Head
- The head and eyes will be made of two cups, one inside the other. The head will have eye holes cut from it, the inner cup will show through from the inside. Orient them “right side up”
- mark and cut out the two eye sockets as shown. you can use a compass or trace something round for a consistent shape and size — or, just “eyeball” it! (sorry.)
- Trim off any excess height if you want the head to be shorter — just do the same adjustment for the inner eye cup
Make the Eyes
- To make the eyes, first trim the second cup's height down so it'll fit inside the head cup
- Place a strip of white paper around inner cup, and tape it in place
- Draw on pupils and irises or use stickers!
Micro Servo for Eye Movement
- Mark the center point of the bottoms of both cups — this is where the micro servo and servo horn will go to connect through the cups
- You can find center by measuring the diameter of the cup bottom, then halving that number and marking a point at that distance from the edge with a compass
- Poke a small hole through the center of the inner eye cup, and a larger one through the outer head cup so the servo shaft will fit through
- Mark the round collar of the servo on the cup to cut out the shape to hold the servo in place as shown
- Glue the servo in place with a small bit of hot glue
- Do the same to adhere the servo horn to the bottom of the eye cup — you can use a small screw to help with alignment
We'll connect the eye cup's servo horn to the head cup's servo shaft later, but first we'll build the owl's body.
Build the Body
- You’ll use a smaller blue cup inverted for the body. It will hold the micro servo that turns the eyes, as well as hold the full size servo for the wings
- Mark the micro servo’s four bottom screws with marker to make an impression on the “neck” of the body
- Press the servo down with the head aligned in the center
- Cut away the four edges formed by the marker points
- Cut the blue body cup down to size if you like
- Position the full servo on the back of the body so that there will be room for the micro servo "neck" above, as shown
- Cut out the hole for the full servo, then press fit it in place
- Feed in the servo cable first, and then press fit the servo in place as shown
- Cut some material from a sacrificial light blue cup or other paper for the wings and other decoration
- Draw out a wing pattern on one piece, then cut it out
- Transfer the pattern to the underside of another piece of light blue cup material/paper to get the mirror image, then cut it out
- Bend the “shoulders” in a little bit, then hot glue the wings to the body
- We’ll flap the wings with a servo and some yarn. As the servo twists, the yarn that runs from each wing to the servo horn will rotate and cause the wings to flap back and forth
- Widen the holes in two ends of your servo horn so you can thread the yarn through as shown
- Fit the horn onto the servo
- Hot glue one end of the yarn to a wing
- Once the first spot cools, pull the yarn taught and then glue it to the second wing
- Once all glue has cooled, you can trim the excess yarn beyond the attachment points, then tighten the yarn right a bit by twisting it over a servo arm
- Test twisting the servo to see the wing flapping action!
- Add the eye cup to the head now by positioning the servo horn over the shaft
- Gently press until the horn fits in place over the shaft -- you may need to wiggle the eye cup back and forth a bit to find the right spot!
Your robot is built, but now let's add some decoration!
First, we'll add a beak. You can draw on a triangle, or use a sticker, then cut out a proper beak from the light blue cup or paper as shown below.
You can even draw on some eyebrows or use stickers.
Don't forget about Minerva's stylish lightning bolt!
Popsicle Stick Legs
- Carefully trim a couple of pieces from a popsicle stick for legs, then glue them on
- Cut some short lengths of pipe cleaner, and fold and twist them in to adorable little owl feet! Glue them onto the popsicle sticks
Pipe Cleaner Trim
- Bend another pipecleaner to form Minerva's head feathers
- Glue the feathers into place inside the head -- make sure not to glue it to the eye cup!
You can use two more pipe cleaners to create Minerva's distinctive face markings. Shape them and tack them in place with hot glue.
You've completed building your robotic owl! Now it's time to wire things up to the Crickit robotics board!