Recently I was presented with the challenge of creating a physical programming project and I was inspired by the children's game Hungry Hungry Hippo. I was able to use the laser cutter in the Fab Lab to create the head of my hippo and the Modkit Micro software to program the Modkit MotoProto Shield and Arduino board that I used to control my project. The Modkit MotoProto board is attached to an Arduino that allows more access for inputs and outputs.
The input of my project was my button, which consisted of two wires (ground and voltage). I created this button using a modela milling machine which fabricated an Eagle program board design for the button. I then soldered the two wires to the button board which allows a headphone jack plug-in to be at the end of my button.
The output of my project was my servo motor, which consisted of three wires (ground,voltage,and sensor). I created the servo motor plug-in by soldering or plugging in the three wires to an attachable headphone jack.
Once my button and servo motor were created I then went to the Modkit Micro software where I was able to define my hardware, and then use my hardware to design the software program that would control both my input and my output. I went to the control tab of the software and took out a forever loop so that my program would continue on forever and never be limited. i then under the forever loop, included an if. The if allows me to program my project so that if a certain action happens to it then a reaction will occur. So with that in mind inside the if I included a button pressed which means that the "if button pressed" is my action, then within the "if button pressed" I set an angle under the output tab. My program now means that if the button is pressed, then it will go to the angle that i set it to, allowing the mouth of the hippo to open. After that angle was set i put in another angle so that my hippo's mouth would be able to close. Then between the two angles I set a delay, so that there would be a certain amount of time that passed before the mouth would close.
Step 1: Materials Used
Servo Motor (https://www.sparkfun.com/products/9065)
2 Headphone Jacks (https://www.sparkfun.com/products/10159)
Wood (3mm plywood - 4 12" squares)
Lasercutter (We have an Epilog at the South End Technology Center @ Tent City)
Arduino (I used a Duemilanove, but it has now been replaced by the Uno: https://www.sparkfun.com/products/11021 )
Modkit MotoProto Board (https://www.sparkfun.com/products/10018; need to solder on headers https://www.sparkfun.com/products/116)
Computer with Modkit Micro Software Link (www.modk.it), Inkscape and Open Office Draw (Open Source Software)
USB connector cord for connecting Arduino and computer
Caliper for measuring
Googly eyes for decorating
Acrylic Paint for decorating
Ball for playing
hot glue gun
Step 2: Design Process
First I drew out the hungry hungry hippo design. I searched on the internet for images of hungry hungy hippo game. I used Open Office Draw to merge shapes that formed the outside of the head of a hippo. I then designed the inner layers of the hippo's head by using only the outline of the hippo's head. I used two layers of wood for the outside of the hippo and 20 inner layers of the outline to form the hollow hippo head. On four of the 20 inner layers, I added knobs for the nose.
I first glued the 20 inner layers together in the correct order with a glue stick and let them dry for about 1/2 hour. I was careful to put the nose layers in the correct place, so that they wouldn't be at the very edge or the very middle.
Step 3: Designing the Place for the Gear to Go
I counted the number of teeth on the gear arm of my servo. Then I used a set of calipers to measure the diameter of the gear.
Then I used these measurements as inputs for designing my gear casing using Inkscape.
INSTRUCTIONS FOR INKSCAPE
Under the EXTENSIONS menu, go to RENDER
Under RENDER menu, go to GEAR. . .
Then in the gear pop-up menu,
enter the number of teeth
enter the diameter of the gear under circular pitch.
make sure the pressure angle is 10.
This should produce a gear that looks exactly like the gear on the servo motor. If not, then increase or decrease your pressure angle on the gear pop-up menu until it does look the same.
Save this gear as an open office draw document (.odg)