05. mini-project [ James Liu ]

Drowning Man Automaton

Using a rangefinder, two dc motor fans, one servo, and an external 12V wall wort, this project simulates a drowning automaton. The automaton is driven by a single servo motor and waves his arms for help. When someone get’s close.. the dc fans kick up the ribbons and confetti, and the automaton “drowns”. Even though it’s not completely working.. I think the idea is still conveyed.

Arduino Sketch: DrowningMan

Materials

Electronics
2 DC Fan Motors: 12V 1.2A
1 Large Servo
1 Range Finder
1 Arduino Duemilanove ATmega328
1 DC 12V wallwort
1 TIP120
1 200Ohm resistor
1 diode
1 breadboard

Physical Materials
Wooden Scraps
Black Picture Box
Tissue paper for confetti
Ribbons for Water
Metal Mesh
Black Tape
Metal nuts & bolts

Process

Constructing the Automaton

The automaton was the hardest the construct. I started with initial sketches to work out the mechanisms. Through mostly trial and error as well as well internet references, I used wooden pieces to create an oscillating motion for the “waving of the arms.” I secured the wooden pieces together using small metal bolts.

Next the entire setup was attached to a servo base—driving the waving of arms by sweeping from 0 to 180 and backwards. I painted the wooden backing black using acrylic paint—I wanted to give the automaton a more “humanoid” like form.

Making the Box

I attached two DC fans near the base of the box—making sure to give enough space and openings for the air intake. I used a small sized wire mesh to cover the intake and exhaust for the fans. A flush wooden bar was placed in the middle of the box (attached with a wire mesh) to separate the wooden box into two chambers.

The first chamber held the automaton, tissue paper confetti, and ribbon that simulated water. The second chamber held and range finder. Finally the box cover was cut and covered with a transparent acrylic and a metal mesh for the lower chamber.

Electronics

The electronics was very straight forward. The Servo only required the onboard 5V power source and an analog pin-out—I simply plugged this in directly. The two DC motors required more work. By using a TIP120 and an external power supply, I was able to use the Arduino to control the speed of the fan. Finally, the range finder was also very similar to the Servo—only requiring a 5V power source and an analog pin-in.

Lessons Learned

The fan was not powerful enough to achieve the effects I wanted. However, I still consider this project to be a success. I would only need to use more powerful fans in order for this project to work. The mechanics was perhaps the hardest part of the project; I spent most of my time on the craft of the project as opposed to the electronics. Not only did I need to make sure the mechanical components was sufficiently robust—I also wanted to make it look good. This is a picture of my work area 🙂

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~ by jamescmliu on March 19, 2010.

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