A giant light flower whose color changes according to the beat when a person sits at the root and touches it "Pulse & Bloom"

ByJim Urquhart / Reuters

A large outdoor festival held every year from the end of August to the beginning of September "Burning man"Money can not be used, all the participants must express themselves in some way. Artists from all over the world gather in the burning man of 2014, when a person sits on the root and touches the sensor, the color changes according to the beat Huge light flower "Pulse & Bloom"Samuel ClayHas released the process until I make a work.

Building Pulse & amp; Bloom - an interactive biofeedback installation at Burning Man 2014 | OfBrooklyn.com
http://www.ofbrooklyn.com/2014/09/6/building-pulse-bloom-biofeedback-burning-man-2014/

This is "Pulse & Bloom" which was exhibited at the burning man which took place from 25th August 2014 to 1st September. From the top, you can see that a person is sitting at the base of the flower.


If we lower the point of view a little like this. In the blue flower some amber shining flowers are mixed.


You can check how "Pulse & Bloom" works from the following movie.

Pulse and Bloom @ Burning Man - YouTube


Looking like this while looking bright.


Clay, who works under a flower with a woman covering her mouth with cloth because the sandstorm is amazing.


Pulse & Bloom was not prepared during the weekly event but was prepared over time from before the event, but in fact it was made through the following five processes.

◆ 1: Custom circuit board
◆ 2: Customize pulse sensor
◆ 3: Use high current LED
◆ 4: Write firmware
◆ 5: Let the lotus flowers shine

So, first of all from custom circuit board.

◆ 1: Custom circuit board
Control of lights and timing and sensors is done on the circuit board.ArduinoYabread boardSo, as there was worry about certainty, ClayOSH ParkWhenOSH Stencilsuse. It seems that we have created seven versions of circuit board before finally finishing.

This board supports a high current LED that makes the flowers light. ATmega series microcomputerATmega 328 PAnd the LED on the axis of the flower was designed with 5V, the pulse sensor 3.3V, the petal LED was designed with 12V. The operation overvoltage regulator purchased for 3 dollars (about 300 yen) was used for the conversion from 12 V to 5 V, and the conversion from 5 V to 3.3 V was carried out by directly soldering the linear voltage regulator to the circuit board.

The layout of the circuit board is as follows. The size of the board is about the package of gum.


Soldering parts such as passive elementsSolder pasteIt took place in.


It is almost impossible to solder by hand because TQFP 0.5 mm pitch is used for the chip. This is also done using the solder paste and hot plate.


This is the substrate.


Wired boards are kept in a plastic case so as not to wear dust or the like.


◆ 2: Customize pulse sensor
Lotus flower shines in conjunction with the human heartbeat, but Clay says that creating a pulse (heartbeat) sensor was the most difficult and it was a fun work.

Although it is certain that expensive sensors work well, this time we used two pulse sensors with $ 6 (about 600 yen) per lotus flower for lotus flowers due to funds problem. A total of 40 sensors were used. The function of the sensor is as simple as reacting when touching with your fingers or holding your hands, but you need to function properly even in places full of sand called the desert.

This is a prototype. When I hold my hand, the light turns on ... ...


When you hold the sensor, it senses the heartbeat with infrared rays, and the light flashes according to the beat.



Eventually Clay decided to use itSi 114 xIt is calledSilicon LabsAmbient light sensor IC. It has three LED drivers, it can implement proximity detection in the range over 50 cm, multidimensional system capable of advanced 2D / 3D motion detection, heart rate / pulse oxygen concentration measurement, etc. It has become.


Soldering is very difficult as Si 114 x is also a very small part, Clay's work efficiency has fallen to 80%. This was also soldering using the hot plate, but in the end it seems that a full cup pulse sensor has become garbage.


This is a completed pulse sensor. A red light will let you know that "Where you should put your finger."


◆ 3: Use high current LED
The best thing that makes the lotus flower like a jewel is the high current LED used for the petal. Nine LEDs, divided into three parts per lotus, were used and moved by a constant current driver.

This lotus was actually exhibited in the burning man. You can see where flowers are blooming even at a distance.


Usually one LED is output by one constant current driver. However, when a person is not in the standby state, the lotus flower remains blue, so Clay used three LEDs with one driver. Lotus flowers shine amber only for a moment of peak current using two channels, 100% red and 50% green.


The LED usually costs 15 dollars (about 1500 yen) from a Chinese vendorSparkFun ElectronicsBuy one high current LED for $ 0.86 (about 90 yen). this isPicoBuck LED DriverAlthough it was a price under the condition that 80 pieces are purchased, it is only a few hundred dollars (tens of thousands of yen) when considering that it was about 1,200 dollars (about 120,000 yen) even if you bought 80 LEDs of 15 dollars, It can be said that it was saved.

This is SparkFun Electronics's high current LED. It is smaller than 25 cent coins.


And this is PicoBuck LED Driver.


The 200 high-current LEDs had 6 anode and cathode, respectively, which required soldering and bonding.


This is how the driver · LED · board is connected.


◆ 4: Write firmware
All source code of Pulse & Bloom is published on GitHub.

Samuelclay / pulse-bloom · GitHub
https://github.com/samuelclay/pulse-bloom


People who want to know about the firmware said it is best to read "pulse.cpp" of "src" on the above page. Advanced logic such as pulse and stationary status is stated.

◆ 5: Let the lotus flowers shine
Burning man creates a town in a vast desert with nothing and exhibits works in it, so the exhibition environment is not set up unlike the galleries in the city. As a result, Pulse & Bloom will also be powered by batteries, but it was my first attempt by Mr. Clay to move the big work with batteries.

First, Clay calculates how big a battery is needed. When in the standby state, the lotus flowers flow 0.75 A · 12 V electricity and when active it changes to 1.5 A · 12 V. As lotus flowers spend 95% of the day waiting, Clay estimated the average current consumption to be 1A.

Because there are 20 lotus flowers of 12V · 1A, 240 Ah is necessary as it keeps shining for about 12 hours in one night. Although it is possible to correspond with the battery for the car, the deep cycle battery that the battery for the car can only discharge up to 80% can be discharged up to 20% if using the deep cycle battery with the ship, etc., this time the deep cycle battery is used It was done.


This is the axis part which becomes the lotus stem. Lotus stem has a width of approximately 1.8 m to approximately 4.8 m and weighs approximately 22.6 kg.


To support the shaft part, so as not to be knocked down by the wind, a heavy weight was attached.


The area around the weight is covered with lily water leaves, where sensors and circuit boards are installed. We confirmed that one of the 20 people in total had light and the remaining 19 were unassembled and Clay moved to Burningman.


A picture of this when heading for Burning Man. I will rent a car and will leave with my bicycle, tent, costume, food etc loaded.


Participants who need to set up works need tickets for early arrival and bands are also attached to the arms.


In a burning man performed in the desert, it is hit by a sandstorm many times every day. Of course, as circuit boards and others are covered with sand,Zip rockWe put it in correspondence. However, as it is not possible to completely block sand smoke, the fact found here is that "circuit boards are extremely resistant to dust." Although it was put in a plastic container so as not to wear dust when making a board, it seems that it actually worked without problems even if it is covered with sand.


When it comes to a sandstorm, it looks like this. You will not be able to see who is near you. Even if it was used roughly in this, sensors and circuit boards were OK.


A burning man performed at a fictitious city "Black Rock City" that appears only once a year is a severe survival event so far as to kill, but to that extent, those who seriously create or express like Clay It is an event where you will have the opportunity to attend. Although it is not officially announced yet, it will be scheduled to run from August 24 (Monday) to Monday 31 (Monday) in 2015, personal tickets for general participants will be on sale around February every year .