BIO-INSPIRATION

counter-illumination

Many animals, such as the Japanese firefly squid (shown above) use bio-luminescence to blend in better with its surroundings. Counter-illumination works similarly to counter-shading in which the color of the animals is darker on top and lighter on the bottom. Marine animals, do this so that when they are viewed from the top, they blend into the depths of the ocean, and when they are viewed from the bottom, they blend into the lighter shallow water. Animals with counter-illumination mechanisms operate in a similar capacity, but they use bio-luminescence to blend into the gradient of their surroundings. Using bioluminescence also allows them greater control in adapting to their surroundings.

vertical migration

Vertical migration is a biological mechanism where animals will dive into the depths of the ocean, where it is darker, during the day and resurface at night. In terms of biomass, it is considered the largest synchronous migration in the world. Many animals, such as krill and plankton, exhibit this behavior to avoid predators during the day and to feed at night. These migrations are often triggered by stimuli responses to changes in light intensity. As daylight becomes brighter, these animals will start diving. As daylight becomes darker, these animals will begin to surface.

concepts

concept 1

Concept 1 was a single directional lamp that rotated about a base to constantly point its light at the darkest point in the room. The lamp does this by using photoresistors in the front and back and constantly comparing their values to know if it is pointed at the correct direction. The main issue with this design was the fact that it only provides light to a single point. In order to provide even lighting, the lamp must direct light in multiple directions.

concept 2

Concept 2 is similar to concept1 in that it rotates about abase to constantly point the brightest light at the darkest point. However, the lighting, instead of focused at one point, is omni-directional. In this design, there is always a brighter side and a darker side; the lamp orient itself to the ambient lighting of the room. This solution is inadequate because it is not adaptable enough to variables such as overall light intensity, unevenness of the lighting, and changing sunlight cast shadows.

concept 3

Concept 3 is the concept I decided to refine. It is the most adaptable , but also most complex design. It completely ditches the physical rotation aspect and instead adjusts each of the 8 sides and its respective LED strip according to the needs of the environment that is facing the side. The polygon cross section also allows each side’s brightness to be more discrete and have less interference from the neighboring LED strips.

refinement

refined concept

The final concept is made up of 8 LED light strips each facing a different direction. On top of each LED strip is a photoresistor (8 total) that changes the light intensity based on how dark the are facing the light is. With this design, the darkest areas of the room are always lit with the brightest light. This design also allows for the lamp to accommodate for the natural lighting gradient of the room.

concept drawing

storyboard

prototype

physical model

For my physical prototype, I made a downsized version of my design. The LED strips are attached to the outside of a center spine. The wires connecting the photoresistors to the Arduino are run through the middle of this spine. The outside panels are made up of laser cut acrylic. To diffuse the LED light, I used left over vellum paper on the inside.

arduino circuit diagram

In order to handle the amount of ram required for running 8 LED strips, I had to use an Arduino MEGA board. I also had to wire an external power source as the Arduino MEGA could not handle the amperage required for the LEDs. The Arduino code can be found here. IT takes a light level reading from the photoresistors, and then uses a quadratic function to decide the corresponding RGB LED strip brightness. The brightness levels range from 0 to 1000 while the RGB LED brightness values ranged from 0 to 255. I realized that variations in lower brightness levels were more noticeable than variations in higher levels. For example, 0 to 100 is much more noticeable than 900 to 1000. For this reason, I could not use a linear relationship, and instead had to use a quadratic relationship. This allowed the lower brightness level changes (changes the human eye notices the most) to change the brightness much more than that of the values in the higher ranges. I also had to use different quadratic functions to optimize for different ambient lighting levels. For brighter ambient light, the curve is flatter, while for darker ambient light, the curve is steeper. The code also changes the saturation of the colors along with the brightness, so that the changes are much more obvious.

finished protoype

final model

testing response

testing response

testing response