Making Things Interactive

February 28, 2008

7: Mid Term Project Proposal

Filed under: 7: Mid-Term Project — jmarshman @ 4:59 pm
For my mid term proposal I chose to develop a simplified component of what will likely be my final term project. The ‘light cloud’ is a responsive hanging light installation that reacts to movement of people in a public space below. The cloud is composed of a high density of LED’s which scatter or converge depending of interruptions in depth perceived by a grid of range finders. The movement of each single LED in 3 dimensions forms various clusters/voids of light, ultimately questioning one’s perception and understanding of the cloud itself as various forms and spacial conditions are suggested, similar to a cloud of rain.
The complex movement of each single LED in 3 dimensions is achieved through complex fabrication, though realitively simple circuitry and code.
First, a 1′ x 1′ grid is created of elastic white string, joined at each intersection point along the grid. Single moveable LED’s (white) are “hung” on each corresponding section of string between two grid points (40 LED’s total). Each LED is attached to a small hook or slider which allows it free movement along its individual section of stretchy string.
Next, the 4 corners of the grid along with 4 primary interior grid points are attached to 8 individual rigid wires which are attached above to 8 individual servo motors. Each wire moves up or down along the y-axis according to each individual servo, and when this occurs the elastic string grid is pulled up or down at corresponding points, creating a multitude of possible grid deformations.
The point is that when the string grid is deformed in 3D, each individual sliding LED will slide away from or towards the deformation, creating various clusters and scatterings. If the servo pulls the wire up, the corresponding point in the grid is pulled up and LED’s slide away from this point. If the servo lets the rigid wire down, the corresponding point in the grid moves down and LED’s converge upon this point.
The multitude of potential light configurations within this system are determined ultimately by the movement of people or objects below. 9 range finders fixed below each servo motor detect interruptions in depth at a given distance below.
Parts List:
12″ x 12″ White Acrylic Sheet (1/4″ or 1/8″)
40 Bright LED’s (White)
Elastic String
Rigid Wire
Hooking mechanism from LED to string, probably some sort of manipulated mechanical fastener
9 Range Finders
8 Servo’s
Mechanical bracing/screws to connect range finders and servo’s to acrylic
“Code Sketch”:
Input: 9 range finders, max dist. ~8ft.
Output: 8 servo motors, states A, B, or C (wire down, eq., or up), int servo at state B
Output: 40 LED’s, state ON (always)

If range finder ‘A’ depth is <8ft, servo ‘A’ retracts wire (state A)
If range finder ‘A’ depth returns to 8ft, then servo ‘A’ unwinds wire (state C)
If 1000ms since state C and no change in range finder depth, servo raises wire back to eq. (state B)
…essentially this type of code for each sensor and output motor, still open to ways of making relationships between 9 dif. range finders more dependent on each other/ react to changes in neighboring range finders through code
Detailed Drawing:
Drawing 1
Sketch 1
Sketch 2
State Diagram:
Diagram Here


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