Friday, March 31, 2006

Get your motors running...

Servo-Motor Prototype

To test the mechanical system using a servomotor as the means of motion, I first had to program a PIC 18F542-ip with a basic pulse width modulation program. To that I added a pot to stand in for my IR sensor. The pot makes it easy to control the servo, and therefore the action of my quills. The linkage is a bit kludgey, but I was able to get a good feel for the potential of the servo.

In comparison with the selinoid, the servo obviously offers a greater range of motion, but the conversion from rotary motion to linear adds a little more complexity to the system. I fear this complexity—it adds to the list of things that can potentially fail. The servo I’m currently testing with is also larger than desired, so I will be sourcing smaller motors, and Danny Rozin has graciously pointed me to some of his sources.

On the positive side, the ability to finely control the position and speed of the servo offers opportunities that the selinoid didn’t. Combining the analog input of the IR sensor with the servo, I can control the deployment of the quills to correspond to the interaction of the PSS and its surroundings: if the IR detects a slowly approaching person, the servo can raise the quills slowly; if the person approaches quickly, the quills are raised rapidly. If the person backs away, the quills can “relax” and lower. This might lead to a more interesting interaction, creating a chance to play with the boundaries of personal space. The servo also allows the quills to stay deployed for as long as needed; most selinoids have a very limited amount of time that they can be powered, therefore the quill deployment would be limited as well.

The prototype also revealed the limitations of my parallel plan concept for articulation. It might be worthwhile to investigate a hinging or axeled rotation.


Saturday, March 25, 2006

Final project

I am proposing a garment that plays with our conceptions and perceptions of personal space. The garment will defend personal space when it is under threat of intrusion, questioning our notion of “ownership” over personal space. Like a cat raising its fur or a porcupine its quills, the garment will deploy an array of “spikes” to ward off invaders. The “spikes” both increase the physical space that is under the wearer’s occupation, but also serve as a visual deterrent to encroachment. The system will work by sensing the proximity of objects surrounding the garment, and will trigger a response when an object or body comes too close. The system will be based on a microprocessor, at least one sensor, and a mechanical system to deploy the array of spikes. At this point I have yet to decide if the garment will be comprised of multiple self-contained systems, or one large system with multiple sensors, and multiple spike arrays.

Videos of prototypes:



Sensors under evaluation:

Sharp GP2Y0A02YK — Infrared send and receive

Quantum Research QT113 — proximity sensor

Photo Cell – light sensitive resistor

spike subsystem:

mechanical –

Spike material —

Plastic brush bristles

Steel rod

Actuator –

Selinoid push

Steper motor

Servo motor

Pneumatic —

Spike material


Plastic sheet, heat-sealed

Actuators –

Selinoid valve

Air tank (air duster)

Compressed gas (co2 canister)

Air Bladder (inner tube)


Pic #?


9volt cell

Yo, Taxi!

New Yorkers hail a lot of cabs, and it can become quite competitive at rush hour when it’s raining, or late at night when bars and nightclubs close. This battle forces New Yorkers to risk their lives wading into oncoming traffic, frantically trying to get a cabbie’s attention. To give the stylish New Yorker the upper hand, I’ve developed Yo, Taxi!, a design that is sure to stop a Yellow Cab in its tracks.

Yo, Taxi! is a coat embedded with a persistence of vision display, shown through a single row of LEDs positioned in the cuff of the coat. When the wearer raises his or her hand and begins waving it in the natural taxi hailing gesture, the LEDs illuminate. The POV strobes in time with the wearer’s action, creating the illusion of the word “TAXI” floating in mid-air.