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The mounted projector
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Projector Loquens
2005
by Eunsu Kang - http://www.kangeunsu.com/
Project Description:
The Motion Tracking Projector is an interactive device that follows a moving body in a space, interprets their behavior by means of a few simple criteria, and projects different images and video onto the body according to its behavior. Motion tracking is achieved with several ultrasonic distance measuring sensors placed just beneath the projector. Information from the sensors is read through a custom Teleo module into a program written in Max/MSP. This program then translates the sensor input into information which is sent to a motor, by means of a Teleo 2 Amp Motor Controller, that rotates the platform with the projector on it, allowing the projector to follow the moving body.
Several elements of this project present more-difficult-than-usual kinds of problems:
The first is that it's very difficult to work with ultrasonic distance measuring sensors with Teleo. Ultrasonic distance measuring sensors use very quick pulses to communicate the distance of an object in front of them. These pulses can take place on a microsecond timescale while the latency of the Teleo network in getting messages back to the computer can be up to about 20 milliseconds. Thus, a custom Teleo module was necessary that could track these pulses with the microcontroller onboard - much quicker than sending the information over the network to the computer and having the controlling software interpret them.
Secondly, the mechanical requirements of this project were relatively demanding. An appropriately powerful motor had to be selected in order to ensure that the platform could be accelerated and decelerated accurately. A limit switch system was necessary to limit the range of rotation for the motor - protruding screws on the shaft actuate mounted switches surrounding the shaft giving the Motor Controller feedback about the position of the shaft and telling it when it has reached the limit of its rotation. |
