Light Drawings

The idea of the project came about as I have always been inclined towards exploring various possibilities using light source. My very initial project as an engineering student involved making a rotary clock using LED’s.

This project aims at making Mechanical structures which create images spatially and temporally using light as the drawing medium. The concept is based on the phenomenon of persistence of vision, which states that the perceptual processes of the retina of the human eye retain an image for a brief moment. Persistence of vision is said to account for the illusion of motion which results when a series of film images are displayed in quick succession, rather than the perception of the individual frames in the series. Taking advantage from this phenomenon I intend to create light drawings using individual LED’s to create a specific path. The project aims at creating light drawings by making quick motions in space using LEDs as the light source.

3D Object
The first prototype that I made, was a simple profile made using a series of LED’s rotated on a motor to form a 3-D object.

Prototype 2

The second prototype was to experiment with different types of mechanisms to create interesting patterns in light and colour.

Pattern created by the mechanism

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After creating these initial prototypes the next task was to think about the final drawing that I wanted to create. After having spent some time trying to think of what I should draw, I decided to concentrate more on the mechanism and let the drawing be unpredictable.

This led me to think of a light sprirograph, and thats what I ended up making. I got the main inner gear and the other rotating gears laser cut at AMS. I made the gears using a trial version of software called Gear Factory, which is a plugin for AutoCad. It allowed me to make the gears easily only by specifying the pitch and the number of teeth for the gear.

The image below shows all the gears cut out from a 1/4″ Plexiglas. I had kept holes in teh gears so that I could position LEDs at different places to get different results.

The image below shows the entire setup with the central gear being powered of a regular DC motor. The speed of the motor was controlled using a regular potentiometer, along with a PNP transistor. One of the major problems here was to make sure that the motor was fixed exactly in the centre of the inner gear.

Also The whole idea of having the LEDS movable did not work out well, as the centrifugal force was too high and would pop out the LED holders very quickly, so I ended up sticking the LED & battery holder directly onto the gear.

Here’s an image just when it started spinning, and you can see the streaks of light forming.

The following image shows only the green LED with a slow shutterspeed capturing the entire spiral.

Using only the red and yellow LEDs gives a different result.

And this one is with all the LEDs together. 🙂

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Mousetrap Car

Last week the assignment for the Mechanisms class was to make a mousetrap car. A mechanical car that is powered by the spring of a mouse trap. The objective was to compete in a race over 10 feet. I worked with Vikram on this assignment, and we came up with what’s shown below. It uses three bearings(two at the back and one in the front). The mousetrap’s spring is attached to a nylon thread, which in turn is wound around the axle of the rear wheels. Hence once the mousetrap is tripped, it pulls the thread and in turn makes the car go forward.
Car

As our car was made in wood, it had become too heavy to gain initial speed, so we tried reducing as much weight as possible by making cut outs in the wheels. Other problems faced during the assignment include:

1) Finding the right sized shaft for the bearings
2) Attaching the bearings to the chassis and the shaft to the bearings.

Although we lost the race, we were pretty satisfied with our car. (Am sure if it had been a race over 15 feet we would have won 😦 )

Top view

Rube Goldberg Machine

Last week we had our first assignment for the Mechanisms class, where in we were supposed to make a Rube Goldberg machine(Similar to the popular Honda Ad) which would have five energy transfers from the point where you initiate the system and eventual would crack an egg!!! Another requirement was that complete egg should be collected in a container with not more than 50% of the egg shell.

On the first day of our group meeting we all started coming up with ideas as to what we wanted to do for it, everyone had really great ideas, which involved everything from lighting a fire, poping a balloon, using water somehow etc.

Below is the photograph of one of the mechanisms that I worked on. It is necessarily an energy amplifier, wherein one incoming marbel would cause more number of marbels to be released. At this point we werent sure have we were going to get that first marbel and also what we were going to do with so many marbels, but none the less we had this thing working.

Energy amplifier

So after having finished this, our final mechanism came into place, the following two videos show the explaination of the mechanism and working run of the same.

And here’s one of the working run’s of the machine. We broke many eggs that day, but I only managed to take a video of one run 😦