Ir Rays

A few posts before I mentioned our amazement at the strength and penetration of the infrared LED's that we are using as the beacon for our performance. I just took a screen grab of what the webcam was recording as proof that I was not seeing visions. You can clearly see the veins on the hand. I really like the shot. It reminds me of the photograms of László Moholy-Nagy

"The reality of our century is technology: the invention, construction and maintenance of machines. To be a user of machines is to be of the spirit of this century. Machines have replaced the transcendental spiritualism of past eras."
--László Moholy-Nagy

Out of Sight

A few more days and we will be driving up the east coast to NY. I hate to think of all the gas we will burn, but I am sure it will be less than taking a plane, no to mention the cost. Nowadays it is impossible (and this is good) to do anything without minding the consequences in the bigger picture of life as we know it. I feel that finally a swell of inconformity is rising against the many tyrants that rule our world, including our inner one.

Back to business. The weight of the eyes proved too much for the tiny springs, so I decided to encase the spring inside a sturdier one and on top of that I put a couple of coats of latex to hold it together and still be flexible. That proved an overkill. The eyes became too stiff and did not respond to the movement as expected. So I carved them from an ultralight foam, and gave the a few coats of liquid gesso. After sanding them they had just the right look and weight to be supported by the tiny springs.

On the left the amputated wooden eye vs. the light foam eyeballs shown at the end of the spring. The toothpick became the optic nerve and it is passively string-controlled for the basic position and orientation of the eyes. They work beautifully and add a lot of expressiveness. The strings are connected to the end of the neck, so that when the Creator bows its head or kneels, the eyes "relax", and when he stands up they perk up very nicely. As everything puppetry and theatrical, their exaggerated irritation is understandable, given the great effort to see and make sense of an utterly absurd world.

The focal point of the entire universe of the Creator is ultimately its creature. Regardless of the external appearance, which only a parent would love, the important thing is that which radiates from it and communicates its presence. This electronic soul is extremely simple yet fascinating. We started creating the tracking beacon using standard IR (infrared) LED's. We were having problems achieving the necessary brightness to be detected at a long distance. On top of that, since the creature moves around the stage wildly shaking every part of its body and sometimes lowering its head it was important that the beacon be visible in all circumstances. Adding the half-pong ball (sanded to paper thin) helped the angle spread of the light but we thought that it would cut the light considerably.

And indeed our first tests confirmed that. So we bought the super-wide angle IR LED's in the hope of solving the angle problem and still retaining the strength of the light. (see the previous post on that here)


Now comes the ignoramus part, which if we had done a little more research would have been avoided. All the webcams we tested have an internal filter that blocks IR, not exactly sure why (have not had a minute to explore that). So we proceeded to dismantle the lenses to remove such filters. (unfortunately we were so engrossed in doing so that I forgot to take pictures of the process!) This tested every sense and the steadiness of our hands, not to mention memorizing the order and orientation of every microlens. In fact, in the case of our wide-angle camera shown previously, after removing the IR blocker, we had to rearrange all 9 lenses and spacers in any imaginable way until we hit on the right one. Philip which has much better eyesight ended doing the final assemblies and it was nerve wracking to watch, almost like a brain surgeon removing a micro tumor.

The original beacon, which we will use as a backup since it is even brighter because it has more LED's to begin with.

Well, then we were up for a big surprise, in fact we are still amazed at what we saw. First of all, the camera with the exposed film in place (to filter most of the visible light) not only saw the light, but it was as bright as pointing the camera to the sun! At this point we realized that both the standard LED's as well as the wide-angle ones work practically the same. You could turn the beacon even 180 degrees (in other words showing the back) and the camera would still see it very brightly.

But then we were in shock. By holding the IR device in our hand we observe something amazing. We could not only see the light going through our hand, we could see every vein as well! very much like x-rays, except we could not see the bones. Again, the surprise was such that I forgot to take pictures of this, but tomorrow I will. We even put the thing inside our mouth, but the cheeks were way to thin for the strength of the light. This immediately brought questions about the safety of this light which we had not considered.

So I have been reading papers and reports by organizations such as The International Commission on Non-Ionizing Radiation Protection, but have found little indication of danger at that level. However, although LED's are classified as IR-C are supposed to have a minimal penetration of the skin, while IR-A which is labeled as hazardous is said to penetrate the skin only a few millimeters. So something is odd here. More food for thought.

IR Beacon

This is the first finished beacon. It has 24 IR (infrared) LED's. The idea was that, since the tracking camera must have a wide angle in order to see the entire stage (which is about 6x6 meters, much smaller than I expected) from above, we needed an array big enough that would be easily tracked.

What I did not realize was that the angle of the LED's that I got was extremely narrow, so that when the performer lowers or tilts her head (the beacon is on top of her head) the LED's practically disappear. So we came up with the idea of using a diffusion dome to spread the light. That of course is half a ping-pong ball which happened to have the exact required diameter.

The ball was too thick and did not let enough light through, so I sanded it until it felt like a turtle egg, if you ever touched one. The solution worked, however there was still a considerable loss of light.

So I started to look for new LED's. This time I made sure that the lens of the LED would be wide enough to allow the free movement of the performer's head. This is what I found:

Ultra Wide Angle IR 850nm

These LED's are awesome. We could not believe how wide they emit light and how bright they are. You can almost turn the away from the camera and you can still see them!. So they will definitely do the trick without the need for a diffuser. We will use a set of ten which has the added benefit of resulting in a much smaller device and, because it is IR, it will be invisible to the audience.

I bought them form the guys at NaturalPoint which have a wide (yes, intended) variety of optical devices, mostly for motion-tracking. A set of ten cost me US$ 15 which is about half of the price of "cheap" LED's at RadioCrap.

So now we will design and burn another circuit and probably use a coin battery instead, to make everything really compact and unobtrusive to wear.

As soon as the UI (user interface) is ready for the tracking and motion-assigning program I will post pics of the UI and the tracking screen which is a lot of fun to see in operation.

Sense and sensibility and the Oneironaut

Visualizing the user interface for servo control

The nervous system is the current step (by step). Working on the sensors and on the beacons has given me a clearer understanding that there is nothing I know. Still very very far from The Docta Ignorantia.

Here is our microprocessor stack composed of two Make boards which were our final choice. The boards are highly integrated, very easy to interface and simply well designed. The only drawback was the limitation of 4 servo ports per board. I decided early on that 8 motors were as many as I wanted to use, both for practical and symbolic reasons. Four is the symbol of man generated by the trilogy which comes from the duality contained in the unity (bear with me, it is a stream of thought). 8 represents the power of the king in chess, and the queen in all her potency and (coming down to earth), I could only afford two Make controllers anyway! So, there. I had to do it with only 8 motors, period.

Then came the IR beacon circuit. That was a lot of fun to build although it took a lot of trial and error to do it with kitchen stuff. DYI instructions stipulate in no uncertain terms that you should use glossy inkjet paper and ONLY print with a laser printer, then iron transfer into the copper plate. Well, after many frustrating trials, botched plates and burnt fingers we (Philip and I) decided to try swhat you are not supposed to do. Went to our local print shop and had the circuit printed on their glossiest color laser paper with their fancy color printers. That worked beautifully. It transfered absolutely perfect the first time around. The entire coating of the paper stuck to the plate, and I am sure more than one has though that was wrong, but after soaking it in warm water the paper peeled off like a decal and left an impecable mask.

So here is Philip, which was the instigator of the whole DYI circuit idea cooking up the circuit with a coctel of muriatic acid mixed with hydrogen peroxide. In a few minutes our circuit was done. As usual he is multitasking with his totally hacked IPhone.

Guess where Philip is from...

Philip in my studio dremelin the circuit holes while Castro look approvingly at our socialist methodology.

He got a kick out of my retro-futuristic glasses. You look awful in them, but they have a variable focus that allows you to magnify minute stuff or read a newspaper across the room.

This section needs proofing and revising...tomorrow, after I give my class and deal with insane bureaucracy.

After dealing with the obvious and easy choices, like the arms (4 motors there) I realized the problem. My monster servo would lower the body, yes. But what about the head?, the shoulder strings? (they allow the marionette to turn the upper part of the body to face in another direction). They had to be lowered at the same time! otherwise I would need many more motors and complex programming to synchronize all these elements.

So the idea of the elevator was born, with all its ancillary problems, weight, friction, balance, stability, randomness, etc. At first I built tracks to guide the (square!) rods up and down. These rods (quads?) support a platform that houses the 3 remaining servos. The problem is that the head has more than one degree of freedom of course. It not only has to turn left and right, it also has to tilt sideways and bow as well. Or pitch, yaw and roll if you will.

All these simple motions are trivial (if difficult to master) in a marionette. Then I had the shoulder controls to turn the body around; how to do all that with 3 servos and control the wanted nuances?

After about two weeks (which is the time I have not posted!) I stumbled upon the solution, where but in a dream!. It is pretty obvious that we work as hard in our oneiric universe as we do in our waking world.

Next morning I skeptically went to examine the contraption with the suspicion that, like many other "great ideas" conceived in la-la land it would turn to be impractical, impossible or just plain turdy. It actually took me a while to connect my ideas with the reality of the mechanics, something was missing which I had apparently forgotten. Then, all of a sudden I saw it! make one of the servos perform double duty.

I cannot even explain how I visualized it. It was so obvious, simple, and yes, elegant. The only bummer is that I feel it did not come from me but from the collective unconscious debris. I just picked up the pieces.

I will post some pictures to explain how it works.