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Project Log 3: Thinking a lot

A project log for DIY Full-body VR Rigid Haptic Piezoelectric Suit

Cheap Piezoeletric crystals could be used both as movement sensors and vibrational haptic simulators.

FulanoDetailFulanoDetail 09/26/2022 at 22:400 Comments
Today is Monday, 26 of September, 18:47 Brasilia Timezone.

Well, s***, I decided to make at least some kind of 3D model, but it took me too much time.

I feel particularly disappointed with myself, specially since instead of making everything from scratch on Blender (free program with a ton of tutorials on youtube), I searched for free 3D models of some things. I feel like I didn't put enough effort on it...

Of course, all of these models look like... Acceptable things that are freely accessible, the good part is that they are normally low poly, so my potato PC doesn't choke.

OH YEAH! There is also that: my current computer probably won't be able to withstand the processing load of even rendering a VR scene.
Isn't that a really important thing to think about before buying 200 units of piezoelectrics for a goddamn VR suit?
Isn't that the mind of an idiot?

Yes, I found pretty ones, but they need paid programs to even be opened (which I don't have).

Well, anyway, let's discuss about a problem that I just conceived today:


Vibration cancellation for neighbourhood piezosensors:

You see, since every piezoelectric actuator and sensor (they are the same thing, you just use/wire them differently), will be really close to each other, and both work on the principle of vibration/pressure...
How do you avoid the actuators from activating the sensors?

Maybe you could apply a tolerance range of detection on the sensors and a maximum range of vibrations on the actuators. So they don't start feeding each other endlessly. However, for now I can't tell if this will be enough.

You see, it could be fine for the legs and arms, since they usually would make quite strong movements anyway. The problem is on the hands.
They are very delicate and quite sensible to texture, and if you read all the logs from beginning to end, you would know that using piezoelectric crystals, you could create textures with different vibrations.

It will be really necessary to strike a balance between the precision of the movement of the hands and the tactile texture of the haptic feedback, or else everybody hands will be shaking all around in the virtual world.

Not to mention that the piezoelectric "coins" (as shown in the image above) aren't small enough to fit the shape of the hand, meaning that I will have to cut them to size; Which could destroy a lot of them.

There is also the detail that the entire body will be held in place, what could lead to a big discomfort for the users. Imagine trying to walk, run or carry objects on the virtual world and not moving at all in real life? Wouldn't that need some padding?

This could completely nullify the vibrational haptic feedback from the suit.

Okay, maybe you could get around this with those cheap and small vibration electric motors you normally see on Playstation controllers. And maybe you could program the piezoelectric crystals inside the padding by detecting the vibrational frequency that they produce.

Another idea for the cancellation of the vibration is to make a series of switching piezo-roles, so to speak. One piezo-actuator, one piezo-sensor and so on. But adding a little big of some kind of padding between them, like polyurethane (or just silicon).

In resume, Polyurethane is a widely used material that can be tweeked to do almost everything, from shock absorbents (that are used to protect space rocket equipment) to soundproofing, thermoinsulating and fireproofing things (again, there is an incredibly amount of varieties and the ones that you buy may not do all of these things).

Good polyurethane is normally expensive as f*** (in my country [Brazil]), but you could find them in the form of liquids that can become rubber-like bushings, foams and even modelling kits on the internet. And they are quite efficient as well; I saw videos of people literally using polyurethane from less than 25$ for mechanical car pieces, in specific on transmission mounts.
There is also the expansive polyurethane sprays that are even cheaper and can be found anywhere, your house's insulation is probably made of it, actually.

However, there is another thing concerning me: the lower part of the body.

You know, the lower part of your thighs, legs, butt and back. The ones that will be resting and constantly applying pressure on the piezoelectrics.

Okay, maybe if they are constantly being applied pressure, that could mean that you could just ignore this pressure and focus on the differences that will surge during body movement.

Well, obviously I can't say with certainty if such things will have a big influence on the piezos or not, maybe the biggest part of my concerns can be solved with a simple calibration process.

In fact, I'm hoping that you could make multiple layers of piezos instead of putting every single one side-by-side.

And my god, the wire management... 200 piezos to wire... ugh...

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