It is Wednesday my dudes² 16:53 07/12/2022

So, let's try again, and this time I wll make a list of what I want to calculate first, so I don't just give up on writting this damn thing:

1. Calculate the force generated by the High displacement artificial muscle.
2. Calculate the amount of fluid flow all these muscles will need.
3. Scratch the surface of power supply and liquid used, I feel like powering up 72 groups of muscles will require an absurd amount of liquid flow.

Edit: I think I didn't calculate anything correctly, so the values can be waaaay wrong or simply aren't meant to give the strength. I will only know if I actually make one of these personally.

So, I left the last Project Log giving up on calculating the High Displacement muscles, here is their article, and here is the image:

These need a smaller amount of pressure to work, producing 120 and 300 N at pressures of 35 and 105 kPa (5 and 15 PSI or 0,3 and 1 bar respectively).

So, I got the idea of using this online Circle Length Calculator to calculate the approximate length of the flat hose when deflated.

So, assuming the 2 inch description of the flat hose means the hose reaches 2 inches of diameter when round, the calculator says it has 15.9 cm of length.

Since the hose is folded on itself, I will round up its deflated length to ±7 cm. Like I said, I don't really need the hose anymore, as shown in the illustration of the article itself, I just need to make pouches.

• CR (%) = Δk/k0 x 100

"where k0 is the initial length of the actuator and Δk is the length it shortens during contraction."

Well, I can't tell how much it shortens because I don't have a prototype to test it out, so I will assume that there is 30% of contraction (the paper says it achieves 30-65%) and the full length is 30 cm and 20 cm of width (in the "Y" direction/axis).

But I will try to calculate the contraction rate of a single hose so I can have an idea of how many of these I will need on each muscle.

• CR% = 1.92/7 x 100
• Therefore: 27.4%

Oh, interesting, 27% for a single hose on the horizontal? I thought it would be 1% or less. Bruh

From the article:

"Outer Actuator Modeling
We first model the outer actuator, with the diagram and variables in Figure 6B. The inner actuator pushes on the middle portion of the outer actuator over a rectangular cross section, with a total outward force (F.out), where:

F.out = PhL

and P is the pressure inside the inner actuator, h is the width of the inner and outer actuators, and L is the height of the rectangle where the inner actuator connects to the outer actuator. If the actuator is made from a textile or other material that can bend, the simple actuator model in Figure 6B is not perfectly accurate at its ends. In this case, the region where the inner actuator connects to the outer actuator is not flat, but is a curved surface (Figures 6C,E,F), which results in an effective reduction in the inner actuator's height (L) and width (H) when the actuator is pressurized. Paulsen modeled the shape of a circular pouch (a Mylar balloon) when it is inflated, finding that the radius of an inflated pouch is about 0.7627 times the uninflated radius (Paulsen, 1994).

Let's calculate.

As said before, the pressure inside these are 15 PSI, I don't know if they are saying width in the direction it expands or the "depth" of the actuator, so I will go with the first: 2 inches/5,08cm and since this is a circle, the length will also be 2 inches.

• F.out = 15 x 5,08 x 5,08
• Therefore: 387.096

Is this newtons? They never say that, lol.

So this single hose actuator can lift 39,4kg/86,8lbs?!

Bruh, I feel like I'm mistaking something.

While our pouches are rectangular instead of circular, the center of each side matches the model closely: we performed measurements of sample pouches and found they match Paulsen's model within 1%. Therefore, the true outward force of the inner actuator is based on a reduced cross-sectional area, where the effective height (L) and width (h) of the inner actuator are then Lcorrection = 0.7627l, and hcorrection = 0.7627h. Thus, for inner actuators with flexible ends, the actual F.out highlighted in red (Figure 6F) is:

F.out = PhcorrectionLcorrection

Sooooo... I have to multiply or divide these decimal numbers by the numbers I have? hmm

I will try the following:

• F.out = 15 x (5,08 x 0.7627) x 1 x 0.7627)
• Therefore: 225.178113514

22kg/50,6lbs of force, still huge for a single cutaway of a hose, bruh.

The L is the height in wich the inner actuator connects to the outer layer, so maybe that is why the previous number was so high.

So, let's say it is a height of 6cm, so there is a space of 1cm above and below:

• F.out = 15 x (5.08 x 0.7627) x (6 x 0.7627)
• Therefore: 265.9

It got higher, lol

Well, what if I put it between parents instead of "x"?

• F.out = 15((5.08(0.7627))(6(0.7627)))
• Therefore: 265.9

It is the same result, lol

Let's get this bread, I will try to calculate a single muscle with multiple hoses one in front of other and above of other, so it has more area to work with.

However, the article doesn't that that into consideration (I think), so I will maybe need to multiply the result of a single horizontal line by the number of muscle "cells" on each layer.

Another matter is that the illustration is just a illustration, I will try to fit everything at 30 cm as close as possible.

I will try to get the width of each deflated flat hose to be 2cm of width and 7cm of length, inflated it will be 5,08 x number of hoses in line = 20.32cm.
I will assume a height of 6cm, so 1cm above the "bone" and 1cm below the "shoulder bone".

• F.out = PhL
• 15 x (20.32 x 0.7627) x (6 x 0.7627)
• Therefore: 1063.83360715
• If there is 5 of them: 5319.16803575
• Newton to Kg = 542.4
• Newton to Lb = 1195.7

So I would need 2 of those in order to lift 1 ton, which means I would need 10 of those in an arm to apply a force of 5 ton.

But wait, this doesn't take into consideration the "depth" of the pouches, nor that you're not limited by 15 PSI.

If I multiply the final result by the length on something around 2 or 20cm, I can achieve 1 ton easily. Not to mention that if you multiply by, let's say, 35 or 100 PSI, you will get:

• 35 x (20.32 x 0.7627) x (6 x 0.7627) = 2482.27841669 = 253kg = 558lbs
• 100 x (20.32 x 0.7627) x (6 x 0.7627) = 7092.22404768 = 723kg = 1594lbs

Almost at 1 ton, I think it can do it.

---

How much hydraulic oil this would need?

Well... Sigh... I will try to figure out how much this would need.

I will try to find a calculator for that.

And guess what? There is one, lol.

I will insert the diameter to be 5.08cm, the length to be 20cm and the density to be 0.9 g/ml accordingly to google.

The result is 0.405 liters and 0.36kg (0,79lb) of mass.

So, since I need to feed 20 of those for each ±30cm muscle, so I would need to feed 8.1 liters of oil in a single muscle, which would weight 7.02 kg (15,4 lbs) when fully inflated.

And since I will have 72 groups of thos with at least 5 of them in each, I would have to flow and weight:

• (8.1 x 5) x 72 = 2916 liters of volume.
• (7.02 x 5) x 72 = 2527.2 kg (5571 lbs) of mass.
• This doesn't take pressure into consideration.

I'm completly fine.

Well, I can make other numbers into consideration.

For example, I could simply reduce the number of muscles per group.

like a single one for each 72 muscles.

• 8.1 x 72 = 583.2 liters
• 7.02 x 72 = 505.44 kg (1113,33 lbs)

Concerning, but not that extreme as the previous one. 

Recalculating. Again.

Ok, I believe I will need to recalculate again. Because the paper says a lot about width, length and height, which got me confused. So I will take the following image into consideration:

• F.out = PhL (of single cell, then it will multiply it by 5 cells and then more 5 cells, so a 5x5 grid)
• 15 x (20 x 0.7627) x (6 x 0.7627) = 1047 Newton = 106.7kg = 235.3lbs
• 100 x (20 x 0.7627) x (6 x 0.7627) = 6980 Newton = 711 kg = 1569 lbs
• Since there is 5 of them in line horizontally at 15 PSI = 5235 Newton = 533kg = 1176lbs
• At 100 PSI = 34900 Newton = 3558 kg = 7845 lbs
• And since there is 5 lines of them one above the other (15 PSI) = 26175 Newton = 2669kg = 5884lbs.
• At 100 PSI = 174500 Newton = 17794kg = 39229lbs.
• Now calculating the volume: ((0.405 x 5) x 5) x 72 = 729 liters
• Mass: ((0.36 x 5) x 5) x 72 = 648kg = 1428,6 lbs
• Okay, this is way better.

Also, I just noticed that if it was bars on in Mpa instead of PSI, it would be a completly different result, I wonder if this mess of equations I've made are even remotely correct...

Edit²:
So, I just noticed that normally they refer to pressure as "Kpa", so the value of "100 PSI" that I've been inputing is probably 100 Kpa, which is just 14,5 PSI, so If I was to actually apply 100 PSI, I would be reaching values of 689,4 Kpa. Which would reach 1 203 095 Newtons = 122 681 kg = 270 466 lbs.

Of course, assuming nothing gets rips apart by the sheer forces involved.

Edit³:

I forgot to calculate the volume and mass of the muscles if these were conventional McKibben muscles.

One tube with 2 inches (5,08cm) diameter and 30 cm length would have 0.608 liters of hydraulic oil and 0.55 kg of mass in a single McKibben hydraulic muscle.

Since there is ten of those for each one of 72 groups of muscles, we would have 437.76 liters of oil and 396 kg of mass.

Well... This seems way better than the high displacement artificial muscle, and the best part is that I don't need to actively and completely pump the oil out of the muscles like the High Displacement one.

But just now I remembered that I would need to use 5 tons for each ton I need to lift at the tip of the limps.
If it was 50 muscles for each one of the 72 groups, it would be 2188 liters and 1980 kg of mass.

Well... sh*t.

How to calculate the amount of flow?

Seriously, I don't know.

I will try by taking these 729 liters for a third of a second, the time/speed I want these things to contract. So 2187 liters per second.

So, since the flow rate is calculated as liter per minute, I would need 131 220 liters per minute.

Obviously, not all muscles would be contracted at same time, but if they were, this would be the maximum value they would need.

So, accordingly to this flow rate calculator, Inside a 25mm diameter hose, with maximum length of 4 meters, I would need 5-6 bars/87 PSI/0,6 Mpa of pressure in order to achieve 131 220 ltrs/min.

Which is not that much actually (I hope), not to mention that I hope to have a fluid pump for every limb (torso+arm1+arm2+leg1+leg2), so I would need 5 to 6 pumps with 12v that can achieve 60 PSI.

But oil pump extractors with 12 volt can achieve 0.8 Mpa way above what each limp will need. I found a random one that uses 45 watts, so 5 or even 6 of these would suck 225-270 watts (maybe per hour).

I could easily power that with 4 or 5 small battery packs used for electric car toys for each pump  would be able to supply them for a few hours, accordingly to this google result, batteries normally lasts to 50-100 hours. lol

Again, some things may not work properly in real life, so...

This doesn't take the progressively magnetic active valves energy consumption into consideration (the ones I talked about on Project Log 4.

Edit⁴:

I forgot to take into consideration that hydraulic oil has a different viscosity than water, so the oil pumps would need to work in a different manner.

Accordingly to this flow rate calculator that I think it is more precise, if I started with a flow of 0,8 Mpa (produced by the oil pump I talked about), with a pressure of 0,1Mpa at the end of a 4 meter long 25mm diameter wide tube, I would reach 1438,1 l/min.

Which is 91 times less of what I need.

So 72 Mpa/10 442 PSI at the start.

I would need a really heavy duty hydraulic pump to fill a hydraulic accumulator with 700 liters to actuate every muscle once.

... Or not, I could let the muscles partially inflated and use the pressurized flow to draw more fluid to the hoses.

But I don't know how to calculate all of that, so the High Displacement muscle is back to the mind archive.

If it was the McKibben muscles, thus needing to fill up 1313 l/second, this setup would only provide 13 liters per second.

HOWEVER, this would mean that the muscles are completely empty (which isn't the case) and would need to be filled instantaneously, but they wouldn't.
In fact, I would only need them to be filled around 3 times its initial volume to fully actuate them.

So, let's see.

There are 5 limbs, I just need to actuate 3 of them, but let's actuate just one:

437 liters in total divided by 5 = 87.4 liters per limb (more or less).

So in order to provide them with 3 times its initial volume, I would need 262.2 liters/second...

In order to achieve such volumes, I would need a 4mpa oil pump (that uses 220V) and a 2 meter hose, for each limp. And each would consume 1300 W of energy per hour, so 6500 watts per hour in total.

You would need 11 car batteries to power this up to about an hour.

So I guess that's it bois, no hydraulic mechs.

All this work just to comprove the obvious: mechs are not viable. XD

At least hydraulically, I will still be researching for the electromagnetic counter part like I talked about in Project Log 1.

That's it, bois, more wasting time! :D

It is Wednesday my dudes 08:25, 07/12/2022

Well, I'm having some difficulty finding a way of calculating the force of a McKibben artificial muscle.

I can't find a simplified model, nor a general guessing of what kind of force these muscles would be able to apply.
Like I did before in other logs "this video/image shows a muscle with X length Y diameter applying Z force, so I would need W amount of them to lift V kilograms".

But, since I'm not planning on using a conventional style of McKibben muscles, I'm in a little bit of predicament.

Taking into consideration that I'm planning on going on scrapyards and take as many materials as I possibly can, and that I'm also planning on using non-elastic flat hoses as the inner tubing, I don't think that the current McKibben style of muscle will be useful for me.

For example, there is a type of pneumatic muscle that has 65% of contraction that doesn't use inflatable materials, the mere change of shape from flat to round is enough to actuate with very low pressures, just like the flat hose I'm planning on using.

Here is the article, luckily, the article focuses on the modelling of the strength of such muscle. And as you can imagine, these can be made horizontally and vertically.
And they need a smaller amount of pressure to work, producing 120 and 300 N at pressures of 35 and 105 kPa (5 and 15 PSI or 0,3 and 1 bar respectively).

I was actually trying to avoid this type of muscle because they expand a lot, and since there will be 10 or even 50 of those in the same place, and maybe there won't be space left for all the muscles to contract.

Let's try the options I can find and see how well this car crash of a calculation this is.

Attempt 1:

I found this paper here that has the following formula:

I have no idea what the heck this means, but I will try to figure out by reading the article instead of jumping paragraph to paragraph like my ADHD ass normally does.

Maybe using the explanatory image the own article provides could be a good idea, right, myself?! 

So... I will try to use "Letter/number+1" and "Letter/number+2" for decompressed and compressed. The problem is that I don't know what the measurements will be when compressed.

• P1 = 0.
• L1 = 30cm.
• D1 = 2 inches (5,08 cm).
• 01 (the weird zero) is about the braid angle, I don't know yet, I will just use the angle that normally is used on conventional braided sleeve, something between 18 and 11 degrees.
• These "Sin" and "Con" that you see can be added by the scientific calculator, dunno what they mean, but I was kinda puzzled when I first saw them on equations.

The compressed state I will assume it will be the following numbers:

• P2 = 100 PSI
• L2 = Since these normally compress to around 20%, it will be: 24cm
• D2= I also don't know, I will just throw 20%: 1,96 inches (4,97 cm)
• 02 = 45º angle?
• The triangle ∆L symbol (makes the letters bold on hackaday for some reason) is the difference between the initial length and the end length.

So, we can try and throw the following calculation on google scientific calculator:

F = (π × 4.97²2 × 100 ÷ 4 × sin(45)²2)(3(1 - 0.11 ÷ 24)²2 cos(45)²2 - 1)

(I'm using the pressurised numbers, since the result of the equation is the force applied, if the pressure is 0, the force will be 0)

So... the result is, accordingly to google:

-252.387549267

????????

Okay, let's try again, I added multiplication values where there's none, so I will put the number/value between (), so it is automatic multiplication, I think.

The result of:

((π(4.97))²(100 ÷ 4 (sin(45))²))(3(1 - 0.11 ÷ 24)² cos(45)²2 - 1)

Is

-4412.77987695

?!?!?!?!?!?!?!?!?!?!?!??!?!?!?!?!?!?!?!?!?!?!??!?!?!?!?!?!?!?!?!?!?!?

What if I took the "÷" out and added "/" instead, just like in the original equation?

 (π × 4.97²(100/4 × sin(45)²))(3(1 - 0.11/24)² cos(45)²2 - 1)

It gives an error message, lol

If try "((π(4.97))²(100/4 (sin(45))²))(3(1 - 0.11/24)² cos(45)²2 - 1)" it gives the same -4412.

Okay, this is hard.

I tried an online scientific calculators and the result was

19187.13008

And

6011.092667

For the first and second equations.

So I can assume that this is what? 19000 (or 6011) newtons of force? Lbs? Kg?

Because if it is Newtons, it will be 1956.5 (or 612) kilogram force and 43133 (or 1353,64)lbs respectively.

It is probably giving weird results because of minor mistakes I've made.

Now trying the High Displacement actuator I wrote at the beginning of this mess.

• CR (%) = Δk/k0 x 100

"where k0 is the initial length of the actuator and Δk is the length it shortens during contraction."

This is for contraction rate calculation.

Fully expanded is 2 inch, because it is what is said on the description of the flat hose. I don't know what is the diameter and length when flat...

Whatever, I feel like my brain has turned into a mush and I can't concentrate anymore, I will try to calculate it later.

I would need to have it in hands, but... I don't want to buy 50 meter of this stuff just to later let it accumulate dust because I changed my mind with a better idea.

Monday 07:58, 05/12/2022

So, now that I have a 3D sketch/concept, I do want to figure out how everything will need to fit around the fricking mech's body.

Making its body is easy, fitting a human, a power supply, a board computer to control everything and the pressure chambers will be really hard.

I tried to make a really sketchy looking test yesterday on Blender and I only got to fit everything when I scaled it up to around 3 meters, same height as Obsolete's mech (on the wiki it is said they are around 2,55 meters tall).

I also calculated a little bit how much force I would need in the arms in order to lift 1 ton, and basically, I would need to exert a force of 5 tons. So, basically, I'm already needing to multiply the supply costs by 5...

I used this and this mechanical lever calculators, I put 5 cm for the effort arm and 30 cm for the reistant arm on type 3 mechanical lever, obviously, I don't know yet what is the actual size of the final thing, but since it is 2 meters tall, its forearm would easily exceed 30 cm of length.

But if it was the case, it would increase the muscles costs to 400 Reais already... Not as crazy as 6 thousand bucks as the conventional muscles, but expensive nonetheless.

Well, I didn't want to make a exoskeleton, but seeing the costs only increasing and increasing, I may be forced to change the focus of this project to exoskeletons.

After all, as much as I like Mechs, I don't want to just keep going with a project that I think it won't be worth the trouble.

Yes, I know I said that on the project's subtitle: "Mechs aren't viable, nor cheap, so I will try to build one anyway".

But let's just remember that the muscles themselves are the cheap part, not the metal endoskeleton, not the motion capture suit, not the power supply, not the hydraulic pump.

If the suit can't walk without a power supply the size of a house, then this project is useless, don't you think?

And to further the discussion a little more, let's talk a little bit about what I nicknamed (I've never seen this term being used) "human impedance":

The idea of a exoskeleton would be to carry the extra weight the user would need to carry, so their movements and body effort aren't as exhausting.

But if you want an exoskeleton with super human strength, then the exoskeleton doesn't need a human user.
The human user will just get in the way of the exoskeleton because of its squishy meaty fragile body, the Guardian XO, an exoskeleton built to help its user lift 200 pounds (+/- 100 Kg) is this heavy, cluncky piece of equipment that has a lot built into it to just not harm its user.

If you wanted a exoskeleton to give you super human strength and speed and maneuvability, the problems would only attenuate. 

At this point, isn't easier and simpler just take the human out of the "equation"? That's why I say "human impedance".

The more complex it gets, the more you want humans out of the suit and in a safe place, like a cockpit. And worse, instead of the human body sutaining its own weight, now it is almost dead weight on the machine.
But since you're using a exosuit with super human strength and speed, the human strength would be minimal and the suit would need to carry it anyway.

That's why I decided to go with mech, not exoskeleton. But hey, it is my own fault for wanting this thing to lift 1 ton. lol

Edit:

If I wasn't clear enough, let's think this way:

You're not an Olympic athlete, you are sedentary, you never exercise.
And suddenly the spirit of a record braking athlete possesses your body and repeats the same feats they would have done while alive in their well trained body, but with your sedentary body.

What do you think it would happen to your muscles? Your joints? Your bones? Everything would have been destroyed.

Now just replace the part saying "the spirit of an athlete" with "super human exoskeleton". You would have the same results.

Plus, there is another problem that nobody seems to think about exoskeletons: what I call "body on body impact".

So, you're completely covered in metal tubes with sharp edges and no padding at all, you're running and then you stumble and fall.

How much it would hurt?

It would be the same thing as carrying a lot of pieces of metal on your arms and then falling on top of them.

It is the same thing as belly flop on a pool of Lego's, but the Lego's are around your entire body falling with you.

Well, first, let's start downloading a low poly rigged human, so I can actually try to make them fit into the mech.

I found this rigged 3D model for free on Free3D.

I will make them 2 meters tall, because if a 2 meters tall human can fit into a cockpit, anyone can. lol

By the way, you just need to go to "Pose Mode" on blender in order to move these sticks/armatures just like you would do with an object (pressing "G"), for some reason there is a myriad of different ways of doing that.

I will try to make something like a "piggy-back cockpit" on the mech, just like in Obsolete.

You see, that's why I'm stoopid: it just crossed my mind that I should had put the pilot around the mech and then modelled the cockpit instead of doing it on the air...

And obviously, it doesn't fit.

The mech has more or less 2 meters (6 feet) of height, and the human inside has 2 meters of height too, so you can have a perspective on how stupidly big the cockpit is compared to the mech itself.

It is like a giant goofy backpack.

Without the cockpit.

Okay, this looks a little less goofy, still sucks anyway.

Well, I unfortunately had to stay with 2,55 meters tall, or else it just gets goofy looking and akward.

Well, the "only" problem is that now the forearm is 55cm long instead of the "worse" scenario I wrote at the beginning of this Project Log. Of course, I can always shorten them a little bit (I think).

Accordingly to the second lever calculator, if I had a 1 ton (9806 Newtons) load at the tip of a 55cm long forearm, and I had a bundle of muscles at 10cm distance from the fulcrum point, making it a type 2 lever with a load arm of 45cm, I would "merely" need to apply 4499kg (44127 Newtons) of force to reach equilibrium at 90º.

Yes, equilibrium is not necessarily the entire force necessary to lift this weight, if the forearm never reached the 90º degree angle, it would still be able to carry it, not necessarily lift it.

I know that probably for smarter people than me this would seem obvious, but not for me, lololol.

Also, that's why you can't lift a heavy object (like a 20kg package) at the tip of your arms, but you can easily carry it when you support this weight at your shoulder or at your belly.

Another thing I didn't stop to think about it, but I will have 10 or more McKibben muscles on every place that has a "balloon" on the 3D model, will everything fit in there without reach that "too muscular" problem?

Example:

Also, I totally forgot to talk about: the power consumption, this post was meant to talk about the amount of hydraulic fluid, pressure and flow this contraption would required, but I totally forgot, lol

Also² I forgot to talk about the "walking chair" concept, where the cockpit would be the entire torso. I think the idea is cool, but I believe the cockpit would restrain the walking movement and it wouldn't be able to even climb some stairs.

The probable solution would be to either space the legs out like in the Obsolete-like mech or invert the cockpit, but then it would be too reliant on cameras and/or mirrors.

Other solution would be to use chicken-like legs (that I heard are more efficient), but I don't know how intuitive would be to control a chicken mech with your body movement.

Not very comfy.

I tested on vertical too.

Edit:

Normally I would create a new Project Log, since I'm adding this edit 2 days later, but I don't think it will matter much in this case.

I tried other designs, like the walking chair, and I didn't like the results that much...

This does look like a Gurren from the anime Gurren Lagann (as shown bellow) and it does look cool as heck.

The reason I didn't like it is because the legs are too far apart from the center o gravity (the middle of its body), maybe it won't be a big of a deal with a small mech like this, but if you're counting on carrying something around 1 ton, it will definitely affect its balance.

In this attempt I tried exactly to solve that, but the arms are too far apart. I don't even think these would be able to reach the front (where the knees would be).

Edit²:

Tried a new design, I kinda liked this one (I didn't fix the arm distance, I just made this as fast as possible).

Edit³:

I've made these new designs, following the advice of dekutree64 on the comments (I think it was them, I don't remember quite well).

Where the torso should be solid to reduce moving parts and it could house the electronics, power supply etc.

I kinda like how it looks, but like they said, it still needs a little bit of mobility on the torso (also, ignore the arm clipping through the cockpit, and the too protuberant shoulder platforms).

The first from left to right is the 2,55 meters tall version, the second one is the 1,98 meters tall and the third is using the first cockpit design I've mad (that is terrible).

Edit⁴: 

Two on the right are the Dekutree idea: 150mm diameter tubes as torso/support for the arms.
On the left is the same thing, but with a container in front of it, it would contain electronics and the hydraulic pump and whatsoever.

Edit ⁵:

I tried this bucket looking design, lol.
And it is the 2 meters tall mech, by the way, not the 2,55 meters tall.

(and yes, I'm trying to find how to calculate a McKibben muscle, ok? It is just hard y-y)

Sunday 17:28, 04/12/2022

I used my brain a little bit from the last project log and I thought on some things that may or may not be useful for the construction of the artificial muscles.

Well, it just crossed my mind that the rubber flat hoses can be heated, partially melted and reshape it in other forms that are more interesting for an artificial muscle, since they are malleable, but not inflatable. Which is important for McKibben muscles, since its inner tubing is normally inflated.

I can do the same thing for rubber scrap, which didn't cross my mind until now.

Also, for the braiding material, I thought on using duck tape. Yes, gluing two duck tapes on one another and then using them to braid the muscle as shown bellow. Some tapes are crazy resistant, and can even hold dozens of kilograms, specially the duck tape type.

I took the picture from this article: "Experimental Investigation-Natural Fiber Braided Sleeve for Pneumatic Artificial Muscles Actuation".

Also, I took the information of "duck tape being really strong" from this video testing a bunch of tapes:

Sunday 09:28, 04/12/2022

Well, I just woke up and my brain is still on low energy mode, lol.

So, after sleeping like a rock and taking some really useful notes with dekutree64, I decided to lay my options on the table again.

I'm having a hard time trying to find a 1 ton Mckibben muscle that isn't made of Vectran and Kevlar (I wonder why ¬ ¬).

In this video of the channel HackSmith, they make McKibben muscles using steel braiding and rubber balloons. I don't really know where that kind of rubber balloon can be bought, but I will try to find on google shopping.

During 4:47 they show that an 1 inch braided stainless steel pneumatic McKibben muscle (I will use hydraulic, by the way) that accordingly to that goofy look green screen, it lifts 205lbs/92,9Kg, around 100 kg for 1 inch, so I would "only" need 10 of those.

But I'm still watching (re-watching, because let's be honest, every nerd has seen this video), and I'm trying to figure out how much pressure they use.

Well, I finished it and they don't say in any moment, but I can assume that it is around 0,7mpa, or 101,5 PSI, or 6,9 bars (nice).

Edit: I was rewatching today (2 days later) and at 2:44, they show a pressure gauge that stays at more or less 100 PSI or 5-6 bars. So I was right. lol

Also, I saw this question on quora asking "what would happen if you filled half of the artificial muscle interior with something solid".
And basically, it would still apply the same amount of force, but with less fluid. This means that if I filled the interior with plastic (or whatever other material), the muscles wouldn't weight as much as if they had liquid inside.

Maybe I could put a partially filled balloon inside, so it gives a little bit of spring action.

(Also, for some reason when I hyperlinked the phrase to the quora page, it froze the hackaday website and I had to rewrite a bunch of stuff).

So, taking into consideration the 3D sketch I made on Project Log 6 (I updated the 3D model, by the way, I forgot to add some muscles), we can count how many 1 ton group of artificial muscles we would need:

There are 10 Stewart Platforms with 6 muscles each, plus 4 muscles on each arm arms, plus 2 more on each thigh, so we have 72 muscle bundles (without the hands).

So I would need 720 large McKibben muscles, and pretending each is 30 cm long, I would need 216 meters of 1 inch tubing and braiding. Well, better than the 4,4 km. than my previous calculation.

Well, not that much...

You know, the price is proportional to the amount of rubber used, you know (I didn't, because I'm a idiot)? So... I can only find the prices around 20-40 Reais per meter. So 4400-8800 Reais for 220 meters...

LUCKILY I found out that 1-2 inches flat hoses are quite cheap, I can easily find 40 meters for 15 reais, what would be 0,37 brazilian cents per meter. Which would cost 81 reais for 220 meters.

I would need to "just" cramp that beast into a 1-3 inch braided sleeve, and since these can't escape, they would inevitably expand the braided sleeve sideways (I think).

And yes, I think one could use the flat hose alone, since it is flat and once the water pressure increases, it expands radially.
But I don't know how much it contracts compared to an actual McKibben muscle, probably not much.

Also, I don't necessarily need to braided sleeve that normally you see being used on McKibben, one could actually just make one braid using the "chinese finger trap" braid. Even Festo used that method in one of their products to increase contraction up to 45%. But I can't find the PDF again (not that it explained how to do it, just showed the product).

And I say that because braiding can cost up to 20 Reais per meter, and I can't afford that y-y.

I can just buy fabric tapes (like synthetic silk) and use that to make the braids, although I would still need to make everything by hand...

Also, this "solves" another problem that was in my mind when looking for materials:

Once I read a really useful article about a new type of pneumatic muscles, and one of the problems they were trying to solve was exactly about the expansion process.

The expansion of the inner tube and its friction with the outer sleeve diminished a little bit of the efficiency of the artificial muscle.

Just found it: "Third–Generation Pleated Pneumatic Artificial Muscles for Robotic Applications: Development and Comparison with McKibben Muscle".

For some reason I couldn't find the method of fabrication, but basically, they use a specific tissue with a linear triangular "wave", and on the inside of each "wave" they insert a wire of some material.

It is quite simple to make, but not in great quantities.

Also, I can't find the damn pdf anymore with the fabrication method explained. I always download a lot of scientific articles and pdfs "to read later", but now that I have almost 10 gigabytes of this crap I can't find anything anymore.

There are McKibben artificial muscles that are made from ripstop fabrics, and that's something that completely flew over my head while I was writing these Project Logs:
Just using fabrics instead of tubes, that is cheaper (I think) and easier to find.

The only problem is that I need to make the tubing... By hand.

I mean, if I can find a supplier that turns them into tubes with an automatic sewing machine... Or a "melting machine", since these are normally made from polymers.

Let's look at first article: "Simple, Low-Hysteresis, Foldable, Fabric Pneumatic Artificial Muscle".

"Fig. 1. Left: The fPAM (Fabric Pneumatic Artificial Muscle) in a depressurised, folded state. Center: The depressurised, extended state (ε = 0). Right: The pressurized, contracted state as it lifts a 2.3 kg mass. The 30 cm long muscle (without compressor or end fixture) has a mass of only 1 g, and a peak contraction of about 30% when unloaded. Ruler is 30.5 cm long for reference."

Well, this is in the same proportion of size, force and inner pressure as the multifilament Mckibben muscle I showed on Project Log 7, this time however, they've made a endurance test, and this baby can endure thousands upon thousands of cycles of contraction and lifting.

So it is very much working under the threshold for resistance and forces, this mean redundancy and endurance. :)

Now the hard part is finding out how much fabric I need to lift 1 ton. They show how they made this FPAM, but I couldn't find any information on the width of the space cut.

"Fig. 3. Series of photos illustrating fPAM fabrication.
A) Cut fabric at a 45◦ bias.
B) Lay strip of fabric with double-sided tape down its center.
C) Fold top half of fabric over, lengthwise, onto the double-sided tape. Apply thin bead of silicone adhesive along edge of fabric.
D) Fold bottom half of fabric over and adhere to applied silicone adhesive.
E) Apply pressure and wait for adhesive to cure.
F) Evert tube to remove tape and complete manufacturing. Scale bars denote 5 cm."

"Scale bars denote 5 cm", I can't make heads of this, but I will assume the width of the strip in the B figure is more or less 5 cm, lol.

Anyway, I don't think it will be a good idea to use this, it is too time consuming to make this happen, I will keep searching for Fabric McKibben muscles.

Also, I totally forgot about this, but there is a printable pneumatic muscle (that can be used as a hydraulic one that can be mass produced easily as well.

Article is: "Printable pneumatic artificial muscles for anatomy-based humanoid robots".

Well, I'm kinda tired right now, so I will see if it is cheaper later.

Edit:

I'M BACK LESGOOO

Normally I find PET foil bobbins laminated with aluminium foil, just like in the paper. These costs 100-250 meters for 100-200 brazilian bucks.

So, around 2 brazilian bucks per meter, not bad.

The thing is, that these bobbins width is not really the same as the final muscle fiber. The muscles are 5cm in width and 13cm in length.
One example I can find is 250 meters long with 32 of width, so in total, we would have 6,4 muscle fibers by dividing it.

So, having muscle fibers of 30 centimeters length dividing by 250 meters we would have 833 fibers, multiplied by 6, 4998 fibers with 30cm in total. And since every fiber can lift 1-2 kg, we would have the capacity of lifting 9996 kg from 250 Reais of aluminium plated PET sheets.

Although the flat hose McKibben would merely cost 81 reais (15,52 dollars) for all the 220 meters of material, since I need 25 reais for each 1 ton muscle bundle, I would need 1800 reais for all 72 muscle bundles.

Of course, the price can change based on the price of the foil and the type of foil. I tried exactly the type of foil used on the article, if you could find another type of foil that is cheaper than this, I would love to hear, because I really don't wanna make 300 meters of chinese finger trap by hand. lol

Saturday 21:00, 03/12/2022

I'm feeling a little bit better after spending almost a day making Project Log 6, after finishing it I felt like my brain had been deep fried.

So, let's start with the artificial muscles, the multifilament McKibben muscle that I talked about on Project Log 1, you can read their article here.

1kg is the equivalent to 9 Newton, so 16 muscle-fibers of this multifilament can lift 25 Newton (2.54 Kg), and I would prefer to "translate" 16 fibers = 1 Kg merely for redundancy.

So, every fiber in the picture has 280mm of length (28 cm), so just this contraption uses 448 cm of expandable tubing and expandable braid, 4,4 meters for 1kg (of course, the length of each fiber can be shorter and still lift 1kg).

If I want to lift 1000 tons with an artificial biceps muscle, this means I would need  4,4 Km.

And looking at generic silicon tubing sellers on google, I can only find them selling 5 meters or less in one go.
So the price tag for 1 meter is normally 2-3 Reais (my country's currency, more or less 0,38 dollars), so just for this 1 ton lifting muscle with 4,4 km of tubing, I would be paying 8800 Reais on silicon tubing alone...

Oof

Of course, if I contact a supplier, this will maybe get cheaper.

For example, a single purchase on this store from Alibaba of 5000 "units" (1 unit = 1 meter), I would be paying 1000 dollars for 5Km, which is... 5219,40 Reais...
Well, if I need more than 100 muscles, I would need at least 1000 more silicone tubing, which it would probably make it a little more cheaper, but not that much.

Obviously, I can always screw redundancy and cut the value to 2500 Reais (500 dollars) more or less. I'm trying to build redundancy on redundancy, which may not be a good idea.

For comparisson, a hydraulic mechanical jack that can lift 2 ton costs merely 70 brazilian bucks.

And you still could modify these to be electrically operated or accept "hydraulic juice" from another source that isn't the crank shaft.

I wish I could see more information about the weight, internal pressure and things like that, but for some reason no one lists it.

But they weight merely 2 kg (from what the sellers say).

I couldn't find these cylinders being sold without the crank, or cylinders with the same strength.

For some reason they are super ultra expensive, and when they aren't expensive, the shipment fee is around 1000 Reais.

Oh well... I feel like I (like I'm dumb) underestimated the price tag of these kinds of stuff... That's why I'm making this Project log in the first place, because I knew I would be underestimating prices.

Initially I thought the problem was the "Solenoid Creep", and then I thought that artificial muscles would be dirty cheap compared to conventional actuators like electric motors and hydraulic cylinders...

And I don't think I will be able to "just" cut the amount of tubing necessary for 1 ton, because wanting it or not, I will need to lift this much when the entire thing is moving around, walking and running...

Well, I will need to thing in another type of actuator, or another material that can be used to make the artificial muscles.

Or simply use the cheap and readly available hydraulic jack actuators.

(this image is to myself btw)

Why I'm so fixated on artificial muscles?

Anyway, my brain is fried to a krisp, I'm just going to sleep now...

Friday, 13:25, 02/12/2022 - Yes, "02/12", it took my two days to finish this Project Log since I had to rewrite it time and time again.
At first I thought this was a waste of time, but after doing this, I feel like I have a better idea of what I need to do.

So, I will try to design the endoskeleton of the mech right away, and I believe it will be relatively easy to do since I will be using parts from cars and other vehicles, so maybe I can build something on a open-source 3D modelling program called Blender (since it is free, it has a lot of useful tutorials).

Of course, designing something is easy, designing something that won't break is the hard part.

I hope I can first find the parts and the sizes that I will need so I can actually estimate how much weight and impact these parts would need to withstand. It is easier to find an answer around the internet when you ask something more specific like "Can this shock absorber from the model xxxxx9 be able to support 500Kg vertically, or do I need something different?".

So what we need?

First, let's start by the parts that will actually hold the most amount of weight:

The torso, the waist/hips, thighs, legs and feet.

I was searching for scientific articles that studied and designed humanoid/anthropomorphic body parts for robots, and I found some interesting things.

The article is "Design and simulation of a waist–trunk system for a humanoid robot" (you may need to use Sci-hub in order to see it, but google images shows its images anyway for some reason).

What it uses is a 6 degrees of freedom Stewart platform above a weird 3 degrees of freedom parallel manipulator.

It is called 6 degrees of freedom and 3 degrees of freedom respectively because:

"It refers to the six mechanical degrees of freedom of movement of a rigid body in three-dimensional space. Specifically, the body is free to change position as forward/backward (surge), up/down (heave), left/right (sway) translation in three perpendicular axes, combined with changes in orientation through rotation about three perpendicular axes, often termed yaw (normal axis), pitch (transverse axis), and roll (longitudinal axis).
Three degrees of freedom (3DOF), a term often used in the context of virtual reality, typically refers to tracking of rotational motion only: pitch, yaw, and roll."

Of course, since the actuators we will be using are soft actuators/artificial muscles, it will be a pull actuation instead of a push actuation like in common hydraulic cylinders. And it needs to be hydraulic becase of the variable viscosity fluid that we need for the progressive active valves, as explained in Project Log 4 (the correct name is "Magnetorheological Fluid" for such liquid).

And since the actuators of the Stewart Platform we will be building can expand without an extra mechanism in the already complex mechanism, it won't be able to go up and down. Not that this is a problem, after all, we can't do the same movement with or spine or shoulders.

This soft actuator Stewart Platform is from this paper: "A Pneumatically Driven Stewart Platform Used as Fault Detection Device".

Notice that the center has a big spring, so the platform can either contract or relax, allowing the spring to do such motion. I don't think you would really need such spring, but I think it could be a fine addition in the center and around the muscles; Since I do want a little bit of mechanical compliance from the mechanisms, so they don't go breaking other people's bones randomly.

Normally, the hydraulic/pneumatic soft actuators need to keep both opposing muscles in constant contraction, and thus, in constant stress. So if a soft actuator actuated metal arm bumps into you, they wouldn't just bend like organic arms, it would be like a solid metal bat striking you.
If only one side is actuated and the other relaxed, the impact would be less painful (I think).

Also, my idea would be to put one of those telescopic drive shafts with universal joints in the middle (inside the spring) connecting the upper plate with the lower plate through a universal joint that can rotate.
Like any of those that you can find online:

Note that the prices are in Real (brazilian currency), so it would be even cheaper in Dollar. Which is nice, since you will need to buy a lot of them. They will be used in almost every part of the body: shoulders, arms, torso, ankles etc.

However, these are for RC toy vehicles, not actual cars, so its strength would definitely not be able to hold 1 ton.

I also don't even know how I will make that weird lower torso joint shown in the humanoid torso above.

The size and materials required to be used in these shafts, joints and articulations need to be properly calculated later to check if they will be able to withstand 1-2 tons of force under then.

Also I know I could simply use a ball joint for everything, but I quite don't like ball joints (to be used on everything). It has a limited amount of movement, unless you add paths on the socket or you make the socket super large in order to allow un-constrained movement.

However, just like in the human body, this has a high risk for the joints to just escape the socket. A literal bone dislocation, just like it happens in the human body.

And to think that our shoulders are just being held in place by a few ligaments...

I hope these images aren't too graphic to be posted here, but it is only for educational purposes.

Well, looking at those things I think I can kinda build the skeleton with free available 3d models that you can find on the internet and modify them.

For example, this model I found on Thingiverse that is free to use. I can download it and simply throw it on Blender.
Or I can download this model I found on Grabcad that is also available for free and also throw it on Blender.

Now I will download a free and basic human model so I can position the materials in a somewhat humanoid way.

Like I said, there is a lot of tutorials on the internet about Blender, but basically, I'm just importing these objects, scaling them down, applying transformation (Ctrl+A [trust me, you need to do that after scaling objects, or else they will act weird later]) and organising them on the 3D space.

(The mesh is only showing its connecting lines [vertices] because I selected the view mode by pressing "Z", then selecting "Wireframe")

The box in which the human model is in has 2 meters of height, and I scaled the human model to 2 meters of height.

In Blender the Z axis is the vertical axis, so you can convert it to meters or other scales, like millimeters and so on. This model now has 2 meters of height.

I couldn't find the low parallel manipulator with 3 degrees of freedom, so I just copied and scaled down this 6DoF platform.

It is just a 3D sketch anyway, so don't worry too much about these details for now.

I also added the Stewart Platform to the shoulders.

I hope this is clear enough, but everything is just floating. The hardest part will be connecting everything somehow, and replacing the pistons with artificial muscles.

Now I'm scratching my head because I don't really know how to do the hip connection with the femur.

Yes, I showed a scientific paper on the subject, but the arms and legs are literal stick lines on their 3d model.

Screw it! Add more Stewarts!

Also, just note that the two "hip platforms" are a certain distance from the torso, I did this because it could be interesting for impact/shock dampening for the legs.

I just downloaded for free this spring 3D model and this universal joint shaft (that is also telescopic) and added to the model.

While doing this, I just noticed that the Shoulder Platforms where kinda "hitting" the top plates on the Upper Torso Platform, o I moved them a little bit  to be spaced between the triangle.

I also added a triangle plate between every platform, and also a some kind of "butt division" between the lower plate of the Lower Torso Platform and the Hip-Femur connections.

I think I should jus flip the arms connections instead of doing that.

Also, I just noticed that maybe flat plates wouldn't be that great for weight distribution and torsion (since the actual actuators will be pulling, not pushing), what maybe could be easier to make at home (or pay some welding shop to build it).

Obviously, I still don't know which would be the best dimensions and distances between these plates, so maybe they are too far away from each other, and maybe I will need so many multifilament actuators that I will be forced to increase its size.

Just added a neck platform between the shoulder platforms. My god, I'm adding Stewart Platforms everywhere. Am I addicted to this? :(

Well, I've made a terrible mistake: since my intention was to just replace the Stewart Platform 3D model later with artificial muscles and so on, I didn't pay much attention to it.
So it seems that the 3D model was so heavy that adding to many of those in a single archive was just too much for my PC to handle; Blender crashed and I lost the file, lol.

Anyway, I found a scientific paper that used the 3dof parallel manipulator as the thighs, but I think it would also make sense if these where just long Stewart Platforms, because your thighs can also rotate in its axis.

The paper is "Kinematic Modelling and Motion Analysis of a Humanoid Torso Mechanism".

Also, it is relevant to keep the femur/legs as close to the body as possible, normally it is not a problem for humans, since we don't have a lot of mass, but it is very relevant for robots and mechs.

There is this website (that I love and I always have trouble finding) that really really really discuss all the ins and outs of almost everything in sci-fi, but since they write a lot, let's just say that the center of mass of the mech needs to be aligned with the surface area of the mech.

I don't know how much the center of gravity and surface area my mech will need (or "mini-mecha" accordingly to this website).

I erased the text that made me search for this, but it is theorised that the femur is angled exactly to allow the feed to be as close to the center of mass as possible.

"The bicondylar angle (or “carrying angle”) evident in the distal femur of humans and
fossil hominins has been suggested to increase the efficiency of bipedal walking by placing the
foot closer to midline"

Source: "Development of the Femoral Bicondylar Angle in Hominid Bipedalism" (I couldn't find the complete research, lol)

Source: "Development of the Femoral Bicondylar Angle in Hominid Bipedalism" (I didn't read it to the end, there is probably useful information, lolololol).

Also, that's the reason bigger robots need to make a big and akward lean to its sides when walking.

Or need to make the "model walking" (or "catwalking"), like this tiny robot:

Well, humans kinda do that too, but it is kinda hard for us to notice because, well, we are literally walking and looking at other people walk every single day of our lives.
But you can notice it if you walk really slowly.

Anyway, back to modelling:

Of course, I'm not as unsettled as people would normally get when their entire progress is lost because I actually did almost nothing.

I just added free models that I could find on the internet and just clumped them together in some kind of construct.

But this time I will try to actually 3D model everything, because I do want to let the model also available for free, and I don't want to get in trouble for releasing other people 3D models without their permission. So, here we go.

Starting again I've made a cube and imported the other models I already linked in this post, I imported the stewart platform that had too many faces and just let the triangular platform on it because I want to use it as a base for a new triangular platform with cylinders.

First I've made this sketchy looking spring following this tutorial, you can make it look less like it came from a PS1 game by messing with the settings, but I don't want to risk crashing the archive again.

I will just align all the meshes/shapes/objects at the side of the final object because it is easier to build something that uses the same parts again and again, after all, this has 10 stewart platforms (including the ankles and wrists) in total, so...

Just imagine that sketchy balloon in the middle to be the representation of the multifilament bundles of artificial muscles and the sketchy looking tubes to be the stewart platform structure, lol.

Finished the torso, now time to figure out how to make a femur, and yes, I just used a plain tube in the middle of the springs instead of modelling a telescopic shaft with universal joints. I'm not a 3D modeller ok? :(

And yes, I'm still using the human model as a basis for the torso, the robotic skeleton is more or less aligned with it.

However, the shoulders are too much in the front compared to the human model, maybe I should mirror it to the back...

It does look weird, but it still is a really elongated stewart platform on each femur to each knee. This will be necessary to allow as much muscles to be packed in the lower body as possible, which these need to be really strong, since the lower half of the human body can lift 3 times the weight of the body.

And now that I'm making this 3D model, I'm starting to think that this cannot realistically lift 1 to 2 tons of weight. :(
Imagine this sketchy clump of tubes and homemade artificial muscles being strong enough to lift 3 to 6 tons...

And this 3D model still doesn't have the energy source, the pilot and the encoders required to tell the computer where each limb and muscles are...

I didn't knew what I was expecting for the feet, but it sure wasn't this, lololol.

Notice that I didn't add any kind of joint between the limbs, I'm just assuming that future me will be able to do that.

"Finished" 3D model of the mech body, the stewart platform on the forearms are meant to move the wrists. I didn't made hands because I'm not really good at 3D modelling.

I mean, I could do the hands, if it took me a week or so, lol.

Initially I was intending on make this Project Log to be both the 3d model sketch showcase and an attempt of sourcing the materials required to built it, but this project log is already too long and I'm already too tired.

And I almost forgot: here is the 3D model free to download on GrabCad (if you even want to download such crappy 3D model).

Friday, 13:06, 02/12/2022 - I'm super procrastinating.

In this mess of thoughts and cool robots that I call "my mind", I did had some simple objectives that I already put some thought into it. Like this project being easy and cheap enough to build at home, unlike the carbon nanotube artificial muscles that need acetylene (a volatile, flammable and explosive gas) in a fricking furnace in order to be synthesised.

But let's lay everything in a plain and simple way:

1. The skeleton, the actuators, the system and the power supply need to be simple and cheap enough in order to be bought locally or made at home.
2. The full mech needs to be able to lift at least 1000 Kg of weight either on the hands or in the shoulders. This does not include its own weight and the weight of pilot, which can shift the weight demand to higher numbers. So let's keep with 1,5 to 2 tons in total.
3. It is only possible to calculate the amount of muscles needed if there is a skeleton designed to support all this weight.
4. After designing the skeleton, it will be time to design the actuators.
5. And by measuring the amount of energy that it requires to lift a certain amount of weight, just then it will be possible to design the power supply.
6. If the power supply can't power the entire body in a practical way, then it will be useless.
7. If all the previous steps are done without trouble, it will be required to research and add the sensors to the design in order to be able to control it.
8. After everything is designed, then it is time to build.

Although the best course of action is to continuously prototype and go back to the drawing board in order to continuously address the problems faced during the building process, I'm too broke to actually do that.

So I can only hope to do it in a single well planned shot in the sky that may or may not work.

Tuesday 16:06, 29/11/2022 - I'm still procrastinating...

So, I was reading and re-reading a lot of scientific articles I had on my PC (I have gigabytes of scientific articles about a myriad of subjects, mostly focused on artificial muscles), and I remembered some interesting things I saw.

Method 1: No moving parts active valve with variable viscosity liquid (AVVVL).

That's quite a mouthful, but let me explain:

There is a type of variable suspension/shock absorber that uses a liquid that can have its viscosity changed by passing an electromagnetic field through it.

So you can progressively and instantaneously change the flow of the fluid without the need of expensive and complex gradual valves.

In the video the guy simply use a metal powder mixed on some liquid and then moves a permanent magnet on it, with that, the liquid achieves such amount of viscosity that no liquid is capable of escaping the syringe.

(Video is automatically on the time mark I'm talking about: 4:59)

So, with this simple trick even MYSELF can make a simple solenoid valve system with no moving parts that works instantaneously at home using of-the-shelf parts online or on my local stores.

How cool is that?! :D

One could use those cheap electromagnets or homemade coils (and electromagnets) around the tubes as solenoid, and they are so small you could put on every single muscle instead of relying on those heavy solenoid valves that can overheat over time.

The few problems I can think of are figuring out the amount of pressure these electromagnetic valves would be able to hold, and also that these would need to be constantly active to avoid every muscle to be instantly filled; not to mention the risk of increasing the temperature on the ferromagnetic particles within the liquid.

But even then, you could have four or five solenoid valves (ugh, I know, solenoid valves imma right?) that are normally closed that would direc fluidt to each limb, so the electromagnetic ones would only need to be active once the power is directed to them.

But of course, it is not a perfect solution or anything like that, you still have the problem of the "solenoid creep", after all, you will need 2 or 3 of those for every muscle. 

The only difference is that you don't need a huge backpack full of solenoid valves, and you could use electromagnetic coils that are way smaller than the microsolenoid valves you can find; Valves that may or may not be able to withstand the pressures you're dealing with.

Method 2: No moving parts hydraulic pump.

I remembered I once saw a hydraulic pump with no moving parts, and I found it.

The fun part of it is that it completely destroys the solenoid valve "tyranny", you can literally put a valve in the muscle itself, you don't need an active valve because the pump on itself is the valve and the pump.

In this website and in this paper a malleable pump with no moving parts is shown powering some soft actuators (aka artificial muscles), they use more or less the same principle used in the dielectric elastomers:
Thousands of volts with a minuscule amount of amps, so it is super safe, because Volts times amperes is equal to wattage (this uses less energy than a cellphone).

A quote from the paper itself:

The relatively high voltage required to drive the EHD soft pumps (5–8 kV) might raise concerns about safety and size of the power supply. These concerns have been addressed in a previous work on Stretchable Pumps where the authors demonstrate untethered operation using a palm sized battery-driven power supply weighting 18 g. Each of these portable power supplies is limited to a current output of 100 μA, widely below the human safety threshold (1–10 mA) but large enough to power up to 6 Stretchable Pumps at the same time. Nonetheless, some applications would benefit from reducing the driving voltage. Strategies to reduce the voltage include reducing the electrodes spacing and searching for combinations of electrodes and liquid materials showing higher EHD performance at lower fields.

Accordingly to a google converter, 100 micro amperes is equal to 0.0001 amps (or "1e-4"). So, 8kV times 0.0001 amps is 0.8 watts.

The problem is that as shown in the supplementary video in the paper itself, it is accelerated by 8 times. And since the video takes more or less 3 seconds to fill the single filament muscle, I can assume it takes 24 seconds to fill a single "fiber".

I wonder how you could increase the speed of actuation, maybe multiplying the amount of pumps? Increasing the voltage?

The pump seems to be extremely simple to make, but I still can't figure out how to actually make one. The biggest limitation is always that I'm not an engineer and I don't have the money to pay an engineer to design these types of things.

The muscle is the same one from that paper about multifilament artificial muscle, by the way.

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Method 3: piezoelectric pump.

There are micropumps or pumps that have no moving parts that use piezoelectric buzzers to move elastic membranes in a system, maybe there are commercially available ones, but this means they can be really cheap and easy to make, maybe you could have one for every muscle.

And the interesting part is that these could also be used to pump air (I hope), because there are piezoelectric air pump for aquariums.

So? What y'all think?

Tuesday 10:53, 29/11/2022 - I'm still procrastinating

Another thing that a lot of people (including me) don't think much about humanoid mechs is how the squishy hummies control them.

your first thought is maybe control them just like you would control in a video-game: use joystick to look around, use the other joystick (or arrows) to move around and other buttons to make other actions, such as jump, open doors etc.

The problem is that these actions work on videogames because you don't have to take irregularities on the floor elevation, speed, balance control, force applied to each limb and a myriad of different things.

Inside a game you're a floating camera and the animations you see are just visual facades to trick you into thinking you're actually opening a door, kicking a wall and so on.

In order to make a robot to move around by its own with simple controls such as arrow keys (or A, W, S, D keys respectively), you would need to fit it with some kind of sensor to calculate depth and detect the position of the body in real time, and other types of sensors to provide other types of requirements.

One method is through the use of LIDARs (a RADAR that uses laser instead of radio waves) and encoders.

Self-driving cars use these and these sensors are really, really, really expensive, and even more expensive to be processed in real time.

Yes, maybe you could use cheaper alternatives, like using a bunch of cheap laser rangefinder/telemeters online and give the task of a computer to figure out how to read all that information in a useful way so they can somehow figure out how to walk.

Anyway, all of this just to say that is really, really complicated to make these a*holes to walk.

Or maybe not, these guy were able to do it with a cheap arduino and gyroscopic sensors (I think).

And don't even get me started on mind controlling electronic stuff.

Yes, there are sensors that can read the signals in some parts of your brain, but these signals are super mega simple and can make only simple tasks, like turn on or off something.

And there is also muscular sensors that can detect the contraction of your muscles and give it orders to robot prosthetics, but I doubt it is possible to make complex motions.

In these really cool videos it is shown more or less how to make one of these sensors do work, but even then, you can see that some times the guy lifts his entire arm and the sensor doesn't activate.

I thought on an alternative and it will kinda make a crossover with another project of mine that I'm definitely not procrastinating and avoiding doing it.

It is a full body VR haptic suit, the idea is to use cheap piezoelectric buzzers that you can buy online to make a VR suit that allows you to feel and move in the virtual world.

Piezoelectric buffers are really useful and versatile, you can use them as either as a sensor, a vibration feedback and even as a electric generator.

Well, in my empty head of mine, it seems something quite feasible to do, I just don't know anything about programming and other stuff.

However, if one can make a virtual avatar to move in a virtual world with this haptic suit, maybe you could control a human sized mech.

And that would also kinda cheapen up a little the controls and "brains" of the mechsuit, afterall, you will be the one controlling the body, the computer won't need to figure out how to walk, recognise floor elevation and all that stuff simply because you will be doing all of that.

And humans kinda "train" their entire lives to walk, tactile sense and manipulate things.

But well... I don't see any piezoelectric VR suits, do you? It is probably a stupid idea, who knows...

Also, just to refresh your minds, let's remember the megabots giant robot duel that happened a couple of years ago, and oh boi...

I know they put all the effort in the world just to make their dreams real, they definitely are way better professionals than me and would be able to outsmart anything that I can come up with...

... But...

... Trying to control a humanoid mech with buttons and joysticks is really awkward and hard, not the best joice, I would say.