FulanoDetailI know I just said that the Project Log 90: "Final" Project Log. would be the last project log, but something is itching me to post its contents here.
It is not like I'm gonna finish it anyway, that's all completely out of my scope of knowledge and skill.
And it is not like anyone would care, anyway. Nobody reads these damn things.
If you want to read the google document (slightly more organized): https://docs.google.com/document/d/1FmS4rI9PNGLeOLccWW2pbyl1sPEWZbrq-mOIGy_beRc/edit?usp=sharing
"Project Log 90: Final Project Log.
Sunday, 08/09/2024, 07:59
To remember:
I AM NOT AN ENGINEER AND ANYTHING THAT YOU DO, YOU DO AT YOUR OWN RISK. YOU CAN DIE.
YOU HAVE BEEN WARNED.
In fact, I’m confident that nothing in this entire project will actually work.
Before you read it:
If you want the 3D models of everything, just check the “Files” section in the hackaday project’s page, I will add them there.
If you want to know my thought process around everything, keep reading.
If you just want to know what everything does instead of going through walls of text, go to Project Log 90 for summarization.
Or this link (I still didn’t finish writing it)
DIY Mech/Exoskeleton suit: Project Log 90 - Project Completed. The idea was to only write this once I completed this project log you’re reading, but… I write this document with my trail of thoughts, not necessarily as a proper document.
Also, in the recent Blender archives you will see pastes/collections inside the program named “Steps”. They are not step-by-step tutorials.
Before every significant step of the 3D modeling process of the objects, I make a copy of the meshes. So if something goes wrong, I don’t have to redo everything from scratch.
But before you read it²:
I designed the mech to lift around 1000 kilograms (2200 pounds) at the same speed of a human body, so it will be highly complex and difficult. This is essentially throwing a whole CAR at the same speed and easiness that a human throws a basketball.
However, you can simply build it with safer/cheaper materials to achieve a lower force output.
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I had poor months on productivity and focus for this project. I wanted to finish this project log and the project this month, since it will be the 2 year anniversary of the project on 24/11/2024. But here I am, day 04/03/2025 while walking in circles.
This whole thing reads as the ramblings of a mad-man, and it is as frustrating to read as it was to write it down.
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But anyway, I just saw these videos and I think it was really interesting:
A rant on personal engineering projects
THE DESTRUCTION OF MECHA (this guy thought of everything that I thought, I wonder if he would be interested in this project)
REBIRTH OF MECHA 1/9: PATLABOR & BUILDING ON REALITY
Making REAL Fallout Power Armor (Part 1/6)
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Like I said before, I had to divide Project Log 87 in 3 different project logs because I wrote too much.
Sorry for that.
I 3D modeled, but I didn’t 3D model every single thing about the mech and jumped to the conclusion that I “just” needed to build it.
That was incorrect.
Now, in this Project log, I will actually 3D model every single thing about the mech. Including molds, extruders, circuit boards, the program for the actuators, screws, bearings etc.
I mean, if I can do something without the 3D model, then I won't do the 3D model.
I need to make molds for every part of the brushless motor, then I need to make the bearings, casings, the cooling system and the molds to make everything mentioned here.
But let’s not get ahead of ourselves, one thing at a time.
Let’s start from the start.
Recapitulating:
For some reason I feel the necessity of laying down all the information about this electric motor. I mean, all the information is all stretched out throughout the project logs because I’m an unorganized idiot…
OR am I always talking useless crap because I’m subconsciously trying to inflate the project logs in order to feel like I did more than I actually did …?
- 99 slots, 66 poles, 30cm of diameter, 24cm of thickness more or less. 5 kilograms worth of aluminum coil per motor with 20 wires with 1mm thickness (and yes, this is taking into consideration that it has proper AWG for 500 amps instead of 1000 amps and 1.7x times more weight in order to compensate for its resistivity at room temperature), 35 of these resulting in 175 kilograms of aluminum metal in total. Probably it will reach 200kg to 300kg with the permanent ferrite magnets and the soft ferrite cores.
- I re-checked the height of the 24 turns of coil with the 23 wires with 1mm of thickness, and due to 3D modeling fuckery, the coil was telling it was 3 times bigger than it actually was. The actual size of the 24 turns with 23 wires with 1mm of thickness is actually 240mm of height, or in this case, thickness.
- And its actual weight is 5.8 kilograms. and its actual magnetic flux density is 0.06 teslas with an air core.
- If you add a ferrite core or a metal core, it can even reach 1 tesla of magnetic density flux (the solenoid calculator says that it would reach 7 Teslas using a ferrite core with 20mm of diameter and permeability of 125), but I don’t know if it would be saturated.
Just like I said on previous project logs, you can change the diameter and thickness of the motor in any way you want and it will work just the same. And the configuration can also easily change from Axial to Radial. More or less, the bigger the diameter of the motor, the more torque it can output, but the harder it will be to fit into the mech. I’m simply settling with these dimensions(30cm by 24cm) because it is the most compact shape.
- By the way, each motor is meant to output 300 kilowatts maximum, but normally you would only need 100 kilowatts. This means that you can carry 3 times more weight than its rated weight carry (which is 1000kg). However, brushless motors are less efficient when working below its rated output. So you can cut ⅓ of the total weight of the motors. If you decide to make a motor with multiple stators and rotors, you could turn-off the current from passing through the wires before feeding into the motor.
As such, if you cut ⅓ of the total weight for the 100 kilowatt output and more ½ of the weight in order to work with the -70ºC cooling system, you can reduce the total weight of the actuators to below 50kg. However, I won’t be doing that. Working with -70ºC cryogenic fluids is dangerous, and I already have enough hazards with this project. The risk of dying of electrocution and being burned alive with the acidic molten carbonate fuel cells are already enough hazards for me (assuming the mech won’t crush me to death accidentally or the charcoal fuel won’t explode).
- Since the mech is fully electric and direct drive, you won’t need to make it rotate 360º degrees, and as such, you could replace the permanent magnets of the rotor with electromagnets with soft cores. I would need to figure out the amount of turns for a certain amount of teslas, but you would also need to increase the input power unlike the permanent magnet type. The only reason I’m willing to take the extra energy cost is because I’m not very confident I will be able to find ferrite soft core powder and ferrite hard core powder on the cheap. We are talking about around 100kg (more or less) of this stuff.
Like I said, the calculation of the coils was an approximation and I will probably need to do a few dozen tests in order to figure out how the coils will actually wind around the slots. The same thing for the soft ferrite core in which the coils will be wrapped around.
- 99 slots x 4 stators per motor x 35 motors in total = 13,860 coils in total.
- 66 poles x 5 rotors per motor x 35 in total = 11,550 magnets in total.
- OhLord.png
- I think It will be a good Idea to only use the 300 kw motor at the legs and the 100 to 200 kw motor in the rest of the body. Maybe It Will be a good Idea to use multiple rotors and stators to allow modularity within the mech.
- On the subject of reducing weight and size even further, I also just had an idea which I’m not very sure if I will follow or not. Essentially, the idea would be to cut the stator in half, flip it and make it work like a rotor. If you have two stators on opposite sides, generating opposite magnetic fields, then they would rotate (if they can rotate). That could be a way of cutting down its size and bulk. There are induction motors that work like that, called “double-wound” or “doubly-fed” motors. I will buy a small BLDC drone motor and ESC to test it.
I did have the idea of following up with the concept of parallel mechanisms for the limbs, but after sketching a few ideas on my drawing table, it really wouldn’t work out in this case. Every single motor would need to be positioned in parallel (thus the name, duh) based on the number of degrees of freedom on the mechanism.
So, Thighs have 3DoF, Knee is 1DoF and ankle has 3DoF, so you would have to align 7 motors for the total 7DoF. Unfortunately, I can’t find more than 4DoF parallel mechanisms for reference.
Concept: 4DoF Spherical Parallel Mechanism based Robotic Leg
2022 Biped robot with 4-DoF spherical parallel link mechanism
This idea ended up just like the Stewart Platform idea: it seems interesting as heck to make all the actuators on the leg add to the output, but it ends up too bulky and limited.
Even if you don’t use parallel mechanisms, I still don’t know how you could make a 7DoF and 9DoF (the latter, for the 2 extra actuators for the shoulders) where all the actuators' inputs are added to the mechanism force output.
BUT I can try something similar, like this one:
Design of a Serial-Parallel Hybrid Leg for a Humanoid Robot
I’m sketching and I was able to make 9 DoF with only 6 actuators.
… But I don’t know how to properly explain in a succinct and direct way how each part/linkage/actuator works on the movement.
Here we go:
I sketched this abomination, so I hope it is clear enough for y’all to understand (it isn’t).
There are 6 actuators in total (the 6 disks on the left) for 9 degrees of freedom, which 4 of them transmit their rotation through a foldable rotary bar transmission in the middle, ending in 4 rotary disks that move 4 linkages, 2 thigh linkages and 2 knee linkages. The other 2 exterior actuators are directly connected to the thigh and knee linkages.
If the thigh linkages rotate against the knee linkages, then only a motion on the knees will be done.
If the thigh linkages rotate with the knee linkages, then the whole thing will rotate.
If left side thigh and knee linkages are rotated against the right side knee and thigh linkages, then the feet will rotate in the y axis (on an imaginary line on its middle).
The 2 exterior linkages are misaligned with the thigh and knee linkages with a longer bar, if they rotate against or far from each other and the other 4 actuators are still, then the whole leg will rotate sideways.
If one of the exterior linkages and the whole leg is standing still while the other exterior linkage is actuating against or far from the other exterior linkage, then the feet will rotate vertically, like when you are tip-toeing.
If both exterior linkages rotate together in the same rotary direction (clockwise or anti-clockwise) while the rest of the linkages are still, then the 4 rotary disks will go up, down or rotate on their own y axis depending on how they synchronize their rotation.
(Actually, after thinking a little bit about it the two exterior links wouldn’t work properly in this configuration, they shouldn’t be connected to the feet and actually connected on opposite sides, one connected to the thigh and another connected to the knee. Probably needing an extra exterior link for the up and down motion of the base. The feet could be controlled by the other 4 actuators without the exterior linkages by attaching them to the feet in a diagonal)
Well, NOW that I actually have done something, I came to the conclusion that I don’t like this idea.
Essentially, the linkage system is too complex, it would be too bulky, I don’t know if it would be heavy, but it would definitely be really complex to program.
Remember, I’m doing this thing alone. From scratch.
Every bar, every joint, every bearing, every screw. Everything will be built from scrap by myself.
For competent professional engineers this project would be a walk in the park, for me… Well, the google document where I copy-pasted all the project logs has 1300 pages.
The conventional way of attaching the electric motors will be easier to build from scratch, since I will essentially make every motor and joint the same way. It will be like building a giant Lego part.
Building an Robotic Arm EASY with Modular Components!
This is an example on how I intend to build it.
BUT, I think it would actually be possible to do something similar to a linkage part on the ankle/feet.
The idea would be to use it as a virtual shock absorber/spring with the electric motors to avoid damage to them.
Example:
Virtual spring constants on the prototype leg
However, I have another little problem with it: the motors close to the output should be smaller and weaker.
Example:
BCN3D MOVEO - A fully OpenSource 3D printed Robot Arm
Like I said throughout all these project logs, although this is the best idea/mechanism to use, it may be not practical to do in a DIY way.
I would need to make every single motor different than the previous one, which is a pain in the butt.
… God, how disappointing it is to throw away all these cool ideas just because I’m incompetent at engineering… 🥲
(I do think that this section is useless and should be deleted, but heh, maybe it will help someone)
- The rheostats/potentiometers/electromechanical switches for the 3 phases should be electromagnets attached and insulated on two wide thin plate-wires. (that is just a Relay switch, but I won’t be buying them because of cost, too expensive per unit to use on 35 motors [reed relays can achieve kilohertz btw]) In order to switch the wave, its frequency and intensity, all the system must do is select how many of the electromagnets will attract each other and complete the circuit. The faster the pulses, the faster the electromagnets will connect and disconnect the wires, the less electromagnets connect, less current will pass because the resistance will increase. The non-conducted current will either be transformed into heat or go somewhere else with less resistance. I'm still trying to decide how I can store and release this extra current. Conventional batteries and capacitors won’t suffice, they aren’t energy dense enough for this. I don’t like this system either, but I don’t have the money nor the expertise to make 35 Electronic Speed/Position Controllers for 35 motors with a maximum 300,000 watts of input.
Maybe diverting the extra energy to the electromagnets in the rotors/electromagnetic-bearings could be a way to circumvent that?
Although I personally don’t really like to waste energy…
- By the way, I couldn’t add this information on the previous project logs because of the limit of characters per post, but according to the TrainedGPT, the RPM of this motor would be in fact around 100 rpm at a frequency of 80 Hertz and 600 volts. Increasing the frequency would increase the rpm, but decrease the torque. Which I thought was interesting. … But I don’t know if this is about brushless motors or induction motors, since ChatGPT didn’t know how to tell the difference.
Speaking of that, it would also be possible to use a system with regenerative braking in order to recycle some of the eddy currents generated by the high frequency. And/or add an inductor coil in order to do that. Maybe that could also be used for temporary energy storage?
- Now, for proper control, what I can do is take cheaper ESC’s/Circuit boards for smaller brushless motors and translate its signals to the beefier brushless motors I’m using. Controlling the mech on the cheap. I will need to make the sensors for the current/voltage/position myself or buy online. I think this one video here may be useful for that: How to use a multimeter like a pro - Clamp meter
- Finally, I said I would anodize the aluminum wire. But it was because I believed the method would be simple and fast, after searching a little more, it seems that the method is not as straightforward as I thought. Maybe just using conventional insulating enamel will suffice.
- Again, all of that is assuming that in fact, the 99 slot 66 pole direct drive brushless torque motor will work just fine with 0.06 to 7 teslas of magnetic flux density at its air gap. I could be soundly wrong, I could be right. I will only find out when I finally build it. … Or if some kind soul that understands the subject better than me helps me out.
This website said it would have 28,000 newtons of electromagnetic force, every website/calculator that I use gives a different answer. I’m not even confident with the Limited Element Simulation, not because I’m not confident in the program, but because I’m not confident I will use the program properly. I tried it before and the results were useless at best. By the way, I asked ChatGPT and even giving conventional numbers they either caculate 0.0000000001 nm of torque or 10000000000 nm of torque. So, yeah, thanks ChatGPT. What could I do without your useless help?
I asked on Stack Exchange Electrical Engineering, but I bet they’re going to insta-ban the post. They do tend to delete posts that are too stupid to be answered. Well, they didn’t delete it, but nobody is answering. Super.
- One thing I noticed tho: Assuming that instead of using 23 wires with 1mm and 500 amps, you instead use a single 1mm wire with 576 turns and 20 amps, you would get the same amount of teslas (0.06 and 1 to 7 teslas with core). Of course, this isn’t counting voltage, but I would assume that this coil would use around 24 volts, which is a common value for electronics. 20 amps x 24 volts = 480 watts. As such, I would assume that this could be a good indication that this motor would really poorly perform. I don’t really know the answer, as always. But maybe using the “trick” of separating the wiring in parallel, you could increase its power? For example, when you divide a wire in half, the voltage stays the same, but the amperage is equally divided between the parts. So, assuming that you do it before you feed the motor, and that only ⅔ of the 99 windings are active: 20 amps x 66 slots active = 1320 amps × 24 volts = 31,680 watts. You can still increase the voltage: 1320 amps x 600 volts = 792,000 watts. This is only ⅔ of the wirings, so I would decrease the wiring by ⅔, which would result in 264,000 watts and as a bonus, would make the motor 3 times lighter. In the case of copper, it would reduce to 6.3kg instead of 19 kilograms, and in the case of aluminum at room temperature, 3kg instead of 6.
- … Wouldn’t that make this motor have a power density of 100 kilowatts per kilogram? 100 thousand watts, for every kilogram. That is denser than motors using superconducting coils. If it was that easy, someone would’ve built it, right?
- And unfortunately, I was correct, I miscalculated the size of the wire to be only 23 wires with 1mm of diameter when in fact it should have been at least 10 times that value. So 60 kilograms for aluminum and 190 kilograms for copper.
- Using the correct current for the 440 amps 600 volts paralleled wound motor: 440/66 = 6.66666666667 amps for the wire with around 570 turns. The correct AWG would be 22, with cross sectional 0.327mm² and wire thickness to be 0.64516mm.
- If you assume the total current of each phase to be the input amperage: 440 amps/33 = 13.3333333333 amps for every wire. AWG 19, 0.91186mm of thickness and 0.653mm² of area.
- I confused myself a little bit, but if I read the waveform of a 3 phase brushless motor correctly. Then when one wave is at its peak, the second wave is at more or less half of it and the third phase is at zero before reversing. So 1 + 0.5 + 0 of the total power input. So at that specific point, the amperage is divided by 1.5 between the motors.
- Since there is one phase and half of a phase: 33 + 16.5 = 49.5 slots (I know that the slots in the second phase aren’t individually powered and in fact the power would be divided equally between all of the slot’s windings, but this value is only relevant for the first phase). 440 amps / 49.5 = 8.88888888889 amps.
- And thus, it is the AWG 21 with diameter of 0.7239mm and cross sectional of 0.412 mm².
- Then you need to increase it by 40% for aluminum in room temperature, which will get you back to AWG 19 (0.91186mm of thickness and 0.653mm² of area). lol
- By the way, the AWG 19 with 1mm of thickness is already a little above the rated amperage, so this can easily go with 10 amps or even more. Like I said before, some charts say that it can withstand around 15 amps at 90ºC, others that it can only withstand around 1.5 amps.
- Which is pretty similar to the initial result where I used 1mm and 576 turns weighing 6 kilograms. Which is still 50,000 watts per kilogram. Which² made me weirded out, but in fact is just the coils, not the cores and structure, so the power density will be reduced even further to something similar to evolito’s motors.
- The new magnetic flux density according to the solenoid calculator is either 0.01 teslas or 1.3 teslas using a ferrite core with permeability of 125 at 1mm of distance from the surface. At its center it would be 3 times as strong, which I don’t really understand, isn’t the ferrite core meant to direct the magnetic field to the surface?
- Well, I guess it was worth “recapitaling” this time…
- … Or not, because it ended the same way, but with a slight correction. 😐
- According to the same calculator, if you used 50 wires with 1mm (0.653mm² of area) and 12 turns, it would have the same result.
- What a waste of time… ugh 😣
- According to this answer on Stack Exchange, the parallel winding of slots in a phase makes worse motors than winding it in series (like it is normally done).
- … So not a waste of time after all… I guess…?
With that said… What should I name this motor tho?
Maybe “Xangô-99”?
Xangô (or Shango in english) is a deity of Afro-brazilian religious roots called “Candomblé”, he is one of the various “Guardians” (like angels) called Orixás (Orishas in english), lord of Fire and Thunder and the Forgesmith King of Justice.
I’ve talked about this before on some of the countless project logs ago, but here we go.
IF the laser thruster works, I would call it “Guaraci 1”. Guaraci is the sun god in the pantheon of the Brazilian indigenous people of the Tupi-Guarani community, since I’m essentially flying with the power of the sun, I think it is fitting.
Sometimes understood as “the one who gives life” and creator of all living beings, just as the Sun is important for nature.
The etymology of the word comes from the combination of the terms kó, 'ara and sy, which, together, mean "origin of this day".
Now I’m indecisive about the name of the mechanoid itself.
Like I said, I thought first of “Mapinguari” (it is like a Brazilian indigenous Yeti), I also thought of “Ogum” (Orisha of technology, courage and hard work), although both names are great, Xangô has an african root, Guaraci has an indigenous root, what should be a third root to name this mech?
I think I will go with “Zumbi dos Palmares”.
This is a gross summary, but Zumbi was a big leader from freed slaves during colonial Brazil called “Quilombos” (the ones responsible for creating the Afro-brazilian martial art called “Capoeira”). Unfortunately, he was killed with his resistance and information about him is scarce.
Myths about him appeared however, saying that he raised himself from the dead and still kept fighting for the freedom of his people (at least that is what I was told when I was a kid).
And through this mech, Zumbi lives again.
(that is quite the pretentious affirmation since I don’t know if this mech will actually work lol)
It would be really cool to see a capoeira-fighting-zombie in some fighting games, tho...
Out of curiosity - Graphene resistivity:
WebSearchGPT linked an article saying that Graphene has the same conductivity as copper at room temperature (or even 60% more conductive) while having a similar density to aluminum, but I don't know how you could make graphene with this specific resistivity.
I don’t even know how you could make a continuous graphene fiber to build motors with it.
What's the deal with axial flux motors?
On the subject of DIY system/circuit boards:
First, I found this website where you can find, create or edit circuit board diagrams and see how every part works. The link leads you to a 12 bridge rectifier, an AC to DC converter that is intended to get rid of the pulsations inherent to this type of converter.
Like I said in previous project logs, I was thinking of buying electronic components that I can’t make myself, such as one-way diodes.
The only diode types that I could make would be Vacuum Tubes, they are literally just a light bulb. The difference is that their way of working uses specific materials that release electrons when heated.
They are said to be 97% efficient. But I bet this information is incorrect, since thermionic generators only have 20% of efficiency, and since this is a thermionic machine…
In any manner, I was wondering how I could make a rectifier diode in an electromechanical way, and I came across this video (I used the option to translate to english).
Essentially, it is a relay with a permanent magnet on it, when the current is going in the way you want it, the coil will attract itself to the magnet, touching the electrode. When the current reverses, the polarity in the coil will reverse and separate from the magnet/electrode.
You would need a second one (or four more) to convert the alternating current completely into direct current.
The problem is that it wouldn’t happen at the same speed as the current travels (basically the speed of light), so a little bit of current would bleed in reverse.
And in the video, when you compare the energy output of both diodes, the electromechanical diode seems to amplify the current or voltage (I can’t read the voltmeters) for some reason. And when I say “amplify” it is not adding energy to the current, but increasing either the voltage or amperage while lowering the other.
There are also these other videos about DIY diodes using metal oxides:
- Homemade Diode
- Make Razor Blade Diode for Crystal Radio/Foxhole Radio
- https://youtu.be/PiPi8ZhA_Zs
- (#0062) Selenium & Copper Oxide Rectifiers - Different Types & I-V Curves
- Copper Oxide Rectifier
All this subject on Diodes and Rectifiers was due to the fact that I was afraid that the Molten Carbonate Fuel Cell that works at least at 650ºC would just melt any kind of electronics.
… But it never passed through my empty head that I could simply use a conductive material with low thermal conductivity, such as graphite and sodium silicate composite.
Then I could pass the current through a conventional electronic system to power all the things that are required.
Also, ChatGPT suggested these simpler computers to DIY:
“Modern processors are indeed marvels of engineering, with transistor counts reaching impressive numbers. For instance, Apple's M2 Ultra SoC, introduced in 2023, contains approximately 134 billion transistors.
Due to the immense complexity and proprietary nature of these designs, detailed schematics of contemporary processors are typically not publicly available. However, for educational purposes, there are several resources that provide insights into simpler processor architectures:
Intel 4004 Microprocessor: As Intel's first microprocessor, the 4004 is relatively straightforward by today's standards. Complete artwork, schematics, and simulators for the Intel MCS-4 (4004 family) microprocessor chipset are available, offering a historical perspective on processor design.
Complete Artwork, Schematics, and Simulator for Intel MCS-4 (4004 family)
Ben Eater's 8-bit Computer: Ben Eater provides comprehensive schematics and tutorials for building an 8-bit computer from scratch. This resource is excellent for understanding fundamental computer architecture and operation.
Simple CPU v1: This project presents a very simple machine made from registers, multiplexers, and an adder. The operation of this machine and its components is explained from the ground up, making it suitable for educational purposes.
Maybe I could make DIY computers with these for controlling certain parts of the mech.
On the subject of programming:
Well, I know absolutely nothing about programming as well, but after hearing that Factorio is a good tool to teach about designing circuits and programming, I got interested in games where you can actually program functional programs that you can use.
ChatGPT gave me a list, but I still need to check each game in order to see if I can actually program something like an ESC or similar.
PROGRAMMING CIRCUITS - Shenzhen I/O: Ep. #1 - Gameplay & Walkthrough
TIS-100 - The Assembly Language Puzzle Game That Nobody Asked For
[Trailer 2017] Screeps - MMO sandbox strategy game for programmers
Well, I checked it and the answer is a sad no. None of these games can be used to make something more advanced like an Arduino program for controlling brushless motors.
In fact, all the three games downscale the programming quite substantially in order to keep it simple and entertaining.
oh well…
Arduino on Wokwi - Online ESP32, STM32, Arduino Simulator
Animating Animatronics with Blender - Servo Animation Add-on
MarIOnette: Control Robots Inside Blender
real-time robot servo control using blender python
Arduino Visual Programming, with XOD.io
XOD visual programming (Arduino based). Tutorial: #1
03# Arduino Visual Programming | Control the Servo Motors with Potentiometers | XOD
Blender Arduino Servo Real time control Project Update 3
https://www.youtube.com/shorts/lkxXGh82lTU
Python Flow-Based Visual Programming Editor
CoffeeFlow - C# visual flowchart tool
On the subject of Fasteners and Bearings:
On another note, on the previous project log I suggested using holding electromagnets in the place of screws, bolts and nuts because it would be easier to fabricate, replace and fix.
Even though I gave up on the idea because it needs active energy input, I’m still intrigued by the possibility of using screwless/threadless fasteners.
These would be (supposedly) simpler to make, to use, faster to install and uninstall while being as reliable.
Maybe I don’t need an active electromagnetic fastener, but a solenoid fastener.
Now, I won’t delude myself (this time): any method of which you choose to keep a structure together are just methods of sacrificing structural integrity over the convenience of repairing it.
Every method has its pros and cons, conventional screws, nuts and bolts also have them.
That being said, there are many, many ways of making screwless fasteners, a few examples:
- Hydraulic collet chuck/internal diameter clamp: ETP HYDRO-GRIP COMPACT - Hydraulic high precision toolholder Dine DHE Hydraulic Expansion Chuck - Cutwel TV (this one uses a screw to compress the hydraulic fluid, but you could do the same with a lever instead)
- Toggle latch: CL-100-LSPC Locking Push Pull Toggle clamp Toggle Latch Clamp Heavy Duty Self Lock For Cabinet Boxes Heavy Duty Type Toggle Latch
- Not a toggle latch/clamp, but that can work as one if you change it: On-load release hook RM RB 02 (prototype)
- Quick Change Fasteners: Quick Change Fasteners for Machine & Fixture Changeover | IMAO
- There is also the Japanese Carpentry technique that doesn’t use nails, screws nor welds, which every time that I look at it, it is called a different name for some reason. Hypnotic gifs animate traditional Japanese joinery techniques (PDF) Designing method for Japanese traditional joinery based on cluster boundaries defined by weighted spectral clustering and its application to mechanical joint design重み付きスペクトラル・クラスタリング境界を用いた伝統技能・継手の設計法と締結部品設計への適用 Eindhoven University of Technology MASTER Finite Element Analysis of Interlocking Timber Connections in Plywood Diaphragm Floors (I’m not saying you should make it out of wood, but that it can be used on other materials too)
- A similar thing to carpentry is those interlocking laser cut wood parts that you can build. How to Join Laser Cut Parts Without Fasteners | SendCutSend Joinery: Joints for Laser Cut Assemblies : 16 Steps (with Pictures) - Instructables CNC Panel Joinery Notebook - Make: Craft Corner: Laser Cutting Pt. 2 Sheet Metal Fastening: 2D laser solutions compilation #2
- I don’t know if this also counts as fasteners or interlocking fasteners, but you could also use ropes/wires. Like it is done in the construction of tents and securing cargo. laser cut leather using Falcon2 40w - YouTube 3 EASY ways to tie ropes together that everyone should know! [step by step tutorial] Bushcraft Shelter Structure Knot - Roof Frame Knot or Table Construction Knot – CBYS How to cord strap with tensioner Rope Ratchet Commercial https://http2.mlstatic.com/D_NQ_NP_2X_811066-CBT77178910644_072024-F.webp DIY Rope Tensioning System - Super easy 3 minutes project - New invention - Bushcraft Rope Tensioner https://www.youtube.com/shorts/sDhHuPWtnp4?feature=share https://www.youtube.com/shorts/34xKCsNkJgE?feature=share https://www.youtube.com/shorts/28ehY6VTXWQ?feature=share Maybe this idea won’t be good enough, I just remembered that ropes/wires can get loose on their own, and you would need very specific (and expensive) ropes. Information was taken from this video: High precision speed reducer using rope Or maybe I’m overthinking it, rope/wire/cable bridges are a thing, and although they need re-tensioning over time, it is not like there will be a significant issue with a small structure like this one.
- Solid velcro: 3M™ Dual Lock™ Reclosable Fasteners: Bowling Ball Test
- Electroadhesion (you need to add power just once, unlike electromagnetic adhesion): This Video is About Electroadhesion. Accurate Electroadhesion Force Measurements of Electrostrictive Polymers: The Case of High Performance Plasticized Terpolymers Design, fabrication and testing of electroadhesive interdigital electrodes A mechanics-based approach to realize high–force capacity electroadhesives for robots A Cost Effective and Light Weight Unipolar Electroadhesion Pad Technology for Adhesion Mechanism of Wall Climbing Robot (wall-climbing robot using electroadhesion) Magnetic Augmented Self-sensing Flexible Electroadhesive Grippers (this one shows a mixture of electro-adhesion and electromagnetic holding) Reversible electroadhesion of hydrogels to animal tissues for suture-less repair of cuts or tears | Nature Communications (this one is about using electroadhesion for “suture-less repair of cuts or tears” of organic tissue using hydrogels, maybe it could be used as a suit for the second-skin idea?) Adhesion State Estimation for Electrostatic Gripper Based on Online Capacitance Measure Design, fabrication and testing of electroadhesive interdigital electrodes
Electroadhesion looks interesting, BUT it can only achieve 1 Newton per square meter. If I wanted to “glue” 10,000kg, I would need an electroadhesive surface with 5 square meters (or 50,000 cm²) of surface area.
If you made a 20cm thick tape with 5 m² of surface area, it would have 100 meters of length. Even making wacky shapes with it, I don’t think it would be feasible to keep it as compact as possible…
Well, I’ve made a rough calculation, if you had 15 cylinders with spherical tips around a 50cm diameter circle you would have almost 10 square meters of surface area.
Maybe this will work out depending on where it is applied.
In any manner, the adhesion is based on the breakdown voltage and electrical constant of each material, not so much dissimilar than a Dielectric Elastomer.
… That would literally work like a f*cking Lego set!
Wait… If it can attract… And adhere… Can’t it also repel an object if it has the same polarity facing it? Just like electromagnetic bearings?
And wouldn’t it also not require to be constantly powered? Just like electrostatic adhesion?
Well, I could only find electrostatic bearings for micromotors and electrostatic levitation for really light materials…
Levitating Objects Using 200,000 Volts Of Electricity! ( Electrostatic Levitation )
… I will admit that I don’t know enough about physics to think that there is something that wouldn’t make it work, even with the detail of the shape of the aluminum foil he talked about.
Example:
DEMO: Electrostatic Attraction and Repulsion
Controlling the shape of the bearings, you can control how they will repel each other and in which direction.
On the Subject of Structure:
- Just so I don’t forget it:
I'm copying a 40 ton hydraulic cylinder that I saw on aliexpress, it has 10 mm of wall thickness and its shaft has 110 mm of thickness, the outer diameter is 200mm and the inner diameter/bore is 180mm. So, I’m assuming that a solid cylinder with more or less 110mm of diameter or a hollow cylinder with 10mm thickness and 200mm of outer diameter would be able to survive 40 tons.
It also weighs 50 kg in total (more or less).
The idea is by copying these dimensions in order to make the structure, I will achieve a predictable result similar to the cylinder.
A common steel tensile strength for hydraulic cylinders is 700 MPa, and this is just the maximum tensile stress that it will suffer before failure, so a material with half of that value will have half of its strength, 20 tons.
Depending on the material used and its tensile strength, the average strength will also be reduced proportionally. So on and so forth.
Aluminum 7075 fatigue strength is 159 MPa while stainless steel is from 300 to 600 MPa. If it was solid aluminum, it would support around 10 tons maximum and weight 168kg in total if you used 10 of these.
Aluminum is really poor in fatigue, huh?
Training high-strength aluminum alloys to withstand fatigue | Nature Communications
Improvement in Fatigue Resistance of Aluminum Alloys by Surface Cold-Working
Improving the fatigue strength of A7N01 aluminum alloy by adjusting Si content - ScienceDirect
Architecture of high-strength aluminum–matrix composites processed by a novel microcasting technique | NPG Asia Materials (you could replace the titanium with stainless steel by the way)
Strengthening aluminum matrix composite with additively manufactured 316L stainless steel lattice reinforcement: Processing methodology, mechanical performance and deformation mechanism - ScienceDirect (just like in this article)
(PDF) Composites of Aluminium Alloy Matrix Reinforced by a Steel Mesh (or this one)
Self-Healing Aluminum Metal Matrix Composite - Tech Briefs
I know that this is too overkill, but I’m no engineer, and this is a safety factor of around 10. A competent engineer would precisely predict all the ins and outs of dynamic structures like that of vehicles (and robots), and I’m neither an engineer nor competent.
… But… Even when I check calculators online, an impact/tension or other loads applied on a random cross-section of this structure, even with values reaching 5000kg per 0.01 m² of area (10x10cm), less than 10 MPa is suffered throughout the structure.
But I don’t know how to tell if this is applicable to a three dimensional object…
- About the structure:
I found out about two interesting things about wood and carbon fibers. I know I already gave up on the subject, but I think these two things may make it viable.
Wood Welding:
First, friction welding of wood.
When you use high friction, like rotating a piece of wood into another, the lignin in the wood can’t react with the oxygen and combust/decompose, so it literally melts the lignin in the cells.
Yes, lignin is a type of polymer, a plastic.
He even uses a laser to melt a wood stick in a vacuum chamber in order to melt and bend it.
That means that you could melt wood in a mold just like plastic (I think).
(Yes, you could take a lot of sawdust, compress it and use friction welding to bind everything together, but I don’t have access to that kind of equipment)
Such as plastic, you can use additives and other materials to make composites. Like graphene, resins, carbon fibers, glass fibers etc.
This way you could make something as strong as aluminum, just like HDPE + PE wax + graphene powder that I was intending on using. But unlike HDPE, wood can be easily sourced.
You would need to take wood chips and/or fibers/sticks in order to fill in a mold, heat it up in the absence of oxygen and you have a “plastic wood”.
I also thought of using the sodium hydroxide bath that is used in the process of making densified wood, but that process is meant to make the wood more porous so you can crush it. It is easier to just powder it to dust and then “weld” it together like in wood welding.
Making wood as strong as steel!
In the article below it is shown that stabilized wood (wood impregnated with a resin, like acrylic etc) can achieve 600 MPa of tensile strength, so half of it would make it as strong as aluminum, just like the HDPE composite.
The strength and stiffness of oriented wood and cellulose-fibre materials: A review - ScienceDirect
The article in question: Strong Cellulose-Based Materials by Coupling Sodium Hydroxide–Anthraquinone (NaOH–AQ) Pulping with Hot Pressing from Wood | ACS Omega
“The as-prepared CBM exhibits a record tensile strength as high as 773 MPa and a modulus of up to 21.7 GPa. The strong strength of the resulting CBM was primarily due to the good orientation of wood fibers in the longitudinal direction as well as the increased numbers of hydrogen bonds among adjacent fiber cells resulting from the lignin removal and mechanical pressing.”
Well, in both cases, they needed to compress conventional wood blocks and/or infiltrate the piece with polymer (like acrylic). So I don’t know if melting the entirety of the wood in a new shape would achieve the same results…
I can also use bamboo fibers or other types of fibers for the wood composite, like a carbon fiber epoxy composite…
I find a lot of conflicting information about wood welding, in some it says it melts the wood, in others it is said that melting wood is impossible.
As far as wood-welding goes, It seems like it can only be done through vibration, either ultrasonic or mechanical.
From this article: The role of lignin in wood working processes using elevated temperatures: an abbreviated literature survey
“At the beginning of the welding process, Coulomb friction causes the surfaces to heat up. After a few seconds (3–10 s), at a temperature of about 320–350 °C, the wood surfaces start to decompose at the increased temperature. The temperature of 180 °C is reached quickly at the interface/surface but at less than 1 mm below the interface, the temperature is still 20 °C lower (160 °C). The wood next to the rubbed surfaces starts to soften, forming a viscous film. After reaching the maximum temperature about 420–450 °C, the frictional movement is terminated, and the joined parts are held together. The final cooling down leads to solidification of the interfacial film forming the connection between the wood parts. No preparation of the welded surfaces is required and the time necessary to complete the bond is shorter than one minute.
The mechanism of welding, in addition to the chemical reactions that take place due to the temperature-induced softening, is chemical activation, flowing and solidification of the intercellular material, mainly amorphous polymers: lignin and hemicelluloses. This flow of material induces high densification of the bonded interface. The physical entanglement of the fibers interconnected as a result of friction can improve the connection. In the brief pressure-holding phase immediately after welding, chemical reactions occur. The main reactions are the formation and self-condensation of furfural and the cross-linking reaction of lignin with carbohydrate-derived furfural.
Sun et al. (2010) suggested that the chemical changes when applying friction welding are similar to changes during fast pyrolysis at a lower pyrolysis temperature. This is a transformation of a nonvolatile compound into a volatile mixture by heat in the absence of oxygen. During these processes, bonds are broken, free radicals are formed, which re-polymerize and create side-chains. In these temperature ranges, only the amorphous components of wood are affected, particularly lignin and hemicelluloses, and to a lesser extent, amorphous cellulose. First, hemicelluloses degrade through acid hydrolysis and dehydration, which starts above 100 °C, but the weight loss of hemicelluloses takes place mainly in the temperature range of 220–315 °C.
…
During friction, a new lignin-carbohydrate complex is formed from the condensation reaction between lignin fragments and furfural derivatives from hemicelluloses. Belleville et al. (2018) found that a higher proportion of lignin seems to be favorable to condensation reactions during the welding process. According to another observation, fatty acids, terpenoids and other extractive compounds form covalent bonds with hydroxyl groups of other compounds. There is a degradation of fatty acids, which deform to carboxyl acids, mainly citric acid, which can improve the mechanical properties through chemical linkages. The work of Ganne-Chédeville et al. (2008) summarizes the processes that take place at different temperatures during welding. The main components of the smoke emitted during welding are water vapor, CO2 and decomposed compounds from wood polymeric carbohydrates and from lignin. Delmotte et al. (2009) found that by increasing the welding frequency from 100 to 150 Hz, the oxidation of the components decreased due to the much shorter welding time, which improved the joint strength.”
At this point I’m wondering that the faster you heat it, the lower the chances of it oxidizing and/or decomposing.
… So a better method would be to apply a really high voltage super fast?
Wouldn’t that make graphene tho?
Out of curiosity, friction welding of wood also works with paper and fibers.
If Wood Welding fails to make a strong material, I can just use the stabilized wood material.
Even though I wouldn’t be able to make a homogeneous part like I initially planned, I could always use steam bending of wood and the friction welding in some parts for structural integrity.
… Or maybe not…
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