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Software / Re: software that rids the need for motor positional encoders
« Last post by greyfoxy123 on Today at 06:24:42 AM »
I?d love to dive deeper into this since getting rid of encoders could really open up cost-effective options for robotics. Thanks for sharing your thoughts so far!
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Mechanics and Construction / Re: My Advanced Realistic Humanoid Robot Project
« Last post by artbyrobot1 on January 08, 2025, 10:29:35 PM »
Here's my latest progress on the winch in place pulley setup. I opted for 10lb test 0.12mm diameter PE fishing line (orange color) as the output that will interface into the first pair of downgearing pulleys of my archimedes pulley downgearing system.



This turn in place pulley achieves 2.77:1 downgearing ratio now. The motor shaft reels in 32 inches of string that is 6lb test 0.08mm pe fishing line (black) and after the downgearing pulley, the final amount of orange fishing line reeled in is 11.55". That's a much more manageable amount of runout for the archimedes pulley system to deal with to keep it more compact.

The archimedes pulley downgearing system will add an additional 16:1 downgearing to this which brings me to a total of 44:1 downgearing. The motor itself pulls at .5lb pulling force so after 44x that increases to 22lb of pulling power. After mechanical disadvantage is factored in, I estimate the finger can curl 5.5lb ideally which is about the same strength as my finger. So that's perfect and VERY strong IMO.
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Mechanics and Construction / Re: My Advanced Realistic Humanoid Robot Project
« Last post by artbyrobot1 on January 03, 2025, 12:40:44 AM »
I've had an epiphany. So in the winch in place pulley system I was working on before, my concern was that when winching in the string things would be taught and reliable but when the motor reverses and releases string, that is when any snags in the system could cause the string to not be taken up rigidly and tension on the system is then lost and the motor is then unspooling string which isn't being taken up which will result in a spaghetti mess of string spraying everywhere out of control and getting all tangled up. The solution I had was a constant tension spring attached to the turn in place pulley output that would ensure that always keeps the string in tension as the motor unwinds. However, that was a extra cost and complexity and volume taken up by yet another thing and when you multiply that out by 300+ motors that's a LOT of springs added taking up a ton of extra space. That is why I moved to a belt based system instead of string and winch based for the first pulley. So the epiphany was this: it hit me that I can simply have the spring that does the extension of the final finger joint be what puts tension on the whole system and then if at any point in the system a snag were to happen, rather than tension being lost as the motor blindly unravels, not detecting the snag, I could have the motor NOT actively unwind anything at any point! So the motor, when unwinding is to occur, will simply turn OFF, rather than actively drive the unwinding electronically. It can pulse width turn off just acting as a brake to moderate speed of extension but at no point do any counter clockwise release or unwinding of the string. This way, the system only itself pulls string off the motor output shaft and if the system at any point snags, the extension stops and the string is all still under moderate tension but just no further advancement takes place and the motor does nothing further but blindly turning on and off but not actually spraying out thread everywhere at all. Eventually, the potentiometer measuring the joint angle of the finger joint would detect things are not moving and the system would KNOW it has a snag somewhere and at that point it would perhaps try to contract then attempt extension again hoping to dislodge the snag. If this did not work, the system would go into a troubleshooting routine like notifying the user (myself) to fix it or fixing it itself or w/e. But no damage would occur in this setup involving a unraveling mess or tangled mess. Simply the snag itself would be discovered and addressed but no catastrophic series of failures would result in theory under this new setup.

So with all of that said, and this solution in place, I am ready to return to the turn in place style winch style first pulley setup I had before and then the Archimedes pulley will do the rest. So the first pulley will be 2:1 downgearing and the Archimedes system will do 16:1 for a total of 32:1 downgearing. No constant tension spring needed anymore! Much simpler now. Everything I was concerned about is then solved now.

The belt based system fix ideas I was going for may have worked but as of right now I'm abandoning that course. I prefer the winch style and think belts would be higher maintenance and slippage would perhaps be an issue even with all the changes I had mentioned to improve on it. The fact is, belts only have so much surface area to grip onto so they don't scale down too well to tiny pulleys IMO. Large pulleys are better due to large surface area and more for the belt to grip. So my super miniature belt idea was a bit doomed from the start even if it could have worked (and it may well have worked) it just isn't ideal theoretically and I'd rather go with something I trust more intuitively for now.
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Software / Re: software that rids the need for motor positional encoders
« Last post by MagnusWootton on December 23, 2024, 02:14:15 PM »
So me a bit later...

you can actually get a robot to stand.   with a pitch joint,  you know the direction!!! towards the ground and away from the ground.

So if u keep pushing down till the accellerometre tilts away from the leg, you know youve hit the ground.

Then if u do it with all 4 legs,  wait for the right elevation and centre angle,   and u know if u need to push down,  or stop pushing down!
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Mechanics and Construction / Re: My Advanced Realistic Humanoid Robot Project
« Last post by artbyrobot1 on December 14, 2024, 03:11:19 AM »
Ok so my belt drive system from my last update just is not quite up to par in terms of grip and anti-slippage. So my new series of changes are planned out and underway now. First, I will be bumping up the height of each pulley to 2mm up from 1.1mm. This will double the surface contact area for way more belt grip in and of itself. So then I can use a 2mm wide belt. Next, I'll be increasing the drive pulley diameter to 1.5-2mm additional diameter. This will also greatly increase surface contact with the belt for more grip. Then finally, I'll be using a commercial belt that is said to have the highest grip of all belts - its called a polyurethane belt. It is a flat belt with 2mm width and .9mm thickness. It should be a huge upgrade to my current setup! Here's some photos of it:


The best part is you can customize the diameter of the belt by melting the two ends together! This was a key thing I did not know! So I can create just the right size and it should be perfect! I can also double these up by melting two belts layer by laer for a 1.8mm thick square shaped belt that is even less stretchy and so can be even more able to tightly grip my pulleys. I'm very excited about this and think it will take us to where we need to be *crossing fingers*.
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Software / software that rids the need for motor positional encoders
« Last post by MagnusWootton on December 12, 2024, 09:33:20 PM »
Making encoders is a bitch, and dc motors are cheaper without them.

So it would be cool if u could get a robot to work without them.

Its a seemingly impossible thing,  cause a legged robot cant even have a centre point for its motors to even just stand still!    If you put mechanical end stops, then you can at least know the end point positions,   that could help.

If you dont have positional information, the trick is maybe u could correllate it from accellerometre information over time,   so you exchange the positional information for so many accellerometre samples and maybe its equivilent information!

So u just need to correllate it,  with machine learning.

Its actually a little of a long story to explain it,    but I think its possible!   U just need to get in the right semantical/generation space to make it happen.

So if you take it from the position of searching inside of a physics engine (as the generation space), you predict the next accellerometre accelleration, from a chain of accellerometre data, and u step it each new frame,  and the chain of accellerometre data is replacing the lack of angular position information, but it should be equivilent.

Then that should build the virtual copy of the physics, which lets u then brute force the robots motor commands to get the robot in action,  WITHOUT encoders! :)
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Robot Videos / some robot videos
« Last post by MagnusWootton on December 12, 2024, 09:05:54 PM »
I've been wanting to put a robo together for years now,   but I'm really sick from smoking cigarettes so I still haven't got it finished.

I've got a really cool innovation I want to share with you guys about getting rid of the motor encoders and how it shouldn't matter, robots dont actually need them!!!  I'll bring it up sometime here in the near future.


This is work over the last couple of years->


Heres a virtual sim of my bot going (I paid a bit of attention to the look of the graphics.)  But the main thing is the physics being correct, and its a bit dodgy still, the robot is just moving with random motions.
The end product would be the two robots having a fight on screen, in a virtual environment.

https://www.youtube.com/watch?v=XdIJCjYODZw


Heres another one with the graphics taken off, of the two robots upside randomly moving.

https://www.youtube.com/watch?v=coJcZKJNLKQ



(Computer vision)
heres a stereo rgb -> depth map on the gpu.  (ran pretty bad, theres alot of matches to do!)

https://www.youtube.com/watch?v=deRUU9j-uTU




Heres a little robot kit i put together and got some random movements out of it->

https://www.youtube.com/watch?v=LJfyyzP7ec8
https://www.youtube.com/watch?v=Hw6Q9GOrRnk
https://www.youtube.com/watch?v=wmVr-beVAJY
https://www.youtube.com/watch?v=GJaMAWIcH-c



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Mechanics and Construction / Re: My Advanced Realistic Humanoid Robot Project
« Last post by artbyrobot1 on November 22, 2024, 04:32:23 PM »
Ok so I was struggling to plan out how the flat spiral coil constant force spring would maintain constant tension on my first winch in place pulley the past couple days and I was studying how tape measures use these springs. Then it hit me when a colleague was mentioning belt pulley based downgearing that a belt pulley based downgearing for this first pulley would remove all the issues of derailment and need for constant tension during whole duration of travel a winch style would require in this design. Also, since its just .4lb-.8lb of force for the first pulley downgear, as long as the belt is reasonably tensioned and has some decent grip to it, I should not deal with a ton of slippage issues and the motor's output should be passed along well. So here is my beginning attempt at converting my first pulley to a belt based pulley instead of fishing line winch based pulley.



This is made just using adhesive transfer tape applied to one side of a nitrile glove and cut out into a 1.1mm wide strip and applied to the two pulleys directly. Built in place.

Early testing shows it needs more layers to have less stretchiness or needs to be reinforced internally with fishing line wraps between layers to prevent so much stretch to it which causes slippage. Also, the motor output shaft acting as the winch pulley is a combination of a bit too small in diameter and a bit too smooth to create a proper grip. So I'm thinking of thickening it up some and adding a grippy surface to it so that it grips the belt better with less slippage.

I am considering using silicone rubber to coat the motor output shaft or several wraps of nylon upholstery thread and super glue to thicken it then coating that with carpet anti-slip paint. Or silicone.

I'm considering making the belt from a cloth coated in silicone or carpet anti-slip paint and then sewn tightly into place over the pulleys - creating a sewn seam for a tight grip.

I'm considering a tensioner pulley but I think that's overkill and should be avoided unless it proves absolutely necessary.

I have not explored purchasing options at this time but of course I'm open to look into this in the future. The thing about a premade is it would have to be a perfect fit in both length and width and I'm not sure if that will be easy to find or not. This is all a very new approach so I can investigate that later. For now I'm happy to just move quickly on the prototyping with materials on hand.
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Misc / Re: Hello from Brisbane Australia looking to connect with locals
« Last post by mcdonaldsfind on November 11, 2024, 02:41:18 AM »
I see there are many local competitions. I hope you find a suitable group soon.
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Misc / Re: Hi i´m new here
« Last post by endinvest on November 10, 2024, 08:50:07 PM »
Hello,
I'm also new, glad if I can connect with your project.
Could you provide some more information about it?
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