My Advanced Realistic Humanoid Robots Project

Here is a progress update on the silent pulley downgearing system I came up with using thumb tacks and a #2 fishing crimp sleeve and little plastic discs. It is some tiny fine precision necessary work but I'm getting it done and things seem to be looking pretty good so far.

For now, I ended up just using 401 glue to glue the thumb tacks down onto post it note paper. I then put another coat of the glue over the tops of the thumb tack heads to secure it further. I am planning to use nylon upholstery thread lashings to lash all the tacks down onto the top of the 2430 bldc motor tightly and glue the lashings down as well in order to make the thumbtacks even more solidly set into place. Now I'll grant welding them down would be ideal, however, not having a micro tig welder made yet (future project), I just wanted to get going fast and I thought with enough care, it is possible these can be constructed solidly enough with composite material techniques to function reliably. I'm crossing my fingers. We'll see.

Okay, so I finally got the Dinah robot hand sewn in and it is looking pretty good. The fingers could use some tweaking but overall I'm quite happy with how it came out. It's solid and fully articulated.

Here's a photo of it in place:

Now that out of the way, I want to announce I'm officially canceling the Dinah project as far as its current goals and here's why: so basically I was thinking it would be nice to just crank out a working robot using some shortcuts and just do something quick and dirty as a learning experience side quest to get something going. It seemed reasonable at the time. Plus I could pace myself to match the build pace of a fellow roboticist and loosely follow his project's designs. But some things I missed in this decision: #1) I'd be lowering my commitment to excellent quality with no shortcuts - ignoring the adage "do it right the first time" #2) by cutting down on workmanship maxing, I'd be inviting harsh criticism on the new lowered bar of build quality which is the last thing I need when already inviting heavy criticism for a extremely ambitious set of goals to begin with #3) I'd be going against my outspoken commitment to campaign against loud metal gear noise based robots that are completely impractical for home use due to sounding like a construction site #4) it would take away from the focus on my "real" robot projects by creating a "ghetto" side quest robot that could have just been skipped altogether. #5) this would in turn delay me truly solving downgearing by pulleys and actuating the robot arm silently once and for all, proving it can be done and proving that achieving a fully human level DOF human hand and arm while maintaining a human form factor and making all of this silent can and should be done for humanoids.

So is Dinah robot just trash now? No. I still plan to have this project be done, but like Adam, it will be shelved until such a day that the other robots, when ready, complete building these shelved robots for me. And when they are built, it will be using the best methods I have including silent BLDC motors with silent pulley based downgearing. So I'm returning to work on the Abel robot whose arm will build the rest of his own body and then he will build the Adam, Eve, and Dinah robots for me.

I'm currently working to sew all the finger and wrist bones together for the Dinah robot and mount them to the arm. I wanted to show how I'm doing this process.

Here I tape the bone with adhesive transfer tape 3M 300 LSE. Note that I leave space on either end of the bone to allow some free fabric which is necessary to allow for elasticity as the bones need to rotate after all. Have to have enough free fabric to stretch as the joint rotates, allowing the rotation. But not so much free fabric that the joint is loose either. Has to be just right and snug.

Next I wrap the compression workout shirt fabric onto the tape and cut it to size. Here is just a rough wrap that hasn't been cut down to size yet.

Then here is a bone finished on the sewing and ready to attach to a neighboring bone. The sewing is done with nylon upholstery thread and a curved suturing needle and a surgical pliers using a suturing technique.

So I finally got the wrist done. And aside from grinding off welds on bolts and backing off the bolts to allow for free movement at joints, I'm mostly going to try to keep this skeleton stock for the most part. So I may be attaching the hand and going immediately into electronics rather than fiddling with the skeleton adding more range of motion here and there. I can always add that later anyways. And in fact the poseable joints that are fairly stiff I'm finding is actually pretty convenient while working on it so I may only free joints on an as needed basis for testing electronic actuation of that joint. Until then I'll leave them alone.

Also note: I was planning to have the wrist rotate axially around the location of the wrist for the pronation and supination. However, I realized this will not look right since you can visibly see the forearms move and the muscles there moving when you pronate and supinate your arm. So I have to have the pronation and supination be where the skeleton was originally doing this near the elbow. This will allow for much more natural looking pronation and supination. So the wrist location will not rotate AT ALL after all. This made it all the easier to make the ulna and radius distal wrist joint where the little wrist bones and hand will attach to and rotate on. I sculpted it all in fiberglass and super glue with some nails and some ABS plastic pieces and epoxy to build up the shape. I used my ABS 3d print of this part as reference only. This thing needed to be very strong as it's likely going to the point of failure as the rest of the arm is steel. So I wanted to make sure it was maximally solid and didn't fully trust just going with a 3d print there.

In these photos you can see the progression of going from the stock wrist to an axial rotating wrist assembly acting as a plain bearing. Pardon the Orgrimmar welding - it's a cheapo welder.

The process involved cutting the bolt head off then grinding smooth the threads and then sliding on a stack of washers and welding the last couple washers into a mushroom head end stop then welding the other washers to eachother and these ones are to spin freely. They will do the pronation and supination. This replaces the need for a ulna and radius for that purpose, simplifying the skeleton some.

The metal outcroppings I left on the washers were meant to jut out significantly to give the fiberglass something to bite onto well for a dependable attachment.

Note: The stock skeleton does rotate axially already at a spot just near the elbow but that rotation is stiff and requires significant force to get it to move and loosening it is something I don't know how to do. I don't even know how it works at all. Advice on that for future reference would be helpful.

Note: There is too much clearance on the stack of washers so they can slide distally or proximally a good 8mm which is not okay - too much play. I need to fill that gap and lube it all with white lithium grease.

Note: I'm planning to probably just go fiberglass wraps over and over onto the stack of washers to grip it tightly and build outward from it and then go out and around the welded mushroom cap and then wrap onto the ABS wrist ulna/radius fused section.

Also note that I have reconsidered adding a dual hinge to the elbow joint and lean now toward just leaving it stock. I think the double hinge would add complication to the bicep attachment and cause some issues I'd rather avoid. A single hinge is easier to deal with IMO.

I managed to get Dinah's hand bones printed out in ABS on my Anet A8 3d printer the past couple days. I also cleaned up the prints, removed the supports, and sanded down high points. They are ready for attaching them together with cloth tape which will act as artificial ligaments.

You'll note I fused the ulna and radius bones together to use as a rotational joint for the wrist to function like a human wrist. The actual pronation and supination of the forearm though will happen by way of the steel skeleton having a rotating pivot point unlike the human body where the radius rotates and twists over the ulna in a criss cross.

Note: in this photo the middle finger is missing the distal tip which I was reprinting as the time of this photo.

The Dinah robot is coming along well. I modeled the full steel skeleton in CAD to match the dimensions of the Dinah base mesh and created a human bones variation as well to compare that to the steel simplified skeleton and make sure all the joint pivots matched the locations of the human skeleton joints pivot points. With this CAD, I will be able to modify the proportions of the steel skeleton I have on hand. I also added several key additional joints using reference photos of a skeleton I found online. For example I now have 2 pivot points for the knee joint instead of one which gives more clearance when knee bends back. I also gave a few more degrees of freedom to the neck and shoulder area. Here's the CAD:

Note also that I am well on my way to finishing up printing ABS solid infill fingers and wrist bones which I will retrofit onto the steel skeleton so that I can have full 27 degrees of freedom robot hands and wrists to match perfectly the dexterity of the human hand, which is a must.

I have decided that once I finish the arm and head, I will not go on to complete the building of the rest of the robot's body but instead will switch my focus to the AI entirely from there forward. I will code the AI to cause that arm and head to build the rest of its own body.

I just came up with a cool alternative way to downgear a 2430 BLDC motor that might work.

Here's a illustration of the cheap downgearing idea:

So basically, I figured what if I could remove the N20 motor from its gearbox/"gear set" by cutting it free or w/e. But I keep its center axle in place cutting away only everything else. You'd then presumably have a metal shaft as a entrance to the gearbox and a metal shaft exiting the top of the gearbox. I then turn that metal input shaft and output shaft into pulleys. I feed my 2430 motor output shaft pulley/winch into the input shaft of each of 4 N20 motor gearboxes, evenly distributing the load. Each gearbox downgears my 2430 motor 150:1. Each gearbox chatgpt said could handle about 5-6lb load but this can't be sudden or fast direction change this is really pushing it. But it seems 4 gearboxes should handle most of what we'd want from a 2430 motor. And the fact we can fit them all within the height of the motor output shaft default length and within the width of the 2430 motor diameter for the most part seems it would be a pretty significant downgearing for very low space taken as the cost. You could even locate a few more gearboxes off the motor anywhere and have those fed further distributing to them the load if only 4 gearboxes was not enough to handle expected forces. The cool thing is supposing we did this, it would cost us four N20 motors which is $0.80x4 = $3.20. That is VERY cheap for a gearbox as I read that a planetary gearbox for it would be like $25-30! And the planetary gearbox would take up WAY WAY WAY WAY more space which is highly coveted in our application - space we can't afford to spare. And the great thing is these little gearboxes you can fit ANYWHERE into a nook or cranny since they are so tiny... and you can use as many as you want to get up to the total forces you need them to handle as a collective. Seems like this could be a cool technique. I want to give it a go. Any thoughts?

Note: this would be something I'd try on the Dinah robot where I'm using metal gears despite the noise these create since its a lower budget simpler robot I'm doing just to get something done faster for a change. My Adam, Eve, and Abel robots will be going pulleys to downgear to make them very quiet in operation as has been the plan forever.

So today I went ahead and extracted this metal skeleton from a male love doll I had bought some months back to use as a base form from which to sculpt the appearance of another robot.  Just to clarify upfront, this was never purchased for any sexual purposes—strictly for its materials.  I bought it mainly wanting the already decent human appearance it offers in the TPE body and face that can act as a starting point for sculpting a robot. This is better than having to begin sculpting from scratch in clay and making a mold or w/e. Just a shortcut for me. I bought a decent used male love doll for a few hundred dollars which was a bargain to say the least. The shipping alone had to be close to $200+ so it was priced WAY below the cost of the raw materials if I were to try to buy 50lb of TPE rubber. I intended to melt down the massive amount of TPE rubber once done using it to assist in the sculpt of another robot and use that melted down rubber to create the skin for a robot. So those ideas were I had planned for this doll. However, now that I have decided to use the skeleton for a robot build - now I'm REALLY maximizing that little investment! So after 4-5 hours of carefully removing the skin from the frame, I have it all off. I made a few tears here and there in the doll from rough handling during the skinning process and the lack of experience at this, but it went well overall. It was a very physically demanding job to separate the skin from the frame since you had to pry at it, cut it, and peel it and the whole time it fights you wanting to snap back to its original shape. I am quite sore but glad I got it done in a single day.

Here's a photo of the skeleton I just extracted and will be modding and using for Dinah:

Now, having gotten the skeleton out and analyzed it carefully, I noticed it does not have the ability to shrug, so I'll have to add a hinge on both sides to enable that movement. Also, its bar where the tibia and fibia would be is not proportional in length to the bar that acts as the femur. I can see that they made the doll taller by just adding length to the tibia/fibia bar rather than proportionally adding height throughout the robot. So its proportions are off due to their laziness or oversight. In any case, I have to modify ALL the proportions some I think to match the proportions of my Eve base mesh sculpt. The neck is also quite hard to bend so I might have to add a couple hinges to it. All the nuts for every hinge on it are welded into place to prevent them backing out so I will have to grind off all these welds so I can loosen the nuts to disable posing and instead have all joints freely moving to reduce friction. I will have to add proper fingers and a palm. I will 3d print these bones for the fingers.



TheRobotStudio is using Feetech SC0009 servos for the fingers. I'm planning to substitute in three N20 66rpm motors in place of each Feettech SC0009 servo. By combining three of these N20 motors, I am able to surpass the total torque of the SC0009 servo but after factoring in the size of our respective output winches, mine will be about 13% slower than his. This is fine by me because his robot hand designs are always extremely fast in finger speed and I can get by 13% slower than this. The purpose of swapping in N20 66rpm motors for the Feetech SC0009 motors is to cut costs and I just have a ton of them already and have been itching to use them. The Feetech SC0009 servo is around $11 and my N20 66rpm motors are only around $0.80 so 3 of them is $2.40. So that's $8.60 saved ever time I do this part alternative strategy. Well the savings is a bit less since I then have to supply my own motor controller H-bridge chip and potentiometer to read joint angle. So maybe only $8 saved. However, from what I gather, the Feetech SC0009 requires a serial adapter board to run it and doesn't use PWM but uses serial. I do NOT like this AT ALL in terms of my preferences and the adapter boards were $13 each and only serve 4 servos. That will add up quickly. So I'm actually saving that cost too. I prefer my microcontrollers to pwm directly to the h-bridge with no middle man software whatsoever to maximize my control.

TheRobotStudio is using 3 different sizes of Feetech servos in his approach. You can see the wrist servo is much bigger in his CAD model. I am operating under the assumption I can cram TONS of these little N20 66rpm motors and use more than one of them per joint. So I can use as many as I need to get to the torque I require. I will use L298N motor driver h-bridge chips with these N20 66rpm motors to drive them. This chip can safely power 2 N20 motors per channel and has two channels. It's VERY cheap maybe like $0.15 per chip I think - don't remember. I'll use Arduino mega to send out the pwm. I'll use 10k ohm 3 pin wheeled potentiometers to read the joint angles and these will be coupled to the joints by fishing line which will translate the joint angles over to the potentiometers whose values will be read in by the Arduino Megas. So a lot of my own designs for control and sensory input I'm sticking with for this project but using various elements of Hope-Light for a hybrid approach and swapping in different actuators whenever I feel inclined.

TheRobotStudio on YouTube is doing an open source robot called "Hope-Light" and inviting his viewers to follow along with his progress . I have decided to follow along, although I will be modifying his designs as I go to customize it more to my liking. He expressed he wants this to be a open source community to advance humanoid robotics development in the DIY space and usher in the wider adoption of humanoid robots in more homes across the world. He's excited for what this can mean for global productivity and quality of life improvements it can bring if executed well. I like this vision.

My decision to follow along with his project is to pick up a extra head of steam in my own humanoid robot building projects by utilizing his experience and formal education in robotics engineering as a legit decorated world class humanoid roboticist. A world leader in the field. By following his open source project loosely, I can get a breath of fresh air by skipping past the bang my head against the wall dead-ends and regular difficult hurdles and just get results. Sort of like fast food drive thru. It will be a relief for me. And confidence booster. To see something really happen at a faster pace for a change.

Now none of this is to say I'm abandoning my existing projects. They will all go on as planned without interruption. This will be a parallel journey I will share. I will certainly learn a ton and can apply what I learn to my other projects.

I will have this Hope - Light robot adaptation be named Dinah. I'll use Eve's base mesh for the external appearance. The two females can look similar in build but have different faces.

This robot will use to some extent TheRobotStudio's design philosophy and approach for the Hope-Light project. This means it WILL use metal geared brushed DC servos and it WILL use non-human-like bone structure, but I will still give it human-like realistic silicone skin and it will use the exterior exoskeleton shell of the Eve robot I 3d modeled already. One downside to this Hope-Light parallel implementation is that because it uses metal gearing it will be loud in its operation. So it will never be able to pass for human in public. That's okay though. My other designs are reaching for that aim and my other designs are still the intention for Adam, Eve, and Abel. So that vision remains alive. And will continue. But this noisy robot will still be a great learning experience and capable of doing useful work including helping me build my other robots, chores, manufacturing products, cooking, etc. It will probably do most of the things the Adam, Eve, and Abel robot can do but not be as strong, fast, and articulated. So it will probably not play sports well or do rock climbing or various other serious physical strenuous types of work. But the long list of things it should be able to do is still enough for it to be awesome.

A great thing is that it won't be so experimental and outside the box like my previous solo approaches. This one will be designed to a small degree by a real professional so it will happen way faster and more surely than mine. Although I am finding I am changing his design so much it's not really his design at all anymore but my own. However, I still plan to retain a significant number of strategic decisions, placements, and organization following his lead. My other designs are more of a pipe dream shooting for the moon. Going more similar to this open source one designed by a real pro is more of a "sure thing". Not that I don't believe I can achieve my more ambitious designs, but just that they are admittedly a taller order and more crossing fingers about them is all. I really think building a top tier legit walking and talking full humanoid is going to legitimize my journey more in my own eyes and give me a better resume to bring MORE hope toward my own robot builds. Just seems like doing this is a no brainer.

Here's a early design progress image from TheRobotStudio who is currently designing Hope-Lite in Solidworks.

You'll note he fused the distal knuckle of 4 fingers so they are permanently partly bent. This was a decision to cut down on complexity but in my preference, I'd rather have that functionality. You'll also note that it cannot pronate or supinate the wrist. That takes away a TON of functionality which is not my preference. So my robot will add this function back. That said, as I was studying how to add pronation and supination without a ulna and radius bone, I stumbled across the simple and effective design of posable love dolls' skeletons. I realized they have pronation and supination in their stock skeletons, so I decided I will use that kind of skeleton for this project. They are simple, very strong, welded steel construction with heavy duty hinge systems. To be posable, the hinges are quite stiff, so I will need to loosen all hinges to reduce friction. They are a hollow lightweight tubing style. Actually not that heavy.