Experimental Wave Drive
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- čas přidán 16. 05. 2024
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I recently built an eight wheeled snake bike, and that was based on a smaller version I built some time ago. And before that I built a worm robot which moves by expanding and contracting. This is known as a system of Peristalsis, which from Wikipedia, is defined as a radially symmetrical contraction and relaxation of muscles that propagates in a wave down a tube.
While I was researching these projects, I came across another experimental robot which uses a wave motion, with the wave running down its body, to propel it forwards. This is a bit like how snakes actually move, Well, the ones without wheels or legs of course.
My original plan for this project was to make a surf board you can ride on the land, but using a mechanical wave like this to propel me along, and use a large set of mountain board wheels for steering. However, I thought I’d try to make a smaller version of this mechanism first so see where the potential problems could be.
It looks like the mechanical wave is formed by a thing that looks a bit like a giant corkscrew, which simply rotates inside a flexible track, so I 3D printed a former which I used to try to bend some wire around. I wanted this to be quite stiff though because in my version it has to support the whole weight of the machine, so I used 4mm diameter stainless steel rod. This was pretty hard to bend into shape by hand, and my resulting screw shape doesn’t quite match the former or the original CAD design, but we’ll see what problems that causes later.
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XROBOTS
Former toy designer, current CZcams maker and general robotics, electrical and mechanical engineer, I’m a fan of doing it yourself and innovation by trial and error. My channel is where I share some of my useful and not-so-useful inventions, designs and maker advice. Iron Man is my go-to cosplay, and 3D printing can solve most issues - broken bolts, missing parts, world hunger, you name it.
XRobots is the community around my content where you can get in touch, share tips and advice, and more build FAQs, schematics and designs are also available. - Věda a technologie
For screws - I used to work at festivals and agri-shows, we'd frequently pin tents down with giant screws that shape. You might have seen smaller ones used as dog-leash tie-downs in front gardens etc. The ones we used were a about 5' total length, 8" diameter coil with a full rotation every 10", just a bit thinner than rebar - should be ideal for what you want, although they were heavy.
Cool thanks
Another option for something large for the rideable is a spiral ligature - it's a spiral of rebar meant to be pulled out to a column and welded to vertical ties to support a concrete pillar. I'd guess you could weld 2 together in parallel to lock in the spiral shape. They seem to come in various weights and diameters.
Or possibly use an easier/stronger to make solid spiral on top of the tracks. Then the spiral focuses on the down force and bungee (or something else) does the up force.
Or you could use one of those big screws to shape the wire screw reliably
@@jamesbruton Also check garden supplies; they have such screws for climbing plants. Although I think those might be a bit big for your purposes, I think they start at about 4 inches diameter.
The creative output of this channel is so high, every month or more often you drop awesome projects, i wish i had even half of your work drive.
if anything he's too good at fabrication !! In this video I think James is overlooking what most people would do - find a good spring and then build around it
Making the wire one looked hard enough, let alone that tubing !!!
@@willdarling1 Exactly, I was thinking about those found in vending machines.
You said everything I was thinking better than I could. 👍
@@KeithZim Was thinking the same thing. Removing the foil/film of duct tubing, like that on a back of a laundry dryer would possibly suffice.
looks like this video was made just to make a place holder for commercials and not for something intresting to watch. as a tech person i was able to say that this shit doesnt work from the begining. .( This was first video that i saw from this chanel )
The reason why your mechanism doesn't work very well is that the length of the track is constrained. If you look at the ends of the tracks when they jam up, you can clearly see that the tracks are fighting with themselves.
To improve your design, you could either use a proper helical shape for the screw, or allow the non-driven end to slide back and forth slightly.
Just take the last link off, right?
@@brendanhenderson6999 That does sound like the simplest solution.
This with increasing the frequency will allow you to have one fast crawli boi
Even a proper helix would vary in length over the cycle, unless it was very carefully controlled to integer multiples of the total wavelength. The simplest and most reliable solution would be to just disconnect one end entirely from the frame - it doesn't actually matter which, since even when it was connected the load was going through the helix anyway - and allow it to take the form it wants.
@@iskierka8399 I think you're right in saying the ends of the helix must be positioned in such a way that the length of the helix is a multiple of the helix wavelength. Another point worth considering is that for the variation in the length of the track as it rotates to approach 0, it intuitively feels like the length of the track pieces must also approach 0. With that said, I don't have any proof for that and it could be entirely wrong.
You might get more traction and a more stable gait if you have more peaks of the helix touching the ground at one point which means maybe increasing length of the robot or decreasing the amplitude of the helix itself
"Work better if longer and slower " ahaha
Decreasing the amplitude would merely mean equal contact area spread over more surfaces. The end result would be nearly identical
@@jermihalia9418 Good point I think what I meant to say was increasing the frequency of the helix, not the amplitude.
I would agree with this. It should have 2-3 periods in the length of the helix. this would make the forward running smoother.
I think it would be good to also distribute the load horizontally between multiple synchronous helices (fitted in the extra space from the decreased helix diameter). At that point the track mechanism wouldn't need to be hinged to be as longitudinally torsionally stiff, it could be made form a more compliant structure (i.e. a sheet of bendy hard plastic stapled to the helixes, or multiple horizontal sticks strung together with cord).
Make the " screw" like an engine crankshaft instead of a true coil. Then you could put a bearing at each track piece.
Question: Couldn't you use the coils for vending machines to drive this small version? They're very uniform and precise and also rather rigid.
You are absolutely mad and it’s fantastic how you focus that energy
I'm always impressed by the creativity of your work and would like to one day, do a project of this caliber.
This channel has become the 3d printing locomotion testing channel I didn't know I needed.
I salute you James. Your imagination knows no bounds in what you are willing to attempt. You are the Caractacus Potts of the diy robot world.
Very Nice! In addition to having more links, and a longer period in the helix, I would suggest 3D printing longer 'Feet" (prongs, cleats, points, feet with legs, etc) on the treads. You can really increase the forward speed of the drive mechanism as the 'feet' will extend the motion of the helix. The feet will need to interleaved on neighboring treads to prevent collisions.
I am super glad to see you implement this mechanism. I have studied and made my own versions, it is really nice to see you put your spin on it!!
Put small round beads on the screws that freely rotate when in contact with the tread. Much less friction and smoother operation.
that's brilliant! not only would it reduce the friction but also could add a sort of suspension if made from TPE or similar
Colin Furze's Screw Tank design used a left hand and a right hand threaded screw and to drive forward they were driven in opposing directions, I think that method would reduce the amount of wobble while also adding accuracy to the steering. Also there must be a calculation to the wave height to length which would optimize ground contact and speed.
If you are looking to make a coil around bar stock, heat the coil while you bend it and keep it on the bar when you stretch it so it maintains the diameter while also tightening down any imperfections or variations on height. Or again borrow from Colin's design and use flat stock around a centre barrel/pole.
Either way, you will figure it out and make a design that is brilliant, as always!
You could also explore this idea making a track from servo-powered links like a snake robot, then having various wave motions programmed into the track with a microcontroller. Maybe a bit expensive for a ride-on size machine but interesting for a smaller one.
that would be super cool though!
I get the feeling that this needs some compliance in it somewhere but I'm not sure exactly where. I feel like maybe the pins at the end where the track is joined to the body of the vehicle need to have some ability to move, maybe vertically like a suspension? Or perhaps you could just print the last segment of the track front and back out of TPU instead? I think the resolution to the jamming might be adding some compliance instead of trying to make the helix perfect.
You are an amazingly creative designer, James.
That's a very nifty drive mechanism that I'd never seen before. Awesome sauce.
You productivity output is astounding.
As for your wire around your mold, metals have spring back and you need to take that into account when bending metals around a form.
Ron Covell has this down to a science.
However, this mechanism is a fantastic idea, I always love seeing your projects.
If you want a tread waving to move forward, you can also use a series of alternating semi-circulaire wheels, or just alternating off centered wheels. Yes those are less cool than a corkscrew drive, but they are way simpler to print, and don't need the hand made screws.
This is such a cool build
A project that most of us can make. Finally.
For great tips on bending metal, I recommend Ron Covell.
In a recent project he describes how to measure your "springback" so that you can calculate the correct size of form to use so that the metal springs back to the size you actually wanted.
He’s an excellent teacher. I love watching his vids.
This is super cool! I will say in my opinion this will be way less efficient than a bare screw on the ground once you account for all the friction in the linkages and inside that track since that screw is now always encountering friction on the inside of that track both top and bottom, but that's what my feeling is. Very nice build love it.
Another really interesting project and awesome music choice!
James' projects are just incredible - kinda the stuff other people would spend a whole mechanical engineering dissertation on or invest money into developing, and James is like "I think I'll try this, today" :D
I love the printing music, it fits your farm oddly well for some reason 😄
My sister came in and expressed interest in this as her first car. I look forward to future updates on your progress on developing the road legal final product.
I love the Mr.Fusion just quietly sitting in the background.
So many machines!
100 percent positive Colin and this guy will build the first ever metal gear
This is such an interesting thing to watch move. Very interesting!
Really pleased to see this mechanism, I do want to ride it!
However to form the steel I would rather have done a 2 point roller pusher at the exit of a wheel feeder. Like : the strait bar of steel is feeding to a first roller bearing that push it to the right et an other one after it is pushing down. With adjustable angle of constraint
I would have just rolled a "spring" around a round mandrel and stretched it.
[edit] naturally I really should watch to the end before commenting. You are right, though, for a large pipe spiral you'd need something similar to a pipe roller, perhaps with the angle of one of the external wheels adjustable.
@@TDOBrandano It can definetely works too, but can be very difficult if the diameter is to important. Spring steel is, by definition, very elastic and can be hard to go on the plastic state
@@badger9641 spring steel is also really hard to work with and James is only recently learning about metal working, would be the best for sure but I doubt he would go that route... he will probably just 3d print a gigantic spring and it'll be awesome😂
@@jonsnothere84 it seems more than accurate ahah
However, metal bending is very cool, and can be a very step forward for designing robot 😁
@@badger9641 yeah I wish JB did more metal work, could really improve the quality of his projects
I’m gonna be waiting to see the better version of this after you spend some time and your skills to make it better.... 😊This is an amazing build
It actually drives a fair bit slower than a "screw tank" would, because the driving force is really only the tilt of the section of foot in contact with the ground. It would drive quicker if the track sections had studs offsetting the contact point from the hinge, but it would also require more power. The other advantage compared to the screw tank is that you can do full differential steering without just rolling sideways.
This would be a fantastic premium RC toy.
This is absolutely whimsical and I want a car with this
I made a metre long "pet"caterpillar that uses this system a couple of years ago, I was wondering when I would see other designers use it. Nice work James 👍
It looks so goofy while driving, I love it.
Great video with an extremely novel drive mechanism! I'm curious if dividing the both tracks into two (for a total of four tracks, two for each side), with every track running 90 degrees out of phase, would help with stabilizing the gait. I wouldn't envy having to design that though!
Always an adventure with your channel.
I am surprised at how well that worked
It looks rediculous.
I love it
Awesome video again man!
I would use spring steel, heat it up, tap it into a mould and once you have the desired shape harden it.
I would scale it up with a huge camshaft drive.
you can't rely on this thin wire design with larges forces.
it twists and bends freely.
I LOVE THIS CHANNEL
My suggestion would be to find an appropriate spring, stretch it if you have to, THEN design the components. This would be much easier than trying to work the other way.
Very nice!
Oh wow caught upload within 1min, cheers from the US fam
I don't know if you have access to a lathe, but there's a very simple process for making rather custom springs, basically a piece of tool steel with a hole the same diameter as your wire. You can use the speeds and feeds to customize the length and width between coils while ensuring they remain coaxial and ascribe a perfect diameter.
I like the video👍. I think that with a bit more modifications you'll be able to make a full-size version of this. Looking forward for the next video
i love your upload schedule
It sounds like you have to get the metal spirals almost perfectly spot-on in order for it to have no issues... which sucks, because unless you can find somewhere that can make perfect spirals everytime, you're always going to end up with some sort of imperfection that can affect the drive...
Overall though, well done!! Fantastic project and an awesome video!!! Thanks for sharing!! 😄😄😄
I highly recommend the video about springs manufacturing at home from This Old Tonny.
He uses a lathe but its possible without it. You are pretty smart.
Just a thought .. When making a bigger version it might be easier to weld together a bunch of elbows or formed bends rather than trying to form a spiral from a straight steel tube.
Considering that you have the tools, you could make the bends yourself. That and welding them back together might be extra work but would surely make it more replicable.
Thanks for all the excellent videos!
Greetings from Maine. One of the first screw-propelled vehicles that was actually built was designed by James and Ira Peavey of Maine.
With all that shaking, a pair of googly eyes on the sides may be a fantastic upgrade.
A low friction bar stopping the top of the track from rising too far might help avoid sagging. So it's a wave constrained between two parallel surfaces (top bar and ground).
this is somehow predestined to be used on water, and must find its way into some kind of amphibious vehicle, or ship, ! Awesome invention!
For the riding wave drive (the wave rider?), you could try using something like a ground anchor used for dog leads, or tents, etc. If you can find something that a large breed dog can't pull out of the ground, it might be heavy duty enough to form some tracks for one end or the other of your vehicle.
For forming the helix around the metal form, I suggest using a metal that work-hardens, like brass. If you heat it with a blowtorch, and then let it cool back to room temperature, it will anneal and you can bend it easily. Then you can easily form it around the plastic helix. Bending it, or tapping on it with a hammer and anvil, will work-harden it, so it becomes much stiffer. If it’s not quite the right shape, you can anneal it and bend it again. I typically get two bends, or five hammer blows, before it stiffens up.
Small brain: snake-tread tank
Big brain: _SNANK_
Truly the most creative and unique designs ❤ frm 🇮🇳 bro ✨
You might be able to make the corkscrew out of tubing, then fill it with expanding foam or some sort of polymer. Once the filling expands and hardens it will be stiffer. I’ve heard of a similar approach being used on small airplanes
Quickest way to make that design work would probably need some king of rail bearing in each linkage in order to carry the screw and help with the stickiness problem that seems to plague the design. This would reduce the need for a perfect screw as well (I think)
Some kind of suspension or pre-tensioning might help a lot, too. To me, it looks like every part of that drive mechanism is fighting with the rest and it really needs something to sort that out.
This guy is so smart its easy to admire him.
This is definitely one of weirdest drive mechanisms I’ve seen. Really interesting.
This has potential to be the new mode of transportation on the Moon and Mars!👍
Super fun idea to explore, great job! Perhaps a single drive belt would be easier to fine tune on the surfboard. Maybe even a contoured shape on the track that would maintain surface contact as you lean the board to turn.
Hmm seem to remember a certain South Park episode lol
you can use teflon for friction
Maybe instead of that coil, you could use a shaft with a series of cams attached.
I think if you accounted for the spring-back of the screws they should match your CAD better. The other thing that could help out is using a 2 part assembly to form the screw, where you have the mandrill with the profile inside and an outer housing that you would rotate around the mandrill to hold the screw in place. Either way, this is a really cool concept and I look forward to what else you do with wave generators for motion.
Merging this idea with a bicycle sounds like a really cool concept (and by merging I mostly just mean having the tracks be pedal driven)
I think you'd eliminate a lot of the jamming if you give your idlers an extra degree of freedom. they seem to want to be able to slide back and forth as well as rotate.
also you might have more luck getting the springs into the right shape if you get them red-hot with a blowtorch first to anneal them and soften the steel so it's more compliant (obviously the form you wrap them around would also need to be metal in that case)
Just a note about the coil form diameter issue in your conclusion. When expanding the spring, you can rotate one end while keeping the other fixed to maintain the desired diameter.
Comercial springs aren't made by winding wire around a mandrel. Wire is fed through a die and strikes an angled anvil that causes it to bend into a spiral. The position and angle of the anvil determine the diameter and lead of the spiral. The anvil's position can vary to make conical springs and multiple anvils allow end loops or hooks, etc to be formed. It would take enormous force to feed thick wire or tubing though.
This method of propulsion has a certain amount of comedy to it😃
I imagine that driving both ends of the helix would keep it in shape, although admittedly that won't help much with your proposed ride on version.
Excellent content btw👍😃
You could easily add some sensors to compensate for the uneven movement so that it tracks straight and compensates how much each track gets driven.
I can't imagine that system ever working very well with more weight since the weight is carried on a spring with no support in the middle. It might work to make the undulation motion of an eel if you wanted to make a swimming robot, but for ground contact I think you'd be better of with something like a crankshaft above the tread with connecting rods going down to the top of the tread.
This would give the sequential up and down motion with a lot of force pushing down. (since the crankshaft would be MUCH stiffer than a spring.
Really like to see this full size
I like this contraption. It has... character! :P
Excellect as always. One suggestion you should incorporate cnc maching where possible for example the large plates could be milled from wood and might make it cheaper and consume less time for people
Distance from top to bottom of the wire slot is to high, it allows {slop} up and down of the feet on the wire, this is disrupting the wave, When the feet are on the ground the wire is in contact with the foot bottom but that means with the slop when they should be lifting it is delayed by amount of distance the curl travels before contacting the upper side, so the wave form is not sinusoidal. Its also introducing side to side torque on the drag links connecting the feet, one side is loose and one being forced up or down, this is adding to the resistance to motion. Seems to me {haven't tried it } that a bearing locked on the wire dropping it's motion down via a connecting rod to a centered foot on a chain might give a bit smoother motion, I know more parts, more precision needed/etc.
Another benefit is that this doesn't tear up the ground quite as much as a screw-tank does, like if Colin wanted to till soil to grow vegetables he could just drive over the area :P
Though a screw-tank has the benefit of being capable of lateral motion. But this is quite cool to watch it move, its like the undulating fin of a Knifefish which can swim backward or forward!
Imagine a rectangular platform with a wave drive on two sides. Now cover the whole thing in fabric and boom! Magic carpet
Imagine, in the midst of a war zone, you see a tank like this-
“Oy, whatthedevil?!?” “Trippin mate…”
suggestion: putting a tire strip of rubber along the bottom to give it more of the snake like quality and at the same time allow it to stand a bit more punishment
A solid shaft with a series of cams that correspond one per track link are fixed such that the highpoints form helices... A lesser amplitude, allowing the links to be narrower, then a frequency (period) in excess of three... To be really ambitious, have 4 tracks arranged as two pairs with the crests and troughs half a period out of sync... this would at once be considerably smoother and afford greatly increased surface friction (grip).
If you have a rotary attachment for your CNC you could cut a groove into a cylindrical piece of wood so you could get a perfect bend that fits your cad model
😂I love your contraptions.
For the screw I wouldn’t use tube, I’d get it made in some thicker spring steel rod, yes it’s gonna be heavier but it should absorb some of the shock from it hitting the ground and will go right back into shape if it has too much weight on it at some point, preventing a need to possibly order a replacement screw in the future if you actually enjoy riding it around
could you use 2 dimensional sine waves offset spinning instead of coils? or use a series of motors pushing the "track" segments down based on digital sine wave provided? if you did the latter you would be able to bypass screw deflection.
James, get some steel pipe, heat your stainless steel rods and then bend them around the pipe. As you indicated the screws are more than likely slightly out of round. Cheers, Great videos.
If you know anybody with any old basic lathe , you can use it to make a wire spiral. A good length 15 feet or longer will make it easier to control, then cut off the excess when your done.
You may get a better corkscrew spiral by forming the wire into a tighter spiral initially and then stretch it out to make the required spiral.
EDIT: Ah you covered this idea at the end of the video.
print a jig to make it...a cylinder you cut the groove in with heavy fill so tuff...to get the size mesure the full up and down of the track subtract the thickness of the bar and vuala ..roll it on the ground to get the twist in it
nice new 3D printing music
Greatly brillant👍🏽 i think it would be very inconfortable for a passenger in real size it’s too shaky😅 but for a all terrain robot it would be great !
10:30... The music matches quite well with the walking actions of this weird thing....😉
I like this method of perambulation. A single motor and steerable seems the way to go.
Appropriate music towards the end - lol.