Tunable Stiffness Compliant Mechanism with Bistable Switch - Binary Stiffness (Part 3)
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- Опубліковано 17 тра 2022
- This video depicts a translational binary stiffness compliant mechanism that achieves two different states of stiffness by being triggered using a simple bistable switch. One state is very compliant while the other state is very stiff. The mechanism was designed by Reinier Kuppens while working in my lab at UCLA as a visiting scholar from Delft University.
Further details about the mechanism are published in the Journal of Mechanisms and Robotics, and can be found at this link:
asmedigitalcollection.asme.or...
A raw video of this mechanism was previously uploaded to Reinier’s UA-cam channel:
• Fully compliant static...
but this video is intended to explain the mechanical principles behind how the mechanism works. This video is the third part of a five-part mini-series about binary-stiffness compliant mechanisms. Be sure to watch the other parts to learn more about how they work and for what applications they could be used.
The part files for this mechanism can be downloaded from Thingiverse at this link:
www.thingiverse.com/thing:543...
Also, to understand more about compliant mechanisms in general, be sure to watch the other videos in my Compliant Mechanism Design series on this channel.
Acknowledgements:
This video would not have been possible without the brilliance of Reinier Kuppens, Just Herder, and Miguel Bessa, so a huge thanks to them.
Donate to help support my channel:
If you’d like to make a one-time donation, you can use the following link:
PayPal.me/FACTsMechDesign
Thank you for your support! It is much appreciated and helps enable me to make more content.
Disclaimer:
Responsibility for the content of this video is my own. The University of California, Los Angeles is not involved with this channel nor does it endorse its content.
My dear son, I love hearing your delightful voice narrating genius videos like this!
Yeah mom, he's doing a good job.
Son to be proud of :)
Who is this? Am I just dumb?
that's cute
Awww such a wholesome comment :)
I recently repaired a Willomore seismometer that uses this principle to almost completely eliminate the stiffness of the springs that suspend the weight.
There is almost no force returning the weight to centre when it is properly tuned so it's resonant frequency can be less than 0.1Hz, to pick up those really slow earthquakes.
These kind of mechanisms will bring a revolution in our technologies.
Keep it up.
Hey Jonathan! I had "followed" your work for a long while, but just found this channel today!
Nice to see you making this interesting work both accessible and understandable, on this platform.
I have often seen designs in industry, using "classical" bearings and sliding mechanisms, that could really have benefited from proper application of flexure-based designs... Hope that you're keeping well, and that life is treating you well!
Jonathan, I love your videos! It appears to be taking off like wildfire. Congratulations!
I'm entering my first year of college as a mechanical engineering major; it's videos like these that inspire me to design my own mechanisms and pursue the oddities of classical mechanics! Thank you!
Nice! I'm planning on going to college for mechanical engineering as well!
@@alextheferret5674 let's go guys! It will be cool. I'm near to finish my studies as a mechanical engineer :)
I love learning, and with your channel, I am never disappointed. Thank you! Happy New Year!
Congratulations for your success in this project. As always it's amazing to watch your innovative projects
The pacing of the explanation is perfect. Well done!
I've seen compliant deformation mechanisms before, but this one finally explains the concept, and now I really want to find a way to implement it in a practical application...
oh wow this actually went from utterly inscrutable to obvious after that explanation, that's impressive!
This is very cool, thanks for sharing and for the detailed and accessible explanation!
I hope to come up with a project to use this soon. Very cool. Thanks for this series
Super amazing and cleverly explained!
Great presentation and animations.
Excellent explanation, thanks!
no idea why this showed up in my feed, but very cool nonetheless. I couldn't figure out why you'd want something like this until the end where you showed the "self-switching" ability of the device. Then it 'clicked' for me!
Those are such interesting principles !
Great video. I've had some interest in compliant mechanisms since I was first sold the concept, maybe it'll be useful one day.
It is impressive.
Thanks again for a great video 😊😇
Cheers
amazing explanation
incredibly intresting video
I'm glad youtube decided that THIS was was something I needed to watch haha.
This is amazing
why am i here, when did i get here, i have never once over the course of my entire life sought out mechanical design or the application of stiff and non stiff mechanisms, but i watched, i understood, and i was intrigued the whole time.
Do you have any guides for how to design/model your own flexure mechanisms in e.g. Solidworks or other CAD software? Very cool video/paper, thanks!
Just the best in youtube
Thats insanly cool
amazing!
This is fantastic thank you, and i suspect working through the material you have made available is going to have a big impact on me.
I wonder if you could kindly let us know which plastic are you using for the demonstration mechanisms please?
Wow. Very cool.
This is really interesting idea!
It might realise “physical computer” as I have seen a computer by using water flow. Computers without electron excite me.
It seems these could be used in a way analogous to a resettable mechanical fuse.
That plot at 1:14 is similar to a Zener Diode. Current is the Y axis and voltage is the X axis. When a Zener Diode is reversed biased, at certain point in voltage it will remain constant over a various change in current (the left knee in the graph - the Zener point). That is how Zener Diodes regulate voltage.
that looks awfully like a zener diode plot. I bet you could set it up with a damper on the force input to make a easy force regulator
Anytime I have a system that needs stiffness cancellation, I just think about baseball or my grandma. Works every time!
whenever a video starts with "This..." I can only think of Doug
The application I thought of first: a vehicle suspension with a stiff on-road mode and a soft off-road mode. There are other ways to accomplish this (pneumatics, hydraulics, electromechanics), but this mechanism could probably build a two-mode suspension with just springs and shock absorbers.
I like this idea. Instead of a dovetailed bar you could insert an elliptical dial and fluently change characteristics.
Hello, I wanted to ask what song/track you used during this video? I really like it. :)
Do you have these somewhere in STLs? I would love to print them and play
My mind immediately went to a failsafe mechanism or perhaps even a prop-knife. Producing a compliant mechanism that allows the blade to appear rigid until enough force is applied- at which point the bistable mechanism causes the blade to retract freely could be incredibly useful.
Not sure about need of this in knife, maybe some type, but if you apply a lot of force, you may use your finger on side of the blade to stabilise it, and then it could slice you if your grip extends to the edge a bit
Didnt think this would make me go "thats so cool!!" but it did
This is the future
Make it a few nanometers.
@@dubsar it can be made a few nanometers. Compliant mechanisms can be crafted onto microchips.
Looks like something that could be used for a valve, perhaps inside a dampener?
Love the concept! Can you plz upload the .stl Thank you
ahhh yes. I'm back in the weirdly specific part of the youtube recommendations again
I saw a video, and it demonstrated a device that used flexures to create a linear motion in just one direction and was constrained in that one direction. It was not possible for movement in other directions. It had two pairs of flexures, one pair to an anchor point, and two to the moving part with a third point connecting the free end of the flexure pairs. At rest, all flexures were parallel.
If this rings any bells, I'd love the name of this mechanism. I've been searching UA-cam for the video and going through my history with no success. Any help would be greatly appreciated!
That kind of flexture might be called a "linear stage". You might like a video on Dan Gelbart's channel "Building Prototypes Dan Gelbart part 10 of 18 Flexures".
@@Graham_Wideman Thank you so much. I'm slowly chipping away at watching all the videos on your channel. They are very inspiring. I have a project that requires linear motion in a single direction only, and that can keep it rigidly constraining it in just one direction. Space constraints are an issue and the traditional technique for this particular problem are not possible. Your videos are inspiring me to think in new ways, to contemplate nontraditional,novel solutions and to build mechanisms myself. (using my laser cutter) thanks for these videos!
@@ubza1234 It's not my channel. I'm just an interested viewer and commenter :-)
@@Graham_Wideman Oh 😂 well, It's nice to know that there are people in this community who want to help each other. Thanks for the help!
@@ubza1234 You're welcome! - I think it's cool that others share an interest in these videos, and intriguing mechanisms!
I love mechanisms like this. The yet overviewable complexity for even simple behaviours is a special kind if aesthetic.
But there's a question always on my mind when I watch videos like this one:
Doesn't the material get tired over time? I imagine it would either adjust to the forces applying when idle or simply break, no matter how frequently the product is used.
So how long is such a mechanism functional? Or are my assumptions wrong and it will never break without outside force?
This looks really cool. I'm just very confused about what you could use something like this for.
I would love to see the kind of performance that you could get out of these mechanisms cut out of steel. I think it would not be difficult with jet or laser cutting.
It is possible to 3D print with certain metals as well
'Tunable' seems a bit misleading, as it implies you can tune the mechanism, such as tuning an instrument. What's shown here is still just a binary, otherwise untunable, switch with some extra pieces on it. One would expect a 'tunable' mechanism to be able to be somewhat precisely manipulated until an optimal point is reached, again like tuning an instrument, or using a potentiometer in a circuit to achieve a required voltage, a dimmer on a light switch to achieve a preferred brightness, etc. Though, I can see how you wouldn't be able to do this with a singular compliant mechanism, at least not with one that's simplistic in design.
would "switchable" be a better word than tunable then?
@@radadadadee Yes, because that's literally what this is, a binary switch. Similarly, having a third position would be a trinary switch, and still not a tunable mechanism.
A mechanism isn't tunable until there's fine control of what you're tuning. Problem with this is that typically it would require a secondary non-compliant part within an assembly with the compliant part, such as using a screw to adjust tension or stiffness. There's also the possibility of using multiple switches in steps, or having a compliant stepped mechanism to act as a multi-position switch, but the difference between the discrete steps needs to be fine enough to emulate what a proper tuning mechanism could do, otherwise it's just a n-position switch. There's the possibility of using something like a watch spring with a locking button to adjust tension with a positionable part, but then reliability and holding strength of the button, which then becomes complex in it's own way based on other requirements; there's also complexity in manufacturing here, as you now have a compliant button on a plane perpendicular to the spring's pivot, of which is also perpendicular to the mechanism's range of movement, and that's just for a one degree of freedom mechanism. A truly tunable compliant mechanism is so much more complex than a binary switch, and this is before getting into the complexities of how the flexures behave under varied amounts of tension, one could very easily buckle incorrectly and ruin the intended outcome of the mechanism.
I can see this being used as the hinges for self-leveling lasers.
"Principals of stiffness cancelation"...need to remember this for my wife...
do you think enough of your designs exist now to train an ai model to make these when given certain input parameters(linear translation with x force, rotation about point y, etc)? ive seen some things around about algorithmic optimisation, are we at fully generated designs yet?
Would like to see real world examples of how this system is used.
Usually, bendy things wear out from fatigue. I'm guessing something about the materials and/or design here prevents wear? How, and how many cycles can be expected? Super cool mechanism!
I think that the plastic these are made from is just good enough for a prototype, and the final product would likely best highly elastic metal such as inconel
Im no engineer, but to my limited knowledge there would probably be a significant difference in wear between flexing and bending. as such, it could probably be designed so that it would more than outlast its intended lifespan
I just don't get it. I wanted to make a compliant based fan with "wings" and I don't understand what I would need to do
Are any of these compliant designs available for download so I could print them?
This would be a good switch for an airbag deployment system.
Can these mechanisms be used in MEMS devices ? To cunstruct micro mechanical structures.
Absolutely!
this was recommended to me by youtube randomly.
it sounds interesting but i have no idea what it is for or where it would be used.
would someone be so kind and brefly explain where thoes Bistable Switch could have a use, without getting too much into details?
please and thank you
You should make one using truck leaf springs!
basically the stiffness is capped to the stiffness of the bistable compliant, then it turns to 0 when the bistable is off.
The value of the stiffness of this machine equals the stiffness of the bistable till reset??
Ps. the reset can be a lever blocking the bistable on his free axis, but you need to apply the same force needed to "unlock" it, am i right?
so the diaphragm plate in a clutch?
The tensegrity table is a similar principle? Of course, without the switch.
What's the practical use of this?
More than understanding is what is the practical use for any of these mechanisms?
I just repaired an old Willmore seismometer that uses stiffness cancellation like this to tune out the stiffness of the main spring and the flexures that holds the weight. That lets it tune the oscillation frequency down below 0.1Hz for picking up those really slow earth movements.
Flexures in general are not at all common, but in the areas they are useful they they tend to be by far the best solution.
Very interesting, have there been any practical applications proposed for this mechanism?
Been wondering the same. It would have been a nice addition to the video
I recall seeing something similar some time ago, which was submitted as part of the trigger for nuclear weapons.
This is very interesting technology. What is a practical application of this technology? Where might we see this technology implemented?
For those wondering, this is called the "price of bread test". IE what does all this have to do with the price of bread.
Fascinating, but what is the use for this?
Really neat that I didn't understand a single word in this title
I misread the title as "turntables" and thought "well, how TF is this gonna work in a turntables?"
What material is it? The flexibility unbreakable? A metal coated plastic? Like mini snake robot?
At 3min 29s issit like a release to Jump a robot? The leg to be able to jump, then pull to reset(ready to jump)?
At around*
The producers might like my video on a related method. It uses my variation of Euler’s contain column theory.
ua-cam.com/video/wrBsqiE0vG4/v-deo.html
Here I was under the impression stiffness cancellation involved thinking about math and baseball.
UA-cam's algorithms rightly assumed that this would trigger some sort of kink in me. I find this very erotic. Thanks, UA-cam!
0:48 me (Electronics Engineer): Hmm... zener diode V-I characteristics
One word. STIFFNESS.
Sir, my qualifications are in software engineering, I came upon this by mere coincidence
What is the purpose of this? I understand how it works just fine from your explanation. My only question is "Why is this useful?"
holy shtt
this is basically an extension of mems
Cherry MX compliant when
hø hø... Stiffness...
Short bar, Long bar. Eazy Peezy!!! 😢😮😅
My Ex is an expert in stiffness cancelation.
Can’t you just SEE how it works? It’s like those “floating” tables. It’s cool but obvious if you look at it.
🐝💤💥❤💫👍
I don’t need sleep
Once I hit 50, I need all the stiffness I can get...
The narrator's voice sounds like David Foley.
You said stiffness
Stoked to see these kinds of designs inevitably swallowed up by Capitalism and used to fight the Corporate Wars in 2037
This design seems flawed. A sufficiently powerful force could switch it to it's compliant state if the input were forced over the switches tripping point. I think it would need to be redesigned so that the switch could be independent of the input
I had the same thought
was this not intentional? it seemed the middle portion was designed to toggle when sufficient force was put upon the input
@@ciarangale4738 It's implied that the input will not move until a toggle happens. If that can be overridden, then the design fails.
@@Mecryte What of the demonstration to the right hand side of the screen at 3:30 ?
@@ciarangale4738 Somehow, I missed that.
My ex-wife gives me serious stiffness cancellation.
Mechanical digital computer made out of flextures, anyone?
Not sure how i got here…
BTW, I comment on UA-cam with a pseudonym, so you would not, sadly, recognise me from emails in our history ;-)
Ну и нахера мне это ютуб предложил? Что это ХЗ может вообще? Где применение?
Is there some kind of Video Making Instruction book somewhere that says "All engineering interest videos MUST have an extremely annoyingly and overly loud background music track" ? - It made this unwatchable for me hence a solid 'dislike'.
So this is how erection works... 🤔🤔🤔
Sorry😂🙏
I'll see myself out...