Teardown of Surgical Robot Instrument

[@JasonHill-g8r]

the cables are actually braided tungsten, and they're stupid expensive (i.e. account for ~50% of the total cost of the device) which is also why they are crimped into tubes for the length of the shaft.

[@martenthornberg275]

What is the advantage of tungsten wire over steel wire?

[@ErtugrulK]

​@@martenthornberg275probably oxidation purposes

[@Sheevlord]

@@martenthornberg275 Apparently tungsten is among the most flexible metals used in mechanical cable constructions. It also has high tensile strength.

[@Bunicutaintelectuala]

Interesting

[@guruxara7994]

@@martenthornberg275 That's an engineering decision, it's probably related to tungsten's fatigue characteristics and tensile strength. Maybe there are alternatives but not as reliable.

[@Jacopski]

I remember seeing this breakthrough in the news thinking how complex it would have to be, years later as an engineer it seems so god damn simple yet still amazing

[@robinxu2009]

if you disassemble a FUJIFILM flexible endoscope, you may find a similar structure which was used for more than 50 years

[@beak90sfx]

I believe the main difference between these devices and endoscopes is that endoscopes do not have a wrist mechanism. The wrist is the most challenging part of the mechanism since the cables need to make a bend around a very small radius.

[@akaHarvesteR]

These look like they would be really great for DIY use, especially for those projects where you have to do things in spaces that are too small to use fingers... They're the ultimate tweezers. I'm going to see if I can find a set. I'm thinking it might just be possible to create a wrist mounted contraption to actuate it using some sort of joystick control

[@NonEuclideanTacoCannon]

It just occurred to me, it might be an engaging project to pick up some of the used instruments, and build an entirely mechanical control system. Clockwork surgery machine. I messed with an optometry machine at a surplus junk store one time, the lens part that points at your eye had 4 degrees of motion, controlled mechanically with a joy stick knob thing. It was so smooth, effortless and granular. Maybe a foot pedal with a fly wheel like an old sewing machine for rotational power for saw attachments or whatever.

[@notamouse5630]

Precision comes from several things: 1) Good enough mechanical clearances on the joints, precision machining. 2) The right counter-tension for each DOF cable, plastic parts are excellent at applying gentle tension to other parts, plastic or otherwise. 3) The very stiff carbon fiber rod would eliminate most of the Coefficient of thermal expansion by matching the steel in the rest of the instrument and avoid any effects of bending on the cables to the DOFs. Excellent, amazing engineering. It appears that the coupling between axes is deliberate because it allows for counter-tension with less wires as only the wrist bend axis has 1 cable for itself and uses coupled cables from the gripper for counter-tension, whereas each gripper seems to have a counter-tension cable and thus the whole thing can be fully constrained to any set of rotations with less cables.

[@theostfrancis629]

Awesome video, thanks so much for sharing! As a mechanical engineer I appreciate your attention to detail.

[@Pillowcase]

14:38 - I'd imagine the washers are there to account for the unpredictable geometry of the swaged/riveted end of the shaft. If that wasn't there, when the shaft is squished to form the end, there'd be uneven forces on the inner bearing race - so instead of that, the washer sort of takes up those forces.

[@ut4321]

The swaged shaft seems surprisingly low quality compared with the relatively precise manufacturing and parts choices for the rest of the device.

[@aaronh1372]

Pillowcase, my thoughts exactly

[@Pillowcase]

14:38 - I'd imagine the washers are there to account for the unpredictable geometry of the swaged/riveted end of the shaft. If that wasn't there, when the shaft is squished, there'd be uneven forces on the inner bearing race - instead the washer sort of takes up those forces.

[@UQRXD]

Reminded me of the old dentist drills with pullys and belts.

[@Pillowcase]

It's fascinating to see how a spectrum of manufacturing techniques and design philosophies combine in one product. The injection molded casing with clips would be at home in the most common commodity device - along side high precision clockwork mechanics that could be in an aerospace instrument.

[@benhatcher2603]

Are you sure that the inner tubes are for cleaning and not irrigation and/or suction while the device is in use?

[@KallePihlajasaari]

I doubt suction but irrigation or insuflation are my guess to prevent body fluids from trying to travel up the tube.. Obviously flushing tissue for cleaning purposes is also required so I expect that it will serve multiple purposes.

[@Everfalling]

This was a fantastic breakdown and resource. Thank you so much for being as thorough as you were either showing all the motion and cable routing.

[@Skinnamarink.]

You've done the internet a great service. We appreciate you.

[@tomassmith5461]

Would you like to come to the factory and view the assembly process?

[@KallePihlajasaari]

A follow-up video of this would be awesome. I imagine assembly will be rather tricky without the require jigs. If you can make such a visit possible I hope you will try and reach out to him again, he may nothave seen your comment.

[@vishalramadoss668]

This is an excellent video showing the intricate design of the mechanism and lucid explanation

[@4dogsgaming]

I've had two major surgeries with the Da Vinci robot.

[@PhilGregoryFX]

Brilliant! Thank you for posting this, as it solves many of the design problems I encountered in a kind of unrealted area ( puppetery and miniture film sets ) that I thought could not be solved effectively, without using electronics. However, your video has given me confidence that the same design problems can be solved sufficiently well, using just mechanical methods. Cheers :-)

[@nathanielvanrumpt4126]

Fascinating device! And love your video style. Please make more!

[@ransombot]

The washer on the swaging is probably to protect the barring. If you bottom out during manufacture it's better to hit a non critical part than a barring. If you bend any part of the barring you will cause binding and other undesirable and inconsistent when moving. I'm sure it's to get closer to a 100% reproducible with manufacturing defects minimized. Also probably protects the barring as it's non sealed from abrading the swaging and putting particulate into the raceway.

[@greanhare5270]

Considering what these tools do, they're surprisingly simple. Not including the computer and the motors, these tools would be totally plausible over 100 years ago.

[@stevewalston7089]

Just finding this now old video ... thanks for doing this though, great tear-down for sure. Two things to comment on, the washers backing the flared end are surely not an afterthought but typical to help even the forces out when using this sort of cost-effective jointing. The second is you really shouldn't use electronics nippers on anything but soft copper wire. Cutting cable will surely ruin them and leave dent in the cutting surfaces. Use other cutters designed to cut cables and hard wire as they typically gather them in triangular jaws to prevent them from being squeezed out.

[@lukeshoff3983]

I had to pull some cables from a very small hole in a building, this would have been the perfect tool for that.

[@christiansprojects-cgmanuf1426]

I own a pair of biopsy forceps pliers I once got for free. It's one of the most useful tools I have for jobs just like the one you described.

[@mglenadel]

The electrical contacts can also be used in some other type of tools to cauterize/ablate (burn away) tissue.

[@chongsiu7893]

This is great, what a cool mechanism! Thank you very much for sharing.

[@jungleb]

Your work is amazing! Incredible research and knowledge!

[@FLORIDIANMILLIONAIRE]

I have like 50 different ways i can make the end effector much smaller this is not a great design but thanks for opening it up

[@phonophilia9095]

great video! I imagine the coupled axes are perhaps uncoupled using software

[@CarsonCannon-y5u]

do they have any in a stabilized ambulance portable one with a database of all known surgeries and vr practice runs??

[@aaronrowepalmer]

Great educational video, the world can benefit from this knowledge in many non-medical ways!

[@dbogdanovicsr]

Nurse: Sir, we got a patient, unconscious. Kyle: Get me the drill, 10mm, sds+ Nurse: But sir? Kyle: No questions, we got a life to save.

[@PacoOtis]

Excellently presented! Thanks for sharing and the best of luck!

[@ericlotze7724]

I wonder why they are disposable? Granted strict medical standards, and maybe the thermal cycling of the plastics / metals (especially the cables?) ? Even then i would assume refurbishable would be a good option. Maybe some right-to-repair stuff... Either way this was really neat, and thanks for the overview/teardown! (Now i want to go make some contraption using a pile of these used ones lol)

[@tomvandebroek2203]

Strictly business-plan related. Think of your Gilette razors or your Nespresso pods. That is were really income comes from.

[@nibblernibbles3205]

I'm with you for many consumer goods, but having seen the details in this great video, I think it's reasonable that these are dispoable. Issues that would be reasonably expected to occur after multiple uses: ageing of plastics due to autoclaving; corrosion as seen due to dissimilar materials; fatigue of the cables due to small bend radii; wear and buildup of wear particles in guides, pulleys and drive cogs etc. Which might lead to sticking, slack, loss of tension, loss of joint stiffness, backlash, affecting quality of the control which might interfere with the movements causing poor outcome for the patient. Then there's buildup of organic material in gaps and small spaces. Worst case is seizure or snapping of cables during operation which could be catastrophic at a critical moment, or lethal infection. Think about the cost of the operating theatre, medical staff, equipment and consumables and it's probably a relatively small additional cost for the quality assurance and reduced risk to patients, and reduced liability for the manufacturer... who ultimately needs to stand behind their warranty by taking care of these issues somehow. Uncscrupulous users in poorly regulated countries, perhaps using secondhand parts, might harm patients and the reputation of their brand so it's fair for them to enforce using a memory chip.

[@Spookieham]

Sterilisation and autoclaving can't be done forever as it may degrade the internals. Plus if you keep cleaning after its used you increase the risk of contamination building up somewhere to a point it poses a risk.

[@samcoupland]

Having worked on surgical robot end effectors, just some of the reasons for them being disposable; 1) Contamination, autoclaving doesnt remove all tissue contamination, (its sterile, but still dead meat), 2) Corrosion, autoclaving is the quick way to rust even surgical stainless steels 3) Fatigue, the cables are bent around very tight radii repeatedly and start to fail (fray) after low 10s of hours use. 4) Calibration, with use, corrosion, fatigue, the parts loose tolerancing and become looser and harder or impossible to control accurately. To referbish to the correct standard isn't really cost effective, as the bearings, cables, tubes, at the very least would all need replaceing, and most of the tool is riveted or crimped together both due to scale (no room for screwed fasteners) and reliablity (really don't want loose screws falling off inside the patient), in a way which would mean having to destroy many parts to recover a few, which would then need refebishment and extensive cleaning to be reused.

[@ericlotze7724]

@@samcoupland makes sense. Thanks for sharing your expertise!

[@mrb9474]

love the close up shots!

[@shanepython]

Very, very cool and informative. Great video!

[@Tadesan]

It could be that the monetary value of this surgery being minimaly invasive buys all these tools. Steel rods dont harbor bacteria like cables do

[@theGoogol]

So no rotational degree of freedom? Only in/out/up/down/left/right?

[@Sykotik_]

Rather perplexed by the use of ball bearings in a low-use disposal piece. Would have imagined some sort of bronze sintered bushing would be more cost effective.

[@beak90sfx]

Stiction (static friction) has to be reduced as much as possible to get smooth motion. There’s a lot of tension on the cables, which is transferred to the bearings. That would result in a lot of stiction with bushings. The newest instruments still use ball bearings, so I imagine they could not figure out how to maintain good performance with bushings.

[@DoRC]

Do you know how much one of these cost new?

[@shadowaries1516]

Wonder what surgerys those tools preformed before ending up with you 😂. Couldve just disassembled a legendary heart dr robot.

[@dhanvindhsoundar5707]

@12:19 you mentioned there were two separate cables, how are they crimped at the wrist end and how is it tensioned there?

[@snik2pl]

Is it possible cable goes in one peace inside steel rod and is additionaly crimped at ends of rod.

[@lumotroph]

Holy shit what an incredible design!

[@howtosketch1745]

At 7:55 you talk about the coupling between the two axes - does this mean it is not possible to use both joints simultaneously? For example, if you try to pinch the jaws while tilting the wrist angle, will you get slack or bunching of the cable? How do you make both joints independent of each other? Also, amazing video quality!

[@nicholasweiss4662]

I think this is on the operators end to accomodate. I guess the driving servos can apply tension to the tools, for example to pinch stuff. Then when you move the "wrist" of the tool the operator can compensate the unwanted movement of the pliers to keep them pointed where they want. I dont know if this analogy helps, but in construction excavators, when you want to move the bucket parallel to the ground, the angle of it changes as it travels. This then has to be compensated by the operator by turning the bucket in the opposite direction. More advanced excavators can do this compensation automatically but i dont know if the davinci robot has an automatic compensation system as well.

[@bmxscape]

this is handled by the computer controlling the servos, in the same way everything needs to be compensated when the whole 7 axis arm moves. every bit of the arm can move at once and the jaw can stay steadily in place. its called inverse kinematics

[@dexio85]

Very informative! Thanks for the teardown

[@Cknight700]

Can it do surgery on a grape though

[@gerryk101]

Someone should upscale this model to a robotic hand and have it function to brain signal response from an EEG head band

[@cipedead0777]

Been looking for years for these. I must be looking for the wrong name. Have you got any tips on what to look for to bye some please? Thank you.

[@beak90sfx]

Just search for Intuitive Surgical on eBay

[@cipedead0777]

@@beak90sfx thank you I will try this.

[@budstep7361]

Nice video! Novel and information, thank you for sharing 😁

[@NickoSwimmer]

Cool teardown! Your estimations were quite accurate! 😉

[@PiyushSharma-iu3bd]

How do you define the relationship between coupling axes , pitch and yaw ?

[@beak90sfx]

Determining the coupling between the axes might be somewhat complex. Not sure exactly how you would go about that. The forward kinematic coupling is probably not too challenging. The inverse kinematics might not have a simple solution and might need to be solved with numerical methods.

[@asakayosapro]

These things are usually operated by servo motors, which know whatever angle every axis is at all times. The surgery probably involves endoscopes as well so they can see what they are doing. The servos convert human legible commands (turn, grab, twist, etc.) into instructions or gcode for the servos to do, and do exactly. If one were to convert this into some manual grabber for getting your keys out of the grilled drainage….yeah, that’s going to be a quite an endeavor.

[@danbrit9848]

i want one ...as a 3rd hands for pcb work

[@roboticsengineering.kanwal]

Hello sir, thanks for sharing very informative video i have ever seen. I am a Postgraduate robotics engineering student ... I want to learn more about surgical robotics arm and endefectors .. can you give me your valuable advice from where should i get study material about surgical robotics arm mechanism. If possible kindly share some link on same topics on which you posted video.

[@neozhou837]

Brilliant sharing! Is the coupling of the 2 axes compensated by software?

[@LimabeanStudios]

My brother is a surgeon I gotta get one of these from him

[@mickflury]

how often do the cables and pulleys get caught in tissue or is that an uncommon issue?

[@viniciusnoyoutube]

Awesome video.

[@stefanguiton]

Excellent video!

[@svenfritsch9702]

Excellent vid!

[@jasonstatement3553]

Awesome video, thank you for the teardown!

[@polka23dot70]

It looks like something that was made a century ago.

[@darktherapy]

22 inches long, 8mm diameter. Choose a measurement scale 🤣

[@KallePihlajasaari]

Hmm, I like the fact that mixing units is sometimes appropriate at the human level. Obviously it requires mono unit system people to spend the few CPU cycles to convert but I had no issue with it even though I have lived in metric cultures all my life.

[@shockingguy]

Ha ha ha this is very cool, now what am I gonna do with one of these when I buy it because that’s what I’m already thinking ha ha ha curse you ha ha ha ha ha ha ha

[@williamglenn9885]

Where are you from? California?

[@mandcali7613]

Nice. Thanks. You’ve earned my sub for posting a video like this… keep it up!

[@JAALMARZA]

Great video, thanks for sharing 👍🏼

[@Duraltia]

The whole coupled motion seems to be a royal pain in the ass to manually deal with as an operator 🤔 Here's to hoping the System has an automated Kinematics System accounting and compensating for that 🤨

[@FLOWRIDER0_]

I got to try one out at a job fair, they do, or at least the one I tried out did

[@RaulVillaseca]

Gracias por su video, me suscribo a su canal. RVC Lima Peru

[@UQRXD]

Robot arms and legs. You cant tell them from real people now days.

[@DIfromTCS]

THANKS SUPER HELPFULL

[@dvi3660]

very helpful

[@user-sh4zq4ge1o]

It would be cool if you could show some more details on how the two-part pullies are tensioned against each other. Is the mechanism similar to those antibacklash gears which have springs embedded in them?

[@beak90sfx]

There actually isn’t anything else in the mechanism. There’s no springs keeping the tension. The pulleys are both rigidly attached to the shaft, and the cable itself acts as a spring to keep it tensioned. I imagine they have some sort of jig to apply the right amount of tension by twisting the pulleys in opposite directions, and then the pulleys get tightened onto the shaft, locking the tension in.

[@davepreiss]

Great video and insights!

[@Pillowcase]

I wish there was something in the frame to show scale - like the tip of a ballpoint pen. It's easy to lose reference to how small the unit is, especially with such clear macro photography :)

[@lut.2500]

Awesome!

[@mohammadkhoobani9439]

Thank you. Is there any portion calculations for desiging pullies? I mean: if u try to move the end-effector and rotate only in x direction, is there any rotations for y too? Even if the operator dont use the y joystick

[@roboticsengineering.kanwal]

Awesome

[@schto173]

actually quite a scam with the memory chip... Pretty sure these devices could be used hundreds of times. if not for this chip :( how silly....

[@TeamGeeseteeth]

About the size of a dime*. ;)

[@ViniciusMiguel1988]

This could easily be made to last 100 uses. Very wasteful design

[@BGraves]

Please demonstrate that. The risk of any material failure is high, so you better be right.

[@picoj44]

The economics will balance either way so I’m not sure it ultimately matters how many uses it has.

[@emilien.breton]

Couldn't agree more. Through that little chip, the company is creating a monoply on selling the disposable grippers. They convince hospitals to buy their robot arm and then they sell the disposable grippers for whatever price they wish. Exactly the same nonesense as printer ink cartridges. Edit: I've been watching the video again and am in awe at how different our world views are. "Protecting users against knockoffs" I call "anticompetitive practices". "The next incredible feature, which is that these are entirely disposable" I call "programmed obsolescence". "The materials have to be cheap enough so Intuitive can make a profit" is irrelevant because they've created a monopoly and can sell the grippers for whatever they wish. "The hospital doesn't want to spend too much money on them" is irrelevant because without the grippers the robot arm becomes a (ridiculously expensive) paperweight. To my ears this is insanity; alarm bells going off in my head the whole way through. To people here, this all seems routine. Crazy how different the world is, out there.

[@DigiLab360]

Exactly! They can build a plane that flies a million miles between service intervals while transporting thousands of passengers at 30,000 feet, yet these only last for 10 uses in an operating room?

[@BGraves]

@@DigiLab360 this is capitalism. If Boeing could design replaceable wings, they would

[@Brysey19]

The cables / wire ropes are titanium. I imagine they were quite tough to cut.

[@virhilo]

Titanium is relatively soft metal compared to steel, it has less than half of tensile strength of steel.

[@beak90sfx]

I found out after making the video that the cables are tungsten, due to its very high strength and long fatigue life.

[@shamancredible8632]

Horrifying

[@banamali143]

Wowww👍

[@1480-b5g]

Are pulleys really more accurate than gears?? Well, i guess its cheaper, and way easier to manufacture for sure.

[@robob4465]

That black tube sees to be so long,that you'd probably need tons of gears for the whole length,so a couple of little cables make sense

[@beak90sfx]

Many small gears over that length would result in significant backlash, reducing the amount of control the surgeon has. However, newer instruments did switch to gears for the rotation of the shaft, since only 1 or 2 gears are needed.