What is the advantage of tungsten wire over steel wire?

​@@martenthornberg275probably oxidation purposes

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

Interesting

@@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.

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.

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

Pillowcase, my thoughts exactly

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.

First someone has to make new tool heads for that to even matter, based on a variety of issues these tools likely can't be used much longer then the 10 they are rated for, from the video it's already corroding a fair bit after 10 uses, and from some of the close ups it already seems to be causing some wear to the to the cable guides in the tube from the particles show on the cable when moving and the fact the metal cables will by necessity have a short lifespan from bending fatigue, Add in that the avg robot surgery cost 20,000 and tools avg 6000$ of that and the robotic tools only account 1800 of that 6000 it's small change in the grand scheme of the total surgery cost, hospitals aren't going to use an unapproved third party tool manufacturer when they're likely to be sued in the case that anything goes wrong and they basically can't be approved by the government for use in the surgery in first place

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.

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.

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.

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

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.

Just search for Intuitive Surgical on eBay

@@beak90sfx thank you I will try this.

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

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.

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.

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.

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

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.

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.

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.

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

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.

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

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

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

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

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.

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?

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

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

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.