Cable lacing on the Curiosity rover

by gameshot911 • 14 years ago

250 70 14 years ago

ktizo7• 14 years ago

I love the fact that there are people, who when faced with photographs sent from a robot on mars, will crop out all the bits of image with mars in them, so they can get a better look at the knots used to tie all the cables down. They must have absolutely immaculate sock drawers.

dfc• 14 years ago

Or they just really like knots. Why do you think that an interest in knots means that someone is going to be OCD about everything else in their life?

Different people like different things. Just because they geek out on something different from what you geek out on does not make them abnormal.

ktizo7• 14 years ago

I was being nice. I genuinely do love them for this and I found it really interesting. I am also allowed to find it funny though. And I am sorry for stereotyping an entire group so lazily. I am sure that many of them actually have really messy sock drawers, if only in the hope of waking up to a really interesting variety of knot.

zerostar07• 14 years ago

Can't blame them. So far it's just rocks.

VLM• 14 years ago

Its hacker news, not daytime television. We don't have to pretend to be boring middle of the road when talking to each other.

What I find fascinating about this story is I've seen much larger and much more elaborate cable lacing jobs that look just as good at telco central offices and data centers, but its always very vague about what exact part of my NDA or employment agreement I'd be violating by posting (or taking, or distributing) pictures. These mars pictures, cropped, may be the only chance for a civilian non-employee to ever legally see professionally done cable lacing, weird but true. There's a zillion other places to see the surface of mars, but only a few to see cable lacing.

Its interesting that in advertising pictures they always use superglue to make the cables look "PHB-good". So you can't see cable lacing in ads, which is too bad.

Done correctly, cable lacing is, literally, an art form. One guy I worked with "knitted" geometric patterns as he spaced the lacing in various locations and used different colors. Also I saw at least one large example of AT+T being "dot matrixed" into a large bundle of cables by careful spacing of lacing.

Artistic cable lacing is kind of an "apprentice" masterpiece situation, you learn lacing well enough to do art, then you show it to other techs (and your boss) to prove you're not an apprentice anymore, then, sadly, for most techs, no more lacing art work. Oh well.

mlni• 14 years ago

Well, there's always http://www.reddit.com/r/cableporn

quux• 14 years ago

I zoomed in on the cable lacing, and my sock drawer is a disaster.

ktizo7• 14 years ago

I found it fascinating, and I have a randomly sorted bag of nearly identical black socks at the moment as I find it easier than bothering with the whole draw and sorting thing.

flatline35• 14 years ago

Your backhanded compliment is a bit disturbing for being the top comment. I've largely dismissed the complaints about the HN community becoming more negative, largely thinking that mature realism was being mistaken for unwarranted negativity.

However, this comment, along with the negative comments about the uptime of Tindie's blog (http://news.ycombinator.com/item?id=4472348), has me thinking that these complaints of undue negativity are justified.

I find the attention to detail involved in selecting knots to be a tremendously interesting aspect of sending a physical vehicle to mars, and I find it to be a testament to human specialization and intelligence that there's a whole community of knot experts that can provide so much insight into the knot choices. Implying some sort of OCD around sock drawers seems incredibly rude, and counter-productive to building or maintaining a culture of technical excellence.

ktizo7• 14 years ago

I had no idea that sock drawers were such a touchy subject.

However I would say that if you want to maintain a culture of technical excellence, it should be built well enough in the first place to cope with things like occaisional wayward comedy about the possible sock organisiation habits of fans of practical topology, without getting too upset about it.

Otherwise it isn't a very good culture of technical excellence and it will all fall apart the first time somebody sneezes.

libria2• 14 years ago

I've read and reread ktizo and I'm not seeing the negativity. He drew a correlation based on their attention to detail and if mistaken should be about as insulting as mathematical error.

Perhaps there's a cross-cultural interpretation associated with sock drawers that I'm missing. Granted there has been negativity on HN lately, but are we not manufacturing drama here?

//edit: I read it that he's impressed with their focus and passion, which sounds more like a compliment.

snowwrestler2• 14 years ago

Your commment strikes me as more negative than its parent.

kabdib• 14 years ago

I love reading about flight hardware. I have a bookshelf full of this stuff.

Mars itself is neat. But they haven't done much exploration with this rover yet, and so: Knots is what we got. :-)

kghose3• 14 years ago

Two words: zip tie.

sosuke• 14 years ago

Perhaps zip ties can't withstand the changes in pressures or heat. Expansion, contraction, and all that mess. I'm simply arm chair guessing here.

skorgu• 14 years ago

The link itself addresses this:

Overtightening of cable management bindings can cause conductor breakage, insulation damage, excessive chafing, and deformations between the conductive, dielectric, and shield parts of a cable, and no doubt a host of other issues. It is one of the classic problems with ratcheting plastic cable ties (i.e. "zipties") that they only have quantized adjustment steps and cannot be easily loosened. While zipties with a metal tooth insert do allow for smoother tightening, the possibility of this tiny metal part coming loose near electronics generally excludes their use. That zipties cannot easily be loosened or adjusted during tightening makes them more prone to being left in an overtightened state. Difficulty of adjustment might also be considered a possible strike against using the Constrictor Knot (and similar knots) for this application.

kghose3• 14 years ago

Well, neither wikipedia nor the linked article say why zip ties aren't used. I don't know what material the lacing is made from, but unless it is a natural thread I'm sure zip ties can be made from that material.

It might be that tension (which is what I worry about when I zip tie delicate things like optic fibre) is better controlled in hand tied knots, but zip ties can be tied pretty precisely.

uxp• 14 years ago

Some of the more higher resolution pictures suggest that the lacing is actually made from metal wire or synthetic fiber in a braid, which might have better environmental suitability than an injection molded solid plastic zip tie. Knots also provide endless tightening configurations, where as zip ties have quantified steps, which could simply be over tightened on an essential cable by accident providing a stress point for a small cable or wire to break at in a couple of years.

Also arm chair guessing.

randlet• 14 years ago

zip ties are addressed itfa.

tlb• 14 years ago

Zip ties are certainly quicker, but when everything is vibrating they concentrate the cable flexing stress at the edges of the zip tie. I've seen wires crack in my own robots from cable ties.

ChuckMcM2• 14 years ago

When there is an 'obvious' answer, its always useful to ask the question "Hmm, zip ties would have been easier/quicker than knots, do they know something I don't?"

It is the 'curious' response.

If you have used zip ties in adverse conditions you would immediately know they suffer from two huge issues, the first is that under stress the ratchet nib can break and they release, the second is that on a strength to volume and strength to weight ratio they are grossly inferior to any number of threads.

So for something you are sending very far away, and for which you have to put 4.3 ounces of launch system together for every ounce you want to land on the surface, mass and volume add up, and you can't really go out and replace a broken one can you?

stewartbutler2• 14 years ago

Also, zip ties are plastic. Most plastics decay when exposed to ultraviolet. As this is NASA, there is probably some funny polymer that can get the job done, but why fix what isn't broken?

jasonwatkinspdx• 14 years ago

Three words: read the link.

noonespecial2• 14 years ago

I can't use zip ties on my boat. Two months in the sun and they're toast. They quite literally turn to dust.

antsam• 14 years ago

An entire forum about knot tying?! Sign me up!

svdad• 14 years ago

This is awesome. I'm going to lace all my cables now.

In these kinds of applications, what do they use to attach the cables to something? It looks like on the rover they have special tie points built onto the rover surface -- is that what is done in other applications too?

stewartbutler2• 14 years ago

Either they are laced parallel to a support strut, which can be thought of as a very hard wire, or lashed down to some support point. You can also see this in large data centers.

http://www.reddit.com/r/cableporn

eckyptang2• 14 years ago

Great link. There goes my afternoon :-)

The first item is amazing as well (ST-124-M3 inertial platform i.e. Gimbal unit for Saturn V)

About: http://en.wikipedia.org/wiki/ST-124-M3_inertial_platform

Pron: https://upload.wikimedia.org/wikipedia/commons/4/44/ST-124_u...

This sort of engineering is as much art as engineering and I truly respect the people who designed and built it.

johnchristopher• 14 years ago

Why are the cables exposed ? Wouldn't it better to fix them inside the rover and only have the relevant ends pop out when there is a need to connect to a device located on the outside of the shell in order to reduce interferences and external damages ?

natep2• 14 years ago

My guess is that they have cables on the outside _and_ inside, and putting yet another cover over the outside cables would mean more mass. As-is, they only have to worry about wind and sand, so extra metal shielding is probably not necessary.

lttlrck• 14 years ago

Right. If they didn't care about weight they'd have used zip ties and braiding.

marshray2• 14 years ago

If an advanced alien species someday finds this rover on Mars (or probably any other space probe launched by NASA) and examines it, what will this method of knotting tell them about the state of human mathematics?

For example, is it possible that there exists another, more optimal, type of knot that we should have chosen had only our knot theory had been more advanced?

ars2• 14 years ago

I doubt it. See: http://en.wikipedia.org/wiki/Trefoil_knot

nicklaforge• 14 years ago

"Knot theory" always concerns strings that are joined at either end to form a closed circuit. Regardless, I don't think abstract mathematics does much for you when the problem is so simple and 'practical'.

ivix• 14 years ago

Does anyone know why so much cabling on Curiosity is on top of the vehicle, exposed to the elements?

Surely it would be safer to contain those cables in the body? It would just take a rock to fall on the rover from a cliffside or similar to damage those cables.

papercrane• 14 years ago

Just a guess, but maybe its to make diagnostics easier. If something is wrong they can image the cables and look for breaks.

noonespecial2• 14 years ago

For just a moment, I found myself worried about how they would hold up when it rained...

startupfounder• 14 years ago

Wouldn't that be a nice problem to have. The only way to fix it would be to send some humans to the rover for a repair job...

Retric• 14 years ago

There is not much in the way of 'elements' on Mars. If you look closely the cables are encased in something, but static electricity and dust storms are the largest problems and fairly easy to deal with.

eckyptang2• 14 years ago

Just had to post this photo which I found after looking around as it's related:

http://upload.wikimedia.org/wikipedia/commons/4/46/System_Te...

Saturn V instrument unit.

Awesome piece of engineering.

snowwrestler2• 14 years ago

Cool picture. It looks to me like most of those long-running cable bundles are secured with black plastic zip ties--ironic given the text of the article.

towndrunk• 14 years ago

If anyone is interested in more of these standard practices in regards to aircraft construction the following book details the proper methods that should be used.

http://www.amazon.com/Standard-Aircraft-Handbook-Mechanics-T...

delinquentme• 14 years ago

Can I get an explanation as to how the OP is making the claim that these are IN FACT these kind of knots? I mean I cannot see how this image is of sufficient resolution to support this.

Cable lacing on the Curiosity rover

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