The Space Arm - Flexible connection system using the grabber!

[zeel]

So one thing I have been wishing for has been movable parts, so that sections of a ship can rotate or bend. Though there are no such parts, I have found a way to build them, to an extent. The key is the pivot ability of the grabber, all you need to do is link lots of small grabber segments together and you can make a rather fun flexible chain. Add reaction wheels and it's a fairly useful arm. . .

The design is simple, each segment is a fuel tank, a reaction wheel, and a grabber.

Those Are connected to a support shaft using mini docking ports and girders. The support shaft is made of structural fuselage and ASAS units, the ASAS are only there for proper spacing.

Then I simply stack many of those units together. And action group is used to arm the grabbers, and another to undock all but the first docking port (the first one needs to remain as long as I want to keep my arm attached to my ship).

This creates a highly flexible arm structure, simply using the maneuvering keys causes t to swing around. You can unlock or lock and joint to get a rigid shaft, an elbow, or a tentacle.

An interesting quirk is that your action group for arming the claws will not release them even if you close their housing. This means they stay stuck even while hiding the claw parts, which I think looks a bit nicer.

Such a system would be ideal for linking multiple large vessels (or asteroids) as the flexible arm will not stress that would destroy a rigid joint, allowing multiple very massive objects to be connected without tearing each other apart (in theory at least). A similar (but much shorter) system with multiple arms could allow very large clusters of engines to anchor to E class asteroids with strong foundations without losing the ability to align them with the center of mass, with multiple pivot points even tripods could be adjusted to align the engines.

Or some kind of tool could be attached to the end instead of the last claw. Spotlight? Kerbel in a char? Docking port? Missile launcher? Engine??? Just about anything, and then it can be pointed wherever you need it.

Finer control could probably be had with some RCS jets, and I'm sure a slightly better system for setting the thing up is probably possible. I'm not sure how well it will connect in space, but I do know it will work on the surface - you just have to undock the nodes one at a time, and hope that they all link properly. Some more research may reveal better ways of aligning them.

I recorder a a video to demonstrate:

Edited April 7, 2014 by zeel

[zeel]

I managed to put one (actually a pair) into space. The result was. . . interesting. If you enable SAS they flail around like mad. My ship was very low mass so it did not fair well. There is far too much torque in the arms for a small craft to handle (it just spins as they flail) but mounted on an asteroid or very massive ship they would do well. Interestingly, to deploy them in space you need to accelerate into them, not too fast or they will fail to connect, but if you do not accelerate the segments will simply drift away.

I just wish it was possible to dock two ships without sharing control. Then as long as the arm is linked by a docking port you could control it without spinning the ship. As it is you can't control the arm unless it is attached to something massive enough that reaction wheels won't turn it.

[Random Tank]

Couldn't you use RCS, which is only mounted on the Arm itself? So the main body of the craft had no turning torque? (You could still have reaction wheel on it, just make sure you turn them off)

Awesome work by the way, looks really cool!

[zeel]

Probably, perhaps even only putting the reaction wheel on the end would held as well. It certainly requires more testing of different designs.

Removing the torque altogether and simply using it to chain things together would be cool though. You could dock it before releasing the pivot, and then loosen it up to avoid breaking things.

[Random Tank]

Yeah, it's an awesome idea, props to ya! It'd be cool to make aesthetic pipelines between roids in space, making awesome stations! A little expanse on my suggestion: Put 4 RCS Thrusters on the end of the arm, and put 2+ Reacton Wheels on the main rigid body; you could then turn SAS on, and it should keep the main body stable and hopefully not disrupt the arm; you can then control the arm with the RCS Strafe controls, while the body (should) stay stable. This basically means you could control them independently of each other (if it works)!

You could even use your idea for docking arms for huge ships with crap/no RCS controls!

[greg12]

I had this exact idea. I built some prototype after the ARM patch release. I just didn`t find any use to it yet.

If you use only one or two, it could be use as a sky-crane cargo stabilizer. I also tried to use as a helicopter rotor axle but I had issues with rotating it in 360°.

[Xaelath]

This looks epic!

[zeel]

Yeah, it's an awesome idea, props to ya! It'd be cool to make aesthetic pipelines between roids in space, making awesome stations! A little expanse on my suggestion: Put 4 RCS Thrusters on the end of the arm, and put 2+ Reacton Wheels on the main rigid body; you could then turn SAS on, and it should keep the main body stable and hopefully not disrupt the arm; you can then control the arm with the RCS Strafe controls, while the body (should) stay stable. This basically means you could control them independently of each other (if it works)!

You could even use your idea for docking arms for huge ships with crap/no RCS controls!

I had not considered using the strafe keys instead! That might be far more stable. And I can easily disable the main crafts RCS jets when I need to move the arm. I just wish that you could add the pivot control to action groups. If you could switch from rigid to snaky on the fly that would be amazing.

[Random Tank]

I had not considered using the strafe keys instead! That might be far more stable. And I can easily disable the main crafts RCS jets when I need to move the arm.

You're welcome! Anyway, thank you for coming up with the awesome idea in the first place! Another tip: Use 4 inline RCS thruster; this half's the thrust of the thrusters compared to the multi directional ones (because you won't need a lot of thrust) which will save you RCS fuel; it also prevents the useless up & down thrust from happening.

I just wish that you could add the pivot control to action groups. If you could switch from rigid to snaky on the fly that would be amazing.

Awww can you not? That's a shame, I hope they add that asap!

[KN_Namida]

I'm thinking... If you added fuel lines between each segment, maybe with the help of some little cubic girders if you lack the space to connect them...

And putting a docking port instead of a claw on the end of the last segment...

Could you use it in space stations as a refueling arm? it would be super easy to move it andconnect it to a nearby ship, instead of moving the whole ship into the station

What do you think?

[Random Tank]

I'm thinking... If you added fuel lines between each segment, maybe with the help of some little cubic girders if you lack the space to connect them...

And putting a docking port instead of a claw on the end of the last segment...

Could you use it in space stations as a refueling arm? it would be super easy to move it andconnect it to a nearby ship, instead of moving the whole ship into the station

You wouldn't need the fuel lines as as soon as you dock it becomes one ship; allowing you to transfer fuel by clicking + alt-clicking tanks; plus it would be better to have the Klaw on the end if the arm so you can dock anywhere on another ship rather than at a specific docking port.

Nice suggestions anyway; it'd look cooler at least!

[zeel]

You're welcome! Anyway, thank you for coming up with the awesome idea in the first place! Another tip: Use 4 inline RCS thruster; this half's the thrust of the thrusters compared to the multi directional ones (because you won't need a lot of thrust) which will save you RCS fuel; it also prevents the useless up & down thrust from happening.

Awww can you not? That's a shame, I hope they add that asap!

That is what I did, and it's not as great as you would think. You see the game tries to correct the jets based on center of mass to move the ship as directed. So as the arm swings the same key will trigger different jets based on the angle of the arm. The result is that the RCS is no better at controlling it than the reaction wheels. The good news is that only putting the reaction wheel on the end works well. Still difficult to control because the game isn't treating it as an arm, but an extension of the ship - it doesn't get that activating the trust in a given way will just swing the arm instead of the whole ship. That's good if you have a rigid arm the maneuvering system will still work. Bad if you want a flexible arm you can control.

I'm thinking... If you added fuel lines between each segment, maybe with the help of some little cubic girders if you lack the space to connect them...

And putting a docking port instead of a claw on the end of the last segment...

Could you use it in space stations as a refueling arm? it would be super easy to move it andconnect it to a nearby ship, instead of moving the whole ship into the station

What do you think?

Quite doable. Though the fuel lines really won't help, the cross feed will work without them. One thing I am considering is carry bunch of attachments, just grab em (no need to use an actual docking port!) and they could be anything from a docking port to an engine.

[zeel]

So after some testing I have concluded that the best control comes from a single reaction wheel on the end, as well as some RCS ports. Plus the ship/asteroid needs very high mass (like a whole SLS big tank at least). As long as you can disable all reaction wheels/RCS on the ship the arm is relatively controllable. It's a bit fiddly since the same keys don't always move it the same way, but if you are careful it can be done.

Furthermore I found a useful exploit: Returning to the space center locks all pivots. So if it gets really crazy or you want it locked in a very specific configuration you can just hit escape and then return through the tracking station. This is super helpful if you go into a spin since actually accessing the context menu on the things in nearly impossible if they move too fast. The down side is that this means all your flexible lines will go rigid if you unload your vessel. The things are still super bendy though, so I doubt that will break anything as long as you remember to free the pivots before making any adjustments.

Oh, and one last bit of advice: Watch out for your solar panels.

[ScottyDoesKnow]

Furthermore I found a useful exploit: Returning to the space center locks all pivots.

Actually I think this happens any time you timewarp.

[Random Tank]

Bugger, I was hoping that would work... Ahh well; at least you can control with reaction wheels; I'll just use a few C class or bigger roids to hold the thing in place! Maybe using fine controls may help (default key is Caps Lock if you didn't know) to make it easier to control...

Activating time warp (as in not Physics Warp) should freeze the Arm too; as it stops all physics which includes rotation (real useful for stopping out-of-control ships!). I think if you have only the reaction wheel on the arm activated, and the arm unlocked, then carefully control each section with fine controls, it should be too hard to control...

Oh, and one last bit of advice: Watch out for your solar panels

He he he, I'll keep that in mind

[Jeb Cubed]

So many ideas so little time, that is the most clever thing I have seen in this game so far.

[KN_Namida]

Also, guys, all this bendyness gave me an idea, but the first attempts at it proved to be not really succesful. Feel free to try your designs and ideas, see if we can improve this

I'm talking about a ROADTRAIN with free-pivot grabbers between each section

My first design had some pendulum-effect issues, probably because the sections were not perfectly aligned, so moving forwards (when I locked the steering of all the back wheels) caused some of the sections to curve, and after a whil the whole thing started moving like a snake, hehe... Needs some redesign, but it's promising!

This grabbing device really added a whole new level of gameplay here... Now I'm imagining a battle between 2 mechanical space krakens, with space arms for tentacles, in a future multiplayer KSP server... I love this game :>

[zeel]

Also, guys, all this bendyness gave me an idea, but the first attempts at it proved to be not really succesful. Feel free to try your designs and ideas, see if we can improve this

I'm talking about a ROADTRAIN with free-pivot grabbers between each section

My first design had some pendulum-effect issues, probably because the sections were not perfectly aligned, so moving forwards (when I locked the steering of all the back wheels) caused some of the sections to curve, and after a whil the whole thing started moving like a snake, hehe... Needs some redesign, but it's promising!

This grabbing device really added a whole new level of gameplay here... Now I'm imagining a battle between 2 mechanical space krakens, with space arms for tentacles, in a future multiplayer KSP server... I love this game :>

Oh I hadn't though of trains. That could be very cool, and easier to set up too (since they would start on a flat surface). I am going to give it a try.

[zeel]

Well the train is. . . interesting. I managed to make the planet disappear more than once - not sure why that happens. But they work really well as long as all the back cars have the wheel steering disabled. Though building them is something of a pain, it's really cool how they turn out. Obviously it would be more useful on another body, moving a very large complex. A car for fuel, a car for RCS, a research lab, etc.

Also: Why did this thread move to spacecraft exchange? This is not a craft, nor is anything being exchanged. It's a concept for using grabbers in interesting ways. . .

Edited April 8, 2014 by zeel

[Blue]

The R means Exquisite.

I imagine it won't be long before Squad realizes the inevitability that they'll need to implement real arm manipulator parts...

[KN_Namida]

Well the train is. . . interesting. I managed to make the planet disappear more than once - not sure why that happens. But they work really well as long as all the back cars have the wheel steering disabled. Though building them is something of a pain, it's really cool how they turn out. Obviously it would be more useful on another body, moving a very large complex. A car for fuel, a car for RCS, a research lab, etc.

Also: Why did this thread move to spacecraft exchange? This is not a craft, nor is anything being exchanged. It's a concept for using grabbers in interesting ways. . .

I did some more experiments with the roadtrain. You're right, Kerbin may "disappear" while connecting the segments, even though it only happened to me once. I just reverted the flight and then everything worked fine.

Also, the weird pendulum/whip curving problem was due to the fact that, even if I locked the steering of all the wheels except the front-end ones, I didn't disabled their motors, so all the wheels were thrusting forwards, instead of being pulled by the main segment. I deactivated all the wheel motors (except for the ones of the front pair of wheels, of course) and everything worked fine

Of course, the roadtrain had a much lower acceleration this way, but it was a lot more drivable. And even more realistic, you might say. I successfully assembled and drove a 9-segment roadtrain around the KSC, and each segment consisted of a lab module + more crap (so they weighted tons, hehe).

[zeel]

What we need is a part that's just the pivot. Connecting on both ends, but without the claw. Plus it would be nice if docking ports/claws could be set to "isolate" mode - the two ships would no longer share control. Then it would be a thousand times easier to move as the end would be treated as a probe that just happened to be attached to a flexible arm. You could just switch too it like a separate craft. Edited April 8, 2014 by zeel

[Technical Ben]

I managed to put one (actually a pair) into space. The result was. . . interesting. If you enable SAS they flail around like mad. My ship was very low mass so it did not fair well. There is far too much torque in the arms for a small craft to handle (it just spins as they flail) but mounted on an asteroid or very massive ship they would do well. Interestingly, to deploy them in space you need to accelerate into them, not too fast or they will fail to connect, but if you do not accelerate the segments will simply drift away.

I just wish it was possible to dock two ships without sharing control. Then as long as the arm is linked by a docking port you could control it without spinning the ship. As it is you can't control the arm unless it is attached to something massive enough that reaction wheels won't turn it.

Thank you to you and the OP. I've just figured out. We can build "station building" arms for moon bases or orbital bases now.

[zeel]

This grabbing device really added a whole new level of gameplay here... Now I'm imagining a battle between 2 mechanical space krakens, with space arms for tentacles, in a future multiplayer KSP server... I love this game :>

Space Kraken you say?

Posted more in its own thread.

Edited April 9, 2014 by zeel

[Redshift OTF]

Awesome discoveries! I could make my own space worm!

If you attached an engine to it could you have some kind over directable thrust or would it be pointless?