Archive: 19 posts

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Okay so I tried searching a bit but couldn't find anything about this problem. So sorry if this has been posted before. But my problem is with pistons. Basically I'm trying to make a 2 axis "elevator" (ie. it can move horizontal and vertical) it looks something like this: ("o"s are blank space...) _____________________________________ -------piston--------glassblock----piston--------- _______dark matter support_____________ oooooooooooooooooo|||oooooooooooooooo oooooooooooooooooo|||oooooooooooooooo ooooooooooooooVert pistons.oooooooooooo oooooooooooooooooo|||oooooooooooooooo oooooooooooooooooo|||oooooooooooooooo ooooooooooooo___________ooooooooooooo ooooooooooooo|oooooooooo|oooooooooooo ooooooooooooo|oooooooooo| <--elevator ooooooooooooo|__v___h___|oooooooooooo ooooooooooooooooooooooooooooooooooooo vert and hor switches (in elevator) The problem is that when moved horizontally the elevator starts to rotate sideways and pull up wards. Then it speeds up until hitting the ceiling and exploding... I tried switching to strong winches and weak stiff pistons but it doesn't help. Any idea's on how to fix this? And help would be great. on a side note I had the same problem with a "boss" on a horizontal piston attached to dark matter. When moving away from the dark matter the "boss" would also illogically move "up" until smashing on the ceiling. I dunno if this is the same problem...

2010-05-05 00:51:00 Author: Yensoo Posts: 8

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ive had this a few times, sometimes just the arrangement of the pistons and winches can make this thing happen, try some different arrangements and make sure you have no strong opposing forces. That's all the help i can give though im not sure as to what the reason and absolute solution is

2010-05-05 01:00:00 Author: Littlebigdude805 Posts: 1924

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Yeah I've tried having 2 pistons and 2 winches on each axis spread fairly wide apart and it still somehow finds a way to rotate :s

2010-05-05 01:03:00 Author: Yensoo Posts: 8

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Things like this are bound to happen when you have many connectors connecting objects with other connectors. If you haven't, you should try: Making all the connectors stiff with max strength. Adding glass sliders for guidance. Adding 0-strength connectors for added stiffness. Using stronger materials, like stone.

2010-05-05 01:03:00 Author: Incinerator22 Posts: 3251

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Things like this are bound to happen when you have many connectors connecting objects with other connectors. If you haven't, you should try: Making all the connectors stiff with max strength. Adding glass sliders for guidance. Adding 0-strength connectors for added stiffness. Using stronger materials, like stone. I found those same tips when looking for help earlier. I have the support made of dark matter. The horzontal connection made of glass for "slideyness" and strength. The elevator itself made of cardboard so it's light. I have the pistons set to 0 strength and winches for movement. I have them spread really wide to stop rotation too. Nothing of the like seems to help... :c

2010-05-05 01:59:00 Author: Yensoo Posts: 8

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the problem is that when moved horizontally the elevator starts to rotate sideways and pull up wards. When dealing with this sort of design (sometimes referred to as a "piston cornerstone" design)... A - B | C ...assuming 'A' is made of dark matter, 'C' is your elevator, and the lines represent piston connections, then you need to ensure that the mass of block 'B' is at least as much as the elevator's mass. The reason is that the amount of strength that a piston has is relative to the masses of the two objects it connects. As long as you follow that rule, you don't need any extra stabilization, so in your design, you only need two pistons, and the slidey glass arrangement won't buy you any extra stability.

2010-05-05 14:46:00 Author: Aya042 Posts: 2870

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When dealing with this sort of design (sometimes referred to as a "piston cornerstone" design)... A - B | C ...assuming 'A' is made of dark matter, 'C' is your elevator, and the lines represent piston connections, then you need to ensure that the mass of block 'B' is at least as much as the elevator's mass. The reason is that the amount of strength that a piston has is relative to the masses of the two objects it connects. As long as you follow that rule, you don't need any extra stabilization, so in your design, you only need two pistons, and the slidey glass arrangement won't buy you any extra stability. Thanks for the tip! I'll have to try this later. I'll post again once I try it to let everyone know if it worked. Thanks again!

2010-05-05 14:51:00 Author: Yensoo Posts: 8

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Also, instead of glass blocks, you can try wheels. The same principles Aya mentioned would apply.

2010-05-05 15:19:00 Author: comphermc Posts: 5338

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The elevator itself made of cardboard so it's light. In addition to what Aya posted, note that pistons in LBP *only* exert the minimum force necessary to move their load, or in other words, are only as 'strong' as the load that you place on them. I know that it feels backwards, but giving your system a "light" cardboard load will add *instability*, NOT increase stability. Try this experiment: set up a light (cardboard, sponge,polystyrene) platform resting on an extended vertical piston. If Sackboy jumps on this platform, he can "smoosh" it down (cause the piston to contract by jumping on it). Now change the platform to something heavy (metal or stone) and note that Sackboy can no longer smoosh the piston down by jumping. As Aya said, it's a matter of keeping the masses of your blocks *heavy* (relative to Sackboy) and *balanced* between each other. The LBP physics engine also hates (doesn't work well with) pistons and winches connected in series or parallel (beyond 2, anyway). Follow the KISS rule, and suspend how you would build something in real life (hard to do, I know). -- Nanluin

2010-05-05 17:01:00 Author: Nanluin Posts: 98

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Follow the KISS rule... ...which I believe is to Rock n' Roll All Night, and Party Every Day!

2010-05-05 17:45:00 Author: Aya042 Posts: 2870

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This may sound dumb to you guys.... But what IS the KISS rule? haha

2010-05-05 17:55:00 Author: Yensoo Posts: 8

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When I created my elevator (which is now somewhere) I added some zero strength stiff springs, they help a lot.

2010-05-05 19:03:00 Author: napero7 Posts: 1653

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This may sound dumb to you guys.... But what IS the KISS rule? haha Engineering fundamentals: Keep It Simple, Stupid (though it varies depending on who you ask to the OP: I'd stick with aya's explanation with the increased mass of the middle piece. This will generally work. Try this experiment: set up a light (cardboard, sponge,polystyrene) platform resting on an extended vertical piston. If Sackboy jumps on this platform, he can "smoosh" it down (cause the piston to contract by jumping on it). Now change the platform to something heavy (metal or stone) and note that Sackboy can no longer smoosh the piston down by jumping. This isn't entirely accurate is it? It depends on what is connected to both ends of the piston. Put dark matter at the bottom of the piston and you can quite happily have a stable platform with far more strength than is needed to keep the object at the top pusted outwards. The overal strength depends on the mass of the materials at both ends, so your experiment would fail if the object at the bottom was sufficiently heavy (as per aya's above post). In addition, the force that the piston applies is also based upon the speed of the piston (range / time), so a piston with 0.1s time will be less susceptable to the effect you describe. ^ That is from memory, so feel free to verify, but I just wanted to expand on the simplified info as it's possibly misleading, unless I have remembered wrong and my entire understanding of littlebigmechanics has gone to **** in my month sabatical

2010-05-05 20:11:00 Author: rtm223 Posts: 6497

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okay so problem solved c: Thanks to all of you for great suggestions and help. It turned out to be, like most of you said, the middle joint. To solve the problem I replaced my not so big glass block with a large stone "car" with loose wheels and 2 strong stiff pistons starting at dark matter on the left and going our to the car to the right. It seems to be pretty stable and hold together fairly well. Now I just have to see how well it'll hold up to loads it's subjected to. (oh btw I kept the elevator itself cardboard and it seemed to work) Now I just have the problem with the boss. It still doesn't make sense to me cause it's only ONE piston with no joints, only moving left and right and it's attached to dark matter... not sure whats going on there... haha

2010-05-05 20:18:00 Author: Yensoo Posts: 8

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This isn't entirely accurate is it? It depends on what is connected to both ends of the piston. You have far, FAR more LBP Create experience than I do RTM, so I'll defer. I was basing the above on my development of the Growing-Shrinking Toadstools in my current level -- essentially horizontal platforms mounted on vertical pistons. The base is the same material as the platform, but is glued to a large framework of stone which is pinned by Dark Matter. So perhaps my observation is flawed by the fact that I couldn't use the stone framework itself as the base (the base had to remain as a separate entity for toadstool 'watering' purposes. -- Nanluin

2010-05-05 21:07:00 Author: Nanluin Posts: 98

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Use a rack! Have a glass rack, either horizontal or vertical, and connect two pistons to it in parallel, attached to DM. Set one to stiff and 0 strength with extra length than needed, and set the other to stiff and the exact length you need. Now, connect up a small glass block in the glass slider and attach this to another piston, set to stiff. This glass block then glues on the back of your elevator. And as long as this setup is in the thick plane, you can hide it with a thin plane material between glass and elevator. Simples!

2010-05-05 21:14:00 Author: Holguin86 Posts: 875

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I find it helps to have a stiff spring set to zero strength helps to keep things straight, without affecting the length of whatever you're using

2010-05-05 21:25:00 Author: Weretigr Posts: 2105

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To solve the problem I replaced my not so big glass block with a large stone "car" with loose wheels and 2 strong stiff pistons starting at dark matter on the left and going our to the car to the right. It seems to be pretty stable and hold together fairly well. Now I just have to see how well it'll hold up to loads it's subjected to. Frankly, even that sounds like overkill. You should be okay without the wheels and the multiple pistons, as long as the mass ratios are okay, but I guess "if it ain't broke, don't fix it" ultimately applies. Now I just have the problem with the boss. It still doesn't make sense to me cause it's only ONE piston with no joints, only moving left and right and it's attached to dark matter... not sure whats going on there... haha Might be a similar issue if the 'boss' itself uses connectors to connect, say, its arms and legs to a body, or whatever. If so, then make sure that the piston from the DM is connected to the heaviest component of the 'boss'.

2010-05-05 22:05:00 Author: Aya042 Posts: 2870

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hey i can fix it if you want just send a mssg to my psn (same as name) and i help you out ok

2010-05-06 01:56:00 Author: maximboyextra95 Posts: 4

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