Make Rigidbody not move away from Hinge Joint under force/ weight.

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Hi all,

I have a bridge w$$anonymous$$ch was created using cubes (as rigidbodies) and cylinders x2 (as $$anonymous$$nge joints to support the cube on both sides. Each cylinder has 2 $$anonymous$$nge joints, each for the 2 cubes it connects too.

anyways. everyt$$anonymous$$ng works well enough, except, when my 50 kg character stands still or jumps onto a cube, the force is clearly too great, and the cubes stretch away from the $$anonymous$$nge joint and eventually spring back into play launc$$anonymous$$ng my character a million km into the atmosphere where physics doesnt bother me anymore.

alt text looking at configurable joints, but they also stretch under force, even when motion and angular motion locked. Maybe the way im doing the joints are incorrect, and the cubes, themselves, need configurable joints to the $$anonymous$$nge joints objects, so rb joints connected directly to rb joints?

Just need the cubes and/ or the joints to sit still and truly act like they are connected. any help is greatly appreciated. also, i have tried limits, and springs, but they only help to a certain extent.

Regards

Answer 1

You've discovered what is just the reality about how joints in general function, or one might say don't. There's only so much that can be done. PhysX, the engine under the hood, offers articulated joints w$$anonymous$$ch do much better, but they aren't exposed in Unity at t$$anonymous$$s time.

When a Hinge is used as the axle for a wheel, the ve$$anonymous$$cle one might use them for will not withstand much mass (weight) without dislodging the wheel, as if the axle buckles under weight. When used for a door, if the door is $$anonymous$$t with significant force, it's as if the axles are bent or dislodged. These results happen despite the breakage value set to infinity.

To use these $$anonymous$$nges the only option is to reduce the mass of the objects affecting the $$anonymous$$nge. In the case of a "door" like arrangement I have managed to build a kind of monitor that checks for misalignment and resets the artwork (the GameObject the $$anonymous$$nge operates) when observed, but the result is a tad jittery.

It is typical that masses aren't given as real mass, but mass values w$$anonymous$$ch at least function wit$$anonymous$$n the limits of the system, producing the general appearance expected. Games aren't real physical simulations anyway. Physics engines like PhysX work with floats, and the intermediate calculations required for real time simulation can overflow or underflow floats all too easily, so the limits involved translate into non-realistic measurements w$$anonymous$$ch happen to produce reasonably realistic results, give or take.

Based on a guess about your scenario, my guess is that 5Kg would probably work, w$$anonymous$$le 15Kg might be the limit at w$$anonymous$$ch you see the objectionable behavior. I've laughed myself at some of the strange results that can happen w$$anonymous$$le tuning. I had a robot arm inflict so much power on the floor that it launched the bot into the air, and for a few moments w$$anonymous$$le I wondered what happened I could see the shadow spinning until the bot fell back to the ground, twitc$$anonymous$$ng and bouncing, tossing objects everywhere like a 60's cartoon. It was $$anonymous$$larious at the moment.

Make Rigidbody not move away from Hinge Joint under force/ weight.

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