Problems with lifting objects

[KjetilMV]

Hi

I have a setup with wire-like ObiRopes that are supposed to connect to an object and lift it.

The end particle is pinned to a Obi/Rigidbody object ("EndPoint").
When connected to object (by script), a hingeJoint is created on the EndPoint and the object to be lifted is set as the connected body on the hingejoint.


This works, but the wire get's really stretched before being able to lift the object off the ground - and then almost like a rubber band. As I pull in the restLength, strain value rises (towards 5), when object finally bounces off. Before connecting the wire is very rigid with distance and tether constraints at max stiffness and very high iteration settings in the solver.



Hope someone can point me in the right direction!

Thanks

[josemendez]

Hi

I have a setup with wire-like ObiRopes that are supposed to connect to an object and lift it.

The end particle is pinned to a Obi/Rigidbody object ("EndPoint").
When connected to object (by script), a hingeJoint is created on the EndPoint and the object to be lifted is set as the connected body on the hingejoint.


This works, but the wire get's really stretched before being able to lift the object off the ground - and then almost like a rubber band. As I pull in the restLength, strain value rises (towards 5), when object finally bounces off. Before connecting the wire is very rigid with distance and tether constraints at max stiffness and very high iteration settings in the solver.



Hope someone can point me in the right direction!

Thanks

It all comes down to the mass ratio between the rope and the object hanging from it. The higher the mass ratio, the slower the rope will converge (and the stretchier it will be). This is common behavior in all physics engines. It is generally not reccomended to exceed a mass ratio of 1/10 (load ten times heavier than the rope).

Either make the rope heavier, or the load lighter. Also, try to reduce the fixed timestep, as taking smaller physics steps will make the rope less stretchy.(https://docs.unity3d.com/Manual/class-TimeManager.html).

[KjetilMV]

It all comes down to the mass ratio between the rope and the object hanging from it. The higher the mass ratio, the slower the rope will converge (and the stretchier it will be). This is common behavior in all physics engines. It is generally not reccomended to exceed a mass ratio of 1/10 (load ten times heavier than the rope).

Either make the rope heavier, or the load lighter. Also, try to reduce the fixed timestep, as taking smaller physics steps will make the rope less stretchy.(https://docs.unity3d.com/Manual/class-TimeManager.html).

Thank you.

In my setup, the rope particles have a mass of 1, but the last particle (where the hook is) is 10 or 100. This last particle is pinned to the "End Point" which has the same mass. Lastly, the lifted object has mass in the thousand. Did try reducing the mass of the lifted object before to no improvement, but I'll try it again later today when I'm back at work.