1.9.8 - Weak +inf Nm Hinges

[Ivan]

Legacy mode 1 hinges with +inf Nm torque and are pretty weak in comparison to legacy mode 0 hinges.
I think hinges/axles, if braking, should act like fixates if the torque is set to +inf.
See the attached scene:

Weak +inf Nm Hinges.phz

(22.63 KiB) Downloaded 28 times

EDIT:
I also think that springs with the constant of +inf N/m shouldn't be stretchable/compressible (like solid bodies).

[Someone Else]

Non-stretchy hinges are going to be near impossible, I think. No matter what the circumstances.

The way to fix it (or at least get closer) would be to increase sim.frequency.

All a hinge does, assuming it's truly inf-torque and zero-speed (or braked, no difference) is apply a force based on the distance between its two attachment points.

I've also noticed that from 1.9.7 to 1.9.8, hinges have gotten a lot stretchier. In 1.9.7, I was able to place an infinite-torque, 3,000 rpm hinge near the end of an, oh, 1x8 aspect ratio box, and the hinge stretched about the length of the box. Note that this hinge will alternate the direction of the box each frame, if sim.frequency = 100.

This same contraption in 1.9.8 sends the box spazzing out far, far from where it needs to be.

I have noticed that infinite-torque autobraked hinges are in fact pretty weak in the rotational sense too, even in 1.9.7.
For some minor project, I was able to get around this by using the Bend feature. In a hinge script menu, set bend to true, bendConstant to +inf and bendTarget to some number. You will select this number based on where you want the hinge to point, it should be a float somewhere between 3.14159265358979323846264 and -3.14159265358979323846264. It's in radians, so you could also place it between (-1) * math.pi and 1 * math.pi.

[emilk]

You can experiment with the "bendConstant" of the hinge. Set it to +ínf (along with motor strength) to get a motor that is as strong as needed. May cause instabilities with more than one such motor (in general, infinitely strong things are dangerous).

For strechiness, you can set the hingeConstant to +inf. (hingeConstant==NaN gives the default hinge strength of Sim.solveConstant=1e8 N/m).

As often is the case with solvers, infinite stiffness causes instabilities.

[Ivan]

Thank you very much for your replies!
I didn't know what bend is.