[OPEN-SOURCE] Machinery Modelling Toolkit

[OldRaven]

@;553461

A bit of illustration for torsion bars spring:

On the left, torsion spring is in the relaxed state and is effected only by gravity which we ignore for simplicity. On the right, torsion spring holds a portion of mass of the tank. So how do we get to this:
We can set angular limit to 90 degrees, so handle can turn up to M1 and M2. M1 and M2 would be the points where maximum force of the spring is generated. So spring force will go from -Angular Position Strength at M1, to 0 at A and to +Angular Position Strength in M2.
We want force of the spring to be equal "Mass of tank in kg * acceleration due gravity / amount of wheels " at 15 degrees (point B), which is 70% from point A. Which means that we should set Angular Position Strength to:
(Mass of tank in kg * acceleration due gravity / amount of wheels) * 1.3
to add 30% of force that we should have at M1 and M2.

We can take different angle. For example default position is 30 degrees and we allow freedom of 60, it means that lever can travel from 0 to 60 degrees and if our desired position under tank load is 15 degrees then we need to set Angular Position Strength as:
(Mass of tank in kg * acceleration due gravity / amount of wheels) * 2
as 15 degrees is a half way between relaxed position and fully compressed.

makes sense… the initial 15 degrees when it standing on all wheels was more or less a measurement. If I rotate the springarm 15 degrees from its horizontal position… the wheels seem to be at the point where they are in real life.
I will experiment with the angle and weight. I did not enable any weight of the actual wheel or springarm (yet)
My fear with settting M1 at 90 degrees is that when you drop the tank on schene activation the wheels go the other way… Haven’t tried that.

Contraints always seem to be some sort of struggle… for years I’ve setup 3D character for film and animarion in general and constraints always seem kind of iffy. It’s probably because of how they are implemented. They always seem to do “something” … relusting in all sorts of wobble and errors.
I’m curious how they do it in Vortex, I’m pretty sure they wrote their own physics code for it. In the long run I think it would be nice to have some sort of seperate torsion bar node, just like the spring… if you do it with the current constraint it’s kind of a pain to setup… and I’m curious if it will ever react the way you predict this way.

If you want me to send you the tiger to also experiment with the torsion bar, just let me know… I can send it to you. If it’s all working we can also include the tiger as an example for other people to try.