by ArtF » Fri Mar 17, 2023 1:13 am
Bill:
It could be they are slightly different files, I probably quickly uploaded a slightly newer version as GearotionMotion1. I usually only announce when
something changes. I am still working on force issues so I haven't announced that 2.01 is actually online. It adds a button that creates a
Anchor escapement with a couple of clicks. I am trying to get it all to fire properly before I did a video or announced it is all.
I have discovered a couple things.. (experiment with the Anchor if you like..), HULL creation is now 4 times faster.
1) A structure like the Pallet arm on the Anchor benefits from having more hulls, I override such a structure to tell it a maximum of 512 hulls
during hull creaton. It usually makes about 250 - 280. More hulls doesn't slow one down much unless you are in constant collision. This added
hull number makes the sliding pallet lift faces slide easier and are harder to get to hang up on edges.
2) You need to add a center of mass about half way down the pendulum arm, so that gravity properly affects it. This is part of a larger discussion
to be had about Center of Mass of objects. The anchor will tick properly and speed up or slow down as you change gravity. A 300mm
pendulum does give about 1 second period at 9800mm's/sec gravity, so the math adds up.
3) Do not orient lock any item unless it shares a shaft with something else. (preferable with a bit of mass. Orient lock the added gear
or item if you wish. This added mass allows the re-orientation forces to balance much easier so performs much better.
Overall, the physics is working quite well and more robust than many sims I've seen..but.. and there's always a but,
escapements are really hard for sims to do, the sliding and force transfers are small on clock escapements, so getting it
right is hard, and I'm not quite there as yet.
Honestly , its so close I can taste it.. but I can describe what the issue really is..
In Bullet, the center of mass (COM) of an object is at its origin. When you set a shaft hole in an object ( the main shaft I mean ),
the objects origin is placed there as all shafts originate at mesh origin. This creates a problem as gravity is applied at origin
as its assumed to be the COM. Placing a COM object onto the pendulum fixes the problem in most ways,but one..
The pendulums lock to its shaft is "slippy", as if a grub screw is loose. This is caused because the solvers see the force needed to
rotate the pendulum to match the shaft as incorrect as the COM isn't properly taken into account. This causes tooth slippage at times
during ticking. I'm pretty happy with most things, and how its all working, ( I do have a list of corrections needed on various fronts),
but overall its all very good and getting better..except escapements begin still too picky...
I added an Anchor button because ostensibly the Anchor is the easiest and most reliable escapement as long as the math is correct
on its creation, so for Kinetic artists its a great energy system. ( So the button will try to ensure all is good for a test clock..)
Im working on a solution to what you'll see is a slipping shaft error caused by the mass COM offset.
Art
Bill:
It could be they are slightly different files, I probably quickly uploaded a slightly newer version as GearotionMotion1. I usually only announce when
something changes. I am still working on force issues so I haven't announced that 2.01 is actually online. It adds a button that creates a
Anchor escapement with a couple of clicks. I am trying to get it all to fire properly before I did a video or announced it is all.
I have discovered a couple things.. (experiment with the Anchor if you like..), HULL creation is now 4 times faster.
1) A structure like the Pallet arm on the Anchor benefits from having more hulls, I override such a structure to tell it a maximum of 512 hulls
during hull creaton. It usually makes about 250 - 280. More hulls doesn't slow one down much unless you are in constant collision. This added
hull number makes the sliding pallet lift faces slide easier and are harder to get to hang up on edges.
2) You need to add a center of mass about half way down the pendulum arm, so that gravity properly affects it. This is part of a larger discussion
to be had about Center of Mass of objects. The anchor will tick properly and speed up or slow down as you change gravity. A 300mm
pendulum does give about 1 second period at 9800mm's/sec gravity, so the math adds up.
3) Do not orient lock any item unless it shares a shaft with something else. (preferable with a bit of mass. Orient lock the added gear
or item if you wish. This added mass allows the re-orientation forces to balance much easier so performs much better.
Overall, the physics is working quite well and more robust than many sims I've seen..but.. and there's always a but,
escapements are really hard for sims to do, the sliding and force transfers are small on clock escapements, so getting it
right is hard, and I'm not quite there as yet.
Honestly , its so close I can taste it.. but I can describe what the issue really is..
In Bullet, the center of mass (COM) of an object is at its origin. When you set a shaft hole in an object ( the main shaft I mean ),
the objects origin is placed there as all shafts originate at mesh origin. This creates a problem as gravity is applied at origin
as its assumed to be the COM. Placing a COM object onto the pendulum fixes the problem in most ways,but one..
The pendulums lock to its shaft is "slippy", as if a grub screw is loose. This is caused because the solvers see the force needed to
rotate the pendulum to match the shaft as incorrect as the COM isn't properly taken into account. This causes tooth slippage at times
during ticking. I'm pretty happy with most things, and how its all working, ( I do have a list of corrections needed on various fronts),
but overall its all very good and getting better..except escapements begin still too picky...
I added an Anchor button because ostensibly the Anchor is the easiest and most reliable escapement as long as the math is correct
on its creation, so for Kinetic artists its a great energy system. ( So the button will try to ensure all is good for a test clock..)
Im working on a solution to what you'll see is a slipping shaft error caused by the mass COM offset.
Art