Animation troubles with chain

[sakura13]

Hi guys,

I'm really desperate I'm trying for several days to animate a chain which pulls an object backwards and rolls in, I tried with Bones and ik spline but collides, I tried with Path deform works partially but then goes through the object when tilting I'm really desperate and don't know what to do. It is clear that it goes through because the chain swings completely instead of staying in place and only a certain area moves but I have no idea how to solve this.

Here is the animation

and here is the construction where the chain should go

Hope who can help me greetings

[leeminardi]

If I understand the action correctly, as the chain is pulled the large wheel rotates and moves at a speed faster than the chain due to the shortening of the chain as it is wound up on the spool.  Yes?

Do you want the chain to be taut through its entire length as the spool  winds up the chain? As it rolls in do you want the chain to wrap around itself?  If so, you might consider three phases of action.  Helical paths at the two spools and a straight segments connecting them. Or consider one spline that uses a spline IK control modifier to control the shape of the chain.   Does the chain need to be discrete links or can a texture and bump map be used on a swept surface?   I'm not sure I have a solution but it looks like an interesting challenge.

Can you post a model of the assembly with a segment of the chain?

[sakura13]

the chain is in the middle and pulls on the bar so that the two rockers on the left and right are pulled backwards and rotate, the chain slides over the small roller and rolls in over the large roller. After releasing the lever, the machine works with compressed air and the bucket automatically moves forward again due to its own weight. Yes the chain has to be full length and rolls in after pulling it, i tried with 2 points and ik spline but the problem is the chain goes through the car. To example but take care its really loud

https://www.youtube.com/watch?v=HkYceH4JU3o

[sakura13]

Hmm i tried ik spline but the problem is the chain should move on the spline too, like a belt for a production line so it moves only at the spline with a little bit deformation at the pulling I hope you know what i want to say do you have discord or something like that maybe its better to talk about it there

[leeminardi]

From the video it looks like the chain is under constant tension except perhaps at the end when the bucket is dumping its load.

Can you post a Max file with most of the extraneous object to the action removed?

[sakura13]

Sure I have 2 Versions the belt is one object and the other one with seperated ones with ik spline which version do you need and which 3ds max version?

[leeminardi]

Let's try the one object version in Max 2021 format.

If possible can you make an image with a rough (hand drawn is ok) showing the chain in what you would think would be its shape in the initial, final, and intermediate positions.

[sakura13]

I did a spline on it but you can changed the part where it is hanging down its sad that I dont find the better video anymore, it was outside and the person was controlling it. Left handle is to pull back or reset position and right handle is to drive normaly I think. Here is a testrender of belt. And really thx for your help, my problem is iam not an animator, its my first try with staff like that 🙂

[sakura13]

i hope all is fine with files and so on and thx again

[leeminardi]

I hid a few objects in your file and colored a couple of others.

1. Your file has the Display Units set to meters and the System Units set to centimeters. It is best to have both set to the same units.  What should that be?
2. Line003 does not look right.  Is this supposed to be the path for the chain?
   
3. It looks you converted the chain to an Editable Poly. Why?
4. From the video and basic kinematics, I think the chain passes over the top yellow roller.  You have it on the bottom.   I think it should look like this at the start.  Do you agree?
   
5. The following image shows the approximate position when the buck has rotated 90°.  The red line shows what shape I think the chain should take..
   The take-up wheel is a portion of the entire  blue object.  It should be independent.

[sakura13]

1. centimeters about the units I thought I cant change it anymore, because troubles after changing
2. yeah i saw it too after i uploaded sry the 2 vertex need to snap to line like at the updated version but i corrected only the line and yes it is line003

3. Because I model it with a cube

4. yes it was a misunderstanding from my side you are correct

5. yep you right i think it was a logical mistakes from myside sry.

Oh i found the better video but its on facebook here the link

[sakura13]

Oh i forget to say its for realtime unity engine I dont know it is important or not?

[leeminardi]

While working with the file I discovered that the transform matrix for the yellow part (I named it scoop) is invalid.  Somewhere in its creation something was scaled.

The current matrix is:

(matrix3 [1,0,0] [0,1,0] [0,0,3.14987] [-76.22,0,24.6385])

The first three vectors of the matrix should be unit vectors. Obviously the 3rd (Z) vector is not.  It should be [0,0,1] not [0,0,3.14987].  I have tried resetting the Transform but that did not fix the problem.  I cannot move forward until this is addressed.

[sakura13]

Ok i will rebuild it wait few mins, sry but i dont know what that is -.- and how can i check it do i need to rebuild anything?

[sakura13]

So I remodeld anything the old shovel is still inside and the new one is grouped, the modifers like shell and so  on is still there I think its better like that.

[leeminardi]

Please post a 2021 version of "remodeled".

[sakura13]

Strange I thought it was 2021 I hope all is fine now

[leeminardi]

I've made good progress.  I don't have the time right now to explain much but please take a look at the attached file.  You can select Dummy001 and move it in X and the scoop (yellow) will roll back as it should.  The end of the chain that attached to yellow is labeled PT_1.  It stays fixed relative to the scoop object. The tangent point to the yellow roller is Pt_2.  Its position is a function of scoop's roll angle and the location of the tangent point to the back roller.  The calculation for Pt_2 is in its position script (note, I end a label with "w" if it is world coordinates).

rA = 15.0
rB = 4.0
CenPtAW = CenPtA * ScoopT * CartT
CenPtBW = CenPtB  * CartT
uAB = normalize(CenPtBW - CenPtAW)
-- calculate intersection of tangenl line with line passing
-- line PtAW PtBW
ptIW = CenPtBW + uAB * ((length(CenPtA - CenPtB) * rB/rA)/ (1.0 - rB/rA))
theta = atan(rA/length(CenPtAw - PtIW))
LAI = length(CenPtAW - PtIW)
LAtangI = sqrt(LAI^2 - rA^2)
v = uAB * (rotateYMatrix theta)  -- rotate uAB by theta about Y axis
p = PtIW - LAtangI * v

Here's the chain position when scoop is all the way forward.

...and rolled back.

I only create a few chain links but the bone should indicate their path when more are added.

I need to do some work on the termination of the chain on the back end. 

It looks like there is some interference when the scoop rolls way back.  The blue round bar seems to extend too far.

What do you think?

More later, gotta run.

[sakura13]

Really nice take your time all fine 🙂 I think its better I will wait until finish before I getting more confused -.- i will waiting and am curious about the result if its fine for you. But I saw one problem the shovel goes throught the car before it collides to spring back

If you check the attached file the rotation angle is completly different.

[sakura13]

But really interesting,i would never have thought of this, how can i learn this anyway how do i start with animations like this do you know any good tutorials so i can learn this as well? Sry I cant wait an checked out the file, the blue one its only extended to be inside to the wall, and more like it can be there. I missed some references todo it correct thats my problem.