How to link spline ends to moving objects (hydraulic hose)?


#1

Hello,

can someone please help me on this topic: I need to animate a cylinder on a vehicle. To anmiate the cylinder is no problem but how can I make the ends of the hose react correctly? The hoses are made using Rhino history, a spline and an extrusion along path with a circle. I can move the ends of the spline by hand but that is very timeconsuming since it needs several keyframes to be somewhat “precise”.
Thanks a lot for any help!

Regards,
Tim




(Marika Almgren) #2

Tim,

Would it be possible for you to send us the model?
You can upload it using the following page:
http://www.rhino3d.com/upload

You can put marika.almgren@mcneel.com in as the recipient.


(Marika Almgren) #3

Thank you for the model!

The easiest way to fix your model is just to manually move the end and add more keyframes that way.

The other way to animate the hose would be to do it the way this cable pen was done using the IK feature:
http://download.mcneel.com/s3/mcneel/bongo/2.0/samples/en/BongoIKCablePen_v4.3dm

but that’s even more time consuming and the result is not as smooth as what you get when using morphing.


#4

Marika -
Interesting reply. I have a similar need.
Where could I go for some step-by-step how-2? What is “morphing” used in this context, and how does it work ? Does this apply to RH-4 or only to RH-5 ?
Thanks-
Charley.


#5

Also, I tried the referenced model, and it seems to apply to BONGO-2 on RH-4. I’m using BONGO-1 for reasons we’ve discussed previously. Is this ability not available in BONGO-1 ? If not, that’s fine, just need to know.
Thanks -
C.


(Marika Almgren) #6

Charley,

Morphing is a new feature in Bongo 2.0 and Bongo 2.0 works only in Rhino 5.


#7

Marika-
(and Tim293)

Ok, sounds fine. Morphing in BO-2 on RH-5. Cool. I’ll investigate when I return to efforts migrating forward from RH-4 to RH-5.

Here’s how I met the need using RH-4 and BO-1:
With HISTORY set to ALWAYS RECORD, I made a circle at each end of the centerline-curve of the tubing (using the circle around curve option), and one about the mid-point of the tubing. I then made each end-circle the “Daughter” of the component that each end of the tube was attached to. Using LOFT I created a “hose” that curved in a fairly close approximation of the centerline curve I used for the circles, and as described the arc of the hose. I was then able to animate the motion of the components, and the hose followed with no breaks in the motion. To recap: 3 circles, around a centerline arc, History, BONGO Parent/Child, LOFT, animate.

This was NOT “physically” accurate, but was a reasonable enough approximation to complete the animation and when rendered and compiled, the point of view was such that the difference was undetectable. IF you MUST take a CLOSE Look at the motion of the hose as your mechanism animates, (a very distinct possibility as hose motion IS a design consideration in these instances) this CAN be very closely approximated by discovering how the extents of the mechanism’s cycle-end positions affect the hose-under-pressure positions at the critical points in the motion cycle, find the least allowable extents position, and animate the mid-point circle of the lofted tube to that position at that point of the motion cycle, and back again. While AGAIN not PHYSICALLY “Accurate”, its an even closer approximation, that also has the added benefit of accuracy where its needed.

I’ve also used this approach when depicting Crane loft-lines and down-line, as well as ROV umbilicals, with good success. I find the combination of BASIC RH-4 and BO-1 to be a ROBUST, STABLE and POWERFUL platform. I look forward to exploring the additional features and benefits promised by the RH-5/BO-2 combination !

Good luck, and post back here with results? We ALL benefit from follow-ups and whether/how suggestions worked !

Thanks -
C.