Rigging a hose between two objects

[alphajoe]

I need a little help here. I am modelling a machine that has a moving part that has a hose running from it to a stationary part elsewhere on the machine. I need both ends of the hose to be a little stiff so that when the part moves, the hose doesn't rotate around the bound skeleton and interpenetrate the part itself. I can get one end to work perfectly by starting the IK handle at a joint before it enters the part, but the other end of the skeleton rotates in accordance to the joint orientation of it's parents and causes the end bone to rotate outside of the geometry.

I know this probably sounds confusing without actually seeing the setup, but does anyone have any idea how I can get this to work?

[tfall]

I learned a technique for rigging a character's spine that might help you. It used IK spline IK but allowed for independent rotations on each end.

Instead of using the twist and roll attributes of the IK controller, add clusters for each of the control points of the spline IK curve. Then parent the clusters to the control object on either end of the joint chain. Depending on where the clusters are placed, you can get more or less stiffness. To get the twisting, write an expression that distributes the rotation of each control object down the chain (effect is reduced the farther away it is).

---

float $A = hipsCTRL.rotateY;
float $B = chestCTRL.rotateY;

cl_spinebJNT.rotateX = ($A * 0.9) + ($B * 0.1);
cl_spinecJNT.rotateX = ($A * 0.7) + ($B * 0.3);
cl_spinedJNT.rotateX = ($A * 0.5) + ($B * 0.5);
cl_spineeJNT.rotateX = ($A * 0.3) + ($B * 0.7);
cl_spinefJNT.rotateX = ($A * 0.1) + ($B * 0.9);

---

You could add some intermediate controls the middle of the chain as well, such as if the hose was long, to add more flexing or bounciness.

• Terry