IK inconvenient

(Thargonine) #1

I’m new in Bongo and im having a lot of problems lately.
I have been working an animation of a robot with Ik chain constrains , i follow the instructions of the example of the official page, the first exercise i made it, and wirk perfectly, the i try to do it again with some modification in the model and did’t work.
I really don’t know what i did wrong this time, so if any can help me to understand what i can do, i would aprecite a lot.
The idea its that the point that is on the robot can follow the other point.

(Luc Adriaenssen) #2

Could you please post the faulty model so that we can have a look.


(Thargonine) #3

ik prob.3dm (17.4 MB)

(Luc Adriaenssen) #4


The malfunction is because the main portion of the robot isn’t part of the IK chain.

Your model contains 2 chains. The first is building up from the object ‘Base’ until ‘extructor’. Although the element are Joints (Hinges) there is no constraint to turn it into a IK-chain. The second chain contains ‘boquilla’ and its child ‘Object 7’. Since ‘Object 7’ is constrained the chain functions as IK but only as far as ‘boquilla’ is concerned.

When you make ‘boquilla’ child of ‘extructor’ the complete robot is put into action in an effort to solve the constraint
ik prob 001.3dm (10.4 MB)

Allow me to comment further, since things still don’t seem to go right.

That is because ‘ARM’ should be child of ’Base’, since the arm is attached to the base. The functioning of the hydraulic cylinder ‘maq’ and ‘none‘ is a another piece of cake.

Furhter ‘extructor’ and ‘boquilla’ are both hinging around the same axis, so ‘boquilla’ can better be simply attached to ‘extructor’ (“None” in the Constraint and Joint Properties)
ik prob 002.3dm (10.5 MB)

Finally the ‘ARM’ is swinging around a bit too much. Setting the Limits for the hinge to Minus 0° and Maximum 90° will tame it.
Something similar has to done with ‘rotten 2’ to prevent it from passing over.
ik prob 003.3dm (10.5 MB)


PS. In your model the ‘model units’ (Document properties) is set to ‘Meters’. Your robot is about 2 meters high. In Bongo’s document Properties the Pivot size is set to 5 units , thus 5 meters. The IK decoration is sized accordingly; that’s why they look so big. Changing the pivot size unfortunately doesn’t resizes the decoration. Scaling the model won’t either. I guess you’re stuck with the gigantic decorations.

PPS In the models in attachment I deleted all the irrelevant layers (and Block) to slim down the file sizes.

(Thargonine) #5

oh… ok ok thank you so much, i’m gonna try to correct it.