Inverse kinematics robotic arm - last link not moving

[Hendrik]

Hey all,

after i did the inverse kinematics tutorial on my robotic arm, i figured out that i have a problem.
I can move the robotic arm by moving the target dummy around but the last link (on which the tip dummy is attached) is only moving relatively to the previous link.

So the last link always remains in the same attitude relative to the floor or the initial, stoved, configuration.

That means that if i want to stretch the robotic arm completely i miss some distance because the last link is not "stretching".

Any idea of what i could have done wrong?

[coppelia]

Hello,

make sure that all of your joints are in IK mode, and that the base of your IK element is the base of the robot (or world).
Easiest would be to post your scene.

Cheers

[Hendrik]

Hey,

I tried that but i fear the problem is somewhere else.
I uploaded the scene here:

http://1drv.ms/1HQ8GQZ

Maybe its clearer to understand the problem when looking at it. So the problem that i have is that the gripper always stays in the same pose...

[coppelia]

As far as I can tell, the arm behaves correctly according to the IK: all 7 joints are used during IK calculation. Or did I misunderstand something?
One thing that is not good, is that you should have the tip and target overlap at simulation start, otherwise your mechanism will jiggle at the beginning, and sometimes never find a resting configuration.

You can fine-tune the IK by adjusting the IK resolution weight of the individual joints.

Cheers