I work on this project for which we have a robot arm (6 servos), a camera attached to its extremity which tracks a physical object, and we wish to set up the experiment in Blender. We used an armature to model the robot, and rotations are blocked to mimic the real robot.

We want to be able to provide the position of the camera (which targets the object) and we want to obtain from that the rotation of the servos at each extremity of the bones of the armature.

The first problem we have is to constrain the camera to the last bone (to which it is attached), but at the same time we want it to target an object. We tried to use parenting, copy location/rotation, but in the end the camera keeps moving (and ignoring at least one of the constraints)

Do you have any idea of how we can fix that?

Once this problem is solved, I hope we can extract the kinematics of the robot.

link: blend file


-- Matt

  • $\begingroup$ I see no problems in your setup, can you provide a file, or screenshots? $\endgroup$ – Crantisz Nov 14 '18 at 13:58
  • $\begingroup$ Hi @Crantisz, I edited the question with the file and here's where I'm stuck: - I want the "cam" to track the "target" - I want the bone camera to be orthogonal to the bone "wrist angle" (by design), so that only "wrist angle" rotates. Any idea? Thanks! $\endgroup$ – MatthieuV Nov 27 '18 at 14:09
  • $\begingroup$ I don't see any changes in the question $\endgroup$ – Crantisz Nov 27 '18 at 14:14
  • $\begingroup$ It should be ok now $\endgroup$ – MatthieuV Nov 27 '18 at 14:17
  • $\begingroup$ any help @Crantisz ? $\endgroup$ – MatthieuV Dec 3 '18 at 12:12

As I understand your problem here the my solution.

Try to do this setup from different way.

  1. Add a "rotation" bone, witch will control hole system in z rotation.

    enter image description here

  2. next setup "camera direction" bone, lock its moving in x axis and parent it to the "rotation" bone. I use IK in both cases.

    enter image description here

  3. When you just need to setup your bones with correct lengths and axis locks. On last bone make IK constraint to the "camera direction" bone with rotation option enabled

    enter image description here

  • $\begingroup$ Thanks @Crantisz, I had a quick look and it seems to be doing what I need. $\endgroup$ – MatthieuV Dec 4 '18 at 20:58

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