currently i am programming for a robotic simulation. I have a Endeffector which aproaches a target, on the way to the target is an Obstacle. Now i redirect my Endeffector, so that it does not hit the target.

When i want to do the same for the whole arm i want to push the arm away from the Obstacle as well. Now i have it working so far that i can redirect the arm. But my calculation for the Jacobian seems to be faulty.

For my setup, and what i need for that.

I have a robotic arm, 7DOF. Let $x_0$ be the closest point on the arm to the obstacle. And $J_0$ the corresponding Jacobian. Also i have given the following term: $\dot{x_0} = J_0 * \dot{\theta}$

$\theta$ are my joint angles. I can calculate the Jacobian for the EndEffector, but do not know on how to calculate it for a point ob the arm.

Does anybody have an Idea on how to calculate the corresponding Jacobian.



1 Answer 1


If the point is on some intermediate link, you can recompute the Jacobian with only the joints leading up to that link. See this post or your favorite robotics textbook for how to create the Jacobian.

  • $\begingroup$ Thanks for your answer, it is a point somewhere on the arm, but not necesserily a joint. Might be in between two joints on the arm. Does this approach still work then? $\endgroup$
    – Lenny
    Commented Apr 23, 2015 at 9:47
  • $\begingroup$ Yes, your last "link" will be the transform from the last joint of importance to your desired point, even if it is not on the arm. $\endgroup$
    – Ben
    Commented Apr 23, 2015 at 17:05

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