0
$\begingroup$

I am trying to set up a generalized approach to generate DH parameters for my simulated robot arms, but I am having trouble setting up the frames. To find the X axis of each joint I read that I have to find a line orthogonal to both Z axes of the previous and current joint. e.g. as explained in this video around 0:40 https://www.youtube.com/watch?v=rA9tm0gTln8

However, in some cases I find that a line orthogonal to both Z axes does not seem to exist. So how do I then determine the X-axis direction of subsequent joints. Are there configurations for which DH-parameters simply do not exist? or is there some other rule tied to this? Or does this orthogonal line exist somewhere but I'm simply failing to find it? I can't find my specific case online. I have enclosed a picture with the two Z axes drawn in the axis of revolution for 2 joints. the Z axes are not intersecting anywhere, not parallel and not perpendicular.two joints with Z axes pictured in axis of rotation

Improve this question
$\endgroup$
1
  • $\begingroup$ DH is not unique. Which one you are using? $\endgroup$
    – CroCo
    Jul 13, 2022 at 18:04

2 Answers 2

Reset to default
2
$\begingroup$

Given two linearly independent (read: not parallel) vectors, you can always find a vector which is perpendicular to both of them using the cross product: https://en.wikipedia.org/wiki/Cross_product.

Improve this answer
$\endgroup$
0
$\begingroup$

Absolutely. Depending on which version of D-H you are using, look at the $d$ and $r$ terms to accommodate the offsets.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.