Denavit-Hartenberg Reference Frame Layout

This video demonstrates use of the Denavit-Hartenberg convention for defining the reference frames of a kinematic chain.

In short, the z-axis for each joint is placed along its axis of motion, and then the x-axes are placed along the common normals between these z-axes. Then four parameters are used to specify the transformation between each of these frames:
• d - the "depth" along the previous joint's z axis
• θ (theta) - the rotation about the previous z (the angle between the common normal and the previous x axis)
• r - the radius of the new origin about the previous z (the length of the common normal)
• α (alpha) - the rotation about the new x axis (the common normal) to align the old z to the new z.

See also the Tekkotsu kinematics page, with numerical examples, tools, and links to download HD. http://www.tekkotsu.org/Kinematics.html

• Category

  Science & Technology

[黃 兆民]

Is X1=Z0 cross Z1 or X1=Z1 cross Z0?

Are both directions ok?

[TekkotsuRobotics]

Both directions are OK, as long as you flip the sign on the associated 'r' parameter: a × b = -( b × a )

In other words, you have two choices for the direction of each x vector: one results in a positive r, the other results in a negative r.  (If z₀ and z₁ intersect, then r₁ is 0 so this is arbitrary)

Neither choice of (z₀ × z₁) vs. (z₁ × z₀) will yield positive r₁ for all configurations, so if you want to enforce a positive r you have to check and flip signs as needed.

[mavenuparker]

Awesome......I understood DH Notation :)

[muditmittalyou]

Really awesome......Great animation!!!

[Stephan Botes]

this is awesome.

[3anthos]

AMAZING!!! THANK YOU

[hkams]

Wonderful!!!!!!!!!!!!!!!!!!!!!­!!!!!!

[kemi242]

Thanks. I'm studying for an exam, and this helped make it clear.

[sahil rupani]

You saved my grace... like literally bro... I would have damn near flunked my paper cause i simply couldn't visualise it... Whoever you are you rock...

P.S. I wouldn't be surprised if it was Denavit himself who realised he needed to make a video to explain himself...

[thecaliforniabear]

This was explained too fast. Not for beginner.

[Arif İçke]

Thanks for the effort!

[MrGroakley]

Why are conjoined twins turning 16 a related video?

[aaronsnoswell]

In traditional DH Convention, the X axis, not the Z axis, is on the axis of rotation.