# Articulated configuration

I'm reading Theory of Applied Robotics, 2nd edition by Jazar. The author states that articulated configuration has the following form: $$R \vdash R \perp R$$ where $$R$$ stands for revolute joint, $$\vdash$$ represents that 2 adjacent joint axes are orthogonal (intersect at right angle) and $$\perp$$ represents that 2 adjacent joint axes are perpendicular (they close right angle with common normal). The example of articulated configuration is given in the image

So by looking at the image axes $$z_1$$ and $$z_2$$ are supposed to be perpendicular but they look parallel to me. What am I missing ?

Seems that the book has an error. You are right, they should correct that.

In the drawing it can be seen that those two z-axis are indeed parallel. I recommend that you considered them parallel and try to draw them to see that it fits with the image.

• Thanks for your answer jdios, but we are looking for comprehensive answers that provide some explanation and context. Very short answers cannot do this, so if you edit your answer to explain why it is right, ideally with citations people may find it more useful. Note that answers which don't include explanations may be removed. – Mark Booth Nov 28 '19 at 11:06