denavit hartenberg table for my 5 DOF robotic arm

Hello everyone!
I'm having trouble finding the denavit hartenberg matrix for a 5 DOF robotic arm. The schematic of the robot is on the following link (it was drawn in
solidworks): http://postimage.org/image/5wfe5j4fh/ . I need the denavit hartenberg table so I can perform simulations on matlab.
Everything works fine until i reach join n4, where it has to rotate around it self, and I am absolutely lost, no idea how to make it rotate the way it must on MatLab.
Here is how i thought the DH table would look like:
Th* L d alfa 0 0 L1 pi/2 0 L2 0 0 0 L3 0 pi/2 0 L4 0 pi/2 0 L5 0 0
*All Th values are variable.
Every joint rotates as it should, except joint number 4, wich has to rotate around itself
Any ideas?
Thank you very much.
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On 11/30/2012 12:51 PM, Median wrote:

That looks pretty much like an articulated planar arm with a spherical wrist. I've seen -pi/2 then +pi/2 in the wrist; but that really doesn't change anything. Maybe you had the last length in the wrong spot?
Th* L d alfa 0 0 L1 pi/2 0 L2 0 0 0 L3 0 -pi/2 0 L4 0 pi/2 0 0 L5 0
- Daniel
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