Hi all,

I am working on a simulation project of Motoman MA1900, I use Robotic Toolbox of Matlab to solve the problem but it says

"wrist is not spherical".

Then I realize that there's 30mm shift between the 6th axes and 4th axes, see the pic attached.

Please help. How can I solve the inverse kinematic of such kind of robot? Any suggestion or tip, thanks~