The DH parameters of the UR5

[ccheng292]

I used the DH extract tool for UR5 in V-rep. I get the following result:
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Between 'UR5_joint1#0' and 'UR5_joint2#0':
d=0.0661
theta=0.1
a=0.0050
alpha=-90.0
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But for UR5, the standard DH parametersis "d=0.089159, a=0, alpha=pi/2 ", the standard DH parameters is "d=0.089159, a=0, alpha=0", Let's just talk about alpha, why the alpha got from extractor is -pi/2?

[SevenTRI]

Excuse me, have you solved it?