I'm trying to apply modified DH parameters (from Craig's version) to Puma 560.
As per modified DH says,
And the robot Puma 560 with axes and frame are,
As per above sign convention, the sign of d2 and d3 should be negative. However, for the correct result, it seems that the sign of d2 should be positive.
My question is, should the sign here be positive and if yes, then doesn't it contradict the sign convention for above mentioned modified DH convention?