As a custom automation Design House, we utilize A LOT of 6-Axis and 4-Axis (SCARA) robots. Generally, the SCARA's don't give me too many problems in an assembly, however, I would say that 99% of the time, When I insert a 6-Axis Robot (Epson, Fanuc, or ABB supplied models which I then convert and apply joint constraints to), I will will get constraint errors when opening a higher level assembly. The Robots must be flexible as we have to be able to freely move them and put them in a significant number of positional reps. As a rule, I use an insert constraint on each joint, and then an Angle Constraint (Explicit Vector Reference Method). I usually suppress the angle constraint until I need to apply a Pos Rep in an upper level assembly.
