I have just started working on this SCARA robot and find it very interesting.
I have all the stepper motors working and now I'm trying to figure out how many steps make a degree of movement. This is all about the math or geometry.
So the reach of the SCARA arm is about 200mm so the process is to determine how many steps equals 90 degrees for both the arm and the elbow.
Once I have that I can use the law of cosines to position the arm any where on the grid.