I have find a better method to solve this problem. :)
Angle ratio.zip

And I hope you could add "Angle Ratio" and "Angle difference" commands in the "constrain" menu, just like "length ratio" and "length diffrerence" commands. These two commands are very useful for driving the "motor" turn many rounds in step dimension mode.

Originally posted by @zhulaojianke in #996 (comment)