I have a few questions about controlling robot arm motion. I see that some have used Dynomotion KFLOP and other CNC motion controllers to control arms. Some have used Rumba board as well as several thousand dollar boards. But why don't we all just use ROS? What are the main benefits these boards give? AFAIK neither the KFLOP or Rumba allow realtime control. How come people invest (time/money) into these boards rather than ROS?