... Hai Nguyen1 and Jee-Hwan Ryu2 1School of Mechanical Engineering, Korea University of Technology and Education, Cheonan, Korea (E-mail: bmnhy2003@gmail.com) 2School of Mechanical Engineering, ... operation; (b): distance measurement using four distance sensors and feedback force implementation using a DC motor. The essential components of an OBW system are distance sensors associated ... implemented in many fields such as robotics, factory automation, automobiles and so on [6], [7], [8]. The proposed OBW system is a system that enables the operator to concentrate on the tasks and accomplish...