A robot manipulator handling a heavy weight requires high-capacity motors and speed reducers, which increases the cost of a robot and the risk of injury when a human worker is in collaboration with a robot. To cope with this problem, we propose a collaborative manipulator equipped with a counterbalance mechanism which compensates mechanically for a gravitational torque due to the robot mass. The prototype of the manipulator was designed on the basis of a four-bar linkage structure which contains active and passive pitch joints. Experimental performance evaluation shows that the proposed robot works effectively as a collaborative robot.

• 송재복(Mechanical Engineering, Korea University, Anam- Dong, Sungbuk-Gu, Seoul, Korea) | Jae Bok Song
• 송승우(1Mechanical Engineering, Korea University) | Seung Woo Song