Multi-DOF counterbalance mechanism for low-cost, safe and easy-usable robot arm

Recently, various types of robot arms have been developed due to the increasing needs of the robot in various fields. However, these robot arms are still too much expensive and dangerous since high capacity motors and gear reducers are used to provide sufficient torques to support the robot arm mass. This makes robot market still limited to industrial fields. To this end, we propose a novel counterbalance mechanism based on the spring-wire and a double parallelogram mechanism, which can completely cancel out the gravitational torques applied at each joint due to the robot mass. Thus the robot would need much smaller torques, which can be delivered by cheap and low capacity actuators. Furthermore, a 6-DOF counterbalance robot arm was built to demonstrate the performance of the proposed mechanism. Simulation and experimental results showed that the proposed mechanism had effectively decreased the torques required to operate the robot arm and thereby allowing the prospective use of low capacity motors and gear reducers for high performance robot arms.