Gravity Compensation of Delta Parallel Robot Using a Gear-Spring Mechanism

This paper presents a design concept for the gravity compensation of the renowned Delta parallel robot. The design is constructed by using three gear-spring modules, each being installed on the proximal link of each leg of the robot. This implementation can allow the balancing design to merely request a relatively small assembly space on the robot, thereby avoiding mechanical interference between the supplemental structures and robot links during operation. The spring design is realized by an analytical approximation to perfect balancing. A design example for an industrial Delta robot, namely FANUC M-3iA/12H, is also given. It is shown that the studied robot can theoretically demonstrate a 41.4% total motor torque reduction during a pick-and-place operation under a 10-kg load of the moving platform.