On the design of a statically balanced serial robot using remote counterweights

This paper presents a 7-DOF partially statically balanced robot that has been developed for physical human robot interaction. The gravity compensation technique uses remote counterweights connected to the robot via a low-pressure hydraulic transmission. Low-friction diaphragm cylinders are used in order to provide very low residual friction. A two-stage balancing bench allows using a unique moving counterweight to adapt the balancing to a payload of up to 10 kg, that is the maximal payload of the gripper. The robot can be easily moved passively while being capable of physically assisting humans in the performance of tasks.