Static Balancing of a 2-dofs manipulator

This paper proposes a gravity compensator for a 2-dofs manipulator which can be operated in hemispherical work space. The gravity compensator comprises two 1-dof gravity compensators and a bevel differential. It is revealed from analyses of energy and torque that the proposed gravity compensator can perform static balancing completely. The gravity compensation of a 3-dofs manipulator is proposed. Experiments show that the 2-dofs compensator can counterbalance the gravitational torques effectively and can be operated in hemispherical work space.