Gravity Balancing of a Spatial Articulated Manipulator Based on a New Spring Mechanism

Based on the theory of conservation of potential energy, design of a gravity-balancing spatial articulated manipulator by the use of a proposed spring mechanism is presented. Since the gravitational potential energy of the mass system of a spatial articulated manipulator of n links depends only on the orientation of each link within the system, the entire manipulator can then be considered to be equivalent to an array of n degenerated ground-adjacent links in the aspect of the potential energy. Moreover, since the gravitational potential energy of a rotary link moving in a vertical plane is a trigonometric function and the Scotch york mechanism is also a well-known harmonic motion generator, a new spring mechanism composed of a Scotch york, a compression spring, and a gear pair is used to balance the gravitational potential energy of each degenerated link. With a built-in spring mechanism embedded on each joint of the articulated manipulator, the entire spatial articulated manipulator maintains can be in equilibrium at all configurations, which is verified by the simulation of the system modeled in a commercial software Pro-Engineer. The prototyping of a practical system will be implemented in the near future.