Development of an Elastically Compensated UPS-Type Constant-Force Generator for the Static Balancing of Spatial Parallel Mechanisms

Implementing static balancing is a viable strategy to enhance the performance of manipulators, particularly in terms of energy efficiency. This work presents a novel solution for the gravity compensation of parallel robots featuring UPS-legs, such as Gough-Stewart platforms, which represent a wide class of closed-loop mechanisms. By installing proper balancing components, namely four tension springs and an auxiliary linkage, the leg can generate, at its tip, a general force that is constant in both magnitude and direction. The parameters characterizing the proposed arrangement of balancing components are analytically determined by imposing that the total potential energy of the leg remains constant for any assumable configuration. The effectiveness of the proposed solution is successfully verified by means of numerical simulations performed with a commercial multibody software (MSC Adams™).