Multibody model and simulation of a statically balanced Parallel Kinematics Machine

The study deals with the compensation of gravity loads in closed-loop mechanisms as a possible strategy for enhancing their working performance. This work focuses on the Orthoglide 5-axis, a prototypal parallel robot for milling operation characterized by linear-delta architecture, and its statically balanced variant, previously derived by the authors. The suitability of the adopted balancing approach is assessed by means of numerical simulations. Kinetostatic analyses are performed for evaluating the operation of both the unbalanced and the statically balanced mechanisms during the execution of reference trajectories and common machining tasks. Then, a sensitivity analysis is carried out to test the robustness of the proposed balancing solution when discrepancies between the actual and the nominal values of the balancing parameters occur. The results of simulations prove the effectiveness of the balancing solution and a significant enhancement of the mechanism energy efficiency provided by gravity compensation.