Design and Analysis of an Inverted XY-3RPS Hybrid Mechanism for Polishing of Complex Surface

Aims: An inverted XY-3-RPS hybrid mechanism was designed to apply ultraviolet-induced nano-particle colloid jet machining to polish the complex surface. Background: The hybrid mechanism has been widely used in the ultra-precision polishing field for installing different polishing tools on the moving platform to meet different machining requirements because of its wide working space, good dynamic performance and large bearing capacity. Objective: The main objective of this study is to establish an inverted XY-3-RPS hybrid mechanism for UV-induced nanoparticle colloid jet machining, to realize the ultra-precision polishing of complex surfaces by UV-induced nanoparticle colloid jet machining. Methods: The three-dimensional model of the inverted XY-3-RPS hybrid mechanism was established, and the kinematics and dynamics were analyzed. The Jacobian velocity matrix of the inverted XY-3- RPS hybrid mechanism is derived by vector construction and differential methods, and the dexterity index under different proportional parameters is optimized and simulated. The output Jacobian matrix and stiffness matrix are obtained using the virtual work principle, and their static analysis is carried out. Based on Lagrange dynamics theory, the dynamic mathematical model of the inverted XY-3-RPS hybrid mechanism is established, and its kinematics is verified by software joint simulation. Through dynamic simulation, the variation curves of motion, force and kinetic energy of the mechanism are obtained, which provides a theoretical basis for applying the hybrid mechanism in complex curved surface polishing. Results: The analysis shows that it has the best dexterity index when the ratio of moving and the fixed platform is 2:1. The kinematic simulation results show that the hybrid mechanism moves reliably under the given trajectory. The dynamic simulation results show that the force analysis of each kinematic pair and the kinetic energy change curve of each part changes smoothly, and the dynamic performance is stable under different trajectories. Conclusion: The parameter design and structural design of the inverted XY-3-RPS hybrid mechanism meet the requirements of ultra-precision polishing of complex surfaces.