Research on Fuselage Section Docking Method Based on 4-PPPS Parallel Mechanism
The distributed 4-PPPS parallel mechanism based on the composition of multiple NC locators is used to realize the auto-matic and accurate docking of the cabin.The redundant driving can improve the mechanism loading capacity and make the distribution of driving force more balanced.However,there is a high-dimensional zero space in the Riemannian manifold composed of redundant sys-tems.The nonlinear equations of coordinated distribution have multiple constraints and are not positive-definite,and improper distribu-tion will generate excessive stress and strain.In order to achieve the accuracy of kinematics and the steady state coordination of dynamics in the docking process at the same time,based on the screw theory,the rigid body motion was decomposed into rotation and translation around any axis,and the kinematics model was established to determine the joint drive.The dynamic models under non redundant and redundant conditions were derived,and the model parameters that affected the docking motion characteristics,such as cabin angular ve-locity and angular acceleration,were solved.A method was proposed to optimize the distribution of the driving force of docking motion with the goal of minimizing the two norm of force.The position and attitude trajectory was described by a 5 degree polynomial,and the optimal time was approximated by the golden section method.Finally,comparative simulation of non-redundant and redundant drives was carried out.The docking process is accurate and stable,which proves the correctness and feasibility of this method.
aircraft dockingparallel redundant mechanismredundant system kinematicsdynamic optimization
万方数据
维普
