The Design And Analysis Of Spatial 4-R(4S) Parallel Mechanism

Compared with serial mechanism, parallel mechanism with the high precision, strong carrying capacity and lower movement inertia, has become a hotspot of mechanism research recently. Compared with the general parallel mechanism, the parallel mechanism with actuation redundancy has fewer singularity loci, better flexibility and lower energy consumption, so it has more advantages in the case of high speed and overloaded situation. On the base of the original Delta parallel mechanism, the spatial 4-R(4S) parallel mechanism with actuation redundancy is improved. The kinematic analysis, the dynamic analysis, the performance analysis and the dimensional synthesis are studied. The specific content is as follows:On the base of the original Delta parallel mechanism, the spatial 4-R(4S) parallel mechanism with actuation redundancy is improved that can realise three-dimensional translation. The structure characteristic of the spatial 4-R(4S) parallel mechanism is introduced and the degree of freedom of the parallel mechanism is analyzed based on screw theory. The position, velocity and acceleration equations of the 4-R(4S) parallel mechanism are given. The workspace of the 4-R(4S) parallel mechanism is solved based on the position equation using numerical method. The singularity loci of the 4-R(4S) parallel mechanism and Delta parallel mechanism was analysed using Gosselin singularity analysis. The singularity and dexterity of the spatial 4-R(4S) parallel mechanism and Delta parallel mechanism were analysed based on the manipulability using numerical method. The evaluation indices of kinematics performance is given and the kinematics isotropic of the 4-R(4S) parallel mechanism is analyzed based on the velocity ellipsoid.According to the Lagrange equation method, the dynamic model of spatial 4-R(4S)parallel mechanism is established. The coordination distribution of driving moment was finished. The evaluation indexes of dynamics performance is given and the dynamics isotropic of the 4-R(4S) parallel mechanism is analyzed based on the dynamics ellipsoid. Global kinematics condition indexes and Global dynamics condition indexes are established for the object functions. The dimension synthesis of the 4-R(4S) parallel mechanism is finished based on the improved non-dominated sorting genetic algorithm(NSGA-?) under the condition of constraint condition. The dimension synthesis aims at obtaining optimal mechanism parameters based on the indexes of kinematics and dynamics performance.