Abstract:Based on the widely used advantages of low degree of freedom parallel mechanisms (PM), a new-type three translation one rotation (3T1R) parallel mechanism was proposed, which had the characteristics of simple configuration, symmetrical structure, and high positioning accuracy. It can be applied to small-scale precision operations, as well as large-scale transportation, sorting, and spraying major industrial fields. Based on the topology analysis theory of orientation characteristic equation, the azimuth feature set of position and orientation characteristic (POC) was obtained, and the type and number of degrees of freedom (DOF) of the parallel mechanism were analyzed and verified. A kinematic model was established based on the closed-loop vector method, and the rationality of kinematics was verified through a positional forward and inverse solution example and the results indicated that the kinematic model was completely correct. The reachable workspace’s three-dimensional point cloud picture of the 3T1R parallel mechanism was analyzed by using the limit boundary search method based on the position inverse solution equation. A velocity Jacobian matrix was established through velocity analysis, and based on it, the positioning accuracy and operability performance indicators of the mechanism were analyzed. The PCA/PSO algorithm was used to optimize the design of the reachable workspace, positioning accuracy and operability as three performance indicators, and the optimization results were compared and analyzed. The final optimized reachable workspace volume was increased from 0.2933m3 to 0.4231m3, the positioning accuracy error amplification factor was decreased from 15.5044 to 4.4308, and the operability index was decreased from 9.7027 to 1.3996.
