| Parallel robots are structurally linked by two or more links and moving platform to form closed-loop kinematic chains.Which have the advantages of high accuracy,high stiffness and high load-carrying capacity.They are widely used in machine tools,micro-manipulation robots,motion simulators,high-speed robots and other fields,among which Gough.Stewart mechanism is the most widely used representative mechanism.Compared with the widely used 6-DOF parallel robot,the lower-mobility parallel robot refers to the 3-5 DOF parallel robot,which is economical,simple,reliable,easy to control and has bright application prospects.In this paper,the kinematics and stiffness of the 2-UPR-PRU mechanism are analyzed,and the corresponding size-optimization is carried out based on these analyses.The main contents are as follows:(1)Introduce the mechanism and establish the coordinate system to analyze the DOF of the mechanism in the initial and general configuration by the screw theory;analyze the position of the end of the moving platform of the mechanism by the closed-loop vector method and verify its correctness(2)Doing Velocity analysis and singularity analysis of 2-UPR-PRU mechanism on the basis position analysis.and then reachability/regular workspace calculation of mechanism is carried out on this basis.(3)Analyze the global motion/force transfer performance index and virtual work stiffness index of 2-UPR-PRU mechanism are analyzed.(4)Based on the global motion/force transfer performance index,virtual work stiffness index and regular workspace volume,the size of the mechanism is optimized.(5)Based on the original design parameters,the main components of 2-UPR-PRU mechanism prototype and the assembly parts of each branch are selected and assembled,including the selection of P-pair sliding table and motor of each branch,the bearing selection and assembly method at the joint of each branch and fixed/moving platform,etc. |
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