Error Sensitivity Analysis Of 3-UPU Parallel Mechanism Affected By Multi-factor

The output performance of parallel mechanism is influenced by many factors.Due to the effect of various inaccuracy factors,the output performance of parallel mechanism will be changed,resulting in a certain deviation from the target performance.Usually,these original errors are random,and the effect of original errors on the performance of parallel mechanism is changed with the change of the position and orientation of the mechanism.The key problem is that it is difficult to find an index to measure accurately the effect of original errors on the performance of the mechanism.For the problem above,sensitivity analysis of each source error to the output performance of parallel robot is adopted in this paper,aimed at finding access to the engineering performance index of parallel mechanism.This helps in further research and the design of parallel manipulators and provide theoretical basis for the application of them.In this paper,sensitivity analysis is used for the 3-UPU parallel mechanism.According to the D-H parameters of the mechanism,the transformation matrix from the base to the moving platform is derived,and the kinematic equation is established.Then,based on the principle of micro motion of robot,the error model including the manufacturing error and motion pair error is developed.According to the inverse kinematic solution of the mechanism,the input errors of different orders of magnitude is set.Sensitivity analysis along path is adopted to describe the contribution of each working conditions to the total position and orientation error of the mechanism affected by various error sources.According to the positive and negative properties of the platform's position and orientation errors,the sensitivity analysis is presented to describe the contribution of each error component to the performance of the mechanism.Furthermore,the sensitivity parameters are defined as two forms respectively,and sensitivity analysis is used to investigate the contribution of each working conditions on accuracy.The simulation results indicate that mechanism accuracy is not only affected by the error sources,but also closely related to the direction of motion.