Study On Error Sensibility Of 3-UPU Parallel Manipulator

The symmetrical lower-mobility parallel mechanism, which characterizes identical limbs, symmetrical arrangement and isotropy, has great potentials in practical application. The paper has synthesized the errors of 3-dof and 4-dof 3-UPU parallel manipulators.A new method has been presented,which is about space coordinates transformation and vector transformation.The pose error resulting from static errors has been analyzed.The ideal and actual spatial pose transformate matrixes have been established.With the method of numerical analysis, the paper calculated and analyzed the forward pose solutions of the 3-UPU parallel manipulators. From two aspects, analyzed the robot pose errors due to the static errors, Firstly, the error is anchanged, analyzed changes of robot errors over time , received the end of operation of the robot's position and orientation errors; Secondly, use the related concepts of the probability distribution o, analyze the robot pose errors' changes due to the various error sources on the robot,and obtained some laws of error distribution.The paper has analyzed the 3-dof 3-UPU parallel manipulator and the 4-dof 3-UPU parallel manipulator relatively.Finally,we have got the following conclusions:1. 4-dof 3-UPUparallel manipulator under the action of the various error sources,the rotation error around the Z-axis has high sensitivity.It's very easy to bound out of the rotation around Z-axis,and degenerate into a 3-dof pure translate 3-UPU parallel manipulator.2. 3-dof 3-UPU parallel manipulator,under the action of the various error sources,the rotation error around the Z-axis is little and the sensitivity is very low.the constraints of the Z-axis rotation is stability.The rotation error around the Z-axis is effected little by the error sources.