Design And Analysis Of 3-DOF Parallel Manipulator For Force-controlled End-effector Module

With the development of industrial robotics,manufacturing begins to use industrial robots to complete the tasks of some surface processing and post-processing with continuous contact,e.g.,deburring,and polishing,etc..To complete the highquality processing tasks with continuous contact not only needs the tool to implement the force control along the normal direction of the surface,but also to achieve movements in other directions.However,the existing industrial robots generally do not have the force-controlled function,which largely limits the application of robots in the area with continuous contact processing.Therefore,designing a kind of multi-DOF force-controlled end-effector modules has an important practical significance.In this work,a 3-legged Prismatic-Prismatic-Spherical(3-PPS)parallel manipulator is proposed for the development of a dexterous 3-DOF(?_x-?_y-Z)force-controlled end-effector module,where the two directions of rotation can accomplish a partial adjustment of the tool to achieve a more effective contact operation.This thesis focuses on the kinematic,workspace and dynamic modeling and analysis of 3-DOF parallel manipulator as a force-controlled end-effector module:Kinematic Analysis of the Manipulator: as the 3-PPS parallel manipulator has a unique kinematic characteristics,i.e.,zero-torsion rotations,its orientation can be always represented by a rotation about an axis fall on the x-y plane of the reference coordinate frame.Utilizing such a kinematic equivalence,the kinematic design issues,such as displacement,singularity,and workspace analyses,are significantly simplified.In addition,to generalize the kinematic analysis algorithms for design optimization,the passive prismatic joint in each leg is placed with a tilting angle with respect to the horizontal plane.Workspace Analysis of the Manipulator: utilizing the inverse displacement analysis algorithm for workspace elements detection,the resultant workplace based on the proposed kinematic design parameters is shown as visualization scheme.Due to the nonlinear mapping,a new method is introduced accurately when computing the orientation workspace from the parametric domains.This method provides an important basis for the synthetical dimension analysis.Dynamic Analysis of the Manipulator: Based on Newton-Euler method,the dynamics equations of the parallel manipulator are built up to study the dynamics performance of the 3-PPS parallel manipulator.Utilizing the algorithms of the simulation,the dynamic performance of the 3-PPS parallel manipulator with the different angle ?.In summary,the research work of this thesis provides the basic theory for the design analysis of a force-controlled end-effector module.