Singular Configuration Analysis Of Less-Dof Parallel Manipulator With Central Constraint Limb

With the development of parallel robot technology, less-DOF parallel robot becomes the research foucus of mechanism field, due to its advantages of less-limbs, simple-control, easy-manufacture and low cost. The theory of singular configuration is a key part of parallel manipulator theory. Robot's movement, load, control and accuracy have close relationship with singular configuration. It is extremely necessary to have deep research of parallel manipulator's singular characteristic, so as to eliminate the affect of singular configuration, enhance the capability of parallel manipulator, and promote its development of utility and production. Based on the research of domestic and foreign achievements, singular congiguration of two kinds of less-DOF parallel manipulators, which contain central constraint limbs, is researched by both analytics and CAD varation geometric approach in this paper.Firstly, several 3 or 4 DOFs parallel manipulators which contain central constraint limb are constructed via CAD varation geometric approach: constraint, parameter constraint and parameter driving technology. Secondly, positive and negative soulutions of 3UPS+UP,3UPS+UPR and 4SPS+PS position simulate mechanism are testiyied through analytics approach. By computing the translational and rotational Jacobian matrix standing for the moving platform's liner and angel velocities, which have direct coupling relationship with independent output velocity vector, mixed n×n Jacobian of n DOF parallel manipulator is gained. Velocity simulate mechanism is also contructed, and the postures, happening when velocity changes excessively, are searched by velocity simulate approach. The paramters about the postures are iuputed into the mixed Jacobian, velocity and Jacobian's determination at these postures are resolved by analytics, so as to make comparation with singular configuration gained by simulate method. Thirdly, computer program is made, and the condition how singular configuration of two kind mechanism distributes in workspace, is selected by searhing each point in area. Finally, velocity Jacobian is simulated in velocity simulates mechanism, and singular configuration is anlyzed throgu solving Jacobian's determination.