Research On Key Technology Of A 5-dof Hybrid Exe-m Robot

With the aid of the 863 Exemplary Project, to meet the demand for the manufacture of a novel Bars-Converging Joint used in the steel structure, the dissertation investigates into the design theory and method of the EXE-M robot—a novel 5-DOF hybrid reconfigurable robot possessing proprietary intellectual property rights. Research includes inverse position analysis, Jacobian matrix solution, dimensional synthesis, inverse dynamic analysis, servomotor parameters estimation and trajectory planning. The following work has been accomplished:1. Inverse position analysis and Jacobian matrix solution: According to the characteristics of the EXE-M robot, it is decomposed into 3-SPR parallel module and 2-DOF serial module. With three displacement variables, the former reveal inverse kinematic model has been developed by the Sylvester method, while the latter is proposed by the method of cyclic search and pure trajectory theory. The integrated Jacobian matrix of its parallel subsystem is simply formulated by the screw theory, and then the general Jacobian is constructed.2. Dimensional synthesis: To avoid the complexity of the forward solution, a simple solution to workspace of the 3-SPR parallel manipulator is constituted by using its CAD simulation mechanism. With the characteristics of the workspace of the mechanism and the relation between scale parameters, a integrated processability index is proposed which can balance the conflict between the scale average value and range. Then the dimensional synthesis of the parallel subsystem is considered as a two-parameters optimizing problem, which avoids the complexity of nonlinear programming including constraints, and the feasibility and simplicity of the method is verified experimentally.3. Inverse dynamic analysis and servomotor parameters estimation: Combining the branch-fixed secondary frame with the moving platform-fixed secondary frame, the decoupling mapping relation between the angular velocity and angular acceleration of branches and the velocity of the moving platform have been proposed, cleverly leading out the spin angular velocity and angular acceleration of three branches. Finally based on the inverse dynamic model, the speed rating, the power rating and torque of servomotor are estimated by the singular value of Jacobian matrix. The effectiveness of the approach has been verified using classic trajectory planning.4. Trajectory planning: The movement of the robot end-effector can be grouped into the spatial point-vector movement. A trajectory planning algorithms of time synchronization is proposed for any more-mobility hybrid mechanism, as well as the planning method for any space curvilinear motion. Using cubic splines function, the real-time trajectory programming in joint space mapped from the workspace is obtained further, which can guarantee the running stability of joints. At last, the effectiveness of the above-mentioned approaches has been verified by the simulation of joints machining.