Initial Design And Performance Analysis Of Planar 3-RRR Parallel Robots

Workforce occupies an important position in economic development.As China is steppinging into an aging society,only improving labor productivity can further support economic growth.As the key equipment for automated production,robots are used to assist or replace human work.Therefore,it is of great significance to improve the performance of robots and promote their application in society.Compared with serial robots,parallel manipulators own the advantages of high carrying capacity,high positioning accuracy,and good dynamic performance,thus being widely used in flight simulators,parallel machine tools,and high-speed pick-and-place devices.In order to promote the application of parallel robots,this work studied planar 3-RRR parallel manipulators in terms of kinematics,optimum platform design,kinematic performance analysis,force/motion transmission analysis,and the design of synchronously driven planar 3-RRR robots.The detailed work is given as follows:(1)A parameterized model of planar 3-RRR parallel manipulators was established to optimize the shapes of platforms,the base and the mobile platform.Workspace analysis was accomplished to find out the design parameters,which affect significantly the workspace.Based on vector algebra,the kinematics of this model was given with geometric meanings.Morever,the Jacobian matrix was constructed by using the three-dimensional screw system.(2)Based on the parametric model,global conditioning index was successfully applied to optimize the configuration of planar 3-RRR parallel manipulators,including both symmetrical topologies and non-symmetrical topologies.The parameters of some optimal configuration as well as the kinematic performance atlases were obtained.Singularities and local kinematic performance of a selected configuration were investigated.The performance sensitivity analysis was accomplished to reveal the platform parameters' influences on overall kinematic performance.(3)By utilizing the duality of motion and force spaces,a simple and systematical approach was formulated through the formalities of linear algebra so as to evaluate force/motion transmission performance of planar fully parallel manipulators,upon which an optimum design considering platform shape was carried out.The parameters of some optimal configuration as well as the transmission performance atlases were obtained.Singularities and local transmission performance of a selected configuration were investigated.The performance sensitivity analysis was accomplished to reveal the platform parameters' influences on overall transmission performance.(4)The planar 3-RRR mechanisms with synchronously driven actuators were investigated.The singular behviours of this mechanism were analyzed.An approach of motion synthesis for this single-dof mechanism with design variables amounting to 20 was proposed.A formula was derived from the analytical solutions of the path synthesis equation,upon which the design parameters could be directly calculated with the Fourier coefficients of a prescribed path.