Dynamic Analysis And Control Design Of A Novel Translational Parallel Robot

In terms of the advantages of simple structure,easily control design and lower manufacturing cost,translational parallel robots with three degrees of freedom have been become one of the research hot focuses in the limited-DOF parallel robots.Many scholars in the robot field have paid more and more attentions on 3-DOF parallel robots due to their well kinematic performances and widely potential applications.A novel 3-DOF fully-isotropic translational parallel robot is presented in this dissertation.It consists of a moving platform connected to a fixed base by three identical kinematical limbs.Every limb is composed of one prismatic pair,two revolute joints and a parallelogram structure which includes two revolute joints and two spherical joints.Kinematics problems of the parallel robot are performed by homogeneous coordinate transformation.The analytic equations about position,velocity and acceleration are established,respectively.The one-to-one corresponding mapping relationship between the inputs of the actuated joints and outputs of the platform is explored.Then the numerical simulation and the virtual prototype simulation are investigated by use of MATLAB and Pro/E software,respectively.The position,velocity and the acceleration curves are described as well.Two kinds of simulation results show that the theoretical analysis is correctness and effectiveness.The dynamic problems of the robot are also discussed.The friction forces/torques equations of the actuated prismatic pairs and the spherical joints are derived based on the “Coulomb + Viscous” friction model.Then,the robot is decomposed three parts,i.e.,the actuated pairs,the kinematical chains and the moving platform.The force models of each part are set up by using Newton-Euler method,respectively.The mapping relationships between the driving forces of the actuated pairs and the external forces applied on the platform are explored.The joint constraint reactions forces and the friction forces/torques of the actuated prismatic pairs and the spherical joints are studied,too.Finally,the dynamic simulation of the robot is performed by use of ADAMS and MATLAB software.The driving force curves of the actuated joints,the friction forces/torques curves of the actuated prismatic pairs and the spherical joints are described by use of software.According to the open control system of “computer+GT400 motion controller”,the control system of the physical robot is presented based on the position control mode,which have four parts,such as a GT400 motion controller,Delta's AC servo system,computer and the physical prototype.The reset and motion programs of the control system are written by Visual C software after the motion controller is initialized,respectively.Through the path tracking function of SolidWorks software,the input function curves and the position coordinates of the end-effector trajectory are solved.The position coordinates obtained are embedded into the motion control program,and the trajectory of the end-effector is depicted.The testing results verify the correctness and effectiveness of the control system designed.The works in this dissertation provide a solid theoretical foundation for the robot application in future.