Structural Design And Analysis Of New Parallel Robot Based On Linkage Mechanism

Delta and its generative mechanism are considered as the most popular and successful parallel mechanism in the industrialized application. Due to its advantages of fast response and high precision, it is widely used in the food, medicine and other industries. From the structure side, the limb of Delta mechanism is a closed-loop parallelogram mechanism, but the research and efficient design theory about the structure of limbs with closed-loop linkage units were few. Some local structure design is unreasonable, which leads to a great obstruction in the process of industrial application. Based on backgrounds above, the configurations of parallel mechanism with closed-loop linkage unit limbs were proposed in this paper, and the analysis and evaluation of kinematics performance of typical mechanism were accomplished, which provide a useful theoretical and technical support for the parallel mechanism's design and application in industrialization.Firstly, in this paper, several different movement forms of limbs were designed based on the reciprocal relationship of constraint screw and kinematic screw, and according to the constraints to moving platform provided by limbs, the mechanisms with different degrees of freedom were presented. Parts of the new mechanism's three-dimensional modeling were proposed, and the specific structure of each mechanism was introduced respectively. Based on the characteristics of linkage and the design principles of more diversity to move, simpler to structure and easier to manufacturing, a novel 3-5RS parallel mechanism was selected as the subsequent study mechanism.Then, the kinematics of the 3-5RS mechanism was analyzed, its main contents include:closed-vector-circle method was used to analyze and solve the forward and inverse kinematic model of the mechanism; speed and acceleration solution of the mechanism kinematics are deduced. And the input and output equations of displacement, velocity and acceleration were built, which lays theoretical foundation for the subsequent research.Next, the performances of the 3-5RS parallel mechanism were analyzed. Workspace of the mechanism was obtained by Mathematica, by using the velocity Jacobian matrix, the mathematical criterion for the singularities of the mechanism is obtained to ensure the safe and reliable motion. Each dimension parameter was optimized by genetic algorithm based on the different performance indexes.Last, based on the above theory and calculation results, the virtual prototype modeling of the 3-5RS parallel mechanism was built and the corresponding kinematic simulation was studied by ADAMS, including the simulation of translational motion and single degree of freedom rotation. Trajectory planning and simulation of the pick-placed task were accomplished, the result further verifies the motion ability of the mechanism and meets the design requirements.