Research On Trajectory Planning And Grabbing Strategy Of DELTA Parallel Manipulators

With the rapid development of economy,more and more enterprises begin to use automatic equipment instead of human beings to work on the production line.DELTA parallel robot is widely used in food,medicine and other industries because of its high speed,high precision,large structure and load capacity.The trajectory planning and grasping strategy of DELTA parallel robot is the core of production line.Therefore,this thesis takes DELTA parallel robot as the research object,aiming at the problem of different density of target objects placed on the conveyor belt,gives a multi-target dynamic grasping strategy based on position prediction,and builds an experimental platform to verify the feasibility of trajectory planning and grasping strategy.Firstly,the mechanical structure of DELTA parallel robot is simplified,and the kinematics of the robot is analyzed according to the simplified structure.The inverse kinematics equations and the forward kinematics equations are given by establishing the robot coordinate system and the geometric relationship of the simplified structure of DELTA parallel manipulator.Then the velocity relation between the joint of DELTA parallel robot and the moving platform is analyzed,and the velocity Jacobian matrix is given,and the possible singular configuration is analyzed according to the velocity Jacobian matrix.According to the forward kinematics calculation process of DELTA parallel robot,the reachable workspace is modeled and simulated with Matlab,and the point cloud map of the reachable workspace is given.Then the multi-target dynamic grasping problem is decomposed into four problems:single-target static grasping,multi-target static grasping,single-target dynamic grasping and multi-target dynamic grasping.Using the modified gate path as the trajectory model,the gripping trajectory of the end-moving platform of the DELTA parallel robot is planned by introducing a five-stage S-shaped acceleration and deceleration algorithm.For dynamic target grabbing,a multi-target dynamic grabbing strategy based on target position prediction is developed.According to the different distribution of the target object on the conveyor belt,the position prediction function based on the distribution of the dense target object and the loose target object is given.Finally,based on the existing conditions of the laboratory,the trajectory planning and grasping strategy of multi-objective dynamic grasping are further validated.The results show that the trajectory planning and grasping strategy of multi-objective dynamic grasping can complete the grasping work well,and the feasibility of the method is verified.