Motion Planning Of Spatial Series Manipulator For Obstacle Avoidance

Space multi-joint serial robot manipulator has been widely used in industrial production,agricultural harvesting,aerospace and other fields due to its flexible movement and strong versatility.In the application of manipulator,path and trajectory planning is the key technology of its motion control,and is also one of the important hotspots in the field of robot research.Two important problems need to be solved in motion planning: first,when the dimension of workspace changes from two-dimensional plane to three-dimensional space,the scale of path search space increases;second,if there are obstacles in the working environment,efficient obstacle avoidance motion planning is needed.In this paper,the multi-degree-of-freedom tandem manipulator is taken as the research object.In the two-dimensional and three-dimensional obstacle workspace,obstacle avoidance path planning and joint space trajectory planning algorithms are studied.Firstly,based on the kinematics of the serial manipulator,a 3-DOF plane and a 3-DOF3-D space robot mathematical model are constructed respectively,and it is modeled in MATLAB Robotics Toolbox.Based on Monte Carlo point cloud method and computer graphics,two-dimensional and three-dimensional mathematical geometric models of obstacle avoidance workspace are obtained,which lay a foundation for subsequent motion planning.Secondly,in obstacle avoidance workspace,two kinds of planning algorithms are proposed according to the shape of obstacles and the working requirements of robots.They are geometric path planning algorithm for simple obstacles and short-distance operations,and the improved Dijkstra algorithm for complex obstacles and long-distance operations.The corresponding collision-free planning path is obtained.In the environment of MATLAB,the principles of the two algorithms and the corresponding paths are analyzed and simulated in detail in terms of search efficiency and practicability.Finally,after obtaining the motion path of the robot end effector,according to the mapping relationship between Cartesian space and robot joint space,the motion trajectory of each joint of the manipulator is obtained.Several path points are selected on the search path of the obstacle avoidance workspace,and the joint angles of each joint are calculated by inverse kinematics solution.In order to make the trajectory continuous and smooth,the cubic and quintic polynomial interpolation functions are used to plan and simulate the trajectory of the planar and three-dimensional manipulators respectively.The angular velocity and acceleration curves of each joint under different paths are obtained and compared.Through the analysis of manipulator motion modeling and simulation results,the proposed planning method is feasible,and has certain theoretical significance and practical application reference value for robot motion control.