Research On Obstacle Avoidance Optimal Motion Planning Of 6-DOF Manipulator

The manipulator is the key component of industrial production and is widely used in manufacturing fields such as handling,spraying,welding,and grinding.With the continuous improvement of precision and performance,the manipulator is gradually being used in electrical and electronic,aerospace,medical,and service fields.As the working environment of manipulators is developing progressively towards openness and complexity,the research on motion planning of manipulators has also received more and more attention from scholars at home and abroad.Aiming at the problems that the motion planning efficiency of the current manipulator is low,the degree of intelligence is weak,and cannot meet the needs of practical applications,this thesis takes the six-degree-of-freedom(6-DOF)manipulator xArm6 of UFACTORY company as the research object,and conducts the following four kinds of research:Firstly,in order to realize the motion planning of the manipulator,the kinematics modeling of the manipulator is required.In this thesis,the kinematic model of the manipulator xArm6 is established by using the modified D-H(MD-H)parameter method,and the corresponding forward kinematic equations are solved and verified.In addition,because the workspace of the manipulator can limit the motion planning space and reduce the failure rate of motion planning,this thesis borrows and integrates the existing method of solving the workspace by using the envelope and named it the group envelope method.The workspace of the manipulator xArm6 is solved.The analytical expressions of the reachable workspace,the dexterous workspace,and the auxiliary workspace are obtained and 3D visualization is carried out.The concept of dexterity is introduced to analyze the workspace.Secondly,from the perspective of reducing the running time of the manipulator,the trajectory planning method of the manipulator is researched.Firstly,the commonly used trajectory planning methods in Joint Space are introduced,including polynomial interpolation,linear trajectory with parabolic blends,and S-curve interpolation.Then,the trajectory planning of space line and space arc in Cartesian Space is derived theoretically,and the simulation of space line and space arc trajectory planning based on cubic and quintic polynomial interpolation is completed.Finally,for the sake of reducing the running time of the manipulator and improving the working efficiency,this thesis makes use of the optimization ability of the genetic algorithm and the local property of the B-spline curve and proposes a time-optimal trajectory planning method based on cubic B-spline and improved adaptive genetic algorithm IAGA optimization.The application scenario of manipulator grasping is simulated in the MATLAB simulation environment,and the simulation comparison is carried out by using the manipulator xArm6 with the traditional genetic algorithm SGA and the adaptive genetic algorithm AGA.It is verified that the method has a stronger ability to optimize the time of the manipulator trajectory.Then,in order to solve the problem of difficulty in generating obstacle avoidance paths in high-dimensional space,the path planning algorithm based on the Rapidly-exploring Random Tree is deeply studied.Firstly,the RRT algorithm and RRT*algorithm are introduced.Then,the RRT*algorithm is optimized from three aspects:constrained sampling space,heuristic guidance,and bidirectional strategy.The dynamic guided RRT*(DG-RRT*)algorithm is proposed with reference to the artificial potential field method.The existing RRT*-Connect algorithm is improved and the RRT*-MC algorithm is proposed.It is verified by simulation comparison that the two proposed algorithms have a certain efficiency improvement.Finally,the proposed DG-RRT*algorithm,RRT*-MC algorithm and Informed RRT*algorithm are combined,and the excellent characteristics of each algorithm are comprehensively extracted,and the Informed Dynamically Guided RRT*Modified Connect Algorithm is proposed,abbreviated as IDG-RRT*-MC algorithm,in as many as 10 kinds of 2D simulation environments and 4 kinds of 3D simulation environments and the cutting-edge two-way RRT*algorithm has been fully simulated experiments compared.The consequence reveals that the algorithm can plan the initial path and the optimal path in a shorter time and with fewer iterations,which verifies the efficiency of the IDG-RRT*-MC algorithm.Finally,for the sake of testing the effect of the proposed IDG-RRT*-MC path planning algorithm on the motion planning of the manipulator,the motion planning experiment of the manipulator is carried out.This thesis takes the manipulator xArm6 as the research object and uses the robot operating system ROS to build the 6-DOF manipulator xArm6 obstacle avoidance optimal motion planning experimental platform.The IDG-RRT*-MC algorithm and the RRT*algorithm are compared in the four obstacle scenarios.The experimental results verify the feasibility and efficiency of the IDG-RRT*-MC algorithm in manipulator motion planning.