Research On Obstacle Avoidance Path Planning For 6-DOF Manipultor

With the continuous improvement of science and technology and the guidance of "China intelligent manufacturing 2025" policy,robot technology has developed rapidly and well in the fields of industrial production,medical treatment,military activities and family services.As one kind of robot,the series manipulator which like man's arm has the advantages of flexible motion,strong versatility,strong obstacle avoidance and easy control,so it is widely applied in industrial production.The obstacle avoidance path planning of robot arm is one of the key technologies in manipulator research field,and its effect will have an important influence on the control effect of robot arm.Therefore,the research of obstacle avoidance path planning technology has important theoretical significance and practical value for robotic arm motion control.This thesis takes six DOF Manipulator as the research object,and it is mainly on the manipulator kinematics,obstacle avoidance and path planning algorithm.Firstly,the kinematics model of the six DOF Manipulator is established by using D_H method.Based on the kinematics model of the manipulator,the forward kinematics is derived,and a method for solving closed kinematics of inverse kinematics is presented.The solutions of the analysis is verified by Matlab software.Secondly,this thesis analyzes the problem of collision detection between the manipulator and the static obstacles in the environment in path planning process.And it mainly introduces three methods of cylindrical envelop method,AABB bounding box and sphere.The model is simplified according to the structure characteristics of the manipulator.The result of the collision detection problem is solved by computing the space location between the arm model and obstacle model.Thirdly,an improved RRT algorithm is proposed for the six degree of freedom manipulator.The advantages and disadvantages of path planning for robot in arm joint space and Cartesian space are analyzed.Because the standard RRT algorithm is highly randomness and low search efficiency,so the target guidance algorithm is introduced to improve the efficiency of path planning.Considering the distance measurement of the joint space,Manhattan metric function is more consistent with the practical significance of the motion of the manipulator.At the same time,in order to solve the problem that the path is not smooth,the B spline smoothing function is introduced to meet the actual motion requirements of the manipulator.SimMechanics virtual prototype is used to simulate the improved algorithm,and the effectiveness and superiority of the algorithm is verified.Finally,the hardware and software of the six degree of freedom manipulator control system are designed.The test platform is established with Beckhoff controller and tsino driver;the control program of the mechanical arm is completed with TwinCAT3 and Matlab/Simulink software.It is proved by tests that the improved RRT algorithm can plan an obstacle free path from the starting point to the target point for the manipulator.