Research On Motion Planning For Mobile Manipulator In Obstacle Environment

With the development of robotics,robots are more and more widely used in fields such as product-manufacturing,housekeeping service,and intelligent warehousing.Meanwhile,there exists a growing demand of the capability of the robots.Therefore,several top countries in the world have formulated policies to increase investment in robot research.Owing to the manipulability and mobility,the mobile manipulator has a wider operation space and a wider application prospect than the conventional base fixed manipulator.At present,the research on mobile manipulator mainly concentrates on the motion planning.Because of the structure complexity and system redundancy,the research on the motion planning of mobile manipulator becomes a great challenge.In view of the motion planning problems of the mobile manipulator,the structure of the mobile manipulator is analyzed in this thesis.On the basis of the analysis of the structure,the kinematic analysis of the mobile robot and manipulator is carried out and the kinematics equation of the mobile manipulator is obtained.Based on ROS,the simulation platform of the mobile manipulator is established.Meanwhile,we can accomplish the motion planning,such as the autonomous navigation of mobile robot,manipulator motion planning and the unified planning of mobile manipulators based on task allocation.The main contents of this thesis are as follows:(1)Based on the structural characteristics of the mobile manipulators,the configuration analysis of the two subsystem of mobile manipulator----mobile robot and manipulator----is carried out.The kinematics equation of mobile robot is established.Forward kinematics model of the manipulator is created by D-H method.The closed solution of the inverse kinematics of the manipulator is solved.Finally,the kinematics equation of the mobile manipulator and the solving strategies of the inverse kinematics are obtained.(2)Based on ROS,simulation model of mobile manipulator is built.By using the RViz,the visualization of the mobile manipulator model is verified.The move_base package and the Move It! configuration package are designed to implement motion control of mobile robot and manipulator.Combining with the individual control of mobile robot subsystem,an overall motion control scheme for the mobile manipulator is proposed.(3)The autonomous navigation of the mobile robot and the motion planning of the manipulator based on the Rapidly-exploring Random Tree(RRT)algorithm is investigated.A task-oriented coordination strategy is proposed.And then the mobile manipulator can achieve the obstacle avoidance planning in an environment with obstacles.(4)Based on ROS,the motion of the mobile manipulator is planned in an environment with obstacles and the simulation verification about the results is performed.The ROS driver of the mobile manipulator hardware is established.And then the experiment is conducted to prove that the results of the motion planning is effective.