Research On Dynamic Analysis And Trajectory Planning Of Wheeled Mobile Manipulator

According to the strategic deployment of "Made in China 2025",robotics is booming as a critical research direction.The mobile manipulator combines the advantages of the fixed manipulator and mobile robot,making up for the shortcomings of the fixed manipulator in the restricted range of motion and low flexibility.And mobile manipulator is more and more commonly used in intelligent manufacturing.The wheeled mobile manipulator system is composed of a movable platform,and a robotic arm fixed on the movable platform.There is a strong coupling between the mobile platform and the robotic arm in the wheeled mobile manipulator,a current research hotspot in robotics.Therefore,it is very important to study the dynamic model and trajectory planning of the wheeled mobile manipulator system.This thesis is based on the 6-DOF AUBO-i5 manipulator and the 3-DOF EAI movable platform to form a 9-DOF wheeled mobile manipulator system.Research the inverse kinematics solution and dynamics modelling methods of wheeled mobile manipulators and carried out trajectory planning based on dynamics.Firstly,to solve the mobile manipulator's operating space.The traditional Monte Carlo algorithm is used to improve the operation space generated by the Gaussian distribution function to make the operation space boundary fuller.Iteratively solves the inverse kinematics founded on the functional area's density function and takes each joint's value iteratively.Each time the matter is made,the objective function is taken to the maximum value within the operating space.This solution method can ensure that the inverse solution value of the robotic arm is optimal every time.Secondly,in view of the strong coupling of the wheeled mobile manipulator's structure composed of a movable platform and a manipulator,it is proposed to use a floating base to solve the dynamics of the mobile manipulator.Convert the mobile manipulator into a combination of a manipulator and a virtual floating floor,introduce a space vector to model its dynamics,solve a multi-body system that combines a manipulator and a floating base,and consider the coupling of the system.After the torque compensation,the coupling relationship between the mobile platform and the robotic arm is obtained,laying the foundation for the following trajectory planning.Thirdly,trajectory planning is based on the mobile manipulator's coupled dynamics model,and the time-optimal trajectory planning problem based on the dynamics model is transformed into a convex optimization problem for solution.Considering the use environment and stable operation of the mobile manipulator,the energy consumption limit and the acceleration change rate limit are added to the objective function.Narrow the timeoptimal trajectory planning algorithm's energy consumption and acceleration change rate to match the job requirements further.Finally,algorithm set out in the present thesis is compared with the overall Jacobian matrix inverse motion algorithm of the mobile manipulator,which shows the algorithm's effectiveness and accuracy.Verify the coupling dynamics model of the established mobile manipulator reflects the accuracy of the dynamic model.Experiments were conducted on the improved time optimal trajectory planning algorithm of the mobile manipulator based on dynamics.Display the superiority of the enhanced trajectory algorithm in this thesis.