Research On Motion Control Of Wheeled Mobile Manipulator For Smart Factory

The wheeled mobile manipulator is composed of wheeled mobile platform and manipulator.Because of its flexibility in space,it can work in large workspace and rich application scenarios,and has strong adaptability to the environment.Introducing the wheeled mobile manipulator into the smart factory and controlling it to perform processing operations in accordance with the reference trajectory can not only replace the traditional fixed manipulator,but also improve the processing efficiency and innovate the processing mode.In order to solve the problems of complex structure and multivariable structure of wheeled mobile manipulator,this paper divides the processing operation process of wheeled mobile manipulator and establishes corresponding mathematical models and control methods to ensure that the wheeled mobile manipulator can successfully complete the task in the scene of smart factory.First,in order to achieve the high-precision trajectory tracking control of the wheeled mobile manipulator in the smart factory scene,the overall kinematics and dynamics model of the wheeled mobile manipulator is established by combining the mechanical structure characteristics of the wheeled mobile manipulator with the rationality assumption,which provides the model reference foe the subsequent design of motion control methods.Secondly,in order to ensure that the wheeled mobile manipulator can reach the target station smoothly in the smart factory scene full of obstacles,the artificial potential field is established for the obstacles in the scene,and the compound control method of mobile platform trajectory tracking and obstacle avoidance based on Artificial Potential Function(APF)is proposed.At the kinematics level,the APF controller can switch between the trajectory tracking control and obstacle avoidance control of the mobile platform,improve the flexibility of wheeled mobile manipulator.Thirdly,aiming at the nonlinear,multivariable and multi constraint problems in the overall trajectory tracking control after the wheeled mobile manipulator arrives at the station,a trajectory tracking control method based on Model Predictive Control(MPC)is proposed.The MPC position and attitude controller is designed to realize the position and attitude error tracking of the wheeled mobile manipulator based on the tracking error model,which can output the required speed in real time.At the same time,the trajectory tracking control of the wheeled mobile manipulator is realized,which lays the foundation for the follow-up research.Finally,an Extended State Observer(ESO)is introduced to solve the problem of unmeasurable state quantities in the trajectory tracking control of wheeled mobile manipulators.On the basis of the above research,a cooperative control method is proposed,which uses an expanded observer to observe unknown speed information,uses an MPC pose controller to track the reference trajectory at the kinematics level,designs dynamics controller based on Sliding Mode Control(SMC).Through the control of torque,the coordinated control of the wheeled mobile manipulator in kinematics and dynamics is realized.This paper studies the modeling and control method of the wheeled mobile manipulator in the smart factory scene,which can significantly improve the adaptability and anti-interference ability of the wheeled mobile manipulator to the complex environment,and realize the stable control of the wheeled mobile manipulator in the intelligent factory scene.The research results of this paper can provide reference for the motion control research of wheeled mobile manipulator.