| As an important part of modern logistics system,the path planning and trajectory tracking ability of mobile robot determines the operation efficiency of logistics system.However,in practice,the existing algorithms have some problems such as poor path planning ability and low tracking accuracy.In order to improve the quality of mobile robots walk path and trajectory tracking precision,this paper puts forward the global path planning algorithm based on improved RRT-Connect and local path planning algorithm based on improved DWA,at the same time design based on the speed of the adaptive trajectory tracking controller based on sliding mode variable structure,and through the simulation and experiment prove the effectiveness of the proposed algorithm in this paper.The main research contents and conclusions of this paper are as follows:(1)According to the chassis hardware characteristics of Turtlebot2 mobile robot,the kinematics model of two-wheeled differential mobile robot is established,the coordinate system transformation relationship of mobile robot in the moving state is deduced,and the grid method is selected to carry out the simulation analysis of map construction in the MATLAB environment.(2)Aiming at the problem that the sampling points of the traditional RRT-Connect algorithm are too random,the artificial potential field method and the restricted sampling point extension condition are introduced into the extension function of RRT-Connect algorithm to accelerate the convergence speed of the algorithm.Meanwhile,aiming at the problem of redundant path nodes,a node screening mechanism based on Dijkstra algorithm is proposed to solve the problem of global path broken lines and too many corners.Simulation results show that the maximum path length is shortened by 27.3% and the maximum running time is shortened by 92.88%.In addition,aiming at the problem that the traditional DWA algorithm needs to repeatedly calculate the Angle deviation between the predicted trajectory and the target point,the target distance function is introduced to replace the Angle deviation function and the optimal weight parameter is selected.The simulation results show that the average planning time of the improved DWA algorithm is reduced by 36.18%,and the planning efficiency of the algorithm is effectively improved.(3)For trajectory tracking of traditional sliding mode control problems low tracking precision of the algorithm,is proposed based on adaptive sliding mode variable structure speed trajectory tracking control algorithm,based on the mobile robot three state variable x,y,theta,respectively,the horizontal position controller,vertical position controller is designed and course Angle controller,at the same time,the desired trajectory curvature adaptive speed controller was designed,Simulation results show that the original trajectory tracking control algorithm of the transverse and longitudinal position error need to convergence when t = 6s,and expect the longitudinal position error between the constant greater than zero,and based on adaptive sliding mode variable structure speed trajectory tracking control algorithm can keep at the initial moment smaller horizontal position error and the longitudinal position error,And the lateral and longitudinal errors can converge rapidly,which effectively improves the accuracy of the mobile robot in tracking the desired trajectory. |
