Study On Path Planning And Trajectory Tracking Control Alogorithm For Mobile Robot

With the development of science and technology,the nonholonomic wheeled mobile robot(NWMR)have become increasingly popular due to its improved intelligence.The NWMR can be widely used not only to perform some simple commands,but also to complete some complex tasks.Especially,path planning and trajectory tracking are the important basis for NWMR to compete more complex works.However,it is difficult to use general time-invariant control algorithms to control the NWMR,for its movement is restricted by the nonholonomic constraint.Therefore,the path planning and the trajectory tracking control algorithm are deeply studied in this paper.The main research contents are as follows:Firstly,the relationship among robot position,velocities and control force are detailed analyzed.Then the kinematic model and dynamic model of NWMR are established,respectively.Meanwhile,an integrated dynamic model with the consideration of the unmodeled dynamics and external disturbances is further established and its related properties are also briefly introduced.Secondly,regarding to the theory about path planning,the hybrid algorithm combining the improved A* algorithm and the artificial potential field method is presented such that the robot can reach the destination along a designed optimal path with non-fixed environmental information.Simulation results and experimental results show that the proposed algorithm has better planning effect than traditional algorithm.In addition,an observer-based adaptive sliding mode control(ASMC)algorithm is proposed for the trajectory tracking control problem of NWMR systems with external disturbances.A disturbance observer is used to estimate the external disturbances,unmodeled dynamics and others.An adaptive sliding mode controller is designed based on the information obtained by the observer.Simulation results show that the designed method has better effect of tracking than traditional sliding mode control algorithm.Finally,considering the finite-time trajectory tracking problem of NWMR with both unmodeled dynamics and external disturbances,a switched second order sliding mode(S-SOSM)control scheme is proposed to make up for the chattering problem exists in the traditional sliding mode control algorithm.Particularly,state space partitioning is constructed to obtain the bounds of uncertain functions and accomplish different control objectives under different requirements.Simulation results and experimental results show that the proposed controller not only can greatly reduce the tracking error,but also has strong robustness.