Networked Wheeled Mobile Robot Trajectory Tracking Control With Delays

With the rapid development of artificial intelligence technologies,the wheeled mobile robots have found their applications in many areas,such as the scientific expedition,removal of dangerous,relief,combat,security,intelligent transportation and other fields.The trajectory tracking problem has been the focus in the area of mobile robot,it involves kinematics,intelligent control,information processing and other comprehensive issues.Either in the trajectory tracking control of leader-follower mobile robots or remote trajectory tracking control of mobile robot,the introduction of communication networks has broken the limitations of the traditional control system in the spatial position and increased the flexibility of the control system.However,the network-induced delay is often inevitable,which will deteriorate system performance,and even destabilize the trajectory tracking control systems.Therefore,it is of great theoretical and engineering significance to investigate the time delay problem in trajectory tracking system of mobile robot.This thesis investigates the constant distance tracking control problem for the networked leader-follower mobile robots with network induced-delays.The main contributions of the thesis are as follows:1.The leader-follower trajectory tracking control problem is investigated for wheeled mobile robots,and a PID controller is developed based on direct feedback linearization(DFL).A kinematic model is first established for a single wheeled mobile robot by motion analysis.Then a kinematic model is presented for the leader-follower trajectory tracking control system.Furthermore,consider the influence of uncertainties such as wheel slip and the external disturbance factors in practical motion,and a nonlinear coupling system model with disturbance is established.Then,the direct feedback linearization method is applied to obtain the linearization model,and a PID controller which ensures the stability of the system is designed.2.The uncertainties of the mobile trajectory tracking control system caused by the network induced delay are modeled as the disturbances of the system,and an extended state observer(ESO)is designed to estimate the disturbances online.Furthermore,the uncertainties induced by the delays and other model uncertainties are compensated by the ESO using dynamic linearization compensation.In this way,the effects of the network induced delays are removed and the linear active disturbance rejection control(LADRC)method is thus implemented to achieve the objective of high performance trajectory tracking control.3.The remote trajectory tracking control of the mobile robot is investigated,and the network-induced delay problem which is inevitable in the remote control system is considered.The Kalman filter is used to estimate the delays of the wireless network,and the performance of the estimation algorithm is measured in the process of tracking control.Moreover,the Kalman filter based delay compensation method is compared with some existing estimation algorithms.Through accurate delay estimation,remote controller can predict the position of the mobile robot accurately and send real-time control commands to achieve effective remote trajectory tracking of mobile robot.4.Computer simulations and experiments based on the developed mobile robot platform are carried out to demonstrate the effectiveness of the proposed methods.