Trajectory Tracking Control Of Mobile Manipulators

A mobile manipulator system is composed of a mobile platform and a robotic arm that fixed upon it.This system has advantages of mobile platform's large workspace and the dexterity of a robotic arm.At present,it has been widely used in the fields of industrial introduction,ocean exploration,housekeeping,etc.In the process of mobile manipulator tracking control,the mobile platform is subject to nonholonomic constraints,it is also a typical uncertain system with parametric uncertainties in the dynamic model and disturbances from the external environment or unmodeled dynamics,etc.Such factors always affect the tracking performance of mobile manipulator.Thus,it is of great importance to study the trajectory tracking control of mobile manipulator.In this thesis,the trajectory tracking control of mobile manipulator is investigated,and the main works are as follows:1.Combined with nonholonomic wheeled mobile robot dynamic constraint characteristics,the kinematics and dynamics model of mobile manipulators were established,and the system dynamic properties are also illustrated,which provides a reasonable model basis for the trajectory tracking control of mobile manipulator.2.A controller based on extended state observer is proposed for the tracking control of mobile manipulator with external disturbances.This method has the ability to estimate and compensate the external disturbances,and it can eliminate the impact of disturbances on system performance.Simulation results demonstrate that the proposed method can achieve the trajectory tracking of full states in the task space.3.An adaptive sliding mode controller is developed for the position control of mobile manipulator in the presence of dynamic uncertainties and disturbances.An adaptive law is introduced into the sliding mode controller,and it can estimate the system uncertain parameters.The proposed controller can not only guarantee the stability of the system,but also improve the dynamic performances of the system.4.The trajectory tracking control of mobile manipulator is investigated,in which the system dynamics parameters are completely unknown.Firstly,a velocity control law is designed according to the kinematics model of mobile platform.Then,a robust controller based on the Lyapunov theory is designed according to the separate dynamics model of mobile manipulator.Under this scheme,the trajectory tracking control of system velocity and position are achieved5.Conclusions and future works are presented in the end of the thesis.