Combined Formation Control Of Heterogeneous Multi-agent Based On Disturbance Observer

With the innovation and upgrading of science and technology,more and more tasks in practical engineering need to be completed with the help of agents.With the rapid development of communication,computer and control technologies,multi-agent system has become a research topic of many scholars and researchers.Self-agent represented by mobile robots,unmanned aerial vehicles(UAV)and unmanned ground vehicle(UGV)have many advantages,such as easy expansibility,economy,flexibility,autonomy and robustness.It has a very broad application prospect in both military and civilian areas,so it has received extensive attention from many scholars.Therefore,based on the above problems,this dissertation will take quadrotor UAV and two-wheeled UGV as the research subject,and constitute a heterogeneous multi-agent system.The formation keeping and trajectory tracking problems in this system are studied.The controllers of formation keeping and trajectory tracking are designed respectively.And the disturbance observer method is introduced to solve the problem of external disturbances.The main research contributions in this dissertation are as follows:Firstly,to solve the formation keeping problem of heterogeneous system of quadrotor UAV and two-wheeled UGV,a relative error system model based on virtual-leader method is established.Combining with the idea of variable structure sliding mode control,a formation keeping controller is designed for UGV,in order to achieve the formation keeping of this system.The effectiveness of the formation keeping controller is verified by simulation.Secondly,to solve the trajectory tracking problem of heterogeneous systems of quadrotor UAV and two-wheeled UGV,a trajectory tracking controller is designed based on the virtual-leader control strategy.According to the under-actuation characteristics of the quadrotor UAV,the system is divided into four subsystems.And the corresponding trajectory tracking controllers are designed respectively.The stability of the system is proved by Lyapunov theory,and the effectiveness of the controller is verified by simulation.Thirdly,to solve the problem of external disturbance in heterogeneous systems,the disturbance observer method is used.A non-linear disturbance observer is developed to observe the mismatched disturbance.And a controller is designed to compensate the disturbance by combining sliding mode control method.The effectiveness of the proposed disturbance observer and controller are proved by Lyapunov theory.The stability of the heterogeneous system has been verified by simulation.