Adaptive Formation Control For Nonlinear Multi-agent Systems With Unknown Disturbances

Since the beginning of this century,with the continuous vigorous development and integration of science and technology such as computer technology,control science,digital signal processing,and artificial intelligence,multi-agent formation control has been a very active field.Due to its extensive practical applications in biology,physics,social sciences,and sensor networks,and the huge development potential of satellite formation,surveying and mapping,robot monitoring,etc.,there is growing interest in formation control of a group of mobile agents to perform complex tasks.This paper focuses on the adaptive formation control of nonlinear multi-agent systems with unknown disturbances based on relative distance or bearing measurement information.For a class of nonlinear systems with unknown disturbances,the formation control strategy is designed by using the negative gradient method and adaptive algorithm.The global stability of the formation control system based on relative distance and bearing measurement information is analyzed by introducing topological graph theory,angle rigidity theorem,Barbalat's lemma and non-smooth analysis theory.The main research work of this paper is as follows:Firstly,an adaptive triangular formation control with uncertain nonlinear dynamics and external disturbances is studied in this paper.The potential energy function method is introduced to design the adaptive formation control law,nonlinear dynamics are approximated by the first type fuzzy systems.Furthermore,the parameter adaptive estimation is used to eliminate the effects of approximation error and external disturbances.Finally,the Barbalat's Lemma and nonsmooth-theory are used to demonstrate the global stability of the overall fuzzy formation system,and all agents' velocities converge to a common value without collision between any agents.Secondly,this paper considers the nonlinear adaptive formation control problem with unknown bounded disturbances of nonholonomic systems,when distance or position information is difficult to obtain or cannot be accurately measured.Many physical objects cannot be described by a linear model due to the various existing limitations actually,so we propose a new adaptive perturbation formation control law based on bearing-only measurement for the nonholonomic unicycles.The effects of unknown disturbances are eliminated by use of the parameter adaptive estimation method,then the nonlinear theory and non-smooth theory are introduced to prove the global stability of the close-loop systems.Thirdly,in this paper,an adaptive formation control with uncertain nonlinear dynamics and external disturbances is studied,where the control of each robot merely relies on the relative bearings between the communicating robots.The potential function method is introduced to design the bearing-only formation control law,and nonlinear dynamics are approximated by the first type fuzzy systems.Furthermore,the parameter adaptive estimation is used to eliminate the effects of approximation error and external disturbances.Finally,the Barbalat's Lemma is used to demonstrate the global stability of the overall fuzzy formation system.The proposed formation control strategy can ensure that the communication agents can reach the desired relative bearing,thus converging to the desired formation.Finnally,the effectiveness of the adaptive formation control algorithm based on the potential field method is verified by simulations for the nonlinear multi-agent formation system based on relative distance and bearing measurement information.