Research On Fixed-time Formation Control For Multiple Mobile Robots

With the continuous development of modern technology and the popularization of computer technology,the multi-mobile robot system has been rapidly developed and researched.The multi-robot formation system has become a research hotspot at home and abroad due to its powerful functions,stable performance and good robustness.Compared with the traditional progressive time formation control,the fixed-time formation control converges faster,and the upper bound of the convergence time does not depend on the initial state.So the research on fixed-time formation control has very important practical significance.This paper first studies the fixed-time formation control problem of the follower robot in the slipping state.Then considers the limited energy and network bandwidth of the multi-robot system,an event trigger mechanism is introduced,the formation control problem of multi-mobile robots at fixed time is studied based on event triggering.The main research contents of this paper are as follows:Aiming at the slip condition of the follower robot in the multi-mobile robot system,this paper designs a fixed-time formation control method.Based on the study of the sliding motion law of mobile robots,a distance-angle based model of distance-angle formation is established,and a fixed-time formation controller is designed based on the fixed-time stability theory using state feedback technology.A radial basis function neural network(RBFNN)was used to compensate the uncertain information generated by the follower robot's slip,and a fixed-time formation controller embedded in RBFNN is designed according to the fixed-time theory and Lyapunov stability theory.The designed formation control algorithm can ensure that the follower robot converges to the desired formation within a fixed time,and the convergence time has nothing to do with the initial state,only related to the parameters of the controller design.Finally,the formation control algorithm is simulated by Matlab,and the simulation results verify the designed controller is reasonable and effective.At the same time,considering the slow convergence speed and limited energy of mobile robots,this paper designs a fixed-time formation control method based on event triggering.A trigger function is constructed based on the fixed-time theory and Lyapunov stability.The designed controller can make the multi-robot formation system quickly converge to a stable state within a fixed time,and the upper bound of the convergence time does not depend on the initial conditions.Compared with the traditional progressive time formation control,the formation control method designed in this paper can not only reduce the communication frequency,but also speed up the convergence speed of the system,while eliminating the Zeno behavior.Finally,the effectiveness of the formation control algorithm is verified by Matlab numerical simulation.The multi-robot experiment platform is built to further verify the effectiveness of the designed RBFNN fixed-time formation control algorithm.The mobile robot used is Turtle Bot3,and the position,orientation,speed and other data information of multiple robots are collected through high-frequency projection positioning technology.The information is sent to the upper computer for processing through the radio frequency communication system,and the processed information is sent to each robot through the relay board and the photoelectric receiving board.Finally,according to the formation control algorithm designed in this paper,the verification of the multi-robot formation control algorithm is completed on the experimental platform.