Research On Vehicular Platoon Control With Non-ideal Communication Condition

Vehicular platoon driving can improve road utilization rate,alleviate road congestion and reduce wind resistance by increasing vehicle density.In recent years,the introduction of wireless communication brings problems of communication delay and communication topology uncertainty to vehicular platoon system.In terms of delay problem,an idea of state prediction to send out prediction state of next sampling period is proposed to compensate for the influence of communication delay.Using eigenvalue decomposition of information topology and linear transformation of the platoon system and the characteristics of similar construction and block diagonal structure,the system dimension is greatly reduced and a decoupled system is obtained,so that the proposed control method can apply to different communication topologies.Based on general Lyapunov function,the proposed controller can be easily solved by means of linear matrix inequalities(LMIs).The effectiveness of the control strategy to maintain the vehicular platoon system stable and robust is validated in communication delay situation.In the first place,the problems of communication delay and system coupling caused by wireless communication are analyzed and the negative influence of communication delay is diagrammatically demonstrated in this paper.The idea of predicting vehicular states of next sampling period is proposed to solve the adverse effect of communication delay.By using the technique of feedback linearization,the nonlinear longitudinal vehicle dynamic model is linearized and the three-order state space equation is obtained.The state predictor is designed based on discrete state space equations and directed graph theory is adopted to describe the information flow interconnecting autonomous vehicles.As for the coupling system,decoupling process is presented by using eigenvalue decomposition of information topology,linear transformation of the platoon system and the characteristics of similar construction and block diagonal structure.The analysis of the system and solution procedure of controller are greatly simplified.Furthermore,based on the decoupling model,inequality constraints to stabilize the vehicular platoon system are obtained by constructing general Lyapunov function,so that the problem of controller solving is transformed into the solving linear matrix inequalities.For the convenience of solving,the number of inequalities is reduced to only four by using the monotonicity of the solving equations.As a result,only the minimum and maximum eigenvalues of communication matrix are necessary.Moreover,the influence of information delay on performance is studied theoretically and it is found that the tolerable maximum delay is determined by the maximum topological eigenvalue.The effectiveness of the proposed strategy is validated by simulating in MATLAB/Simulink.Simulation results show that the decoupled control method is applicable to various information topologies and solve the problem of communication delay.Moreover,the comparative study between the proposed method and another control method irrespective of communication delay is made,which further explains the necessity of considering communication delay when studying the controlling method of vehicular platoon is also explained.