Impacts of communication delay on vehicle platoon string stability and its compensation strategy: A review

Based on the four-element model, this paper reviewed the important research progress in vehicle platoon, compared the advantages and disadvantages of different models in each element longitudinally, and summarized the linkage between each element horizontally. The stability criteria are briefly reviewed from three dimensions: local stability, string stability, and traffic flow stability. The impact of communication delay on vehicle platoon is quantitatively summarized from two aspects: the variation of controller gains and the variation of headway time values. Aiming at the inevitable communication delay in vehicle platoon, the compensation strategies are analyzed from five levels. (1) Optimizing the communication network structure. (2) Reconstructing acceleration information. (3) Tuning controller gains. (4) Constructing a multi-branch selection structure. (5) Improving the controller. The results show that, although these compensation strategies can alleviate the negative impact of communication delay to a certain extent, they also have some defects such as difficulty in adapting to complex and various real road conditions, poor accuracy and real-time performance, insufficient security, and limited application scenarios. It is necessary to further improve the accuracy and real-time performance of the device, design an encrypted and scalable network architecture to ensure communication security and adaptability, and conduct further real vehicle testing.