Vehicle stability analysis of transport latencies and dropped packets on wireless communication of an off-site steering controller

Abstract

With autonomous vehicles being introduced around the world the possibility of controlling these vehicles from o -site locations presents itself as an opportunity to increase occupant/user safety as well as system e ciency. This applies not only to passenger vehicles but to vehicles in the industrial sector as well. To safely implement o -site control requires an understanding of how vehicle control is a ected by larger transport latencies and dropped packets, which are inherent properties of a wireless network. This study aimed to shed some light on these e ects on lateral control of a passenger vehicle when the vehicle's controller was placed o -site. In this study a Linear Quadratic Self-Tuning Regulator (LQSTR) controller, making use of a vehicle model based on auto-regressive theory describing the relationship between the yaw rate and steer angle of a vehicle, was used. A simulation study showed that the controller was able to control the vehicle through a Double-Lane-Change (DLC) -manoeuvre at vehicle speeds of at least 80 km=h while maintaining very low path tracking errors. With only minor alterations made to the controller's parameters the system was then subjected to transport latencies and packet drops between the vehicle and its controller to simulate o -site vehicle control. It was found that control of the vehicle was lost when latencies between the vehicle obtaining sensor data and a subsequent control action being realised were in excess of 240 ms and packet drop percentages reached 40% to 50%. If no packets were dropped, i.e. 0% packet drop, transport latencies could be as high as 460 ms before control of the vehicle was lost entirely.