Vehicle Lane Change Maneuver in Automated Highway Systems

The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the State of California. This report does not constitute a standard, specification, or regulation. Abstract This report is concerned with lane change maneuver in automated highway systems. In this problem, a vehicle, initially under closed loop lane following control on an automated lane, must be guided to the adjacent automated lane. The desired trajectory between two automated lanes is designed by considering the transition time from one lane to another lane and passenger's ride comfort. Four types of the desired trajectories are considered. The nominal steering input that can make the vehicle follow the desired trajectory in the absence of model uncertainties and disturbances is obtained by inverting a linear dynamic model, which relates the steering input to the vehicle lateral displacement. Simulations show that the nominal input alone cannot assure an acceptable level of maneuvering accuracy in the presence of uncertainties and disturbances such as wind gusts and changes in the tire cornering stiffness. The use of onboard sensors for the closed loop control can significantly improve performance. Three closed loop controllers, based on (i) linear quadratic (LQ) optimal control, (ii) frequency shaped linear quadratic (FSLQ), and (iii) sliding mode control will be evaluated for this application. Simulation results show that these controllers provide acceptable performance in the presence of uncertainties and disturbances.Executive Summary In this report, lane change maneuver for an automated highway system is investigated as a tracking problem with respect to the virtual desired trajectory (VDT). The two main issues discussed in the report are: 1) design of virtual desired trajectory and 2) design of control algorithms. The VDT is a desired trajectory for lane change maneuver. The word "virtual" implies that controllers for lane change maneuver do not have physical access to the desired trajectory. Therefore, lane change maneuver is performed in an open loop manner with aid from onboard sensors to reduce sensitivity to the uncertainties. The VDT's are designed to give good ride quality by placing constraints on lateral acceleration and jerk. Another important consideration while designing VDT's is minimization of the transition time. Four types of the VDT are studied in this report: 1) the circular trajectory, 2) the cosine approximation to the circular trajectory, …