State-Constrained Lane Change Trajectory Planning for Emergency Steering on Slippery Roads

In this paper, a state-constrained optimal solution based real-time vehicle path planning strategy, which aids the vehicle to avoid collision by the lane change maneuver, is presented. More specifically, depending on the driving conditions, the path is generated by considering the elapsed time and the driver's ride quality. Especially, the path is planned based on the trajectory optimization theory (i.e., Pontryagin maximum principle), resulting in the analytical optimal solutions. Furthermore, to handle the state-constrained optimization problem that is considered to ensure the vehicle lateral stability, we include the punctual and isolated equality constraints in the formulated optimization problem, which can designate the state variables as the desired value at the intermediate time instants. Through the numerical examples on various driving conditions and high-fidelity model-based verification, we demonstrate the effectiveness of the developed path planner, and our approach can effectively generate a safe vehicle path rapidly, depending on the road surfaces and vehicle speeds.