Optimization of emergency trajectories for autonomous vehicles with respect to linear vehicle dynamics

This paper looks at a trajectory planning strategy for autonomous vehicles. The pre-defined nominal trajectory is analyzed with reference to obstacles modeled from circular safety areas. Based on the results of this analysis an emergency trajectory is calculated by using the method of elastic bands. The behavior of the trajectories calculated with this method has been proven to provide flexible trajectories with minimal changes of curvature and therefore good driveability. However in a second step the dynamic behavior of the vehicle is evaluated using the well-known bicycle model along with a first approximation of the steering angle along the trajectory. The trajectory of the vehicle calculated from this steering angle is then improved by iterating the steering angle based on an optimization algorithm

1. Introduction

The increasing traffic density of vehicles demands high attentiveness of each motorist and cyclist. Although additional active safety features as e.g. ABS, ASR or ESP systems have been introduced along with traffic regulations like speed limits or other restrictions, any inattention may still cause well-known problems like automobile accidents and traffic jams. Therefore there is still growing attention to the development of intelligent or automated highway systems circumscribed as Intelligent Transportation Systems (ITS) [1]. They are represented by Autonomously Guided Vehicles (AGV). The primary goal of future AGVs is to ensure the safety of the occupants and the vehicles [2].