On Control Strategy and Safety Verification of Automated Vehicles

Licentiatavhandling, 2013

Over the last few decades, congested traffic network have become a serious problem in many countries. Congestions result in time losses, increase of fuel consumption, increase of CO2 emissions and also raise the risk of accidents. While developing the road networks is not a feasible solution in many countries, intelligent transportation systems (ITS) may contribute to mitigate such problems. It is known that human errors or the delay in human’s reactions is the main cause of many of the problem in current transportation systems. Hence, cooperative driving or in particular vehicle platooning is an example of an ITS which exploits advanced technology like, on-board vehicle sensors, wireless communication and control engineering to improve the traffic situation. However, development of such complex system requires a reliable control algorithm which can guarantee passenger safety and comfort while satisfying certain specifications. This thesis deals with the development of a distributed control strategy for a vehicle platoon. The aim of the control strategy is to enable platooning with a short inter-vehicle distance while fulfilling the so called string stability criterion and maintaining the safety and comfort. The control design is divided into longitudinal and lateral control of vehicle. Simulation and experimental results indicate that string stability in longitudinal and lateral direction can be achieved using the proposed control strategy. Furthermore, a safety verification method based on reachability analysis technique and invariant set theory is proposed for safety analysis of such autonomous systems for a given cooperative controller. The safety verification method is extended to account for model uncertainty and measurement noises. The findings in this thesis are verified through simulations and field tests.