The success in the adoption of autonomous vehicles is dependent on their ability to solve rarely occurring safety-critical corner cases. Vehicular communications (V2X) aim at improving safety and efficiency of autonomous driving by adding the capability of explicit inter-vehicular information exchange. We argue that V2X enables another important function, namely the support of ethical driving decisions. In this article, we explain our envisioned methodology of an ethical cooperative driving interaction protocol design (including what to communicate and how to act based on the received information). Cooperative manoeuvring empowered by the ethical V2X is a new research direction we promote in the autonomous driving research agenda. © 2024 IEEE.

Advances in technologies for vehicular communication enable new applications for Cooperative Intelligent Transportation Systems (C-ITS). Communicating vehicles share information and cooperate, which allows for improved safety, fuel economy, and traffic efficiency. Platooning – a coordinated string of vehicles with small Inter-Vehicle Distances (IVDs) – comprises one such C-ITS application. Any C-ITS application must comply with high safety requirements to pass standardization and be commercially deployed. Moreover, trusted solutions should be guaranteed even for critical scenarios or rare edge cases. This thesis presents two sets of contributions related to cooperative automated driving. Firstly, it provides conditions ensuring safe platooning or vehicle following. Secondly, it introduces an ethical framework to guide autonomous decision-making in scenarios involving imminent collisions. In the first set of contributions, we consider emergency braking scenarios for vehicles driving in a platoon or following each other. In such scenarios, the lead vehicle suddenly brakes. This requires swift responses from followers to prevent rear-end collisions. Here, Vehicle-to-Everything (V2X) communication has the potential to significantly reduce reaction times by allowing the lead vehicle to notify followers of the emergency braking. The presented safety analysis yields computationally efficient methods and algorithms for calculating minimum IVDs for rear-end collision avoidance. The IVDs are computed for closed-loop and open-loop configurations. The open-loop configuration implies followers drive with a constant velocity until the onset of braking, whereas in the closed-loop configuration, a controller is used under some restrictions. In addition, a centralized approach for optimization of IVDs in platoon formations is carried out. Such an approach allows for improved fuel consumption and road utilization. An analytical comparison shows that our proposed Vehicle-to-Vehicle (V2V) communication-based solution is superior to classic automated systems, such as automatic emergency braking system, which utilizes only onboard sensors. Wireless communication provides intentions to vehicles almost immediately, which allows for smaller IVDs while guaranteeing the same level of safety.

In the second set of contributions, an ethical framework to guide autonomous decision-making is presented. Even though collisions resulting from edge cases are unlikely, it is essential to address them in motion planning logic for autonomous vehicles. Decisions made in such situations should always prioritize ethical considerations, such as saving human lives. Adhering to ethical principles in the development and deployment of autonomous vehicles is essential for fostering public understanding and acceptance. The thesis presents a framework of ethical V2X communication, where V2X is acknowledged as an essential means for enabling autonomous vehicles to perform coordinated actions to meet certain ethical criteria. The presented framework demonstrates how the risk or harm resulting from unavoidable collisions can be mitigated or redistributed under ethical considerations through cooperation between vehicles. Overall, the presented thesis highlights the importance of C-ITS and, specifically, V2X communication in managing emergency scenarios. V2X communication enables faster response times and facilitates cooperative maneuvers, which helps preventing rear-end collisions or mitigating their consequences under ethical considerations. Future work directions include an extension of the obtained results by considering more advanced models of vehicles, environment, and communication settings; and applying the proposed frameworks to more complicated traffic scenarios.

Formal models for the safety validation of autonomous vehicles have become increasingly important. To this end, we present a safety framework for longitudinal automated driving. This framework enables the calculation of minimum safe inter-vehicular distances for arbitrary ego vehicle control policies in a computationally efficient manner. We use this framework to enhance and generalize the Responsibility-Sensitive Safety (RSS) [1] model and models based on it, which fail to cover situations where the ego vehicle has a higher decelerating capacity than its preceding vehicle. © 2024 IEEE.

Connected and automated vehicles (CAVs) will be a key component of future cooperative intelligent transportation systems (C-ITS). Since the adoption of C-ITS is not foreseen to happen instantly, not all of its elements are going to be connected at the early deployment stages. We consider a scenario where vehicles approaching a traffic light are connected to each other, but the traffic light itself is not cooperative. Information about indented trajectories such as decisions on how and when to accelerate, decelerate and stop, is communicated among the vehicles involved. We provide an optimization-based procedure for efficient and safe passing of traffic lights (or other temporary road blockage) using vehicle-to-vehicle communication (V2V). We locally optimize objectives that promote efficiency such as less deceleration and larger minimum velocity, while maintaining safety in terms of no collisions. The procedure is computationally efficient as it mainly involves a gradient decent algorithm for one single parameter. © 2023 by the authors.

We argue that an information exchange between vehicles via the vehicular communications is the foundation for ethical driving. In other words - autonomous vehicles must be cooperative to be able to resolve ethical dilemmas in a multi-vehicle scenario. We show this by exploring the minimal setting of a longitudinal driving in a formation of three vehicles. © 2023 IEEE.

We conducted a survey to evaluate a previously proposed mechanism for explaining Belief-Desire-Intention (BDI) agents using folk psychological concepts (belief, desires, and valuings). We also consider the relationship between trust in the specific autonomous system, and general trust in technology. We find that explanations that include valuings are particularly likely to be preferred by the study participants. We also found evidence that single-factor explanations, as used in some previous work, are too short. © 2023 International Foundation for Autonomous Agents and Multiagent Systems (www.ifaamas.org). All rights reserved.

Explainability of autonomous systems is important to supporting the development of appropriate levels of trust in the system, as well as supporting system predictability. Previous work has proposed an explanation mechanism for Belief-Desire-Intention (BDI) agents that uses folk psychological concepts, specifically beliefs, desires, and valuings. In this paper we evaluate this mechanism by conducting a survey. We consider a number of explanations, and assess to what extent they are considered believable, acceptable, and comprehensible, and which explanations are preferred. We also consider the relationship between trust in the specific autonomous system, and general trust in technology. We find that explanations that include valuings are particularly likely to be preferred by the study participants, whereas those explanations that include links are least likely to be preferred. We also found evidence that single-factor explanations, as used in some previous work, are too short. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

This paper provides a safety analysis for emergency braking scenarios involving consecutive vehicles which utilize adaptive cruise control (ACC) with a constant-distance policy together with vehicle-to-vehicle (V2V) communication. We identify analytically, how the minimum safe inter-vehicle distance(IVD) that allows avoiding rear-end collision can be shortened with the use of electronic emergency brake lights and derive the explicit dependency of such IVDs on V2V communication time delay. We further show how these results can be used to compute probabilities of safe braking in the presence of packet losses.

A platoon comprises a string of consecutive highly automated vehicles traveling together. Platooning allows for increased road utilization and reduced fuel consumption due to short inter-vehicular distances. Safety in terms of guaranteeing no rear-end collisions is of utmost importance for platooning systems to be deployed in practice. We compare how safely emergency braking can be handled by emerging V2V communications on the one hand and by radar-based measurements of existing AEBS on the other. We show that even under conservative assumptions on the V2V communications, such an approach significantly outperforms AEBS with an ideal radar sensor in terms of allowed inter-vehicle distances and response times. Furthermore, we design two emergency braking strategies for platooning based on V2V communications. The first braking strategy assumes centralized coordination by the leading vehicle and exploits necessary optimal conditions of a constrained optimization problem, whereas the second -- the more conservative solution -- assumes only local information and is distributed in nature. Both strategies are also compared with the AEBS.

New cooperative intelligent transportation system (C-ITS) applications become enabled thanks to advances in communication technologies between vehicles(V2V) and with the infrastructure (V2I). Communicating vehicles share information with each other and cooperate, which results in improved safety, fuel economy, and traffic efficiency. An example of a C-ITS application is platooning, which comprises a string of vehicles that travel together with short inter-vehicle distances (IVDs).

Any solution related to C-ITS must comply with high safety requirements in order to pass standardization and be commercially deployed. Furthermore, trusted safety levels should be assured even for critical scenarios.

This thesis studies the conditions that guarantee safety in emergency braking scenarios for heterogeneous platooning, or string-like, formations of vehicles. In such scenarios, the vehicle at the head of the string emergency brakes and all following vehicles have to automatically react in time to avoid rear-end collisions. The reaction time can be significantly decreased with vehicle-to-vehicle (V2V) communication usage since the leader can explicitly inform other platooning members about the critical braking.

The safety analysis conducted in the thesis yields computationally efficient methods and algorithms for calculating minimum inter-vehicle distances that allow avoiding rear-end collisions with a predefined high guarantee. These IVDs are theoretically obtained for an open-loop and a closed-loop configurations. The former implies that follower drives with a constant velocity until braking starts, whereas in the latter, an adaptive cruise control (ACC) with a constant-distance policy serves as a controller. In addition, further optimization of inter-vehicle distances in the platoon is carried out under an assumption of centralized control. Such an approach allows achieving better fuel consumption and road utilization.

The performed analytical comparison suggests that our proposed V2V communication based solution is superior to classical automated systems, such as automatic emergency braking system (AEBS), which utilizes only onboard sensors and no communication. Wireless communication, enabling to know the intentions of other vehicles almost immediately, allows for smaller IVDs whilst guaranteeing the same level of safety.

Overall, the presented thesis highlights the importance of C-ITS and, specifically, V2V in the prevention of rear-end collisions in emergency scenarios. Future work directions include an extension of the obtained results by considering more advanced models of vehicles, environment, and communication settings; and applying the proposed algorithms of safety guaranteeing to other controllers, such as ACC with a constant time headway policy.