Cooperative systems are expected to have a great impact on the road traffic of the future. ITS based on communication between vehicles (V2V) and between vehicles and the infrastructure (V2I and I2V), however, has great potential to contribute to greater energy efficiency and less environmental impact, as well as safety benefits. Many of the cooperative systems presented in different projects have not yet been implemented and the needs for analyses of these systems are big. In my Ph.D. studies, I am identifying cooperative systems with great potential of improving the conditions on the road with respect to efficiency and environmental impacts. The potential benefits of the identified systems are then quantified by means of microscopic traffic simulation. By the use of microscopic traffic simulation individual vehicles in the traffic stream are considered, which allows modelling of different cooperative systems. The benefits with using microscopic traffic simulation is that already at an early stage, before actual development and deployment, evaluations of the cooperative systems can be performed. As a result of the studies cooperative systems with great potential of improving the road conditions can be presented.
Ph D student: Ellen Grumert, email@example.com, Linköpings University and VTI.
Advisors: Professor Jan Lundgren, Dr. Andreas Tapani
The iQFleet project is financed by VINNOVA (FFI) and Scania; other partners are the
Automatic Control Group, KTH and VTI. The aim of iQFleet is to develop the concept of
vehicle platooning in real traffic conditions. While the Automatic Control Group develop
algorithms for controlling the platoons, ToL develop methods for incorporating real-time
traffic conditions in the platoon control, and analyze the performance of the platoon in
surrounding traffic. For the first task, real-time floating car data from trucks are combined
with other traffic and weather data sources to estimate and predict the speed on the highway
between the platoons from origin to destination. For the second task, a model for the
dynamics of truck platoons is developed and implemented in existing traffic simulation
models. The impact of the platooning on the surrounding traffic, and vice versa, is evaluated
under a range of different scenarios, including light/heavy traffic, good/poor visibility,
different number of lanes, different platoon lengths, etc.
Ph D Student: Qichen Deng, Royal Institute of Technology KTH).
Advisor: Professor Haris N. Koutsopoulos, Dr. Erik Jenelius, Dr. Xiaoliang Ma.
Reliable vehicular communications
Vehicular ad-hoc networks (VANETs) are an important part of Intelligent Transportation Systems and aim at increasing road safety, efficiency and driving comfort. These PhD studies are focusing on reliability and security issues of inter-vehicular communications in connection to the ongoing standardization activities in Europe.
The cooperation between vehicles in VANETs is achieved by the frequent exchange of periodic broadcast messages also known as beacons. The beacons might be delivered poorly due to the congested vehicular communication channel or even become a target for different malicious intrusions. This might compromise security, which is crucial for automotive systems.
Beaconing triggering rules, distributed channel congestion control, denial-of-service attacks and misbehavior detectors as well as other related mechanisms to support cooperative awareness between the vehicles in VANETs will be thoroughly investigated.
This study is part of the ”ACDC: Autonomous Cooperative Driving: Communications Issues” project (2014-2016) funded by the Knowledge Foundation in cooperation with Volvo GTT, Volvo Cars, Scania, Kapsch TrafficCom and Qamcom Research & Technology.
Ph D student: Nikita Lyamin, Halmstad University.
Main advisor: Prof. Alexey Vinel, Halmstad University.
Automation and the nature of driving – the effect of adaptive cruise control on drivers’ tactical driving decisions
Advanced driving assistance systems that offer support by operating for example longitudinal control will have an effect on the transport system. Previous studies have also shown that drivers may be slower to respond in hazardous situations with systems like adaptive cruise control (ACC) engaged, if the system suddenly fails. Little understanding has, so far, emerged to explain why. In this thesis, a situated approach to cognition was used to explain how the drivers’ goals and priorities might change with the opportunity of delegating control to a system. Additionally, drivers’ tactical driving decisions were studied to determine how a system such as ACC is integrated into driving. Such changes could, possibly, impact measures like response times as well. The research focused on how drivers handle the addition of ACC to their drive, especially when managing traffic conflicts. Traffic conflicts are not rare events, but form part of everyday driving. Three methods were used: A questionnaire addressing drivers’ understanding of system limitations, a simulator study on handling traffic conflicts when using ACC, and a database study of a field operational test comparing driver responses with and without ACC.
The studies show that drivers do take system behaviour into account when handling traffic conflicts, sometimes allowing the system to act, sometimes by resuming manual control themselves. Previous experience with ACC was also found to affect not only drivers’ knowledge of system limitations, but also their response time to unwanted system behaviour. Drivers were, as previously found, slower to respond with automation than without in simulated driving. In contrast, when studying driver response times in the field test, drivers were faster to respond to a cut-in situation with ACC active than without. The freedom of drivers to use the system as they wish may cause it to be used under different circumstances than in simulator studies, thus explaining the inconsistency with previous results.
The results of this thesis indicate that tactical driving behaviour in common traffic situations is an important factor when discussing the effects of ACC and other advanced driver assistance systems. Thus, the cases in which driving is affected by the system are extended from system failures to a wide range of different situations. Merely using operational measures will miss this aspect, thus risking a depiction of driving with automation as more risky than it is. Rather, driving with automation needs to be studied from a tactical perspective, determining first how the systems are being used. Only then can the relevant operational measures be studied.
Ph D student: Annika Larsson, Lund University.
Advisors: Dr. Katja Kircher, Dr. Åse Svensson, Professor András Várhelyi.
Identification of Safety Critical Events: Development of a new innovative method
When evaluating the safety effects of emerging in-vehicle systems, for natural reasons, crash data cannot be used (they are relatively few and ethically indecent waiting for them to occur). Hence, we need safety indicators occurring more frequently than accidents. It is known that the probability of being involved in safety critical events, including accidents, increases as the as the number of errors in the driving increases, especially tardy decelerations, too short headway to the vehicle in front and poor speed adaption to the traffic situation (Risser 1985). Although these high risk events are more frequent than accidents they are not easy to measure or observe as they occur randomized in place and time, hence there is a need of a new method for identifying safety critical events that can be used in longitudinal studies.
The project is to assess the relationship between self reported accident involvement and the occurrence of safety critical events in the driving and examine if the method would be able to distinguish safety critical events from non safety critical events. These two different kinds of braking events has shown similar levels of acceleration forces in previous studies (van der Horst, 1990; Várhelyi, 1998; Wahlberg, 2000; Malkhamah et al., 2005; McLaughlin et al., 2008) and it has not been possible to distinguish one event from the other.
Safety critical events are measured in terms of jerks, which is a measure of the abruptness in an evasive manoeuvre, i.e. the rate of change in the acceleration of the vehicle, the second derivate of speed. High risk behaviour decreases the safety margins for road users to compensate for their own or other road user’s errors in traffic (Risser 1985) suggesting that driver’s need to act more sudden and with lesser possibility to plan their actions in these situations. It is thus expected to see an increased amount of jerks amongst driver involved in accidents than drivers that have not been involved in accidents.
Dr. Omar Bagdadi defended his thesis ”The development of methods for detection and assessment of safety critical events in car driving” on Oct. 16th, 2012.
Ph D student: Omar Bagdadi, firstname.lastname@example.org., Lund University and VTI.
Advisors: Professor András Várhelyi.
Facing Failures: Interactions between Drivers and Advanced Driver Assistance Systems
Ph D student: Niklas Strand, Chalmers.
Advisor: Professor MariAnne Karlsson.