Forschungsgesellschaft Kraftfahrwesen Aachen (Germany)

Development and safety validation of highly automated vehicles increasingly relies on data and data-driven methods. In processing sensor datasets for environment perception, it is common to use public and commercial datasets for training and evaluating machine learning based systems. For system-level evaluation and safety validation of an automated driving system, real-world trajectory datasets are of great value for several tasks in the process, i.a. for testing in simulation, scenario extraction or training of road user agent models. Ground-based recording methods such as sensor-equipped vehicles or infrastructure sensors are sometimes limited, for instance, due to their field of view. Camera-equipped drones, however, offer the ability to record road users without vehicle-to-vehicle occlusion and without influencing traffic. The highway drone dataset (highD) has shown that the recording method is efficient in terms of cumulative kilometers and has become a benchmark dataset for many research questions. It contains many vehicle interactions due to dense traffic, but lacks merging scenarios, which are challenging for highly automated vehicles. Therefore, we propose this highway drone dataset called exiD, recorded using camera-equipped drones at entries and exits on the German Autobahn. The dataset contains 69 172 road users classified as car, truck and vans and a total amount of more than 16 hours of measurement data. For non-commercial public research, the exiD dataset is available free of charge at https://www.exid-dataset.com.

Objective: In order to introduce automated vehicles on public roads, it is necessary to ensure that these vehicles are safe to operate in traffic. One challenge is to prove that all physically possible variations of situations can be handled safely within the operational design domain of the vehicle. A promising approach to handling the set of possible situations is to identify a manageable number of logical scenarios, which provide an abstraction for object properties and behavior within the situations. These can then be transferred into concrete scenarios defining all parameters necessary to reproduce the situation in different test environments.Methods: This article proposes a framework for defining safety-relevant scenarios based on the potential collision between the subject vehicle and a challenging object, which forces the subject vehicle to depart from its planned course of action to avoid a collision. This allows defining only safety-relevant scenarios, which can directly be related to accident classification. The first criterion for defining a scenario is the area of the subject vehicle with which the object would collide. As a second criterion, 8 different positions around the subject vehicle are considered. To account for other relevant objects in the scenario, factors that influence the challenge for the subject vehicle can be added to the scenario. These are grouped as action constraints, dynamic occlusions, and causal chains.Results: By applying the proposed systematics, a catalog of base scenarios for a vehicle traveling on controlled-access highways has been generated, which can directly be linked to parameters in accident classification. The catalog serves as a basis for scenario classification within the PEGASUS project.Conclusions: Defining a limited number of safety-relevant scenarios helps to realize a systematic safety assurance process for automated vehicles. Scenarios are defined based on the point of the potential collision of a challenging object with the subject vehicle and its initial position. This approach allows defining scenarios for different environments and different driving states of the subject vehicle using the same mechanisms. A next step is the generation of logical scenarios for other driving states of the subject vehicle and for other traffic environments.

This contribution proposes a model-based predictive control approach for combined longitudinal and lateral vehicle guidance. The controller, which has been designed for an automotive collision avoidance system, aims at following a desired evasion trajectory at the handling limits. Thereby, the trajectory following problem is decomposed in a path following and a velocity trajectory tracking problem using the wheel steering angle and the longitudinal acceleration as control inputs. There are two major advantages of this approach. First, the a priori knowledge of the evasion trajectory is explicitly incorporated into the computation of control inputs. Second, the combined transmission of longitudinal and lateral tire forces is considered in the sense of an integrated vehicle dynamics control approach. Experimental results show the potential of the introduced control scheme.

Scenario-based validation is a promising approach for the safety validation of highly automated driving systems. By modeling relevant driving scenarios, utilizing simulations and selecting insightful test cases, the testing effort is reduced. However, current methods can't automatically create intuitive models of the vehicle trajectories in a scenario. We propose to use unsupervised machine learning to train neural networks to solve the modeling problem. The models learn a small set of intuitive parameters without the need for labeled data and use them to generate new realistic trajectories. The neural networks, which base on the InfoGAN and beta-VAE architectures, are adapted from the image domain to the time series domain. Although our methods are generally applicable, our experiments focus on lane change maneuvers on highways. To train the networks, we use more than 5600 measured lane change trajectories extracted from the highD dataset. Our results show that the networks learn to describe lane change maneuvers by up to four intuitive parameters. Furthermore, the networks are able to map existing lane change trajectories to values of the learned parameters and generate new, previously unseen, realistic trajectories. We compare both architectures among themselves and to a polynomial model, and show respective advantages.

Automated driving functions are under intensified development by industry and academia since the last decade. Due to the large operation space and various complex scenarios automated driving functions have to cope with, assessment efforts are expected to rise dramatically. In order to quantify benefits and risks of these functions in an efficient way, this paper describes a holistic approach for the assessment of automated driving by using real world driving data. Based on a scenario definition a suitable method for identifying relevant scenarios from real world driving data is described which is able to handle scenario specific characteristics such as the temporal and spatial dependencies of all traffic participants. For quantifying the effect of automated driving within the considered driving scenarios, the statistical indicator `effect size' is applied. The basic requirement that automated driving needs to operate within mixed traffic implies that the reference for assessment needs to be human manual driving behaviour.

<div class="htmlview paragraph">In this paper the relationship between weight reduction and fuel economy is determined. This is executed with simulations for the three different propulsion systems ICE (internal combustion engine), hybrid system and fuel cell (FC) system. Furthermore, the three different vehicles classes compact, mid-size and SUV are considered along with two driving cycles, NEDC and HYZEM. The re-sizing of the propulsion systems according to the lighter vehicle weight to achieve the same acceleration as the basis vehicle is implemented as well.</div> <div class="htmlview paragraph">As an overall result it is established that no general value for the fuel consumption reduction per weight reduction exists. It is very important to consider all boundary conditions, especially the used driving cycle, the examined vehicle class, the type of propulsion system and a possible powertrain re-sizing. In detail the results show values between 2 and 8 % fuel consumption reduction at a 10 % weight reduction. Conventional powertrains fall in a range of 2 to 6 % fuel consumption reduction for all driving cycles and vehicle classes. A strong impact of the powertrain re-sizing on the fuel consumption reduction is detected for the conventional powertrains, especially in the NEDC driving cycle. For the alternative powertrains the re-sizing has less impact.</div>

Automated vehicles rely heavily on data-driven methods, especially for complex urban environments. Large datasets of real world measurement data in the form of road user trajectories are crucial for several tasks like road user prediction models or scenario-based safety validation. So far, though, this demand is unmet as no public dataset of urban road user trajectories is available in an appropriate size, quality and variety. By contrast, the highway drone dataset (highD) has recently shown that drones are an efficient method for acquiring naturalistic road user trajectories. Compared to driving studies or ground-level infrastructure sensors, one major advantage of using a drone is the possibility to record naturalistic behavior, as road users do not notice measurements taking place. Due to the ideal viewing angle, an entire intersection scenario can be measured with significantly less occlusion than with sensors at ground level. Therefore, we created a comprehensive, large-scale urban intersection dataset with naturalistic road user behavior using camera-equipped drones as successor of the highD dataset. The resulting dataset contains more than 13 500 road users including vehicles, bicyclists and pedestrians at intersections in Germany and is called inD. The dataset consists of 10 hours of measurement data from four intersections and is available online for non-commercial research at: https://www.inD-dataset.com.

Abstract Der Zusammenhang zwischen dem Wärmeübergang und der Bewegung der Feststoffteilchen wird für das Fließbett und das Moving Bed untersucht. Für den Mechanismus des Wärmeüberganges im Fließbett ergibt sich: Die Kontaktzeit der Feststoffteilchen an einer wärmeaustauschenden Fläche bestimmt den Wärmeübergang; er steigt mit abnehmender Kontaktzeit an und strebt gegen einen Optimalwert. Dieser ist durch das Vorhandensein einer Gasschicht zwischen der Austauschfläche und den körnigen Feststoffteilchen bedingt. Entgegen einer oft vertretenen Ansicht ist die Gasgeschwindigkeit ohne direkten Einfluß auf den Wärmeübergang. Weiter wird über Versuche berichtet, bei denen bisher wenig untersuchte Einflußgrößen in Fließbetten, wie z. B. der Gasdruck und die Gasverteilung sowie die Feststoffzirkulation, verändert wurden.

Abstract Fuel cells are a promising propulsion technology option in sustainable and zero‐emission drivetrain strategies as they offer a high potential to significantly reduce well‐to‐wheel greenhouse gas emissions and the dependency on fossil energy resources. At the same time, the current technological performance of automotive fuel cell systems is not yet sufficient to meet market demands. Therefore, the technical development of fuel cells is a critical factor for a successful market introduction of fuel cell electric vehicles (FCEV). This paper describes the methodology and results of a two‐round Delphi Survey conducted by the Institut für Kraftfahrzeuge of RWTH Aachen University to assess the technological potential of polymer electrolyte membrane fuel cell (PEMFC) systems in automotive applications by 2030. The analysis of the current and future performance level of key performance indicators (KPI) of automotive fuel cell systems helps to identify critical performance parameters and to prioritize research and development demands. KPI analyzed in the Delphi Survey as forecast parameters include system efficiency, durability, power density, and specific power.

Scenario-based safety validation is a new approach to handle the increased testing complexity of highly automated vehicles. After categorizing traffic into relevant driving scenarios, every scenario element needs to be modeled in order to be used for testing. While driving maneuvers are typically modeled by experts, data-driven generative models allow to automate the modeling process. We propose an improved unsupervised modeling approach called BézierVAE, which is based on our previously published TraVAE framework. TraVAE is extended by a Bézier-curve output layer, which ensures the trajectories' smoothness in both the position and speed domain. The results are evaluated on lane changes and acceleration/deceleration trajectories extracted from the highD dataset. In comparison to our previous findings, BézierVAE learns a larger set of intuitive model parameters through unsupervised learning, hence enabling a more detailed modeling process. At the same time, the reconstruction errors are reduced by up to 91.3% and the unsmoothness decreased by 83.4% compared to TraVAE. Partially specifying parameters in a semi-supervised fashion maintains the ability to learn disentangled parameters while allowing the parameter learning process to be guided. Finally, we demonstrate the modeling of multiple maneuvers through a single model by introducing discrete parameters into the latent representation.

Despite the steadily declining number of pedestrian fatalities and injuries in most European countries during recent decades, pedestrian protection is still of great importance in the European Union as well as in Germany. This is because they still constitute a large proportion of road user casualties and are more likely to suffer serious and fatal injuries than most other road users. In 1999 only car occupants suffered more fatal injuries than pedestrians in Germany. In December 1998, EEVC WG 17 completed their review and updating of the EEVC WG 10 pedestrian test procedure that made it possible to evaluate the protection afforded to pedestrians by the front of passenger cars in an accident. Within the scope of this procedure, four different impactors are used representing those parts of the body which are injured very often and/or very seriously in vehicle-pedestrian-collisions. In a project executed by IKA and BASt, a small family car was tested according to the EEVC WG 17 test procedure. Afterwards modifications to the car were carried out in order to improve the pedestrian protection provided by the vehicle design. There were certain restrictions placed on the level of modifications undertaken, e.g. only minor modifications to vehicle styling and to the vehicle structures, which provide passenger protection. The redesigned vehicle was tested again using the WG 17 test procedure. The test results of the modified vehicle were compared with those of the standard vehicle and evaluated. The results show that considered measures for pedestrian protection in many areas of the vehicle front structure and the use of innovative techniques can lead to a significant reduction of the loads of pedestrians at an acceptable expense. For the covering abstract see ITRD E111577.

In den letzten drei Jahrzehnten ist der Anteil der Elektronik in Kraftfahrzeugen dramatisch gestiegen. Die Anteile werden immer größer und der Trend hält, getrieben von steigenden Kunden- und Umweltanforderungen ungebremst an. Nahezu alle Funktionen des Fahrzeugs werden heute elektronisch gesteuert, geregelt oder überwacht. Bislang fehlte ein fachlich fundierter und vollständiger Überblick. Diese Lücke schließt nun das Handbuch Kraftfahrzeugelektronik und zeigt einen umfassenden Querschnitt der heute in Fahrzeugen eingesetzten Elektronik.

The implementation of anticipating driving styles in adaptive cruise control systems promises to considerably reduce fuel consumption of vehicles. As drivers have to accept the optimised driving styles of such systems, which implement longitudinally automated driving, the optimisation results should not deviate strongly from the average driving behaviour. This work presents an approach to the optimisation of the vehicle's longitudinal dynamics, which is based on a predicted average driving profile. The proposed approach ensures that the optimisation results meet the expectations of drivers by directly accounting for driver's preferences on weighting up travel time against fuel consumption relative to the average driving profile. Based on human decision finding, rational and intuitive planning decisions are modelled in a cost function and represent optimisation constraints. The approach generally includes information from vehicle‐to‐vehicle and vehicle‐to‐infrastructure communication (V2X), which is an extension to the state‐of‐the‐art. This study describes the optimisation approach and presents a method to determine suitable optimisation parameters in order to consider driver's preferences. The optimisation approach is applied in a simulated test drive and improvements in fuel economy are analysed. Finally, the authors sketch a reference system architecture to prove the feasibility of the presented approach.

Automated valet parking can help manage space in parking garages more efficiently and increase the comfort for the driver by delegating the parking task to the system. To successfully navigate the vehicle in a parking garage, the valet parking system requires a-priori information about the environment. This paper shows an approach to derive a-priori information from available blueprints of a parking lot. Based on the derived map data, paths for Ackermann-steered vehicles are planned to navigate vehicles through the parking area and park them into desired parking spots.

The increasing electrification of the drive train in the automotive environment leads to higher requirements for automotive systems and their design. Therefore, a computer based methodology to support the engineer in the design phase of car concepts, components and control algorithms is desirable. All relevant sections of a vehicle development process, e.g. longitudinal and lateral dynamics, thermal management or the power supply should be considered. Due to this necessity a new holistic vehicle library is developed at the Forschungsgesellschaft Kraftfahrwesen mbH Aachen (fka) and Institute of Automotive Engineering (ika) of

The approach of communication-based intersection assistance is described. Different technology scenarios were analyzed in a realistic traffic simulator to cover a wide time horizon and a wide area of system complexity. The results regarding the specification of the necessary communication technology are proposed. Additionally the different technology scenarios are assessed regarding to the expected user acceptance and their effect on traffic safety. The most important parameter for the reduction of intersection accidents is the equipment rate with communication-based intersection assistant systems. The starting point of the technology concepts is today's available communication technology. -Based on the presented simulation study two technology concepts for communication based intersection assistance are recommended.

This study compares real-traffic deceleration and cut-in scenarios, which were established as critical to automated vehicles (AVs) safety, between Japanese and German highway trajectory datasets. Both scenarios were extracted from two different traffic data previously collected in Japan with both instrumented vehicles and fixed cameras over highways (SAKURA dataset) and in Germany with drones (highD dataset). Five vehicle kinematic variables (lateral and longitudinal distances, velocities, and accelerations) were used to parameterize both scenarios and compared them between datasets using correlation and intersection objective measures and safety metrics: Time-to-Collision and Time Headway. Despite the differences in the rule of the road (e.g. speed limits left- and right-hand traffic), road design, and data sources between the two countries, data comparison results revealed significant correlations and intersections of parameters distribution for both scenarios. The Time-to-Collision significantly overlapped between countries for both scenarios. However, differences in the Time Headway indicate that the safety distance varied across both countries, suggesting that safety assessment methodologies need to be tailored to different environments and regions to ensure safety. These results highlight the potential to develop safety indicators applicable at the international level and warrant further data collection and comparative studies that support the development of harmonized, widely applicable, and region-neutral AVs safety assessment methodologies.

Trotz aller Unterstützung durch elektronische Steuerungs- und Regelsysteme kommen Pkw-Fahrwerke der neuesten Generation nicht ohne die konventionellen Fahrwerkelemente aus. Mit Blick auf die Fahrdynamik werden in diesem Band die konventionellen Elemente und deren Zusammenwirken mit mechatronischen Systemen dargestellt. Dabei werden zunächst Grundlagen und Auslegung, danach in besonders praxisnaher Darstellung die Fahrdynamik dargelegt. Es folgen ausführliche Beschreibungen und Erläuterungen der modernen Komponenten. Ein eigener Abschnitt widmet sich den Achsen und Prozessen für die Achsenentwicklung. Mit einigen überarbeiteten Abbildungen und Aktualisierungen in Text und Literaturverzeichnis konnten gegenüber der ersten Auflage bereits Verbesserungen vorgenommen werden.

SUMMARY In the last five years the IKA (Institut für Kraftfahrwesen Aachen) and BMW created the microscopic traffic simulation program PELOPS. It simulates the traffic flow on motorways with a specific view on vehicle affairs. One application for PELOPS was the assessment of ACC (Adaptive Cruise Control) systems inside the PROMETHEUS program. It was shown, that PELOPS is a powerful tool for the analysis of new technologies. A new research period will extend the use of ACC about the functionality in urban areas. This requires an extension of PELOPS about some specific models. With this extension it is possible, to analyse new traffic technologies for the individual vehicles or the infrastructure. In a first step, PELOPS is extended about functions for suburban areas. This effects mainly the modelling of the driver behaviour. The driver behaviour is related to the traffic situation. In contrast to the normal traffic flow on motorways, the driver has to stop and go in the suburban area, he has to control lower distances and he has to react on other vehicles on cross-roads. New concepts for these functions are included in PELOPS and calibrated by detailed traffic data from a video observation and floating car measurements in the surrounding of Aachen. Based on the traffic measurement near Aachen, different scenarios are simulated to improve the traffic flow and to relieve the environment. These scenarios include ACC systems, inter-vehicle-communication and intelligent traffic lights. The paper shows some information's about the simulation technic and the results from the described analysis.

<div class="section abstract"><div class="htmlview paragraph">Vehicles powered by electric machines offer the advantage to be more silent than vehicles equipped with an internal combustion engine. On the one hand, the reduced noise levels enable an improvement of the inner-city noise pollution. On the other hand, quiet vehicles entail risks not to be acoustically detected by surrounding pedestrians and cyclists in the lower speed range. The emitted noise can easily be masked by the urban background noise. Therefore, the UNECE has founded an informal working group which is currently developing guidelines in terms of an exterior noise required for detecting Quiet Road Transport Vehicles (QRTV). With the introduction of an Acoustic Vehicle Alerting System (AVAS), not only the exterior noise but also the perceived interior noise for an enhanced driving experience can be considered. Nevertheless, car manufactures have a big interest in maintaining their perceived brand identity. For the solution of this task, a synthetic sound generation system has been developed. Besides the realization of executable software for real-time capable vehicle communication and sound calculation, an implementation on an in-vehicle control unit has been engineered. Special attention has been paid to the aspect “ease of use”. Important control parameters of the sound design can be modified with a graphical user interface directly in a road test from both in- and outside the test vehicle. The methodology of the AVAS, different sound design approaches for various demonstrator vehicles and key results regarding the audibility and sound quality are object of this paper.</div></div>