Automotive Systems Engineering

The chapter reflects many years of working on systems development in industry and academia and gives a personal view of the subject. This is not based on systematic research, has no claim to be representative and may be highly subjective. It is the product of experience gained in a number of predevelopment projects and an initial development for volume production at a tier-one supplier, as well as university research into functional and methodological aspects of systems engineering.

This chapter begins by defining some terms, and proceeds to review characteristic elements of Systems Engineering, first in general and then specifically for the automotive sector. An overview of frequently used methods is then followed by a discussion of the specific challenges posed by automotive Systems Engineering for industry and academia. Finally, the resulting recommendations are presented and examples of the scientific work on Automotive Systems Engineering in our Institute of Automotive Engineering (FZD, Fahrzeugtechnik TU Darmstadt) are introduced.

The complexity of modern vehicles requires new methods for vehicle development. Based on two decades of experience in automotive R&D the author motivates to take more benefits from systems engineering. Advantages are expected in three areas: objective evaluation of capabilities, mastering complexity and functional safety. To handle the growing complexity different kinds of system architectures and innovative development processes are introduced. New methods and tools have been developed to test and simulate complex systems in the design phase. Examples are taken from research and development of driver assistance systems and autonomous vehicles.

Vehicle automation features are becoming more and more important in the field of advanced driver assistance systems in order to increase the vehicle’s safety, comfort and economy. However, a possible risk involved with this development is to simply add vehicle automation functionalities to already existing electronic architectures, leading to an overload of human-machine interfaces, intransparent system borders and a constantly increasing overall system complexity. To overcome this driver-assistance dilemma, the research project PRORETA 3 aims to develop an integrated assistance approach by combining a virtual “Safety Corridor” function for accident prevention with the paradigm of cooperative and semi-automated vehicle automation.

This chapter describes in detail the design process of an appropriate system architecture, which is an important factor for efficient system development. Relevant architecture requirements are presented and an overview is given of the state of technology of vehicle automation architectures within the field of advanced driver assistance systems and robotics.

The chapter closes with a proposition for an exemplary behavior-based layered architecture design for a cooperative automation concept, which, as a novel feature, incorporates the human-machine interface as an integrated element of the architecture itself. Due to its modular approach, the proposed design offers the possibility to also incorporate different levels of vehicle automation and allows a flexible span of functional coverage.

Energy efficiency gain is becoming more and more important in present-day and future mobility against the background of increasing energy costs and emission regulations. Ecological Advanced Driver Assistance Systems can contribute to increasing the energy efficiency by providing advanced ecological assistance functions. Focusing on the systematic networking of vehicular functions, especially the power train and driver assistance systems seems to be a promising approach to be able to realize the desired advanced ecological assistance functions. A universal system architecture is proposed as a basis for the development of a wide range of networked ecological assistance functions. The main requirement for the eco\(_2\)DAS system architecture is the universal applicability and scalability to different vehicle and propulsion system types. Based on an energy-consumption influence analysis and basic use-case scenarios for ecological support, a Functional Analysis Architecture is derived. This architecture view describes the overall system functionalities, their structure and the information flows. The system functionalities are summarized in discrete modules and the requirements for these modules are described. The functional overview based on Functional Analysis Architecture and the module requirements are the basis further concretization and implementation of exemplary eco functions.

Despite the advances in automatic driving in the last years, running an automatic vehicle in public traffic is still quite a challenge. One of the main components of an automatic car is the environmental perception system. It processes the measurement data of different sensors and provides the basis for the decision algorithms. As part of the project Stadtpilot at TU Braunschweig, a flexible architecture for environmental perception has been developed. This paper presents the architecture’s static view. It offers an easy to use object oriented framework for creating different sensor data fusion applications for vehicle environmental perception. By defining detailed interfaces between the architecture’s elements down to single classes, algorithms and processing stages can be easily replaced to support the developer.

Conduct-by-Wire (CbW) is an innovative vehicle guidance concept that shifts the vehicle control task from the stabilization level to the guidance level. Instead of continuous stabilization on a designated trajectory—using the conventional control elements for manual steering, braking and accelerating—a CbW vehicle is controlled by means of maneuver commands. This concept allows a maximum degree of automation, while—unlike fully automated concepts—still keeping the driver responsible for the vehicle guidance according to the 1968 Vienna Convention on Road Traffic. In this article a methodology for the technical feasibility assessment of the Conduct-by-Wire principle in the early concept phase is proposed. Starting at the system level with the development of the CbW system architecture the CbW functionality and a cooperative interaction concept—the gate concept—are stepwise concretized. Moreover, the driving situations this cooperative vehicle guidance concept has to cope with are systematically derived. These steps build the basis for analyzing whether the gate concept as a theoretical approach to cooperatively pass the decision points along the planned trajectory during the maneuver execution might also be suitable in practical use. The assessment is focused on analyzing the time available to the driver or the automation for the decision-making process. These studies at the system level build the basis for concretizing the functional development that is exemplarily shown for the determination of the requirements of the environment perception system. Following this systems engineering approach allows for handling the complexity and for a stepwise development. Furthermore, a decision on whether the realization of this innovative concept is worth can be made at different abstraction levels before a prototype system has to be built up.

For the development of Advanced Driver Assistance Systems, the assessment of benefits and potential risks are crucial factors. An example is the controllability assessment of unintended reactions of ADAS as described in ISO 26262. One method this standard proposes for the assessment is the car clinic with naïve subjects. The effort needed to apply this method is analyzed regarding the statistical boundaries. As this effort is considered to be unjustifiable in most cases and in particular if the transferability of results to other systems or situations is low, an approach to increase the transferability is outlined. Therefore, controllability situations due to unintended reactions of ADAS functions are analyzed for contributing and influencing factors, differentiating between the driver and the environment. The goal is to identify a minimum set of necessary test cases with high situational relevance and high influence on controllability. To measure the change in controllability, an assessment criterion for a hazardous situation in longitudinal traffic is developed. The combination of the situational relevance and the controllability assessment allows an overall relevance factor to be derived which weights the situations. This enables the identification of the necessary test cases for assessment of unintended reactions of Advanced Driver Assistance Systems.

The contribution introduces a modular and flexible experimental vehicle for investigation of novel vehicle electronics. The experimental vehicle features 4-wheel-drive, 4-wheel-steering and electric brakes. Each wheel can be actuated individually. All actuators are controlled by-wire without mechanical or hydraulic fall-back layer. To evaluate the safety of the experimental vehicle on the topmost functional layer (“vehicle layer”), a novel approach for targeted safety analysis is introduced. The approach especially aims at by-wire vehicles with a high degree of functional redundancy between different actuation units and strong integration of driving functionalities as steering or braking. For demonstration, the results of a simplified hazard analysis according to ISO 26262 for operation of the experimental vehicle in a well defined environment are presented. The results serve as a basis for safety evaluation of the vehicle using the introduced approach.

The performance of advanced driver assistance systems (ADAS) is strongly dependant on the quality of the used environmental perception sensors and algorithms.

A large number of today’s automobiles, right down to the compact car segment, are equipped with vehicle dynamics control and driver assistance systems. In general, each one of these functions has been developed with its own dedicated set of sensors, and applied independently of other sensors installed in the same vehicle. As a result, redundant measurements are performed, the advantages of which are currently only utilized in a few cases. The increasing powerfulness of microprocessors and the availability of bus systems in vehicles offer a basis for a central processing of the large quantity of data already available. In this article, criteria are shown for selecting and combining methods for data fusion, integrity monitoring and signal quality estimation from a system design and integration point of view, i.e. which integrity and error detection algorithm fits the requirements for working with signals from cost-effective series sensors and offering useful results for the application together with driving dynamics control and driver assistance systems. Also, the ease of series application and usability in existing system architectures will be considered.The structure of a system architecture for centralized, consistent fusion of random pieces of data is shown and evaluated using an example. The sensors used here are acceleration and yaw rate sensors produced using micro-electro-mechanical system (MEMS) technology combined to an inertial measurement unit (IMU) with 3 degrees of freedom, a single-channel (L1) GPS receiver that issues raw data (pseudo ranges and carrier phase measurement), as well as odometry sensors measuring angle pulses from all four wheels and the steering wheel angle. In addition, an evaluation of the signal quality based on usage of redundancies is shown. In general, many different, proven methods for evaluating the integrity of signals or a sensor fusion system exist. Although first definitions of, and requirements for integrity in the automotive sector exist, no appropriate algorithm concept, and no system architecture has yet been defined, and the existing methods only partly fulfill the requirements. Hence, in this article a top-down approach will be shown, beginning at the requirements of automotive integrity, and leading to the definition of an automotive integrity and accuracy benchmark, as well as a system architecture suited for the integration into existing and future system setups. For this purpose, a description of the signal quality by means of integrity and accuracy is shown, and components for such a description are shown by way of example.

Generally, a reconfigurable system is a component-based system that consists of several hardware and software components that are independently developed either on-site, or by third parties (Denaro et al. 2003). As a result, reconfigurable systems involve the ability to replace one or more component(s) of the Device-Under-Test (DUT), which permits new possible configurations that make the test process an expensive burden. Indeed, most of the existing test techniques are foiled by the assumption that the internal structure of the DUT is known with at least partial access to the source code (Bezerra et al. 2001)