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Nowadays automobiles are getting smart and there is a growing need for the physical behavior to become part of its software. This behavior can be described in a compact form by differential equations obtained from modeling and simulation tools. In the offline simulation domain the Functional Mockup Interface (FMI) [3], a popular standard today supported by many tools, allows to integrate a model with solver (Co-Simulation FMU) into another simulation environment. These models cannot be directly integrated into embedded automotive software due to special restrictions with respect to hard real-time constraints and MISRA compliance. Another architectural restriction is organizing software components according to the AUTOSAR standard which is typically not supported by the physical modeling tools. On the other hand AUTOSAR generating tools do not have the required advanced symbolic and numerical features to process differential equations.

This paper presents the Vehicle Dynamics Control (VDC) for commercial vehicles developed by BOSCH. The underlying physical concept is discussed in the second section after a short introduction. The third section shows the computer simulation used in the development process. Section four describes the controller structure of the VDC system. In Section five the use and effectiveness of VDC for commercial vehicles is shown in different critical driving situations. This is done by using measured data collected during testing (lane change, circular track) and it demonstrates that the safety improvements achieved for passenger cars are also possible for commercial vehicles.

VDC is a new active safety system for road vehicles which controls the dynamic vehicle motion in emergency situations. From the steering angle, the accelerator pedal position and the brake pressure the desired motion is derived while the actual vehicle motion is derived from the yaw rate and the lateral acceleration. The system regulates the engine torque and the wheel brake pressures using traction control components to minimize the difference between the actual and the desired motion. Included is also a safety concept which supervises the proper operation of the components and the software.

Since its introduction in March 1995, the market demand for Vehicle Dynamic Control systems (VDC) has increased rapidly. Some car manufacturers have already announced their plans to introduce VDC on all their models. Particularly for compact and subcompact cars the system price needs to be reduced without sacrificing safety and performance. Originally designed for optimal performance with economically feasible components (sensors, hydraulics and microcontrollers) and using a unified control approach for all vehicle operating situations the system has been extended to include various drive concepts and has continuously been improved regarding performance, safety and cost. This paper describes the progress made in the development of the Bosch VDC system with regard to the design of the hydraulic system, the sensors, the electronic control unit, the control algorithm and safety.

The Bosch ABS for passenger cars which has been in production since 1978 has been described in numerous publications. Following the gathering of extensive experience with the Bosch ABS and its installation in the different models of passenger car, the concept has been revised with various upgrade levels in order to further optimize braking performance on µ-split road surfaces with different right/left adhesion coefficients, in order further to improve the operation of the system when braking on very slippery road surfaces and also to adapt the control algorithm to four-wheel-drive vehicles with differential locks.

Alongside steering, accelerating and braking are the basic operations in the automobile which are nowadays still left to the driver to perform in their entirety. In performing these basic functions, it may come about that excessive demands are made upon a driver, these arising due to poor road conditions - rain, snow and ice - or as a result of suddenly changing traffic situations. With the introduction of anti-lock braking systems (ABS), a decisive step has been taken to increase active driving and traffic safety. The ABS prevents the lockup of the wheels during overbraking. The vehicle remains steerable and retains stable directional control. Furthermore, in many cases, a shorter braking distance is gained compared to braking with the wheels locked up. BOSCH has been manufacturing and supplying ABS for passenger cars since 1978 and for commercial vehicles and buses since 1981. ABS has proved to be an overwhelming success in practical usage.

Traction control (ASR) is the logical ongoing development of the antilock braking system (ABS). Due to the high costs involved though, the widespread practice of reducing the engine power by electronic throttle control (or electronic enginepower control) has up to now prevented ASR from becoming as widely proliferated as ABS. A promising method has now been developed in which fuel-injection suppression at individual cylinders is used as a low-price actuator for a budget-priced ASR. First of all, an overview of the possibilities for influencing wheel-torque by means of intervention at the engine and/or brake as a means of reducing driven wheel slip is presented. Then, the system, the control strategy, and the demands on the electronic engine-management system with sequential fuel injection are discussed. The system's possibilities and its limitations are indicated, and fears of damaging effects on the catalytic converter are eliminated.

Software-in-the-Loop (SiL) test environments are the ideal virtual platforms for enabling continuous-development, -integration, -testing -delivery or -deployment commonly referred as Continuous-X (CX) of the complex functionalities in the current automotive industry. This trend especially is contributed by several factors such as the industry wide standardization of the model exchange formats, interfaces as well as architecture definitions. The approach of frontloading software testing with SiL test environments is predominantly advocated as well as already adopted by various Automotive OEMs, thereby the demand for innovating applicable methods is increasing. However, prominent usage of the existing monolithic architecture for interaction of various elements in the SiL environment, without regarding the separation between functional and non-functional test scope, is reducing the usability and thus limiting significantly the cost saving potential of CX with SiL.

The manufacturers of passenger cars increasingly assign development and production of complete subsystems to the supplying industry. A brake system supplier has to give predictions about system quality and performance long time before the first prototypical system is built or even before the supplier gets the order for system development. Nowadays, the usage of computer-aided system design and simulation is essential for that task. This article presents a tool designed to support the development process. A special focus will be on how to define quality. A formal definition of quality is provided, illustrated and motivated by two examples.

During the acquisition phase brake system supplier have to make predictions on a system's thermal behavior based on very few reliable parameters. Increasing system knowledge requires the usage of different calculation models along with the progress of the project. Adaptive modeling is used in order to integrate test results from first prototypes or benchmark vehicles. Since changes in the brake force distribution have a great impact on the simulation results fading conditions of the linings have to be integrated as well. The principle of co-simulation is used in order to use the actual brake force distribution of the system.

This paper presents the conceptual model and the fundamental mechanisms for software development in the context of the Brite-EuRam project Safety Related Fault Tolerant Systems in Vehicles (nick-named X-By-Wire). The objective of the X-By-Wire project is to achieve a framework for the introduction of safety related fault tolerant electronic systems without mechanical backup in vehicles. To achieve the required level of fault-tolerance, an X-By-Wire system must be designed as a distributed system comprising a number of fault-tolerant units connected by a reliable real-time communication system. For the communication system, the time-triggered TTP/C real-time communication protocol was selected. TTP/C provides fault-tolerance message transfer, state synchronization, reliable detection of node failures, a global time base, and a distributed membership service. Redundancy is used for masking failures of individual processor nodes and hardware peripherals.

Actual research results in the automotive field show that there is a big potential in increasing active and passive safety by implementing intelligent driver assisting systems. Realizing such safety related system functions requires an electronic system without mechanical or hydraulic backup to de-couple the human interface from the vehicle functions, e.g., steering and braking. Safety critical functions without mechanical backup enforce new requirements in system design. Any faulty behavior of a component within the system must not lead to a malfunction of the overall system. Consequently in the system design fault-tolerance mechanisms in real time must be introduced. Active replication of a functional node is a proper solution to guarantee this real time fault-tolerance. Redundancy management of the functional nodes can be implemented by fail-silent replicas, i.e. a node behaves correctly or does not produce any output at all.

Since the brake colloquium in 2004 the role of climatic conditions and their relations to noise occurrence, sound pressure level and friction coefficient level is widely discussed in the US and European working groups on brake noise. A systematic study has been started to investigate the influence of relative humidity, absolute humidity and temperature on brake noise and the corresponding friction coefficient level. In this study an enormous effort was taken to keep the influences of the brake parameters, e.g. lining material, Eigenfrequencies and dimensions of the different components as small as possible to investigate the climatic influence only. Strategic humidity and temperature levels were tested according to the Mollier-Entropy-Enthalpy-Diagram which are corresponding to the seasons in the various international regions. A regression analysis evaluates the correlation and the influence of each parameter to noise and friction coefficient level.

The hydrogen engine is one of the promising technologies that enables carbon-neutral mobility, especially in heavy-duty on- or off-road applications. In this paper, a methodological procedure for the design of the combustion system of a hydrogen-fueled, direct injection spark ignited commercial vehicle engine is described. In a preliminary step, the ability of the commercial 3D computational fluid dynamics (CFD) code AVL FIRE classic to reproduce the characteristics of the gas jet, introduced into a quiescent environment by a dedicated H2 injector, is established. This is based on two parts: Temporal and numerical discretization sensitivity analyses ensure that the spatial and temporal resolution of the simulations is adequate, and comparisons to a comprehensive set of experiments demonstrate the accuracy of the simulations. The measurements used for this purpose rely on the well-known schlieren technique and use helium as a safe substitute for H2.

Surround sensing methods provide information which can be used in PRECRASH functionalities for advanced control of the passenger protection system. The relevant data (closing velocity (cv), time to impact (tti), and offset of contact point (Δy)) are determined with a Predictive Safety System and transmitted to the airbag control unit for further processing in the PRECRASH algorithm. The PRECRASH algorithm controls both, the activation of reversible restraints and the deployment of irreversible restraints. Therefore it consists of two components: The PREFIRE and the PRESET algorithm. The PREFIRE algorithm uses the PRECRASH information for the activation of the reversible belt pretensioner in advance of a crash to reduce chest load in the crash phase. The PRESET algorithm calculates the trigger decision for deployment of pyrotechnical restraints. Inputs of the PRESET algorithm are the PRECRASH information as well as the acceleration signal.

ABS has proven to be a contribution to active safety. The introduction of traction control (TC) in 1986 and even more significantly, the introduction of vehicle dynamics control (VDC) in 1995 have been further milestones in this field. The functionality of these systems (ABS, TC, VDC) is mainly determined by the electronic control unit (ECU). A system supplier who is to provide an ECU-platform concept including a large functionality, while meeting customer specific requirements at an optimized price, needs standardization strategies. This paper describes a standardization concept for an ABS ECU, beginning with the basic ABS HW and SW design and the extension to TC and VDC. It also shows the degree of flexibility, the benefits for the vehicle manufacturer and the possible cost optimization for the system supplier.

The article describes the methods, which are employed in order to ensure high performance, safety and quality of ABS and ASR. System behaviour is evaluated and optimized by computer simulation. Moreover, a real-time simulator has been developed by which the consequences of hardware defects can be investigated systematically, Despite the increasing use of simulation the testing of vehicles remains the most important tool for system evaluation. For that purpose, a digital data acquisition system has been developed and objective evaluation criteria have been established. In order to achieve high product quality the Failure Mode and Effect Analysis (FMEA) is carried out at an early phase of development. Another prerequisite for high product quality is thorough durability and endurance testing before release of production.

A new automotive active safely system, the Vehicle Dynamics Control System (VDC) of BOSCH was introduced on the market in 1995. Besides improving the ABS/ASR functions, VDC will also actively support the driver in critical situations of lateral vehicle dynamics. This system includes new ABS/ASR-control algorithms and a superimposed control algorithm, the vehicle dynamics controller. Furthermore, an extension of the standard ABS/ASR-hydraulic system was necessary as well as the development of new automotive sensors. During all phases of the interdisciplinary system development, tests on experimental cars and extensive computer simulations were used in parallel. In order to provide adequate simulation models for different tasks, a modular concept for the simulation tool is important. Furthermore, a transparent and portable application of the control algorithm for both, experiment and simulation, is required.

Electromagnetic Compatibility (EMC) requirements and the effort to fulfill them are increasing steadily in automotive applications. This paper demonstrates the usage of virtual prototyping to efficiently investigate the EMC behavior of a gasoline direct injection system. While the system worked functionally as designed, tests indicated that current and especially future client-specific EMC limits could not be met. The goal of this investigation was to identify and eliminate the cause of EMC emissions using a virtual software prototype including the controller ASIC, boost converter, pi filter, injection valves and wire harness. Applying virtual prototyping techniques it was possible to capture the motor control system in a simulation model which reproduced EMC measurements in the frequency ranges of interest.

In spite of improvements in passive safety and efforts to alter driver behavior, the absolute number of highway fatalities in 2002 increased to the highest level since 1990 in the US. ESP is an active safety technology that assists the driver to keep the vehicle on the intended path and thereby helps to prevent accidents. ESP is especially effective in keeping the vehicle on the road and mitigating rollover accidents which account for over 1/3 of all fatalities in single vehicle accidents. In 1995 Bosch was the first supplier to introduce electronic stability control (ESC) for the Mercedes-Benz S-Class sedan. Since then, Bosch has produced more than 10 million systems worldwide which are marketed as ESP - Electronic Stability Program. In this report Bosch will present ESP contributions to active safety and the required adaptations to support four wheel driven vehicles and to mitigate rollover situations.