The automotive powertrain is undergoing a transformation due to the increased electrification. This transformation brings a number of technical challenges relating to the design and integration of electrified elements into the powertrain with it. Powertrain-related targets can be achieved in an increasing number of ways by varying and balancing the powertrain elements. This chapter discusses the challenges that engineers are facing in the development and production of internal combustion engines, e-drives, transmissions, batteries, and fuel cells, and how a systems engineering approach is the key to understand and take advantage of all the possibilities in such complex electrified powertrains.

Electrification adds a new dimension of complexity to powertrain development compared to conventional architectures. Due to its central role within a powertrain, i.e., the distribution of power and adaptation of speed/torque, the transmission is of special interest during the development of hybrid and electric powertrains. A variety of powertrain architectures has emerged due to electrification such as power-split and a range of parallel hybrid configurations. Dedicated hybrid transmission (DHT) architectures can also enable dynamically adjustable powertrain configurations by actuating different friction elements. Systems engineering for transmission development provides a structured approach to find the most appropriate solution for specific powertrain projects that satisfies all stakeholder needs. This case study focuses on the key elements of transmission architecture specification as well as on the continuous tracking of functional targets throughout the project. System simulation receives special attention due to its supportive and even enabling role for both transmission architecture specification and for the verification and validation of transmission functions.

The automotive industry has recently invested considerable efforts into increasing a level of automation as well as an ever-tighter integration with other vehicles, traffic infrastructure and cloud services. Novel Advanced Driver Assistance Systems (ADAS) features and Automated Driving Functions (ADF) drive the need for advances and novel engineering solutions (especially with respect to safety and security). However, they are highly relying on existing components developed in the traditional automotive development landscape. Just as safety-related solutions and mindset became common sense in the development phases in the late 20th century, the automotive domain must now consider novel constraints originating from highly automated and distributed driving functionalities. These cannot be supervised by drivers as an integral part of the development of modern vehicles. Unfortunately, there is still a lack of experience with development approaches for automated driving and safety engineering of such automated functionalities which have no driver in the loop for monitoring. In the current transition phase more and more automated driving functions become integrated in conventional vehicles and thus relay on safety components developed in the light of conventional passenger vehicle usage. This paper concentrates on the constraints and additional considerations to be taken into account when developing or integrating existing safety-related components developed for conventional vehicles in the context of highly automated or autonomous vehicles.

Drivetrain models play an important role in state-of-the-art automotive drivetrain and control concept development. Based on a proposed set of elementary drivetrain components, this article contributes a generic straightforward approach to compute state-space models for various geared drivetrain layouts, including complex hybrid multi-mode transmissions. The modular approach follows Lagrange formalism: The free motion of rigid shafts is subsequently constrained, considering connecting elements like spur and planetary gear sets. The generalized coordinates are determined by a coordinate partitioning method, ensuring a physically reasonable coordinate system. The proposed approach features high potential for automation. This enables drivetrain modeling by non-experts in the field of mechanical engineering.

Kürzere Entwicklungszyklen, hoher Kostendruck und größere Anzahl an Fahrzeugvarianten in der Automobilindustrie verlangen neben anderen Kriterien nach höherer Effizienz in der Fahrzeugentwicklung. Der Einfluss von Elektronik und Software ist maßgebend und nimmt aufgrund steigender Anforderungen und Möglichkeiten durch größere Speicher und schnellere Prozessoren weiter zu. Der Druck nach steigender Effizienz in der Software-Funktionsentwicklung, der Funktions-Parametrisierung und der Absicherung von Fahrzeugvarianten durch Frontloading-Prozesse ist daher groß.

From its early beginnings, the automotive industry has always been known for creating fascinating, innovative new solutions and concepts. Today's vehicles are evolving from computers-on-wheels towards the internet of everything and data-on-wheels. Automotive systems currently exhibit increased levels of automation as well as ever tighter integration with other vehicles, traffic infrastructure, and cloud services. As a result, a shift of the value creation in the automotive domain toward information and communications technology (ICT) domain can be observed over the years. This can be perceived as boon or bane - it greatly increases complexity and uncertainty, but at the same time opens up new opportunities for realizing innovative safety functions. Novel advanced driver assistance systems features or automated driving functions drive the need for advances and novel safety and security solutions, while highly relying on existing components developed in the traditional automotive development landscape. Novel constraints coming from highly automated and distributed driving functionalities which can not be supervised by drivers must therefore be considered as an integral part of the development of modern vehicles. But within these terms a lack of experience with development approaches for automated driving and safety engineering of such automated functionalities still exist. In the current phase, more and more highly automated driving functions become integrated in conventional vehicles relying on safety components developed for conventional passenger vehicle usage. This paper will concentrate on the constraints and additional points to be considered when developing or integrating existing safety-related components developed as SEooC in the context of highly automated vehicles.

In recent days lots of effort is spent on the integration of multi-core processors also in embedded realtime systems domain for several reasons, such as continuously increasing performance requirements and stricter power limitations. This trend is reflected also in the automotive field. Another major aspect for this up-coming trend is the increasing amount of ECUs within the vehicle. Modern vehicles are equipped with 70 to 100 ECUs communicating trough the existing networks within the vehicle with each other to handle the necessary control SW system for vehicle operation. With upcoming multi-core technologies this amount could be reduced by combining different control application with possibly mixed criticality into one multi-core ECU.In this paper, a smart environment for the efficient validation of innovative system architectures based on multi-core platforms in order to be able to handle this future trend in the automotive field is presented. The motivation is to provide a hybrid environment (mixing simulation and physical components) for development of dependable automotive based on multicore controllers and thus reduce validation efforts and costs. The major objectives of the paper addresses the integration of multi-core technology in existing control applications in order to provide more computing resources for (a) improvement of existing functions and (b) development of novel functionalities and the electrical and functional integration of high dynamic controls with time based vehicle control algorithm.

In contrast to conventional and classical hybrid electric transmissions, multimode (hybrid electric) transmissions open new perspectives in gear shifting: The tradeoff between avoidance of propulsion torque interruption and dissipation in clutches can be resolved by smart utilization of the second, coequal, propulsion element, and rearrangement of standard shift phases (torque phase and inertia phase). The resulting smooth and lossless gear shifts reach a new level of performance combining comfort and efficiency. Therefore, modeling and control of these gear shifts is an ongoing automotive research topic since several years. However, so far there is no systematic, model-based approach, which would enable broad application in industry. This paper contributes to bridge this gap. The key point is a systematic determination of a consistent set of generalized coordinates, corresponding to a specific gear, i.e., set of locked clutches. This is achieved by exploiting the mechanical peculiarities of drivetrain topologies. Based on this, a straightforward transformation is proposed to derive a comprehensive state-space model for each gear of a given topology. This enables the statement of the control problem for smooth and lossless gear shifting in a novel compact and general form. Finally, a new shift procedure and a generic-model-based feedforward control is proposed and applied to an exemplary multimode transmission. Promising first simulation results confirm the significance of the proposed approach for further investigation and application.

In this paper, the operation of two clutches during a gear shift process in dual clutch transmissions is considered. An optimization problem is formulated in a compact form such that the energy losses in the clutches as well as the jerk are minimized. Nonlinear constraints arising from clutch friction are avoided by imposing constraints in a linear form and dividing the time interval into two phases. Simulation results of selected load downshift and upshift scenarios illustrate that the current state of the art transmission control approach can be interpreted as an optimal solution.

This article describes a concept for dynamic state estimation of an automotive drivetrain comprising multiple friction elements (like clutches and brakes) within gear transmissions. Adaptive time-step methods for solving model equations are unfeasible for embedded control, therefore concepts using fixed time-step methods are required. However, standard fixed step approaches may induce unwanted oscillations at locking events of friction elements. The proposed approach overcomes this limitation and permits embedded execution at rates common to automotive control units. Although locking friction elements influence the mechanical degrees of freedom, which leads to a switched system, one single observer gain matrix suffices for the novel observer concept. Asymptotic stability of the estimation error is shown based on Lyapunov theory. Finally, the proposed observer is validated using vehicle measurement data.

Real-time dynamic drivetrain modeling approaches have a great potential for development cost reduction in the automotive industry. Even though real-time drivetrain models are available, these solutions are specific to single transmission topologies. In this paper an environment for parameterization of a solution is proposed based on a generic method applicable to all types of gear transmission topologies. This enables tool-guided modeling by non- experts in the fields of mechanic engineering and control theory leading to reduced development and testing efforts. The approach is demonstrated for an exemplary automatic transmission using the environment for automated parameterization. Finally, the parameterization is validated via vehicle measurement data.

This article opens perspectives for generic modelling and real-time simulation of automotive gear transmissions containing multiple friction elements. Generic mathematical drivetrain modelling is challenging, as friction elements cause a system to vary its order and structure. Furthermore, adaptive time-step methods are not suitable for real-time simulation. Unfortunately, literature lacks flexible fixed time-step approaches for multiple friction elements. The modelling solution proposed in this article is designed for fixed time-step execution and is applicable to all types of gear transmissions. The approach is verified on an exemplary simplified drivetrain. It is demonstrated on a complex hybrid-electric automatic drivetrain topology and validated via transmission test bench measurement. Finally, the approach is applied to a conventional automatic drivetrain and validated via vehicle measurement.

Efficient coordination of actuating elements is an important challenge for modern automotive control units in order to deliver the requested torque for propulsion during all driving conditions. Model-based approaches have large potential to deal with the growing complexity. The need for real-time execution leads to fixed time step solution of the model equations. Solving model equations containing friction elements is a major challenge, since adaptive time step methods involving zero crossing detection are not feasible for real-time execution. This publication focuses on a technique for modeling complex drivetrain layouts that contain several friction elements like clutches and brakes. The main target of this contribution is to loosen requirements on maximum time step size which arise due to discontinuous friction modeling within the model equations. The proposed approach enables model-based calculations at larger time step sizes. This permits online calculation of complex gear transmission models at usual time rasters of common automotive control units.

This article proposes a technique for fixed timestep state observation of automotive gear transmissions containing multiple friction elements like clutches and brakes. As adaptive time-step methods are not feasible for embedded control, the solution of model equations containing friction elements is a major challenge. The suitability of the proposed approach for a complex gear transmission comprising multiple friction elements is demonstrated by modeling and fixed timestep simulation. Based on that model, a fixed time-step proportional integral state observer is derived, that permits embedded execution at execution rates of common automotive control units.

In current vehicles the actual value of engine torque is provided as interface signal to powertrain control units. For transient operation the dynamic behaviour of the combustion engine has to be estimated e.g. in the transmission control unit in order to coordinate the powertrain components. Due to the lack of provided data on the dynamic behaviour it needs to be modelled separately in each control unit, mainly map-based with high calibration effort.The engine control unit (ECU) has access to the relevant sensor and reference values for online calculation of diesel engine dynamics. Within this publication a model-based online torque calculation is proposed taking into account information that is already available in standard ECUs. Additionally the current torque reserve is computed. The calculation of characteristic parameters defining the dynamic behaviour for torque requests is outlined.Based on these signals prediction of engine dynamics is simplified and can significantly reduce the calibration effort e.g. in transmission control unit. The presented paper describes the calculation method and compares simulation results to engine test bed measurements for validation.

An important target for automated transmission development is driveability during the launch process of a vehicle. For transmissions using launch clutches the friction energy has to be considered to avoid thermal breakdown. The launch process is controlled by electronic control units containing functions tunable by parameters. Optimizing those parameters can be time-consuming when testing on a real vehicle. Using a simulation model as input for evaluation of the objective function can lead to significant cost savings as well as shorter development time in automotive applications. In this work we contribute a lean mathematical model of a vehicle’s drivetrain tailored for optimization of the launch process. The model includes combustion engine, inertias, clutches, flexible shafts and control algorithms for engine and clutches. The two design parameters clutch closing time and scaling factor for clutch slip speed are chosen to optimize the objective function taking into account driveability and clutch friction energy. As the objective function is nonlinear and not even continuous, we propose using a DE approach, which does not require the knowledge of the objective function’s gradient. To further improve optimization results a surrogate objective function is built using a radial basis function approach. Found optimal parameters for clutch closing time and scaling factor for clutch slip speed shall be applied to a prototype vehicle as initial parametrization. Within this paper a realistic launch simulation with optimized parameters is shown. Furthermore the suitability of a DE approach for the given task is demonstrated.