Felix Pfister

A model-based interfacing concept for accurate power hardware-in-the-loop systems

This article introduces a novel concept for the interface of power hardware-in-the-loop (PHiL) test systems. In a PHiL system, a real device under test is connected to dynamic simulation models that emulate high power flows running to and from the device under test. The states of these dynamic models are thus used to physically actuate the real hardware component and likewise the states of the latter serve as an external excitation of the dynamic model. Thus, a PHiL system constitutes a complex interaction of dynamic mathematical models and real hardware components. The purpose of PHiL systems is to operate and test the hardware component as closely to its future designated environment as possible. A crucial factor for a highly accurate PHiL system lies in the interface between virtual dynamic simulation and the physical hardware. Accuracy and performance is often impaired by signal communication delays, sensor noise and insufficient performance of test bed control systems. The approach presented in this article reduces unwanted oscillations based on an online receding optimization of specific state variables in the dynamic simulation environment. In addition, the adherence to physical conservation laws is assured. The interface algorithm makes use of an online model which incorporates knowledge about the dynamics in the underlying simulation. The performance of the proposed methodology is demonstrated and discussed by means of a highly dynamic automotive powertrain PHiL test bed in combination with a complex multibody real-time vehicle simulation.

TEODACS : A new vision for testing dependable automotive communication systems

Cars are forming complex distributed architectures implementing optimized networks. Evidently, the communication plays a central role for the dependability and the performance of the system. This document presents the challenges and vision of the newly started TEODACS research project. Our aim is to consider the communication services as a whole and to study the internal (e.g. configuration) and external (e.g. EMC) effects that influence the network and further the system performances. We discuss how our consortium ideally supports this approach and we introduce the projectpsilas vision based on the close development of a laboratory setup as well as a simulation framework.

Total energy efficiency testing

Individual mobility today implies — in addition to comfort and safety — above all energy efficiency. An energy-efficient vehicle places high demands on automatic control systems because the functions are often divided up on to many controllers and the objectives defined in the requirements specification can only be achieved by means of optimized interplay between the controllers. So the further development of the classical chassis dynamometer into a powerful “vehicle-in-the-loop” test bed as pursued by AVL is a logical consequence. This article describes how a chassis dynamometer becomes a mecha tronic development platform and helps automotive engineers to put “green” technology on the road in a cost-efficient and rapid manner.

Effizientes Testen für mehr Energieeffizienz

Individuelle Mobilitat von heute bedeutet — neben Komfort und Sicherheit — vor allem Energieeffizienz. Ein energieeffizientes Gesamtfahrzeug stellt hohe Anforderungen an die Steuerungs- und Regeltechnik, da die Funktionen oft auf viele Steuergerate verteilt sind und sich erst im optimierten Zusammenspiel die im Lastenheft festgelegten Ziele erreichen lassen. Die von AVL beschrittene Weiterentwicklung des klassischen Rollenprufstands hin zu einem leistungsfahigen „Vehicle-in-the-Loop“-Prufstand ist daher eine logische Konsequenz. Wie der Rollenprufstand zu einer mechatronischen Entwicklungsplattform wird und den Automobilentwicklern dabei hilft, „grune“ Technologien kosteneffizient auf die Strase zu bringen, lesen Sie in diesem Artikel.

Energy Flux Simulation on a Vehicle Test Bed for Validating the Efficiency of Different Driving and Assistance Systems

Legislation claims a sustainable handling of existing resources. For this reason all newly registered vehicles must emit less then maximum 130 g/km CO2 on average by 2015. Car manufactures are therefore forced to use new approaches in the fields of propulsion technology and assistance systems. For the development of such efficient vehicles new methods are needed which exceed the determination of the consumption at the chassis dyno or the road test. It is necessary that the results concerning the real consumption as well as the distribution of the energy losses are available at an early stage of the development cycle. Furthermore, the safeguarding of the functionality of new highly networked powertrain systems is an important aspect. Here, the energy flux analysis at the vehicle test bed comes into place. As integrated validation environment it will be referred to as Function and Energy Flux Simulator (FES). With FES, real driving situations are emulated by means of a vehicle dynamics simulation. With dynamometers the occurring wheel torques are impressed on the vehicle. At the FES, driving scenarios and the environmental conditions are exactly reproducible so that the results are significant. In addition, a continuous superordinate process for validating the energy efficiency which reaches from the office simulation to the trial at the test bed as well as to the road drive with portable measurement systems was set up.