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All wired up

DaimlerChrysler has initiated a competence centre for electronic architectures at the Technical University of Dresden where students have the opportunity both to acquire theoretical knowledge and to gain practical experience. It is a form of cross-breeding that has had some consequences of its own. Adrian Goodsell reports.

	The students at the Technical University of Dresden quickly applied their newly acquired knowledge about electronic architectures and mechatronic systems to a practical project: the creation of the research vehicle August
	This three-wheeled research vehicle is modular and has been built according to new principles. It can be steered with a steering wheel, a joystick or a remote control
	At the end of the 1940s, the electrical system was restricted in principle to the lights and starter. The Mercedes-Benz 170 V got along with 40 cables, and its cable system was correspondingly simple

August is certainly not handsome. If he faced off against the competition at one of the major international automobile shows, the visitors would pass by without casting a glance in his direction. With no bulging muscles that he can flex and no breathtaking outfit that will magnetically attract people’s attention, August is easily overlooked.

However, first appearances can be deceiving. In fact, the three-wheeled car, which looks as if it has just been pulled out of a metal construction kit, is probably the year’s most unusual test vehicle. August was born in the eastern German city of Dresden. His creators — students at the Technical University in the city — named the vehicle after the famous king August the Strong of Saxony.

New principles of building

It is essentially two features that make the plain-looking August so unusual: his creation in a practice-oriented university course and the topical ground which the Dresden vehicle covers.

August is the world’s first teaching and test vehicle to be built strictly according to new principles. With August, the up-and-coming generation of engineers not only can explore the principles behind electrical and electronic architectures (EE architectures) but also can try out their own research ideas and concepts.

“EE architectures describe the quantity and design of electrical and electronic components in a vehicle as well as their relationship to one another,” says Prof Peter Hofmann, an information technology specialist heading a working group called Theory of EE Architecture at DaimlerChrysler. “They are usually represented in the form of block diagrams.”

Defining electronic architectures

Over the past 50 years, the structure of a vehicle’s electrical system has changed little in principle – cars are equipped with a generator and a battery that supply electricity to various consumers via a series of wires and switches.

In the beginning, it was only necessary to power the starter, headlights and the indicators. As time passed, other features such as the windscreen wiper motor, electric window lifts and air conditioning were added. As these features increased over the years, the amount and length of cables required to provide them with electricity also grew.

Where a Mercedes-Benz only needed 40 cables in 1947, by 1979 an S-Class was being fitted with around 1,900 pieces of wire. The total length of connecting cable laid out would have stretched over some three kilometres.

Today, the electronic systems have assumed a dominant position. Besides conventional electrical systems, vehicles are fitted with an array of bus systems with dozens of electronic control units for the drivetrain, chassis, interior and telematics. In this context, the term “wiring harness” is a drastic understatement — “wiring jungle” would be a more fitting expression.

Maintaining a view of the big picture within this jungle involves not just the spatial challenge of fitting an increasing number of components into a restricted space. The task is further complicated by the fact that electronically controlled systems like ABS and ESP have to co-operate reliably with one another even though their operating principles are different.

“The vehicle’s electrical and electronic systems are converging, as are its mechanical components,” says Hofmann. “That’s why we have to redefine the electronic architectures and make them transparent.”

Making conceptual structures visible

To make his point clear, Hoffman draws a parallel with the architecture of buildings. On the one hand, this type of architecture is immediately perceptible to the senses, while on the other its spatial organisation reveals the conceptual structures that lie behind it. “In a similar way,” he says, “the electronic architectures have to have a clear organisational principle that is reflected in their spatial structure.”

In concrete terms, this means that instead of grafting a few more components onto an existing structure and running a few more cables through the car as has been the case up until now, flexible and expandable “spatial blueprints” need to be devised for future vehicle electronic systems. This will allow individual modules to be easily installed and removed. Ideally, these modules will be mechatronic components that combine mechanical control elements and electronic control components in a way that saves space and increases reliability.

In the laboratory, it is difficult to develop the kind of modular superstructure in which the various mechatronic systems interact.

To Hofmann and his team, the best approach therefore seemed to involve the testing of their newly developed EE architectural concepts directly in a vehicle. “That’s how we came up with the idea of building an electric vehicle that is not only equipped with mechatronic modules, but can also be used to develop and test current and future automobile functions,” says Hofmann.

At first, the research team developed this idea in a laboratory vehicle whose modular design literally makes its EE architecture — which is based on current vehicle technology — visible and tangible.

The benefit of transparency quickly gave the scientists another idea – building a mechatronic vehicle together with students. The Technical University at Dresden was the obvious choice because DaimlerChrysler has been working with the college for a long time.

Step by step approach

“The students should get to know mechatronic concepts and the underlying mechanisms governing the development of electronic systems,” says Hofmann’s colleague Volker Dohmeyer when explaining the aim of the lectures and the accompanying exercises. “Moreover, they should do so both in theory and practice.”

Following the lectures given by the DaimlerChrysler researchers, the students applied their new knowledge in practical exercises and homework assignments. By the end of the semester, the teaching and research vehicle was finished.

The mechatronic August consists of a base and a body module. The base unit includes the drive system with two three-phase synchronous motors that are equipped with an electromagnetic spring-force brake, an emergency stop function, the steering system, the network, the cables and the power management system. The latter uses a microcontroller and computer to regulate the interaction of all electronic components — in other words, motors, the battery, charger, power supply and relay.

The body unit has both a steering wheel and a joystick that can control the drive and steering, and — keeping the driver’s comfort in mind — the seat controller. Here, the students had to rebuild the seat adjustment switch and the seat control unit according to mechatronic principles.

The driver’s seat from the S-Class served as an instructive test subject. The inside of the seat houses six servo motors, the seat heating unit, the seat air conditioning with 15 fans, the electronic memory for the seat adjustment, various sensors and the control unit.

The functions of the base and body units were worked out and checked by separate groups of students. Once they determined that all of the mechatronic elements functioned both individually and when interacting with one another, nothing else stood in the way of final assembly and the roll-out of the teaching and test vehicle.

Modern EE architecture means transparency and modular design

Carmakers have a problem – they do not have the specialists who can implement electrical and electronic architectures in practice. The university courses offered in this subject are largely theoretical. In an effort to link this scientific education more closely with the real world, DaimlerChrysler has set up co-operative arrangements with several universities. In one of these projects, the company has established an EE architecture competence centre at the Technical University of Dresden.

In mid-2002, Prof Günter Hertel, the head of the directorate Research Electronics and Mechatronics (REM), and Alfred Post, chancellor of the Technical University of Dresden, came up with the idea of creating a new type of co-operation project that could be quickly implemented in practice.

The competence centre’s main tasks lie both in education and the development of new types of EE architectural concepts for vehicles of the future. In the short term, the scientists want to evaluate “state-of-the-art project methods for distributed EE systems in the car.” In the long term, they plan to develop “self-optimising project methods for EE architectures” and turn them into prototypes. The competence centre is part of the Department of Transportation Sciences “Friedrich List.” Most of the employees are from the Technical University of Dresden. Scientific leadership is provided by Prof Peter Hofmann, who heads the department of EE Architectural Theory at DaimlerChrysler research.

Hofmann and his team work closely with the vehicle electronics and electrical systems department, which is chaired by Prof Hans-Christian Reuss. During a joint series of lectures and seminars held during the past winter semester, about 50 students learned the basics of electronic architectures and mechatronic systems — and put their knowledge directly to practical use in the “August” vehicle.