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Open source bus

Two layers reduce complexity

To build secure systems in cars, a German research project has developed a two-tier IT architecture: one layer for vital functions, and one for comfort functions. The system will become open source.

A central screen provides driving information; with swiping gestures the driver can enter commands on a touch pad (Photo: Florian Lehmann / TUM)

UP TO 80 DIFFERENT DEVICES COMMUNICATE in many cars. The complexity has come to a limit. Within the Visio.M research project, funded by the German Federal Ministry for Education and Research with a total of €7,1 million, scientists at the Technische Universität München (TUM) have developed a two-tier IT system that reduces this complexity. The researchers put their Automotive Service Bus under an open source license.

Cars are starting to resemble computers more and more. Increasingly, breakdowns result from the electronics. In the near future, cars will probably communicate via the Internet and drive via remote control or even autonomously.

For Visio.M, scientists at the TUM have developed a new IT architecture. Akin to smartphones, it is structured in two layers:
All driving and safety relevant functions run in one layer, while comfort functions, as well as communication between system, driver, and internet are located in the other.

The system is protected from external attacks by running the two subsystems on different platforms. All vital functions are managed by a central electronic control unit (ECU) with a CAN network. A web-enabled computer is responsible for driver and Internet communication. Its basic architecture principle builds on the Automotive Service Bus developed by the researchers.

News exchange on the bus

The Automotive Service Bus functions as a message channel. All components can send and receive messages via this channel. The components have only read access to vehicle data, which is essential for security. Only in clearly defined situations for predefined functions, the central ECU grants write access. This allows, for example, the implementation of a remote control for a car.

In principle, there are three different kinds of messages: Events provide information like current speed or position. Commands allow interactions between individual components, like setting a new target temperature for the air conditioning system. Preferences are messages with driver-specific information like music preferences or a home address.

“All components must adhere to the grammar of the Automotive Service Bus, that’s all,” says Michael Schermann, director of the Automotive Service Lab at the Chair for Computer Science in Economics at the TUM. “Just like apps on a smartphone, components can be updated, appended or deleted without having to visit a service station.”

The architecture of Visio.M (Photo: TUM)

Uniform user interface

A graphical user interface (GUI) facilitates the communication with the driver. All essential driving information is displayed on a central dashboard screen. “The display on this screen can be designed as needed,” says Michael Schermann. “In Visio.M, we chose a rather classical display design with round instruments.”

A center-mounted touchscreen accepts driver input. To minimize distractions while driving, the unit accepts simple swipe gestures. In contrast to smartphones, there are no elements that must be accurately “hit” with the finger. If components are added or altered, the GUI remains largely unchanged. Additional or different functions simply become available. On the other hand, users can adapt the GUI to their personal preferences without any work on individual components.

While cars of the past could hardly be altered over their entire lifespan, the separation of the two layers allows updates and adaptations to be made at any point in time. “The Automotive Service Bus also forms an ideal basis for premium services. For example, for a small additional fee, personal music collections stored in a cloud can be made available to rental car drivers,” says Michael Schermann. “And if I prefer the navigation program of a specific provider, the system can make this service available – without changes to the vehicle.”

Bus becomes open source

Equipped with this system, Visio.M received its official road-use certification in October 2014. Following the end of the research project, the developers at TUM are now making the Automotive Service Bus available under an open source license. “This will provide developers around the world the opportunity to use this platform for their own research,” says Michael Schermann.

The OSGi software platform (Open Service Gateway Initiative) forms the basis of the Automotive Service Bus. It is Java-based and, as such, runs on operating systems like Windows, Linux, or Mac OS. The hardware platform is a Panda Board, a single board computer based on a chipset of the partner company Texas Instruments, running a Linux operating system. An Apple iPad serves as a touchscreen. The central control unit is an ECU of the partner company IAV.

Scientists and engineers work together

Within the joint research project, scientists at TUM develop - in cooperation with engineers from the automotive industry - concepts to produce electric cars that are efficient, safe, and inexpensive. The consortium partners use an electric vehicle prototype called Mute, which was developed by the TUM, to explore innovations and new technologies for vehicle safety, propulsion, energy storage, and operational concepts for implementation under the framework requirements of large-scale production. Special attention is given to safety-related design issues.

Participants in the Visio.M consortium were, in addition to the automotive companies BMW AG (lead manager) and Daimler AG, the Technische Universitaet Muenchen as a scientific partner, and Autoliv, the Federal Highway Research Institute, Continental Automotive, Finepower, Hyve, IAV, InnoZ, Intermap Technologies, Lion Smart, Amtek Tekfor, Siemens, Texas Instruments Germany, and TÜV SÜD as industrial partners. The project was funded under the priority program "Key Technologies for Electric Mobility – Strom" of the Federal Ministry for Education and Research for a term of 2,5 years with a total budget of €10,8 million.