CAN Newsletter special issue automotive

Controller Area Network in-vehicle networks

Controller Area Network (CAN) was originally developed for power-train applications. Nowadays, there are additional applications in cars that make use of this 20-years old network technology. In nearly all of the European cars, the chassis network and the body networks are based on CAN. Even in the information and entertainment applications, sometimes CAN networks are used to control the devices or to provide an interface to the information that is already available in other CAN-based in-vehicle networks.

Power-train networks

The shift from mechanical to primarily electronics- and-software-based vehicle innovations started with the introduction of networked power-train ECUs. In the beginning three network technologies competed: A-Bus, CAN, and VAN. The A-Bus invented by the Volkswagen group and the French VAN (Vehicle Area Network) did not survive. Nowadays, CAN is used in Europe, America, and Far East. Just a few car models are not equipped with CAN network connecting the power-train ECUs.
There are still new developments in power-train applications. Quieter engines, less fuel consumption, cleaner exhaust, and better driving dynamics are sometimes contrary demands that can only be met when closed-loop software is enhanced and CAN communication is optimized. An example of what can be achieved, is the power pack from Bosch used in the GL-class from Mercedes-Benz.

Active vehicle safety systems

Seatbelts and airbags are the most successful passive vehicle safety systems. No doubt, they have saved many lives. The success story of active vehicle safety systems started with the electronic stability program (ESP) introduced by Bosch after a car from Mercedes had not passed the so-called ‘elk’ test. Electronic stability control (ESC) is the product-neutral term. ESC systems can detect unstable driving situations and make an automatic correction to protect the driver from losing control. The system compares the driver’s intended course with the vehicle’s actual movement using a complex system of sensor that measure wheel speed, steering-wheel angle, yaw rate, and lateral acceleration. This information is made available by several ECUs and communicated via the already installed in-vehicle CAN networks. If the ECS detects that the driver is losing control, it uses a combination of anti-lock brake (ABS), electronic force distribution, and active yaw control to stabilize the vehicles and help keep it on the road. The actuator commands are communicated to the ECUs via CAN networks. Continental, a company that makes more than tires, is developing the ESCII system. It monitors active steering control functions and is part of Continental’s Total Safety concept.

Control prototyping and hardware simulation

In the future nearly all innovations in automotive will be based on the employment of mechatronic systems, since an optimization of the system performance is possible only by the use of electronics and software. A substantial aspect with the development of mechatronic systems is the systematic proceeding in the development process, which is optimally supported by the consistent employment of integrated software and hardware tools. Development tools of The MathWorks allow a high degree of automation in the development process, which ensures constant reproducibility.
However potential for the improvement of the process still exists, e.g. by extension of the tool chain. This article describes tools specially developed for real time applications. Embedding them into the overall process causes a further reduction of development time and cost.

The V-model

With the help of simulation techniques a model-based function development takes place in the environment Matlab/Simulink. A software model is produced, which simulates the dynamic behavior of the system under development. Already in the early design phase reciprocal effects of the individual components can be analyzed. Then algorithms are developed on the basis of this analysis, which represent the desired total behavior of the software model. As a result optimal algorithms for regulating and controlling are available, which are used as specification for the prototype to be realized.
The next step of development is the rapid control prototyping (RCP). Here the prototyped algorithm is automatically implemented and tested on efficient real time hardware. The prototype can be integrated both into real and virtual environments. The latter takes place e.g. in the context of a hardware in the loop (HIL) simulation.
Subsequently, the generation of serial code takes place. The source code for prototype and series controllers is produced from the model by the use of automatic code generators.

Automotive electronics take off

Strategy Analytics released results of an in-vehicle networks study. In 2005 more than 400 million CAN controller chips were sold. The estimated figure for 2010 is about 800 million. In 2004 the value of all in-car automotive electronics was 6,9 billion US-Dollar, this will increase to 25,9 billion US-Dollar in 2009 according to the ZVEI (the German Electrical and Electronic Manufacturers’ Association). This indicates that electronics in automotive applications increase considerably. The carmakers spend much effort in the development of new passive and active safety functions. This requires a lot of new electronic control units (ECU), smart sensors and actuators. The University of Applied Science Bergisch-Gladbach published a study on car innovations. Most of the innovations in 2005 were initiated by General Motors (about 50%). However, DaimlerChrysler made the most significant innovations, and Toyota is number one in applying for patents. In particular, the active safety systems will drive the automotive electronics. Strategy Analytics expects an annual turn-over of 57,8 billion US-Dollar in 2012, which is optimistic. The active safety systems with an annual average growth of 12,3% will have a volume of 8 billion US-Dollar in 2009. The market research experts from Frost & Sullivan forecast a higher annual growth rate for safety systems. The chipmakers are competing heavily for shares of the above-average growing automotive electronics market. The total available market in 2005 was 16,4 billion US-Dollars. Last year, Infineon increased its sales figures by 11,9%. The company is number one in Europe and number two worldwide. The largest chipmaker for the automotive industries is Freescale followed by Infineon, STMicroelectroncis, Renesas, NEC, Toshiba, Philips Semiconductors, and Bosch and many others. The number of CAN chips can easily be calculated: The total annual production of cars is about 55 million units. The premium cars are equipped with up to 80 CAN-connected ECUs, and the compact class uses just a few. In average a passenger car implements ten CAN connected ECUs, which results in about 500 million of CAN interfaces. Frost & Sullivan expect that there is no competitor to CAN for intelligent sensors and power-train ECUs. This means CAN sales figures will still increase. The ZVEI forecasts 73,9 million new cars for 2009. The sales figures for in-vehicle electronics are predicted as 25,9 billion US-Dollar. Even if the average number of CAN devices per car does not increase, about 800 million CAN chips will be installed in 2009.