CAN-based 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.
