Driver Assistance Systems: General Inspection for Sensors
Author: Michael Vogel
As driver assistance systems become increasingly prevalent in vehicles, who ensures their continued and reliable performance - even with tens of thousands of kilometers clocked?
General inspection is an integral part of every vehicle's life cycle, yet there are significant differences in local regulations around the world. Whilst vehicle safety is paramount, many countries now also include emission testing as a standard part of the inspection. Just as automotive technology has evolved over the decades, vehicle inspection also has to adapt to new technological developments. With the increasing number of vehicles equipped with driver assistance systems, this development is set to continue.
"In the EU, inspectors already check for visible damage or improper repair work around driver assistance system sensors as part of the general inspection," Thomas Ost, responsible for service development at DEKRA vehicle testing, explains. “Furthermore, any defects or limitations stored in the vehicle's fault memory or displayed on the dashboard are documented.” Testing components such as wheels, tires, brakes, and steering, which has been a standard for decades, also have an indirect impact on the reliability of the electronic assistance systems. "Even the best systems are useless if the brakes are not working properly, or the tires are worn."
DEKRA is developing a new test method for sensors
However, DEKRA wants to go beyond that in the future, and is committed to ensure that the increasing amount of technology and software in vehicles is given greater consideration during general inspections. "We have developed a demonstrator that can be used to test the sensors of driver assistance system quickly and effectively," says Ost. To be more specific, this concerns radar sensors installed in the grille or behind the bumpers. They are used by emergency brake assistants, lane keeping or cruise control systems. Rohde & Schwarz and AVL DiTest were involved in the development of the demonstrator. The process can be used to test the function of the radar sensor when the vehicle is not in motion.
This is how it works: a simulation device imitates various objects to the sensor, such as other vehicles, people or objects. Distance, direction of movement, and the speed of these objects are then identified. While the radar sensor detects the simulated object, a test engineer is then able to access information via the vehicle diagnostics interface. What they see is what the driver assistance system perceives and, consequently, what action this would trigger – an emergency brake application for example. Using this method, the function and proper sensor calibration can be checked. Within the project, Rohde & Schwarz designed the simulation device and AVL DiTest provided the vehicle data extraction. DEKRA developed the general concept, specified the requirements, and orchestrated the whole process.
"Sensors are particularly susceptible to wear, misalignment, and other impairments," Ost notes. This principle can easily be applied to other sensor technologies. "We have designed the demonstrator with a specific focus on radar sensors as they are currently the most common type of sensor used in vehicles," he continues. "Optical cameras and, in future, lidar sensors would be suitable for a similar approach." Alongside the simulation, the approach envisages a software test. "First and foremost, the question is whether the driver assistance system's software version installed is actually type tested and approved," says Ost. "Another component of the test is checking safety mechanisms to rule out any manipulation and checking the data contents within the software."
Focusing on software and sensors makes this test scenario a simple one
DEKRA's approach is not the only proposal currently being debated among experts. "What puts our technology ahead is that it could easily be integrated into headlight adjustment checks in a workshop, for example." Neither high investments nor a lot of space is required here. The focus on sensor technology and software makes complex test scenarios with expensive equipment on special circuits redundant. "Our approach doesn't demand excessive effort by anyone involved," says Ost.
In addition to mere regulatory aspects, implementing this approach requires certain changes to the vehicles. "The three measured values—distance, angle of movement, and object speed—should be easily accessible in a standardized manner, via an established vehicle diagnostic interface, for instance," Ost explains. "Driver assistance systems only function properly while the vehicle is in motion, whereas during inspection, the vehicle is stationary. Thus, the vehicle must be capable of entering a test mode." Vehicle manufacturers would therefore be affected, as would type testing. It would take a while for the functionalities to be implemented in production vehicles as corresponding regulations would have to be made in Europe at EU level. However, such impediments do exist for all existing proposals regarding the future testing of driver assistance systems – inevitably, data access is a prerequisite.
Presenting the project to global experts
DEKRA and the aforementioned project partners are currently showcasing their approach to experts from all over the world. A field test in a designated test hall will commence shortly. "Practitioners who were not involved in the development will then test the system on different vehicles," Ost provides an outlook. A joint project with FSD GmbH is also in the pipeline at the DEKRA Technology Center in Klettwitz, in the German state of Brandenburg. FSD is state commissioned to draw up standardized inspection specifications for general inspections. As part of the project, participants plan to misalign or otherwise interfere with driver assistance system sensors in a controlled environment to determine how their function is affected. Causes range from everyday incidents such as parking bumps, rock chips on the wind screen to improper repairs. "In Klettwitz, we will be able to gather valuable insights into which degree of damage will actually impact safety and functionality," Ost concludes.