HANOVER, Germany — With an eye on improving the braking performance of passenger tires, Continental A.G. has designed a driverless test vehicle that can measure tires' frictional properties independent of individual vehicle models.
The objective of the automated test is to improve the frictional grip properties of tires and thus reduce vehicle braking distance further to ensure greater road safety, Conti said.
The driverless test vehicle uses a drive system incorporating two electrically driven axles powered by a high-performance battery. The system's high maximum torque ensures that a constant speed can be maintained, Conti said, while the test tires on the third axle can be braked systematically.
The AVA —– "Analytic Vehicle AIBA" — enables precise monitoring of the frictional properties of tires during braking maneuvers on dry and wet roads, Conti said.
Conti said this development allows it to combine the advantages of a test method that is independent of the vehicle model with the controlled and reproducible test environment of the company's Automated Indoor Braking Analyzer (AIBA), which has been in use at the company's Contidrom testing facility since 2012.
"Our analytic vehicle AVA helps us to analyze the performance of our premium tires in even greater detail and systematically develop them," according to Boris Mergell, head of research and development at Continental's Tires Group sector.
The transmission of forces between the tire and the road surface is decisive for tire braking performance, Conti said, as well as for cornering characteristics or when changing direction.
"The performance of the tire during braking is essential for the safety of the vehicle. For this reason, we make great efforts to analyze our tires as precisely as possible," Mergell said.
For the tire braking tests, the AVA is accelerated to a test speed of 40 mph (65 km/h) with the aid of an electromagnetic linear drive, which is derived from modern roller-coaster technology. Then, several fully automated braking tests are carried out.
The integrated braking system of the AVA is equipped with brake-by-wire technology from Continental's Automotive business sector. Unlike conventional hydraulic braking systems, the braking signal is transferred electronically, yielding a quick, precise reaction, which is essential for accurate testing or measuring.
"Our AVA determines the transmission of forces between the tire and the road surface, while various slipping states, so-called "µ-slip curves", are precisely reproducible," Meletis Xigakis, responsible for global tire testing at Continental, said.
"With the state-of-the-art measuring technology we measure all of the forces that act between the tire and the road surface during braking. We can compare our tires and their various compound compositions even more precisely and optimize them for their special uses," Xigakis said.
The AIBA features a 245-foot-long test track housed in an air-conditioned area of the test hall, which has up to five road surfaces that can be exchanged hydraulically. In the weather-independent facility, up to 100,000 braking tests can be performed annually on dry, wet or even icy roads.