By David Shaw ERJ staff
Hannover - Continental has unveiled a new automated brake test facility at its ContiDrom tyre proving ground near Hannover. The facility offers fully automated, driverless testing of braking performance on a variety of surfaces, including ice. The road surfaces and the ambient environment are both fully climate-controlled.
The aim of the euro 12 million facility is first to improve the repeatability of braking tests; second to relieve pressure on human test drivers and third to ensure tests can be carried out 24/7 irrespective of weather or other external factors.
The facility, known as AIBA (Automated Indoor Braking Analyzer), is now fully complete, but will not be producing active results for another few months while the road surfaces stabilise. However, even in simulated tests performed for financial analysts and journalists, the system delivered remarkable repeatability. In eight runs, the start speed varied from 84.78 km/h to 85.10 km/h and the braking distance (80 km/h - 20 km/h) varied from 25.70m to 26.37m. Conti said it confidently expects the facility to deliver braking repeatability to better than +/-0.2m compared with around +/-1.2m using existing systems with human drivers.
The system draws on roller coaster technology. Vehicles are moved around the facility using a rail similar to the rails used by rollercoasters. Vehicles are launched to a maximum speed of 120 km/h using a linear motor which is capable of accelerating a vehicle up to 3,5 tonnes to the maximum speed in around 5 seconds - or around 2.5g. In practice, however, the system is de-tuned to deliver a maximum acceleration of 0.6g which his comparable with the take-off acceleration of a commercial airliner.
Engineer Cord Spenger who originally developed the idea said the project is cost-neutral. Savings generated by reductions in costs of test drivers; reductions in shipping tyres and other equipment to overseas test tracks; savings in hiring ice rinks and suchlike can offset the capital and operational cost of the facility. He said the whole project began almost exactly 2 years ago.
The facility is some 300m long. The active area of the facility involves a 100m acceleration phase with the linear motor and a 75m deceleration section. The full 75m section of test surface can be moved and replaced. Each 75m long concrete, steel and asphalt cassette is stored in a soak room where it can be adjusted to a specified temperature prior to use. The ambient temperature can also be adjusted with great accuracy.
Currently the facility can store three 75m long cassettes. One of these can be positioned outdoors as part of a separate test track. Conti aims to see if weathering due to sun, rain, snow and other elements makes a difference to the road surface. The outdoor area is also used to re-lay the asphalt or concrete surface on the cassette. The main indoor test track cassettes can be changed from one to another in around 8 minutes.
The ice facility is not part of the fully automated facility, but runs parallel with that track. Vehicles are tested using conventional test drivers. However, it is an advance on conventional ice rinks as the cooling system has been designed to maintain an even ice temperature down the track. Conventional ice rinks involve only one or two cooling units. This means the ice temperature varies from the centre to the edge. The Conti facility has multiple cooling units. The ice temperature can be controlled between -10C and -1C. The ambient conditions can be varied between 5C and 12C. Conti said this enables the company to evaluate the critical conditions as the ice is approaching its melting point. The surface is thick enough to accept studded tyres as well as more conventional cold-weather tyres.
Conti said the facility can run up to 15 tests per hour, 24 hours a day.
More on this story in the coming issue of ERJ