Rear-end collisions are the most common types of accidents. The causes range from inattentiveness when the car in front slows or stops; distractions such as mobile phones, eating or adjusting the radio; poor visibility; inadequate distance etc. While most rear-end collisions in city traffic mostly result in minor vehicle damage, collisions on the motorway often result in serious or fatal injuries.
ADAC, Europe’s largest motoring organisation, has conducted extensive research into advanced emergency brake systems. These auto brake features are already built into many new vehicles in order to prevent or mitigate the consequences of collisions. The new vehicles include radar sensors, camera or lasers which are able to recognise objects in front and alert the driver if a collision is imminent. Advanced emergency brake systems can brake the car automatically in order to reduce the impact speed or prevent the crash altogether.
10 car models each undergo a series of tough tests
ADAC has tested 10 different vehicles in order to assess their capability to initiate braking where a collision is imminent as well as when and how effectively the driver is alerted to a collision. The vehicles tested included a BMW 750i, Mercedes C-Class, Volvo V40, VW Touareg, Audi A6, Lexus GS, Opel Insignia, Honda Civic, Mercedes B-Class and a Ford Focus.
All ten cars tested by ADAC were put through five tests:
- Approaching a stationary vehicle over a range of speeds ( 70, 50, 40, 30 and 20km/h)
- Approaching a slower vehicle (Hunter 50km/h and Target 20km/h; Hunter 100km/h and Target 60km/h)
- Approaching a target vehicle travelling at 50km/h which suddenly brakes
- Approaching a target vehicle which is travelling at the same speed (60km/h) and then slowing down
- Adaptive brake assist – driver brakes insufficient (Hunter 50km/h, Target 0km/h; Hunter 80km/h, Target 20km/h)
ADAC Target – Collisions without the vehicle damage
German motoring organisation ADAC uses a specially designed balloon target which replicates the rear of a normal passenger car. The ADAC Target can be towed behind a real car with a unique propulsion system. The ADAC Target can be used for longitudinal front-to-rear collisions between two vehicles without causing costly damage to the vehicles tested.
Cutting-edge measurement systems
In order to quantify the results, ADAC equipped the cars with some cutting-edge pieces of technology: a Vehico braking robot, CAN data acquisition software from Stiegele, an Audiovisual Alarm Detector, and two highly accurate RT3002 GPS-aided inertial navigation systems from OxTS as well as the OxTS RT-Range system.
The braking robot was used in order to create identical test conditions for all vehicles. By eliminating the influence of a human driver applying force on the brakes, the vehicles can be tested with highest accuracy and maximum repeatability. The robot brakes at a pre-defined point but doesn’t apply enough force to avoid the collision at which point the adaptive brake assist steps in.
At the heart of the tests is the OxTS RT3002 – a highly accurate measurement system which is able to output the position of the car with 2cm accuracy, and measures heading (0.1°), velocity (0.05km/h) as well as other parameters. The RT3002 is used in combination with the RT-Range system which was specially developed to test and verify advanced driver assistance systems. The RT-Range consists of a Hunter and one or more Targets. With the RT-Range vehicle-to-vehicle measurements can be output by measuring the position of the vehicles and then transmitting the position of the Target(s) to the Hunter using wireless LAN radio.
RT-Range masters stationary and moving balloon cars
During the tests with the stationary ADAC Target the RT3002 and the RT-Range Hunter is installed in the vehicle. The stationary balloon car is defined as a fixed point in the RT-Range software. The RT-Range software can pick up the location of the RT and uses it for the fixed point (ADAC Target) location. Simply drive the RT-Range to the location where the fixed point needs to be set and create a new fixed point at this location.
When the vehicle cannot be driven to the exact fixed point location it is a simple process of getting the vehicle close, then entering some offsets from the vehicle to the measurement point. The software will use the heading, pitch and roll information from the RT to compute a precise latitude, longitude and altitude of the fixed point.
When the ADAC balloon Target is towed behind a real vehicle (on a track), another RT3002 and the RT-Range Target is installed in the car which tows the balloon. This means the Target vehicle is the real car but the measurement position is 30m behind the real car, where the balloon is towed. Being able to define the measurement point up to 100m behind the car is an invaluable feature of the RT-Range and allows car manufacturers and other organisations to conduct tests with towed balloon cars.
With the RT-Range system, ADAC was able to measure the relative speed between the vehicle and the balloon car as well as the position of the car compared to the balloon Target with highest accuracy. The RT-Range software also outputs useful measurements like time-to-collision, longitudinal range, lateral range and more.
And the RT-Range ADAS test system can do even more. The RT-Range is the most comprehensive test tool for the development of ADAS technology, giving more vehicle-to-vehicle measurements and more lane positioning measurements than any other system. It is ideal for benchmarking and verifying many active safety features in vehicles. The RT-Range works with up to four Targets, which can be other vehicles, pedestrians, balloon cars or fixed points, thus ensuring complicated traffic scenarios can be replicated on the test track.
Being able to quickly transfer test equipment from one vehicle to another is crucial when benchmarking 10 different vehicles. All OxTS measurement systems are quick to install and can be transferred between vehicles within minutes using the RT-Strut mounting pole.
And the winner is….
All advanced emergency brake systems tested by ADAC are capable of significantly reducing the severity of rear-end collisions. The BMW 7-series was the overall winner scoring the highest number of points for its advanced emergency braking system closely followed by the Mercedes C-Class and the Volvo V40.
Images: Courtesy of ADAC www.adac.de