Road transport safety is a top priority across the board—for public authorities, vehicle manufacturers, and citizen drivers alike. In many cases, improving safety means reducing the impact of human error.
Advanced technologies such as Autonomous Emergency Braking (AEB) systems can now take control of a vehicle in situations where a collision, with another vehicle, a roadside object, or a pedestrian, is likely. But a real concern, especially with autonomous systems, is whether the systems themselves are actually safe.
Needless to say, full testing is crucial before any new and advanced technology is ever deployed in a real vehicle on a real road. And that’s where 4activeSystems GmbH comes in.
The Traboch, Austria–based company’s General Manager Martin Fritz says, “We work in the field of active vehicle safety with our main focus on facility technologies and dummies, which we use to test driver assistant systems, such as AEB. Because we use GNSS instead of light barriers for controlling our system, we have improved performance in crash-point precision. Controlled scenarios we could never have imagined are possible now with GNSS in our system.”
The Test Subject
An AEB system comprises a set of sensors to monitor the environment surrounding a vehicle, to the front, side, and rear. Inside the vehicle, sophisticated software works to recognize situations where relative speed and distance between the critical objects and a moving vehicle suggest a collision may be imminent.
“Once the sensor detects an object,” Fritz explains, “algorithms may classify it as relevant, for example, as a pedestrian or bicyclist. After positive classification of a particular object, the system starts tracking it, developing a prognosis of its path.” If this path intersects with the vehicle trajectory, emergency braking can be automatically applied, once the driver is warned, to avoid the collision or at least to minimize the effect.
“The main actor in our test systems is a road-crossing, human-like dummy, controlled by a special drive unit,” Fritz says. “Essentially, the dummy is meant to get in the way of an oncoming vehicle, with a projected impact to occur with a specific part of the front of the vehicle.”
4activeSystems dummies—which, by the way, are sometimes hit by a vehicle during testing—simulate adult and child pedestrians and cyclists. However, they are recognized as real humans by the vehicle’s mono and stereo visual camera systems, as well as radar and infrared systems. In tests, the dummies elicit a homogeneous distribution of the Radar Cross Section (RCS)—a measure of the detectability of an object by radar—with the RCS values remaining relatively constant from different views. For infrared sensors, the dummy is 50% reflective in the spectrum between 850 and 950 nanometres.
Conventional AEB testing systems tend to use a scheme that positions several pairs of light barriers across the path of a test vehicle. As the vehicle moves forward, its distance from the end target, the dummy’s path, can be tracked. Once the vehicle is at the right distance, the dummy can be made to move out into the vehicle’s path, allowing observers to record and assess how the vehicle’s AEB system reacts.
“With light barriers, we can even adjust the speed of the dummy based on variations in the speed of the vehicle,” says Fritz, “by recording the delay as the vehicle crosses the barriers. Of course, the accuracy of our corrections depends on the number of barriers and the distance between them.”
Increasing the number of light barriers provides greater accuracy for such systems, but more barriers also mean greater expense, in terms of materiel and set-up time. “What’s more,” says Fritz, “with a light barrier system, adjusting the path of the dummy in relation to possible sideways displacement of the nearing vehicle is impossible.”
So, the main benefit of using GNSS instead of the light barriers is that the team can determine the precise distance and the sideways displacement of the approaching vehicle, continuously, in real time.
“We have the ability to trigger the dummy movement in exact relation to vehicle speed, vehicle distance, and vehicle side displacement,” Fritz says. With continuous GNSS data from the vehicle, we can control the dummy movement for an optimal and precise crash point with only a few centimetres deviation.”
The company’s mobile test rig 4activeSB is small in size and easily transported by a passenger vehicle, Fritz says. Two people can set it up in just about half an hour with no need to fix it to the ground. The system is battery powered, with a minimum operating time of 10 hours at low temperatures.
The GNSS arrangement consists of a moving base station mounted on the vehicle roof and a stationary rover at the system drive unit. Each has a NovAtel Smart6–L antenna, generating ready-to-use, precise, Real Time Kinematic (RTK) differential data that includes distance and angle between the two antennas, which communicate through a wireless serial data link.
“Our system gives us high positioning accuracy,” Fritz says. “It is fast and easy to use, it does not interfere in any way with on-vehicle AEB sensors, and it is waterproof and wind-stable.”
A Good Match
Fritz says the NovAtel antennas along with special firmware installed in the receivers, fit 4actionSystems’ needs like a glove.
“It’s like tailor-made,” he says. “We get high-precision relative positioning data at an affordable price compared to a usual base-rover configuration. Another benefit is that the user does not need to intervene once the vehicle starts moving.”
4activeSystem got its GNSS antennas from PPM GmbH, one of NovAtel’s European distributors. “From the outset, we told PPM what we needed in terms of relative positioning. At that time we were not yet familiar with the special firmware solution. The very first recommendation from PPM was essentially the system you see today. So, it was a short track from our first inquiry with PPM to fitting out the system with NovAtel equipment,” Fritz says.
After one year of cooperation and taking numerous systems to market, 4activeSystems undertook a small upgrade that improved data-reception performance, based on an evaluation of customer feedback. The system is also now Galileo-ready.
Today, 4activeSystem markets a range of GNSS-equipped testing systems, with slightly different features based on specific user needs. The 4activeLD system, for example, is designed specifically for testing interurban AEB according to the European New Car Assessment Program (Euro NCAP) specification, with predefined and precisely controlled dummy movements.
And, we might add, the company has marketed its systems quite successfully.
“We are working worldwide with all relevant driver assistance systems and pedestrian and bicyclist detection systems,” says Fritz. “Our clients include car manufacturers Audi, BMW, Daimler, GM, Ford, Volkswagen, and others, as well as suppliers such as Bosch, Continental, Denso, and TRW.
And 4activeSystems provides the equipment for Euro NCAP’s testing and evaluation regime for AEB-VRU (Autonomous Emergency Braking—Vulnerable Road Users). Fritz says “All seven Euro NCAP labs are now using our test equipment and dummies. These include ADAC, BASt, CSI, TNO and others.”
Most experts agree that new active vehicle safety systems such as AEB are effective at mitigating the effects of road collisions and ultimately saving lives. With improved and more affordable testing regimes like those being delivered by 4activeSystems that employ GNSS technology, we can expect to see more of these high-tech safety technologies on our roads and highways soon.