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City safety systems: emergency braking assistants being tested

Achim Hartmann
City safety systems
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T he pedestrian with shoes is almost 1.90 meters tall, wears a black jacket with blue trousers as standard, and shuffles across the asphalt at around 1.4 meters per second. Thanks to its curves and contrasts, it is easy to see for mono and stereo cameras, its RCS (radio cross section, radar echo) corresponds to that of a normal person, and in infrared it reflects back in the wavelength range between 850 and 950 nanometers.

Insightful dummy experiments

Boom, the test car caught the stroller with the area between the right headlight and the radiator grille and pushes him a little rough. That is not a problem, because the pedestrian is made of styrofoam, magnets hold his shoes on an aluminum plate that is pulled across the street by two toothed belts. It is part of the so-called 4a platform, a device for testing pedestrian protection systems.

The Euro-NCAP tests are run with the 4a platform, and the industry also uses the device for internal tests. We selected six vehicles with pedestrian detection and emergency braking to test how reliably the systems warn of an impending collision or prevent an accident by braking in good time. Even if real life is much more complex than can be reproduced with dummy experiments, the test still provides information about how effective and future-oriented the systems are. Autonomous driving, for example, is unthinkable without reliable pedestrian protection.

Inexpensive safety systems under 1,000 euros

Complex safety systems have also been around for a long time no longer a privilege of expensive luxury cars, they are even available for small cars. For example, there is already a VW Up a system that costs only 605 euros extra and detects the area in front of the car with a laser sensor up to 30 km /h. Incidentally, a maximum of 30 km /h because the sensor can only see ten meters. If there is no reaction from the driver, the VW applies the brakes and, if necessary, hits the iron.

The Safety Shield in the Nissan Qashqai should warn for this. It costs 700 euros extra, but is only available in the top equipment called Tekna, which is why a Qashqai with the security system at least 28,500 euroscosts. Behind it is a 360-degree camera system that is designed to detect obstacles moving around the car and warn of an impending collision. Allegedly, this even works when reversing and crossing pedestrians.

However, it can only emergency brakes if there is an impending collision with a car in front, which is why the Nissan only completed the pedestrian test for the sake of completeness. The Driving Assistant package in the Mini is a bigger caliber: for 990 euros it offers pedestrian detection and emergency braking functions, for example, adaptive cruise control, traffic sign recognition and a high beam assistant.

Subaru Outback from 40,000 euros with Eyesight system

Actually logical, because all these assistants use the same sensors. In addition, the basic version of the Driving Assist package is available from 16,800 euros. The Eyesight is standard on the Subaru Outback, but only in the more expensive equipment versions and only with the continuously variable transmission called Lineartronic, which not everyone likes. This means that there is no Eyesight in any outback that costs less than 40,000 euros.

The system works with a stereo camera, the two lenses of which are aimed at the street with great parallax on the left and right of the inside mirror. In geometry, this is understood to be the angle between two straight lines that come from different locations to one point. For stereo cameras, this means, among other things: the greater the parallax, the more precise the spatial image of the camera. Enough with textbook physics.

Now to the safety system in the Volvo V60. In addition to Mercedes, Volvo is the pioneer of passive and active safety technology in automobiles, and the safety package in the current V60 is correspondingly extensive. City safety technology is always on board as standard, for an additional 2,150 euros there is the driver assistance package Pro, which also includes active cruise control, a traffic jam assistant, the Cross Traffic Alert for reversing and other useful features. It is of course available for the entire V60 range.

Everything on board in the Mercedes

It looks similar at Mercedes, after all, the development department is based in Sindelfingen on Béla-Barényi-Straße, so the name of the safety pioneer is almost obliged to make special efforts. The basic pre-safe brake package costs 393 euros extra, but is automatically included when ordering the driver assistance package plus for 2,499 euros.

The package then offers almost everything that Mercedes has in terms of safety technology, from the Distronic adaptive cruise control to the Pre-Safe Plus, which is designed to detect an impending rear-end collision and initiate appropriate measures. So the dummy with the black jacket is pulled over the road again at the end.The Subaru rushes up at exactly 50 km /h, the test driver at the steering wheel does not react, but the Outback brakes independently - and stands.

The dummy shuffles on, between the Subaru nose and dummy kneecap could still be Drive through VW Up . There isn't even a reading. This is because the Subaru is already at the light barrier, which measures the remaining speed two meters before the impact. The walker resigns. The table below shows how the systems performed overall.

Mercedes C-Class

Pre-Safe Brake (2,499 euros): A question of design

The system comes up with a surprise during the first attempts with the C-Class. The following applies to our special test set-up: only with a little practice is it possible to elicit good deceleration values ​​from the pre-safe brake. The solution to the riddle: Since Mercedes attaches great importance to security against false alarms, the computers in the vehicle assume that the driver will take over command even with the slightest steering or accelerator movements and remain inactive.

The aim of the developer: The system should not be annoying in everyday life with incorrect triggering. However, the automatic brake works very well and reliably when approaching a stationary obstacle. And the practical drive shows that false triggering of the system is rare.

Mini Cooper

Driving Assistant (990 euros): Good, inexpensive system, not quite perfect

At just under 1,000 euros, the system in the Mini is one of the cheapest in comparison. Nevertheless, at 30 and 50 km /h in most cases he manages to reduce the impact speed so that serious injuries would not occur in an emergency. At 30 km /h and 25 percent overlap, he was still 20.7 km /h about two meters before the impact, he made 23 km /h from 50 km /h.

These are decent values, because that This means that the Mini will come to a stop just in front of the dummy with ideal deceleration in the area of ​​gravitational acceleration. Because real life is different in Boxberg too, it is enough not to seriously injure the potential accident victim. All in all a very recommendable system.

Nissan Qashqai

Safety Shield (700 euros): Here the driver has to step into the iron

The 360-degree camera system only records moving targets, which is why the exercise of driving on the standing dummy is not necessary. When approaching the moving pedestrian, the Nissan warns in most cases, but the warning tones and messages in the display are so discreet that the benefit for pedestrian protection is questionable. After all, it works with theReverse, but it only indicates that there is an obstacle in the driving area behind the car.

Okay. After all, the Safety Shield is inexpensive at 700 euros and includes other functions such as collision warning, blind spot assistant and intelligent parking aid. However, it is only available in the most expensive configurations. But buying an expensive Tekna for this reason should hardly be worthwhile.

Subaru Outback

Eyesight (Standard from Comfort with Lineartronic): The eagle-eyed station wagon

Wow, that's impressive. As the only one in the test field, the Subaru always, but really always, comes to a stop very early. One almost thinks that someone is remotely steering the outback via satellite transmission and remote control. No matter which of the three exercises the Eyesight system has to pass, it remains sovereign.

In several cases the Subaru is already in front of the second light barrier, with which the remaining speed is measured two meters in front of the obstacle. Even involuntary steering wheel twitches or gas lifts by the test driver did not irritate the system. And the best thing about it: Even false positives remain extremely rare. Only once does the outback brake unnecessarily in everyday traffic, even though the car braking in front of it has already turned.

Volvo V60

Brake Assistant Pro (2,150 euros): Effective system with clear warning

The Volvo also has one or two inexplicable misfires and does not react to the approaching dummy in all attempts . These are exceptions, however, after a restart and a short calibration drive, the brake assistant is always active again and warns of the impending impact in good time.

Then it reduces the speed so significantly that it either (from 30 km /h) stands in front of the obstacle or (from 50 km /h) just nudges the styrofoam pedestrian. The system also works very reliably when approaching the stationary obstacle. The complete maturity and the level of development of the assistance systems at Volvo are also shown by the fact that unnecessary and annoying false warnings are very rare in everyday operation.

VW Up

Drive Pack Plus (605 euros): Inexpensive system with limited effect

One of the secrets of good assistance systems is the range of their sensors. Anyone who can see a long distance can react earlier than someone who can only see ten meters in front of their toes. Since the performance of the Drive Pack Plus improves significantly with decreasing speed, this is probably the reason for the limited effect of the system.

At 30 km /h the VW give the dummy a decent oneWhomp with it, on the best attempt it was still 23.6 km /h two meters before the impact, a mediocre value. However, the Drive Pack works very safely and reliably up to 25 km /h, so the dummy always remains upright, regardless of whether it is strolling past or standing. Very helpful for play streets etc.

This is how we tested

The pedestrian protection systems were tested with the 4a platform on the Bosch test site in Boxberg. A pedestrian dummy is pulled into the test vehicle's route at a defined speed on a walking board. The speed was chosen in such a way that the cars hit the dummy with 25 percent overlap, the speed of the test cars was the usual inner-city 30 and 50 km /h. The 25 percent test is a case of hardship because it leaves the protective system very little reaction time. However, it is part of the Euro NCAP program. In addition, driving at an accelerated walking pace (approx. 10-15 km /h) was tested on the standing dummy.

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