Smart braking on today's vehicles

Jan. 1, 2020
The radio is playing loud enough to drown out the kids in the back seat, who themselves are engrossed in the SpongeBob SquarePants video playing on the DVD. The phone is ringing, adding another demand to our attention as we try to stay focused on the
No matter the cause, when an accident is imminent and driver reaction is slow, smart braking systems can mean the difference between walking away and being carried away.

The radio is playing loud enough to drown out the kids in the back seat, who themselves are engrossed in the SpongeBob SquarePants video playing on the DVD. The phone is ringing, adding another demand to our attention as we try to stay focused on the primary task at hand: negotiating our way through rush hour traffic. Is it any wonder that accidents caused by distracted drivers are on the rise?

But new applications of current technologies might put an end to all that. Many manufacturers are offering new safety systems on their models, but becayse this is the European issue of Motor Age, we're going to focus on a company that has a long history of innovation: Mercedes-Benz.

Mercedes has contributed much to occupant safety technology. There are at least five widely used safety systems that can trace their roots directly to M-B’s safety research. The first is the energy-absorbing car body patented in 1951. The “crumple zone” design now is commonplace, providing a rigid passenger cell surrounded by energy absorbing front and rear body structures designed to deform at a pre-determined rate upon impact.

Driver fatigue and distraction is a leading cause of traffic accidents. ATTENTION ASSIST sounds an audible and visual warning when erratic steering inputs are detected.

Antilock brakes (ABS) was another Mercedes first, offered in 1984. And Mercedes actually coined the term Supplemental Restraint System, or SRS, to include the package system incorporating front air bags, knee bolsters and self-tensioning three-point seat belts. Last, but not least, the automaker has been a pioneer in traction control and electronic stability systems.

Now Mercedes-Benz has taken it one step further, introducing new production safety systems that protect the occupants from their own mistakes. And in so doing, protecting the rest of us from that distracted driver in the lane next to ours.

Time for a Rest? Distractions and fatigue both can cause a driver to swerve out of his lane. Whether it’s the shoulder or another occupied lane, the resulting impulse to over correct often results in a loss of control. M-B's ATTENTION ASSIST system uses a steering sensor and smart software to monitor more than 70 different parameters that establish a unique driving profile during the first 20 minutes of driving. The system continuously monitors steering inputs between speeds of 50 mph and 112 mph, looking for erratic corrections. When detected, the system sets off an audible warning and illuminates a “Time for a Rest?” along with a coffee cup icon in the instrument cluster.PAGE 2
Radar in the rear of the car is used to detect vehicles in the driver's blind spot. A red warning icon is visible in the matching side view mirror.

Maintaining Space
Driving in heavy traffic is a challenge on the best of days. Cars swerve into your lane or stop suddenly in front of you. And let's admit it, sometimes you're the one swerving or stopping! Mercedes addresses these safety situations with two new production systems: Active Lane Keeping Assist and Active Blind Spot Assist.

Active Lane Keeping Assist uses a camera mounted in the windshield and a software program that allows the control module to monitor the road in front of the driver. It can tell if the car begins to leave its lane, and if no turn signal has been selected, it simulates the rumble strip feeling we are all familiar with in the steering wheel through an electric motor. If the driver ignores the warning, this system uses the existing Electronic Stability Program (ESP) to activate the brakes as needed to gently draw the car back into its lane.

If the turn signal was active, Active Blind Spot Assist is in play. This system uses close range radar sensors to detect vehicles in the car’s blind spots and will turn on a red warning icon in the corresponding side view mirror. If ignored, the ESP system is used to again apply the brakes as needed to draw the car out of the danger zone.

If the driver ignores the red warning icon, the ESP system can activate the brakes as needed to protect the driver from himself.

As a side benefit to these DISTRONIC PLUS systems, a Park Assist system uses the six front and rear radar sensors to let the driver know if a parking space is big enough for his car. When the driver drops into reverse, guidance lines are superimposed over the images produced by the rear camera to make parking easier.

Keeping enough space in front of you to react in an emergency is handled by tapping into the adaptive cruise control system. Operating at nearly all speeds up to 125 mph, this system maintains a preset distance between you and the car in front of you. Short-range radar sweeps the first 33 yards in an 80-degree fan-shaped pattern. Longer range radar using a narrower beam allows the two to cover a range of over 160 yards. The system actually can brake the car to a full stop if needed to minimize impact in the event of an accident, if not preventing the accident completely in the first place.

Hitting the Pedal
Mercedes research revealed that most drivers do not apply full braking force when faced with an emergency. In the early 1990s, M-B developed Brake Assist to allow the computer to boost line pressure when a panic stop was triggered. Now there is Brake Assist Plus that factors in the radar inputs from the DISTRONIC PLUS, measuring the time and distance to impact, and adjusts brake line pressure accordingly. According to Mercedes research, this system has the capability of reducing rear end collisions by nearly 75 percent.

M-B’s Night Vision Assist helps to illuminate the road in front of the driver, using infrared technology. Combined with the adaptive lighting system and a video display, pedestrians can be detected nearly 500 feet away.

The newest addition is PRE-SAFE® brakes. This system monitors driving conditions, looking for an impending accident scenario. If an accident is imminent, three warning tones are sounded. About 1.6 seconds before a likely impact, partial braking is initiated automatically with or without driver input. Occupant safety systems are brought on line at the same time. Front seat belts are tightened, power seats are moved to positions affording the best protection for the passengers, and even the sunroof and/or side windows close automatically if a roll-over is likely or a side impact is detected.

If the driver fails to react sufficiently, the system applies full stopping power about 0.6 second before impact. Mercedes refers to this as an electronic crumple zone, reducing the severity of the impact as much as possible.

Are You Ready? It’s not just brake technology, it’s electronic brake technology, and it’s not all unique to Mercedes-Benz. Many domestic and Asian manufacturers offer similar systems on their models, with more to come.

We techs are going to have to learn more about how these computers do their thing in order to effectively troubleshoot and repair them. And keeping up with future issues of Motor Age or visiting our community site at is one way to do just that!

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