Tue11252014

On The Road

Manufacturers make strides in safety systems

In light of the recent epidemic of cars crashing into local landmarks, we’ve been thinking about the safety systems being incorporated in the design of new cars – like the Audi A8 (see accompanying review).

Although drivers may not be getting any better, the cars themselves are doing a much better job of protecting us.

The cars designed today include an array of safety systems, which we can divide into three categories: passive systems, active systems and elective systems.

 

Passive systems

Passive safety systems are those that protect the occupants in the event of a crash. In the 1950s, Mercedes-Benz was the first manufacturer to introduce the concept of a unit-body chassis designed so that portions of the body structure would collapse on impact, absorbing the energy of the crash, while other parts of the structure would remain intact, protecting the area surrounding the occupants.

At approximately the same time, Volvo pioneered the concept of three-point seatbelts that keep occupants from moving around within the cabin and protect them from the secondary impact of hitting parts of the interior.

These two systems have improved, and are now standard on nearly all automobiles. More recently, they have been supplemented by air bags designed to absorb secondary impacts within the vehicle cabin.

As a consequence of these three systems, far fewer accidents today result in occupant fatalities than was the case even two decades ago.

Active systems

Active safety systems help prevent collisions by allowing the driver to maintain control of the vehicle. Most of these systems are familiar enough to be represented by an alphabet soup of acronyms.

ABS, anti-lock braking system, was the first such system. Now standard on nearly all automobiles, this system pulses the brakes when they are activated in a panic-stop situation, avoiding skids and allowing the driver to maintain control. The only caution is that the driver must push the brake pedal aggressively and keep the pedal down, despite the pulsing sensation produced, then continue to steer the car to avoid collision.

If you’ve never experienced that pulsing situation, find a deserted street or road, and from any reasonable speed – no need to go fast – jam the brake pedal down. Then you’ll know what to expect if you should need to stop the car abruptly.

TCS, traction control system, uses sensors that measure wheel rotation. If a wheel starts to spin, TCS uses the ABS capability to activate the brakes on just one wheel at a time to allow the driver to maintain control.

ESP or ESC, electronic stability program or control, is becoming a standard feature on more and more cars. This system, essentially a more sophisticated version of traction control, uses sensors that detect the car’s sideways or rotational motion and computer programs that analyze that motion and compare it to the driver’s steering input.

If the computer determines that the car is moving in a direction that was not intended, it uses the ABS and throttle control to reduce the speed and selectively slow one or more of the wheels to bring the car back into a straight line.

If you’ve ever gone into a tight corner too fast and experienced the car slow down and move sideways, you’ve felt your ESC system prevent you from skidding off the road.

 

Elective or warning systems

The new marketing hype concentrates on the third category of safety systems these days. New enough that the term for the category isn’t even standardized yet, these systems essentially help drivers avoid accidents by alerting them to potential danger.

Among the more obvious ones are backup and parking sensors that beep when the car is too close to an object, backup cameras that provide a better view of the area behind the car than available from the rearview mirror, and tire-pressure monitoring systems – mandatory on new cars – to warn the driver that a tire has too little air for safe maneuvering.

 

The next wave of safety

Beyond that, we’re seeing sophisticated innovations appear on the more expensive cars, usually as options, as the companies work to absorb development costs. As development reduces the price of these systems, we can expect to see them as standard or at least as available options on the lower-priced cars.

One interesting system standard on all new Mercedes-Benz cars is Attention Assist, symbolized by the icon of a steaming cup of coffee on the instrument cluster. Mercedes-Benz engineers found that as drivers become drowsy, their steering input changes, generally before they are even aware of being sleepy. Instead of making constant small corrections to the steering wheel, the driver stops moving the wheel, then makes abrupt, larger corrections. By monitoring the steering inputs, the vehicle’s computer can sense when the driver is getting sleepy and flash a warning on the gauge cluster that it’s time to take a break.

Radar cameras are common on many new automobiles, positioned so that they can warn the driver if there is a vehicle in the blind spot beside and behind the vehicle, and beep a loud warning if the driver starts to move into the occupied lane.

Braking safety systems are also getting attention. Several manufacturers now incorporate radar into their cruise control systems to slow the vehicle as necessary to automatically maintain a safe distance from the car ahead.

Several manufacturers have introduced enhancements to this system that operate even when cruise control is not active. If the car is approaching a vehicle at a rate that could produce a collision, the system flashes and sounds an alert, pre-tensions the seat belts and increases the pressure in the brake system so that if an abrupt stop is necessary, braking action and seat-belt protection will be quicker.

Some of these systems are even capable of slowing the vehicle and, if necessary, bringing it to a complete stop before impact. Volvo is introducing a system that operates at the low speeds at which most rear-end accidents occur. Similar systems might prevent accidents such as those we’ve seen in the village recently.

Audi, Mercedes-Benz and BMW offer night-vision cameras – once limited to combat systems – as options on high-end cars. These systems produce an image of the road, beyond headlight illumination, on a screen in front of the driver. Some use pattern recognition to identify pedestrians in the vehicle’s path beyond the headlights, sounding a warning, highlighting the image of the person ahead and slowing the car down, if necessary.

Other systems use cameras and pattern recognition systems developed recently in research programs, including Stanford University’s autonomous vehicle research program, to warn the driver when the vehicle is drifting out of its lane.

Mercedes-Benz introduced a system in its European cars that reads the speed-limit signs and flashes a warning on the dashboard if the driver exceeds the speed limit.

It’s hard to believe that all of these high-tech safety systems are standard or being introduced as options on automobiles in the marketplace. Now, if we could just manage to do our part as drivers and parents to practice safe driving methods, avoid the use of cell phones and make sure our children get good driver training, the combined safety measures could drastically reduce the number and severity of auto accidents.

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