Way Forward Thinking
Driving a truck could get a lot easier and highways less dangerous if the driver-support and active safety technologies recently demonstrated by DaimlerChrysler’s Commercial Vehicles Division actually come to market. Many of them will, possibly all. The automatic Emergency Braking System, for instance, is optional on the Mercedes-Benz Actros tractor in Europe as of last month.
Accident-free driving is the company’s stated goal, and the spectre of ever growing traffic density, in Europe and North America alike, is a key part of the challenge, according to Andreas Renschler, the division’s chief and member of the DaimlerChrysler AG Board of Management.
“All in all, 70 to 80 percent of all present-day accidents can be avoided with the support systems offered by DaimlerChrysler,” Renschler told members of the international press at the company’s spectacular test track near Papenburg, Germany. “The most frequent accident types are rear-end collisions and vehicles swerving off the road,” he said.
Mercedes-Benz engineers Jürgen Trost and Ingo Scherhaufer have been studying truck accidents for years. Rear-end collisions account for 30 percent of accidents caused by trucks in Germany, they say, which makes them the single most common type. A crucial point here is that in 39 percent of these accidents, the trucks collide with the stopped vehicles without braking at all. What’s more, in another 20 percent the truck drivers don’t brake hard enough.
Scherhaufer and Trost began to develop a solution to rear-enders five years ago and were soon led to the idea of automatic emergency braking. The team has since completed countless runs on test tracks and driven many thousands of kilometers in actual traffic.
“The main problem isn’t automatically triggering an emergency stop,” explains Scherhaufer. “The real challenge is to prevent the system from braking when it’s not supposed to.”
The main ingredients used to keep that from happening are located behind the grille of the Actros and in the onboard electronics, the key component being a 77-GHz radar sensor that can detect a vehicle in front at a distance of up to 150 meters. Sophisticated software can identify which rear-end crash situations are so critical that only an emergency braking action can prevent the worst.
The foundation system, called Proximity Control, uses three radar beams to detect moving obstacles ahead of the truck and continuously calculates the difference in speed between the two vehicles. If an accident appears possible, the driver first receives a visual warning — a red triangle symbol lights up — followed by an audible warning. If the collision risk increases, partial braking (30 percent of braking power) is initiated to give the driver a further warning. If the driver doesn’t react, the system automatically applies full braking power. A fully automated panic stop, in other words.
This is an extended version of what we’ve been calling “active cruise control” on this side of the Atlantic. The Eaton Vorad radar system, for instance, can link obstacle detection with cruise control and the engine brake, and will drop engine speed automatically to maintain a pre-set following distance. In some setups it can order a downshift, but not braking action.
An enhanced version of the Mercedes-Benz system is already undergoing tests, and it will take into account the road surface’s coefficient of friction. A microphone in the wheel area records the tire noise and passes this information on to a computer that, in turn, determines the level of road grip. It can distinguish between five levels of friction coefficient, from dry surfaces to wet surfaces and from snow to black ice, and can calculate stopping distance accordingly.
Freightliner is also working on an advanced cruise control system called Predictive Cruise Control, or PCC. It reacts to information stored on a three-dimensional road map and uses this data to create a predictive driving strategy. It sets the speed selected by the driver, taking into account fuel consumption and driving time.
Thanks to its GPS receiver, PCC always knows the precise location of the truck. It accounts for the weight of the vehicle, detects dangerous downhill stretches at an early stage, and decelerates in good time before descents in order to save fuel. The system could be in production by the year 2010.
And how about an automated fifth wheel? With this Mercedes-Benz technology, the driver can stay in the cab while hitching and unhitching his trailer. A green indicator light in the cab tells him that the trailer has been hitched up successfully, while a red signal light beams in the event of error. The coupling is locked automatically, of course, and a single button push will unlock and release the fifth wheel.
The automatically extending and retracting trailer legs are also linked to the clutch. For safety reasons, they can only be lowered when the parking brake is applied. An additional mechanical lock prevents the trailer supports from being extended or retracted unintentionally.
Straight & Narrow
Already introduced as an option, the Lane Assistant is based on a camera system that detects the painted lines on the road and warns drivers if they’re veering outside their lane.
In an enhanced “active” version, not yet on the market, an electronic steering system intervenes, a technology called Road Departure Avoidance. If the truck starts to approach the side lane markings, the driver will feel a tugging on the steering wheel, allowing him to intuitively steer back into the lane before the system’s warning signal sounds. The torque felt on the steering wheel increases gradually as the truck gets closer to the edge of the lane.
After emitting a warning signal, the system guides the truck back into its lane by applying precise braking pressure at one of the truck wheels. The driver remains in ultimate control of the situation, since the system is deactivated automatically whenever he applies the brakes or turns the steering wheel.
See Around Corners
DaimlerChrysler’s Predictive Curve Assistant can help when a driver underestimates the radius of the turn at an offramp, doesn’t see all of a bend in the highway, or perhaps misjudges the dynamics of a laden trailer.
Using GPS navigation system data, the computer constructs a model of the road ahead of the truck. It then defines a safe maximum speed for the vehicle and continuously compares it with actual road speed, the shape of the bend, and the truck’s side tilt. If the actual speed of the vehicle starts to approach the critical level before a bend, the driver receives two warnings well in advance of the danger zone.
Go Ahead, Back Up
Precise maneuvering of a heavy truck when space is tight is an art in itself, requiring a great deal of feel and experience on the part of the driver. And repairing minor fender damage is one of the largest costs for truck fleets.
The DaimlerChrysler Truck Parking System with ultrasonic sensors at the front and rear makes maneuvering easier and helps prevent costly minor damage. Yellow warning lights progressively warn the driver of the distance to obstacles immediately in front of or behind the truck. If the obstacles get too close, red warning lights come on and a warning signal sounds to alert the driver of an imminent crunch. Ultrasonic sensors at the rear of a trailer can be installed to ensure smoother docking.
But it gets better. Designed to help drivers of tractor-trailer combinations, the Reversing Assistant consists of a camera at the rear of the trailer, which sends an image to a monitor in the driver’s cab. The driver guides the vehicle using a joystick mounted on the armrest of the driver’s seat rather than by turning the steering wheel. Commands are sent electronically to the steering system and the vehicle’s actual position is shown on the monitor. The driver can back around a 90-degree corner without looking at his mirrors and without touching the steering wheel. It’s certainly not on the market yet, but it could be coming.
So how much of this technology will we see in North America? Some of it will never cross the ocean, and for that matter some of it probably won’t make it to market in Europe either. But Renschler offers a clue as to DaimlerChrysler’s thinking when he describes one aspect of their increasingly common cross-brand engineering practices. What he calls the “common radar front end” refers to the radar technology that’s essential for the Emergency Braking and Proximity Control systems, and he says that as of 2007 it will be in use in all new truck concepts by Mercedes-Benz, Freightliner, and Mitsubishi Fuso.
The world grows smaller.
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