Safety: The active approach

Advanced electronics have allowed simple ABS to grow into truly active safety systems

Until quite recently, truck safety rested on passive systems, things like brakes that allowed drivers to stop as quickly as possible or cab structures that resist high impacts. But with the advent of reliable heavy-duty antilock braking systems (ABS) in the 1990s, the industry started down the road to a new safety era, one marked by systems that actively controlled vehicle performance to augment and even override the driver’s control.

The electronic controller developed for heavy-duty tractor and trailer ABS was the first important step in the evolution of active safety systems for trucks, according to Jon Morrison, president and general manager of Meritor Wabco. For the first time, a device could sense an impending lockup of any wheel and then modulate brake actuation to prevent a lockup, all with more speed and consistency than a driver, especially in emergency braking situations.

Building on that ability to monitor and control the brakes on individual wheels, electronic roll stability (ESC) for combination vehicles was the next important step in active safety in the early 2000s. That was followed toward the end of the decade by collision mitigation systems—controls that slow a truck without a driver’s input based on sensing the speed and activity of other vehicles.

Morrison describes this careful progression to ever more powerful systems as “building a pyramid of safety.” Today that pyramid has risen well above its ABS foundation to include a range of active systems that not only help trucks avoid accidents, but can also lessen the severity of accidents when they do happen as well as make driving a heavy truck easier and less stressful.

But the work on this particular pyramid is far from completed. We are about to see a next generation of active safety systems that promise significantly broader capabilities. More importantly, these systems will function in ways that not only help reduce accidents, but also help a driver focus on critical actions in emergency situations.

State of the art

Two companies, both with strong histories in heavy-truck braking, produce the most advanced active safety systems offered by truck manufacturers today. Meritor Wabco’s OnGuard and Bendix Commercial Vehicle Systems’ Wingman Advanced systems both provide adaptive cruise control that maintains a set following distance using throttle, engine brake and foundation brake activation to slow the truck automatically. They also provide audio and visual warnings to the driver when they detect a possible impact with a moving vehicle in front of the truck. And both currently automatically apply up to two-thirds of a truck’s braking capacity if they determine an impact is imminent with that forward vehicle, which can greatly reduce impact force.

Also part of the active safety offering from both is full stability control with active braking to prevent rollovers and maintain a driver’s ability to steer the truck in almost all conditions. This is offered as an integrated feature of Wingman and as a separate product called SmartTrac from Meritor Wabco.

While not active since they don’t take control of the truck—at least not yet—adjacent lane monitors that alert drivers to objects alongside their vehicles are another feature that can be added to these advanced safety systems.

Adaptive cruise/collision mitigation systems aren’t new. OnGuard, for example, has been on the market since 2007 and nearly 40,000 are in service now, according to Morrison. And they are quite effective. Con-way Freight has over 3,000 tractors equipped with the system, and recent data shows an 85% reduction in rear-end collisions and a 50% reduction in rollovers, he says.

What is new this year is better, more refined radar that provides the basic sensing for these systems. The Wingman Advanced radar can now look 500 ft. down the road and is sensitive enough to offer driver alerts on stationary objects, not just moving ones, according to T.J. Thomas, director of marketing and customer solutions for the Bendix Controls group. And while OnGuard doesn’t yet offer stationary object warning, the new radar technology it introduced in January has the high resolution needed to add that feature in the near future, as well as boosting its range by a third and enabling auto-adjustment to keep the system in optimal focus at all times, according to Morrison.

Current active safety systems undoubtedly offer great potential for advancing truck safety, but whenever you consider allowing something other than a driver to actually take control of a vehicle, especially in an emergency situation, you need to proceed carefully. You need a full understanding of when drivers need help, how to best give them that help, and how to most effectively provide that help within the truck’s performance characteristic. And that’s where truck makers are playing an increasingly important role.

Things like stability control, lane departure warning, and active cruise control “were once standalone, but now they’re parts of larger safety systems,” says Scott Newhouse, assistant chief engineer at Peterbilt Motors.

Not only do they need to be integrated into the truck’s basic control systems, “but as you add more of these systems to the truck, you want to make sure the driver environment is not overwhelming for the operator,” says Matt Cullum, Peterbilt’s engineering manager for electrical systems. “If you have an event, you want drivers focused on what they need to do to get through that event, not to be startled by a lot of warnings.”


Setting priorities

While some active safety systems like electronic stability control function without interacting with the driver, others like advanced cruise control or lane departure monitoring provide audio and visual alerts to the driver that change as the situation becomes more critical. When first introduced, these were bolt-on additions, explains Frank Bio, product manager-trucks at Volvo Trucks North America. “You have the advanced cruise control system with a separate box giving the driver information and then the lane departure system using another indicator,” he says. “It doesn’t matter what’s happening; both could be signaling alerts at the same time. The driver might be dealing with three different systems at the same time, when all you really want to tell him is to slow down.”

Volvo’s response has been a close integration of the Bendix systems with its instrument panel and controls. For example, Volvo Enhanced Cruise (VEC), which is its proprietary name for the Wingman Advanced system, is integrated with the VNL dash and “sets a hierarchy of warnings for the driver,” says Bio. “It has beeps that pick up speed as you get closer to the forward vehicle and a light bar surrounding the speedometer that goes from green when it’s just tracking a vehicle to orange and then red at the highest warning levels.”

This integrated approach even allows Volvo to place the warnings where they’ll be most easily understood when timing is critical. If the lane departure system senses a driver wandering to the right, for example, it produces a rumble-strip sound in the cab’s right-hand speaker. “The goal is to provide the driver with the correct warning at the correct time,” says Bio.

The other advantage of tighter integration comes from faster or fuller control over the electronics controlling the truck’s powertrain. Today most of the interaction is handled over the SAE standard J1939 data bus found on every heavy-duty truck, though that is likely to change in the near future for a variety of reasons.

Given all the electronic controls on a modern truck, “with alerts and control systems all talking, the 1939 data bus is getting pretty full,” says Thomas. “We’ve been asked by the OEMs to keep the amount of data [on the bus] to a minimum. We try to be minimalistic when talking to things like the transmission, engine or body controls, and keep detailed control for communications between our components. Messaging means a lot and takes a lot of effort, which is why we have to test in all conditions and why it takes so long to release products.”

With coming requirements for onboard diagnostics (OBD) for emissions systems, the 1939 bus is only going to be further capacity constrained and “that will probably push some change in the [communications] architecture,” says Morrison. Telematics are also increasing the use of that vehicle-generated data back in the office, creating further demand for greater detail from all vehicle systems, he points out.

With some truck manufacturers moving to greater use of proprietary engines, transmissions and other components, it seems likely that they will leverage their proprietary electronics to improve performance and expand features of active safety systems. Both Bendix and Meritor Wabco report that discussions about adapting their systems to such proprietary data busses are already under way.

“Active safety systems go hand-in-hand with powertrain integration,” says T.J. Reed, director of product strategy for Freightliner Trucks, which has just expanded its proprietary drivetrain by adding its D12 automated mechanical transmission to its Detroit engine family. Just like active safety systems, automating shifting along with careful design of displays and controls all contribute to keeping a driver focused on the job at hand, he says.


Deeper Integration

Faster, closer communications between all components and systems over a proprietary network could also lead to better performance on many fronts. “Take a predictive technology like 3D terrain mapping,” says Reed. “Letting that communicate with both the powertrain and the advanced cruise control will not only improve fuel economy, but make the radar and active braking more effective.”

In addition to performance, that kind of closer integration should also improve cost and reliability, Bio says. “As we see closer integration [with proprietary powertrains], expect to see additional features and better levels of performance.”

Like most things involving safety, the complex issue of data bus communications will probably evolve over time, but some near-term advances for active safety systems are a bit clearer.

One major advance close at hand is automatic braking triggered by stationary objects. As mentioned earlier, Bendix’s current generation will alert drivers if it detects a stationary object near its path of travel, and Meritor Wabco will add that feature soon. But differentiating between something that belongs alongside a road like a light post and something that does not like a refrigerator is a fairly complex task. Doing that with enough reliability and consistency to put a truck into full braking mode is exponentially more difficult.

Complementing the radar sensor with a video camera should solve that issue by greatly improving object detection. Bendix announced just last month that it is working with suppliers on a camera and video processors that will have the accuracy required to add automatic brake application for stationary objects.


Seeing the problem

Adding a camera will have other benefits as well, according to Morrison, such as the ability to video capture emergency events for both driver training and accident recreation. Video can also give you sign detection for better active braking and even in-cab navigation, and perhaps lead to more effective drowsy-driver detection, adds Reed.

Other new features for the next-generation Bendix system include better tracking of forward vehicles around curves, faster release of tracking when the forward vehicle moves out of the truck’s lane, and more customized braking actuation depending on whether the vehicle is being slowed in active cruise or is entering collision mitigation.

Meritor Wabco’s newest generation, introduced just this January, includes radar that sees around curves and a new display with more content and automatic dimming. Speaking in more general terms about future developments, Morrison expects more integration with OEM dash displays, combined radar/video sensors capable of bringing trucks automatically to a full stop, and perhaps high-force braking applied in crash situations.

Beyond that? Engineers at both the OEMs and their suppliers can envision active safety systems adding steering control to lane departure, drowsy driver monitoring and intervention, and systems to control driver use of personal communication devices. Vehicle-to-vehicle and vehicle-to-infrastructure communications are also already under development. These would bring both safety and productivity improvements by actively controlling vehicles moving down the road. And, of course, the ultimate in active safety—platooned convoys or self-driving trucks accelerating, turning and braking without any input from a driver—are also being tested.


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