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Gary Anderson

We don’t know whether a car that can truly drive itself will ever be part of our future; what we do know is that the pursuit of the goal by Mercedes-Benz is already providing significant benefits in driver convenience and occupant safety.

Modern Technology
 
Mercedes-Benz Intelligent Drive
by Gary Anderson

 
Continuously pursuing the overarching goal of driver and passenger safety, Mercedes-Benz Cars has moved from the mandate of protecting occupants in a collision to the challenge of preventing a collision. Current research draws from the growing field of autonomous-vehicle technology to find ways that automobile systems can sense impending impacts and swiftly respond to prevent them. In the process, the company has proven that producing an automobile that can drive itself to a defined destination through real-world traffic conditions without human-driver intervention is not only achievable, but realistic.

What we don’t know is whether a car that can truly drive itself will ever be part of our future; what we do know is that the pursuit of the goal is already providing significant benefits in driver convenience and occupant safety.

The stuff of science fiction

Cars that can drive themselves have been the stuff of science-fiction stories and popular tech magazine scenarios of the future since the early part of the last century. Auto–nomous vehicles were the centerpieces of automotive manufacturers’ world’s fair exhibits as far back as the 1930s.

The emphasis in those scenarios was often on families taking their personal cars onto public freeways, engaging the electronic connection between the vehicle and control systems in the roadways, and then settling back to enjoy the journey, taking over control of the car only at the point of the exit. For better or worse, that’s the picture that springs to mind today when we’re told that autonomous vehicles will soon be available from dealers near us.

As recently as the 1980s, engineers and product planners assumed that cars that drove themselves would utilize sensors and transmitters built into new freeways, like invisible railroad tracks to which vehicles could be connected electronically, and follow those to the off-ramp nearest to the programmed destination in the car’s control system, at which time the driver would take over control again.
However, when this approach had been developed to the point of implementation, companies realized there wasn’t sufficient public support for funding the expensive technologies required in roadway infrastructure, so this development path was terminated.

In the meantime, as battlefield mobility and flexibility became increasingly important in modern warfare, the U.S. Defense Department launched a research program offering a combination of competitive prizes and basic research grants that challenged academic institutions and defense contractors to develop automobiles that could drive themselves over unfamiliar terrain to a specific location.

Though the first few years were comically unsuccessful – during the first trials in 2004, the most successful vehicle managed to go less than eight miles while most vehicles couldn’t find their way out of the parking area – each year has brought substantial progress. Now 10 years later, vehicles routinely complete increasingly difficult challenges, several private companies are demonstrating similar capabilities, and commentators are asking when autonomous vehicles will take over the chore of driving in civilian situations on public thoroughfares. But is this the wrong question to ask, and are there more important things to do with the technology that is being developed?

Sense, see, think and react

For a vehicle to drive itself, four families of technologies are needed. The vehicle must have sensors to be aware of its surrounding environment; actuators that control steering, acceleration, and braking; awareness of its geographic position relative to where it has been programmed to go; and most challenging, it must have software able to evaluate the surrounding environment, predict how that environment could change, and decide what actions to take in the anticipated situation while proceeding toward its goal.

Moreover, in a future scenario of autonomous cars on public streets and roads, another capability will be required: The vehicle will need to communicate with other vehicles nearby, relaying its position, direction and speed while assessing their positions and paths to determine its own actions along the chosen route.

Types of sensors and actuators

Although these required technologies still seem like the stuff of science fiction, more are already being installed in new cars than we might be aware. Under the general label “Intelligent Drive,” the 2014 Mercedes-Benz E- and S-Class have nearly all the sensors and actuators necessary to drive themselves – available as standard equipment or options – and most are available on the new C-Class as well.


As seen in the diagram (“Sensor Fusion”)  of S- and E-Class systems, sensors include radar, vision, and ultrasonic units that feed information to a computer processor.  A long-range radar beam mounted up front sweeps an 18-degree arc up to 650 feet ahead and can track cars and objects, while a short-range radar beam sweeps a 60-degree arc up to 200 feet ahead. A stereo camera mounted in the top center of the windshield emulates human vision, seeing 1,600 feet ahead and processing 3-D images across a 45-degree angle up to 160 feet ahead.

Toward the rear, three short-range radar sensors cover a 240-degree arc up to 100 feet away from the car while a long-distance radar sensor scans a 16-degree arc up to 260 feet to the rear. Objects from 8 inches to 15 feet away, in front and behind the car, are detected with ultrasonic sensors in the front and rear bumpers.

In addition, the system has motion sensors to track forward, reverse and lateral motion, and the vehicle’s tilt angle, while four cameras provide a 360-degree view of the area immediately surrounding the car.
Actuators controlled by the car’s Intelligent Drive computer can brake individual wheels using the ABS controllers, manage the accelerator to speed up and slow down, guide the car from the steering wheel, tighten seat belts, trigger the air bags, and activate alert signals on the dashboard and in the steering wheel.

Safety and convenience

Using various combinations of the sensors and actuators controlled by the computer processor, Intelligent Drive not only reacts to impending collisions to mitigate their effects, but also anticipates possible collisions and acts to prevent them. Also, the systems can work with the driver to reduce routine tedium, as well as mitigate or correct driver error that can lead to loss of vehicle control.

The specific systems applications are grouped into various capabilities. The Driver Assistance Package includes Distronic Plus with Steering Assist – an intelligent cruise control system; Active Lane Keeping Assist that also tracks oncoming traffic; Pre-Safe Plus and Pre-Safe Rear, Pre-Safe Brake with pedestrian recognition; and Brake Assist Plus (BAS) with cross-traffic assist. Other packages include Attention Assist, Collision Prevention Assist, Parking Assist Package with Parktronic Active Parking Assist and 360-degree surround camera, and the Lane Tracking Package that includes Blind Spot Assist and Lane Keeping Assist. In addition, the car is of course equipped with systems that Mercedes-Benz pioneered, and which are now standard on all new cars, including electronic stability control, antilock braking, and antislip regulation. 

Each of these systems is designed to prevent or mitigate a specific undesirable outcome: For example, Pre-Safe Brake with pedestrian recognition will warn the driver of a possible collision with a vehicle, object, or person ahead of the car, slowing the car or coming to a complete stop if necessary to avoid hitting something – or someone; Blind Spot Assist warns the driver if any vehicle is in one of the two blind spots, and will turn the steering wheel to prevent the driver from crossing into that car’s path.

With these complex combinations of systems, the new E- and S-Class cars are also capable of what Mercedes-Benz now refers to as “semi-autonomous driving.” As described in recent reviews of these new models, Distronic Plus with Steering Assist can dramatically reduce the tedium of driving in the slow-moving traffic of almost every rush-hour commute. Set the cruise control to the speed limit, and, as indicated by a green steering-wheel icon on the instrument panel, the vehicle will drive itself.

The accelerator and brakes keep the car moving at a safe speed up to the set speed limit while vision sensors and radar systems maintain a safe distance from the car ahead, track the second car ahead to ensure it isn’t stopping or slowing, and watch the lane markers and car ahead to steer the car on a course in its own lane.

Given current vehicle regulations, the driver is required to maintain attention, keeping a light touch on the steering wheel for all but the briefest intervals. Take both hands off the wheel for longer than it takes to open a bottle of water, and a warning signal is triggered, followed by the system’s shut down if the driver doesn’t take control. Nevertheless, the difference between keeping a casual eye over everything and actually making continuous minor adjustments to steering, accelerator, and brakes while watching traffic ahead and in the rear-view mirror is significant. Tedium and a potential lack of attention are dramatically reduced, making rush-hour driving a relatively pleasant break rather than stress-inducing torture.

We can also anticipate that when more and more vehicles get some or all of these capabilities – at least able to maintain safe speeds and distances in dense traffic – fuel efficiency, emissions, and accident rates will all improve.

One glimpse of the future

 Where are we going with these technologies? We’ve all read the articles and watched the programs and movies where vehicles drive themselves, finding their way to a designated destination while avoiding other vehicles, pedestrians and objects. In fact, Mercedes-Benz engineers recently successfully demonstrated an S500 sedan driving itself nearly 100 kilometers through city, village and rural traffic, tracing the same route driven 125 years ago by Bertha Benz when she proved that long-distance journeys were possible in a self-propelled vehicle.

The vehicle was equipped with the same sensors and actuators available on the 2014 S- and E-Class cars, with only one modification: the addition of two radar sensors mounted on the sides of the vehicle. This system is in marked contrast – in complexity and cost – to the Lidar (laser-based radar) system that Google and some universities now use on their prototypes. That Lidar system alone costs more than the full retail price of the S500 used by Mercedes-Benz.



Nevertheless, there were some significant challenges to overcome. The most difficult was the vehicle’s need to know its precise position, to within inches, at all times. This was accomplished by very carefully mapping the entire route within the system, down to the position of every bush, tree, building, intersection, light post, and stoplight. Next, the system was programmed to continuously compare what its sensors were observing to information uploaded in its global positioning system.

That would have been sufficient for the vehicle to make its way from the beginning of the route to the end – provided there were no other vehicles, bicycles, or pedestrians on the road. However, because the intent was to drive in real-world conditions, the system had to sense objects around it, determine what the object was and whether it might move, and then project its possible direction and speed relative to the S500. A truck moving ahead of the S500 might stay in its own lane or change lanes; a car approaching from the rear or a side road might stop or continue on an intersecting path; a person riding a bicycle could swerve or a pedestrian step out into traffic. Given the computer memory and processing capabilities now available, for the first time it was possible not only to program all this information and these algorithms into a computer, but mount the computer totally within the vehicle’s luggage compartment.

The goal of driving Bertha Benz’s route was successfully achieved in autumn 2013; a video of the accomplishment was shown at the Frankfurt Motor Show and was also then posted on the Internet.

Which road will we take?

Does this mean that Mercedes-Benz customers will one day be able to order a car capable of driving to a specified destination without human intervention? And if so, when will that be possible? The interesting thing about technology is that what can be achieved isn’t necessarily what will be achieved – or that the pursuit of a specific goal and its achievement is the point of the exercise.

Even if technologies improve to the point that vehicle systems can anticipate and respond to the myriad changing circumstances surrounding a car, there is still the problem of conditions along the route itself. In this case, the major limiting factor is the need to extensively map a specific route in advance, particularly given the infinite number of routes people might want to follow and the changes occurring daily along those routes. Beyond that, potentially long and problematic discussions revolving around questions of law and ethics arising from autonomous-vehicle responsibility have just begun.

While we may see driverless vehicles in controlled situations – Google has unveiled a prototype fleet of small people pods without driver controls that it will test as taxis for employees on its extended campus in Mountain View, California – the goal of autonomous vehicles driving through traffic from one point to another seems unattainable in the foreseeable future. 

However, developing new and improved algorithms that sense, process, and respond to changing circumstances around the automobile, as well as improving the reliability and reducing the expense of  the sensors and actuators, are certainly worthwhile and important goals in and of themselves. Moreover, pursuing these ends is a logical extension of current research and development programs that are designed to increase driving safety today and eventually render automotive collisions nearly impossible.

As these technical processes continue to develop, we can expect that significant progress will be made toward improving both efficiency and safety while reducing the required driver effort needed on typical commuting routes, as well as on long-distance journeys. Both of these lines of inquiry will continue to bear new fruit from year to year. Along the way, as the number of automobiles with semi-autonomous systems increases, driving conditions can be expected to improve — at least keeping pace or even gaining on growing traffic density – in urban centers and on major transportation routes around the globe. Our future may not be the world of “The Jetsons” or of “Knight Rider,” but it will be a safer and more pleasant one, nonetheless.