RESEARCH ANALYSIS: A review of tomorrow's driver assistance systems

Research has shown that driver error is one of the most common causes of traffic accidents. Driver assistance technologies can therefore provide a helping hand in times of trouble. Matthew Beecham reports on how this form of back seat driving performs a vital role in tomorrow's car.

Driver assistance systems - either on the road or still on the drawing board - divide into three camps:

    * Collision-warning systems - this is the original term for forward and side radar systems which simply alert the driver but do not control engine speed.
    * Collision-mitigation systems - in addition to sending out a warning to the driver -- either through audio, visual or vibrating the steering wheel -- these systems aim to assess the danger ahead and trigger various active safety features, such as pretensioning the seatbelts.
    * Collision-avoidance systems - using these systems mean that some degree of control is taken over from the driver if he or she doesn't react in time to avoid a crash.

Bosch’s parking assistance system used on the Citroën C4 Picasso. The Citroën C4 Picasso is the world’s first car to feature integrated parking space management, supplied by Bosch.

In defining driver assistance technologies, an auto executive told us: "We prefer to talk about collision mitigation rather than collision avoidance. That's because we can't see accident-free traffic happening for some time. In the meantime we will look for everything to help to avoid accidents but we know that we will not be 100% successful. So what we see in the near future is driver assistance, i.e. systems that support the driver in his or her tasks, relieving them of the mundane activities.

"It also helps in critical driving situations. When we started developing driver assistance systems, they were perceived as comfort and convenience systems. But now it has changed a little bit in the direction of safety. That means that the driver feels that he or she has a safety technology when buying a driver assistance system. And we see that trend increasing in the future."

The most common suite of driver assistance technologies available today includes adaptive cruise control (ACC), lane change assistance, and parking assistance systems. The continuous development of these systems is accompanied by the European Union's eSafety action programme for road safety, which aims to halve the number of road fatalities by 2010. Hella remains supportive of this EU programme.

The German lighting and electronics specialist is busy engineering driver assistance systems so that it can move rapidly down from the initial high-line applications through to smaller and less expensive cars. Hella's driver assistance system combines applications including an ultrasonic-based parallel parking system, rear-end collision warning, lane-departure warning, rearview cameras and sensors with advanced image-processing software.

"In October 2006, we announced that adaptive cruise control would be in the Chrysler LX 300 both in Europe and the US," said Winfried Menge, marketing director of the electronics division at Hella. "Our ACC is based on infrared technology [LIDAR] which is considered more and more as an alternative because the performance between LIDAR and 77GHz radar is similar. Yet there is still a big cost difference between the two technologies. Although the 77GHz system became cheaper, there is still a big cost gap between LIDAR and 77GHz. In fact, I would say that LIDAR is about 40% cheaper than 77GHz. That is based on a standard sensor. If you then include other functionalities which are mostly just software add-ons, then of course the relationship starts to decrease."

In developing these driver assistance technologies, there is some debate among suppliers and automakers on the most suitable way to warn the driver of imminent dangers on the road. "It is really a hurdle in terms of how to bring all of this information to the driver," said Rolf Adomat, manager of development of driver assistance systems, Continental Automotive Systems.

"For lane departure warning systems, people have a bleep when you are crossing the line. A better solution is to vibrate the driver's seat and influence the steering. Also, that type of human machine interface [HMI] warning system will not interfere with the other occupants. So I feel that we need to study intelligent HMI in greater depth."

Menge agrees that determining the best way to alert the driver of imminent dangers entirely depends on the situation. He told us: "The most important thing is that the driver recognises the message without distraction. We have a very good solution in the Audi Q7 which has a lane change assistance system with an LED fitted in the A pillar. It gives the driver very intuitive information.

"The driver is supposed to look into the rearview mirrors anyway just before changing lanes. This is a very calm way in which to deliver information to the driver with a clear warning message. The vibrating steering wheel is good for everything that has to do with the lanes. If you do not have the lane departure warning system and you were to leave your lane, for instance on a lonely countryside route, then you would recognise, with the vibrating seating or steering wheel, that you were starting to go off-road.

"Again, the feedback is very intuitive. On the other hand, it is not a good idea to deliver just audible warnings because these may not be heard due to people talking in the car, or wind noise from an open window. So flashing something or giving the driver a direct signal through vibrating the steering wheel or seat is a very good compilation of the human machine interface."

Continental Automotive Systems has also developed a road sign recognition system. Adomat added: "We already have it running in the car. It is not a standard feature but an optional piece of equipment. It is very difficult to predict the market take-rates. It very much depends on marketing. When there is not very good marketing then it is very difficult to have very high volumes. That is what we have learned from using ACC. So I think that the market has learnt a lot and now we need to use that experience to get more awareness of these technologies such as sign recognition.

"The other thing is that teaching and training the dealerships and end-customer is very important. From the end-customer's point of view, while ABS and ESP are relatively easy to understand, technologies such as ACC with stop-and-go functionality, lane departure warning systems and so on take longer to understand. So yes, it is a hard sell. And we see it in the volume figures of the market in general in that the early expectations of these technologies were not reached. It is a shame because we have a wonderful technology which supports the European Union's e-Safety initiative to cut fatalities by half by 2010 but few people are actually aware of it."

Hella has also developed a traffic sign recognition system. "Company car drivers would welcome this technology," added Menge. "By merging the adaptive cruise control with a traffic sign recognition system means that you can alert the driver and slow the car down in speed-restricted areas."

In addition to Hella and Continental Automotive Systems, there are other major manufacturers investing huge sums into pushing back the boundaries of driver assistance.  They include Bosch, Delphi, Denso, TRW, Siemens VDO and many smaller specialist engineering companies.

In fact, for many years Bosch has been one of the frontrunners in pursuing the aim of reducing the frequency and severity of road traffic accidents by developing active and passive driving assistance systems. According to Bosch, driver assistance systems aim to make the vehicle capable of perceiving its surroundings, interpreting them, identifying critical situations, and assisting the driver in performing driving manoeuvres. The object is, at best, to prevent accidents completely and, at worst, to minimise the consequences of an accident for those concerned.

"Our approach involves the development of a so-called predictive system," said Professor Peter Knoll, president and CEO of Bosch's Counselling Service for Driver Assistance and Driver Information.

"That means we have sensors which scan the car's environment, detect obstacles, measure velocity and relative speed, calculate dangerous situations and then warn the driver in the first instance and then interact with the vehicle in the second. It is a stepwise approach using high-performance sensors. Our approach therefore focuses on ultrasonic for very low speed, radar for high speed and range, video for medium range and night vision. The enabling technologies are, of course, computers. We need high calculating power, software and algorithms to calculate all of these functions."

Siemens VDO Automotive has also developed a parking assistance system, dubbed Park Mate. It forms one part of a network of driver assistance systems that the German supplier is currently developing. The technology automatically measures the row of parked cars and alerts the driver when its sensors detect an adequate space for parking. It works using electronics is a similar fashion to rival technologies.

We can expect to see more of these so-called "intelligent" parking assistance systems this year. These systems will make parking easier by giving clear recommendations, allowing the driver to manoeuvre easily into a parking space. Following this, a more advanced version will employ an electronically controlled power steering system that converts the computed steering motions directly into the movements the steering wheel has to take; the driver will only have to apply the accelerator and brake.

For example, Bosch will soon release more functional enhancements to its ultrasound-based parking assistant. At the beginning of 2008, a system will enter production that will both measure the length of a space and suggest the best way to steer and manoeuvre into the space. A further development level in the same year will make it possible to directly control electrically supported steering - the driver will only need to operate the accelerator pedal and brake, while the parking assistant will take care of the steering. Such systems - from another supplier - are already in use on the Lexus LS460 and optional on the Toyota Prius.

Japan's Denso Corp is also busy developing its own solutions. "For complicated driver assistance systems involving traffic conditions, drivers, and vehicle movement, we believe that recognition technologies are the most important key technologies to accurately operate the system," said Akira Isogai, manager at Denso Corp's technology planning department. "Thus, we have been focusing on sensing technologies that can recognise vehicle-surrounding and driver conditions and communication technologies used to coordinate with other vehicles and infrastructures."

As far as Denso's stage of development with regard to its driver assistance system, the company is making use of some clever sensors.

Isogai added: "Conventionally, sensors such as LIDAR, millimetre-wave radar and vision sensors were used in driver assistance systems independently to recognise vehicle-surrounding conditions. Now, we are working on combining several different sensors, so that we can achieve more accurate recognition.

"In addition, we believe that car navigation systems will play an important role in detecting vehicle-surrounding conditions. We are working on developing advanced safety systems that incorporate car navigation functions. For technologies that recognise driver conditions, we are working on developing technologies that can identify the driver's face, monitor optical conditions such as blinks, and monitor the heart through an electrocardiogram. To achieve communication with other vehicles and infrastructures, we are participating in national projects in and outside Japan to develop and standardise communication technologies. In the US, we provide in-vehicle communication devices for a national project. We will work to diffuse these technologies in the market by developing new technologies and providing them at lower costs."

While all of these driver assistance systems - from collision warning through avoidance - are feasible either now or at some point through this decade, there are significant problems in software control, not least in how to make the various systems work together to form a true protection zone around the vehicle and then developing algorithms to determine if or when the system should intervene with the driving process. How much further can this technology go?
"We have already introduced parking assistance, adaptive cruise control, night vision systems, and predictive safety systems," concludes Knoll.  "In addition, we have developed systems which are ready to be introduced, which warn the driver of an unintended lane change or other road users in the car's blind spot. To get intelligent and helpful functions, we always have to take the driver's intention into account. Therefore we designed algorithms which aim to detect the driver's will.

"For instance, the driver only wants to be warned when leaving his track if he does intend to change his lane. Only in case of sleepiness or inattentiveness a warning is helpful for the driver.  We also have a traffic sign recognition system which is in an advanced development state. This system reads traffic signs and warns the driver if he is driving too fast. It now depends on the will of the OEMs whether or not they want to introduce such a system."