Hella: making driving safer

Hella based in Lippstadt, Germany, but with facilities worldwide, is best known as a leader in the vehicle lighting market. However, it is also active in a number of electronics and body control segments and has recently made a significant move into driver assist systems. This presently includes such products as Lane Departure Warning, Lane Change Assistant and Top View Parking Assist, as well as advanced lighting products such as Intelligent Beam Pattern and LED headlamp systems.

At the heart of many of these systems is camera-based technology. Hella is now at the forefront of this technology following the takeover of Aglaia GmbH of Berlin, Germany in March 2006. This unit is set to be Hella’s new centre for image processing technology.

Increasing vehicle accidents require new technologies, such as driver assist. OEMs now build cars with advanced collision protection features, such as dynamic crumple zones, active seat belts and head restraints, and airbag systems, all of which are designed to protect the occupants of a vehicle in the event of an accident. However, the number of accidents and fatalities is still rising.

In 2005, 40,000 people were killed in road accidents in the EU, while another 1.2 million road users were injured. Scientific studies prove that many of the most serious road traffic accidents are caused by tiredness and micro-sleep. Indeed, according to a study in 2004 by the Traffic Institute of German Insurers, one-quarter of all fatal motorway traffic accidents were attributable to driver tiredness.

In response to these statistics, Hella is developing a range of sophisticated camera-based systems that are designed to assist in the prevention of accidents. One such development is the Driver Alertness System. Using a CMOS camera located in the steering wheel area and focussed on the face of the driver, the system can monitor facial and eye movements, calculating eyelid blink frequency and duration.

A normally alert person is likely to have a blink duration of about 0.5 seconds, but as they become tired and enter the micro-sleep phase then the eyelids will remain closed for a longer period of time. If, after a period of normal activity, the camera detects the eyelid remaining closed for one second or longer then a driver warning will be initiated. This can take various forms, such as and audible bleep warning, seat vibration, seat belt grabbers being activated or air conditioning system variation. The object is to get the driver back into a state of alertness gently and without startling him or her, which might in turn generate a potentially dangerous reflex reaction.

If the driver persists in driving following such warnings, it is possible that the system could be developed so that after the third recognition and warning of tiredness, the vehicle could be automatically slowed down and finally stopped in a safe location with the parking brake secured and the engine switched off. While this advanced technology is still very much in the early stages of development, Hella hopes to have the first generation of driver alertness detect and audible warning-only system in production by 2011.

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Looking further ahead, the system’s data rate and memory capability could be used to create a driver facial recognition system that could personalise the car’s settings, such as preset positions for seats, steering column, mirrors and air conditioning. This could be especially helpful in preventing car theft as the car would not start with an unrecognised person in the driving seat.

In other areas of driver assistance, Hella has four products already available:

• Lane Departure Warning (LDW)
• Lane Change Assistant (LCA), using 24 GHz radar sensor
• Adaptive Cruise Control (ACC), using infra red light detection and ranging sensor technology (LIDAR)
• Electronic Parking Assist (EPA), using advanced digital camera sensor technology.

In theory, motorways and dual carriageways should be the safest of all roads because traffic is going in the same direction, visibility is generally good, and the distances between the hard shoulder and central reservation are usually generous. Statistically, if one considers the accidents versus vehicle miles travelled on motorways then they are probably the safest roads.

However, due to the higher speeds and volume of traffic operating within close proximity, when a motorway accident occurs, it tends to be more serious than on an inner urban road. Travelling at 70 miles per hour, a vehicle is covering just over 100 feet per second. A tired driver can take one second to blink, which means he/she has just travelled 100 feet with their eyes closed. Changing lanes unintentionally to either side is clearly dangerous; an on-board system to alert the driver immediately can prevent an emerging hazard.

The Hella LDW system will detect that the vehicle is about to cross lane markings without the driver having given the signal to change lanes. In response to this, the system can alert the driver by several means, such as an audible warning, flashing light, seat vibration, seat belt tensioning or sat-nav audio voice warning. The exact choice of warning would be at the discretion of the OEM and could be varied depending on the potential danger of the manoeuvre.

If a driver decides to intentionally change lanes having checked centre mirror, appropriate door mirror, signalled accordingly and started the manoeuvre unaware of a vehicle in the blind spot area, then the resultant impact can have very serious consequences. If the target vehicle is say moving from the centre lane to the right lane at 70mph then the dynamics are similar to cornering with the nearside wheels becoming loaded whilst the off side wheels are unloaded. If the following vehicle is travelling at a higher overtaking speed and impacts the off-side rear corner of the manoeuvring vehicle, then this could result in the vehicle spinning out of control and rolling over.

The LCA system works on the basis of a 24 GHz radar sensor covering the areas on both sides of the car which are typically outside of the range of the centre and door mirrors. If the driver signals his/her intention to change lanes and there is an unseen vehicle in the blind spot area, a warning can be relayed to the driver by various means as described in the LDW system. This LCA system is now offered on the Porsche Cayenne and Volkswagen Touareg, and will be offered on a Japanese vehicle yet to be disclosed.

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It is possible that the system could be developed so that after the third recognition and warning of tiredness, the vehicle could be automatically slowed down and finally stopped in a safe location with the parking brake secured and the engine switched off

Adaptive Cruise Control

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Cruise control systems which allow the driver to select a steady state speed for cruising are now familiar features on vehicles both large and small. The benefits on long journeys particularly are welcomed by drivers as they reduce fatigue on motorways and can prevent exceeding the speed limits in built up areas.

Hella is developing an Adaptive Cruise Control (ACC) system which can further regulate vehicle speed in response to other vehicles in order to maintain a safe distance from them even when speeds vary. This system is based on infrared light detection and ranging sensor technology (LIDAR).

The driver can pre-select a cruise speed as normal, but as a preceding vehicle is detected, the road speed will be adjusted by the throttle in the first instance and by the brakes if required. Other parameters can be used, such as signals from the rain detecting wipers and outside temperature sensors, in order that increased stopping distances are calculated according to changing ambient weather conditions. The ACC system is already offered on the Chrysler 300C.

The latest rear view camera system includes an integrated CMOS image sensor. Having an aperture angle of 130 degrees the entire area behind the vehicle is clearly seen. When engaging reverse gear, a full colour image, compensating for external ambient light conditions, is displayed to the driver on a screen mounted on the dashboard. This allows the driver to see much more when reversing than could be seen through the rear view mirror or even directly through the rear window. This system is also available on the Chrysler 300C.
A future development of this technology is the Electronic Parking Assist, also referred to as Top View. Here, four such cameras are located around the car, front, sides and rear, each giving a 180 degree view. Using computer technology, these four wide angle images are transposed onto the view screen to represent a top view of the vehicle. The resultant image appears to show a bird’s eye view of the car with surrounding features, such as road/car park markings, nearby vehicles and pedestrians. This system enables the driver to position his/her vehicle accurately between lines when parking. It also allows the driver to manoeuvre safely when reversing out of a parking space between parked vehicles.

Further developments of this feature could include fully automated parking effected by drive by wire steering systems. Expect to see Top View from 2010 onwards.

Clearly, Hella is becoming much more than just a supplier of headlights and rear lights to OEMs; it is now entering into the areas of serious innovation for the camera-based driver assistant features. With contstantly increasing traffic speeds and vehicle populations, plus the burgeoning pressures of our daily lives, vehicle accident rates are likely to rise. Hella’s new technologies will hopefully help to reduce the number of vehicle accidents in Europe.

The intelligent lighting, rear camera and lane change assistant are now available for 2007 on some new cars. Hella hopes to see even more advanced features in production by 2011 to 2015. With these will come motoring which will be more comfortable, more convenient and above all a lot safer.
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