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Camera-controlled LED arrays pinpoint danger
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01/05/2007
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Infra-red night vision systems could be revolutionised by an LED headlight technology that illuminates dangers ahead with a narrow-beam spotlight, writes Roger Bishop. It provides a far more natural warning than head-up displays or LCD screens that require a driver to look away from the road.
The concept is one of several under development at Hella KGaA Hueck based on its ‘active light distribution’ and LED matrix-beam systems that put the headlamps under the control of camera-based pedestrian and object detection. The first products could be available as soon as 2009 but it is thought that systems to illuminate pedestrians or animals with LED ‘marker lights’ will not be ready until around 2015.
The matrix-beam is remarkable in that every LED chip lights up a defined area of the road in response to data on road conditions and oncoming traffic being analysed by the control module. Lighting patterns and beams for bend lighting, motorways and cornering can be realised without mechanically driven parts.
Such systems will automatically adapt their light distribution not only to the road and weather conditions, but also to the traffic situation. They are based on the interaction of image-producing sensors, powerful image processing software and lighting technology.
The first light-based driver assistance system to be controlled by image data will be the adaptive cut-off line and will use the current VarioX projection module rather than LED arrays. It will always set the range of the headlamps so that the driver has optimum visibility with the longest range possible. This is achieved through the adaptation of the headlamp range to preceding or oncoming motor vehicles. This means the low beam does not stop, as is usually the case today, at around 65m on the oncoming lane, but can in extreme cases be increased to several hundred metres. While maximising the possible visual range for the driver, dazzling other road-users is impossible as the headlamp cone always ends at their vehicles.
If the image-processing system does not detect any road users, the system can provide the driver with light up to the high-beam level. As soon as the camera detects other road users at up to approximately 800m, the range of the headlamps is adapted accordingly within milliseconds.
Between the light source and the projection lens in the VarioX projection module is a rotating drum contoured according to the advanced frontlighting system (AFS) light distributions. Using a stepper motor, it is rotated to the required position within milliseconds.
The marker light innovation behaves in exactly the opposite manner to glare-free high beam. Using an LED array-based AFS light distribution as a basis, pedestrians, animals and points of danger are specifically illuminated so that a driver is not only able to see them much earlier but also consciously detects them and can react accordingly.
Hella is working on multi-function camera systems that can integrate features such as lane recognition or traffic-sign recognition and adaptive cut-off line. Further added value is created through the fusion of the data of camera systems and other vehicle sensors.
Against this background, Hella is pursuing an ACC ‘stop & go’ system (deceleration to a standstill and moving off initiated by the driver) with the aid of an ACC infrared based LIDAR (light detection and ranging) sensor and a camera. A stereo camera approach is among those being considered. By exploiting depth information, stereo vision opens up spatial vision and therefore makes a significant contribution to object classification.
As a strategic investment in camera-based driver assistance systems, Hella took over 100% of Aglaia GmbH, Berlin, last year. The company specialises in visual sensor systems as key components of new types of driver assistance systems and integrates them into vehicles. Engineers have developed freely configurable inter-linkable application modules for lane, object, traffic-sign, headlamp and combination-rear-lamp recognition as well as rear-view camera systems.
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Author
Roger Bishop
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