Seite - 17 - in Integration of Advanced Driver Assistance Systems on Full-Vehicle Level - Parametrization of an Adaptive Cruise Control System Based on Test Drives

2.2. Environmental-Recognition Sensors xs ys iϕ xs ys iϕ Tx1 Tx2 ϕsiϕ P ϕsiϕ P Tx1Tx2 (b)(a) S S Figure 2.9.: (a) Scanning RADAR and (b) Multi-Beam RADAR, adapted from [Win09] 2.2.2. Video Camera Common video cameras are passive sensors, which are very similar to the human eyes. Therearealsoactivecameras,whichemitvisibleor infrared light. If infrared light isused, they are most often used as Perception Improvement Systems (PIS), see appendix A.7. Time of Flight (TOF) cameras, which emit visible light, are able to detect the depth coordinate for every pixel in the generated picture, [BLR09]. Since active cameras are not used in production ACC systems, they are not described in detail in this work. Common cameras consist of lenses, the imager and the signal processing unit. The lens bundles the divergent light reflected by the object to convergent light and projects the picture of the object onto the imager, see fig. 2.10(a). The imager discretises the picture and sends the digital image to the signal processing unit, where the features used by the ADAS are extracted. Camera systems can be used to detect lane markings in order to ensure proper target selection or to detect objects to support another sensor(s), most often RADAR sensor(s), in the object classification, [SBD09]. Mono Camera Stein et al. showed in [SMS03] that it is possible to use a single mono camera for ACC systems. Using the height of the camera above ground, the distance to the object can be estimated. In this case the target has to stand on the same planar surface as the ego vehicle that is equipped with the camera. If this is not the case, the non-planarity can be compensated by using lane markings detected by the camera. 17