Several competing and potentially complementary technologies exist for collision avoidance systems for cars. Ultrasonic sensors are in widespread use for parking aids, but with a typical range of less than 3 m and no facility for accurate object or speed discrimination, this technology can't meet advanced safety objectives. More promising approaches include conventional and infrared imaging as well as laser techniques. But alone, each of these technologies suffers from susceptibility to poor environmental conditions, such as fog or road spray. Low-power radar isn't immune from these conditions but is far more tolerant, especially at lower frequencies at which environmental-absorption characteristics are less significant. As a result, most studies agree that radar is the single most promising technology. EU and US authorities research radar-based accident-reduction technologies. Millimeter-wave ACCs (Adaptive Cruise Controllers) at 77 GHz herald autonomous systems. ACC radars use pulse-modulated continuous-wave techniques, frequency-modulated continuous-wave techniques, or both. FMCW (Frequency-Modulated Continuous-Wave) systems modulate the carrier with a triangular waveform to derive range and relative velocity Information from sum-and-difference beat frequencies. Industry proposes lower frequencies, such as 24 GHz, to cut cost.
Radar reflects safer highways
Einsatz der Radartechnik für den Kollisionsschutz bei Kraftfahrzeugen
EDN Europe ; 48 , 3 ; 21-28
2003
7 Seiten, 5 Bilder
Article (Journal)
English
British Library Online Contents | 2007
Looking forward to safer highways
Automotive engineering | 2008
|Roundabouts: A Direct Way to Safer Highways
Online Contents | 1995
|