This invention is related to radar systems for automotive hazard detection. More particularly, this invention relates to improvements in discrimination of bona fide hazard targets from various non-hazard targets and/or clutter commonly encountered in the typical automotive operating environment.
Many attempts at providing reliable hazard target discrimination have been carried out in the field of vehicular radar systems which provide target range and relative velocity measurements thereof. The operating environment of an automotive radar system presents many challenges to the system designer, among the most troublesome being differentiation between hazard and non-hazard targets, both of which return transmitted radar signals. Typical non-hazard targets include road signs, bridges, fences, guard rails and road-side burms, etc. Poor discrimination of such non-hazards from hazards of course limits the effectiveness and reliability of automotive radar systems.
Various attempts in the art have been made to remedy these radar system shortfalls. One such example of these attempts includes limiting the range and pattern width of signal transmission and reception which in turn also undesirably limits the area of detection. This is an especially unattractive option where, as in a vehicle blind-zone detection radar system, a relatively wide area needs to be covered. Other proposals for solving these radar system shortfalls includes multiple transmitter and/or receiver configurations which of course add complexity and cost. Variable transmitted radar pattern angle and range, interactive in response to steering input, have also been proposed to limit return signals from non-hazard targets such as those which are tangential to a vehicle's travel around a curve or bend. This technique may be useful for look-ahead or look-back radar systems where radar pattern is substantially aligned with the major axis of the vehicle but does not address the problems of blind-zone radar systems where the transmission pattern is intentionally at an angle from the major axis of the vehicle. Additionally, relatively complicated return signal processing to separate multipath signals in frequency bands have been proposed to discriminate between multiple targets.