This application is a Non-Provisional of U.S. Provisional Patent Application Ser. No. 62/052,721 filed Sep. 19, 2014, the disclosure of which is incorporated by reference herein in its entirety.
The subject invention relates to detection of a distributed radar target using measurements from an auxiliary sensor.
Radio detection and ranging (radar) systems are used in a wide variety of arenas. For example, radar systems detect airplanes for air traffic control, marine radar systems detect landmarks or other ships, and ground-penetrating radar systems detect geological features. In automobiles, radar systems may be used to detect obstacles for a variety of purposes. Based on the distance from the radar system to the object being detected (the target), the target may be represented as a random cluster of multiple point scatters or reflection points. This is the case for obstacles detected by a radar system in an automobile, for example. Another automobile in front of the automobile equipped with the radar system would return point reflections based on transmitted pulses.
According to an exemplary embodiment, a detection system to detect an object includes a radar system configured to transmit radiation and receive resulting reflections, the object being a distributed radar target reflecting multi-point reflections; an auxiliary sensor configured to estimate one or more parameters of the object; and a processor configured to estimate a probability density function based on estimates of the one or more parameters of the object and the multi-point reflections and to detect the object based on the probability density function.
According to another embodiment, a method of performing detection of an object includes obtaining, using a radar system, multi-point reflections resulting from each transmission by the radar system; obtaining, using an auxiliary sensor, an estimate of one or more parameters of the object; estimating a probability density function based on the estimate of the one or more parameters of the object and the multi-point reflections; and detecting the object based on the probability density function.
The above features and advantages and other features and advantages of the invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.
Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
As noted above, for some radar systems (e.g., those in automobiles) target objects are represented as a random cluster of multiple point reflectors. When a cluster of reflections belonging to the same object is estimated together rather than individually, detection (identification) of the object is made more accurate. However, not every reflection received by the radar system may be attributable to a single object. One or more reflections may result from other objects instead. Thus, the approach of estimating the cluster of reflections together benefits from knowledge of the probability density function (PDF) associated with the physical characteristics, location, and velocity of an object of the target object. The physical characteristics include, for example, size, orientation, material, and surface roughness. A consideration in using the PDF for object identification is that there may be a large set of possible objects and a large variation in the object characteristics and appearances. Also, different configurations of possible objects may yield similar received radar signals, thereby creating ambiguity in the target identification. A PDF estimated by taking into consideration all of the possibilities may be too general to have a relation to a specific object configuration and thereby aid in the identification of the object. Embodiments of the system and method discussed herein relate to using one or more auxiliary sensors (auxiliary to the radar system) to detect a distributed radar target (i.e., a radar target that is not a point reflector but, instead, is a multi-point reflector). Specifically, each auxiliary sensor improves the PDF estimation used to perform the object detection by further constraining the parameters used to estimate PDF.
The processor 115 performs a parameterized PDF estimation based on inputs from the radar system 120 and the one or more auxiliary systems 130. That is, based on parameters such as distance (location), size, shape, material, and texture, for example, provided by the one or more auxiliary systems 130, the processor 115 obtains an enhanced estimate of PDF of the detected object 140 from the reflections received by the radar system 120. The parameter information provided by the one or more auxiliary systems 130 constrains the PDF estimate further. The processor 115 may perform object detection using a maximum likelihood estimator, for example. With Ω representing a cluster of reflections associated with the same object (based on a probability that the reflections belong to the same object), A representing object characteristics (e.g., size, orientation, material, surface roughness) obtained from the one or more auxiliary systems 130, and Y representing the point reflections received by the radar system 120, the maximum likelihood used for object detection is given by:
{circumflex over (Ω)}=arg maxΩf(Y|Ω,Λ) [EQ. 1]
The function may be, for example, a correlated Gaussian distribution.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the application.
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20160084954 A1 | Mar 2016 | US |
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62052721 | Sep 2014 | US |