Radar-based detection of objects while in motion
View Patent ↗A radar-based security screening system for detecting objects is described. The screening system includes a radar transmitter, a radar receiver, and a processing unit. In use, the radar transmitter steers a radar beam across a screening volume. The radar receiver, in turn, receives a return signal from an object over time as the object moves in the screening volume to create a three-dimensional temporal signature for the object. The processing unit classifies the three-dimensional temporal signature utilizing a classification process based on a deep neural network model, and provides an alert when the object is classified as an object of interest. During screening, a screened person is not required to remain still in a confined volume and is not exposed to harmful radiation.
1. A method for detecting and classifying an object, the method comprising the steps of:
steering a radar beam across a screening volume;
receiving a return signal from the object over time as the object moves in the screening volume to create a three-dimensional temporal signature for the object;
classifying the three-dimensional temporal signature utilizing a classification process based at a deep neural network model, the deep neural network model trained to process two four-dimensional tensors, each four-dimensional tensor based on a three-dimensional grid of voxels, each voxel describing the returned signal from a particular horizontal direction, a particular vertical direction and a particular depth in the screening volume; and
providing an alert when the object is classified as an object of interest.
2. The method of claim 1 , wherein the method further comprises the step of providing a level of confidence when an object is classified as an object of interest.
3. The method of claim 1 , wherein the received return signal is stored in a memory device as a data structure represented by the four-dimensional tensor.
4. The method of claim 1 , further comprising the step of inviting feedback on the classification process.
5. The method of claim 4 , further comprising the step of refining the classification process based at least in part on the feedback.
6. The method of claim 1 , wherein classifying the three-dimensional temporal signature utilizes video data from a video camera.
7. The method of claim 1 , wherein the step of providing an alert comprises raising, lowering, closing, or locking an object.
8. The method of claim 1 , wherein the radar beam has a wavelength between about one and about ten millimeters.
9. A screening system comprising:
a radar transmitter operative to steer a radar beam across a screening volume;
a radar receiver operative to receive a return signal from an object over time as the object moves in the screening volume to create a three-dimensional temporal signature for the object; and
a processing unit operative to classify the three-dimensional temporal signature utilizing a classification process based at least in part on a deep neural network model, the deep neural network model trained to process two four-dimensional tensors, each four-dimensional tensor based on a three-dimensional grid of voxels, each voxel describing the returned signal from a particular horizontal direction, a particular vertical direction and a particular depth in the screening volume, and to provide an alert when the object is classified as an object of interest.
10. The screening system of claim 9 , further comprising a memory storing computer readable program code executable by the logic circuitry.
11. The screening system of claim 9 , wherein the radar transmitter comprises a phased-array antenna.
12. The screening system of claim 9 , wherein the processing unit is further operative to provide a level of confidence when an object is classified as an object of interest.
13. The screening system of claim 9 , wherein the processing unit is further operative to invite feedback on the classification process.
14. The screening system of claim 13 , wherein the processing unit is further operative to refine the classification process based at least in part on the feedback.
15. The screening system of claim 9 , further comprising an alarm that may be activated by the processing unit upon classifying an object of interest.
16. The screening system of claim 9 , wherein the radar receiver is operative to resolve one or more angles of arrival of the return signal.
17. The screening system of claim 9 , further comprising a video camera providing video data, wherein the processing unit is further operative to utilize the video data in the classification process.
18. The screening system of claim 9 , wherein the radar beam has a wavelength between about one and about ten millimeters.