METHOD AND SYSTEM FOR LOCALIZATION OF A VEHICLE USING SURFACE PENETRATING RADAR

• US 20180217251A1
• Filed: 12/04/2017
• Published: 08/02/2018
• Est. Priority Date: 01/27/2017
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Stanley, Byron McCall, Cornick, Matthew Tyler
• Granted Patent: US 10,725,171 B2
• Time in Patent Office: Days
• CPC Class Codes: B60W 2420/408 Radar; Laser, e.g. lidar
• CPC Class Codes: B60W 2420/52 Radar, Lidar
• CPC Class Codes: B60W 2422/00 Indexing codes relating to the special location or mounting of sensors
• CPC Class Codes: B60W 2552/00 Input parameters relating to infrastructure
• CPC Class Codes: B60W 40/06 Road conditions
• CPC Class Codes: B60W 40/064 Degree of grip
• CPC Class Codes: B60W 40/068 Road friction coefficient
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01C 21/3602 Input other than that of destination using image analysis, e.g. detection of road signs, lanes, buildings, real preceding vehicles using a camera
• CPC Class Codes: G01S 13/862 Combination of radar systems with sonar systems
• CPC Class Codes: G01S 13/865 Combination of radar systems with lidar systems
• CPC Class Codes: G01S 13/867 Combination of radar systems with cameras
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/872 Combinations of primary radar and secondary radar
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 13/951 ground based
• CPC Class Codes: G01S 2013/9327 Sensor installation details
• CPC Class Codes: G01S 7/411 Identification of targets based on measurements of radar reflectivity G01S7/415 takes precedence

Abstract

A method and a surface penetrating radar (SPR) system for localization of a vehicle are disclosed. The method includes transmitting a radar signal having a first frequency into a subsurface region adjacent to a vehicle. A first set of SPR images of a first subsurface volume within the subsurface region is acquired and location data for the vehicle are determined from the first set of SPR images. A second radar signal having a frequency that is greater than the first frequency is transmitted into the subsurface region and a second set of SPR images of a second subsurface volume within the subsurface region is acquired. The second subsurface volume at least partially overlaps the first subsurface volume. Location data are determined from the second set of SPR images at a greater resolution than the location data determined from the first set of SPR images.

Claims

1. A method for localization of a vehicle, the method comprising:

transmitting a first radar signal having a first frequency into a subsurface region under a vehicle;

transmitting a second radar signal having a second frequency into the subsurface region, the second frequency being greater than the first frequency;

acquiring a first set of surface penetrating radar (SPR) images of a first subsurface region based on the first radar signal;

acquiring a second set of SPR images of a second subsurface region at least partially overlapping the first subsurface region based on the second radar signal;

determining location data for the vehicle based on the first set of SPR images; and

determining location data for the vehicle based on the second set of SPR images.

2. The method of claim 1 wherein the first radar signal has a first plurality of frequencies and the second radar signal has a second plurality of frequencies.

3. The method of claim 2 wherein the first and second pluralities of frequencies includes overlap frequencies.

4. The method of claim 1 wherein the first radar signal and/or the second radar signal comprise a ramp of discrete frequencies over time.

5. The method of claim 1 wherein the first radar signal and the second radar signal are transmitted simultaneously.

6. The method of claim 2 wherein the second plurality of frequencies includes all the frequencies of the first plurality of frequencies.

7. The method of claim 2 wherein the first plurality of frequencies includes all the frequencies of the second plurality of frequencies.

8. The method of claim 1 wherein the step of determining location data for the vehicle based on the first set of SPR images generates location data at a first resolution, wherein the step of determining location data for the vehicle based on the second set of SPR images is further based on the location data at the first resolution and generates location data at a second resolution, and wherein the second resolution is greater than the first resolution.

9. The method of claim 1 wherein a depth of the second subsurface region is smaller than a depth of the first subsurface region.

10. The method of claim 1 wherein the first radar signal and the second radar signal is a single radar signal that includes the first and second frequencies.

11. The method of claim 1 wherein the first and second radar signals are transmitted from a same radar transmitter element.

12. The method of claim 1 wherein the first and second radar signals are transmitted from different radar transmitter elements.

13. The method of claim 1 further comprising controlling the movement of the vehicle in response to the location data.

14. The method of claim 1 further comprising:

transmitting into the subsurface region at least one additional radar signal each having a frequency content that is different from the first radar signal, the second radar signal, and each of the other additional radar signals;

acquiring an additional set of SPR images for each of the additional radar signals; and

determining location data for the vehicle based on the additional sets of SPR images.

15. The method of claim 1 further comprising:

transmitting one or more intermediate radar signals into the subsurface region, each of the intermediate radar signals having an intermediate frequency that is greater than the first frequency and less than the second frequency, and each of the intermediate frequencies being different from each of the other intermediate frequencies;

for each of the intermediate radar signals, acquiring an intermediate set of SPR images of an intermediate subsurface region; and

for each intermediate set of SPR images, determining location data for the vehicle based on a corresponding one of the intermediate sets of SPR images.

16. The method of claim 1 wherein the acquiring of the first and second sets of SPR images comprises applying a range gate to a first received radar signal and a second received radar signal, respectively, from the subsurface region.

17. The method of claim 1 wherein at least one of the first frequency and the second frequency are selected based on a property of one or more features in the subsurface region.

18. The method of claim 1 wherein at least one of the first and second sets of SPR images includes SPR images that are weighted according to depth.

19. The method of claim 1 wherein at least one of the first and second sets of SPR images includes SPR images having depths that are excluded.

20. A surface penetrating radar (SPR) system, comprising:

an SPR antenna array comprising a plurality of antenna elements and configured to transmit a first radar signal having a first frequency and a second radar signal having a second frequency into a subsurface region adjacent to a vehicle, the second frequency being greater than the first frequency, the antenna elements further configured to receive a return radar signal from the subsurface region;

a radar processor in communication with the SPR antenna array, the radar processor configured to;

acquire a first set of SPR images of a first subsurface region based on the first radar signal; and

acquiring a second set of SPR images of a second subsurface region at least partially overlapping the first subsurface region based on the second radar signal; and

a registration module in communication with the processor, the registration module configured to;

determine location data for the vehicle based on the first set of SPR images; and

determine location data for the vehicle based on the second set of SPR images.

21. The SPR system of claim 20 wherein the SPR antenna array is further configured to transmit into the subsurface region at least one additional radar signal each having a frequency content that is different from the first radar signal, the second radar signal, and each of the other additional radar signals, and wherein the radar processor is further configured to acquire an additional set of SPR images for each of the additional radar signals.

22. The SPR system of claim 21 wherein the registration module is further configured to determine location data for the vehicle based on the additional sets of SPR images and location data previously determined for the vehicle.

23. The SPR system of claim 20 wherein the SPR antenna array is further configured to transmit one or more intermediate radar signals into the subsurface region, each of the intermediate radar signals having an intermediate frequency that is greater than the first frequency and less than the second frequency, and each of the intermediate frequencies being different from each of the other intermediate frequencies, and wherein the radar processor is further configured, for each of the intermediate radar signals, to acquire an intermediate set of SPR images of an intermediate subsurface region.

24. The SPR system of claim 23 wherein the registration module is further configured, for each intermediate set of SPR images, to determine location data for the vehicle based on a corresponding one of the intermediate sets of SPR images and location data previously determined for the vehicle.