System and method for radar based mapping for autonomous robotic devices

1. An autonomous device comprising:

a radar system including a transmitter and two spaced apart receivers spaced apart by half a wavelength or less, wherein the transmitter is configured to produce a radar chirp and each receiver is configured to receive raw radar data corresponding to a reflection of the radar chirp;

a processor; and

a memory, storing instructions which when executed by the processor causes the processor to:

approximate a peak in the respective radar data from each of the spaced apart receivers;

determine a phase difference between the respective peaks;

determine a Doppler speed associated with the raw radar data;

determine a direction of arrival (DOA) based on the approximated peaks, the phase difference, and the Doppler speed;

generate a reprojection map based on the DOA and the approximated peaks; and

update a map using the reprojection map.

2. The device of claim 1 , further comprising instructions which when executed by the processor, causes the processor to smooth the received raw radar data.

3. The device of claim 2 , further comprising instructions which when executed by the processor, causes the processor to apply a Gaussian transform to the received raw radar data.

4. The device of claim 1 , further comprising instructions which when executed by the processor, causes the processor to:

retrieve a stored value associated with a stored distance, a stored direction of arrival, and a pixel in the map;

detect a direction of arrival and a distance corresponding to the pixel; and

modify the stored value based on a comparison of the stored direction of arrival and the stored distance to the detected direction of arrival and the detected distance.

5. The device of claim 1 , further comprising instructions which when executed by the processor, causes the processor to:

receive a range profile, the range profile corresponding to a stored value for a pixel in the map;

modify the stored value for the pixel based at least in part on the received range profile; and

modify a stored value for a neighboring pixel in the map based at least in part on one of the received range profile or the modified value for the pixel.

6. The device of claim 5 , further comprising instructions which when executed by the processor, causes the processor to modify the stored value for the neighboring pixel based on a distance between the neighboring pixel and the pixel.

7. The device of claim 1 , wherein at least one of the spaced apart receivers includes a horn extension.

8. A system for updating a map, the system comprising:

a radar system including a transmitter and three spaced apart receivers disposed in a non-collinear arrangement, wherein the transmitter is configured to produce a radar chirp and each receiver is configured to receive raw radar data corresponding to a reflection of the radar chirp;

a processor; and

a memory, storing instructions which when executed by the processor causes the processor to:

approximate a peak in the respective radar data from each of the spaced apart receivers;

determine a phase difference between the respective peaks;

determine a Doppler speed associated with the raw radar data;

determine a direction of arrival based on the approximated peaks, the phase difference, and the Doppler speed;

generate a reprojection map based on the DOA and the approximated peaks; and

update a map using the reprojection map;

wherein approximating the peak and determining the phase difference is performed with respect to a selected two of the three receivers.

9. The system of claim 8 , further comprising instructions which when executed by the processor, causes the processor to smooth the received raw radar data.

10. The system of claim 9 , further comprising instructions which when executed by the processor, causes the processor to apply a Gaussian transform to the received raw radar data.

11. The system of claim 8 , further comprising instructions which when executed by the processor, causes the processor to:

retrieve a stored value associated with a stored distance, a stored direction of arrival, and a pixel in the map;

detect a direction of arrival and a distance corresponding to the pixel; and

modify the stored value based on a comparison of the stored direction of arrival and the stored distance to the detected direction of arrival and the detected distance.

12. The system of claim 8 , further comprising instructions which when executed by the processor, causes the processor to:

receive a range profile, the range profile corresponding to a stored value for a pixel in the map;

modify the stored value for the pixel based at least in part on the received range profile; and

modify a stored value for a neighboring pixel in the map based at least in part on one of the received range profile or the modified value for the pixel.

13. The system of claim 12 , further comprising instructions which when executed by the processor, causes the processor to modify the stored value for the neighboring pixel based on a distance between the neighboring pixel and the pixel.

14. An autonomous device comprising:

a radar system including a transmitter and three spaced apart receivers disposed in a non-collinear arrangement, wherein the transmitter is configured to produce a radar chirp and each receiver is configured to receive raw radar data corresponding to a reflection of the radar chirp;

a processor; and

a memory, storing instructions which when executed by the processor causes the processor to:

approximate a peak in the respective radar data from each of the spaced apart receivers;

determine a phase difference between the respective peaks;

determine a Doppler speed associated with the raw radar data;

determine a direction of arrival (DOA) based on the approximated peaks, the phase difference, and the Doppler speed;

generate a reprojection map based on the DOA and the approximated peaks; and

update a map using the reprojection map;

wherein approximating the peak and determining the phase difference is performed with respect to a selected two of the three receivers.

15. The device of claim 14 , further comprising instructions which when executed by the processor, causes the processor to smooth the received raw radar data.

16. The device of claim 15 , further comprising instructions which when executed by the processor, causes the processor to apply a Gaussian transform to the received raw radar data.

17. The device of claim 14 , further comprising instructions which when executed by the processor, causes the processor to:

retrieve a stored value associated with a stored distance, a stored direction of arrival, and a pixel in the map;

detect a direction of arrival and a distance corresponding to the pixel; and

modify the stored value based on a comparison of the stored direction of arrival and the stored distance to the detected direction of arrival and the detected distance.

18. The device of claim 14 , further comprising instructions which when executed by the processor, causes the processor to:

receive a range profile, the range profile corresponding to a stored value for a pixel in the map;

modify the stored value for the pixel based at least in part on the received range profile; and

modify a stored value for a neighboring pixel in the map based at least in part on one of the received range profile or the modified value for the pixel.

19. The device of claim 18 , further comprising instructions which when executed by the processor, causes the processor to modify the stored value for the neighboring pixel based on a distance between the neighboring pixel and the pixel.

20. The device of claim 14 , wherein the radar chirp duration is in the range of 5 to 15 milliseconds.