Calibrating a radar antenna
In one embodiment, a method includes causing a radar antenna to transmit a plurality of radar signals at a plurality of sweep angles and, for each of one or more the radar signals reflected back to the radar antenna, calculating a radial-velocity component. The method also includes identifying one of the radial-velocity components, identifying one of the plurality of sweep angles corresponding to the identified radial-velocity components, and calculating an offset of an electrical boresight of the radar antenna based at least in part on the identified sweep angle corresponding to the identified radial-velocity component.
1. A method comprising, by a computing device:
causing a radar antenna to transmit radar signals at a plurality of sweep angles;
calculating a respective value of a radial-velocity component corresponding to one or more reflected radar signals of the transmitted radar signals reflected back to the radar antenna;
identifying one or more of the one or more radial-velocity components based on the one or more respective values of the one or more radial-velocity components;
identifying a sweep angle of the plurality of sweep angles corresponding to the one or more identified radial-velocity components;
calculating an offset between an actual electrical boresight of the radar antenna based at least in part on the identified sweep angle corresponding to the one or more identified radial-velocity components and an expected electrical boresight of the radar antenna; and
causing the radar antenna to be calibrated based on the calculated offset.
2. The method of claim 1 , wherein causing the radar antenna to be calibrated comprises causing the calculated offset to be accounted for in future measurements by the radar antenna.
3. The method of claim 1 , wherein causing the radar antenna to be calibrated comprises causing an orientation of the radar antenna to be changed based at least in part on the calculated offset.
4. The method of claim 1 , wherein:
the radar antenna transmits the radar signals in one or more horizontal sweeps; and
the calculated offset of the actual electrical boresight of the radar antenna is horizontal.
5. The method of claim 1 , wherein:
the radar antenna transmits the radar signals in one or more vertical sweeps; and
the calculated offset of the actual electrical boresight of the radar antenna is vertical.
6. The method of claim 1 , wherein the reflected radar signals are reflected from a plurality of locations on a substantially planar surface moving at a substantially constant velocity relative to the radar antenna.
7. The method of claim 1 , wherein the reflected radar signals are reflected from a plurality of locations on a surface of a sphere rotating at a constant speed in front of the radar antenna.
8. The method of claim 1 , wherein the radar antenna is located in or on a vehicle.
9. The method of claim 8 , wherein the vehicle is an autonomous vehicle.
10. The method of claim 8 , wherein the radar antenna is located:
on top of the vehicle; or
on or in a bumper of the vehicle.
11. A system comprising: one or more processors; and one or more computer-readable non-transitory storage media in communication with the one or more processors, the one or more computer-readable non-transitory storage media comprising instructions that, when executed by the one or more processors, are configured to cause the system to perform operations comprising:
causing a radar antenna to transmit radar signals at a plurality of sweep angles;
calculating a respective value of a radial-velocity component corresponding to one or more reflected radar signals of the transmitted radar signals reflected back to the radar antenna;
identifying one or more of the one or more radial-velocity components based on the one or more respective values of the one or more radial-velocity components;
identifying a sweep angle of the plurality of sweep angles corresponding to the one or more identified radial-velocity components;
calculating an offset between an actual electrical boresight of the radar antenna based at least in part on the identified sweep angle corresponding to the one or more identified radial-velocity components and an expected electrical boresight of the radar antenna; and
causing the radar antenna to be calibrated based on the calculated offset.
12. The system of claim 11 , wherein causing the radar antenna to be calibrated comprises causing the calculated offset to be accounted for in future measurements by the radar antenna.
13. The system of claim 11 , wherein causing the radar antenna to be calibrated comprises causing an orientation of the radar antenna to be changed based at least in part on the calculated offset.
14. The system of claim 11 , wherein:
the radar antenna transmits the radar signals in one or more horizontal sweeps; and
the calculated offset of the actual electrical boresight of the radar antenna is horizontal.
15. The system of claim 11 , wherein:
the radar antenna transmits the radar signals in one or more vertical sweeps; and
the calculated offset of the actual electrical boresight of the radar antenna is vertical.
16. The system of claim 11 , wherein the reflected radar signals are reflected from a plurality of locations on a substantially planar surface moving at a substantially constant velocity relative to the radar antenna.
17. One or more computer-readable non-transitory storage media including instructions that, when executed by one or more processors of a computing system, are configured to cause the one or more processors to perform operations comprising:
causing a radar antenna to transmit radar signals at a plurality of sweep angles;
calculating a respective value of a radial-velocity component corresponding to one or more reflected radar signals of the transmitted radar signals reflected back to the radar antenna;
identifying one or more of the one or more radial-velocity components based on the one or more respective values of the one or more radial-velocity components;
identifying a sweep angle of the plurality of sweep angles corresponding to the one or more identified radial-velocity components;
calculating an offset between an actual electrical boresight of the radar antenna based at least in part on the identified sweep angle corresponding to the one or more identified radial-velocity components and an expected electrical boresight of the radar antenna; and
causing the radar antenna to be calibrated based on the calculated offset.
18. The one or more computer-readable non-transitory storage media claim 17 , wherein the reflected radar signals are reflected from a plurality of locations on a substantially planar surface moving at a substantially constant velocity relative to the radar antenna.
19. The one or more computer-readable non-transitory storage media claim 17 , wherein the reflected radar signals are reflected from a plurality of locations on a surface of a sphere rotating at a constant speed in front of the radar antenna.
20. The method of claim 8 , wherein the calculated offset corresponds to the actual electrical boresight of the radar antenna being misaligned with a central longitudinal axis of the vehicle.
21. The method of claim 1 , wherein the actual electrical boresight of the radar antenna corresponds to an axis of maximum radiated power of the radar antenna.
22. The method of claim 1 , wherein one of the one or more identified radial-velocity components is a maximum radial-velocity component.
23. The method of claim 1 , wherein identifying the sweep angle of the plurality of sweep angles corresponding to the one or more identified radial-velocity components comprises calculating a sweep angle based on the one or more identified radial-velocity components.