Vehicular radar system with automatic sensor alignment

Patent metadata

Field	Value
Publication number	US-12044794-B2
Application number	US-202217648835-A
Country	US
Kind code	B2
Filing date	Jan 25, 2022
Priority date	Feb 26, 2019
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

A method includes disposing a spherical radar reflector at a location exterior a vehicle equipped with the vehicular sensing system. The vehicular sensing system includes at least two radar sensors disposed at the vehicle and a controller that processes received radio frequency (RF) signals received by the plurality of receivers of each radar sensor of the at least two radar sensors. Calibration RF signals are transmitted by at least one transmitting antenna of a plurality of transmitters of a first radar sensor and a second radar sensor the at least two radar sensors, and reflected first calibration RF signals are received by the plurality of receivers of the first radar sensor and the second radar sensor. Based on a distance between the first radar sensor, the second radar sensor, and the spherical reflector, the vehicular sensing system determines an orientation of the first radar sensor and the second radar sensor.

First claim

The invention claimed is:

1. A method for calibrating a vehicular sensing system, the method comprising:
disposing a spherical radar reflector at a calibration location exterior a vehicle equipped with the vehicular sensing system;
wherein the vehicular sensing system of the equipped vehicle comprises at least two radar sensors disposed at the vehicle so as to have respective fields of sensing exterior of the vehicle, and wherein each radar sensor of the at least two radar sensors comprises a plurality of transmitting antennas that, during operation of the respective radar sensor, transmits radio frequency (RF) signals, and wherein each radar sensor of the at least two radar sensors comprises a plurality of receiving antennas that receive RF signals, and wherein the received RF signals are transmitted RF signals that are reflected from an object present in the field of sensing of the respective radar sensor;
wherein the vehicular sensing system at the equipped vehicle comprises an electronic control unit (ECU), the ECU comprising a data processor that processes radar data derived from RF signals received by the plurality of receiving antennas of the at least two radar sensors and provided to the ECU;
wherein, with the spherical radar reflector disposed at the calibration location exterior the vehicle, the calibration location of the spherical radar reflector relative to the vehicle comprises a location where the fields of sensing of a first radar sensor of the at least two radar sensors and a second radar sensor of the at least two radar sensors overlap;
transmitting first calibration RF signals by at least one transmitting antenna of the plurality of transmitting antennas of the first radar sensor;
receiving, by the plurality of receiving antennas of the first radar sensor, reflected first calibration RF signals, wherein the reflected first calibration RF signals at least comprise the first calibration RF signals transmitted by the at least one transmitting antenna of the plurality of transmitting antennas of the first radar sensor and reflected off the spherical radar reflector;
determining a first distance between the first radar sensor and the spherical radar reflector based on the received reflected first calibration RF signals;
transmitting second calibration RF signals by at least one transmitting antenna of the plurality of transmitting antennas of the second radar sensor;
receiving, by the plurality of receiving antennas of the second radar sensor, reflected second calibration RF signals, wherein the reflected second calibration RF signals at least comprise the second calibration RF signals transmitted by the at least one transmitting antenna of the plurality of transmitting antennas of the second radar sensor and reflected off the spherical radar reflector;
determining a second distance between the second radar sensor and the spherical radar reflector based on the received reflected second calibration RF signals;
transmitting third calibration RF signals by at least one transmitting antenna of the plurality of transmitting antennas of the first radar sensor;
receiving, by the plurality of receiving antennas of the second radar sensor, reflected third calibration RF signals, wherein the reflected third calibration RF signals at least comprise the transmitted third calibration RF signals transmitted by the at least one transmitting antenna of the plurality of transmitting antennas of the first radar sensor and reflected off the spherical radar reflector;
determining, based on the received reflected third calibration RF signals, a radar signal path distance from the first radar sensor to the second radar sensor via the spherical radar reflector; and
determining a location and an orientation of the first radar sensor relative to the vehicle and a location and an orientation of the second radar sensor relative to the vehicle based on the determined first distance, the determined second distance, and the determined radar signal path distance.

2. The method of claim 1 , wherein transmitting calibration RF signals comprises transmitting a fixed transmission code known to each radar sensor of the at least two radar sensors.

3. The method of claim 1 , comprising configuring the vehicular sensing system to enter a calibration mode by placing the plurality of receiving antennas of the at least two radar sensors into a listening mode.

4. The method of claim 1 , wherein determining the location and orientation of the first and second radar sensors relative to the vehicle comprises determining at least one selected from the group consisting of (i) roll of the respective radar sensor relative to the vehicle, (ii) pitch of the respective radar sensor relative to the vehicle and (iii) yaw of the respective radar sensor relative to the vehicle.

5. The method of claim 4 , wherein determining the location and orientation of the first radar sensor relative to the vehicle comprises using long baseline techniques.

6. The method of claim 5 , wherein determining the location and orientation of the first radar sensor relative to the vehicle comprises using triangulation.

7. The method of claim 1 , wherein determining the location and orientation of the first radar sensor relative to the vehicle comprises determining a misalignment of the first radar sensor relative to the vehicle and adjusting processing of radar data derived from RF signals received by the plurality of receiving antennas of the first radar sensor to accommodate the determined misalignment of the first radar sensor relative to the vehicle.

8. The method of claim 7 , wherein determining the location and orientation of the first radar sensor relative to the vehicle comprises storing in nonvolatile memory offsets for the first radar sensor relative to the vehicle based on the respective determined misalignment.

9. The method of claim 1 , wherein transmitting calibration RF signals comprises sequentially transmitting calibration RF signals from the respective radar sensors of the at least two radar sensors.

10. The method of claim 1 , wherein the vehicular sensing system comprises a camera, and wherein the method comprises verifying an alignment of the camera based on the determined location and orientation of the first radar sensor relative to the vehicle and the determined location and orientation of the second radar sensor relative to the vehicle.

11. The method of claim 1 , wherein the vehicular sensing system comprises an inertial measurement unit (IMU), and wherein the method comprises compensating measured radar responses to dynamic changes of the at least two radar sensors based on inputs received from the IMU.

12. The method of claim 1 , wherein determining the radar signal path distance between the first radar sensor and the second radar sensor via the spherical radar reflector comprises determining, via a time synchronization signal, an amount of time elapsed between transmitting the third calibration RF signals by the at least one transmitting antenna of the plurality of transmitting antennas of the first radar sensor and receiving, by the plurality of receiving antennas of the second radar sensor, the reflected third calibration RF signals.

13. The method of claim 12 , wherein determining the amount of time elapsed comprises using a synchronization trigger signal.

14. A method for calibrating a vehicular sensing system, the method comprising:
disposing a spherical radar reflector at a calibration location exterior a vehicle equipped with the vehicular sensing system;
wherein the vehicular sensing system of the equipped vehicle comprises at least two radar sensors disposed at th

Assignees

• Magna Electronics Inc

Inventors

• Wodrich Helmut A
• Hess Holger
• Pliefke Sebastian
• Woodington Walter G

Classifications

• G01S13/87

  Combinations of radar systems, e.g. primary radar and secondary radar · CPC title

• G01S13/867

  Combination of radar systems with cameras · CPC title

• G01S7/40

  Means for monitoring or calibrating · CPC title

• G01S13/931

  of land vehicles · CPC title

• G01S7/4021

  of receivers · CPC title