Apparatus and method for detecting radar obstruction

• US 6,469,659 B1
• Filed: 05/03/2001
• Issued: 10/22/2002
• Est. Priority Date: 05/03/2001
• Status: Expired due to Term

• Current Assignee: Aptiv Technologies Limited (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Lajiness, Gregory George, Alland, Stephen William, Searcy, James Fredrick
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/847,207
• Publication Number:
  US 20020163463A1
• Time in Patent Office: 537 Days
• Field of Search: 342/70, 342/71, 342/72, 342/159-175, 342/192-197, 342/27, 342/28, 342/89-103
• US Class Current: 342/173
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G01S 2013/93274 on the side of the vehicles
• CPC Class Codes: G01S 2013/93275 in the bumper area
• CPC Class Codes: G01S 7/4004 of parts of a radar system
• CPC Class Codes: G01S 7/4039 of sensor or antenna obstruction, e.g. dirt- or ice-coating

Abstract

An apparatus and method for detecting radar system blockage includes a radar system having an antenna unit configured to transmit radar signals and receive reflected radar signals. In one embodiment, fixed frequency continuous wave radar signals are transmitted, and corresponding reflected signals are sampled and processed to determine a mainbeam clutter signal peak in frequency bins near those corresponding to vehicle speed. If this peak is less than a power threshold, the antenna unit is at least partially blocked. In another embodiment, a number of most recent reflected tracking signal amplitudes are sampled, normalized to a predefined range value and filtered to produce a smoothed tracking amplitude. If the smoothed tracking amplitude drops below an amplitude threshold, the antenna unit is at least partially blocked. The two embodiments may be combined to determine a radar antenna blockage status as a function of both techniques.

Claims

1. System for detecting radar blockage, comprising:

a radar unit having an antenna configured for transmitting radar signals and for receiving reflected radar signals;

a vehicle speed sensor producing a vehicle speed signal indicative of a travelling speed of a vehicle carrying said radar unit; and

a control computer responsive to at least some of said reflected radar signals to compute a relative radar power signal as a function of frequency, said control computer responsive to said vehicle speed signal to determine a mainbeam clutter peak of said relative radar power signal along a number of Doppler frequencies defined by said travelling speed, said control computer setting a first radar blockage flag if said mainbeam clutter peak is below a power threshold value.

2. The system of claim 1 wherein said at least some of said reflected radar signals correspond to continuous wave radar signals.

3. The system of claim 1 wherein said control computer is operable to determine said relative radar power signal by transforming said at least some of said reflected radar signals along discrete frequency bins.

4. The system of claim 3 wherein said control computer is operable to determine said mainbeam clutter peak as a maximum value of said relative radar power signal among a number of said discrete Doppler frequency bins defined by said travelling speed.

5. The system of claim 1 wherein said control computer is operable to determine that said radar antenna is at least partially blocked if said first radar blockage flag is set.

6. The system of claim 1 wherein said control computer is responsive to said reflected radar signals to track at least one object external to said vehicle, said control computer normalizing corresponding tracking amplitudes of said reflected radar signals to a predefined tracking distance and filtering said normalized tracking amplitudes to produce a smoothed tracking amplitude, said control computer setting a second radar blockage flag if said smoothed tracking amplitude drops below an amplitude threshold value.

7. The system of claim 6 wherein said control computer is operable to determine a radar blockage state associated with said antenna as a function of said first and second radar blockage flags.

8. The system of claim 7 wherein said control computer is operable to determine that said antenna is at least partially blocked if either of said first and second radar blockages flags is set.

9. System for detecting radar blockage, comprising:

a radar unit carried by a motor vehicle, said radar unit having an antenna configured for transmitting radar signals and for receiving reflected radar signals; and

a control computer responsive to said reflected radar signals to track at least one object external to said vehicle, said control computer normalizing corresponding tracking amplitudes of said reflected radar signals to a predefined tracking distance and filtering said normalized tracking amplitudes to produce a smoothed tracking amplitude, said control computer setting a first radar blockage flag if said smoothed tracking amplitude drops below an amplitude threshold value.

10. The system of claim 9 wherein said control computer is operable to determine that said antenna is at least partially blocked if said first radar blockage flag is set.

11. The system of claim 9 further including a speed sensor producing a speed signal indicative of a travelling speed of said vehicle;

wherein said a control computer is operable to transform at least some of said reflected radar signals to relative radar power signals as a function of frequency, said control computer responsive to said speed signal to determine a mainbeam clutter peak of said relative radar power signal along a number of Doppler frequencies defined by said travelling speed, said control computer setting a second radar blockage flag if said mainbeam clutter peak is below a power threshold value.

12. The system of claim 11 wherein said at least some of said reflected radar signals correspond to continuous wave radar signals.

13. The system of claim 11 wherein said control computer is operable to determine a radar blockage state associated with said antenna as a function of said first and second radar blockage flags.

14. The system of claim 13 wherein said control computer is operable to determine that said antenna is at least partially blocked if either of said first and second radar blockages flags is set.

15. A method for detecting radar blockage, comprising the steps of:

transmitting a radar signal with a radar system carried by a motor vehicle;

receiving reflected radar signals resulting from said transmitting step;

processing said reflected radar signals to produce a relative power signal as a function of frequency;

determining a mainbeam clutter peak of said relative power signal based on a number of frequencies corresponding to those about a travelling speed of said vehicle; and

setting a first radar blockage flag if said mainbeam clutter peak is below a power threshold value.

16. The method of claim 15 further including the steps of:

processing said reflected radar signals to track at least one object external to said vehicle;

normalizing corresponding tracking amplitudes of said reflected radar signals to a predefined tracking distance;

filtering said normalized tracking amplitudes to produce a smoothed tracking amplitude; and

setting a second radar blockage flag if at least said smoothed tracking amplitude drops below an amplitude threshold value.

17. The method of claim 16 further including the step of determining a blockage state of said radar system as a function of said first and second radar blockage flags.

18. A method for detecting radar blockage, comprising the steps of:

transmitting a radar signal with a radar system carried by a motor vehicle;

receiving reflected radar signals resulting from said transmitting step;

processing said reflected radar signals to track at least one object external to said vehicle;

normalizing corresponding tracking amplitudes of said reflected radar signals to a predefined tracking distance;

filtering said normalized tracking amplitudes to produce a smoothed tracking amplitude; and

setting a first radar blockage flag if at least said smoothed tracking amplitude drops below an amplitude threshold value.

19. The method of claim 18 further including the steps of:

processing said reflected radar signals to produce a relative power signal as a function of frequency;

determining a mainbeam clutter peak of said relative power signal based on frequencies corresponding to those about a travelling speed of said vehicle; and

setting a second radar blockage flag if said mainbeam clutter peak is below a power threshold value.

20. The method of claim 19 further including the step of determining a blockage state of said radar system as a function of said first and second radar blockage flags.