Radar sensing of vehicle occupancy

• US 9,671,492 B2
• Filed: 08/13/2014
• Issued: 06/06/2017
• Est. Priority Date: 08/14/2013
• Status: Active Grant

• Current Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Original Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Inventors: Diewald, Andreas
• Primary Examiner(s): Barker, Matthew M
• Application Number:
  US14/912,379
• Publication Number:
  US 20160200276A1
• Time in Patent Office: 1,028 Days
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/6893 Cars
• CPC Class Codes: B60R 21/015 including means for detecting the presence or position of passengers, passenger seats or child seats , and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 7/354 Extracting wanted echo-signals Doppler systems G01S13/50
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

A method for sensing occupancy status within an automotive vehicle uses a radar sensor system, the radar sensor system includes an antenna system, at least one sensor and processing circuitry. The method comprises illuminating, using the antenna system, at least one occupiable position within the vehicle with continuous wave (CW signals), the CW signals being frequency modulated in time. At least one sensor signal (y(t,f₁ . . . y(t,f_n)) reflected as a result of the CW signals, is received using at least one sensor the at least one sensor defining a plurality of receive channels (1 . . . i), each channel having a different frequency (f₁ . . . f_i). Processing circuitry is operable for applying, for each receive channel (1 . . . i), DC offset removal to the corresponding sensor signal (y(t,f₁ . . . y(t,f_n)) to generate a modified signal (y′(t, f₁) . . . y′(t,f_n)); and generating, based on the modified signals (y′(t, f₁) . . . y′(t,f_n)) one or more occupancy status signals, the occupancy status signal indicating a property related to said at least one occupiable position.

Claims

1. A method for sensing occupancy status within an automotive vehicle using a radar sensor system, the radar sensor system comprising an antenna system, at least one sensor and processing circuitry, the method comprising:

illuminating, using the antenna system, at least one occupiable position within the vehicle with continuous wave (CW) signals, the CW signals being frequency modulated in time;

receiving, using the at least one sensor, at least one sensor signal reflected as a result of the CW signals, the at least one sensor including a plurality of receive channels, each channel having a different frequency;

applying, using the processing circuitry, for each receive channel, DC offset removal to the corresponding sensor signal to generate a modified signal; and

generating, using the processing circuitry, based on the modified signals, one or more occupancy status signals, the occupancy status signal indicating a property related to said at least one occupiable position.

2. The method of claim 1, wherein the one or more occupancy status signals comprise at least one of:

an occupant detection signal, indicating whether or not an occupant is present in the occupiable position,

an occupant classification signal, indicating a classification for an occupant present in the occupiable position, or

an occupant vital signs signal, indicating the extent to which vital signs are exhibited by an occupant in the occupiable position.

3. The method of claim 1, further comprising generating, using the processing circuitry, a composite signal based on the sensor signals from all receive channels.

4. The method of claim 3, further comprising generating, using the processing circuitry, a plurality of first intermediate signals in the time domain from the composite signal, each first intermediate signal corresponding to a candidate object.

5. The method of claim 4, further comprising performing, using the processing circuitry, object separation and exterior object subtraction on said composite signal to separate and eliminate objects that are external to the vehicle.

6. The method of claim 5, further comprising performing, using the processing circuitry, for each channel, a circle estimation operation on a signal comprising or based upon a respective sensor signal and outputting second intermediate signals.

7. The method of claim 6, further comprising performing, using the processing circuitry, the circle estimation before said DC offset removal, whereby said circle estimation operation is performed on a respective sensor signal, or performing said DC offset removal before the circle estimation, whereby said circle estimation operation is performed on a respective modified signal.

8. The method of claim 6, further comprising receiving, using the processing circuitry, said second intermediate signals and deriving therefrom, the average over N receive channels of a radius value of the circle estimation for the receive channels, and output third intermediate signals.

9. The method of claim 4, further comprising receiving, using the processing circuitry, the first intermediate signals or for receiving third intermediate signals and generating therefrom, the one or more occupancy status signals.

10. The method of claim 9, wherein:

(a) said occupancy status signal comprises an occupant detection signal; and

the method comprises operating the processing circuitry to generate;

(i) an occupant detection signal dependent upon a magnitude component of the first intermediate signals,

(ii) a positive occupant detection signal when a sum of vectors derived from the magnitude component of the first intermediate signals is greater than a minimum threshold, or

(iii) a negative occupant detection signal when a sum of vectors derived from the magnitude component of the first intermediate signals is less than a maximum threshold,

(b) said occupancy status signal comprises a vital signs signal; and

the method comprises operating the processing circuitry to generate the vital signs signal dependent upon a time-varying component of the first intermediate signals.

11. The method of claim 1, comprising applying, using the processing circuitry, a buffer strategy to the modified signals, or signals based thereon, to stabilize the one or more occupancy status signals wherein the buffer strategy implements a hysteresis using a two value threshold.

12. A programmable radar sensor system for sensing an occupancy status within an automotive vehicle, the radar sensor system comprising:

an antenna system configured to illuminate at least one occupiable position within the vehicle with continuous wave (CW) signals, the CW signals being frequency modulated in time;

at least one sensor configured to receive at least one sensor signal reflected as a result of the CW signals, the at least one sensor including a plurality of receive channels, each channel having a different frequency; and

processing circuitry configured to;

apply for each receive channel, DC offset removal to the corresponding sensor signal to generate a modified signal; and

generate based on the modified signals, one or more occupancy status signals that indicate a property related to said at least one occupiable position.

13. A radar sensor system for sensing occupancy status within an automotive vehicle, the system comprising:

an antenna system, for illuminating at least one occupiable position within the vehicle with continuous wave (CW) signals, the CW signals being frequency modulated in time;

at least one sensor for receiving at least one sensor signal reflected as a result of the CW signals, the at least one sensor including a plurality of receive channels, each channel having a different frequency;

processing circuitry, coupled to the at least one sensor, the processing circuitry being configured to;

apply, for each receive channel, DC offset removal to the corresponding sensor signal to generate a modified signal; and

generate, based on the modified signals, one or more occupancy status signals, the occupancy status signal indicating a property related to said at least one occupiable position.

14. A non-transitory computer readable medium having instructions stored thereon which, when executed, cause processing circuitry to:

receive, using at least one sensor, at least one radar sensor signal reflected as a result of continuous wave signals from an antenna system configured to illuminate at least one occupiable position within a vehicle, the continuous wave signals being frequency modulated in time, wherein the at least one sensor includes a plurality of receive channels, each channel having a different frequency;

apply, for each receive channel, a DC offset removal to the at least one radar sensor signal to generate a modified signal; and

generate, based on the modified signals, one or more occupancy status signals that indicate a property related to said at least one occupiable position.