In-vehicle human body detecting method

• US 20050122222A1
• Filed: 07/24/2003
• Published: 06/09/2005
• Est. Priority Date: 07/29/2002
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Takasuka, Hirofumi
• Granted Patent: US 7,276,030 B2
• Time in Patent Office: Days
• US Class Current: 340/573.100
• CPC Class Codes: B60R 21/01512 Passenger detection systems
• CPC Class Codes: B60R 21/0152 using strain gauges
• CPC Class Codes: B60R 21/01526 using piezoelectric elements
• CPC Class Codes: B60R 21/01552 detecting position of specific human body parts, e.g. face, eyes or hands
• CPC Class Codes: G01V 9/00 Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00

Abstract

Chest motion associated with breathing is detected to obtain a breathing motion signal representing the chest motion in the form of an electrical signal; then, the times at which specific points occur in the waveform of the breathing motion signal are detected and, when the time interval between the specific points is within a predetermined range, the presence of a human body is detected in a vehicle.

Claims

1. A human body detection method for detecting a human body in a vehicle, comprising:

detecting chest motion associated with breathing and obtaining a breathing motion signal representing said chest motion in the form of an electrical signal;

detecting times at which specific points occur in a waveform of said breathing motion signal; and

detecting the presence of a human body in said vehicle when time interval between said specific points is within a predetermined range.

2. A human body detection method as claimed in claim 1, wherein said specific points in the waveform of said breathing motion signal are peaks on a positive or negative side of the waveform of said breathing motion signal, and wherein the times (T(n)) at which said peaks occur are detected to obtain a peak-to-peak time interval (Δ

T(n)), a difference (Δ

t(n)) between peak-to-peak time intervals is obtained from said peak-to-peak time interval (Δ

T(n)), and the presence of a human body is detected in said vehicle when the difference (Δ

t(n)) between said peak-to-peak time intervals is smaller than a predetermined value (Tth).

3. A human body detection method as claimed in claim 2, wherein the number of times that the difference (Δ

t(n)) between said peak-to-peak time intervals is smaller than said predetermined value (Tth) is counted by a counter and, when the number of times counted is larger than a predetermined number (Cth), the presence of a human body is detected in said vehicle.

4. A human body detection method as claimed in claim 3, wherein said counter is reset when said peaks are not larger in magnitude than a predetermined level (Vth1).

5. A human body detection method as claimed in claim 2 wherein, when the difference (Δ

t(n)) between said peak-to-peak time intervals is smaller than said predetermined value (Tth), and when said peaks are larger in magnitude than a predetermined level (Vth2), the presence of a human body is detected in said vehicle.

6. A human body detection method as claimed in claim 3 wherein, when the number of times counted is larger than said predetermined number (Cth), and when said peaks are larger in magnitude than a predetermined level (Vth2), the presence of a human body is detected in said vehicle.

7. A human body detection method as claimed in claim 4 wherein, when said counter is not reset, and the number of times counted is larger than said predetermined number (Cth), and when said peaks are larger in magnitude than a predetermined level (Vth2), the presence of a human body is detected in said vehicle.

8. A human body detection method as claimed in claim 2 wherein, when two conditions, one being that the difference (Δ

t(n)) between said peak-to-peak time intervals is smaller than said predetermined value (Tth) and the other being that said peaks are larger in magnitude than a predetermined level (Vth1), are satisfied (CONDITION

     1), and when the condition that said peaks are larger in magnitude than a predetermined level (Vth2) is satisfied (CONDITION

     2), the presence of a human body is detected in said vehicle.

9. A human body detection method as claimed in claim 2 wherein, when two conditions, one being that the difference (Δ

t(n)) between said peak-to-peak time intervals is smaller than said predetermined value (Tth) and the other being that said peaks are larger in magnitude than a predetermined level (Vth1), are satisfied on both the positive and negative sides of said waveform (CONDITION

     1), and when the condition that said peaks are larger in magnitude than a predetermined level (Vth2) is satisfied (CONDITION

     2), the presence of a human body is detected in said vehicle.

10. A human body detection method as claimed in claim 8 wherein, when said CONDITION 1 and said CONDITION 2 are respectively satisfied a predetermined number of times, outputs thereof are held, and an AND circuit produces an output to detect the presence of a human body in said vehicle.

11. A human body detection method as claimed in claim 9 wherein, when said CONDITION 1 and said CONDITION 2 are respectively satisfied a predetermined number of times, outputs thereof are held, and AND circuits produces outputs, which are held and are input to an AND circuit that follows said AND circuits, and when conditions for said AND circuit are satisfied on both said positive and negative sides, the presence of a human body is detected in said vehicle.

12. A human body detection method as claimed in claim 2 wherein, when said peak-to-peak time interval (Δ

T(n)) is within a predetermined time interval range, the presence of a human body is detected in said vehicle.

13. A human body detection method as claimed in claim 1, wherein said specific points in the waveform of said breathing motion signal are rising or falling points of the waveform of said breathing motion signal, and wherein the times (Tu(n)) at which said rising or falling points occur are detected to obtain a time interval (Δ

Tu(n)) between said rising or falling points, a difference (Δ

tu(n)) between time intervals is obtained from said time interval (Δ

Tu(n)), the number of times that the difference (Δ

tu(n)) between said time intervals is smaller than a predetermined value (Tuth) is counted by a counter, and when the number of times counted is larger than a predetermined number (Cth), the presence of a human body is detected in said vehicle.

14. A human body detection method as claimed in claim 1, wherein said specific points in the waveform of said breathing motion signal are points defining a waveform width of said breathing motion signal, and wherein time interval (Δ

Tud(n)) of said waveform width is detected, a difference (Δ

tud(n)) between waveform width time intervals is obtained from said waveform width time interval (Δ

Tud(n)), the number of times that the difference (Δ

tud(n)) between said waveform width time intervals is smaller than a predetermined value (Tudth) is counted by a counter, and when the number of times counted is larger than a predetermined number (Cth), the presence of a human body is detected in said vehicle.

15. A human body detection method as claimed in claim 1, wherein said specific points in the waveform of said breathing motion signal are positive and negative peaks of the waveform of said breathing motion signal, and wherein the times at which said positive and negative peaks occur are detected, the ratio of the time interval from said positive peak to said negative peak or from said negative peak to said positive peak to the time interval from said positive peak to the next positive peak is obtained, the number of times that said ratio is within a predetermined range is counted by a counter, and when the number of times counted is larger than a predetermined number (Cth), the presence of a human body is detected in said vehicle.

16. A human body detection method as claimed in claim 15, wherein the ratio of the time interval from said positive peak to said negative peak or from said negative peak to said positive peak to the time interval from said negative peak to the next negative peak is obtained, the number of times that said ratio is within said predetermined range is counted by said counter, and when the number of times counted is larger than said predetermined number (Cth), the presence of a human body is detected in said vehicle.

17. A human body detection method as claimed in claim 15 wherein, when the number of times that said ratio is within said predetermined range, counted by said counter, is larger than said predetermined number (Cth), and when the difference (Δ

t(n)) between said peak-to-peak time intervals in the waveform of said breathing motion signal is smaller than a predetermined value (Tth), the presence of a human body is detected in said vehicle.

18. A human body detection method as claimed in claim 15 wherein, when the number of times that said ratio is within said predetermined range, counted by said counter, is larger than said predetermined number (Cth), and when the number of times that the difference (Δ

t(n)) between said peak-to-peak time intervals in the waveform of said breathing motion signal is smaller than said predetermined value (Tth), counted by said counter, is larger than said predetermined number (Cth), the presence of a human body is detected in said vehicle.

19. A human body detection apparatus comprising:

means for detecting chest motion associated with breathing and obtaining a breathing motion signal representing said chest motion in the form of an electrical signal;

means for detecting times at which specific points occur in a waveform of said breathing motion signal; and

means for detecting the presence of a human body in a vehicle when time interval between said specific points is within a predetermined range.

20. A vehicle providing a human body detection apparatus comprising:

means for detecting chest motion associated with breathing and obtaining a breathing motion signal representing said chest motion in the form of an electrical signal;

means for detecting times at which specific points occur in a waveform of said breathing motion signal; and

means for detecting the presence of a human body in a vehicle when time interval between said specific points is within a predetermined range.