Method and apparatus for determining the presence and/or absence and/or a characteristic of an object on a support

• US 20030109993A1
• Filed: 12/31/2002
• Published: 06/12/2003
• Est. Priority Date: 07/03/2000
• Status: Abandoned Application

• Current Assignee: Med-Dev Limited
• Original Assignee: Med-Dev Limited
• Inventors: Littek, Arnim Holger, Peat, Donald
• Application Number:
  US10/312,839
• Publication Number:
  US 20030109993A1
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60R 21/01512 Passenger detection systems

Abstract

A method of determining the presence and/or absence and/or a characteristic of an object on a support (4). The method includes the steps of: a) acquiring a target signal indicative of vibration of the support at a first location; b) acquiring a reference signal, the reference signal being indicative of vibration of the support at a second location; c) calculating a ratio of the target signal and the reference signal; and d) determining the presence and/or absence and/or a characteristic of an object on the support in accordance with the ratio determined in step c).

Claims

1. A method of determining the presence and/or absence and/or a characteristic of an object on a support, the method including the steps of:

a) acquiring a target signal indicative of vibration of the support at a first location;

b) acquiring a reference signal indicative of vibration of the support at a second location;

c) calculating a ratio of the target signal and the reference signal; and

d) determining the presence and/or absence and/or a characteristic of an object on the support in accordance with the ratio determined in step c).

2. The method of claim 1, wherein the target signal is acquired in step a) by receiving a target vibration signal from a sensor mounted on the support at the first location and processing the target vibration signal to calculate a first signal characteristic which varies in accordance with the presence and/or absence and/or a characteristic of an object on the support;

and wherein the reference signal is acquired in step c) by receiving a reference vibration signal and processing the reference vibration signal to calculate a second signal characteristic; and

wherein step c) includes the step of calculating the ratio of the first and second signal characteristics.

3. The method of claim 2 wherein the first and second signal characteristics are indicative of an average power of vibration of the support at the first and second locations during a predetermined time period.

4. The method of claim 2 wherein the first and second signal characteristics are indicative of a power of vibration of the support at the first and second locations in a predetermined wavelength band.

5. The method of claim 4 wherein the signals are calculated by Fourier transforming the target and reference vibration signals.

6. The method of claim 2 wherein the first and second signal characteristics are correlation coefficients indicative of a degree of correlation between the vibration signals and a predetermined encoded sequence.

7. The method of claim 6 wherein the predetermined encoded sequence is a pseudo-random sequence.

8. The method of any of the preceding claims wherein the reference signal is acquired in step b) from a sensor mounted at the second location.

9. The method of any of the preceding claims further including the steps of generating the reference signal with a signal generator;

and inputting the reference signal to a source of mechanical vibration to vibrate the support at the second location in accordance with the reference signal.

10. The method of claim 9 wherein the signal generator inputs a predetermined encoded sequence into the source of mechanical vibration.

11. The method of claim 9 or 10 wherein the reference signal is acquired in step b) from the signal generator.

12. The method of any of the preceding claims wherein a plurality of ratio values are calculated in step c);

and wherein the presence and/or absence and/or weight of an object on the support is determined in step d) by performing a pattern recognition algorithm on the plurality of ratio values.

13. The method of claim 12 further including the step of training a pattern recognition network to perform the pattern recognition algorithm by inputting a plurality of sets of training data values into the pattern recognition network.

14. The method of any of the preceding claims wherein step d) includes the step of distinguishing between different categories of object.

15. The method of any of the preceding claims wherein the support is located in a vehicle.

16. The method of any of the preceding claims further including the steps of:

acquiring one or more additional target signals indicative of vibration of the support at one or more additional locations;

calculating one or more additional ratios using the additional target signal(s); and

determining the presence and/or absence and/or a characteristic of an object on the support in step d) in accordance with the additional ratio(s).

17. The method of any of the preceding claims wherein the object is a human or animal subject.

18. Apparatus for determining the presence and/or absence and/or a characteristic of an object on a support, the apparatus including:

a) means for acquiring a target signal indicative of vibration of the support at a first location;

b) means for acquiring a reference signal, the reference signal being indicative of vibration of the support at a second location;

c) means for calculating a ratio of the target signal and the reference signal; and

d) means for determining the presence and/or absence and/or a characteristic of an object on the support in accordance with the calculated ratio.

19. The apparatus of claim 18, wherein the means for acquiring a target signal comprises a target sensor for generating a target vibration signal and means for receiving and processing the target vibration signal to calculate a first signal characteristic which varies in accordance with the presence and/or absence and/or a characteristic of an object on the support;

and wherein the means for acquiring a reference signal receives a reference vibration signal and processes the reference vibration signal to calculate a second signal characteristic.

20. The apparatus of claim 19 wherein the first and second signal characteristics are indicative of an average power of vibration of the support at the first and second locations during a predetermined time period.

21. The apparatus of claim 19 wherein the signals are indicative of a power of vibration of the support at the first and second locations in a predetermined wavelength band.

22. The apparatus of claim 21 wherein the signals are calculated by Fourier transforming the target and reference vibration signals.

23. The apparatus of any of claims 18 to 22 wherein the means for acquiring a reference signal includes a sensor mounted at the second location.

24. The apparatus of any of claims 18 to 23 further including a source of mechanical vibration for vibrating the support at the second location;

and a signal generator for generating the reference signal and inputting the reference signal to the source of mechanical vibration.

25. The apparatus of claim 24 wherein the reference signal is acquired from the signal generator.

26. The apparatus of any of claims 18 to 25 wherein a plurality of ratio values are calculated;

and wherein the means for determining the presence and/or absence and/or a characteristic of an object on the support includes a pattern recognition engine for performing a pattern recognition algorithm on the plurality of ratio values.

27. The apparatus of claim 26 wherein the pattern recognition engine includes a pattern recognition network which has been trained to perform the pattern recognition algorithm by inputting a plurality of sets of training data values into the pattern recognition network.

28. The apparatus of any of claims 18 to 27 wherein the means for determining can distinguish between different categories of object.

29. The apparatus of any of claims 18 to 28 installed in a support which includes a compressible material between the first and second locations.

30. The apparatus of any of claims 18 to 29 installed in a support which is situated in a vehicle.

31. The apparatus of any of claims 18 to 30 including one or more additional target sensors for acquiring one or more additional target signals indicative of vibration of the support at one or more additional locations.

32. The apparatus of any of claims 18 to 31 including one or more additional reference sensors for acquiring one or more additional target signals indicative of vibration of the support at one or more additional locations.

33. The apparatus of any of claims 18 to 32 adapted to determine the presence and/or absence and/or a characteristic of a human or animal subject on the support.