Motion detection based on filtered statistical parameters of wireless signals

• US 10,228,439 B1
• Filed: 10/31/2017
• Issued: 03/12/2019
• Est. Priority Date: 10/31/2017
• Status: Active Grant

• Current Assignee: Cognitive Systems Corp.
• Original Assignee: Cognitive Systems Corp.
• Inventors: Olekas, Christopher Vytautas, Piao, Yunfeng, Devison, Stephen Arnold
• Primary Examiner(s): Nguyen, Chuong P
• Application Number:
  US15/799,806
• Time in Patent Office: 497 Days
• Field of Search: 342451, 34235751
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• 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 13/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 19/13 Receivers
• CPC Class Codes: G01S 5/0278 involving statistical or probabilistic considerations G01S5/0252, G01S5/0294 take precedence
• CPC Class Codes: G06F 17/142 Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm
• CPC Class Codes: G06F 17/18 for evaluating statistical data , e.g. average values, frequency distributions, probability functions, regression analysis forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04
• CPC Class Codes: G08B 13/2491 Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field

Abstract

In a general aspect, motion is detected based on statistical parameters of received wireless signals. In some aspects, signals are obtained. The signals are based on wireless signals transmitted through a space and received at a wireless communication device. Values of a set of statistical parameters are computed for each signal, and filtered values are obtained by applying a filter to the values of the statistical parameters. The filter includes parameters based on a signal quality analysis of the wireless signals. A motion detection process is executed to determine, based on the filtered values, whether an object moved in the space.

Claims

1. A motion detection method comprising:

obtaining signals based on wireless signals transmitted through a space and received at a wireless communication device;

computing, for each signal, values of a set of statistical parameters;

obtaining filtered values by applying a filter to the values of the statistical parameters, the filter comprising parameters based on a signal quality analysis of the wireless signals; and

by operation of one or more processors, executing a motion detection process to determine motion detection data, based on the filtered values, indicating whether an object moved in the space; and

communicating the motion detection data to a device for monitoring movement within the space.

2. The method of claim 1, wherein applying the filter comprises:

computing scaling factors based on the signal quality analysis; and

generating the filtered values by applying the scaling factors to the values of the statistical parameters.

3. The method of claim 2, comprising computing values of a signal quality metric for the respective wireless signals, and computing each scaling factor based on the signal quality metric values.

4. The method of claim 3, wherein each scaling factor is based on a ratio of the value of the signal quality metric to a target signal quality metric value.

5. The method of claim 3, comprising computing each scaling factor further based on an amount of time needed to obtain a sufficient number of the wireless signals for inputs to the motion detection process based on values of the signal quality metric.

6. The method of claim 5, wherein each scaling factor is based on a ratio of a target amount of time to the amount of time needed to obtain a sufficient number of signals for inputs to the motion detection process.

7. The method of claim 1, wherein the set of statistical parameters includes a first statistical parameter and a second statistical parameter, the first statistical parameter based on a first function applied to frequency components of the signals, the second statistical parameter based on a second function applied to frequency components of the signals.

8. The method of claim 7, wherein the first statistical parameter is the mean and the second statistical parameter is the standard deviation.

9. The method of claim 1, comprising:

obtaining a frequency-domain representation of the wireless signals received by the wireless communication device; and

generating the signals based on a subset of frequency components in the frequency-domain representation.

10. The method of claim 1, comprising generating histogram data from the filtered values, the histogram data comprising a set of bins and a quantity for each bin, each bin corresponding to a respective range for each of the statistical parameters, wherein the motion detection process uses the histogram data to determine whether an object moved.

11. The method of claim 10, wherein the histogram data corresponds to a multi-dimensional histogram, and executing the motion detection process comprises determining sums of the quantities along each dimension of the histogram, computing check values based on the sums, and comparing the check values with respective thresholds.

12. The method of claim 11, wherein executing the motion detection process comprises computing motion signature values based on a set of the check values, and comparing motion signature values for respective time periods.

13. The method of claim 10, wherein generating the histogram data from the filtered values comprises renormalizing the filtered values.

14. A motion detection system comprising:

a data processing apparatus; and

memory comprising instructions that are operable when executed by the data processing apparatus to perform operations comprising;

obtaining signals based on wireless signals transmitted through a space and received at a wireless communication device;

computing, for each signal, values of a set of statistical parameters;

obtaining filtered values by applying a filter to the values of the statistical parameters, the filter comprising parameters based on a signal quality analysis of the wireless signals; and

executing a motion detection process to determine motion detection data, based on the filtered values, indicating whether an object moved in the space; and

communicating the motion detection data to a device for monitoring movement within the space.

15. The motion detection system of claim 14, wherein applying the filter comprises:

computing scaling factors based on the signal quality analysis; and

generating the filtered values by applying the scaling factors to the values of the statistical parameters.

16. The motion detection system of claim 15, comprising computing values of a signal quality metric for the respective wireless signals, and computing each scaling factor based on the signal quality metric values.

17. The motion detection system of claim 16, wherein each scaling factor is based on a ratio of the value of the signal quality metric to a target signal quality metric value.

18. The motion detection system of claim 16, comprising computing each scaling factor further based on an amount of time needed to obtain a sufficient number of the wireless signals for inputs to the motion detection process based on values of the signal quality metric.

19. The motion detection system of claim 18, wherein each scaling factor is based on a ratio of a target amount of time to the amount of time needed to obtain a sufficient number of signals for inputs to the motion detection process.

20. The motion detection system of claim 14, wherein the set of statistical parameters includes a first statistical parameter and a second statistical parameter, the first statistical parameter based on a first function applied to frequency components of the signals, the second statistical parameter based on a second function applied to frequency components of the signals.

21. The motion detection system of claim 20, wherein the first statistical parameter is the mean and the second statistical parameter is the standard deviation.

22. The motion detection system of claim 14, comprising:

obtaining a frequency-domain representation of the wireless signals received by the wireless communication device; and

generating the signals based on a subset of frequency components in the frequency-domain representation.

23. The motion detection system of claim 14, comprising generating histogram data from the filtered values, the histogram data comprising a set of bins and a quantity for each bin, each bin corresponding to a respective range for each of the statistical parameters, wherein the motion detection process uses the histogram data to determine whether an object moved.

24. The motion detection system of claim 23, wherein the histogram data corresponds to a multi-dimensional histogram, and executing the motion detection process comprises determining sums of the quantities along each dimension of the histogram, computing check values based on the sums, and comparing the check values with respective thresholds.

25. The motion detection system of claim 24, wherein executing the motion detection process comprises computing motion signature values based on a set of the check values, and comparing motion signature values for respective time periods.

26. The motion detection system of claim 23, wherein generating the histogram data from the filtered values comprises renormalizing the filtered values.

27. A computer-readable storage medium storing instructions that are operable when executed by a data processing apparatus to perform operations comprising:

obtaining signals based on wireless signals transmitted through a space and received at a wireless communication device;

computing, for each signal, values of a set of statistical parameters;

obtaining filtered values by applying a filter to the values of the statistical parameters, the filter comprising parameters based on a signal quality analysis of the wireless signals; and

executing a motion detection process to determine motion detection data, based on the filtered values, indicating whether an object moved in the space; and

communicating the motion detection data to a device for monitoring movement within the space.

28. The computer-readable storage medium of claim 27, wherein applying the filter comprises:

computing scaling factors based on the signal quality analysis; and

generating the filtered values by applying the scaling factors to the values of the statistical parameters.

29. The computer-readable storage medium of claim 27, comprising computing values of a signal quality metric for the respective wireless signals, and computing each scaling factor based on the signal quality metric values.

30. The computer-readable storage medium of claim 29, comprising computing each scaling factor further based on an amount of time needed to obtain a sufficient number of the wireless signals for inputs to the motion detection process based on values of the signal quality metric.