Method and system for heterogeneous event detection
A method and system for heterogeneous event detection. Sensor data is obtained and divided into discrete data windows. Each data window is defined by and corresponds to a time period of the sensor data. A time-frequency representation over the time period is calculated for each data window. A filter mask is calculated based on the data window corresponding to the time-frequency representation. The filter mask is applied for reverting the time-frequency representation to a time representation, resulting in filtered data. Features, such as extrema or other inflection points, are identified in the filtered data. The features define events, and transforming the time-frequency representation back into the time domain emphasizes differences between more and less prominent frequencies, facilitating identification of heterogeneous events. The method and system may be applied to body movements of people or animals, automaton movement, audio signals, light intensity, or any suitable time-dependent variable.
1. A method for detecting heterogeneous events comprising:
receiving pressure sensor data;
defining a data window over a time period of the pressure sensor data;
calculating a time-frequency representation of the data window for providing the time-frequency representation corresponding to the time period;
calculating a filter mask based on the time-frequency representation, wherein the filter mask comprises non-binary values proportional to a positive exponent of a magnitude of a time-frequency transform, wherein more prominent frequencies will be emphasized, and less prominent frequencies will be de-emphasized;
filtering the time-frequency representation with the filter mask, providing filtered data;
identifying features in the filtered data;
identifying a body movement event with reference to the features; and
outputting the body movement event.
2. The method of claim 1 wherein the pressure sensor data comprises at least two different types of data.
3. The method of claim 1 wherein the method further comprises receiving data of acceleration, rotation, seismic changes, temperature, humidity, and/or sound.
4. The method of claim 1 wherein receiving the pressure sensor data is at a down-sampled rate to increase body movement event detection speed.
5. The method of claim 1 wherein the data window includes a first data window from which the pressure sensor data is received, and a second data window from which the filtered data is provided, and receiving the pressure sensor data of the first data window is at a rate determined with reference to the filtered data of the second data window, the second data window preceding the first data window in time.
6. The method of claim 1 wherein the time period of the data window has a duration equal to additional data windows preceding or succeeding the data window.
7. The method of claim 1 wherein calculating the time-frequency representation of the data window comprises applying an S-transform to the pressure sensor data within the data window.
8. The method of claim 1 wherein calculating the time-frequency representation of the data window comprises applying a Gabor transform to the pressure sensor data within the data window.
9. The method of claim 1 wherein filtering the time-frequency representation comprises normalizing all values in the time-frequency representation.
10. The method of claim 1 wherein the features comprise inflection points.
11. The method of claim 1 wherein identifying the body movement event comprises deriving an event count or defining the features as endpoints of the body movement event.
12. The method of claim 11 wherein identifying the body movement event comprises characterizing the pressure sensor data between time points corresponding to the endpoints defined in the filtered data.
13. The method of claim 1 wherein identifying the body movement event comprises defining a pulse width, a cycle, a ground contact time, a center of pressure, or a path of center of pressure of the pressure sensor data or the filtered data.
14. The method of claim 1 wherein outputting the body movement event comprises communicating data relating to the body movement event to an individual, prompting the individual to change a health-based behavior with event feedback, storing data relating to the body movement event in a computer readable medium, or outputting contribution to the pressure sensor data from each of a plurality of sensors.
15. A system for detecting heterogeneous events comprising:
a sensor for receiving sensor data; and
a processor in communication with the sensor for receiving the sensor data;
wherein the processor is configured to execute instructions for carrying out the method of claim 1 .
16. The system of claim 15 wherein the processor is configured for localized filtering of the time-frequency representation based on the filter mask by applying an S-transform to the sensor data.
17. The system of claim 15 wherein the sensor comprises a pressure sensor and one or more of a gyroscope, an accelerometer, a seismograph, a thermometer, or a humidity sensor.
18. The system of claim 15 wherein the sensor is configured to monitor activities, movements, and functions of a wearer of the sensor.
19. The system of claim 15 wherein the sensors are mounted on a shoe insert.