Sensor-Based Athletic Activity Measurements

• US 20130006583A1
• Filed: 07/01/2011
• Published: 01/03/2013
• Est. Priority Date: 07/01/2011
• Status: Active Grant

• Current Assignee: Nike, Inc.
• Original Assignee: Nike, Inc.
• Inventors: Weast, Aaron B., Mullin, James M.
• Granted Patent: US 9,446,287 B2
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: A61B 2503/10 Athletes
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/112 Gait analysis
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence
• CPC Class Codes: A61B 5/6807 Footwear
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A63B 2024/0065 Evaluating the fitness, e.g. fitness level or fitness index
• CPC Class Codes: A63B 2220/20 Distances or displacements
• CPC Class Codes: A63B 2220/836 Sensors arranged on the body of the user
• CPC Class Codes: A63B 2230/75 calorie expenditure
• CPC Class Codes: A63B 24/0062 Monitoring athletic performances, e.g. for determining the work of a user on an exercise apparatus, the completed jogging or cycling distance

Abstract

Determining pace or speed based on sensor data may include determining an amount of contact time a user'"'"'s foot has with a workout surface such as the ground. Contact time may be determined by identifying samples in the sensor data that correspond to various events such as a heelstrike, a toe-off and a subsequent heelstrike. In one example, these events may be identified by determining a sequence of three sample values (e.g., a triplet) that exceeds corresponding thresholds. The validity of an identified triplet (e.g., heelstrike, toe-off and heelstrike) may be confirmed by determining whether a difference between a last event sample and a middle event sample is greater than a difference between the middle event sample and an initial event sample. Once confirmed, a contact time may be determined from the triplet. A linear or non-linear relationship may then be applied to the contact time to determine a speed or pace.

Claims

1. A method comprising:

determining a signal generated by a sensor during athletic activity performed by a user, wherein the signal comprises a plurality of samples;

processing the signal based on a moving standard deviation;

identifying a sequence of three samples in the processed signal that corresponds to a physical foot-step taken by the user, wherein the sequence of three samples includes an initial sample, a middle sample and a last sample; and

determining a pace of the user based on an elapsed time between at least two of the initial, middle and last samples.

2. The method of claim 1, further comprising:

determining a first difference between a value of the last sample and a value of the initial sample;

determining a second difference between a value of the middle sample and the value of the initial sample;

determining whether the first difference is greater than the second difference; and

in response to determining that the first difference is greater than the second difference, adding the sequence of three samples to a list.

3. The method of claim 2, further comprising:

adding a plurality of three sample sequences to the list; and

determining a plurality of contact times of the user based on the plurality of three sample sequences in the list.

4. The method of claim 3, further comprising:

determining a mean contact time of the plurality of contact times;

determining a standard deviation between the plurality of contact times; and

filtering out one or more contact times of the plurality of paces that exceed a threshold number of standard deviations from the mean contact time.

5. The method of claim 1, wherein determining the pace of the user based on an elapsed time between at least two of the initial, middle and last samples includes:

determining a contact time by determining a difference between the middle sample and the initial sample; and

applying a predefined linear relationship to the contact time to calculate the pace of the user.

6. The method of claim 5, further comprising selecting the predefined linear relationship from a plurality of linear relationships, wherein each of the plurality of linear relationships corresponds to a different type of athletic activity.

7. The method of claim 1, wherein identifying the sequence of three samples in the processed signal that corresponds to a physical foot-step taken by the user includes:

selecting a first sample from the plurality of samples;

determining whether a value of the first sample meets a first threshold sample value;

in response to determining that the value of the first sample does not meet the first threshold sample value, selecting a subsequent sample in the plurality of samples; and

in response to determining that the value of the first sample meets the first threshold sample value;

determining a maximum sample value in a first sample window of a predefined size, wherein a lower bound of the first sample window corresponds to the first sample, and

identifying a sample corresponding to the maximum sample value as the initial sample.

8. The method of claim 7, wherein in response to determining that the value of the first sample meets the threshold sample value, the method further comprises:

determining a maximum sample value in a second sample window; and

determining whether the maximum sample value of the second sample window meets a second threshold sample value; and

in response to determining that the maximum sample value of the second sample window meets the second threshold sample value, identifying a sample corresponding to the maximum sample value of the second sample window as the middle sample.

9. An apparatus comprising:

at least one processor; and

memory operatively coupled to the at least one processor and storing computer readable instructions that, when executed, cause the apparatus to;

determine a signal generated by a sensor during athletic activity performed by a user, wherein the signal comprises a plurality of samples;

process the signal based on a moving standard deviation;

identify a sequence of three samples in the processed signal that corresponds to a physical foot-step taken by the user, wherein the sequence of three samples includes an initial sample, a middle sample and a last sample; and

determine a pace of the user based on an elapsed time between at least two of the initial, middle and last samples.

10. The apparatus of claim 9, wherein the apparatus includes a sensor.

11. The apparatus of claim 9, wherein the apparatus further includes an interface configured to connect to a separate display device.

12. The apparatus of claim 9, wherein the computer readable instructions, when executed, further cause the apparatus to:

determine a first difference between a value of the last sample and a value of the initial sample;

determine a second difference between a value of the middle sample and the value of the initial sample;

determine whether the first difference is greater than the second difference; and

in response to determining that the first difference is greater than the second difference, adding the sequence of three samples to a list.

13. The apparatus of claim 12, wherein the computer readable instructions, when executed, further cause the apparatus to:

add a plurality of three sample sequences to the list; and

determine a plurality of contact times of the user based on the plurality of three sample sequences in the list.

14. The apparatus of claim 13, wherein the computer readable instructions, when executed, further cause the apparatus to:

determine a mean contact time of the plurality of contact times;

determine a standard deviation between the plurality of contact times; and

filter out one or more contact times of the plurality of contact times that exceed a threshold number of standard deviations from the mean contact time.

15. One or more non-transitory computer readable media storing computer readable instructions that, when executed, cause an apparatus to:

determine a signal generated by a sensor during athletic activity performed by a user, wherein the signal comprises a plurality of samples;

process the signal based on a moving standard deviation;

identify a sequence of three samples in the processed signal that corresponds to a physical foot-step taken by the user, wherein the sequence of three samples includes an initial sample, a middle sample and a last sample; and

determine a pace of the user based on an elapsed time between at least two of the initial, middle and last samples.

16. The one or more computer readable media of claim 15, wherein determining the pace of the user based on an elapsed time between at least two of the initial, middle and last samples includes:

determining a contact time by determining a difference between the middle sample and the initial sample; and

applying a predefined linear relationship to the contact time to calculate the pace of the user.

17. The one or more computer readable media of claim 16, further comprising computer readable instructions that, when executed, cause the apparatus to select the predefined linear relationship from a plurality of linear relationships, wherein each of the plurality of linear relationships corresponds to a different type of athletic activity.

18. The one or more computer readable media of claim 15, wherein identifying the sequence of three samples in the processed signal that corresponds a physical foot-step taken by the user includes:

selecting a first sample from the plurality of samples;

determining whether a value of the first sample meets a first threshold sample value;

in response to determining that the value of the first sample does not meet the first threshold sample value, selecting a subsequent sample in the plurality of samples; and

in response to determining that the value of the first sample meets the first threshold sample value;

determining a maximum sample value in a first sample window of a predefined size, wherein a lower bound of the first sample window corresponds to the first sample, and

identifying a sample corresponding to the maximum sample value as the initial sample.

19. The one or more computer readable media of claim 15, further comprising computer readable instructions that, when executed, cause the apparatus to:

determine a first difference between a value of the last sample and a value of the initial sample;

determine a second difference between a value of the middle sample and the value of the initial sample;

determine whether the first difference is greater than the second difference; and

in response to determining that the first difference is greater than the second difference, add the sequence of three samples to a list.

20. The one or more computer readable media of claim 19, further comprising computer readable instructions that, when executed, cause the apparatus to:

add a plurality of three sample sequences to the list; and

determine a plurality of contact times of the user based on the plurality of three sample sequences in the list.