# US 10,119,986 B2 · Time and frequency domain based step counter

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- Number: US 10,119,986 B2
- Document ID: US10119986B2
- Status: Granted
- Kind: B2
- Application number: 14/722,319
- Filed: 2015-05-27
- Published: 2018-07-19
- Granted: 2018-11-06
- Earliest claimed: 2014-04-29
- Assignees: NXP B.V.
- Applicants: NXP B.V.
- Inventors: Vasanth Gaddam; Yifeng Zhang; Jie Zhang; Yuanwei Wu; Guanqing Wang
- Web page: https://patentgrep.com/patent/US10119986B2

## CPC

- A61B 5/1118: {Determining activity level}
- A61B 5/1123: {Discriminating type of movement, e.g. walking or running (A61B5/1116, A61B5/112 take precedence)}
- A61B 5/725: {using specific filters therefor, e.g. Kalman or adaptive filters (specific diagnostics methods using using bioelectric or biomagnetic signals A61B5/316)}
- A61B 5/7264: {Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems}
- G01C 21/20: Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence)
- G01C 22/006: {Pedometers}
- G01P 15/00: Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 30/6211: {having fin-shaped semiconductor bodies integral with the bulk semiconductor substrates}
- H10D 64/015: {removing at least parts of gate spacers, e.g. disposable spacers}
- H10D 64/017: {using dummy gates in processes wherein at least parts of the final gates are self-aligned to the dummy gates, i.e. replacement gate processes}
- H10D 64/021: {using multiple gate spacer layers, e.g. bilayered sidewall spacers}
- H10P 50/71: {using masks for conductive or resistive materials}
- G16H 50/20: for computer-aided diagnosis, e.g. based on medical expert systems
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

A system for counting steps comprising a 3-D accelerometer is disclosed. The system also includes a pre-processor module coupled to the 3-D accelerometer and a dominant component computation unit coupled to the pre-processor module. The dominant component computation unit is configured to identify a dominant component in an output of the 3-D accelerometer. The system further includes a step counter for counting a number of steps using the output of the dominant component computation unit. The step counter includes a Fast Fourier Transform (FFT) module and a direct current (DC) remover module to remove a static component from the output of the FFT module. The step counter also includes a derivative filter and a zero crossing detector.

## Claims

### Claim 1

A system for counting steps, the system comprising:
a three-dimensional (3-D) accelerometer sensor-circuitry including sensor circuits configured and arranged to generate and output accelerometer data associated with three perpendicular axes;
pre-processor circuitry coupled to the 3-D accelerometer sensor-circuitry configured and arranged to produce filtered accelerometer data;
dominant component computation circuitry coupled to the pre-processor circuit, wherein the dominant component computation circuit is configured and arranged to identify a dominant component among vertical and horizontal component data in the output of the 3-D accelerometer sensor-circuitry; and
step counter circuitry configured and arranged to count a number of steps using the output of the dominant component computation circuit, wherein the step counter circuit includes a Fast Fourier Transform (FFT) circuit and a direct current (DC) remover circuit configured and arranged to remove a static component from an output of the FFT circuit, an activity frequency selector circuit, a derivative filter circuit and a zero crossing detector circuit.

### Claim 2 (depends on 1)

The system of claim 1, further comprising a statistics generator module, including circuitry, coupled to the dominant component computation circuitry and the pre-processor circuitry.

### Claim 3 (depends on 2)

The system of claim 2, further comprising a classifier, including circuitry, configured and arranged to determine an activity based on outputs of the dominant component computation circuitry and the statistics generator module.

### Claim 4 (depends on 3)

The system of claim 3, wherein the step counter circuitry is configured to refine an output of the step counter circuitry based on an output of the classifier.

### Claim 5 (depends on 1)

The system of claim 1, further including post-processor circuitry that is configured to refine an output of the step counter circuitry.

### Claim 6 (depends on 2)

The system of claim 2, wherein the statistics generator module includes a first statistics circuit and a second statistics circuit, wherein the first statistics circuit-is configured to generate statistics and frequency domain transformation based on an output of the dominant component computation circuitry and the second statistics circuit is configured to generate statistics and frequency domain transformation based on an output of the pre-processor circuitry.

### Claim 7 (depends on 1)

The system of claim 1, wherein the pre-processor circuitry is configured to remove at least one of a direct current (DC) component in a vector sample received from the 3-D accelerometer sensor-circuitry and a high frequency component from the vector sample.

### Claim 8 (depends on 7)

The system of claim 7, wherein the dominant component computation circuitry is configured to determine a dominant component in the vector sample.

### Claim 9 (depends on 8)

The system of claim 8, wherein the vector sample includes the horizontal component data and the vertical component data.

### Claim 10 (depends on 9)

The system of claim 9, wherein the vertical component data is proportional to a vector inner product between a mean vector of a plurality of vector samples along three axes and each dynamic vector corresponding to a first difference between each of the plurality of vector samples and the mean vector.

### Claim 11 (depends on 10)

The system of claim 10, wherein the horizontal component data is related to a norm of a second difference between the first difference and the mean vector scaled by the vertical component data.

### Claim 12 (depends on 1)

The system of claim 1, wherein the pre-processor circuitry includes at least one of a level normalization circuit, a DC notch filter circuit and a low pass filter circuit.

### Claim 13 (depends on 1)

The system of claim 1, further including an activity classifier circuit, wherein the activity classifier circuit is configured and arranged to refine an output of the step counter circuitry.

### Claim 14 (depends on 13)

The system of claim 13, wherein the activity classifier circuit is embodied in an external device that is configured and arranged to communicate with the step counter circuitry.

### Claim 15

A non-transitory computer readable medium having programming instructions stored thereon which, when executed by a processor, cause the processor to perform a method including:
receiving an output from three-dimensional (3-D) accelerometer sensor-circuitry, including sensor circuits, configured and arranged to generate and output accelerometer data associated with three perpendicular axes;
pre-processing the received output of the 3-D accelerometer sensor-circuitry, wherein the pre-processing includes removing a direct current (DC) component from the output of the 3-D accelerometer sensor-circuitry;
determining a dominant component among vertical component data and horizontal component data in the output of the 3-D accelerometer sensor-circuitry after the pre-processing, wherein the output of the 3-D accelerometer sensor-circuitry is used to derive the vertical component data and the horizontal component data, the vertical component data is proportional to a vector inner product between a mean vector of a plurality of vector samples along the three perpendicular axes and each dynamic vector corresponding to a first difference between each of the plurality of vector samples and the mean vector, wherein the horizontal component data is related to a norm of a second difference between the first difference and the mean vector scaled by the vertical component data; and
counting steps using the dominant component, wherein the counting includes performing a Fast Fourier Transform (FFT) and zero crossing detection.

### Claim 16 (depends on 15)

The computer readable medium of claim 15, further including programming instructions, which when executed by the processor, cause the processor to collect statistical data based on at least one of a time domain data and frequency domain data derived from the accelerometer data or the dominant component, and determining an activity type.

### Claim 17 (depends on 16)

The-computer readable medium of claim 16, wherein the counting is refined to remove false steps using the activity type.

### Claim 18 (depends on 15)

The computer readable media of claim 15, wherein the operation further includes removing a high frequency component from the vector sample.

### Claim 19 (depends on 15)

The computer readable medium of claim 15, wherein determining the dominant component includes determining in a vector sample in the plurality of vector samples, wherein the vector sample includes the horizontal component data and the vertical component.

### Claim 20 (depends on 19)

The computer readable medium of claim 19, wherein the vertical component data is proportional to a vector inner product between a mean vector of a plurality of vector samples along three axes and each dynamic vector corresponding to a first difference between each of the plurality of vector samples and the mean vector.