KR20170111408A - Apparatus and method for step calculation - Google Patents

Abstract

The present invention suggests an apparatus and method for measuring the number of steps.
The apparatus for measuring the number of steps according to the present invention includes an acceleration sensor for measuring a gravity direction acceleration value and a variation amount of the acceleration value generated when a user is walking, a gyro sensor used for grasping the position of the user, and an MCU, And a controller for determining whether the user is walking based on the values obtained from the acceleration sensor and the gyro sensor and measuring the number of steps of the user.
The present invention is designed to transition the power state to the Wake-Up state only when an event larger than a given threshold value is received through the tap interrupt algorithm, thereby optimizing the number of transitions to the Wake-Up state and the operation time to minimize power consumption .
In addition, since the power consumption of the system is minimized, the expected battery life of the wearable device can be extended, and the physical battery size is proportional to the battery capacity, so that it is possible to develop a wearable device capable of downsizing the physical size by using the present invention .

Description

[0001] APPARATUS AND METHOD FOR STEP CALCULATION [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for measuring the number of footsteps, and more particularly to a technique for measuring the number of footsteps using a change value of gravity direction acceleration measured by an acceleration sensor.

In general, an activity meter or a digital pedometer reads and processes the output value of an acceleration sensor at a frequency of 30 Hz to 50 Hz to measure the number of steps when a person walks or runs.

In the case of the step counting technique using the polling-based algorithm, the monitoring system reads the acceleration sensor data after the system transitions from the sleep state to the wake-up state every 33 ms every 20 ms, Measure the number.

However, the step counting technique using this conventional polling - based algorithm consumes more power than the step counting technique using the event - based algorithm.

The previous Polling system consumes an average of 635 uA (P_s) power in sleep state and 2.02 mA (P_a) while reading the accelerometer; It consumes 1.32 mA (P_p) during the polling-based step counting algorithm that is set at frequency f. Expressing this as an equation, the system power consumption can be calculated as shown in the following equation.

Using this formula, system level power consumption can be estimated based on the following three states.

- 'Sensor status': the section reading the output of the acceleration sensor

- 'Processing status': Measured number of steps by processing sensor data

- 'Sleep state': the transition to the low power state

The simplest way to save power is to lower the f (polling frequency) in the equation. Applying this method increases the 'sleep state' section and reduces the 'processing state' section. However, the problem with this method is that when the Polling frequency is lowered to 20Hz or less, the accuracy of measuring the number of steps is decreased.

Therefore, we propose a technique to measure the number of steps using tap interrupt algorithm based on gait event as a method to reduce power consumption

The apparatus for measuring the number of steps according to the present invention comprises:

An acceleration sensor for measuring a gravitational acceleration value and a variation amount of the gravitational acceleration value generated when the user is walking;

A gyro sensor used for locating the user; And

A controller for determining whether the user is walking based on a value obtained from the acceleration sensor and the gyro sensor and measuring the number of steps of the user, . ≪ / RTI >

Preferably, the control unit includes:

An initial setting module for setting an average value of gravity direction acceleration values measured by the acceleration sensor, activating a tap interrupt algorithm with the average value as a gravity axis, and transiting the MCU to a sleep state;

Wherein when the tap interrupt is generated, the MCU transits to the wake-up state, and the amount of change of the gravity direction acceleration value by the tap interrupt is measured through the acceleration sensor, A step of determining that the user does not walk when the value is less than a predetermined value;

If the user determines that the user has walked in the stepping module, shifts the MCU to a sleep state after accumulating the number of steps of the user, and if the user does not walk in the stepping module, A step number measuring module for making a transition to a state;

. ≪ / RTI >

Preferably, the average value of the gravity direction acceleration values set by the initial setting module is an average value of the gravity direction acceleration measured by the acceleration sensor for one second.

Preferably, the predetermined value is 0.4 g or more and 0.8 g or less.

A method for measuring the number of steps according to the present invention includes:

a) measuring an average value of gravitational acceleration values measured by an acceleration sensor;

b) the controller activates the tap interrupt algorithm with the measured gravity direction acceleration average value as the gravity axis, and transitions the MCU to the sleep state;

c) when the tap interrupt occurs, the control unit transitions the MCU to the wake-up state, measures the amount of change of the gravity direction acceleration value by the tap interruption through the acceleration sensor, Determining that the user has walked;

d) if the user is determined to have walked, the control unit accumulates the number of steps of the user and transitions the MCU to the sleep state.

Alternatively, after step b)

c-1) when a tap interrupt occurs, the control unit transitions the MCU to a wake-up state, measures a change amount of the gravity direction acceleration value by the tap interruption through the acceleration sensor, Determining that the user has not walked;

d-1) when the controller judges that the user does not walk, the control unit transitions the MCU to the sleep state.

It is designed to transition the power state to the Wake-Up state only when receiving a value larger than a predetermined threshold by applying the tap interrupt algorithm, thereby minimizing power consumption by reducing and optimizing the number of times of transition to the Wake-Up state and the operation time can do.

In addition, since the power consumption of the system is minimized, the expected battery life of the wearable device can be extended, and the physical battery size is proportional to the battery capacity, so that it is possible to develop a wearable device capable of downsizing the physical size by using the present invention .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further understand the technical idea of the invention. And should not be construed as limiting.
1 is a diagram illustrating a detailed configuration of an apparatus for measuring the number of steps according to an embodiment of the present invention.
2 is a flowchart illustrating a method of measuring the number of steps according to an embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

The specific structure or functional description presented in the embodiment of the present invention is merely illustrative for the purpose of illustrating an embodiment according to the concept of the present invention, and embodiments according to the concept of the present invention can be implemented in various forms.

And should not be construed as limited to the embodiments set forth herein, but should be understood to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Furthermore, terms including ordinals such as first, second, etc. used in this specification can be used to describe various elements, but the elements should not be limited by the terms.

The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing in detail several embodiments of the present invention with reference to the accompanying drawings, it is to be understood that the present invention is not limited to the details of construction and the arrangement of components shown in the following detailed description or illustrated in the drawings will be. The invention may be embodied and carried out in other embodiments and carried out in various ways.

Also, terms such as " first "and" second "are used in the present invention and the appended claims for the purpose of explanation and are not intended to represent or imply relative importance or purpose.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

FIG. 1 is a block diagram showing a detailed configuration of an apparatus for measuring the number of footsteps according to an embodiment of the present invention. Referring to FIG. 1, the apparatus for measuring footsteps according to the present invention will now be described.

The apparatus 100 for measuring the number of footsteps according to the present invention includes an acceleration sensor 10 for measuring a gravity direction acceleration value and a variation amount of a gravity direction acceleration value generated when a user is walking;

A gyro sensor 20 used for locating the user; And

And a controller 30 for determining whether the user is walking based on the values obtained from the acceleration sensor and the gyro sensor and measuring the number of steps of the user. The number of steps and the number of steps can be used in the same sense.

The acceleration sensor 10 is a sensor for measuring the acceleration of the moving object, the intensity of the impact, and the amount of change of the values. The acceleration sensor 10 is an acceleration sensor having three axes (X axis, Y axis, Z axis) .

The gyro sensor 20 may be a gyro sensor having three axes (X-axis, Y-axis, Y-axis) as a sensor for measuring a change in azimuth of an object by using a property that maintains a predetermined direction set at the beginning.

The control unit (30) An initial setting module (31) for setting an average value of gravity acceleration values measured by the acceleration sensor, activating a tap interrupt algorithm based on the average value, and transiting the MCU to a sleep state;

When the tap interrupt occurs, the MCU transitions to the wake-up (active) state, and the amount of change in the gravity direction acceleration value caused by the tap interruption is measured through the acceleration sensor. If the tap interruption occurs, A step discriminating module 32 for judging whether or not the discrimination result is " yes "

The step of counting the number of steps of the user and transitioning the MCU to a sleep state (deactivated) when it is judged that the user has walked, and if it is determined that the user has not walked, And a step counting module 33 for counting the number of steps.

The initial setting module 31 obtains an average value by averaging the three-axis gravity direction acceleration values for a predetermined period in order to initially determine the gravity direction. For example, the three-axis gravity direction acceleration value is averaged for one second to obtain an average value.

The average value is determined as a gravity axis, and a gravity tap interrupt algorithm is activated on the axis.

Thereafter, the MCU of the step count measuring apparatus is in a state of transition to the sleep state to minimize power consumption until a tap interrupt occurs.

The tap interrupt algorithm is an algorithm designed to measure a change amount when a gravity axis acceleration value with respect to the gravity axis changes due to a tap interrupt and judge a walk when the change amount is less than a predetermined value, The tap interrupt refers to a change in the gravity direction acceleration value.

The MCU may be a processor or micro controller unit for controlling the step count measuring apparatus according to the present invention.

The constant value may be referred to as a threshold value.

For example, since the amount of change in gravity direction acceleration due to a person's walking activity is about 0.4 g to 0.8 g, the acceleration value of the gravity axis is measured five times in succession. If the value is 0.42 g or more as a threshold value, Can be distinguished. That is, the threshold can be set to 0.4 g or more and 0.8 g or less.

Here, g is a unit representing the magnitude of acceleration applied to an object by gravity.

When a tap interrupt occurs, the step determination module 32 determines whether or not a tap interrupt has occurred by walking the user through the tap interrupt algorithm described above.

If the step determination module 32 determines that the user is walking, the step number measurement module 33 accumulates the number of steps of the user, and then transitions the MCU of the step number measurement device to the sleep state.

The measured number of steps may be displayed on an LCD connected to the step number measuring apparatus according to the present invention.

Hereinafter, a case where the apparatus for measuring the number of steps according to the present invention is implemented as firmware as an embodiment will be described.

The first operation is to initialize the peripherals necessary for system operation. The internal controller such as GPIO, LCD, RTC, UART, and I2C is set as an initial stage, and initialization of the I2C bus can be set to a low-speed interface mode of 100 kHz in consideration of power consumption.

After setting the sampling frequency (200Hz) of the acceleration sensor (ADXL345), the power mode (automatic sleep), the threshold value (0.42g) for tap interrupt and the interrupt output port and using the average value of the output value of the acceleration sensor for one second You can activate the tap interrupt algorithm for this axis by finding the axis that corresponds to the current gravity direction.

Next, the power mode, sampling frequency and angular speed range (8kHz, +/- 200 ° / sec) of the gyro sensor (ITG3200) and interrupt mode can be set and the initialization step can be completed after sensor calibration process.

After this initial phase setup, the firmware main routine will transition to the sleep (LPM0: Low Power Mode 0) state, consuming minimal power and waiting for a tap interrupt.

If a tap interrupt occurs due to a human step, the MCU transitions to a wake-up state and can perform the sensor processing routine first.

Since it takes at least 3ms (PLL-Phase Locked Loop stabilization) time to activate the sleep state gyro sensor in this routine, the gyro sensor is activated first and the acceleration value of the gravity axis is measured five times consecutively. , It is possible to determine the step as a step, increase the measured number of steps, and then read and store the acceleration sensor measurement value and the gyro sensor measurement value.

Then the gyro sensor can be brought to the sleep state and the sensor processing routine can be terminated.

After executing the sensor processing routine, it is possible to display the measured number of steps and the tap interrupt occurrence threshold on the LCD in the firmware main routine.

2 is a flowchart illustrating a method of measuring the number of steps according to an embodiment of the present invention.

The steps of measuring the number of steps according to the present invention include initial setting step s10, transition of the MCI to the sleep state (s20), transition of the MCU to the wake-up state when a tap interrupt occurs, (S30) for determining whether the event has occurred or not.

The initial setting step s10 may include setting an average value of gravity acceleration values measured by the acceleration sensor and setting the average value as a gravity axis.

If it is determined that the tap interruption has occurred due to the user's stepping in the step of determining the step (s30), the step of measuring and storing the number of steps or the number of steps of the pedestrian is performed (step S40) The process proceeds to step s50.

If it is determined that the tap interruption has not occurred due to the user's walking (step s30), the process returns to step s41 to transition the MCU to the sleep state.

As described above, the criterion for determining whether the tap interrupt occurs due to the user's walking in the step of determining the step (s30) is that when the average value of the gravity direction acceleration changes, the change value is equal to or greater than a predetermined threshold value 0.42g , It can be judged that it is not a walk if it is 0.42 g or more, and it is judged that it is not a walk if it is less than 0.42 g.

The present invention has been described in detail with reference to preferred embodiments. It will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above and that various modifications and changes may be made by one of ordinary skill in the art without departing from the scope of the present invention, It is to be understood that the technical idea of the present invention extends to the extent possible.

Claims (6)

An acceleration sensor for measuring a gravitational acceleration value and a variation amount of the gravitational acceleration value generated when the user is walking;
A gyro sensor used for locating the user; And
A controller for determining whether the user is walking based on a value obtained from the acceleration sensor and the gyro sensor and measuring the number of steps of the user, And a step of counting the number of steps.
The apparatus of claim 1,
An initial setting module for setting an average value of gravity direction acceleration values measured by the acceleration sensor, activating a tap interrupt algorithm with the average value as a gravity axis, and transiting the MCU to a sleep state;
Wherein when the tap interrupt is generated, the MCU transits to the wake-up state, and the amount of change of the gravity direction acceleration value by the tap interrupt is measured through the acceleration sensor, A step of determining that the user does not walk when the value is less than a predetermined value;
If the user determines that the user has walked in the stepping module, shifts the MCU to a sleep state after accumulating the number of steps of the user, and if the user does not walk in the stepping module, A step number measuring module for making a transition to a state;
And a step number measuring device
3. The method of claim 2,
Wherein the average value of the gravity direction acceleration values set by the initial setting module is an average value of the gravity direction acceleration measured by the acceleration sensor for one second.
3. The method of claim 2,
Wherein the predetermined value is 0.4 g or more and 0.8 g or less.
a) measuring an average value of gravitational acceleration values measured by an acceleration sensor;
b) the controller activates the tap interrupt algorithm with the measured gravity direction acceleration average value as the gravity axis, and transitions the MCU to the sleep state;
c) when the tap interrupt occurs, the control unit transitions the MCU to the wake-up state, measures the amount of change of the gravity direction acceleration value by the tap interruption through the acceleration sensor, Determining that the user has walked;
d) if the user is determined to have walked, the control unit accumulates the number of steps of the user and transitions the MCU to a sleep state.
6. The method of claim 5,
After step b)
c-1) when a tap interrupt occurs, the control unit transitions the MCU to a wake-up state, measures a change amount of the gravity direction acceleration value by the tap interruption through the acceleration sensor, Determining that the user has not walked;
d-1) when the controller determines that the user does not walk, shifting the MCU to a sleep state.

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