JP7131359B2 - Measuring device, measuring method and program - Google Patents

Description

TECHNICAL FIELD The present invention relates to a measuring device, a measuring method, and a program that help analyze a person's walking style.

Decreased vertical foot-to-floor spacing when stepping forward while walking can be a major factor in increasing the risk of stumbling. In particular, in the process of walking rehabilitation, it is of great significance for the subject to know the vertical distance from the floor to the feet.

In response to this type of request, for example, a method has been proposed to accurately estimate the vertical distance from the floor to the foot using a regression analysis method using an accelerometer worn on the waist, and to evaluate the risk of stumbling. ing. (For example, Patent Document 1)

JP 2017-148287 A

Techniques based on regression analysis that indirectly estimate the vertical distance from the floor to the foot from changes in acceleration during walking, including the technique described in Patent Document 1, are similar to those of patients undergoing rehabilitation. In particular, when there is a large individual difference in walking style due to the degree of disability of an individual, it is difficult to uniformly apply the method, and there is a risk that the accuracy of measurement and evaluation will be significantly reduced.

The present invention has been made in view of the above circumstances, and its object is to accurately measure the vertical distance between an object moving on the ground surface or floor and the object on the ground surface or floor. To provide a measuring device, a measuring method, and a program capable of

According to one aspect of the present invention, distance information corresponding to the distance between the walking surface and the object during movement, measured by three or more distance measuring units attached to an object whose distance from the walking surface changes, is collected. an obtaining means for obtaining the vertical distance between the object and the walking surface based on two pieces of the distance information obtained by the obtaining means and out of the distance information measured by the three or more distance measuring units ; and distance acquisition means for acquiring.

According to the present invention, it is possible to accurately measure the vertical distance between an object moving on the ground surface or the floor and the object on the ground surface or the floor.

1A and 1B are diagrams showing an external configuration and a mounting example of a prototype model of a measuring device according to an embodiment of the present invention; FIG. The figure which shows the basic structure of the sensor part which concerns on the same embodiment. The figure which illustrates arrangement|positioning and the opposing state of the sensor part attached near the tiptoe which concerns on the same embodiment. FIG. 4 is a diagram illustrating the positional relationship between the foot, the sensor unit, and the walking surface, and the distance measurement direction during walking according to the embodiment. FIG. 2 is a block diagram showing the functional configuration of the electronic circuit according to the same embodiment; 4 is a flow chart showing the processing contents during the measurement operation according to the embodiment; The figure explaining the content of the correction|amendment calculation which concerns on the same embodiment. The figure which illustrates the measurement result of the toe clearance along the time series which concerns on the same embodiment.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing the external configuration of an experimental prototype model of the measuring device 10 according to the present embodiment, and an example of how it is worn on a user's foot FT. In the figure, a bridge-shaped toe piece TP is worn over the toe of the user's foot (right foot) FT. On one side of the toe piece TP (in this embodiment, on the outer side near the toe), a substantially semi-cylindrical bottomed sensor unit SU is held so that the inner bottom is parallel to the long axis of the foot FT.

On the other hand, a control box CB is attached to the outer side of the user's foot FT, and the control box CB and the sensor unit SU are wired and connected by a cord CL.

In addition, an indicator lamp IL for visually recognizing the power-on state and the like is arranged in the control box CB.

The control box CB may be attached to the user's waist or the like, and the connection between the control box CB and the sensor unit SU may be performed wirelessly.

Although not shown in the figure, a similar measurement device 10 is also worn on the user's left foot. , each toe clearance measurement shall be performed.

Note that FIG. 1 shows an example as an experimental prototype model of the measuring device 10, but when the measuring device 10 is actually commercialized, the sensor unit SU protrudes greatly to the left and right in the vicinity of the toe of the foot FT. The structure is made as small as possible so as not to hinder the user's walking motion.

FIG. 2 is a diagram showing the basic configuration of the sensor unit SU. Three or more, for example, four, ToF (Time of Flight) sensors TS1 to TS4, which are distance sensors, are arranged at approximately equal intervals on the peripheral inner surface of a bottomed semi-cylindrical sensor frame SF. These ToF sensors TS1 to TS4 are arranged such that the respective distance measurement directions DR1 to DR4 intersect at the cylindrical shaft portion. In other words, the ToF sensors TS1 to TS4 are spaced concentrically around the coaxial portion. The center angle of the ToF sensor TS1 and the ToF sensor TS4 located at both ends with respect to the coaxial portion is selected to be, for example, about 100° to 135°.

FIG. 3 is a diagram exemplifying the arrangement and facing state of the sensor unit SU attached near the toe, which is the tip of the foot FT. The so-called foot, which is the part from the ankle (ankle joint) of a human being, combines flexion and extension of the hip joint, flexion and extension of the knee joint, and dorsiflexion and plantarflexion of the ankle joint during walking. , rotates greatly. The sensor unit SU is mounted so that the shaft portion where the directions of distance measurement intersect is substantially parallel to the main rotation axis of the ankle joint.

In addition, as shown in FIG. 3, the center of the entire distance measurement directions DR1 to DR4 by the four ToF sensors TS1 to TS4 is vertically downward from the position where the sensor unit SU is attached to the walking surface, in the traveling direction. It is arranged so as to face obliquely forward and downward, slightly inclined to a certain forward direction side.

FIG. 4 shows the positional relationship between the foot FT, the sensor unit SU attached to the toe of the measuring device 10, the walking surface, and the distance measurement directions DR1 to DR4 by the four ToF sensors TS1 to TS4 during walking of the user of the measuring device 10. It is a figure which combines and illustrates.

FIG. 4A shows a state in which the sole of the foot is separated from the walking surface and the foot FT is at the rearmost position of the body. Although it depends on individual differences in walking style, in general, the heel portion HL is positioned higher than the toe portion TE, and the entire sole faces backward. At this time, as shown in the figure, the direction of distance measurement by the ToF sensors TS1 and TS2 located on the rear side of the foot FT is relatively close to the perpendicular to the walking plane, and the measured distance is small, resulting in a highly accurate value. becomes. On the other hand, the distance measurement directions of the ToF sensors TS3 and TS4 located on the front side of the foot FT are relatively parallel to the walking plane or do not face the walking plane, resulting in low measurement accuracy. Either the distance becomes a large value, or the measurement itself becomes impossible.

FIG. 4B shows a state in which the entire leg is swung forward and the foot FT is the most forward of the body. Depending on individual differences in walking style, generally, the toe portion TE is positioned higher than the heel portion HL, and the entire sole faces forward. At this time, as shown in the figure, the direction of distance measurement by the ToF sensors TS3 and TS4 located on the front side of the foot FT becomes relatively close to a right angle to the walking plane, and the measured distance is small, resulting in a high measurement accuracy. becomes. On the other hand, the distance measurement directions of the ToF sensors TS1 and TS2 located behind the foot FT are relatively parallel to the walking plane or do not face the walking plane, resulting in low measurement accuracy. The measured distance becomes a large value, or the measurement itself becomes impossible.

FIG. 5 is a block diagram showing the functional configuration of an electronic circuit included in the measuring device 10. As shown in FIG.
A processor 11 , a ToF sensor unit (SU) 12 , a key input/indicator unit 14 , a memory interface (I/F) 15 and a wireless communication unit 16 are connected to the bus B.

The processor 11 includes a CPU internally equipped with an RTC (Real Time Clock) that keeps current time information regardless of whether the power is turned on, a RAM that serves as a work memory for the CPU, an operation program executed by the CPU, fixed data, and the like. and a ROM that stores in a nonvolatile manner. The processor 11 controls the operation of the measuring device 10 as a whole.

A ToF sensor unit (SU) 12 measures distance values in four directions by the ToF sensors TS1 to TS4 under the control of the processor 11. FIG.

The key input/indicator unit 14 has a power key for turning on/off the power, and an indicator lamp IL for indicating the operating state by turning on/off. For example, by long-pressing the power key from the power-on state, the memory card 17 for recording the measurement results in the measurement apparatus 10 or an external device wirelessly connected by the wireless communication unit 16 is selected as the output destination of the measurement results. One of the devices may be selectable.

The indicator lamp IL lights up when the power is turned on according to the selection of the output destination of the measurement results. When an external device wirelessly connected by the communication unit 16 is selected, the flashing display makes it possible to easily see the selected output destination of the measurement result at that time.

The memory interface 15 records the measurement results sent from the processor 11 via the bus B to the memory card 17 at any time while the memory card 17 is attached to the card slot CS of the control box CB.

The wireless communication unit 16 complies with, for example, the Bluetooth (registered trademark) LE (Low Energy) standard, which is one of short-range wireless communication standards, and is wirelessly connected via an antenna 18 to an external device that has been paired in advance. , to output the measurement results.

In addition, when the user wears a total of two measuring devices 10 on the left and right feet FT and performs measurement, the wireless communication unit 16 of one measuring device 10 only transmits and outputs the measurement result, and the other The wireless communication unit 16 of the measuring device 10 receives the measurement result transmitted from the wireless communication unit 16 of one of the measuring devices 10, summarizes it together with the measurement result of its own device, and transmits it to the external device. It is also possible to perform pairing setting in advance.

In the block diagram of FIG. 5 described above, electronic circuits other than the ToF sensor unit (SU) 12 are arranged in the above-described control box CB.

Next, the operation of this embodiment will be described.
FIG. 6 is a flow chart showing the basic processing contents of the measurement operation executed by one measuring device 10 after the power is turned on. The processing in FIG. 6 is mainly executed by the processor 11 based on the operation program.

At the beginning of power-on, the processor 11 causes the ToF sensor unit 12 to perform a distance measurement operation in order to absorb errors in the mounting position of the measuring device 10 on the foot FT, and the distance information obtained by the correction calculation described later is used as a reference. A zero correction process is executed to set the value to zero (step S101).

At this time, the user needs to operate the power key of the key input/indicator section 14 in a state in which the foot FT is completely on the walking surface and the toe clearance is zero.

After that, the processor 11 performs distance measurement with the ToF sensor unit 12 at a preset constant time period, for example, 0.04 [seconds] (step S102).

The processor 11 selects the distance information with the closest distance and the distance information with the next closest distance from the four pieces of distance information acquired by the ToF sensor unit 12, and then, from the two distance information, By applying correction calculation, the distance value to the walking surface in the vertical direction is calculated as the toe clearance.

FIG. 7 is a diagram for explaining the contents of the correction calculation. Consider the axial position, which is the intersection of the distance measurement directions DR1 to DR4 of the ToF sensors TS1 to TS4 constituting the ToF sensor unit 12, to the walking plane.

Among the closest distance and the next closest distance, a is the distance on the heel side of the foot FT, b is the distance on the toe side, d is the toe clearance that is the vertical distance, and the angle formed by each direction of the distances a and b If α (known from the arrangement relationship of two ToF sensors that employ distance information) and the angle formed by each direction of the vertical distance d and distance b is θ, the distance d is obtained by the following equation
d=a・b・sinα/√(a ² −2・a・b・cos α+b ² ) (1)
is obtained by

The distance d obtained here is the distance from the axial position, which is the intersection point of the distance measuring directions DR1 to DR4 of the ToF sensors TS1 to TS4, to the walking plane, as described above, and therefore includes the inclination θ between the axial position and the toe. A further correction calculation is performed according to the positional relationship to calculate the toe clearance, which is the distance from the correct toe position to the walking surface (step S103).

At this time, the slope θ is
θ = cos ^-1 (d/b) (2)
is obtained by

After calculating the distance of the toe clearance, processor 11 determines whether or not recording to memory card 17 is selected as an output destination at that time (step S104).

If it is determined that recording to the memory card 17 is selected (YES in step S104), the processor 11 stores the calculated toe clearance information and the measurement time information in the memory card 17 via the memory interface 15. are recorded in association with each other (step S105).

If it is determined in step S104 that recording to the memory card 17 is not selected and set (NO in step S104), the selected output destination at that time is the connection via the wireless communication unit 16. Therefore, the processor 11 transmits the calculated toe clearance information to the external device via the wireless communication unit 16 and the antenna 18 in association with the measurement time information (step S106).

After outputting the toe clearance, processor 11 returns to the process from step S102 to perform the next measurement.

FIG. 8 exemplifies toe clearance measurement results in time series obtained by the ToF sensor unit 12 . As shown in the figure, the period in which the toe clearance is almost stable at a low position is the stance phase when the foot FT is in contact with the walking surface and the toe clearance becomes zero (the foot FT does not move). .

The subsequent period in which the toe clearance increases and decreases is the swing period in which the foot FT is floating in the air. The point at which the toe clearance is the smallest during the swing phase indicates the timing of the minimum toe clearance.
The timing at which minimum toe clearance occurs is the timing at which the swing leg is about to overtake the stance leg. At this timing, if the toe touches the walking surface and the movement of the free leg is hindered, the weight that has moved forward will be lost, increasing the risk of falling. Knowing the toe clearance is an index of how safely a person can walk in response to the unevenness of the walking surface.

In this embodiment, a ToF sensor is used as a distance sensor. , Some models are not good at high-speed sampling.

In such a case, for example, an inertial sensor unit having an acceleration sensor and a gyro sensor may be further provided, and the trajectory of the output of the ToF sensor may be estimated and interpolated by dead reckoning (autonomous navigation) technology.

When using the inertial sensor unit, there is a problem that integration errors are generally accumulated over time. However, in this embodiment, as shown in FIG. The integral error can be reset every stance phase when it becomes zero, and the accumulation of the integral error can be prevented.

In addition, in this embodiment, the sensor section is provided on the outer side near the toe. However, when the ankle joint inverts and rolls out severely and the toe tilts greatly, the sensor section is provided on both sides in the vicinity of the toe. By doing so, it is possible to estimate the inclination from both measured values and perform correction calculation.

As described in detail above, according to this embodiment, the vertical distance between an object such as a human foot and the walking surface can be accurately adjusted even when there is a large individual difference in walking style. measurement becomes possible.

Further, in this embodiment, the ToF sensors are spaced apart substantially on the circumference of the horizontal axis perpendicular to the axial direction close to the moving direction of the object. Directional spacing can be measured more accurately.

In addition, since the ToF sensor is attached near the tip of the object in the moving direction, it is possible to acquire the relationship with the walking surface accompanying movement in an easy-to-understand form.

In addition, in the present embodiment, of the plurality, three or more distance sensors arranged adjacently, two distance sensors having a short measurement distance are used to calculate the toe clearance in the vertical direction. Clearance can be measured with high accuracy.

When calculating the clearance, an accurate clearance is corrected and calculated by a simple arithmetic expression using the values measured by the two distance sensors and angle information known from the positional relationship of the two distance sensors. Therefore, there is no increase in the processing load of the control system.

In addition, in this embodiment, the measured results can be recorded or output so as to be transmitted to an external device, so that the clearance obtained as a result of time-series measurement can be used for objective analysis processing. etc., can be used more effectively.

In particular, by using the human foot as the moving object, it is possible to directly measure the way the person walks, which was difficult to measure with high accuracy due to the large individual differences in walking, making it possible to make accurate and easy decisions. can be lowered.

In this regard, by measuring the toe clearance in particular, it is possible to make an accurate judgment for users who are particularly prone to stumbling, which can contribute to elderly people and users undergoing rehabilitation due to some kind of disability. .

Although the present embodiment has been described as a case where it is applied to a dedicated measuring device worn by a user on the foot FT, the present invention is not limited to this. Also, the vertical direction between various moving objects and the walking surface (landing surface), such as when automatically executing preliminary movements at the time of landing with a drone as a toy, without limiting the moving object to a human foot. can also be applied to the control operation according to the interval of

Further, in the measuring device 10 according to the present embodiment, the measuring device 10 is provided with the sensor unit SU, but the measuring device 10 does not include the sensor unit SU, and the distance information measured by the sensor unit SU is acquired. , toe clearance may be measured based on the obtained distance information.

Also, in this embodiment, the toe clearance is measured, but the vertical distance from the floor to the heel or from the floor to the arch of the foot may be measured.

Also, in the present embodiment, the ToF sensor is used as the distance sensor, but other than the ToF sensor, for example, a distance sensor using ultrasonic waves or the like may be used.

In addition, the present invention is not limited to the above-described embodiments, and can be variously modified in the implementation stage without departing from the scope of the invention. Moreover, each embodiment may be implemented in combination as much as possible, and in that case, the combined effect can be obtained. Furthermore, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, the problems described in the column of problems to be solved by the invention can be solved, and the effects described in the column of effects of the invention is obtained, the configuration from which this constituent element is deleted can be extracted as an invention.

The invention described in the original claims of the present application is appended below.
[Claim 1]
Acquisition means for acquiring distance information measured by a plurality of or three or more distance measuring units attached to an object whose distance from a walking surface changes during movement;
a selection means for selecting two distance measurement information from the distance information obtained by the plurality, three or more distance measurement units, which are acquired by the acquisition means;
distance acquisition means for acquiring a vertical distance between the object and the walking plane based on the two pieces of distance measurement information selected by the selection means;
A measuring device comprising a
[Claim 2]
2. The measuring device according to claim 1, wherein said plurality of distance measuring units are spaced apart substantially on the circumference of a lateral axis orthogonal to an axial direction close to the moving direction of said object.
[Claim 3]
3. The measuring device according to claim 2, wherein the plurality of distance measuring units are attached near the tip of the object on the moving direction side whose distance from the walking surface changes during movement.
[Claim 4]
each of the plurality of distance measuring units measures distance information from the distance measuring unit to the walking plane via the lateral axis position;
The selection means selects the shortest distance information and the next shortest distance information among the distance information measured by each of the plurality of distance measuring units,
4. The measuring device according to claim 2 or 3.
[Claim 5]
Based on the two distance measurement information selected by the selection means and the angles formed by the two distance measurement units corresponding to the two distance measurement information with respect to the horizontal axis position, 5. A measuring device according to any one of claims 2 to 4, for obtaining the vertical distance between the object and the walking plane.
[Claim 6]
6. The measuring device according to any one of claims 1 to 5, further comprising an output section for outputting information on the vertical distance to said walking plane acquired by said distance acquiring means.
[Claim 7]
6. The object according to any one of claims 2 to 5, wherein the object is a human foot, the movement is human walking, and the lateral axis is parallel to the walking axis of the human ankle. measuring device.
[Claim 8]
The object is a human foot, the tip of the object is the toe of the human foot, the movement is human walking, and the lateral axis is a single rotation axis of the human ankle during walking. 4. The measuring device according to claim 3, which is parallel.
[Claim 9]
9. The measuring device according to claim 8, wherein said distance acquiring means acquires a toe clearance which is a vertical distance between the toe of said person's foot and said walking surface when said person walks.
[Claim 10]
10. The measuring device according to any one of claims 1 to 9, further comprising the plurality of distance measuring units.
[Claim 11]
A measuring method with a measuring device,
an acquisition step of acquiring distance information measured by a plurality, three or more distance measuring units attached to an object whose distance from a walking surface changes during movement;
a selection step of selecting the top two distance measurement information among the distance information measured by the plurality, three or more distance measurement units, which are acquired in the acquisition step;
a distance acquisition step of acquiring a vertical distance between the object and the walking plane based on the two pieces of ranging information selected in the selection step;
measurement method.
[Claim 12]
A program executed by a computer incorporated in a measuring device, the computer comprising:
Acquisition means for acquiring distance information measured by a plurality of or three or more distance measuring units attached to an object whose distance from a walking surface changes during movement;
selection means for selecting two distance measurement information from the distance information measured by the plurality, three or more distance measurement units acquired by the acquisition means;
distance acquisition means for acquiring a vertical distance between the object and the walking plane based on the two pieces of distance measurement information selected by the selection means;
A program that works as

10... Measuring device 11... Processor 12... ToF sensor unit 14... Key input/indicator unit 15... Memory interface (I/F)
16... Wireless communication unit 17... Memory card 18... Antenna B... Bus CB... Control box CL... Code CS... Card slot FT... (user's) foot IL... Indicator lamp SF... Sensor frame SU... Sensor part TP... Toe piece

Claims (12)

Acquisition means for acquiring distance information corresponding to the distance between the moving surface and the object measured by three or more distance measuring units attached to an object whose distance from the surface changes;
distance acquisition means for acquiring a vertical distance between the object and the walking surface based on two of the distance information obtained by the acquisition means and among the distance information measured by the three or more distance measurement units ; ,
A measuring device comprising: The three or more distance measuring units are respectively spaced apart on a substantially circular circumference of a horizontal axis orthogonal to an axial direction close to the moving direction of the object. 1. The measuring device according to 1. 3. The measuring apparatus according to claim 2 , wherein the three or more distance measuring units are attached near the tip of the object on the moving direction side. each of the three or more distance measuring units acquires distance information corresponding to the distance between the walking surface and the object from the distance measuring unit via the lateral axial position;
The distance acquisition means further comprises selection means for selecting the shortest distance information and the next shortest distance information among the distance information measured by each of the three or more distance measuring units. 4. The measuring device according to claim 2 or 3. Based on the two distance measurement information selected by the selection means and the angle formed by the two distance measurement units corresponding to the two distance measurement information with respect to the horizontal axis position, 5. A measuring device according to claim 4 , characterized in that it acquires the vertical distance of said object to said walking plane. 6. The measuring apparatus according to any one of claims 1 to 5, further comprising an output unit that outputs information on the vertical distance between the object and the walking plane obtained by the distance obtaining means. 6. The method of claims 2 to 5 , wherein said object is a human foot, said movement is human walking, and said lateral axis is parallel to a walking axis of a human ankle. A measuring device according to any one of the preceding claims. The object is a human foot, the tip of the object is the toe of the human foot, the movement is human walking, and the lateral axis is a single rotation axis of the human ankle during walking. 4. Measuring device according to claim 3, characterized in that they are parallel. 9. The measuring device according to claim 8, wherein said distance acquisition means acquires a toe clearance which is a vertical distance between the toe of said person's foot and said walking surface when said person walks. 10. The measuring device according to any one of claims 1 to 9, comprising a plurality of said distance measuring units. A measuring method with a measuring device,
an acquisition step of acquiring distance information corresponding to the distance between the walking plane and the object during movement, measured by three or more distance measuring units attached to an object whose distance from the walking plane changes;
A distance acquisition step of acquiring a perpendicular distance between the object and the walking plane based on two of the distance information obtained in the acquisition step, out of the distance information measured by the three or more distance measurement units . When,
A measuring method comprising : A program executed by a computer incorporated in a measuring device, the computer comprising:
Acquisition means for acquiring distance information corresponding to the distance between the moving surface and the object measured by three or more distance measuring units attached to an object whose distance from the surface changes ;
distance acquisition means for acquiring a vertical distance between the object and the walking plane based on two of the distance information obtained by the acquisition means and among the distance information measured by the three or more distance measurement units ;
A program to function as

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