JPWO2012169051A1 - Drop determination device and drop determination method - Google Patents

Abstract

The drop determination device (10) includes a sensor unit (11), an impact calculation unit (13), and an application processing unit (14). The sensor unit (11) detects acceleration within the predetermined range. The impact calculation unit (13) calculates an acceleration outside the predetermined range using the acceleration detected by the sensor unit (11). The application processing unit (14) determines the presence or absence of a drop using the acceleration calculated by the impact calculation unit (13). Thereby, a fall determination apparatus (10) determines fall using a low-range acceleration sensor.

Description

  The present invention relates to a fall determination device and a fall determination method.

  Conventionally, there is a technique for detecting the acceleration of an object that is moving using an acceleration sensor and determining the state of the object based on the detection result. Acceleration sensors that realize such technology include a low-range sensor suitable for detecting low acceleration and a high-range sensor suitable for detecting high acceleration. The low-range acceleration sensor has a high resolution in detecting an acceleration of about ± 5 G or less, and thus is suitable for state determination such as walking with an acceleration of 0.5 to 2.0 G. For example, for a portable terminal Used for pedometer applications. On the other hand, the high-range acceleration sensor has a high resolution in detecting an acceleration of about ± 70 G, and thus is suitable for determining a state such as a drop with an impact of several tens to 100 G. In recent years, there has also been proposed a portable terminal that has a plurality of acceleration sensors with different ranges and switches these sensors depending on the mode.

JP 2008-174771 A

  However, the range of acceleration that can be accurately detected by the acceleration sensor is limited for each sensor, and there is no acceleration sensor having high resolution in any range. For example, when a portable terminal is dropped, it is accompanied by a severe impact, so an accurate acceleration cannot be detected by a low range acceleration sensor. In view of such a situation, it can be considered that the fall determination is performed by a high range acceleration sensor, but it is difficult to apply the high range acceleration sensor to an application that requires high resolution acceleration detection in a low range. . That is, when a high-range acceleration sensor is mounted on a portable terminal, there is a problem that it is difficult to realize application functions such as a pedometer. In addition, as described above, it is possible to detect acceleration in a wide range by having both a low range and a high range acceleration sensor, but mounting multiple acceleration sensors on a portable terminal reduces the size and weight. It becomes a factor to inhibit.

  The disclosed technology has been made in view of the above, and an object thereof is to provide a fall determination device and a fall determination method capable of determining a fall using a low-range acceleration sensor.

  In order to solve the above-described problems and achieve the object, a fall determination device disclosed in the present application includes a detection unit, a calculation unit, and a determination unit in one aspect. The detection unit detects an acceleration within the predetermined range. The calculation unit calculates an acceleration outside the predetermined range using the acceleration detected by the detection unit. The determination unit determines whether or not there is a fall using the acceleration calculated by the calculation unit.

  According to one aspect of the fall determination device disclosed in the present application, it is possible to determine a fall using a low-range acceleration sensor.

FIG. 1 is a diagram illustrating a functional configuration of a portable terminal. FIG. 2 is a diagram illustrating a data storage example in the acceleration conversion table in the first embodiment. FIG. 3 is a diagram illustrating a hardware configuration of the portable terminal. FIG. 4 is a flowchart for explaining the operation of the portable terminal according to the first embodiment. FIG. 5 is a diagram for explaining a method of calculating the impact time and the acceleration at the time of impact in the first embodiment. FIG. 6 is a diagram illustrating a data storage example in the acceleration conversion table in the second embodiment. FIG. 7 is a flowchart for explaining the operation of the portable terminal according to the second embodiment. FIG. 8 is a diagram for explaining a method for calculating the impact time and the acceleration range at the impact in the second embodiment. FIG. 9 is a diagram illustrating a computer that executes a fall determination program.

  Hereinafter, embodiments of the drop determination device and the drop determination method disclosed in the present application will be described in detail with reference to the drawings. In addition, the fall determination apparatus and the fall determination method which this application discloses are not limited by this Example.

  First, the configuration of a portable terminal according to an embodiment of the drop determination device disclosed in the present application will be described. FIG. 1 is a diagram illustrating a functional configuration of a portable terminal 10 according to the present embodiment. As illustrated in FIG. 1, the portable terminal 10 includes a sensor unit 11, a sampling processing unit 12, an impact calculation unit 13, and an application processing unit 14. Each of these components is connected so that signals and data can be input and output in one direction or in both directions.

  The sensor unit 11 is a low-range acceleration sensor whose range value is set to ± 4G. Therefore, the sensor unit 11 can detect (actually measure) acceleration up to + 4G as the upper limit value and can detect (actually measure) acceleration up to −4G as the lower limit value. The sensor unit 11 is a well-known and commonly used sensor, and will not be described in detail. However, the sensor unit 11 is a triaxial acceleration sensor that detects acceleration in three axial directions orthogonal to each other. The acceleration in the X-axis direction is a displacement value that accompanies movement in the left-right direction in a motion (walking or dropping) with acceleration. That is, the acceleration in the X-axis direction is a lateral movement amount based on the mounting posture of the sensor unit 11 at a predetermined time point, a leftward movement amount is positive, and a rightward movement amount is negative. The acceleration in the Y-axis direction is a displacement value that accompanies the movement in the vertical direction in a motion with acceleration. That is, the acceleration in the Y-axis direction is a vertical movement amount based on the mounting posture of the sensor unit 11 at a predetermined point in time, and an upward movement amount is positive and a downward movement amount is negative. The acceleration in the Z-axis direction becomes a displacement value associated with movement in the front-rear direction in a motion with acceleration. That is, the acceleration in the Z-axis direction is a movement amount in the front-rear direction with reference to the mounting posture of the sensor unit 11 at a predetermined time, and the movement amount in the front direction is positive and the movement amount in the rear direction is negative.

  The sampling processing unit 12 periodically samples the acceleration value detected by the sensor unit 11 and outputs the value to the impact calculation unit 13. The sampling cycle is preferably a short cycle of, for example, about 1 ms, and more preferably about 0.1 ms, from the viewpoint of performing acceleration detection in a high range and, hence, impact calculation with high accuracy.

  The impact calculation unit 13 calculates an out-of-range acceleration exceeding 4 G using the acceleration input from the sampling processing unit 12 after being detected by the sensor unit 11. That is, the impact calculation unit 13 determines the time when the acceleration detected by the sensor unit 11 exceeds 4G, the time when the acceleration returns within the range of 4G or less, the slope of the acceleration before the excess time, and after the return time The acceleration out of range is calculated using the acceleration gradient at. Then, the impact calculation unit 13 outputs the calculated acceleration value to the application processing unit 14 as an estimated value of acceleration at the time of impact.

  The application processing unit 14 converts the acceleration value (estimated value) at the time of impact calculated by the impact calculation unit 13 into an actual measurement value during the activation of the fall determination application, compares the value with a threshold value, If the subsequent acceleration is equal to or greater than the threshold value, it is determined that there has been a drop. And the application process part 14 displays this fall determination result.

  The application processing unit 14 has an acceleration conversion table 141a. FIG. 2 is a diagram illustrating a data storage example in the acceleration conversion table 141a for converting the acceleration (estimated value) at the time of impact into an actual measurement value in the first embodiment. As shown in FIG. 2, the acceleration conversion table 141 a stores the acceleration at impact calculated by the impact calculation unit 13 as “M estimated value”, and the acceleration at impact measured in advance by the high range acceleration sensor is “measured”. “Value”. For example, when the M estimated value is calculated to be “5.00 G”, the actual acceleration value is set in advance to “5.50 G”, so “5.50 G” is compared with the threshold value. Used as. Similarly, when the M estimated value is calculated as “80.20G”, the actual acceleration value set in advance is “80.68G”, and this value is used for determining whether or not the vehicle is dropped. Is done. As described above, the acceleration at impact as the M estimated value calculated by the impact calculation unit 13 is corrected to an actual measurement value by the application processing unit 14.

  The correspondence relationship between the M estimated value and the actual measurement value set in the acceleration conversion table 141a can be updated based on the actual acceleration measured at the time of impact (dropping, throwing, etc.) of the portable terminal 10. That is, the application processing unit 14 appropriately updates the correspondence relationship in the acceleration conversion table 141a according to the impact characteristics of the sensor unit 11 or the calculation accuracy of the M estimated value, and always maintains the latest state. Thereby, the application process part 14 can perform fall determination based on the exact acceleration value close | similar to the actual condition with reference to the acceleration conversion table 141a. Therefore, the portable terminal 10 can obtain a more accurate drop determination result. As a result, the reliability of the portable terminal 10 is improved.

  Note that the portable terminal 10 described above is physically realized by, for example, a mobile phone. FIG. 3 is a diagram illustrating a hardware configuration of a mobile phone as the mobile terminal 10. As shown in FIG. 3, the portable terminal 10 physically includes a CPU (Central Processing Unit) 10a, an acceleration sensor 10b, a memory 10c, a display device 10d, and a wireless device 10e having an antenna A. Have. As described above, the sensor unit 11 is realized by the acceleration sensor 10b. The sampling processing unit 12, the impact calculation unit 13, and the application processing unit 14 are realized by an integrated circuit such as the CPU 10a, for example. The range value, drop determination threshold, acceleration sampling value, and acceleration conversion table 141a are held in a memory 10c such as a RAM (Random Access Memory), a ROM (Read Only Memory), and a flash memory. The impact calculation result is displayed on a display device 10d such as an LCD (Liquid Crystal Display).

  Next, the operation of the portable terminal 10 will be described. In the following description of the operation, it is assumed that the user drops the portable terminal 10 having an acceleration range of ± 4G onto the floor surface for some reason.

  FIG. 4 is a flowchart for explaining the operation of the portable terminal 10. When the user activates the drop determination application of the portable terminal 10 (S1), the sampling processing unit 12 acquires acceleration values for each of the three axis directions input from the sensor unit 11 at a predetermined period, thereby obtaining the acceleration value. Sampling is started (S2).

The impact calculation unit 13 always holds acceleration values sampled one and two hours before the latest sampling time as sampling values (S3). The impact calculator 13 monitors whether or not the latest sampled value exceeds ± 4G, which is the range of the sensor unit 11, while holding the sampled value (S4). As a result of the monitoring, when the sampling value exceeds the range of the sensor unit 11 (S4; Yes), the process proceeds to S5. Note that the sampling values a ₁ and a _{2 for} two hours before the range are exceeded are not erased even if the next sampling value is obtained, and are continuously held in the memory 10c.

In S5, the impact calculation unit 13 holds the sampling value b ₂ immediately after returning to the range again after exceeding the range, and the sampling value b ₃ one hour after that. Furthermore, the impact calculating unit 13, the time _{t 1} to shake off the range, and a time _{t 2} which has returned to the range to retain in the memory 10c (S6). The time t ₁ can be calculated as the time when the acceleration sampling by the sensor unit 11 stops. Further, the time t ₂ can be calculated as the time when the acceleration sampling by the sensor unit 11 is resumed. However, the time t ₂ can also be calculated by adding the number of samples in the sampling period × time t ₁ t ₂ to the time t _1. It is.

  As a result of the monitoring, while the sampling value is within the range of the sensor unit 11 (S4; No), the portable terminal 10 holds the sampling values for the two most recent times by the impact calculation unit 13. Continue (S3). Since the sampling value held at this time remains as data for two hours, the free capacity of the memory 10c is not wasted even if the sampling process is executed for a long time by starting the drop determination application.

In S7, the impact calculating unit 13 calculates the slope S ₁ of the acceleration in the prior shaken off range. Since the impact calculation unit 13 holds the sampling values a ₁ and a ₂ immediately before exceeding the range in S3, the slope S ₁ is determined by | a ₁ −a ₂ | / c from these values and the sampling period. Is calculated by Similarly, in S8, the impact calculating unit 13 calculates the acceleration of the slope S ₂ in After returning within range. Since the impact calculation unit 13 holds the sampling values b ₂ and b ₃ immediately after the return of the range in S5, the slope S ₂ is determined from these values and the sampling period, | b ₂ −b ₃ | / c. Is calculated by Each calculation result is held in the memory 10c.

Next, the impact calculation unit 13 receives the time t _c when the portable terminal 10 receives an impact from the times t ₁ and t ₂ held in S6 and the slopes S ₁ and S ₂ held in S7 and S8. , And the acceleration M at that time is calculated (S9).

Hereinafter, the calculation method of the impact time t _c and the impact acceleration M will be described more specifically with reference to FIG. In FIG. 5, a time t [ms] is defined on the x axis and an acceleration [G] is defined on the y axis. The time t _0, the mobile terminal 10 is a time in contact with the floor to fall. Time t ₁ is the time when the acceleration detected by the sensor unit 11 exceeds + 4G, which is the upper limit value of the range, and time t ₂ is the time when the detected acceleration returns to the range again. . Further, the sampling period is set to 1 [ms], the slope held in S7 (the slope between circles a _{1 and} a _{2 in} FIG. 5) is set to S _1, and the slope held in S8 (the triangle mark b _{2 in} FIG. 5). between b ₃ gradient) be _{S 2.} Since circle a ₃ is acceleration detected by the sensor unit 11 is a sampled value immediately after exceeding the range upper limit (out of range), according acceleration has not been detected in practice, acceleration detected In order to distinguish them from the circles a ₁ and a ₂ representing the sampling values, the broken lines are represented by broken lines. Similarly, a triangle mark b ₁ is a sampling value immediately before the acceleration detected by the sensor unit 11 returns to within the range (outside the range), but since this acceleration is not actually detected, the detected acceleration In order to distinguish from the triangle marks b ₂ and b ₃ representing the sampling values, they are represented by broken lines.

Under the above conditions, if the impact time to be calculated in S9 is t _c , t _c −t ₁ : t ₂ −t _c = S ₂ : S ₁ , and therefore, t _c It can be calculated by (1).

Impact time t _c = (S ₁ t ₁ + S ₂ t ₂ ) / (S ₁ + S ₂ ) (1)

Further, under the above conditions, if the acceleration at impact to be calculated in S9 is M, M = S ₁ t _c + b and 4 = S ₁ t ₁ + b (b is a constant), The acceleration M at t _c can be calculated by the following mathematical formula (2).

Acceleration upon impact M = S ₁ S ₂ (t ₂ −t ₁ ) / (S ₁ + S ₂ ) +4 (2)

That is, the impact calculation unit 13 obtains the two-dimensional coordinates of the intersection D between the straight line B passing through the circles a ₁ and a ₂ and the straight line C passing through the triangles b ₂ and b _3, and calculates the x-coordinate value thereof. The impact time t _c is estimated, and the y coordinate value is estimated as the impact acceleration M.

  In S10, the application processing unit 14 converts the acceleration M calculated by the impact calculation unit 13 in S9 into an actual measurement value. This conversion process is executed with reference to the acceleration conversion table 141a described above. The acceleration M is not a value actually detected by the sensor unit 11 but a value (estimated value) calculated based on an actual measurement value to the last, and therefore may not necessarily match an actual acceleration value. There is. Therefore, the application processing unit 14 estimates based on the correspondence between the estimated value and the actually measured value set in the acceleration conversion table 141a so that the acceleration value used for the fall determination approximates the actual acceleration value. Correction is performed to convert the value into an actual measurement value. For example, when the impact acceleration calculated by the impact calculator 13 in S9 is “80.00”, it is converted to “80.46” (see FIG. 2).

  In S11, the application processing unit 14 determines whether or not the portable terminal 10 has fallen from the acceleration at impact (measured value in FIG. 2) after conversion in S10 and the threshold value T1 illustrated in FIG. In other words, the application processing unit 14 compares the magnitude relationship between the acceleration at impact M and a preset threshold value T1, and determines that there is a drop if the acceleration at impact M ≧ the threshold value T1. On the other hand, if the relationship of acceleration upon impact M <threshold value T1 is satisfied, the application processing unit 14 determines that there is no drop. At the time of dropping, acceleration of several tens to 100 G is generated in the portable terminal 10 depending on the material of the contact surface. Therefore, for example, 20 G is set as the threshold T1. However, this set value can be appropriately changed according to the specification of the portable terminal 10 or the calculation accuracy of the estimated value.

If it is determined that there is drop in S11, the impact time t _c which is calculated in S9 as the "drop time", together with information indicating that there is dropped, it is recorded in the memory 10c. At the same time, the display device 10d displays a message indicating that a fall has occurred, for example, “There was a fall around 10:20:35 on May 19”.

As described above, the portable terminal 10 according to the present embodiment includes the sensor unit 11, the impact calculation unit 13, and the application processing unit 14. The sensor unit 11 detects acceleration within the predetermined range. The impact calculation unit 13 calculates acceleration outside the predetermined range using the acceleration detected by the sensor unit 11. The application processing unit 14 determines whether or not there is a fall using the acceleration calculated by the impact calculation unit 13. More specifically, the impact calculation unit 13 calculates the acceleration outside the predetermined range using the time t ₁ , the time t ₂ , the acceleration gradient S _1, and the acceleration gradient S ₂ . Time t ₁ is the time when the acceleration detected by the sensor unit 11 exceeds the predetermined range. Time t ₂ is the time at which the acceleration has returned to within the predetermined range. Slope _{S 1} is the slope of the acceleration at time _{t 1} before. Slope _{S 2} is the slope of the acceleration after the time _{t 2.} The application processing unit 14 determines whether or not there is a fall based on whether or not the acceleration calculated by the impact calculation unit 13 is greater than or equal to a predetermined value.

  According to the portable terminal 10 according to the present embodiment, a high-range acceleration sensor is mounted by calculating the time of impact and the acceleration at that time from the acceleration detected using the low-range acceleration sensor. Without it, it is possible to determine the presence or absence of a drop with a high range impact. In other words, the portable terminal 10 calculates the acceleration in a range that cannot be measured by the low range acceleration sensor due to insufficient range by using a predetermined mathematical expression, and estimates the acceleration value outside the range based on the result. As a result, the portable terminal 10 can quickly determine when and how much impact has occurred. Therefore, if the portable terminal 10 records and displays the determination result as history information, the user can easily recognize that there was a fall and the time. Further, not only the user but also a third party such as a telecommunications carrier (carrier) or manufacturer can refer to the history information to easily and quickly know that there has been a fall. For this reason, even if the portable terminal 10 is damaged or becomes unusable due to an impact caused by dropping, the third party notifies the user that the cause is falling based on the dropping time. It becomes possible.

In particular, according to the portable terminal 10 according to the present embodiment, the inclination immediately before the acceleration exceeds the range among the inclinations of the acceleration before the time t _{1 is used} as the inclination S ₁ . Acceleration of the slope at time t ₁ before, after contact with the floor of the portable terminal 10, reaches until the acceleration exceeds the range, range upper limit with increasing accuracy (4G), the shake off the range become. Therefore, the portable terminal 10 uses the value immediately before the measured value of the acceleration swings out of the range (measured value as close as possible to the outside of the range as much as possible) to calculate the estimated acceleration. Can be calculated. As a result, the portable terminal 10 can perform more accurate acceleration estimation. On the other hand, regarding the inclination on the side returning to the range, the portable terminal 10 uses the inclination immediately after the acceleration returns to the range among the inclinations of the acceleration after time t ₂ as the inclination S ₂ . Acceleration slope after the time t ₂ after contact with the floor of the portable terminal 10, as the time passes, approaches the reduce the acceleration value while reducing the accuracy 0 [G]. Therefore, the portable terminal 10 uses the value immediately after the measured value of acceleration returns to the range (measured value as close as possible to the outside of the range as much as possible) to calculate the estimated acceleration, so that there are few errors even outside the range. Acceleration can be calculated. As a result, the portable terminal 10 can perform more accurate acceleration estimation.

  Next, the portable terminal in Example 2 will be described. The second embodiment is different from the first embodiment in the method of calculating the impact time and the acceleration at the time of the impact. That is, in the first embodiment, the portable terminal 10 directly calculates the impact time and the acceleration value at the time of impact from the intersection of two straight lines, but in the second embodiment, the impact time is calculated first, The range of acceleration values at that time is obtained.

  The configuration of the portable terminal in the second embodiment is the same as that of the portable terminal 10 in the first embodiment except for data stored in the acceleration conversion table. Therefore, the same reference numerals are used for common components, and illustration and detailed description of the entire configuration are omitted. Hereinafter, an acceleration conversion table having an aspect different from that of the first embodiment will be described.

  The application processing unit 14 according to the second embodiment includes an acceleration conversion table 141b. FIG. 6 is a diagram illustrating a data storage example in the acceleration conversion table 141b for converting the acceleration (estimated value) at the time of impact into an actual measurement value in the second embodiment. As shown in FIG. 6, the acceleration conversion table 141b stores the maximum acceleration at the time of impact calculated by the impact calculation unit 13 as "M1 estimated value" and the minimum acceleration at the time of impact is "M2 estimated value". Is stored as Furthermore, in the acceleration conversion table 141b, these estimated values are associated with the acceleration at impact measured in advance by the high range acceleration sensor as “actual measurement values”. For example, when the estimated M1 value is calculated as “5.10G” and this value is selected as the acceleration at impact, “5.59G” is set as the corresponding actually measured value. 5.59G ″ is used as a comparison target with the threshold value. Similarly, when the M2 estimated value is calculated as “79.70G” and this value is selected as the acceleration at impact, the actually measured value set in advance is “80.57G”. This value is used to determine whether there is a fall. As described above, the acceleration at impact as the M1 estimated value or the M2 estimated value calculated by the impact calculating unit 13 is corrected to an actually measured acceleration value by the application processing unit 14. Note that the M1 estimated value and the M2 estimated value associated with the actual measurement values set in the acceleration conversion table 141b can be updated at any time as in the first embodiment.

  Next, the operation of the portable terminal 10 in the second embodiment will be described. The operation is the same as the operation of the portable terminal 10 in the first embodiment except for the process of calculating the impact time and the acceleration value at the time of the impact, and converting the calculation result into the actual measurement value. Therefore, the same reference numbers are used for common steps, and detailed description thereof is omitted. FIG. 7 is a flowchart for explaining the operation of the portable terminal 10 according to the second embodiment. The operation of the portable terminal 10 according to the second embodiment is the same as the operation of the portable terminal 10 according to the first embodiment, except for steps T9 to T11. Specifically, the processes in S1 to S8 and S11 in FIG. 4 in the first embodiment correspond to the processes in T1 to T8 and T12 in FIG.

  Hereinafter, with reference to FIG. 7 and FIG. 8, the processes of T9 to T11 that are differences from the first embodiment will be described in detail.

As a premise, in FIG. 8, the time t [ms] is defined on the x axis and the acceleration [G] is defined on the y axis, as in the first embodiment. The time t _0, the mobile terminal 10 is a time in contact with the floor to fall. Time t ₃ is the time when the acceleration detected by the sensor unit 11 exceeds the + 4G is a range the upper limit value, the time t ₄ is the time when the sensed acceleration has returned again in Range . Furthermore, the sampling period is set to 1 [ms], the slope held at T7 (the slope between the circles a ₄ a _{5 in} FIG. 8) is set to S _3, and the slope held at T8 (the triangle mark b _{5 in} FIG. 8). between b ₆ inclination) it is referred to as _{S 4.} Since circle a ₆ is acceleration detected by the sensor unit 11 is a sampled value immediately after exceeding the range upper limit (out of range), according acceleration has not been detected in practice, acceleration detected In order to distinguish them from the circles a ₄ and a ₅ representing the sampling values, they are represented by broken lines. Similarly, a triangle mark b ₄ is a sampling value immediately before the acceleration detected by the sensor unit 11 returns to within the range (outside the range), but since such acceleration is not actually detected, the detected acceleration In order to distinguish from the triangle marks b ₅ and b ₆ representing the sampling values, they are represented by broken lines.

  In FIG. 8, a threshold value T <b> 2 that is compared with the actual measurement value in the fall determination is set, but this threshold value T <b> 2 may be a value different from the threshold value T <b> 1 in the first embodiment.

Returning to Figure 7, the T9, the mobile terminal 10 calculates the impact time _{t m.} Since the impact time t _m is an intermediate point between the time t ₃ and the time t ₄ , the following calculation formula (3) is established.

Impact time t _m = (t ₃ + t ₄ ) / 2 (3)

At T10, the portable terminal 10 calculates the maximum value and the minimum value of acceleration at the impact time. Under the above conditions, if the maximum acceleration at the time of impact to be calculated at T10 is M1, there is a relationship of M1 = S ₃ t _m + b and 4 = S ₃ t ₃ + b (b is a constant). The maximum acceleration M1 at time t _m can be calculated by the following mathematical formula (4).

Maximum acceleration upon impact M1 = S ₃ (t ₃ + t ₄ ) / 2 + 4-S ₃ t ₃ = S ₃ (t ₄ −t ₃ ) / 2 +4 (4)

Similarly, under the above conditions, assuming that the minimum acceleration upon impact to be calculated at T10 is M2, the relationship of M2 = S ₄ t _m + b and 4 = S ₄ t ₄ + b (b is a constant) Therefore, the minimum acceleration M2 at time t _m can be calculated by the following mathematical formula (5).

Impact at the minimum acceleration _{M2 = S 4 (t 3 +} t 4) / 2 + 4-S 4 t 4 = S 4 (t 3 -t 4) / 2 +4 ··· (5)

That is, the impact calculation unit 13 obtains the two-dimensional coordinates of the intersection H between the straight line E passing through the circles a ₄ and a ₅ and the straight line G representing the time t = t _m , and the x coordinate value is obtained as the impact time t. _m is estimated, and the y-coordinate value is estimated as the upper limit value M1 of the acceleration range. Similarly, the impact calculation unit 13 obtains a two-dimensional coordinate of an intersection I between the straight line F passing through the triangle marks b ₅ and b ₆ and the straight line G, and estimates the x coordinate value as the impact time t _m . The y coordinate value is estimated as the lower limit value M2 of the acceleration range.

  At T11, the application processing unit 14 converts the acceleration calculated by the impact calculation unit 13 at T10 into an actual measurement value. This conversion process is executed with reference to the acceleration conversion table 141b described above. The conversion from the estimated value to the actually measured value may be performed for both the maximum acceleration M1 and the minimum acceleration M2. However, from the viewpoint of increasing the processing efficiency, the application processing unit 14 calculates one value as the estimated value to be converted. In addition, it is preferable to convert to actual measurement values. For example, when the maximum acceleration at the time of impact calculated by the impact calculation unit 13 at T10 is “5.10”, the estimated value is converted into an actually measured value of “5.59”, and the similar minimum acceleration is “ In the case of 79.80 ", it is converted into an actual measurement value of" 80.68 "(see FIG. 6).

As described above, the portable terminal 10 according to the second embodiment includes the sensor unit 11, the impact calculation unit 13, and the application processing unit 14. The sensor unit 11 detects acceleration within the predetermined range. The impact calculation unit 13 calculates acceleration outside the predetermined range using the acceleration detected by the sensor unit 11. The application processing unit 14 determines whether or not there is a fall using the acceleration calculated by the impact calculation unit 13. More specifically, the impact calculation unit 13 uses the time t ₃ , the time t ₄ , the acceleration gradient S _3, and the acceleration gradient S ₄ to determine the maximum and minimum acceleration values outside the predetermined range. Calculate the value. Time t ₃ is the acceleration detected by the sensor unit 11 is a time in excess of the predetermined range. Time t ₄ is the time at which the acceleration has returned to within the predetermined range. Slope _{S 3} is the slope of the acceleration at time _{t 3} before. The slope S ₄ is the slope of the acceleration after time t ₄ . The application processing unit 14 determines whether or not there is a fall based on whether or not the acceleration calculated by the impact calculation unit 13 is greater than or equal to a predetermined value.

  In other words, the portable terminal 10 according to the second embodiment once calculates a possible range of acceleration at the time of impact, and further calculates an acceleration converted into an actual measurement value as an estimated value from acceleration values that fall within the range. . Therefore, although the acceleration at the time of impact is estimated to be a value between the calculated upper limit value M1 and lower limit value M2, the application processing unit 14 selects any one value from this range or Examples of the calculation method include the following methods. The application processing unit 14 selects the M1 estimated value, which is the maximum acceleration value, as an estimated value to be converted into an actual measurement value. Thereby, the possibility that the actual measurement value ≧ the threshold value is increased, and the portable terminal 10 can increase the probability of being determined to fall. On the contrary, the application processing unit 14 selects the M2 estimated value that is the minimum value of acceleration as an estimated value that is to be converted into an actual value. As a result, the criterion for determining a drop becomes strict, and the possibility that the actual measurement value ≧ the threshold value is relatively reduced. As a result, the portable terminal 10 can suppress the ratio determined as falling and increase the probability that it is determined that there is no falling.

  Alternatively, the application processing unit 14 may calculate an intermediate value between the M1 estimated value and the M2 estimated value and use the calculated result as the estimated value. Thereby, since the portable terminal 10 can set an average estimated value at the time of impact, it can use an actually measured value with no bias as a comparison target with a threshold value when determining the presence or absence of a fall. Further, the application processing unit 14 may set a line segment having both ends of the M1 estimated value and the M2 estimated value, and may use a predetermined ratio value as the estimated value from the M1 estimated value. If the predetermined ratio is, for example, 1/4, the acceleration value at a position close to the M1 estimated value side becomes an estimated value, and the condition for determining a fall is relaxed. Therefore, it is easy to determine that there is a drop. On the other hand, if the predetermined ratio is 3/4, the acceleration value at a position close to the M2 estimated value side becomes an estimated value, and the condition for determining a fall becomes strict. Therefore, it is difficult to determine that there is a drop.

Further, FIG. 8 illustrates an example in which the side exceeding the range (straight line E) takes the maximum acceleration value, and the side returning to the range (straight line F) takes the minimum acceleration value. However, depending on the slope S ₃ before exceeding the range and the slope S ₄ after returning to the range, the straight line E may take the minimum acceleration value and the straight line F may take the maximum acceleration value. In order to cope with such a case, the application processing unit 14 may use an acceleration value close to the estimated value on the side exceeding the range as the estimated value. Specifically, if the estimated value on the side exceeding the range is the maximum estimated value M1, the application processing unit 14 determines the maximum estimated value M1 or a predetermined ratio (for example, 0.1 to 0.4) from the maximum estimated value M1. Is an estimated value to be converted into an actual measurement value. On the other hand, if the estimated value on the side exceeding the range is the minimum estimated value M2, the application processing unit 14 has a predetermined ratio (for example, 0.1 to 0.4) from the minimum estimated value M2 or the minimum estimated value M2. The acceleration value is an estimated value to be converted into an actual measurement value. As a result, the acceleration value that approximates the estimated value on the side where the range has been swung is preferentially used as the estimated value. Therefore, the portable terminal 10 can always use the estimated value closer to the moment of contact with the floor surface for conversion to the actually measured value. As a result, the accuracy of estimation of acceleration at the time of contact with the floor (at the time of impact), and hence the accuracy of drop determination is improved.

Incidentally, in this embodiment, the impact time t _m and the midpoint between the time t ₃ and time t _4, not limited to this, the application processing unit 14, and ends the time t ₃ and time t ₄ set the line, a predetermined ratio (e.g., 0.1 to 0.4) from time _{t 3} may be the time of the impact time _{t m.} As a result, the acceleration value at the time close to the time when the range is exceeded is preferentially used as the estimated value. Therefore, the portable terminal 10 can always use the estimated value closer to the moment of contact with the floor surface for conversion to the actually measured value. As a result, the accuracy of estimation of acceleration at the time of contact with the floor (at the time of impact), and hence the accuracy of drop determination is improved.

In addition, the times t ₁ and t _{2 in the first} embodiment and the times t ₃ and t ₄ in the present embodiment are relative times based on the time t ₀ at the time of contact, respectively. Since it has a clock function, it is possible to specify the actual time when the impact occurred in cooperation with the function. Therefore, the user and the third party can accurately and easily know the date and time when the portable terminal 10 was dropped by referring to this time.

[Drop detection program]
The various processes described in the above embodiments can be realized by executing a prepared program on a computer. Therefore, in the following, an example of a computer that executes a fall determination program having the same function as the portable terminal 10 shown in FIG. 1 will be described with reference to FIG.

  FIG. 9 is a diagram illustrating a computer that executes a fall determination program. As illustrated in FIG. 9, the computer 100 includes a CPU 110, an input device 120, a monitor 130, a voice input / output device 140, a wireless communication device 150, and an acceleration sensor 160. Further, the computer 100 includes a RAM 170 and a data storage device such as a hard disk device 180, which are connected by a bus 190. The CPU 110 executes various arithmetic processes. The input device 120 receives data input from the user. The monitor 130 displays various information. The voice input / output device 140 inputs and outputs voice. The wireless communication device 150 exchanges data with other computers via wireless communication. The acceleration sensor 160 detects acceleration in three axis directions. The RAM 170 temporarily stores various information.

  The hard disk device 180 stores a fall determination program 181 having the same function as the CPU 10a shown in FIG. Further, the hard disk device 180 has drop determination processing related data 182 and a determination history file 183 corresponding to various data (range value, drop determination threshold, acceleration sampling value) stored in the memory 10c shown in FIG. Remembered.

  Then, the CPU 110 reads the drop determination program 181 from the hard disk device 180 and develops it in the RAM 170, so that the drop determination program 181 functions as the drop determination process 171. Then, the fall determination process 171 expands information read from the drop determination processing related data 182 to an area allocated to itself on the RAM 170 as appropriate, and executes various data processing based on the expanded data. Then, the fall determination process 171 outputs predetermined information to the determination history file 183.

  The fall determination program 181 is not necessarily stored in the hard disk device 180, and the computer 100 may read and execute the program stored in a storage medium such as a CD-ROM. . Further, this program may be stored in another computer (or server) connected to the computer 100 via a public line, the Internet, a LAN (Local Area Network), a WAN (Wide Area Network), or the like. In this case, the computer 100 reads the program from these and executes it.

  In each of the above embodiments, the portable terminal 10 corrects the calculation result of the acceleration at impact to an actual measurement value. However, when the sampling period is a predetermined value (for example, 0.1 ms) or less, the impact is detected. The calculation unit 13 can accurately calculate the estimated acceleration value at the time of impact. Therefore, in such a case, the correction process may be omitted.

  In each of the above embodiments, the portable terminal 10 determines that there is a drop when the acceleration in one direction out of the accelerations in the three axial directions is equal to or greater than the threshold value. However, the present invention is not limited to this mode, and the portable terminal 10 estimates out-of-range acceleration for accelerations in a plurality of directions, and among these estimated values, the estimated value in the 2 or 3 axis direction is equal to or greater than a predetermined threshold. For the first time, it may be determined that there is a fall. In this case, the threshold value may be set to a different value for each of the three types of axial directions. Furthermore, the portable terminal 10 estimates out-of-range acceleration for accelerations in a plurality of directions, takes a weighted average of these estimated values, and falls when the estimated value as a result exceeds a predetermined threshold value. It is good also as what determines. In this case, it is not necessary to set individual values for the three types of axial directions, and it is sufficient to set one threshold value for the weighted average estimated value. There are various ways of falling, and acceleration occurs in various directions depending on the way of falling. For this reason, the value of the acceleration in each axial direction that the portable terminal 10 can take upon impact differs depending on the way of dropping. The portable terminal 10 can realize a fall determination based on an acceleration value closer to the actual situation by taking into account not only the acceleration in one direction but also the acceleration in a plurality of axial directions when determining whether or not to fall. As a result, the drop determination accuracy of the portable terminal 10 and the reliability are improved.

Furthermore, regarding the calculation of the inclination, the inclination does not necessarily have to be calculated from adjacent acceleration sampling values. In other words, in the first embodiment, the portable terminal 10 uses the sampling values a ₁ and a ₂ that are adjacent to each other in order to calculate the slope immediately before exceeding the range. Also in the second embodiment, the portable terminal 10 uses the sampling values b ₅ and b ₆ that are adjacent to each other in order to calculate the inclination immediately after the return of the range. However, the portable terminal 10 may calculate the slope value from non-adjacent sampling values. For example, when the sampling period is 1 ms, the mobile terminal 10 calculates the slope of the acceleration value from the sampling values at intervals of 2 ms or 3 ms. It may be a thing.

  In addition, regarding the calculation of the inclination, the portable terminal 10 may calculate a plurality of inclination values every time the range is exceeded or returned, and take an average value thereof. Thereby, the portable terminal 10 estimates acceleration and determines fall based on a more accurate inclination value that suppresses variation (fluctuation) as compared with the case of using one inclination value for each of left and right. It can be performed. As a result, the determination accuracy of the portable terminal 10 and thus the reliability are improved. Furthermore, when calculating the average value of a plurality of inclinations, the portable terminal 10 is estimated to be closer to the actual situation, and an average value (weighting) that is weighted to the inclination value closer to the outside of the range (4G or more). (Average value) can also be taken. Thereby, the variation in inclination is further suppressed, and acceleration estimation and fall determination can be performed based on a more reliable inclination value. As a result, the determination accuracy of the portable terminal 10 and the reliability are further improved.

In addition, in each of the above embodiments, the portable terminal 10 calculates the inclination using at least two sampling values. However, the present invention is not limited to this, and any one sampling value and an overrange or The inclination may be calculated from 4G that is the inclination value at the time of return. Also in this aspect, from the viewpoint of estimating the out-of-range acceleration value with high accuracy, the portable terminal 10 preferably uses a sampling value closer to the outside of the range for the calculation of the inclination. For example, in Example 1 (see FIG. 5), as the combination of the acceleration values (4G) at time _{t 1,} it is preferable to use _{a 2} than the sampling value _{a 1.} Further, for example, in Example 2 (see FIG. 8), it is preferable to use b ₅ rather than the sampling value b ₆ as the combination with the acceleration value (4G) at time t ₄ . Thereby, the portable terminal 10 can estimate the acceleration value using the inclination at the moment when the range is swung and the inclination at the moment when the range is returned. Therefore, the portable terminal 10 can perform the fall determination based on the acceleration value that is closer to the outside of the range. As a result, it is possible to improve the drop determination accuracy. The calculation of the slope value in this manner is not necessarily performed on both the excess side and return side of the range, and may be performed only on either one (for example, the excess range side).

  Further, in each of the above embodiments, the portable terminal 10 refers to the acceleration conversion tables 141a and 141b for conversion from the estimated acceleration value at the time of impact to the actual measurement value, but using a predetermined calculation formula, The actual measurement value may be calculated from the estimated value.

  Furthermore, in each of the above embodiments, taking a fall as an example of a motion with high acceleration, the portable terminal for determining the presence or absence of the fall has been described, but the present invention is not limited to this, throwing on a wall surface, It can also be applied to movements other than dropping, such as collisions with objects. In each of the above embodiments, a mobile phone, a smartphone, and a PDA (Personal Digital Assistant) have been described as portable terminals. However, the present invention is not limited to a portable terminal, and various types of low-range acceleration sensors are provided. It can be applied to various electronic devices.

  Further, each component of the portable terminal 10 shown in FIG. 1 does not necessarily need to be physically configured as illustrated. That is, the specific mode of distribution / integration of each device is not limited to the illustrated one, and all or a part thereof is functionally or physically distributed in an arbitrary unit according to various loads or usage conditions. -It can also be integrated and configured. For example, the sampling processing unit 12, the impact calculation unit 13, and the application processing unit 14 may be integrated as one component. On the other hand, the impact calculation unit 13 may be divided into a part for calculating the inclination immediately before the range excess, a part for calculating the inclination immediately after the range return, and a part for calculating the impact time and the acceleration at that time. Further, regarding the application processing unit 14, the acceleration (estimated value) at the time of impact may be distributed into a part for converting into an actual measurement value and a part for determining whether or not there is a fall. The memory 10c may be connected as an external device of the portable terminal 10 via a network or a cable.

10 Portable terminal 10a CPU
10b Acceleration sensor 10c Memory 10d Display device 10e Wireless device 11 Sensor unit 12 Sampling processing unit 13 Impact calculation unit 14 Application processing units 141a and 141b Acceleration conversion table 100 Computer 110 CPU
120 Input Device 130 Monitor 140 Voice Input / Output Device 150 Wireless Communication Device 160 Acceleration Sensor 170 RAM
171 fall determination process 180 hard disk drive 181 falls determination program 182 fall determination process related data 183 determined history file A antenna B~I straight M acceleration M1 maximum acceleration M2 minimum acceleration T1, T2 threshold _{t 0 ~t 4, t c,} t m Times of Day

Claims (3)

A detection unit for detecting acceleration within a predetermined range;
A calculation unit for calculating an acceleration outside the predetermined range using the acceleration detected by the detection unit;
A drop determination device, comprising: a determination unit that determines whether or not there is a fall using the acceleration calculated by the calculation unit. The calculation unit includes a first time that is a time when the acceleration detected by the detection unit exceeds the predetermined range, a second time that is a time when the acceleration returns to the predetermined range, Using the slope of the acceleration before the first time and the slope of the acceleration after the second time, calculate an acceleration outside the predetermined range,
The fall determination device according to claim 1, wherein the determination unit determines whether or not there is a fall based on whether the acceleration calculated by the calculation unit is equal to or greater than a predetermined value. A drop determination device that detects a predetermined range of acceleration,
Detecting acceleration within the predetermined range;
Using the detected acceleration, calculate an acceleration outside the predetermined range,
A fall determination method, wherein the presence or absence of fall is determined using the calculated acceleration.

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