JP5995319B2 - Portable terminal, program and method for determining vertical downward direction during walking using geomagnetism - Google Patents

Description

  The present invention relates to a technique for determining a traveling direction of a pedestrian using a sensor carried by the pedestrian. In particular, the present invention relates to an autonomous navigation technique for deriving a pedestrian travel direction in real time.

  2. Description of the Related Art Conventionally, an autonomous navigation technique for deriving a current position and a traveling direction in real time using a sensor such as an acceleration sensor installed on a moving subject has been actively used. For example, a car navigation system that is currently widely used is realized by combining this autonomous navigation technology and GPS (Global Positioning System) technology. In the car navigation system, an accurate current position and traveling direction and travel route information to the destination are displayed and notified to the driver of the car.

  This car navigation system corrects the current position information measured by the GPS technology by an autonomous navigation technology using a vehicle speed pulse or a gyro. In addition, for example, by using the map matching technique based on the projection method disclosed in Patent Document 1, the reference road map information is read out as necessary, so that the travel route does not deviate from the road position due to the measurement error of the sensor. Correct the position and direction of travel.

  Further, such navigation technology is also applied to a portable terminal possessed by a pedestrian. For example, Patent Document 2 discloses a portable terminal that derives the current position by accumulating the detected “number of steps” and the “step length” of the pedestrian from the walking start position. In this way, when the autonomous navigation technique is applied to a pedestrian, components other than the horizontal direction component are also detected for acceleration. Therefore, the walking distance is derived not from simple integration of the output value of the acceleration sensor but from “number of steps” and “step length”.

Here, the “number of steps” is a step between a peak and a peak in the time change of the magnitude of acceleration (√ (a _x ² + a _y ² + a _z ² )) measured by the acceleration sensor mounted on the mobile terminal. It is counted (see, for example, Patent Document 3). On the other hand, the “step length” is preset by the user or estimated from the height of the user. Alternatively, there is a technique for calibrating the “step length” by causing a pedestrian to walk a specified distance (see, for example, Non-Patent Document 1).

  Further, the traveling direction is detected using an azimuth sensor using a geomagnetic sensor or the like. For example, Patent Document 4 discloses a technique for determining a pedestrian's traveling direction using the relationship between vertical acceleration and traveling direction acceleration after determining the vertical direction to derive the terminal posture. Yes. Patent Document 5 discloses a technique for determining a traveling direction from the attitude of a terminal at a specific time. Further, Patent Documents 6 and 7 disclose techniques for determining a traveling direction based on a horizontal acceleration distribution. Furthermore, Patent Document 8 discloses a technique for determining the traveling direction from the characteristics of a pedestrian's arm swing.

  As an invention of the same applicant as the present application, Patent Document 9 discloses that an azimuth reference plane defined by a normal vector (direction reference vector) of an acceleration plane defined by arm swing motion, a gravity vector, and a geomagnetic vector. A technique for calculating the azimuth angle in the traveling direction from the normal vector (azimuth reference vector) is disclosed. Patent Document 10 discloses a technique for determining the direction of travel using acceleration data in the swing phase during walking.

JP-A-5-061408 Japanese Patent Laid-Open No. 9-089584 Japanese Patent Laying-Open No. 2005-038018 JP 2008-039619 A WO2006 / 104140 Japanese Patent No. 4126388 JP 2008-116315 A JP 2010-271167 A JP 2010-008103 A JP 2012-168004 A

“Nike + iPod User's Guide”, page 27, [online], [searched on December 27, 2012], Internet <URL: http://manuals.info.apple.com/en/nikeipod_users_guide.pdf>

  However, in the related art as described above, when a pedestrian wears a portable terminal such as by inserting it into a pocket of trousers, the direction related to progress (walking motion), for example, vertically downward or the direction of travel It was difficult to determine accurately.

  For example, the technique described in Patent Document 4 assumes that the posture of a mobile terminal worn by a pedestrian is approximately constant, and determines the direction in which acceleration exceeding a predetermined threshold is detected as the traveling direction. Candidate for Further, the techniques described in Patent Documents 5, 6, and 7 also assume that the posture of the mobile terminal worn by the pedestrian is approximately constant, and the horizontal direction detected during walking is the same. The direction of travel is determined from the acceleration distribution.

  However, in practice, the posture of the mobile terminal worn by the pedestrian is not necessarily constant. For this reason, even if the direction in which the acceleration exceeding the predetermined threshold is detected as in the technique of Patent Document 4, the direction is often not the traveling direction. Further, even when the traveling direction is obtained from the horizontal acceleration distribution as in the techniques of Patent Documents 5, 6, and 7, the direction is often not the traveling direction.

  Furthermore, the techniques described in Patent Documents 8 and 9 determine the traveling direction by detecting the movement of the hand (arm) of a pedestrian holding the mobile terminal, and the mobile terminal performs arm swing motion. It is assumed that it moves with it. Therefore, when the pedestrian is walking with the portable terminal inserted into, for example, a pants pocket, the traveling direction cannot be determined.

  In addition, the technique described in Patent Document 10 certainly determines the traveling direction when the pedestrian has inserted the mobile terminal into the pants pocket. However, when the posture of the mobile terminal fluctuates during walking, an error is included in the direction of the calculated gravitational acceleration vector, and the accuracy in the determined traveling direction may be deteriorated.

  Therefore, the present invention more accurately indicates the direction related to the progress, for example, the vertically downward direction or the traveling direction, even when the pedestrian is wearing the portable terminal in the pocket of the pants. An object is to provide a portable terminal, a program, and a method that can be determined.

According to the present invention, an acceleration sensor capable of measuring acceleration as a vector quantity and a geomagnetic sensor capable of measuring geomagnetism as a vector quantity are provided, and the terminal is carried based on the measured acceleration vector A and geomagnetic vector M. A mobile device that determines an orientation related to a user's progress,
Stationary determination means for determining whether or not the mobile terminal is stationary;
A stationary acceleration direction determining means for determining a stationary acceleration direction that is a direction of an acceleration vector A when it is determined that the portable terminal is stationary in a terminal coordinate system fixed to the portable terminal;
Geomagnetic vertical component determining means for determining a geomagnetic vertical component M _GS is a projection component to the resting acceleration direction of the geomagnetic vector M in time of determination that the mobile terminal is stationary has been performed,
A geomagnetism projection component calculating means for calculating a geomagnetism projection component _MGW , which is a projection component of the geomagnetism vector M at each time point in the direction of acceleration at rest;
By comparing the calculated geomagnetic projection component _MGW with the determined geomagnetic vertical component _MGS , the vertical stationary time is determined, which is the time when the acceleration direction at rest can be determined vertically downward. A portable terminal having a time point determination unit is provided.

As an embodiment of the vertical stationary time point determining means of the portable terminal, the vertical stationary time point determining means includes a time point when the calculated geomagnetic projection component _MGW coincides with the determined geomagnetic vertical component _MGS or within a predetermined range. Or a time point having a smaller absolute value of the difference among adjacent time points having different signs of the difference between the geomagnetic projection component _MGW and the geomagnetic vertical component _MGS is determined as a vertical stationary time point. It is also preferable.

Further, as an embodiment of the mobile terminal according to the present invention, the mobile terminal includes an acceleration time change calculating means for calculating one acceleration component or acceleration magnitude in the acceleration vector A at each time point;
Based on the maximum point or minimum point in the time change of the acceleration component or the magnitude of acceleration, the user's walking cycle, the stance phase in which the user's feet are on the ground, or the user's feet away from the ground before Relative rest time calculation that detects the swing phase that is being carried to and calculates the relative rest time that is the relative position of the determined vertical rest time within the walking cycle, stance phase, or swing phase And further comprising means
It is also preferable that the vertical stationary time point determination means determines the vertical stationary time point using periodically stationary relative stationary time points.

Further, in the above-described embodiment using the relative stationary time point, the vertical stationary time point determining means includes the calculated geomagnetic projection component M _GW and the determined geomagnetic field only during a predetermined measurement time including the periodically occurring relative stationary time point. It is also preferable to compare the vertical component _MGS .

Furthermore, in the above-described embodiment using the relative stationary time point, the vertical stationary time point determining unit calculates the geomagnetic projection component M _GW and the geomagnetic vertical component M _GS for a predetermined period after the relative stationary time point calculating unit calculates the relative stationary time point. It is also preferable to determine the relative stationary time point that occurs periodically instead of the vertical stationary time point.

As another embodiment of the portable terminal according to the present invention, the portable terminal includes an acceleration time change calculating means for calculating one acceleration component or acceleration magnitude in the acceleration vector A at each time point;
Based on the maximum or minimum point in the time change of the acceleration component or the magnitude of the acceleration, the stance phase in which the user's foot is on the ground, or the user's foot is carried away from the ground A right / left-facing vector that detects a free leg period, which is a period, and calculates a right / left-facing vector U indicating the right or left direction of the user facing the traveling direction from a plurality of acceleration vectors A in the stance or swing leg period A calculation means;
A gravitational acceleration vector G is calculated based on the acceleration vector A when it is determined that the mobile terminal is stationary, and the gravitational acceleration vector G and the geomagnetic vector M at the time of vertical stationary are calculated. It is also preferable to further include a progress-related direction determination means for determining a travel direction at the time of vertical rest from the right / left direction vector U.

  Further, in the above embodiment using the right / left direction vector U, the right / left direction vector calculating means calculates the right / left direction vector U by taking the outer product of the acceleration vectors A at the start and end times of the stance phase or the swing phase. It is also preferable to calculate.

  Furthermore, in the above embodiment using the right / left direction vector U, the right / left direction vector calculating means determines an acceleration plane caused by the user's walking motion from a plurality of acceleration vectors A in the stance phase or the swing phase, and accelerates the acceleration. It is also preferable to calculate the right / left direction vector U as the normal vector of the surface.

Moreover, as other embodiment of the portable terminal by this invention,
Calculates a gravitational acceleration vector G based on the acceleration vector A at the time the determination of the mobile terminal is stationary has been performed, from the the gravitational acceleration vector G, the geomagnetic vector M of the vertical stationary point, North Calculating a north / south direction acceleration vector that is a direction or south direction vector and an east / west direction acceleration vector that is an east direction or west direction vector, and determining a group of horizontal acceleration components acquired for each walking cycle;
Calculate variances Vxx, Vyy and covariance Vxy in a group of horizontal acceleration components, and calculate an eigenvalue λ based on these variances and covariances;
The eigenvector [e ₁ , e ₂ ] is calculated using the eigenvalue λ, and the angle Tan ⁻¹ (e ₁ / e ₂ ) calculated from the calculated eigenvector [e ₁ , e ₂ ] is determined in the traveling direction. It is also preferable to further include a progress-related direction determining means.

The present invention further includes an acceleration sensor capable of measuring acceleration as a vector quantity and a geomagnetic sensor capable of measuring geomagnetism as a vector quantity, and the terminal is determined based on the measured acceleration vector A and geomagnetic vector M. A program for causing a computer mounted on a mobile terminal to determine a direction related to the progress of a user who has carried it,
Stationary determination means for determining whether or not the mobile terminal is stationary;
A stationary acceleration direction determining means for determining a stationary acceleration direction that is a direction of an acceleration vector A when it is determined that the portable terminal is stationary in a terminal coordinate system fixed to the portable terminal;
Geomagnetic vertical component determining means for determining a geomagnetic vertical component M _GS is a projection component to the resting acceleration direction of the geomagnetic vector M in time of determination that the mobile terminal is stationary has been performed,
A geomagnetism projection component calculating means for calculating a geomagnetism projection component _MGW , which is a projection component of the geomagnetism vector M at each time point in the direction of acceleration at rest;
By comparing the calculated geomagnetic projection component _MGW with the determined geomagnetic vertical component _MGS , the vertical stationary time is determined, which is the time when the acceleration direction at rest can be determined vertically downward. A program for a portable terminal that causes a computer to function as time determination means is provided.

Further, according to the present invention, the direction related to the progress of the user carrying the mobile terminal including the acceleration sensor capable of measuring acceleration as a vector quantity and the geomagnetic sensor capable of measuring geomagnetism as a vector quantity is determined. A method for determining a travel-related direction that is determined based on a measured acceleration vector A and geomagnetic vector M,
A first step of determining whether or not the mobile terminal is stationary;
The stationary acceleration direction determining means determines the stationary acceleration direction, which is the direction of the acceleration vector A when it is determined that the portable terminal is stationary in the terminal coordinate system fixed to the portable terminal. A second step;
The third step is geomagnetic vertical component determining means, for determining a geomagnetic vertical component M _GS is a projection component to the resting acceleration direction of the geomagnetic vector M in time of determination that the mobile terminal is stationary has been performed When,
Geomagnetic projection component calculating means, and a fourth step of calculating geomagnetic projection component M _GW is a projection component to the resting acceleration direction of the geomagnetic vector M at each time point,
The vertical stationary time determination means compares the calculated geomagnetic projection component M _GW with the determined geomagnetic vertical component M _GS to determine the vertical acceleration time at which the stationary acceleration direction can be determined vertically downward. A progression related orientation determination method is provided having a fifth step of determining a stationary time point.

  According to the mobile terminal, the program and the method of the present invention, even when a pedestrian is wearing the mobile terminal such as inserting the mobile terminal into a pants pocket, the direction related to progress, for example, vertically downward or The traveling direction can be determined more accurately. In particular, when the pedestrian carries the mobile terminal in a form that can be worn on the lower body part of the pedestrian, the vertical downward direction or the traveling direction can be determined more accurately.

It is explanatory drawing which shows the aspect which a user walks in the state which inserted the portable terminal by this invention in the pocket of the lower body. It is a functional block diagram which shows one Embodiment of the portable terminal by this invention. It is a graph for _{demonstrating} the method to determine the geomagnetic vertical component _MGS and the geomagnetic projection component MGW of the geomagnetic vector M in a terminal coordinate system. Graph showing time change of acceleration component during walking, graph showing time change of angle (cosine) made by stationary acceleration unit vector e _GS with respect to vertical downward direction, geomagnetic projection component M _GW changing time, geomagnetic vertical It is a graph which shows the relationship with component _MGS . It is a vector diagram for demonstrating the method of determining the advancing direction of the user who walks from the determined perpendicular downward (gravity acceleration vector). It is the schematic for demonstrating the relationship between angle (alpha) and azimuth angle (theta).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view showing a mode in which a user walks with a portable terminal according to the present invention inserted in a pocket on the lower body.

  According to FIG. 1, the user (pedestrian) is walking with the portable terminal 1 according to the present invention inserted in the pocket of the lower body (trousers). In this state, the posture of the mobile terminal 1 is not constant and varies depending on the walking motion. In this state, the pedestrian is not operating the portable terminal 1, but the portable terminal 1 itself activates some application to detect the traveling direction of the pedestrian.

  The mobile terminal 1 incorporates an “acceleration sensor” capable of measuring acceleration as a vector quantity and a “geomagnetic sensor” capable of measuring geomagnetism as a vector quantity in a form fixed to the terminal. For this reason, according to the direction of the portable terminal 1, the triaxial coordinate system in these sensors is uniquely determined. Therefore, hereinafter, this sensor coordinate system is referred to as a “terminal coordinate system”. The “terminal coordinate system” is represented as an xyz coordinate system in FIG. In addition to the “terminal coordinate system”, the mobile terminal 1 has a “walking coordinate system” with the pedestrian's traveling direction as the forward direction, with forward-backward, rightward-leftward, vertical upward-vertically downward axes. Is also set.

  Here, the “walking coordinate system” varies with respect to the mobile terminal 1 in response to the mobile terminal 1 changing its posture while walking. In addition, since the relationship between the “terminal coordinate system” and the “walking coordinate system” at a predetermined point in the walking cycle is determined depending on the orientation in which the mobile terminal 1 is inserted into the pocket of the pants, it is assumed in advance. Can not do it.

  Under such circumstances, the mobile terminal 1 can more accurately determine “vertical downward”, which is one direction related to progression (walking motion) in the “walking coordinate system”. Furthermore, the “traveling direction” of the pedestrian can be derived more accurately based on the accurately determined “vertical downward”.

In order to determine such an accurate “vertical downward”, the mobile terminal 1
(A) In the “terminal coordinate system”, determine the “acceleration direction at rest”, which is the direction of the acceleration vector A when determining whether the mobile terminal 1 is stationary,
(B) determining “geomagnetic vertical component M _GS ”, which is a projection component of the geomagnetic vector M to the “stationary acceleration direction” at the time of determining whether the mobile terminal 1 is stationary;
(C) calculating “geomagnetic projection component M _GW ” that is a projection component of the geomagnetic vector M at each time point to the “stationary acceleration direction”;
(D) By comparing the calculated “geomagnetic projection component M _GW ” with the determined “geomagnetic vertical component M _GS ”, it is possible to determine “the acceleration direction at rest” as “vertically downward”. The “vertical stationary time point” that is the time point is determined.

Here, the “acceleration direction at rest” in the “terminal coordinate system” is exactly vertically downward at the time of stillness determination. Further, the geomagnetic vector M is generally measurable at one point on the earth at each time point, and is an absolute orientation reference. Therefore, by comparing the “geomagnetic projection component M _GW ” with the determined “geomagnetic vertical component M _GS ”, that is, by measuring the geomagnetic vector M, the “stationary acceleration direction” is the time point when the “downward acceleration direction” becomes vertically downward. The “vertical stationary time” can be determined.

  In addition, in embodiment shown in FIG. 1, although the portable terminal 1 is the state inserted in the pocket of the pedestrian's trousers, naturally it is not limited to this state. For example, it is also preferable that the mobile terminal 1 is carried in a form that is mounted and inserted into any part of the lower body of the pedestrian. In particular, it is also preferable that the mobile terminal 1 is mounted and inserted at a position close to one of the left and right legs of the pedestrian.

[Mobile terminal 1]
FIG. 2 is a functional configuration diagram showing an embodiment of the mobile terminal 1 according to the present invention.

  According to FIG. 2, the portable terminal 1 includes an acceleration sensor 100, a geomagnetic sensor 101, a display unit 102, and a processor memory. Here, the processor memory realizes its function by executing a program. The mobile terminal 1 preferably further includes a positioning unit 103.

  In addition, the processor memory includes, as functional components, a stationary determination unit 110, a stationary acceleration direction determination unit 111, a geomagnetic vertical component determination unit 112, a geomagnetic projection component calculation unit 113, and a vertical stationary time point determination unit 114. , Acceleration time change calculation / accumulation unit 115, relative stationary time calculation unit 116, travel-related direction determination unit 117, right / left vector calculation unit 118, map information storage unit 119, and display control unit 120. .

  The acceleration sensor 100 is an acceleration measuring unit that can measure acceleration as a vector quantity. For example, the acceleration sensor 100 is formed by using, for example, a MEMS (Micro Electro Mechanical Systems) technology, and is a triaxial type using a capacitance method or a piezoresistive method. It can be an accelerometer.

  The geomagnetic sensor 101 is a magnetic measurement unit capable of measuring geomagnetism as a vector quantity, and uses, for example, a magnetoresistance (AMR, GMR, or TMR) effect, a magnetic impedance (MI) effect, a fluxgate (FG) method, or a Hall effect. Thus, a three-axis type geomagnetic meter that measures geomagnetism can be obtained.

  The stationary determination unit 110 determines whether or not the mobile terminal 1 is stationary. This stillness determination can be performed by various methods. Several embodiments will be described below.

<Stillness judgment based on difference between maximum and minimum acceleration>
Stillness determination time is for T _1, during which time T _1, the acceleration vector A is measured n times, 3n pieces of acceleration data which is an acceleration component in each axis direction in the terminal xyz coordinate system, i.e.,
A _xi , A _yi , and A _zi (i = 1, 2,..., N)
Is sampled. Here, the sampling time Δt is (T ₁ / n). T ₁ is set to 1.0 sec (seconds), for example.

For each of the sampled n A _xi , n A _yi , and n A _zi , the n data are compared and the maximum and minimum values are determined as follows.
Maximum value of acceleration x-axis direction component within time T ₁ : maxA _x
Minimum value of acceleration x-axis direction component within time T ₁ : minA _x
Maximum value of acceleration y-axis direction component within time T ₁ : maxA _y
Minimum value of acceleration y-axis direction component within time T ₁ : minA _y
Maximum value of acceleration z-axis direction component within time T ₁ : maxA _z
Minimum value of acceleration z-axis direction component within time T ₁ : minA _z

Here, assuming that the predetermined threshold values are φ _x , φ _y, and φ _z , the maximum value and the minimum value are the following conditional expressions (1a) maxA _x −minA _x <φ _x ,
(1b) maxA _y −minA _y <φ _y and (1c) maxA _z −minA _z <φ _z
If satisfying, determines at time T _1, the mobile terminal 1 was at rest, and. The threshold _values φ _x , φ _y and φ _z are set to 0.5 (m / s ² ), for example.

<Stillness judgment by standard deviation of acceleration>
First, as in the above-described method, the acceleration is measured n times during the stationary determination time T ₁ , and 3n pieces of acceleration data A _xi , A _yi , and A _zi (i = 1, 2,..., n). Then, the magnitude of acceleration | A | _{i is changed} to | A | _i = ((A _xi ) ² + (A _yi ) ² + (A _zi ) ² ) ^0.5
And the average of the acceleration magnitudes | A | _i (i = 1, 2,..., N)
av | A | = (| A | ₁ + | A | ₂ +... + | A | _n ) / n
And

Next, from these values, the standard deviation σ _{acc of} acceleration is calculated using the following equation.
σ _acc = (Σ (| A | _i −av | A |) ² / n) ^0.5
Here, Σ is a summation from i = 1 to i = n.

Here, assuming that the predetermined threshold is S, the obtained standard deviation σ _acc is _expressed by the following conditional expression (2) σ _acc <S
If satisfying, determines at time T _1, the mobile terminal 1 was at rest, and. The threshold S is set to 0.22 (m / s ² ), for example. In the stationary determination described above, it is naturally possible to perform the stationary determination using the variance V _acc = Σ (| A | _i −av | A |) ² / n instead of the standard deviation σ _acc. .

<Stillness determination based on variance of each axial component of acceleration>
First, as described above, 3n pieces of acceleration data A _xi , A _yi , and A _zi (i = 1, 2,..., N) are acquired by measurement at the stillness determination time T ₁ . Next, variances V _x , V _y, and V _z for each axial component of acceleration are calculated as follows.
(3a) V _x = Σ (A _xi −avA _x ) ² / n
_{(3b) V y = Σ (} A yi -avA y) 2 / n
(3c) V _z = Σ (A _zi -avA _z ) ² / n
Here, avA _x is an average value of A _xi (i = 1, 2,..., N), and avA _y and avA _z are the same. Σ is a summation from i = 1 to i = n.

Next, assuming that the predetermined threshold is Th ₀ , the obtained dispersion is expressed by the following conditional expression (4) V _x <Th ₀ , V _y <Th ₀ , and V _z <Th _0.
If satisfying, the time T _1, the mobile terminal 1 was at rest, and determines. The threshold value Th ₀ is set to 0.05 (m ² / s ⁴ ), for example. In the stationary determination described above, it is natural that the stationary determination is performed using the standard deviations σ _x , σ _y, and σ _z that are the square roots of these variances instead of the variances V _x , V _y, and V _z. Is possible.

  The stationary determination unit 110 performs the stationary determination by the method as described above, and outputs the determination result to the stationary acceleration direction determination unit 111 and the geomagnetic vertical component determination unit 112.

The stationary acceleration direction determination unit 111 is based on the direction of the acceleration vector A (“stationary acceleration vector”) when the stationary determination unit 110 performs the stationary determination in the terminal coordinate system fixed to the mobile terminal 1. Determine a certain acceleration direction at rest. Specifically, it is also preferable to determine the stationary acceleration unit vector e _GS as the unit vector of the “static acceleration vector”. Note that the “stationary acceleration vector” is an average vector of the acceleration vectors A acquired by the measurement at the stationary determination time T ₁ at the time of stationary determination, and the unit vector of such a “static acceleration vector” is the stationary acceleration. The unit vector e _GS is also preferable. Next, the stationary acceleration direction determining unit 111 outputs the determined stationary acceleration unit vector e _GS (having the stationary acceleration direction) to the geomagnetic vertical component determining unit 112 and the geomagnetic projection component calculating unit 113.

The geomagnetic vertical component determination unit 112 is a geomagnetic vertical component M, which is a projection component of the geomagnetic vector M onto the stationary acceleration direction (stationary acceleration unit vector e _GS ) when the stationary determination unit 110 performs the stationary determination. Determine _GS . Further, it outputs the determined geomagnetic vertical component M _GS vertically stationary point determining unit 114.

Geomagnetic projection component calculation unit 113 calculates the geomagnetic projection component M _GW is a projection component to the resting acceleration direction of the geomagnetic vector M (resting acceleration unit vector e _GS) at each time point. Further, the calculated geomagnetic projection component _MGW is output to the vertical stationary time determination unit 114.

The vertical stationary time point determination unit 114 compares the calculated geomagnetic projection component M _GW with the determined geomagnetic vertical component M _GS to obtain a “vertical stationary time point”, which is a time point when the acceleration vector A is vertically downward. decide. Specifically, the calculated geomagnetic projection component _MGW and the determined geomagnetic vertical component _MGS coincide with each other or have a difference within a predetermined range, or the geomagnetic projection component _MGW and the geomagnetic vertical component _MGS. It is also preferable that a time point having a smaller absolute value of the difference among adjacent time points having different signs from each other is determined as a “vertical stationary time point”. Further, the determined “vertical stationary time point” is output to the travel-related direction determination unit 117.

The acceleration time change calculation / accumulation unit 115 calculates one acceleration component or acceleration magnitude in the acceleration vector A at each time point. here,
(A) It is also preferable to calculate an acceleration projection component A _V that is a projection component of the acceleration vector A at each time point to a stationary acceleration direction (stationary acceleration unit vector e _GS ). Or
(B) The magnitude | A | (the square root of the sum of squares of each axis component) of the acceleration vector A at each time point may be calculated.

The acceleration time variation calculation and storage unit 115 accumulates the magnitude of the acceleration component (acceleration projection component A _V) or acceleration calculated at each time point, the acceleration component as a function of time (acceleration projection component A _V) or It is also preferable to output the acceleration magnitude data to the relative stationary time point calculation unit 116, the travel-related direction determination unit 117, and the right / left vector calculation unit 118.

  The progression-related direction determination unit 117 determines the “static vector at rest” as a vertically downward vector (that is, a gravitational acceleration vector). Further, the determined geomagnetic vector M at the “vertical stationary time” is determined as a vector in the direction of geomagnetism. Furthermore, it is also preferable that the acceleration direction at rest at the determined “vertical stationary time point” is determined to be vertically downward.

The relative stationary time point calculation unit 116 calculates the walking cycle of the pedestrian (user) based on the acceleration component (acceleration projection component A _V ) or the maximum point (maximum point as a function of time) in the temporal change in the magnitude of acceleration. Detecting a stance phase in which the pedestrian's feet are on the ground, or a swing phase in which the pedestrian's feet are carried forward away from the ground, within the walking cycle, in the stance phase or A “relative stationary time point” that is a relative position of the determined “vertical stationary time point” within the swing period is calculated. The “relative stationary time point”, the stance phase and the free leg phase will be described in detail later with reference to FIG.

  It is also preferable that the progress-related direction determination unit 117 that has input the “relative stationary time point” determines the vertical stationary time point using periodically generated relative stationary time points.

When the “relative stationary time point” is adopted, the vertical stationary time point determination unit 114 determines the calculated geomagnetic projection component M _GW only during a predetermined measurement time including the “relative stationary time point” that occurs periodically. It is also preferable to compare the calculated geomagnetic vertical component _MGS . Further, the vertical stationary time point determination unit 114 periodically performs a predetermined period after the relative stationary time point calculation unit 116 calculates the “relative stationary time point” without depending on the geomagnetic projection component M _GW and the geomagnetic vertical component M _GS. It is also preferable to determine the “relative stationary time point” occurring at “vertical stationary time point”.

The right / left vector calculation unit 118 detects the stance phase or the swing phase based on the acceleration component (acceleration projection component A _V ) or the maximum point in the temporal change in the magnitude of the acceleration, and detects the stance phase or the swing phase. From the acceleration vector A, a right / left direction vector U indicating the right or left side of the pedestrian facing in the traveling direction is calculated. In particular,
(A) It is also preferable to calculate the right / left direction vector U by taking the outer product of the acceleration vectors A at the start and end times of the stance phase or the swing phase. Or
(B) It is also preferable to determine an acceleration plane generated by the walking motion of the pedestrian from a plurality of acceleration vectors A in the stance phase or the swing phase and calculate the right / left direction vector U as a normal vector of the acceleration plane.

The progression-related direction determination unit 117 that has input the right / left direction vector U
(A) gravity acceleration vector G;
(B) the geomagnetic vector M at the “vertical stationary point”;
(C) The traveling direction at the “vertical stationary time point” is determined from the calculated right / left direction vector U.

Further, as a change mode, the progress-related direction determination unit 117 uses the acceleration vector at rest determined as the vertical downward direction as the gravitational acceleration vector G,
(A) A horizontal acceleration acquired at every step or every walking cycle by calculating a north / south direction acceleration vector and an east / west direction acceleration vector from the gravitational acceleration vector G and the geomagnetic vector M at the time of vertical stationary. Determine a group of vectors,
(B) calculating variances Vxx, Vyy and covariance Vxy in a group of horizontal acceleration vectors, and calculating an eigenvalue λ based on these variances and covariances;
(C) The eigenvector [e ₁ , e ₂ ] is calculated using the eigenvalue λ, and the angle Tan ⁻¹ (e ₁ / e ₂ ) calculated from the eigenvector [e ₁ , e ₂ ] is set in the traveling direction. It is also preferable to determine.

  Note that the method of determining the traveling direction using the right / left direction vector U or using the variance in the group of horizontal acceleration vectors described above will be described in detail later with reference to FIG.

  The map information storage unit 119 accumulates map information, and outputs map information corresponding to the location of the mobile terminal 1 designated by the display control unit 15 to the display control unit 15.

  The positioning unit 103 captures a positioning radio wave from a GPS satellite, and further measures the location (latitude, longitude) of the mobile terminal 1 by a GPS positioning method. The location information is output to the display control unit 120.

  The display control unit 120 inputs the traveling direction data from the traveling-related direction determination unit 117 and the location information from the positioning unit 103. Also, the location information is output to the map information storage unit 119, and map information regarding the location is acquired. Next, the display control unit 15 displays the location on the map and generates an image in which the traveling direction is indicated by an arrow or the like. This image is output to the display unit 102.

  The display unit 102 is, for example, a display unit, displays an image input from the display control unit 15, and performs navigation (route guidance) for a user (pedestrian) walking with the mobile terminal 1.

[The geomagnetic vertical component _MGS and the geomagnetic projection component _MGW ]
Figure 3 is a graph for explaining a method of determining the geomagnetic vertical component M _GS and geomagnetic projection component M _GW of the geomagnetic vector M in the terminal coordinate system.

  FIG. 3A shows a terminal coordinate system and a walking coordinate system when the pedestrian is stationary. As this terminal coordinate system, for example, when the screen of the mobile terminal 1 is viewed in the vertical direction, the x axis is the axis from the upper side to the lower side of the mobile terminal 1, and the y axis is the left side to the right side of the mobile terminal 1. The z axis is defined as the axis from the back side of the mobile terminal 1 to the front side. Of course, the setting of the terminal coordinate system is not limited to this.

  In addition to this terminal coordinate system, the mobile terminal 1 is also set with a walking coordinate system having forward-backward, rightward-leftward, vertical upward-vertical downward axes, with the pedestrian's traveling direction as forward. .

First, the stationary acceleration direction (stationary acceleration unit vector e _GS ) is determined. The direction in the terminal coordinate system (xyz coordinate system) of the acceleration vector A (stationary acceleration vector) measured by the acceleration sensor 100 (FIG. 2) at the time of stationary determination (by the stationary determination unit 110 (FIG. 2)) Acceleration direction. Furthermore, the acceleration unit vector e _GS at rest which is a unit vector in this direction, that is,
(5) e _GS = (e _Gx , e _Gy , e _Gz )
Is calculated. The stationary acceleration unit vector e _GS is then held as a reference for determining the vertical downward direction.

Next, the geomagnetic vertical component M _GS in the geomagnetic vector M = (M _x , M _y , M _z ) measured by the geomagnetic sensor 101 (FIG. 2) at the time of stationary determination (by the stationary determination unit 110 (FIG. 2)) equation _{(6) M GS = e Gx} × M x + e Gy × M y + e Gz × M z
Calculate using. As shown in the above equation (6), the geomagnetic vertical component M _GS is a projection component of the geomagnetic vector M to the stationary acceleration unit vector e _GS at the time of stationary determination.

  FIG. 3B shows a geomagnetic vector M in the terminal coordinate system when the user is walking. Note that the walking coordinate system fluctuates with respect to the terminal coordinate system (mobile terminal 1) in response to the mobile terminal 1 changing its posture while walking (not shown). Similarly, in the terminal coordinate system, the geomagnetic vector M varies with walking.

Here, in each (sampling) moment, a geomagnetic vector _{M = (m x, m y} , m z) geomagnetism projection component M _GW is a projection component to the resting acceleration unit vector e _GS of the following formula (7) _{M GW = e Gx × m x} + e Gy × m y + e Gz × m z
Calculate using.

The “vertical stationary time point” is determined by comparing the geomagnetic projection component M _GW calculated at each time point with the geomagnetic vertical component M _GS .

[Determination of vertical stationary time]
FIG. 4A is a graph showing temporal changes in acceleration components during walking. FIG. 4B is a graph showing the time change of the angle (cosine) formed by the acceleration unit vector e _GS at rest with respect to the downward vertical direction. Further, FIG. 4C is a graph showing the relationship between the time-varying geomagnetic projection component _MGW and the geomagnetic vertical component _MGS .

First, at each time point, the acceleration projection component A _V of the acceleration vector A = (A _x , A _y , A _z ) measured by the acceleration sensor 100 (FIG. 2) is expressed by the following equation (8) A _V = e _Gx × A _x + e _Gy × A _y + e _Gz × A _z
Calculate using. Thus, the acceleration projection component _AV is a projection component of the acceleration vector A onto the stationary acceleration unit vector _eGS .

As shown in FIG. 4 (A), in the time variation of the acceleration projection component A _V, small (one-step) and variation, large (one-step) and fluctuations are observed alternately. Such a variation is observed not only in the acceleration projection component _AV but also in the magnitude | A | (the square root of the sum of squares of each axis component) of the acceleration A. It is also possible to carry out the method described below using the size.

A period in which the observed small (one step) variation and large (one step) variation are combined corresponds to a “walking cycle”. “Walking cycle” is the time from the initial grounding to the next initial grounding on the foot on the same side as the mobile terminal 1, and this time is divided into “Standing period” and “Free leg period” as follows: Is done.
“Standing period”: The period when the foot is on the ground “Swinging period”: The period when the foot is off the ground and carried forward by the swing

For example, attention is paid to the leg on the side of the pocket (of the pants) in which the mobile terminal 1 is inserted. Here, the leg on the side of the pocket is on the ground during the “stance phase”, and the leg on the side of the pocket is carried forward in the “free leg period”. In the “Standing Period”, the movement of the foot (leg) is small, and in the “Left Period”, the movement of the foot (leg) is large. In addition, when a person walks, the left and right feet are alternately carried forward, so that the “stance phase” and the “free leg phase” are alternately repeated. As a result of such walking, the time change of the acceleration projection component A _V, small (one-step) and variation (one step) large is the change and are observed alternately.

As shown in FIG. 4 (A), the graph of the acceleration projection component A _V, the maximum point of the smaller A _V value (maximum point (small)), the maximum point of the large A _V value (local maximum point (large)) Appear alternately. Here, the “walking cycle” is a period from one local maximum point to the second local maximum point. The “Standing Period” is the period from the maximum point (small) to the next maximum point (large), and the “Standing Period” is the period from the maximum point (large) to the next maximum point (small). Become.

Specifically, “walking cycle” and “standing phase” (“free leg period”) are extracted by the following steps 1 to 3.
From the acceleration projection component A _V as a function of (Step 1) time, maximum point for continuous detecting (maximum point (small), the maximum point (large)).
(Step 2) A period from one local maximum point to the second local maximum point (for example, a period from the local maximum point (small) to the next local maximum point (small)) is extracted as a “walking cycle”.
(Step 3) In the “walking cycle”, the period in which the maximum point is from (small) to (large) is defined as “standing phase” (the period in which the maximum point is from (large) to (small) is “free leg period”) Extract.

Within such a “walking cycle”, the “stance phase” and the “swing phase” are repeated, so that the posture of the mobile terminal 1 changes without being constant. FIG. 4B shows a graph showing fluctuations in this posture (stationary acceleration unit vector e _GS ). The time axis (time zone) in FIG. 4B coincides with the time axis (time zone) in FIG.

According to FIG. 4 (B), the while varying the acceleration projection component A _V time as shown in FIG. 4 (A), even cosine cosθ of the angle θ of the static state acceleration unit vector e _GS and vertically downward, time Fluctuates with. Here, the cosine cos θ is 1 (θ = 0 °) once in the “stance phase” and once in the “swing phase”. That is, it can be seen that the stationary acceleration unit vector e _GS representing the direction of the stationary acceleration vector A is vertically downward once for each of the “standing phase” and the “free leg period”.

Here, when stationary, the direction of the acceleration vector A is vertically downward. Therefore, this timing is one orientation of the terminal coordinate system was vertically downward in at rest (orientation when stationary acceleration unit vector e _GS) becomes the timing that matches the vertically downward.

In general, since the acceleration vector detected during walking is a combined vector of the gravitational acceleration vector and the motion acceleration vector, the direction of gravity, that is, the vertical downward direction cannot be determined as it is. However, one orientation of the terminal coordinate system was vertically downward in at rest (orientation when stationary acceleration unit vector e _GS) is, at the timing that matches the vertically downward, this orientation (at rest acceleration unit vector e _GS Can be used as “vertically downward”.

The data of the cosine cos θ of the angle θ formed by the stationary acceleration unit vector e _GS with respect to the vertically downward direction shown in FIG. 4B measures the change in the direction of the mobile terminal 1 using, for example, a gyro sensor. It can not be acquired without taking the trouble of etc. On the other hand, the present invention uses the geomagnetic vector M to determine the timing at which the stationary acceleration direction coincides with the vertically downward direction, as will be described next.

According to FIG. 4 (C), the geomagnetic projection component _MGW also changes over time as the posture / orientation of the mobile terminal 1 changes due to walking. The time axis (time zone) in FIG. 4C also coincides with the time axis (time zone) in FIG. The geomagnetic projection component _MGW and the geomagnetic vertical component _MGS are both normalized so that the maximum value is 1. Here, the geomagnetic projection component M _GW coincides with the geomagnetic vertical component M _GS once in the “standing phase” and once in the “swing phase”. The coincidence timing is exactly equal to the above-described timing at which the direction of the stationary acceleration unit vector e _GS coincides with the vertically downward direction.

From this, the geomagnetic projection component _MGW is calculated at each time point, and the calculated geomagnetic projection component _MGW and the determined geomagnetic vertical component _MGS coincide with each other or have a difference within a predetermined range, or By obtaining a time point having a smaller absolute value of the difference among adjacent time points having different signs of the difference between the geomagnetic projection component _MGW and the geomagnetic vertical component _MGS , this time point is determined as a stationary acceleration vector (stationary The time acceleration unit vector e _GS ) can be determined to be a “vertical stationary time point”, which is a time point when the vertical acceleration unit vector e _GS ) is directed downward. Incidentally, when the geomagnetic projection component M _GW geomagnetic vertical component M _GS has a difference within a predetermined range, for example, in the actual measurement value of the geomagnetic projection component M _GW is close to the value of the geomagnetic vertical component M _GS In the case where it fluctuates without reaching, it can be adopted as the time point for determining the “vertical stationary time point”. Furthermore, a time point having a smaller absolute value of the differences among adjacent time points having different signs can be adopted in the case described below.

For example, assuming that the geomagnetic vertical component M _GS = 0.8, the geomagnetic projection component M _GW is 0.70 when t = 0, 0.77 when t = 1, 0.82 when t = 2, If it is observed as 0.85 when t = 3, the time point when the geomagnetic projection component M _GW matches the geomagnetic vertical component M _GS is estimated to be between t = 1 and t = 2. The However, since the observation time points are discrete, the M _GW value at a time point between t = 1 and t = 2 cannot be known. Therefore, the time point of M _GW = 0.82 that is closest to 0.8 (the absolute value of the difference is minimum), that is, t = 2 is set as the “vertical stationary time point”.

  As described above, the “vertical stationary time point” exists once in each of the “standing phase” and “swing phase”. Both of these may be adopted as “vertical stationary time points”, or only one of them may be adopted.

  The stationary acceleration vector measured at the “vertical stationary time” determined as described above can be determined as a “vertically downward” vector (that is, a gravitational acceleration vector). This makes it possible to accurately determine “vertical downward” even in a situation where the posture of the mobile terminal 1 varies while walking.

As described above, in the present invention, the “vertical stationary time point” is determined using the geomagnetic vector M. Since this geomagnetic vector M generally has a stable magnitude and a constant direction with respect to the vertical downward direction within a range that can be reached by normal walking on the ground, and can always be measured, It can be used as a reference for orientation. Therefore, by comparing the geomagnetic projection component M _GW of the geomagnetic vector M with the geomagnetic vertical component M _GS , the stationary acceleration vector (stationary acceleration unit vector e _GS ) (which is vertically downward when stationary) is exactly The “vertical stationary time point”, which is the time point when vertically downward, can be determined more accurately. Therefore, a more accurate “vertically downward” vector (that is, a gravitational acceleration vector) can be acquired even while walking.

Also, as will be described later, and the gravitational acceleration vector G, and the geomagnetic vector M _T in the "vertical stationary point", and a right / left vector U to be described later, to determine the "traveling direction" of the user to walk Can do. At this time, calculating the gravitational acceleration vector G more accurately is crucial for improving the accuracy of the determined “traveling direction”. Here, by using the present invention, it is possible to more accurately determine the “traveling direction” of the walking user by obtaining a more accurate “vertical downward” vector, that is, a gravitational acceleration vector. is there.

Here, as a change mode, the “relative stationary time point” that is the relative position of the determined “vertical stationary time point” within the determined “walking cycle”, “standing phase”, or “swinging phase” It is also possible to calculate. For example, as shown in FIG.
(A) the position of the first (in the "stance") in the walking period T _W of the vertical stationary point, a "relative stationary point" _{p × T W (1 <p} <1),
(B) the position in the walking period T _W of the second (in "swing phase") vertically stationary point, and "relative stationary point" _{q × T W (p <q} <1).

In this case, if the walking cycle T _W and p (or q) are determined, the “relative stationary time point” p × T _W (or q × T _W ) is determined. It is also preferable to determine the “vertical stationary time point” by using the “relative stationary time point” periodically generated as described above. For example,
(A) The calculated geomagnetic projection component M _GW is compared with the determined geomagnetic vertical component M _GS only during a predetermined measurement time including a “relative stationary time” that occurs periodically, and the two coincide with each other Alternatively, a time point having a difference within a predetermined range, or a time point having the smaller absolute value of the differences among adjacent time points having different signs of the difference between the geomagnetic projection component _MGW and the geomagnetic vertical component _MGS is referred to as “vertical stationary”. It may be “time point”.
further,
(B) A “relative stationary time point” that is generated periodically regardless of the geomagnetic projection component M _GW and the geomagnetic vertical component M _GS for a predetermined period after the “relative stationary time point” is calculated. It is also possible to decide on.

  In this way, by using the “relative stationary time point”, it is possible to reduce the amount of calculation rather than directly calculating the “vertical stationary time point” every time, and to determine the vertical downward more quickly, and further reduce the power consumption. Can do.

It is also possible to cope with geomagnetism fluctuations caused by places that pass during walking. That is, if the geomagnetic vector M fluctuates due to the influence of the walking environment during walking, an error may also occur in the “vertical stationary time point” directly calculated from the geomagnetic projection component _MGW and the geomagnetic vertical component _MGS . However, this error can be corrected by using a “relative stationary time point” that periodically occurs and comparing the “vertical stationary time point” with this “relative stationary time point”. Further, when the magnitude of geomagnetism is monitored and the magnitude does not fall within a predetermined range, the “vertical stationary time point” may be periodically determined using the “relative stationary time point”.

[Determining the direction of travel]
FIG. 5 is a vector diagram for explaining a method of determining the traveling direction of the user walking from the determined vertical downward direction (gravity acceleration vector).

First, the geomagnetic vector M _T at the determined “vertical stationary time”, ie,
(9) M _T = (M _Tx , M _Ty , M _Tz )
Is calculated. Furthermore, at the determined “vertical stationary time point”, the vertical downward stationary acceleration vector is expressed as the gravitational acceleration vector G _S , that is,
(10) G _S = (G _Sx , G _Sy , G _Sz )
Calculate as

Hereinafter, the “direction of travel” can be determined using the following two methods.
(A) A “right / left direction vector U” indicating the right or left side of the pedestrian facing in the traveling direction is calculated, the gravitational acceleration vector G _S , the geomagnetic vector M _T, and the calculated “right / left direction vector” From “U”, the traveling direction at “vertical stationary time” is determined.
(B) A “north / south acceleration vector” and an “east / west acceleration vector” are calculated from the gravitational acceleration vector G _S and the geomagnetic vector M _T to determine the traveling direction at the “vertical stationary time point”.
Here, the method (A) uses the method described in JP2012-168004A, and the method (B) uses the method described in JP2011-163861A. It is. First, the method (A) will be described.

[Method (a): Method using right / left-facing vector U]
(First method)
According to FIG. 5A, a gravitational acceleration vector G _S , a geomagnetic vector M _T, and a “right / left direction vector U” are shown. The “right / left direction vector U” is a vector indicating the right or left side of the pedestrian facing in the traveling direction, and is calculated from a plurality of acceleration vectors A in the detected stance phase or swing phase.

Here, first, an acceleration surface generated by the user's walking motion is determined from a plurality of acceleration vectors A in the stance phase or the swing phase. Next, from the normal vector V _LR of the acceleration surface and the gravitational acceleration vector G _S , the forward / rearward front / rear vector V _FG is _expressed by the following equation (11) V _FG = V _LR × G _S (×: cross product (vector) Product, outer product))
Calculate using.

Next, whether the calculated forward / backward vector V _FG is forward or backward is determined based on the acceleration vector B at the end of the swing phase. The pedestrian's foot during the swing phase is carried from back to front. Therefore, the mobile terminal 1 inserted in the pocket of the trousers moves in a pendulum shape with a generally circular arc. As a result, when the mobile terminal 1 is in front, the acceleration vector is detected backward. That is, the direction of the acceleration vector B at the end of the swing leg period can be determined as “after”. The end point of the swing phase is the start point of the stance phase.

Specifically, the inner product of the backward acceleration vector B and the unit vector e _FB = (e _FBx , e _FBy , e _FBz ) of the forward / rearward vector V _FG , that is, the acceleration longitudinal component B _FG = e _FGx × B _x + e _FGy × B _y + e _FGz × B _z
Negative value → forward / backward vector V _FG : forward,
Positive value → forward / backward vector V _FG : backward direction.
Note that it is naturally possible to make the same forward / reverse determination using the acceleration vector F at the end of the stance phase (at the start of the swing phase).

here,
(A) When the forward / backward vector V _FG is forward (forward vector), the normal vector V _LR used to calculate this V _FG is the rightward “right / leftward vector U” (rightward vector),
(B) When the forward / backward vector V _FG is backward (backward vector), the normal vector V _LR used for the calculation of V _FG is the leftward “right / leftward vector U” (leftward vector).

(Second method)
Further, by taking the outer product of the acceleration vector B and the acceleration vector F at the start and end of the stance phase (or swing phase), the right / left direction vector U = B × F (right direction) (or U = F × B (leftward)) can be calculated.

(Third method)
Further, the inner product of the provisional right / left direction vector U ′ calculated by taking the outer product of the acceleration vector B and the acceleration vector F at the start and end of the stance phase (or the swing phase) and the normal vector V _LR By calculating U ′ · V _LR , the direction of the normal vector V _LR is
Inner product U '· V _LR is a negative value → U' is right if V _LR left, 'V if the left _LR right inner product U' U · V _LR is 'V _LR right if is right, U' positive → U is left If so, it can be determined as _VLR leftward. Next, for the direction of the normal vector V _LR determined in this way,
(A) When V _LR is directed to the right, the normal vector V _LR is set to a “right / left vector U” (right vector) directed to the right,
(B) When V _LR is facing left, the normal vector V _LR can be a leftward “right / left facing vector U” (left facing vector).

(Fourth method)
In the xyz axis, the direction of the provisional right / left direction vector U ′ calculated by taking the outer product of the acceleration vector B and the acceleration vector F at the start and end of the stance phase (or the swing phase) is the most. When the acceleration plane is estimated based on the least square method for the near axis, the direction of the right / left direction vector (normal vector) is determined based on the provisional right / left direction vector U ′ and the normal vector V _LR. It is also possible to do. in this case,
(A) When V _LR is directed to the right, the normal vector V _LR is set to a “right / left vector U” (right vector) directed to the right,
(B) When V _LR is facing left, the normal vector V _LR can be a leftward “right / left facing vector U” (left facing vector).

(Determining the direction of travel)
Next, as shown in FIG. 5B, the traveling direction at the “vertical stationary time point” is determined from the gravitational acceleration vector G _S , the geomagnetic vector M _T, and the calculated right / left direction vector U. Specifically, first, an east-facing unit vector e _East or a north-facing unit vector e _North is expressed by the following equation (12) e _East = G _S × M _T / | G _S × M _T |
_{(13) e North = G S} × M T × G S / | G S × M T × G S |
Calculate using. Here, x is a cross product (vector product, outer product).

Next, a rightward unit vector e _Right which is a unit vector of the rightward vector U is calculated, and an angle α formed by the rightward unit vector e _Right and the eastward unit vector e _East is expressed by the following equation (14) α = arccos (( e _East・ e _Right ) / (| e _East || e _Right |))
Calculate using.

Of course, it is also possible to calculate the angle α using the left unit vector e _Left instead of the right unit vector e _Right . It is also possible to calculate an angle α formed by the north unit vector e _North and the right (left) unit vector e _Right (e _Left ). However, it should be noted that in these cases, the finally calculated angle reference is changed.

  Next, an azimuth angle θ indicating a traveling direction is determined using the calculated angle α. Here, the angle α is an inferior angle (0 to 180 degrees). On the other hand, the azimuth angle θ to be obtained is 0 to 360 degrees (clockwise angle with the north azimuth being 0 degrees) and includes a dominant angle. Therefore, it is necessary to convert the angle α into the azimuth angle θ.

  FIG. 6 is a schematic diagram for explaining the relationship between the angle α and the azimuth angle θ.

As shown in FIG. 6A, the directional angle θ of less than 180 degrees coincides with the angle α (θ = α). At this time, the direction of the outer product vector e _East × e _Right of the east unit vector e _East and the right unit vector e _Right coincides with the direction of the gravity acceleration vector G. On the other hand, as shown in FIG. 6B, when the azimuth angle θ is 180 degrees or more, θ = 360 (degrees) −α. At this time, the direction of e _East × e _Right is opposite to the gravitational acceleration vector G.

Accordingly, the direction angle θ with respect to the eastward unit vector e _East can be determined by the following equation, where β is the angle formed by e _East × e _Right and the gravity vector G.
When cos β> 0: θ = α
When cos β ≦ 0: θ = 360 (degrees) −α

[Method (b): Method using acceleration vectors for north / south and east / west]
Next, the above-described method (b) will be described. First, using the above-described equations (12) and (13), the northward unit vector e _North = (e _Nx , e _Ny , e _Nz ) and the east direction unit vector e _East = (e _Ex , e _Ey , e _Ez ) is calculated. Next, the northward acceleration component A _N and the eastward acceleration component A _E of the acceleration vector A = (A _x , A _y , A _z ) are _expressed by the following equation (15) A _N = e _Nx × A _x + e _Ny × A _y + E _Nz × A _{z
(16) A E = e Ex} × A x + e Ey × A y + e Ez × A z
Calculate using.

  Note that the same calculation as described below can be performed by using a south unit vector instead of the north unit vector and a west unit vector instead of the east unit vector. However, it should be noted that in this case, the finally calculated angle reference is changed.

The calculated northward acceleration component A _North and eastward acceleration component A _East are collected, for example, for each step or each walking cycle, and constitute a horizontal acceleration component (acceleration data) group. From this acceleration data group, the azimuth angle θ is determined using the principal component analysis method. This principal component analysis method is a method of calculating one or more principal components having a correlation from a large number of component distributions. The principal component having the largest correlation among them represents an angle indicating the traveling direction of the pedestrian.

(Ｖxx−λ)・(Ｖyy−λ)−Ｖxy・Ｖxy＝０
Ｖxx・Ｖyy−（Ｖxx＋Ｖyy）・λ＋λ²−Ｖxy²＝０
この固有方程式を解くことによって、２つの固有値λが算出される。 Specifically, the i-th data of the two variables x and y (the northward component: x and the eastward component: y) in the horizontal acceleration data are set as x _i and y _i , respectively. At this time, the eigenvalue λ of the n pieces of data is calculated by the following determinant.

(Vxx−λ) · (Vyy−λ) −Vxy · Vxy = 0
Vxx · Vyy− (Vxx + Vyy) · λ + λ ² −Vxy ² = 0
By solving this eigen equation, two eigen values λ are calculated.

Here, Vxx, Vyy, and Vxy are dispersion and covariance of the northward acceleration component A _North and the eastward acceleration component A _East when the northward component is x and the eastward component is y.
Vxx = 1 / n · Σ _{i = 1} ⁿ (x _i -x ^￣ ) ²
_{Vyy = 1 / n · Σ i} = 1 n (y i -y ¯) 2
_{Vxy = 1 / n · Σ i} = 1 n (x i -x ¯) (y i -y ¯)

Of the two eigenvalues calculated lambda, when larger one with lambda _1, eigenvector is calculated by the following equation.

When the calculated eigenvector [e ₁ , e ₂ ] is used, the angle indicating the traveling direction in the horizontal acceleration data group is calculated by the following equation.
(An angle indicating the traveling direction) = Tan ⁻¹ (e ₂ / e ₁ )

  As described above in detail, according to the present invention, even if the pedestrian is wearing the portable terminal in a pants pocket or the like, the vertical direction is related to the progress. The downward direction can be determined more accurately. In addition, by acquiring this accurate vertical downward vector, that is, the gravitational acceleration vector, it is possible to determine the traveling direction of the pedestrian more accurately.

  In the various embodiments of the present invention described above, various changes, modifications and omissions within the scope of the technical idea and the viewpoint of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be any limitation. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Mobile terminal 100 Acceleration sensor 101 Geomagnetic sensor 102 Display part 103 Positioning part 110 Stillness determination part 111 Static acceleration direction determination part 112 Geomagnetic vertical component determination part 113 Geomagnetic projection component calculation part 114 Vertical stationary time determination part 115 Acceleration time change calculation / Accumulation unit 116 Relative still time calculation unit 117 Progression related direction determination unit 118 Right / left vector calculation unit 119 Map information storage unit 120 Display control unit

Claims (11)

An acceleration sensor capable of measuring acceleration as a vector quantity and a geomagnetic sensor capable of measuring geomagnetism as a vector quantity are related to the progress of the user carrying the terminal based on the measured acceleration vector A and geomagnetic vector M A mobile device that determines the orientation,
Stationary determination means for determining whether or not the mobile terminal is stationary;
A stationary acceleration direction determining means for determining a stationary acceleration direction which is a direction of an acceleration vector A when it is determined that the portable terminal is stationary in a terminal coordinate system fixed to the portable terminal. When,
Geomagnetic vertical component determining means for determining a geomagnetic vertical component M _GS is a projection component of the the resting acceleration direction of the geomagnetic vector M in time of the determination of the mobile terminal is stationary has been performed,
A geomagnetism projection component calculating means for calculating a geomagnetism projection component _MGW that is a projection component of the geomagnetic vector M at each time point toward the stationary acceleration direction;
By comparing the calculated geomagnetic projection component _MGW with the determined geomagnetic vertical component _MGS , the vertical stationary time point, which is the time point when the stationary acceleration direction can be determined vertically downward, is determined. A portable terminal comprising: a vertical stationary time point determining means. The vertical stationary time point determination means is a time point at which the calculated geomagnetic projection component M _GW matches the determined geomagnetic vertical component M _GS or when there is a difference within a predetermined range, or the geomagnetic projection component M _GW. The time point having the smaller absolute value of the difference among adjacent time points having different signs of the difference between the magnetic field vertical component _MGS and the geomagnetic vertical component _MGS is determined as a vertical stationary time point. Mobile device. An acceleration time change calculating means for calculating one acceleration component or acceleration magnitude in the acceleration vector A at each time point;
Based on the maximum point or the minimum point in the time change of the acceleration component or the magnitude of the acceleration, the user's walking cycle, the stance phase in which the user's foot is on the ground, or the user's foot is separated from the ground Detects the swing phase, which is the period carried before, and calculates the relative rest time that is the relative position of the determined vertical rest time within the walking cycle, the stance phase, or the swing phase And a relative stationary time point calculating means for
The portable terminal according to claim 1 or 2, wherein the vertical stationary time point determination unit determines the vertical stationary time point using the relative stationary time point that is periodically generated. The vertical stationary time point determination means compares the calculated geomagnetic projection component M _GW with the determined geomagnetic vertical component M _GS only during a predetermined measurement time including the relative stationary time point that occurs periodically. The mobile terminal according to claim 3. The vertical stationary time determination means, the relative stationary time calculating means the relative quiescent time a predetermined period of time from the calculated, regardless of the with the geomagnetic projection component M _GW and the geomagnetic vertical component M _GS, periodically The portable terminal according to claim 3, wherein the relative stationary time point to be generated is determined as a vertical stationary time point. An acceleration time change calculating means for calculating one acceleration component or acceleration magnitude in the acceleration vector A at each time point;
Based on the maximum or minimum point in the time change of the acceleration component or the magnitude of the acceleration, the stance phase in which the user's foot is on the ground, or the user's foot is moved away from the ground The right / left direction vector U indicating the right or left direction of the user facing the traveling direction is calculated from a plurality of acceleration vectors A in the stance phase or the free leg phase. A leftward vector calculating means;
Calculating a gravitational acceleration vector G based on an acceleration vector A when it is determined that the mobile terminal is stationary; the gravitational acceleration vector G; and a geomagnetic vector M at the time of the vertical stationary state; 6. The mobile phone according to claim 1, further comprising: a travel-related direction determining unit that determines a travel direction at the vertical stationary time point from the calculated right / left direction vector U. 6. Terminal. The right / left direction vector calculating means calculates the right / left direction vector U by taking the outer product of the acceleration vectors A at the start and end times of the stance phase or the swing phase period. Mobile devices. The right / left direction vector calculating means determines an acceleration plane generated by a user's walking motion from a plurality of acceleration vectors A in the stance phase or swing phase, and uses the right / left direction vector U as a normal vector of the acceleration plane. The mobile terminal according to claim 6, wherein the mobile terminal is calculated. A gravitational acceleration vector G is calculated based on the acceleration vector A when it is determined that the mobile terminal is stationary, and the gravitational acceleration vector G and the geomagnetic vector M at the time of the vertical stationary time are calculated. Calculating a group of horizontal acceleration components by calculating a north / south acceleration vector that is a north or south vector and an east / west acceleration vector that is an east or west vector ;
Calculating variances Vxx, Vyy and covariance Vxy in the horizontal acceleration component group, and calculating an eigenvalue λ based on the variance and the covariance;
The eigenvector [e ₁ , e ₂ ] is calculated using the eigenvalue λ, and the angle Tan ⁻¹ (e ₁ / e ₂ ) calculated from the eigenvector [e ₁ , e ₂ ] is determined in the traveling direction. The portable terminal according to any one of claims 1 to 5, further comprising a progress-related direction determining unit. An acceleration sensor capable of measuring acceleration as a vector quantity and a geomagnetic sensor capable of measuring geomagnetism as a vector quantity are related to the progress of the user carrying the terminal based on the measured acceleration vector A and geomagnetic vector M A program that allows a computer installed in a mobile terminal to determine the orientation to function.
Stationary determination means for determining whether or not the mobile terminal is stationary;
A stationary acceleration direction determining means for determining a stationary acceleration direction which is a direction of an acceleration vector A when it is determined that the portable terminal is stationary in a terminal coordinate system fixed to the portable terminal. When,
Geomagnetic vertical component determining means for determining a geomagnetic vertical component M _GS is a projection component of the the resting acceleration direction of the geomagnetic vector M in time of the determination of the mobile terminal is stationary has been performed,
A geomagnetism projection component calculating means for calculating a geomagnetism projection component _MGW that is a projection component of the geomagnetic vector M at each time point toward the stationary acceleration direction;
By comparing the calculated geomagnetic projection component _MGW with the determined geomagnetic vertical component _MGS , the vertical stationary time point, which is the time point when the stationary acceleration direction can be determined vertically downward, is determined. A program for a portable terminal, which causes a computer to function as a vertical stationary time determination means. The direction of the acceleration vector A and the geomagnetic vector M measured with respect to the direction of a user carrying a portable terminal equipped with an acceleration sensor capable of measuring acceleration as a vector quantity and a geomagnetic sensor capable of measuring geomagnetism as a vector quantity. A progress-related orientation determination method based on
A first step of determining whether or not the mobile terminal is stationary;
The stationary acceleration direction determining means determines a stationary acceleration direction which is the direction of the acceleration vector A when it is determined that the portable terminal is stationary in the terminal coordinate system fixed to the portable terminal. A second step of determining;
Geomagnetic vertical component determining means, a third to determine the geomagnetic vertical component M _GS is a projection component of the the resting acceleration direction of the geomagnetic vector M in time of the determination of the mobile terminal is stationary were made And the steps
Geomagnetic projection component calculating means, and a fourth step of calculating geomagnetic projection component M _GW is a projection component to the resting acceleration direction of the geomagnetic vector M at each time point,
A point in time when the vertical stationary time determination means can determine the stationary acceleration direction vertically downward by comparing the calculated geomagnetic projection component _MGW with the determined geomagnetic vertical component _MGS. And a fifth step of determining a vertical stationary time point.

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