JP2009133691A - Portable terminal, program, and method for determining traveling direction of pedestrian by using acceleration sensor and geomagnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal, a program, and a method for determining as accurately as possible the traveling direction of a pedestrian by using an acceleration sensor and a geomagnetic sensor mounted on the portable terminal even in the case the pedestrian is walking with the portable terminal in hand. <P>SOLUTION: This portable terminal comprises a traveling direction determination means for determining the traveling direction of the pedestrian. The determination means comprises a plane approximation means for plotting acceleration data and geomagnetic data corresponding to the passage of time on a three-dimensional coordinate system to derive an approximate acceleration plane and a geomagnetic plane, an interplanar angle calculation means for calculating an interplanar angle ψ between the acceleration plane and the geomagnetic plane, and a direction angle calculation means for calculating a direction angle θ relative to the geomagnetic plane as the traveling direction of the pedestrian based on the interplanar angle ψ. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a portable terminal, a program, and a method for determining a traveling direction of a pedestrian using an acceleration sensor and a geomagnetic sensor. In particular, the present invention relates to an autonomous navigation technique for deriving a traveling direction and a current position in real time.

  Conventionally, there is an autonomous navigation technique that derives a traveling direction and a current position in real time using an acceleration sensor and a direction sensor. Autonomous navigation technology is combined with GPS (Global Positioning System) technology and is mainly used for a car navigation system. The car navigation system displays, on a display, an accurate traveling direction and current position, and a travel route guide to a destination for a driver of a car.

  The car navigation system corrects the current position information measured by the GPS by an autonomous navigation technique such as a vehicle speed pulse or a gyro. Further, the road map information is read out as necessary, and the traveling direction and the current position are corrected so that the current travel route coincides with the road (refer to map matching technology based on a projection method, for example, Patent Document 1). As a result, it is possible to prevent the current position from being a position not on the road due to a sensor error.

  On the other hand, there is a system in which such navigation technology is applied to a portable terminal possessed by a pedestrian. Specifically, a cumulative current position from the starting point is derived using the detected “number of steps” of the pedestrian and the “step length” of the pedestrian (see, for example, Patent Document 2). When the autonomous navigation technology is applied to a pedestrian, acceleration components other than horizontal movement are also detected. Thus, the measured distance is derived from the number of steps and the step length, rather than simply integrating the output of the acceleration sensor.

The “number of steps” is detected by taking the acceleration for each axis detected by the acceleration sensor in the mobile terminal as the square root of the sum of squares (√ (x ² + y ² + z ² )) and taking the peak-to-peak as one step (for example, (See Patent Document 3). The “step length” is preset by the user or estimated from the height of the user. Alternatively, according to another technique, there is a technique of calibrating the stride by causing a pedestrian to walk a specified distance (see, for example, Non-Patent Document 1).

  The “traveling direction” is detected by the “direction sensor”. As the direction sensor, a geomagnetic sensor is generally used. There is also a technique for three-dimensionally displaying the orientation and direction of a terminal detected using a geomagnetic sensor on a display (see, for example, Patent Document 4). In addition, when there are a plurality of roads through an intersection in the traveling direction, there is a technique in which the intersection is the current position (see, for example, Patent Document 5).

  A technology to determine the current position using autonomous navigation technology, in order to prevent the influence of the cumulative error of sensor data, when the right turn or left turn at the intersection is detected, the intersection is the starting point for specifying the current position (See, for example, Patent Document 6). That is, every time a turn is detected, the cumulative error of the sensor data is reset, and the previous cumulative error does not affect the subsequent specification of the current position.

JP-A-5-061408 Japanese Patent Laid-Open No. 9-089584 Japanese Patent Laying-Open No. 2005-038018 JP 2004-046006 A JP-A-3-099399 JP 63-011813 A "Nike + iPod User's Guide", page 27, "online", [searched August 31, 2007], Internet <URL: http://manuals.info.apple.com/en/nikeipod_users_guide.pdf>

  According to the technique described in Patent Document 4, an orientation in a stationary state is derived using an acceleration sensor and a geomagnetic sensor. However, when the azimuth is actually derived by a portable terminal held by a pedestrian, the waveform detected by the sensor is disturbed due to the handheld state, and the correct azimuth cannot be derived. In particular, since the pedestrian shakes his / her hand forward and backward, the data detected by the sensor varies greatly. Moreover, it is difficult to use a gyro sensor mounted on a car navigation system for a portable terminal held by a pedestrian due to size and cost constraints.

  Therefore, the present invention uses the acceleration sensor and the geomagnetic sensor mounted on the mobile terminal as accurately as possible even when the pedestrian is walking with the mobile terminal handheld. It is an object of the present invention to provide a portable terminal, a program, and a method that are determined.

According to the present invention, the acceleration sensor that outputs the triaxial acceleration data, the geomagnetic sensor that outputs the triaxial geomagnetic data, and the traveling direction determination means that determines the traveling direction of the pedestrian from the acceleration data and the geomagnetic data. A portable terminal possessed by a pedestrian,
The direction of travel determination means is
A plane approximation means for plotting acceleration data and geomagnetic data according to the passage of time in a three-dimensional coordinate system and approximately deriving an acceleration surface and / or a geomagnetic surface caused by arm swing;
A plane-to-plane angle calculating means for calculating a plane-to-plane angle φ between the acceleration surface and the geomagnetic surface;
And a direction angle calculating means for calculating a direction angle θ with respect to the geomagnetic surface based on the interplane angle φ.

According to another embodiment of the portable terminal of the present invention, the direction angle calculation means uses the angle I formed by the direction of gravity and the geomagnetism,
Angle measure θmeasure = arcsin (tan (φ) / tan (I))
It is also preferable to calculate the direction angle θ = θmeasure when the geomagnetic surface is on the left side of the acceleration surface toward the north, and the direction angle θ = −θmeasure when the geomagnetic surface is on the right side of the acceleration surface.

  According to another embodiment of the portable terminal of the present invention, it is also preferable that the plane approximation means approximates the acceleration surface and / or the geomagnetic surface by a least square method.

According to another embodiment of the mobile terminal of the present invention,
Gait timing determination means for classifying the acceleration data input from the acceleration sensor for each number of steps or for each time unit based on the number of steps, and outputting to the traveling direction determination means;
It is also preferable to further include a direction change determination unit that determines whether or not the direction change has been made for each step number or the traveling direction for each time unit based on the step number output from the traveling direction determination unit.

According to another embodiment of the mobile terminal of the present invention,
It further has a forward determining means for determining the direction of walking of the pedestrian, that is, the front of the acceleration surface,
Preferably, the forward determining means determines the larger one of the continuous peak points of the composite acceleration in the acceleration data string output from the acceleration sensor as the front of the acceleration surface, and notifies the direction change determining means to that effect.

According to another embodiment of the portable terminal of the present invention, about acceleration data and geomagnetic data input to the plane approximation means,
It is also preferable to further include filter means for storing data in a predetermined time range and removing a predetermined ratio of data from the maximum value and the minimum value.

According to another embodiment of the mobile terminal of the present invention, for the direction angle θ output from the direction angle calculation means,
It is also preferable to further include correction means for storing the direction angle θ in a predetermined time range and removing the direction angle θ in which a change before and after the direction angle θ is equal to or greater than a predetermined angle threshold.

According to the present invention, an acceleration sensor that outputs triaxial acceleration data and a geomagnetic sensor that outputs triaxial geomagnetic data, and a computer mounted on a portable terminal carried by a pedestrian, the acceleration data And a program for a mobile terminal that functions as a traveling direction determining means for determining a traveling direction of a pedestrian from geomagnetic data,
The direction of travel determination means is
A plane approximation means for plotting acceleration data and geomagnetic data according to the passage of time in a three-dimensional coordinate system and approximately deriving an acceleration surface and a geomagnetic surface caused by arm swing;
A plane-to-plane angle calculating means for calculating a plane-to-plane angle φ between the acceleration surface and the geomagnetic surface;
The computer is caused to function as direction angle calculation means for calculating the direction angle θ with respect to the geomagnetic surface based on the interplane angle φ.

According to the present invention, a mobile terminal possessed by an pedestrian having an acceleration sensor that outputs triaxial acceleration data and a geomagnetic sensor that outputs triaxial geomagnetic data walks from acceleration data and geomagnetic data. A method of determining the direction of travel of a person,
A first step of plotting acceleration data and geomagnetic data according to the passage of time in a three-dimensional coordinate system and approximately deriving an acceleration surface and a geomagnetic surface caused by arm swing;
A second step of calculating a plane angle φ between the acceleration surface and the geomagnetic surface;
And a third step of calculating a direction angle θ with respect to the geomagnetic surface based on the interplane angle φ.

  According to the mobile terminal, the program, and the method of the present invention, even if the pedestrian is walking with the mobile terminal held by hand, the pedestrian can be detected using the acceleration sensor and the geomagnetic sensor mounted on the mobile terminal. Can be determined as accurately as possible.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram illustrating a walking mode of a pedestrian, an acceleration variation direction, and a geomagnetic variation direction.

  According to FIG. 1, a pedestrian is walking while holding a portable terminal and shaking his / her hand back and forth. If such a general walking mode is seen from the lateral direction, the position of the mobile terminal fluctuates back and forth in a pendulum shape while drawing an arc. Further, when viewed from the traveling direction, the position of the mobile terminal fluctuates up and down.

  The shoulder portion of the arm holding the mobile terminal serves as a rotation axis of an arc drawn by the position change of the mobile terminal. This curve variation is detected by an acceleration sensor or a geomagnetic sensor mounted on the portable terminal. That is, a plane (fan shape) composed of the rotation axis and the arc is represented as an acceleration surface (a surface formed by an acceleration vector group). As long as the mobile terminal is shaken by hand, this acceleration plane is parallel to the traveling direction.

Further, by obtaining the square root of the sum of squares (√ (x ² + y ² + z ² )) from the acceleration data output from the acceleration sensor, a combined acceleration can be obtained. According to FIG. 1, the position A, the position B, and the position C are represented as the position of the mobile terminal held by the pedestrian. The position B is when the hand of the pedestrian is directly below (the lowest point), and the combined acceleration of the handheld portable terminal becomes a maximum (maximum). Conversely, position A and position C are when the pedestrian's hand is at the highest position (top point), and the resultant acceleration is minimal (minimum). Therefore, the position of the mobile terminal when the combined acceleration becomes maximum represents the direction of gravity. Thus, the acceleration plane based on the arm swing direction and the gravity direction can be derived from the acceleration data.

  Furthermore, geomagnetism has arrived for pedestrians and mobile terminals. As long as the pedestrian holds the terminal in a constant posture and travels straight in one direction, the arrival direction in the geomagnetic sensor coordinate system is the same. However, in order for a pedestrian to swing his / her portable terminal back and forth, the direction of arrival of geomagnetism varies in a curved manner according to his arm swing. This curve variation is detected by a geomagnetic sensor mounted on the portable terminal. That is, the surface formed by the axis and the curve is represented as a geomagnetic surface (a surface formed by a geomagnetic vector group).

  FIG. 2 is an explanatory diagram showing an acceleration surface and a geomagnetic surface that actually occur.

  According to FIG. 2, the three-axis acceleration data (x, y, z) obtained from the acceleration sensor and the three-axis geomagnetic data (x, y, z) obtained from the geomagnetic sensor are expressed in three-dimensional coordinates. Plotted in the system. FIG. 2 also shows geomagnetism and acceleration when the mobile terminal is located at position A, position B, and position C shown in FIG. By connecting the geomagnetism and acceleration plots at positions A, B and C, the geomagnetic surface and the acceleration surface can be detected.

  Moreover, according to FIG. 2, the pedestrian is walking in the direction of the direction angle θ with respect to the geomagnetism coming from the south. At this time, the acceleration plane can be detected in parallel to the traveling direction according to the arm swinging motion of the pedestrian holding the mobile terminal, and the geomagnetic plane can be detected on the side opposite to the geomagnetism arrival direction. This geomagnetic surface constitutes a part of a side surface of a cone having a straight line passing through the origin and perpendicular to both the traveling direction and the gravity direction as an axis and having a geomagnetic vector as a generating line.

  FIG. 3 is an explanatory diagram for calculating the angle amount θmeasure according to the present invention.

  According to FIG. 2, the geomagnetic surface is represented by a curved surface corresponding to the arm swing, but according to the present invention, the geomagnetic surface is approximated to a plane as shown in FIG. By approximating the geomagnetic surface to a plane, the plane angle φ between the acceleration surface and the geomagnetic surface can be calculated. The acceleration surface also needs to be approximated and planarized when it becomes a curved surface by arm swing.

As a method of approximating the curved surfaces of the geomagnetic surface and the acceleration surface to a plane, for example, there is a least square method. The least square method is a method of determining each coefficient of the prediction function f (x) for the phenomenon so that the sum of the squares of the residuals is minimized. The residual, and the i-th data _{n i} with respect to the predicted function values f _{(n i),} which is the difference between the measured data _{m i,} i.e. _m i -f _{(n i).}

In general, a plane passing through the origin is represented by the following equation (1).
ax + by + cz = 0 Formula (1)
At this time, (a, b, c) is a normal vector with respect to the plane.

Here, in order to simplify the calculation, Equation (1) is transformed into Equation (2).
z = αx + βy Equation (2)
Since (a, b, c) is a normal vector, there is no problem when c = -1.

When n point groups x _i , y _i , and z _i (i = 1 to n) are given, α and β that minimize the following expression (3) may be calculated.
S = Σ _{i = 1} ⁿ (z _i −αx _i −βy _i ) Equation (3)

Here, it is assumed that it is defined as follows.
A = Σ _{i = 1} ⁿ (x _i ² )
B = Σ _{i = 1} ⁿ (y _i ² )
C = Σ _{i = 1} ⁿ (z _i ² )
D = Σ _{i = 1} ⁿ (x _i × y _i )
E = Σ _{i = 1} ⁿ (x _i × z _i )
F = Σ _{i = 1} ⁿ (y _i × z _i )

At this time, the expression (3) becomes the following expression (4).
S = Aα ² + Bβ ² + C + 2αβD-2αE-2βF Formula (4)

When Expression (4) is regarded as a function of α, it becomes a concave quadratic function, and the minimum value is minimized. The same applies to β. That is, S is partially differentiated with respect to α and β, and a point that becomes 0 is obtained.

When the equations (5) and (6) are solved, they can be calculated as the following equations (7) and (8).
α = (BE-DF) / (AB-D ² ) Formula (7)
β = (AF−DE) / (AB−D ² ) Formula (8)
As described above, the normal vector is (α, β, −1).

According to Table 1 below, the observed acceleration data x, y, and z are represented based on the time lapses p _{1 to} p ₉ .

According to Tables 1 and 2, α and β are calculated as follows.
α = 0.012705529
β = -0.014162858

According to Table 3 below, the observed geomagnetic data x, y, and z are represented based on the time lapses p _{1 to} p ₉ .

According to Tables 3 and 4, α and β are calculated as follows.
α = -0.31856737
β = 0.690214824

As described above, the inter-plane angle φ is calculated for the two planes of the acceleration plane and the geomagnetic plane as described above. First, each normal vector is defined as follows.
Acceleration surface normal vector Na = (αa, βa, −1)
Normal vector Nm = (αm, βm, −1) of the geomagnetic surface
Na · Nm: inner product of two normal vectors (scalar product)
| Na |: Size of normal vector Na of acceleration surface (length of line segment)
| Nm |: Size of normal vector Nm of geomagnetic surface (length of line segment)
| Na || Nm |: product of the sizes of two normal vectors

According to Tables 1 to 4, Na and Nm are as follows.
Na = (0.012705529, -0.014162858, -1)
| Na | = 1.000180992
Nm = (-0.318567368, 0.690214824, -1)
| Nm | = 1.2561376

At this time, the plane-to-plane angle φ can be calculated from the relationship between the angle formed by the vector and the inner product as follows.
Na · Nm = | Na || Nm | cosφ Formula (9)
cosφ = (Na · Nm) / (| Na || Nm |) Equation (10)
φ = arccos ((Na · Nm) / (| Na || Nm |)) Equation (11)

  In addition, according to FIG. 3, the angle I formed by the direction of gravity and the geomagnetic vector is represented. I is determined by the latitude at which the mobile terminal is located.

According to the present invention, first, the angle amount θmeasure with respect to the geomagnetic surface is calculated based on the interplane angle φ. At this time, the angle amount θmeasure is calculated by the following formula using the angle I formed by the gravity direction and the geomagnetism.
Angle measure θmeasure = arcsin (tan (φ) / tan (I))
Thereby, the advancing direction of a pedestrian can be determined.

According to Tables 1 to 4, the inter-plane angle φ is calculated by applying the above formula.
Na · Nm = 0.012705529 × (-0.318567368) + (-0.014162858) × 0.690214824
+ (-1) x (-1)
= 0.986177018
| Na || Nm | = 1.000180992 × 1.2561376
= 1.256365
Na · Nm = | Na || Nm | cosφ Formula (9)
0.986177018 ＝ 1.256365 ・ cosφ
cosφ = (Na · Nm) / (| Na || Nm |) Equation (10)
= 0.986177018 / 1.256365
φ = arccos ((Na · Nm) / (| Na || Nm |)) Equation (11)
= Arccos (0.986177018 / 1.256365)
= 0.668189 [rad]
= 38.28444 [deg]

Finally, the angle amount θmeasure is calculated using the angle I formed by the direction of gravity and the geomagnetism. In the following, the angle I between the direction of gravity and the geomagnetism is 41 °.
θmeasure = arcsin (tan 38.28444 / tan I)
= 65.23026581 [deg]

  FIG. 4 is an explanatory diagram showing a relative positional relationship in the sensor coordinate system between the geomagnetic surface and the acceleration surface when the pedestrian travels in the north direction.

  According to FIG. 4, the gravity direction is set as the downward direction in the figure for simplification, but in which direction gravity is actually detected in the sensor coordinate system depends on the attitude of the terminal. However, the relative positional relationship between the acceleration surface and the geomagnetic surface does not depend on the terminal posture.

  In addition, according to FIG. 4, the acceleration surface moves in a pendulum shape with the axis perpendicular to both the gravity and the traveling direction as a rotation axis by the arm swinging motion, so that the acceleration surface has a plane parallel to the traveling direction. Constitute. The geomagnetic surface is also configured by the same movement as the acceleration surface. At this time, since the geomagnetism is detected in the north-south direction, the geomagnetic surface is parallel (superimposed) to the acceleration surface based on the traveling direction (θ = 0, φ = 0). Therefore, according to the viewpoint a seen from the traveling direction, the back is north, and the geomagnetic surface and the acceleration surface are superimposed and appear as lines. Moreover, according to the viewpoint b seen from the side with respect to the traveling direction, the acceleration surface is seen in front, and the geomagnetic surface superimposed on it is also seen in front. At this time, tanI with respect to the angle I between the gravity direction and the geomagnetism is represented in the horizontal direction. Further, according to the viewpoint c viewed from the direction directly above the vertical, the geomagnetic surface and the acceleration surface are superimposed and appear as lines.

  FIG. 5 is an explanatory diagram showing the relative positional relationship between the geomagnetic surface and the acceleration surface in the sensor coordinate system when the traveling direction of the pedestrian is in the direction of an angle θ with respect to the north.

  According to FIG. 5, unlike the case of heading north, the geomagnetism comes from a direction rotated by θ with respect to the traveling direction with the direction of gravity as the axis. The acceleration surface and the geomagnetic surface are moved in a pendulum-like manner by moving the acceleration vector and the geomagnetic vector about the axis perpendicular to both the gravity and the traveling direction by the arm swinging motion as in the case of moving north. Composed. Therefore, according to the viewpoint a viewed from the traveling direction, the geomagnetic surface with respect to the acceleration surface is at the position of the angle φ. As shown in FIG. 5, tanφ with respect to φ is represented in the horizontal direction. Moreover, according to the viewpoint b seen from the side with respect to the traveling direction, the acceleration surface is seen in front, and the geomagnetic surface superimposed on it is also seen in front. Further, according to the viewpoint c viewed from the direction directly above the vertical, the opposite side of the origin of the geomagnetic surface is located parallel to the traveling direction at a distance of tanφ from the origin.

  FIG. 6 is an explanatory diagram showing the relative positional relationship between the geomagnetic surface and the acceleration surface in the sensor coordinate system when the traveling direction of the pedestrian is toward the west (the direction at an angle of 90 ° with respect to the north). is there.

  According to FIG. 6, the geomagnetism comes from a direction rotated by 90 ° with respect to the traveling direction about the gravity direction. Like the other traveling directions, the acceleration surface and the geomagnetic surface are moved in a pendulum manner by moving the acceleration vector and the geomagnetic vector about the axis perpendicular to both the gravity and the traveling direction by the arm swinging motion. Composed. Therefore, according to the viewpoint a viewed from the traveling direction, the geomagnetic surface with respect to the acceleration surface is at a position of an angle I (= φ) formed by the gravity direction and the geomagnetism. As shown in FIG. 6, tanI with respect to I is represented in the horizontal direction. Moreover, according to the viewpoint b seen from the side with respect to the traveling direction, the acceleration surface is seen in front, and the geomagnetic surface superimposed on it is also seen in front. Furthermore, according to the viewpoint c viewed from the direction directly above the vertical, the opposite side of the origin of the geomagnetic surface is located in parallel with the traveling direction at a distance of tanI from the traveling direction.

  FIG. 7 is an explanatory diagram showing the direction of the direction angle θ. The upper row is a view seen from vertically above with the north at 12 o'clock, and the lower row is a view seen from a direction (viewpoint shown in the upper row) perpendicular to the traveling direction (acceleration plane).

  The angle amount θmeasure mathematically determined by the above-described calculation based on the angle φ between the acceleration surface and the geomagnetic surface and the angle I between the direction of gravity and the geomagnetism is 0 ° to 90 °. On the other hand, the actual direction angle θ is −90 ° to + 90 ° with the clockwise direction from north as the positive direction.

According to FIGS. 7A and 7B, the same angle amount θmeasure is obtained with respect to two positions that are left-right (east-west) symmetrical with respect to the north-south direction. For example, when there are two direction angles of 30 ° (northeast-southwest direction) and −30 ° (northwest-southeast direction), the angle amount θmeasure calculated from φ and I is the same at 30 °. The direction angle θ can be determined by the positional relationship between the acceleration surface and the geomagnetic surface (whether the geomagnetic surface is located on the left or right side of the acceleration surface).
(A) When there is a geomagnetic surface on the left side of the acceleration surface toward north, the direction angle θ = θmeasure.
(B) When there is a geomagnetic surface on the right side of the acceleration surface toward the north, the direction angle θ = −θmeasure.

7C, the traveling direction is the north-south direction, and according to FIG. 7D, the traveling direction is the east-west direction.
(C) When the acceleration surface and the geomagnetic surface are on the same plane and there is no distinction between the right side and the left side, the direction angle θ = θmeasure = 0 °.
(D) Regardless of the position of the geomagnetic surface (right side, left side), the direction angle θ = θmeasure = 90 ° (+ 90 ° and −90 ° are the same as the direction angle).

  The direction angle θ and the angle amount θmeasure are angles formed by the traveling direction with respect to the north-south direction. The traveling direction is an undirected straight line, and there is no distinction between front and rear. At this time, in order to derive a clockwise azimuth angle (0 to 360 °) with north as 0 degree, it is necessary to determine the front (or rear) of the acceleration surface (this determination will be described later). 8 forward determination unit 107).

  The front of the acceleration surface can be specified as the larger one of the continuous peak points of the combined acceleration. Although the magnitude of acceleration generated by walking is symmetric on the left and right sides of the body, the mobile terminal is detected asymmetrically because it is held with one hand (a position biased to the left or right from the center of the body). For example, when a pedestrian is holding a mobile terminal with his right hand, the magnitude of acceleration when kicking the ground with the right foot and the magnitude of acceleration when kicking the ground with the left foot are detected differently. . In this case, the acceleration when kicking the ground with the right foot is larger than the acceleration when kicking the ground with the left foot. Usually, in human walking, a hand and a foot are interlocked. For example, when the right hand is in front, the right foot kicks out the ground. Therefore, if it can be determined that the ground has been kicked with the foot on the side holding the mobile terminal, it can be determined that the mobile terminal at that time is positioned forward.

  FIG. 8 is a functional configuration diagram of the mobile terminal according to the present invention.

  According to FIG. 8, the mobile terminal 1 includes a microprocessor unit 10, a geomagnetic sensor 11, an acceleration sensor 12, a GPS unit 13, a map information storage unit 14, and a display unit 15.

  The geomagnetic sensor 11 measures the direction of geomagnetism in three axial directions (front-rear direction, left-right direction, and up-down direction). The geomagnetic sensor 11 separates the detection coils and outputs values detected from the separated detection coils.

  The acceleration sensor 12 detects acceleration, that is, a change in speed per unit time. In the case of the three-axis type that can detect the tilt of the mobile terminal, three-dimensional acceleration can be detected, and measurement of the gravity (static acceleration) of the earth can be supported.

  The GPS unit 13 measures latitude and longitude information that is the current position of the reference. Using the measured current position as a reference point, the current position of the pedestrian can be integrated according to the number of steps, the step length, and the traveling direction.

  The map information storage unit 14 stores map information representing a travel route such as a road map. The display unit 15 displays the traveling direction and the current position output from the microprocessor unit 10 together with the map information. This provides a navigation function for pedestrians.

  The microprocessor unit 10 includes a walking timing determination unit 101, a traveling direction determination unit 102, a direction change determination unit 103, a stride determination unit 104, a movement amount integration unit 105, a current position determination unit 106, and a front determination unit. A program that functions as 107 is executed.

  The walking timing determination unit 101 divides the acceleration data string output from the acceleration sensor 12 into acceleration data for every predetermined time, for example, for each number of steps, or for each time unit based on the number of steps. For example, the number of steps can be calculated from the change in the combined acceleration, that is, the degree of shaking during movement.

  The traveling direction determination unit 102 determines the traveling direction from the geomagnetic data from the geomagnetic sensor 11 and the acceleration data from the walking timing determination unit 101 at predetermined time intervals. The present invention is based on the method of specifying the traveling direction in the traveling direction determination unit 102.

  The forward determination unit 107 determines the direction of walking of the pedestrian, that is, the front of the acceleration plane, from the acceleration data string output from the acceleration sensor 12. The front of the acceleration surface can be specified by the magnitude of the combined acceleration. For example, when the ground is kicked with the foot on the side holding the mobile terminal, the acceleration increases, and it can be determined that the mobile terminal is positioned forward.

  The direction change determination unit 103 receives data on the traveling direction from the traveling direction determination unit 102 and receives data on the forward direction from the front determination unit 107. The direction change determination unit 103 has a memory and stores data on the direction of travel and the direction as time passes. And the direction change determination part 103 determines whether the direction change was made about the advancing direction of the fixed time range memorize | stored in memory.

  The stride determination unit 104 receives acceleration data for one step from the walking timing determination unit 101, and determines the stride for each step. The determined stride length is output to the movement amount accumulating unit 105. The stride length determination unit 104 also outputs the stride information to the direction change determination unit 103.

  The movement amount accumulating unit 105 receives the traveling direction information from the traveling direction determining unit 102 and the stride information from the stride determining unit 104. Then, the movement amount accumulation unit 105 accumulates the traveling direction and the stride for one step. The current position determination unit 106 acquires map information from the map information storage unit 14 and identifies the current position from the accumulated movement amount. If the current position determination unit 106 determines that the direction change determination unit 103 has changed direction, the current position determination unit 106 determines the position of a nearby intersection in the map information as the current position. If it is determined that the direction has not changed (if it is determined that the vehicle has moved straight), the position projected by map matching is determined as the current position.

  The traveling direction determination unit 102, which is a feature of the present invention, includes a filter unit 1021, a plane approximation unit 1022, an interplane angle calculation unit 1023, a direction angle calculation unit 1024, and a correction unit 1025. The filter unit 1021 and the correction unit 1025 are not essential functions of the present invention, but can improve the accuracy of the traveling direction.

  The plane approximation unit 1022 plots acceleration data and geomagnetic data corresponding to the passage of time in a three-dimensional coordinate system, and generates a coordinate figure as shown in FIG. 2, for example. The input acceleration data and geomagnetic data are a set of a plurality of data detected in a predetermined time unit (for example, one step). Next, the plane approximation unit 1022 approximates the acceleration plane and the geomagnetic plane that do not become a strict plane according to the measurement error of the sensor and the arm swing. The geomagnetic surface is a curved surface unless the pedestrian travels in the north-south direction. Therefore, the curved surface is approximated to a plane by using a known method such as a least square method.

  The plane-to-plane angle calculation unit 1023 calculates the plane-to-plane angle φ between the plane acceleration surface and the plane geomagnetic surface calculated by the plane approximation unit 1022. The interplane angle φ can be calculated from the angle between the normal vectors of both planes. The positional relationship (angle φ) between the acceleration surface and the geomagnetic surface changes depending on the arm swinging direction, that is, the traveling direction of the pedestrian. When the traveling direction is the north-south direction, the acceleration surface and the geomagnetic surface are on the same plane. On the other hand, when the traveling direction is the east-west direction, the angle φ is maximum.

The direction angle calculation unit 1024 calculates an angle amount θmeasure with respect to the geomagnetic surface based on the interplane angle φ calculated by the interplane angle calculation unit 1023. That is, the angle amount θmeasure with respect to the geomagnetic surface is between 0 ° meaning the north-south direction and 90 ° meaning the east-west direction. Here, using the angle I formed by the direction of gravity and the geomagnetism, the angle amount θmeasure is calculated by the following equation.
Angle measure θmeasure = arcsin (tan (φ) / tan (I))

  The direction angle calculation unit 1024 derives the direction angle θ from the positional relationship between the acceleration surface and the geomagnetic surface based on the angle amount θmeasure. When there is a geomagnetic surface on the left side with respect to the acceleration surface, the direction angle θ = θmeasure, and when there is a geomagnetic surface on the right side with respect to the acceleration surface, the direction angle θ = −θmeasure. When the traveling direction is in the north-south direction, the direction angle θ = θmeasure = 0 °, and in the east-west direction, the direction angle θ = θmeasure = 90 ° (+ 90 ° and −90 ° are the direction angles). Are the same).

  The filter unit 1021 stores data in a predetermined time range for acceleration data and geomagnetic data input to the plane approximation unit 1022, and removes a predetermined ratio of data from the maximum value and the minimum value. In other words, unexpected data can be removed.

  The correction unit 1025 stores the direction angle θ in a predetermined time range for the direction angle θ output from the direction angle calculation unit 1024, and the direction angle θ in which a change before and after the direction angle θ is equal to or greater than a predetermined angle threshold value. Remove.

For example, as shown in Table 5 below, when only one data is swung more than a previous value, for example, 20 ° (predetermined angle threshold), the data is removed.

Further, the correction unit 1025 preferably supplements the removed data with the average of the direction angles θ of the unit sections calculated before and after in time as shown in Table 6 below.

Further, the correction unit 1025 preferably averages the accumulated changes in the plurality of direction angles θ. According to Table 7 below, the values are averaged for each direction angle θ within a certain range.

  As described above in detail, according to the mobile terminal, the program and the method of the present invention, even if the pedestrian is walking with the mobile terminal handheld, the acceleration sensor mounted on the mobile terminal And the geomagnetic sensor can be used to determine the traveling direction of the pedestrian as accurately as possible.

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

It is explanatory drawing showing the walk mode of a pedestrian, an acceleration fluctuation direction, and a geomagnetic fluctuation direction. It is explanatory drawing showing the acceleration surface and geomagnetic surface which generate | occur | produce in reality. It is explanatory drawing which calculates angle amount (theta) measure by this invention. It is explanatory drawing showing the relative positional relationship in the sensor coordinate system of the geomagnetic surface and acceleration surface when the advancing direction of a pedestrian is heading to the north. It is explanatory drawing showing the relative positional relationship in the sensor coordinate system of a geomagnetic surface and an acceleration surface in case the advancing direction of a pedestrian is heading to the direction of the angle of (theta) with respect to the north. It is explanatory drawing showing the relative positional relationship in the sensor coordinate system of a geomagnetic surface and an acceleration surface in case the advancing direction of a pedestrian is heading to the west (direction of an angle of 90 degrees with respect to north). It is explanatory drawing showing the direction of direction angle (theta). It is a functional block diagram in the portable terminal of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Portable terminal 10 Microprocessor part 101 Walking timing determination part 102 Travel direction determination part 1021 Filter part 1022 Plane approximation part 1023 Interplane angle calculation part 1024 Direction angle calculation part 1025 Correction part 103 Direction change determination part 104 Step length determination part 105 Movement amount Accumulation unit 106 Current position determination unit 107 Forward determination unit 11 Geomagnetic sensor 12 Acceleration sensor 13 GPS unit 14 Map information storage unit 15 Display unit

Claims (9)

An acceleration sensor that outputs triaxial acceleration data, a geomagnetic sensor that outputs triaxial geomagnetic data, and a traveling direction determination means that determines the traveling direction of the pedestrian from the acceleration data and the geomagnetic data, A portable device carried by a pedestrian,
The traveling direction determination means includes
A plane approximation means for plotting the acceleration data and the geomagnetic data according to the passage of time in a three-dimensional coordinate system and approximately deriving an acceleration plane and / or a geomagnetic plane caused by arm swing;
A plane-to-plane angle calculating means for calculating a plane-to-plane angle φ between the acceleration surface and the geomagnetic surface;
A portable terminal comprising: a direction angle calculating unit that calculates a direction angle θ with respect to the geomagnetic surface based on the interplane angle φ. The direction angle calculation means uses the angle I formed by the direction of gravity and the geomagnetism,
Angle measure θmeasure = arcsin (tan (φ) / tan (I))
To the north, when the geomagnetic surface is on the left side of the acceleration surface, the direction angle θ = θmeasure, and when the geomagnetic surface is on the right side of the acceleration surface, the direction angle θ = −θmeasure is calculated. The mobile terminal according to claim 1.   The mobile terminal according to claim 1, wherein the plane approximation unit approximates the acceleration surface and / or the geomagnetic surface by a least square method. The acceleration data input from the acceleration sensor is divided for each number of steps, or for each time unit based on the number of steps, and the walking timing determining means for outputting to the traveling direction determining means,
The apparatus further comprises direction change determination means for determining whether or not the direction change has been made for each of the number of steps output from the direction of travel determination means or for each time unit based on the number of steps. Item 4. The mobile terminal according to any one of Items 1 to 3. It further has a forward determining means for determining the direction of walking of the pedestrian, that is, the front of the acceleration surface,
The forward determination means determines the larger one of the continuous peak points of the composite acceleration in the acceleration data string output from the acceleration sensor as the front of the acceleration surface, and notifies the direction change determination means to that effect. The mobile terminal according to claim 4. About the acceleration data and the geomagnetic data input to the plane approximation means,
6. The portable terminal according to claim 1, further comprising a filter unit that stores data in a predetermined time range and removes a predetermined ratio of data from a maximum value and a minimum value. For the direction angle θ output from the direction angle calculation means,
7. The apparatus according to claim 1, further comprising correction means for storing a direction angle θ in a predetermined time range and removing the direction angle θ in which a change before and after the direction angle θ is equal to or greater than a predetermined angle threshold. The portable terminal of any one of Claims. A computer having an acceleration sensor that outputs triaxial acceleration data and a geomagnetic sensor that outputs triaxial geomagnetic data, and is mounted on a portable terminal carried by a pedestrian is obtained from the acceleration data and the geomagnetic data. A program for a portable terminal that functions as a traveling direction determining means for determining a traveling direction of the pedestrian,
The traveling direction determination means includes
A plane approximation means for plotting the acceleration data and the geomagnetic data according to the passage of time in a three-dimensional coordinate system, and approximately deriving an acceleration surface and a geomagnetic surface caused by arm swing;
A plane-to-plane angle calculating means for calculating a plane-to-plane angle φ between the acceleration surface and the geomagnetic surface;
A program for a portable terminal, which causes a computer to function as direction angle calculation means for calculating a direction angle θ with respect to the geomagnetic surface based on the interplane angle φ. A portable terminal having an acceleration sensor that outputs triaxial acceleration data and a geomagnetic sensor that outputs triaxial geomagnetic data, and the progress of the pedestrian based on the acceleration data and the geomagnetic data. A traveling direction determination method for determining a direction,
A first step of plotting the acceleration data and the geomagnetic data according to the passage of time in a three-dimensional coordinate system and approximately deriving an acceleration surface and a geomagnetic surface caused by arm swing;
A second step of calculating an interplane angle φ between the acceleration surface and the geomagnetic surface;
And a third step of calculating a direction angle θ with respect to the geomagnetic surface based on the inter-plane angle φ.

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