JP2009229399A - Mobile terminal, program and method for determining pedestrian's traveling direction using acceleration sensor and geomagnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile terminal, program and method for determining a pedestrian's traveling direction as accurately as possible using only a geomagnetic sensor mounted on the mobile terminal even when the pedestrian is walking with the mobile terminal in hand. <P>SOLUTION: A traveling direction determining means of the mobile terminal has: a reference vector deriving means for deriving a gravity vector in a gravity direction from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector; an azimuth datum plane deriving means for deriving a normal vector of an azimuth datum plane comprising the gravity vector and the geomagnetic vector; an acceleration plane computing means for computing the normal vector of an acceleration plane approximately from a plurality of acceleration vectors; and a direction angle computing means for computing an angle defined by the normal vectors of both planes which are the azimuth datum plane and the acceleration plane, as a direction angle. <P>COPYRIGHT: (C)2010,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”, [March 25, 2008 search], Internet <URL: http://manuals.info.apple.com/en/nikeipod_users_guide.pdf>

  According to the technique described in Patent Literature 4, it is possible to derive the azimuth in a stationary state using an acceleration sensor and a geomagnetic sensor. In the stationary state, the acceleration vector detected by the acceleration sensor represents only gravity. Therefore, the direction can be derived from the world coordinate system derived using the gravity vector and the geomagnetic vector.

  However, when the azimuth is derived by a portable terminal carried 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, the acceleration vector generated during walking is a combination of motion acceleration, centrifugal force due to arm swing motion, and the like in addition to gravity. Therefore, since the direction of gravity cannot be determined, the world coordinate system cannot be derived, and eventually the azimuth cannot be derived. 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 reference vector deriving means for deriving a gravity vector in the direction of gravity from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector;
An orientation reference plane deriving means for deriving a normal vector of the orientation reference plane composed of a gravity vector and a geomagnetic vector;
An acceleration surface calculating means for approximately calculating a normal vector of the acceleration surface from a plurality of acceleration vectors;
Direction angle calculating means for calculating an angle formed by a normal vector of the azimuth reference plane and a normal vector of the acceleration plane as a direction angle is provided.

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 mobile terminal of the present invention,
About acceleration data and geomagnetic data input to the reference vector deriving 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 reference vector deriving means for deriving a gravity vector in the direction of gravity from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector;
An orientation reference plane deriving means for deriving a normal vector of the orientation reference plane composed of a gravity vector and a geomagnetic vector;
An acceleration surface calculating means for approximately calculating a normal vector of the acceleration surface from a plurality of acceleration vectors;
The computer is made to function as a direction angle calculation means for calculating an angle formed by normal vectors of both the azimuth reference plane and the acceleration plane as a direction angle.

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,
Deriving a gravity vector in the direction of gravity from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector;
A second step of deriving a gravity vector and a normal vector of the geomagnetic vector corresponding to the gravity vector;
A third step of approximately calculating a normal vector of an acceleration surface from a plurality of acceleration vectors;
And a fourth step of calculating an angle formed by a normal vector between the azimuth reference plane and the acceleration plane as a direction angle.

  According to the portable terminal, the program and the method of the present invention, since the direction angle between the locus of the acceleration data group and the north direction can be calculated, even if the pedestrian is walking with the portable terminal handheld, Using the acceleration sensor and the geomagnetic sensor mounted on the portable terminal, the traveling direction of the pedestrian 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.

  FIG. 2 is a diagram illustrating an acceleration plane and an azimuth reference plane that are actually generated. For the sake of simplicity, the gravity direction is set as the downward direction in the figure, but gravity itself cannot be detected. In addition, in which direction the geomagnetism is actually detected with respect to the sensor coordinate system depends on the attitude of the terminal. However, the relationship between the acceleration plane and the orientation reference plane does not depend on the attitude of the terminal.

  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. An acceleration plane can be detected from a plot of acceleration data measured at different terminal positions. Further, the azimuth reference plane can be detected from a set of acceleration vector and geomagnetic vector at a certain timing.

  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 with the traveling direction and the azimuth reference plane can be detected in parallel with the north-south direction according to the arm swinging motion of the pedestrian holding the mobile terminal.

  According to the present invention, the direction angle θ can be calculated by approximating a plurality of acceleration data to a plane.

As a method for approximately calculating the acceleration surface, 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 ² (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 the following Table 1, the observed acceleration data x, y, z are represented based on the time passages p1 to p9.

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

Normal vector n _a = (α _a , β _a , −1) of the acceleration surface

The azimuth reference plane is a plane whose normal vector is the outer product of the acceleration vector and the geomagnetic vector. In general, the outer product of two vectors a = (x _a , y _a , z _a ), b = (x _b , y _b , z _b ) is obtained by the following equation.
_{a × b = (y a z} b -y b z a, z a x b -z b x a, x a y b -x b y a) (9)
Therefore,
When the acceleration vector a ₀ = (x _a , y _a , z _a ) and the geomagnetic vector m ₀ = (x _m , y _m , z _m ), the normal vector n ₀ = (x _n , y of the azimuth reference plane) _n , z _n ) is
n ₀ = a ₀ × m _{0
= (Y a z m -y m} z a, z a x m -z m x a, x a y m -x m y a) formula (10)
It is represented by

According to Table 3, the normal vector of the azimuth reference plane is calculated as follows.
n ₀ = (− 7977, −31222, −158899)

In order to calculate the direction angle θ, the normal vector is calculated for each of the two planes of the acceleration plane and the orientation reference plane as described above. First, each normal vector is defined as follows.
Normal vector n _a = (α _a , β _a , −1) of the acceleration surface
Normal vector of azimuth reference plane n ₀ = (x _n , y _n , z _n )
n _a · n ₀ : inner product (scalar product) of two normal vectors
| _N a |: the magnitude of the normal vector _{n a} of the acceleration surface (length of the segment)
| N ₀ |: Size of normal vector n ₀ of the orientation reference plane (length of line segment)
| N _a || n ₀ |: product of magnitudes of two normal vectors

According to Tables 1 to 3, _{n a} and _{n 0} is as follows.
n _a = (0.012705529, −0.014162858, −1)
| N _a | = 1.000180992
n ₀ = (− 7977, −31222, −158899)
| N ₀ | = 162133.7041

At this time, the direction angle θ can be calculated from the relationship between the angle formed by the vector and the inner product as follows.
n _a · n ₀ = | n _a || n ₀ | cos θ Equation (11)
cos θ = (n _a · n ₀ ) / (| n _a || n ₀ |) Equation (12)
θ = arccos ((n _a · n ₀ ) / (| n _a || n ₀ |)) Equation (13)

According to Tables 1 to 3, the direction angle θ is calculated by applying the above formula.
n _a · n ₀ = 0.012705529 × (−7977) + (− 0.014162858) × (−31222)
+ (-1) × (-1)
= 159239.8407
| N _a || n ₀ | = 1.000180992 × 162133.7041
= 162163.0490033724672
n _a · n ₀ = | n _a || n ₀ | cos θ Equation (11)
159239.8407 = 162163.0490033724672 ・ cosθ
cos θ = (n _a · n ₀ ) / (| n _a || n ₀ |) Equation (12)
= 159239.8407 / 162163.0490033724672
= 0.981973647
θ = arccos ((n _a · n ₀ ) / (| n _a || n ₀ |)) Equation (13)
= Arccos (0.981973647)
= 0.190161893 [rad]
= 10.89547387 [deg]

  FIG. 3 is an explanatory diagram showing the direction of the direction angle θ. It is the figure which looked at the north from 12 o'clock direction from right above.

  The direction angle θ mathematically determined from the normal vectors of the acceleration plane and the azimuth reference plane by the calculation described above is 0 ° to 180 °. On the other hand, the actual azimuth angle θ is 0 ° to 360 ° with the clockwise direction from north as the positive direction.

  The direction angle θ is an angle 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. According to FIGS. 3A and 3B, the same direction angle θ can be obtained for two positions that are left-right (east-west) symmetrical with respect to the north-south direction. For example, when there are two azimuth angles of 30 ° (northeast direction) and 330 ° (northwest direction), the directional angle θ calculated from the acceleration plane and the azimuth reference plane is the same at 30 °. 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). 4 forward decision 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. 4 is a functional configuration diagram of the portable terminal according to the present invention.

  According to FIG. 4, 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 Hall elements and outputs values detected from the separated Hall elements.

  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, the acceleration data from the acceleration sensor 12, and the walking timing data from the walking timing determination unit 101 every predetermined time. 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 reference vector derivation unit 1022, an orientation reference plane calculation unit 1023, an acceleration plane calculation unit 1024, a direction angle calculation unit 1025, and a correction unit 1026. And have. The filter unit 1021 and the correction unit 1026 are not essential functions of the present invention, but can improve the accuracy of the traveling direction.

  The reference vector deriving unit 1022 derives a gravity vector in the gravity direction from a plurality of acceleration data, and selects a geomagnetic vector corresponding to the gravity vector.

  The azimuth reference plane calculation unit 1023 calculates an azimuth reference plane composed of a set of acceleration vector and geomagnetic vector obtained by the reference vector deriving unit 1022. The orientation reference plane is obtained from the outer product of a set of acceleration vector and geomagnetic vector.

  The acceleration surface calculation unit 1024 approximates a plurality of acceleration vector groups in the unit section to a plane using a known method such as a least square method.

  The direction angle calculation unit 1025 calculates the direction angle θ from the angle between the normal vectors of both planes of the azimuth reference plane calculated by the azimuth reference plane calculation unit 1023 and the acceleration plane calculated by the acceleration plane calculation unit 1024. . The positional relationship between the acceleration plane and the azimuth reference plane varies depending on the arm swinging direction, that is, the traveling direction of the pedestrian.

  The filter unit 1021 stores data in a predetermined time range for acceleration data and geomagnetic data input to the reference vector deriving 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 1026 stores the direction angle θ in a predetermined time range for the direction angle θ output from the direction angle calculation unit 1025, 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 4 below, if only one data is swung more than a previous value, for example, 90 ° (predetermined angle threshold), the data is removed.

Further, the correction unit 1026 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 5 below.

Further, the correction unit 1026 preferably averages the accumulated changes in the plurality of direction angles θ. According to Table 6 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 a figure showing the acceleration surface and azimuth | direction reference plane which generate | occur | produce in reality. 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 Reference vector derivation part 1023 Coordinate system conversion matrix calculation part 1024 Coordinate system conversion part 1025 Direction angle calculation part 1025 Correction part 103 Direction change determination part 104 Step Determining Unit 105 Travel Amount Accumulating Unit 106 Current Position Determining Unit 107 Forward Determining Unit 11 Geomagnetic Sensor 12 Acceleration Sensor 13 GPS Unit 14 Map Information Storage Unit 15 Display Unit

Claims (7)

An acceleration sensor that outputs triaxial acceleration data; a geomagnetic sensor that outputs triaxial geomagnetic data; and a traveling direction determination means that determines a traveling direction of a pedestrian from the acceleration data and the geomagnetic data. A portable terminal owned by a person,
The traveling direction determination means includes
A reference vector deriving means for deriving a gravity vector in the direction of gravity from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector;
An azimuth reference plane deriving means for deriving a normal vector of the azimuth reference plane composed of the gravity vector and the geomagnetic vector;
An acceleration surface calculating means for approximately calculating a normal vector of the acceleration surface from a plurality of acceleration vectors;
A portable terminal, comprising: a direction angle calculating unit that calculates an angle formed by a normal vector of the azimuth reference plane and a normal vector of the acceleration plane as a direction angle. 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 2. The mobile terminal according to Item 1. 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 resultant 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 2. About the acceleration data and the geomagnetic data input to the reference vector deriving means,
The mobile terminal according to any one of claims 1 to 3, further comprising filter means for storing data in a predetermined time range and removing 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,
5. The apparatus according to claim 1, further comprising a correcting unit that stores the direction angle θ in a predetermined time range and removes 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 reference vector deriving means for deriving a gravity vector in the direction of gravity from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector;
An azimuth reference plane deriving means for deriving a normal vector of the azimuth reference plane composed of the gravity vector and the geomagnetic vector;
An acceleration surface calculating means for approximately calculating a normal vector of the acceleration surface from a plurality of acceleration vectors;
A program for a portable terminal, which causes a computer to function as direction angle calculation means for calculating an angle formed by normal vectors of both planes of the azimuth reference plane and the acceleration plane as a direction angle. 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,
Deriving a gravity vector in the direction of gravity from a plurality of acceleration vectors and selecting a geomagnetic vector corresponding to the gravity vector;
A second step of deriving a normal vector of the gravity vector and a geomagnetic vector corresponding to the gravity vector;
A third step of approximately calculating a normal vector of an acceleration surface from a plurality of acceleration vectors;
A method of determining a traveling direction of a mobile terminal, comprising: a fourth step of calculating an angle formed by a normal vector of the azimuth reference plane and the acceleration plane as a direction angle.

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