JP5294983B2 - Portable terminal, program and method for determining direction of travel of pedestrian using acceleration sensor and geomagnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal or the like for determining accurately a traveling direction of a pedestrian by using an acceleration sensor and a geomagnetic sensor in the portable terminal, when the pedestrian is walking with the portable terminal in hand. <P>SOLUTION: This portable terminal includes: a walking reference vector calculation means for calculating a walking reference vector which is a normal vector to an acceleration surface based on arm swing; an azimuth reference vector calculation means for deriving a gravity vector and a geomagnetic vector corresponding thereto, and calculating an azimuth reference vector which is a normal vector to an azimuth reference surface of both vectors; and an azimuth angle calculation means for calculating an azimuth angle in the traveling direction based on both vectors. The walking reference vector calculation means measures a time interval between each minimal point in a change of a synthetic acceleration following elapse of time, and compares two adjacent time intervals. A minimal point at the end point time of a long time interval shows an acceleration surface front (traveling direction front), and a minimal point at the end point time of a short time interval shows an acceleration surface rear (traveling direction rear). <P>COPYRIGHT: (C)2011,JPO&amp;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. There is also a pedestrian route guidance device that uses autonomous navigation technology, and there is a technology that can implement highly accurate route guidance for pedestrians (see, for example, Patent Document 8). According to this technology, there is a geomagnetic sensor and an acceleration sensor, and the relative path based on the detected walking advance direction using the vertical acceleration generated in the vertical direction and the forward acceleration generated in the forward direction. Calculate the direction.

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 JP 2008-107102 A JP 2008-039619 A “Nike + iPod User's Guide”, page 27, “online”, [Search April 26, 2009], Internet <URL: http://manuals.info.apple.com/en/nikeipod_users_guide.pdf> Daisuke Uesaka, Kengo Iwamoto, Shigeki Muramatsu, Satoshi Nishiyama, "Position acquisition system using acceleration and geomagnetic sensors in mobile phones", Proceedings of Multimedia, Distributed, Cooperation and Mobile Symposium, pp.761-767, July 2008

  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.

  According to the technique described in Non-Patent Document 2, when a pedestrian holds a terminal with a built-in acceleration sensor and walks while swinging his / her arm, the pedestrian detects an acceleration surface generated by arm swing motion. The direction of the detected acceleration surface can be regarded as the traveling direction. Here, in order to determine whether the acceleration surface is ahead (forward in the traveling direction) or behind the acceleration surface (backward in the traveling direction), the difference in the size of the minimum point of the combined acceleration is used.

  However, there are actually large individual differences in arm swinging movements when a person walks. For this reason, it is difficult to accurately determine the front or rear of the acceleration surface only from the difference in the resultant acceleration at the minimum point. If the determination on the front or rear of the acceleration plane fails, the finally estimated orientation is the exact opposite of the correct orientation (180 degree inversion). For this reason, the estimation accuracy of the traveling direction may be significantly deteriorated.

  Therefore, the present invention uses the acceleration sensor and the geomagnetic sensor mounted on the mobile terminal even when the pedestrian is walking with the mobile terminal handheld, and the pedestrian travel direction (front direction of travel). ) Is determined as accurately as possible.

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 walking reference vector calculating means for calculating a walking reference vector that is a normal vector with respect to the acceleration surface based on the arm swinging motion;
An azimuth reference vector calculating means for deriving a gravity vector and a geomagnetic vector corresponding to the gravity vector from the acceleration data and the geomagnetic data, and calculating an azimuth reference vector that is a normal vector with respect to the azimuth reference plane of the gravity vector and the geomagnetic vector When,
Azimuth angle calculating means for calculating the azimuth angle of the traveling direction based on the walking reference vector and the azimuth reference vector;
The walking reference vector calculation means measures the time interval between the local minimum points in the change of the composite acceleration with time, compares two adjacent time intervals, and determines the local minimum at the end point of the long time interval. The point represents the front of the acceleration surface (forward in the traveling direction), and the minimum point at the end of the short time interval represents the rear of the acceleration surface (rear in the traveling direction).

According to another embodiment of the mobile terminal of the present invention,
The walking reference vector calculation means converts the walking reference vector R into an outer product (R = B × F (or the acceleration vector B at the minimum point indicating the back of the acceleration surface) and the acceleration vector F at the minimum point indicating the front of the acceleration surface. F × B)),
The azimuth reference vector calculation means calculates the azimuth reference vector E by an outer product (E = G × M (or M × G)) of the gravity vector G and the geomagnetic vector M,
The azimuth calculation means calculates an angle α formed by both vectors from the inner product and the norm (vector magnitude) product using the azimuth reference vector E and the walking reference vector R, and from the angle α formed by the following formula: Deriving the azimuth angle α = arccos ((E ・ R) / (| E || R |))
It is also preferable.

According to another embodiment of the mobile terminal of the present invention,
The azimuth angle calculating means calculates the outer product vector (E × R) of the azimuth reference vector E and the walking reference vector R, and calculates the azimuth angle θ from the angle α formed by the angle β formed by the outer product vector and the gravity vector G by the following equation. Derived cos β ≧ 0: θ = α
cos β <0: θ = 360−α
It is also preferable.

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 portable terminal of the present invention, the acceleration data and the geomagnetic data input to the reference vector deriving means are memorized in a predetermined time range, and a predetermined ratio of data is removed from the maximum value and the minimum value. It is also preferable to further have a filter means.

  According to another embodiment of the portable terminal of the present invention, the direction angle θ output from the direction angle calculation means is memorized for the direction angle θ in a predetermined time range, and the change before and after the direction angle θ is a predetermined angle threshold value. It is also preferable to further have a correction means for removing the directional angle θ as described above.

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 walking reference vector calculating means for calculating a walking reference vector that is a normal vector with respect to the acceleration surface based on the arm swinging motion;
An azimuth reference vector calculating means for deriving a gravity vector and a geomagnetic vector corresponding to the gravity vector from the acceleration data and the geomagnetic data, and calculating an azimuth reference vector that is a normal vector with respect to the azimuth reference plane of the gravity vector and the geomagnetic vector When,
Azimuth angle calculating means for calculating the azimuth angle of the traveling direction based on the walking reference vector and the azimuth reference vector;
The walking reference vector calculation means measures the time interval between the local minimum points in the change of the composite acceleration with time, compares two adjacent time intervals, and determines the local minimum at the end point of the long time interval. The point represents the front of the acceleration surface (front in the traveling direction), and the computer functions so that the minimum point at the end of the short time interval represents the rear of the acceleration surface (rear in the traveling direction).

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 calculating a walking reference vector that is a normal vector for an acceleration surface based on an arm swinging motion;
A second step of deriving a gravity vector and a geomagnetic vector corresponding to the gravity vector from the acceleration data and the geomagnetic data, and calculating an orientation reference vector that is a normal vector with respect to the orientation reference plane of the gravity vector and the geomagnetic vector; ,
A third step of calculating an azimuth angle of the traveling direction based on the walking reference vector and the azimuth reference vector;
The first step is to measure the time interval between the local minimum points in the change in the resultant acceleration with time, compare two adjacent time intervals, and determine the local minimum point at the end of the long time interval. Represents the front of the acceleration surface (front of the traveling direction), and the minimum point at the end of the short time interval represents the rear of the acceleration surface (rear of the traveling direction).

  According to the portable terminal, the program, and the method of the present invention, the azimuth angle between the arm swing direction and the north direction can be calculated. Therefore, even if the pedestrian is walking with the portable terminal in hand, the portable terminal The traveling direction of the pedestrian can be determined as accurately as possible using the acceleration sensor and the geomagnetic sensor mounted on the vehicle.

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 relationship between an arm swing exercise | movement and an acceleration vector. It is explanatory drawing showing the walk reference | standard vector and direction reference | standard vector which generate | occur | produce in reality. It is explanatory drawing which looked at FIG.3 (b) from the perpendicular | vertical upper direction. It is a graph showing the synthetic acceleration according to time passage. It is explanatory drawing showing the relationship between the angle | corner made and an azimuth. It is a functional block diagram in the portable terminal of this invention.

  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 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. Among the front and back of the acceleration surface based on arm swing, the front of the acceleration surface represents the front in the traveling direction (back of the arm), and the rear of the acceleration surface represents the rear in the traveling direction (front of the arm). Accordingly, by determining the front or rear of the acceleration surface, a vector indicating the right (or left) with respect to the traveling direction of the pedestrian can be derived as the “walking reference vector”.

Further, by deriving 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, position a, position i, and position c are shown as the positions of the mobile terminal held by the pedestrian. The position B is when the hand of the pedestrian is directly below, 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, and the resultant acceleration is minimal (minimum). Therefore, the position of the mobile terminal at the maximum point represents the direction of gravity. The two minimum points represent the fan-shaped ends at the front of the acceleration surface (front in the traveling direction) and the rear of the acceleration surface (back in the traveling direction). According to the present invention, forward or backward in the traveling direction can be determined from a difference in time interval required for transition between two local minimum points (front → back and back → front). Thereby, the walking direction 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 an explanatory diagram showing the relationship between the arm swing motion and the acceleration vector.

  According to FIG. 2, the position “a” is the rear in the traveling direction and the position “c” is the front in the traveling direction for the two swing end points of the acceleration surface. The local minimum points represent the fan-shaped ends (position A and position c) of the acceleration surface, with one end being forward in the traveling direction (position u) and the other end being backward in the traveling direction (position a). Thereby, the walking direction can be derived based on the acceleration data.

  FIG. 3 is an explanatory diagram showing walking reference vectors and azimuth reference vectors that actually occur.

  According to FIG. 3A, the triaxial acceleration data (x, y, z) obtained from the acceleration sensor and the triaxial geomagnetic data (x, y, z) obtained from the geomagnetic sensor are Plotted in a three-dimensional coordinate system.

  On the other hand, according to FIG.3 (b), an acceleration surface is detected from the plot of the acceleration data measured in the different terminal position. A vector indicating the right side (or left side) with respect to the acceleration plane (the pedestrian's traveling direction) is referred to as a “walking reference vector”. Moreover, according to FIG.3 (b), the pedestrian is walking in the direction of azimuth angle (theta) with respect to the geomagnetism which has arrived from the south. At this time, the azimuth reference plane can be detected from the acceleration vector indicating the gravity direction and the geomagnetic vector indicating the north direction. A vector indicating east (or west) is defined as an “azimuth reference vector”. According to FIG. 3B, the “walking reference vector” can be detected to the right of the traveling direction and the “azimuth reference vector” can be detected in the east direction according to the arm swinging motion of the pedestrian holding the mobile terminal. According to the present invention, the azimuth angle θ can be calculated based on the walking reference vector and the direction reference vector.

  FIG. 4 is an explanatory view of FIG. 3B viewed from the vertically upward direction.

  According to FIG. 4, the azimuth reference plane is located with north as the upper side. The azimuth reference vector faces east with respect to the azimuth reference plane. Further, the acceleration surface (traveling direction) is located by being inclined clockwise by the azimuth angle θ from the azimuth reference plane. The walking reference vector points to the right with respect to the acceleration plane.

  FIG. 5 is a graph showing the combined acceleration over time.

  According to FIG. 5, the minimum point of the composite acceleration appears both in front and behind the arm with respect to the traveling direction. The time interval between the two minimum points is different between forward → backward (swing down) and backward → forward (swing up). Specifically, the time interval between the minimum points when the arm is raised (backward → front) is longer than the time interval between the minimum points when the arm is swinged down (front → back). When the arm is swung up, the arm is moving from the back in the direction of travel to the front, and when the arm is swung down, the arm is moving from the front in the direction of travel to the back It is.

  As described above, since the acceleration vector moves to the side opposite to the swing of the arm, the front or back of the acceleration surface is reversed with respect to the front or back of the arm. That is, when the arm is ahead in the direction of travel (front of the arm), the acceleration vector is behind in the direction of travel. Conversely, when the arm is behind the direction of travel (back of the arm), the acceleration vector is forward of the direction of travel. Accordingly, with respect to the time interval between the minimum points, the longer time interval is when the arm is raised, and the movement is from the front of the acceleration surface to the rear of the acceleration surface. Conversely, the shorter time interval is the movement from the back of the acceleration surface to the front of the acceleration surface. In addition, if the time interval from the immediately preceding minimum point is longer than the previous time interval, the minimum point represents the forward direction (acceleration plane front). Conversely, if the time interval from the immediately preceding minimum point is shorter than the previous time interval, the minimum point represents the rearward direction of travel (acceleration plane rear).

Table 1 below shows observation data in a predetermined period of acceleration data and geomagnetic data. According to Table 1, the observed triaxial acceleration data a _x , a _y , a _z , the triaxial geomagnetic data m _x , m _y , m _z , the resultant acceleration, and its increase / decrease (+ increases, -Indicates a decrease). Furthermore, a minimum point (1 indicates a minimum point and 0 indicates a non-minimum point), a time interval dt between the minimum points, an increase / decrease thereof, and a determination result in front of or behind the acceleration surface are shown.

  First, a walking reference vector is calculated from the acceleration surface. The walking reference vector indicates the walking direction and is expressed by a normal vector of the acceleration surface. A normal vector extending from the origin can be drawn in two directions with respect to the acceleration plane. Since the acceleration plane indicates the traveling direction (before and after the pedestrian), the normal vectors in the two directions correspond to the right and left sides of the pedestrian. Here, the walking reference vector is defined to be the right side of the pedestrian among the two normal vectors (of course, the left side may be used). The right side is calculated by calculating the outer product of acceleration vectors at two local minimum points indicating the front and rear of the acceleration surface.

The walking reference vector is calculated by the following equation (1).
Acceleration vector at the minimum point indicating the front of the acceleration plane: F = (x _F , y _F , z _F )
Acceleration vector at the minimum point indicating the back of the acceleration plane: B = (x _B , y _B , z _B )
Walking reference vector indicating the right side of the acceleration plane: R = (x _R , y _R , z _R )
R = B × F
_{= (Y B z F -z B} y F, z B x F -x B z F, x B y F -y B x F) Formula (1)

As an example, when the acceleration vectors at time 15070 and time 15530 (thick line) in Table 1 are selected as F and B, respectively, and Expression (1) is applied, the following results.
R = (20300, 114660, −749115)

  Next, an azimuth reference vector is calculated. The azimuth reference vector can be represented by a normal vector with respect to a plane composed of a gravity vector and a corresponding geomagnetic vector. Here, the normal vector can be drawn in two directions from the origin in the same manner as the walking reference vector, but it is necessary to determine it in accordance with the direction determined by the walking reference vector. That is, when the walking reference vector is determined to be right of the pedestrian, it is determined to be right (east), and when it is determined to be left, it is determined to be left (west).

  The acceleration vector at the maximum point of the combined acceleration can be regarded as a gravity vector. Alternatively, the midpoint (average) of acceleration vectors at the two minimum points calculated when determining the walking reference vector may be used (gravity vector G = (B + F) / 2). The geomagnetic vector may be selected at the maximum point as in the case of the gravity vector, or an average of a plurality of geomagnetic vectors detected between the timings of the two minimum points may be used.

An orientation reference vector is derived from the geomagnetic vector corresponding to the gravity vector. Here, the azimuth reference vector is defined as the right side (east) in accordance with the walking reference vector.
An azimuth reference vector is calculated by the following equation (2).
Gravity _{vector: G = (x G, y} G, z G)
Geomagnetic vector: M = (x _M , y _M , z _M )
Walking reference vector: E = (x _E , y _E , z _E )
E = G × M
_{= (Y G z M -z G} y M, z G x M -x G z M, x G y M -y G x M) (2)

As an example, the gravity vector G is set as the midpoint between the acceleration backward vector B and the acceleration forward vector F using the data in Table 1. The geomagnetic vector M is the average of the geomagnetic vectors between B and F. Then, when the formula (2) is applied, the following values are obtained.
Gravity vector: G = (40.5, 907.5, 140)
Geomagnetic vector: M = (534.7, 351, 126. 7)
Orientation reference vector: E = (65810, 69723.3, −470994.5)

The azimuth angle θ is obtained from the angle formed by the walking reference vector and the azimuth reference vector. The angle between the two vectors can be derived from the inner product and the norm (vector magnitude) product. From the azimuth reference vector E and the walking reference vector R, the angle α formed by both vectors is expressed by the following equation.
α = arccos ((E · R) / (| E || R |)) Equation (3)

  Here, the formed 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, the angle formed is converted to an azimuth angle.

  FIG. 6 is an explanatory diagram showing the relationship between the angle formed and the azimuth angle.

  According to FIG. 6, the outer product vector E × R of the azimuth reference vector E and the walking reference vector R indicates the same direction as the gravity vector when θ is less than 180. At this time, θ = α. On the other hand, when θ should be 180 degrees or more, E × R indicates the direction opposite to the gravity vector. At this time, θ = 360−α. Therefore, an angle formed by E × R and the gravity vector G is obtained (cosine instead of angle), and α is converted to θ based on the result.

If the angle formed by E × R and the gravity vector G is β, the following equation is obtained.
cos β ≧ 0: θ = α
cos β <0: θ = 360−α

As an example, when the formula (3) is calculated using the data of Table 1, the following is obtained.
α = 6.3 (deg)

At this time, the outer product vector is as follows.
E × R = (1773434520, 39738069800, −6130390933)
cos β = 1
As a result, the azimuth angle θ is calculated as follows.
θ = α = 6.3 (deg)

  FIG. 7 is a functional configuration diagram of the mobile terminal according to the present invention.

  According to FIG. 7, 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 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 functions as 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, and a current position determination unit 106. Run the program.

  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 direction change determination unit 103 receives the traveling direction data from the traveling direction determination unit 102. The direction change determination unit 103 has a memory and stores data in the traveling direction as time elapses. 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 walking reference vector calculation unit 1022, an azimuth reference vector calculation unit 1023, an azimuth 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 walking reference vector calculation unit 1022 selects the minimum point of synthetic acceleration (highly likely to be the highest point of the arm) from the acceleration data group. The front or rear of the acceleration surface (forward or backward in the traveling direction) is determined from the difference in time interval between the two minimum points. Based on this, a walking reference vector indicating the right side or the left side of the pedestrian traveling direction is calculated.

  The azimuth reference vector calculation unit 1023 obtains a gravity vector and a corresponding geomagnetic vector, calculates a normal vector of a plane composed of the gravity vector, and sets it as an azimuth reference vector. The gravity vector includes acceleration data at the maximum point of the combined acceleration (highly likely to be the lowest point of the arm) or the midpoint of the vector of the two minimum points calculated by the walking reference vector calculation unit 1022 Can be used. As the geomagnetic vector corresponding to the gravity vector, the maximum point can be used as in the gravity vector, or the average value between the two minimum points can be used. The azimuth reference vector is determined east or west according to the walking reference vector.

  The azimuth angle calculation unit 1024 derives an angle formed by the walking reference vector and the azimuth reference vector, and calculates an azimuth angle from the formed angle.

  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 1025 stores the azimuth angle θ in a predetermined time range with respect to the azimuth angle θ output from the azimuth angle calculation unit 1024, and the change before and after the azimuth angle θ is equal to or greater than a predetermined angle threshold. Remove.

  For example, as shown in Table 2 below, if only one data is swung more than the previous data, for example, 90 degrees (predetermined angle threshold) or more, the data is removed. Here, the subordinate angle is used to calculate the magnitude of the change in the azimuth angle θ. For example, when the previous azimuth angle θ is 5 degrees and the current azimuth angle θ is 355 degrees, the magnitude of the change in the azimuth angle θ is 10 degrees (not 350 degrees).

  Further, the correction unit 1025 preferably supplements the removed data with the average of the azimuth angles θ of the unit sections calculated before and after in time as shown in Table 3 below. In this calculation of the average, an inferior angle is used as in the case of obtaining the magnitude of change in the azimuth angle θ. For example, the average of 2 degrees and 358 degrees is 0 degrees (not 180 degrees).

  Further, the correction unit 1025 preferably averages the accumulated changes in the plurality of azimuth angles θ. Specifically, fluttering of the value of the azimuth angle θ can be suppressed by obtaining a moving average of the azimuth angles θ for the most recent steps. In the calculation of the moving average here, the subordinate angle is used as described above.

  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.

DESCRIPTION OF SYMBOLS 1 Mobile terminal 10 Processor memory 101 Walking timing determination part 102 Travel direction determination part 1021 Filter part 1022 Walking reference vector calculation part 1023 Direction reference vector calculation part 1024 Azimuth angle calculation part 1025 Correction part 103 Direction change determination part 104 Step length determination part 105 Movement amount integration unit 106 Current position determination unit 11 Geomagnetic sensor 12 Acceleration sensor 13 GPS unit 14 Map information storage unit 15 Display unit

Claims (8)

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 walking reference vector calculating means for calculating a walking reference vector that is a normal vector with respect to the acceleration surface based on the arm swinging motion;
An azimuth reference for deriving a gravity vector and a geomagnetic vector corresponding to the gravity vector from the acceleration data and the geomagnetic data, and calculating an azimuth reference vector that is a normal vector with respect to the azimuth reference plane of the gravity vector and the geomagnetic vector Vector calculation means;
Azimuth angle calculating means for calculating an azimuth angle of the traveling direction based on the walking reference vector and the azimuth reference vector;
The walking reference vector calculation means measures the time interval between the local minimum points in the change in the resultant acceleration with time, compares two adjacent time intervals, and compares the time intervals at the end of the long time interval. A portable terminal characterized in that the minimum point represents the front of the acceleration surface (front of the traveling direction), and the minimum point at the end of the short time interval represents the rear of the acceleration surface (rear of the traveling direction). The walking reference vector calculation means calculates the walking reference vector R as an outer product (R = B × F) of the acceleration vector B at the minimum point indicating the rear of the acceleration surface and the acceleration vector F at the minimum point indicating the front of the acceleration surface. (Or F × B))
The azimuth reference vector calculation means calculates the azimuth reference vector E by an outer product (E = G × M (or M × G)) of a gravity vector G and a geomagnetic vector M,
The azimuth calculating means calculates an angle α formed by both vectors from an inner product and a norm (vector magnitude) product using the azimuth reference vector E and the walking reference vector R, and the angle α formed by the following formula: Deriving the azimuth angle θ from the equation α = arccos ((E ・ R) / (| E || R |))
The mobile terminal according to claim 1. The azimuth angle calculating means calculates an outer product vector (E × R) of the azimuth reference vector E and the walking reference vector R, and the azimuth angle θ is an angle formed by an angle β formed by the outer product vector and the gravity vector G. Derived from α by the following equation: cos β ≧ 0: θ = α
cos β <0: θ = 360−α
The mobile terminal according to claim 2. 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. About the acceleration data and the geomagnetic data input to the reference vector deriving means,
5. The mobile 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,
6. The apparatus according to claim 1, further comprising 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. 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 walking reference vector calculating means for calculating a walking reference vector that is a normal vector with respect to the acceleration surface based on the arm swinging motion;
An azimuth reference for deriving a gravity vector and a geomagnetic vector corresponding to the gravity vector from the acceleration data and the geomagnetic data, and calculating an azimuth reference vector that is a normal vector with respect to the azimuth reference plane of the gravity vector and the geomagnetic vector Vector calculation means;
Azimuth angle calculating means for calculating an azimuth angle of the traveling direction based on the walking reference vector and the azimuth reference vector;
The walking reference vector calculation means measures the time interval between the local minimum points in the change in the resultant acceleration with time, compares two adjacent time intervals, and compares the time intervals at the end of the long time interval. A program for a portable terminal that causes a computer to function so that a local minimum point represents the front of the acceleration surface (front in the traveling direction) and a local minimum point at the end of the short time interval represents the rear of the acceleration surface (rear in the traveling direction) . 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 calculating a walking reference vector that is a normal vector for an acceleration surface based on an arm swinging motion;
A gravity vector and a geomagnetic vector corresponding to the gravity vector are derived from the acceleration data and the geomagnetic data, and a direction reference vector that is a normal vector with respect to the direction reference plane of the gravity vector and the geomagnetic vector is calculated. And the steps
A third step of calculating an azimuth angle of the traveling direction based on the walking reference vector and the azimuth reference vector;
The first step is to measure the time interval between the local minimum points in the change in the resultant acceleration with time, compare two adjacent time intervals, and determine the local minimum point at the end of the long time interval. Represents the front of the acceleration surface (front of the traveling direction), and the minimum point at the end of the short time interval represents the rear of the acceleration surface (rear of the traveling direction).

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