JP2005147696A - Attaching angle calculation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an attaching angle calculation system easily mounted on electronic apparatuses loaded on a moving body. <P>SOLUTION: The attaching angle calculation part 12 in the figure is electrically connected with a velocity sensor 2, an acceleration sensor 10 and an angular velocity sensor 11. The velocity sensor 2 detects the moving velocity of a moving body. The acceleration sensor 10 detects the acceleration of the moving body to a first axis and a second axis directions. The angular velocity sensor 11 detects the angular velocity of the moving body around a third axis. The attaching angle calculation part 12 acquires the moving velocity from the velocity sensor 2, the acceleration from the acceleration sensor 10 and the angular velocity from the angular velocity sensor 11. Then, the attaching angle calculation part 12 corrects the acquired acceleration by using the correction value stored in a correction value storage part 13. The attaching angle calculation part 12 also calculates the attaching angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an attachment angle calculation device, and more specifically to an attachment angle device that calculates an angle at which a casing of an electronic device mounted on a moving body is attached.

  Conventionally, a navigation system as an example of the electronic device typically includes an autonomous navigation sensor including an angular velocity sensor and an acceleration sensor in order to autonomously calculate a current position of a moving object such as a vehicle. Yes. However, each autonomous navigation sensor outputs a detection result including an error caused by each attachment angle unless it is attached in a correct posture to face a predetermined direction. Such an error propagates to the current position calculated by the navigation system, and as a result, the navigation system calculates the current position including the error.

As described above, the casing of the navigation system (hereinafter simply referred to as the casing) needs to be installed in a correct posture with respect to the moving body. However, installing the housing in the correct posture places a heavy burden on the installer, and conventionally a device that calculates the mounting angle of the housing and corrects the output of each autonomous navigation sensor (hereinafter referred to as mounting angle calculation). Have been proposed). In such a mounting angle calculation device, the mounting angle of the housing with respect to the roll direction, pitch direction, and yaw direction of the vehicle is calculated using output values obtained from an acceleration sensor that detects acceleration with respect to three axes. There are some (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-332415

  By the way, most navigation systems autonomously calculate the current position using an acceleration sensor that detects acceleration with respect to two axes. However, since the conventional mounting angle calculation device requires an acceleration sensor that detects acceleration with respect to three axes, it is mounted on a navigation system as an electronic device mounted on a moving body due to problems of manufacturing cost and / or installation space. There is a problem that it is difficult.

Further, from the viewpoint of manufacturing cost and / or installation space, when an acceleration sensor in three axis directions is mounted on the navigation system, it is possible to derive the mounting angle from the output value of such an acceleration sensor. preferable.
Therefore, an object of the present invention is to provide an attachment angle calculation device that can be easily mounted on an electronic device mounted on a moving body.

  In order to achieve the above object, one aspect of the present invention is an attachment angle calculation device that can be incorporated in an electronic device mounted on a moving body, and is an acceleration sensor capable of detecting acceleration in a biaxial direction of the moving body. Are connected to an angular velocity sensor that detects the angular velocity of the moving object, and a speed sensor that detects the velocity of the moving object. The acceleration detected by the acceleration sensor, the angular velocity detected by the angular velocity sensor, and the velocity sensor And an attachment angle calculation unit that calculates an angle at which the casing of the electronic device is attached based on the speed of the electronic device.

  According to the above situation, the mounting angle of the housing can be calculated using the acceleration in the biaxial direction. That is, the attachment angle calculation device can calculate the attachment angle of the housing using the output value of the biaxial acceleration sensor used in most navigation systems. This makes it possible to provide an attachment angle calculation device that can be easily mounted on a navigation system. In addition, even when an acceleration sensor that detects acceleration in the three-axis direction is mounted on the navigation system, the mounting angle calculation unit can be obtained from the acceleration in the two-axis direction that can be obtained from such an acceleration sensor. An attachment angle can be calculated. Therefore, even when a 3-axis acceleration sensor is mounted on the navigation system, it is not necessary to mount a 2-axis acceleration sensor on the mounting angle calculation device. An apparatus can be provided.

(Embodiment)
FIG. 1 is a block diagram showing a configuration of a mounting angle calculation device 1 according to an embodiment of the present invention. In FIG. 1, an attachment angle calculation device 1 is mounted on a navigation system as an example of an electronic device mounted on a moving body, and an angle at which a casing of the navigation system (hereinafter simply referred to as a casing) is attached. Is calculated. In order to calculate such an attachment angle, the attachment angle calculation device 1 includes an acceleration sensor 10, an angular velocity sensor 11, an attachment angle calculation unit 12, and a correction value storage unit 13.

  The acceleration sensor 10 detects the acceleration of the moving body in a predetermined biaxial direction. When such an acceleration sensor 10 is installed in a correct posture with respect to the moving body, the acceleration sensor 10 causes the acceleration in the traveling direction of the moving body and the acceleration in a direction orthogonal to the traveling direction of the moving body in the horizontal plane. Are detected. Hereinafter, as shown in FIGS. 2 and 3, the traveling direction of the moving body is referred to as a Y-axis direction, and the direction orthogonal to the traveling direction of the moving body in the horizontal plane is referred to as an X-axis direction. In the present embodiment, a direction that passes through the center of gravity of the moving body and is orthogonal to the X axis and the Y axis is referred to as a Z axis direction. Hereinafter, a coordinate system including these X axis, Y axis, and Z axis is referred to as a vehicle coordinate system. In the present embodiment, as a preferred example, the attachment angle calculation device 1 is described as including the biaxial acceleration sensor 10 as described above, but in the X axis direction and the Y axis direction instead of the acceleration sensor 10. There may be provided two uniaxial acceleration sensors for individually detecting the acceleration.

  The angular velocity sensor 11 detects the angular velocity around the Z axis of the moving body. When such an angular velocity sensor 11 is installed in a correct posture with respect to the moving body, the angular velocity sensor 11 detects the angular velocity (that is, the yaw rate) when the moving body rotates around the Z axis.

  The attachment angle calculation unit 12 typically includes a CPU, a ROM, and a RAM, and is electrically connected to the acceleration sensor 10, the angular velocity sensor 11, and the velocity sensor 2. The speed sensor 2 detects the moving speed of the moving body. When the moving body is a vehicle, the speed sensor 2 is preferably installed in a vehicle as an example of the moving body, and a vehicle speed pulse generating device that generates a vehicle speed pulse whose pulse period changes according to the traveling speed of the vehicle. It is. In the present embodiment, the speed sensor 2 is assumed to be originally installed in the vehicle as a preferred example. However, the present invention is not limited to this, and the attachment angle calculation device 1 may incorporate the speed sensor 2. The CPU executes a computer program stored in advance in the ROM using the RAM. During execution of the computer program, the attachment angle calculation unit 12 determines the attachment angle of the housing using at least each acceleration obtained from the acceleration sensor 10, the angular velocity obtained from the angular velocity sensor 11, and the moving velocity obtained from the speed sensor 2. calculate.

  The correction value storage unit 13 is configured, for example, as a part of the recording area of the RAM, and is electrically connected to the attachment angle calculation unit 12. Such a correction value storage unit 13 stores the acceleration output from the acceleration sensor 10 under a predetermined condition as a correction value. The attachment angle calculation unit 12 preferably calculates the attachment angle by further using the stored correction value in addition to the acceleration, angular velocity, and movement velocity of the moving body. In the present embodiment, the correction value storage unit 13 is described as an example of a RAM recording area. However, the present invention is not limited to this, and any storage device capable of recording information can be used. It may be configured with.

  Next, the process of the attachment angle calculation device 1 having the above configuration will be described in detail. First, the correction value storing process in the correction value storage unit 13 will be described. First, after the installation angle calculation device 1 is installed on the moving body, the acceleration sensor 10 is in the X-axis and Y-axis directions while the moving body is stationary at a place (for example, a flat road surface) that can be regarded as a substantially horizontal plane. The acceleration in both directions is detected. Each detected acceleration is stored in the correction value storage unit 13 as a correction value. Hereinafter, for convenience of explanation, a correction value in the X-axis direction is set as Xs0, and a correction value in the Y-axis direction is set as Ys0. Note that such storage processing is performed, for example, after the user determines that the moving body is stationary on a substantially horizontal plane and after the user performs a predetermined operation on the attachment angle calculation device 1. In addition, when the moving speed of the moving body is 0 and the inclination angle of the moving body with respect to the horizontal plane is 0, the above-described storage process may be performed.

  Here, FIG. 2 is a schematic diagram showing the attachment angle θ calculated by the attachment angle calculation device 1 shown in FIG. FIG. 3 is a schematic diagram showing the mounting angle φ calculated by the mounting angle calculation device 1. First, in FIG. 2, the attachment angle θ is an elevation angle of the housing with respect to the XY plane, in other words, indicates how many times the housing rotates around the X axis with respect to the correct posture of the housing. In FIG. 3, the attachment angle φ is the azimuth angle of the housing with respect to the YZ plane. In other words, it indicates how many times the housing rotates around the Z axis with respect to the correct posture of the housing. Due to such an angle shift, the acceleration sensor 10 does not detect acceleration in the Y-axis direction, but in a direction in which the Y-axis is rotated by an angle θ around the X-axis (see arrow Yp in FIG. 2). 2. Acceleration (see arrow Ap in FIG. 2) and / or acceleration (see arrow Ay in FIG. 3) in the direction (see arrow Yy in FIG. 3) in which the Y axis is rotated by an angle φ around the Z axis is detected. It will be. Here, the acceleration sensor 10 detects an acceleration including an error in the X-axis direction as in the case of the Y-axis. Further, the angular velocity sensor 11 also detects an angular velocity around the axis that is shifted due to an attachment error.

  Now, it is assumed that the moving body is traveling straight at an acceleration A on a horizontal plane in a state where the casing is inclined only around either the X axis or the Z axis. At this time, the acceleration detected by the acceleration sensor 10 is Ys. It should be noted here that Ys is the acceleration in the direction of one axis of the acceleration sensor 10 (the direction of the arrow Yp in FIG. 2 or the direction of the arrow Yy in FIG. 3). Under the above assumption, if Ys when the housing is tilted about the X axis is Ap (see FIG. 2), Ap is expressed by the following equation (1) using θ and φ. Further, when Ys in the case where the housing is tilted around the Z axis is Ay (see FIG. 3), Ay is expressed by the following expression (2). For convenience of explanation, the clockwise direction is the positive direction for rotation around the X axis and the Z axis. When the housing is not tilted in any direction, θ and φ are 0, so Ys = A.

次に、Ｘ軸回り及びＺ軸回りの双方に筐体が傾いている場合におけるＹｓ及びＸｓについて説明する。ここで、図４は、前述の車両座標系をＸ軸回りに角度θだけ回転させた座標系を示す模式図である。図４において、Ｚｐ軸及びＹｐ軸は、Ｚ軸及びＹ軸をＸ軸回りに角度θだけ回転させたものである。なお、Ｘｐ軸はＸ軸と同じである。また、図５は、Ｘ軸回りに角度θだけ回転させた車両座標系（図４参照）を、Ｚｐ軸回りに角度φだけさらに回転させた座標系を示す模式図である。図５において、Ｘｐｙ軸及びＹｐｙ軸は、図４に示すＸｐ軸及びＹｐ軸をＺｐ軸回りに角度θだけ回転させたものである。また、Ｚｐｙ軸は、図４のＺｐ軸と同じである。ここで、Ｘ軸回りに角度θだけ回転させるための回転行列をＲｘ（θ）、Ｚ軸回りに中心に角度φだけ回転させるための回転行列をＲｚ（φ）とすると、Ｘ軸及びＺ軸の両軸回りに回転した車両座標系（Ｘｐｙ，Ｙｐｙ，Ｚｐｙ）は、回転前の車両座標系（Ｘ，Ｙ，Ｚ）を用いて、下式（３）のように表される。

Next, Ys and Xs when the housing is tilted around both the X axis and the Z axis will be described. Here, FIG. 4 is a schematic diagram showing a coordinate system obtained by rotating the vehicle coordinate system described above by an angle θ around the X axis. In FIG. 4, a Zp axis and a Yp axis are obtained by rotating the Z axis and the Y axis by an angle θ around the X axis. The Xp axis is the same as the X axis. FIG. 5 is a schematic diagram showing a coordinate system in which the vehicle coordinate system (see FIG. 4) rotated around the X axis by an angle θ is further rotated by an angle φ around the Zp axis. In FIG. 5, an Xpy axis and a Ypy axis are obtained by rotating the Xp axis and the Yp axis shown in FIG. 4 by an angle θ around the Zp axis. The Zpy axis is the same as the Zp axis in FIG. Here, assuming that a rotation matrix for rotating around the X axis by an angle θ is Rx (θ) and a rotation matrix for rotating around the Z axis by an angle φ is Rz (φ), the X axis and the Z axis The vehicle coordinate system (Xpy, Ypy, Zpy) rotated around both axes is expressed by the following equation (3) using the vehicle coordinate system (X, Y, Z) before rotation.

  Here, Rz (φ) · Rx (θ) is expressed by the following equation (4).

  Assume that the moving body is moving at an acceleration A on a horizontal plane. Further, a vertically downward gravity acceleration G is applied to the moving body. Therefore, since the X-axis direction component of the acceleration applied to the moving body is 0, the Y-axis direction component is A, and the Z-axis direction component is -G, (X, Y, Z) in the above equation (3) Substituting = (0, A, -G) yields the following equation (5).

  Therefore, when the housing is installed with both the X axis and the Y axis inclined at an angle θ in the pitch direction and an angle φ in the yaw direction, the accelerations Xs and Ys output from the acceleration sensor 10 are respectively lower. It represents with Formula (6) and (7).

例えば、θ＝３０ｄｅｇ及びφ＝２０ｄｅｇの場合、加速度Ｘｓ及びＹｓは、下式（８）及び（９）のような値になる。

For example, in the case of θ = 30 deg and φ = 20 deg, the accelerations Xs and Ys have values as in the following expressions (8) and (9).

Xs = KxA = −0.2962A−0.1710G (8)
Ys = KyA = 0.8138A + 0.4698G (9)

  From the coefficient to the acceleration A and the gravitational acceleration component in the above equation (9), it can be seen that the sensitivity of the acceleration Ys output from the acceleration sensor 10 is lower than the actual acceleration A in the traveling direction.

  In addition, from the above equations (6) and (7), when the casing is mounted inclined in the pitch direction, that is, when θ ≠ 0, the gravitational acceleration component is removed to obtain accurate accelerations Xs and Ys. It is necessary to do. Hereinafter, the removal of the gravitational acceleration component is referred to as zero point correction. Next, such zero point correction will be described in detail.

  As described above, in the correction value storage unit 13, the output values Xs0 and Ys0 of the acceleration sensor 10 obtained under the condition that the moving body is stationary on a substantially horizontal plane are stored as correction values. Since the acceleration in the traveling direction is 0 under the above-described conditions, Xs0 and Ys0 are calculated by substituting A = 0 into the above equations (6) and (7), respectively. That is, Xs0 and Ys0 are values represented by the following expressions (10) and (11), respectively.

ここで、Ｘｄｒｉｆｔ及びＹｄｒｉｆｔは、例えば加速度センサ１０の内部誤差のように、重力加速度成分以外に起因する誤差である。

Here, X drift and Y drift are errors caused by components other than the gravitational acceleration component, for example, an internal error of the acceleration sensor 10.

  By using these Xs0 and Ys0, it is possible to correct the gravitational acceleration component included in the output value Xs and / or Ys of the acceleration sensor 10 in the form of zero point drift. Specifically, regarding the corrected acceleration, if the X-axis direction component is Xs ′ and the Y-axis direction component is Ys ′, Xs ′ and Ys ′ are expressed by the following equations (12) and (13), respectively. Is done.

Xs ′ = Xs + Xs0 (12)
Ys ′ = Ys + Ys0 (13)

  Next, a method for calculating the mounting angles θ and φ in the mounting angle calculation apparatus 1 will be described. As described above, it is assumed that the housing is installed at the center of gravity of the moving body. When the moving body turns as shown in FIG. 6, acceleration (so-called lateral G) in the X-axis direction is applied to the moving body. Furthermore, when each axis of the acceleration sensor 10 is tilted in the yaw direction, the acceleration sensor 10 is affected by the acceleration in the X-axis direction. If it is assumed that the mobile body turns in a steady circle and the side slip angle of the mobile body is very small, the acceleration Ax applied to the mobile body in the X-axis direction is given by the following equation (14).

Ax = V · γ (14)
Here, V is the moving speed of the moving body, and γ is the yaw rate of the moving body.

  Assuming that the acceleration in the moving direction of the moving body is zero, the influence of the acceleration Ax and the gravitational acceleration G on the acceleration sensor 10 is expressed by the following equation (3): (X, Y, Z) = (Ax, By substituting (0, -G), it is given by the following equation (15).

From the above equation (15), when the housing is not tilted in the yaw direction, that is, when φ = 0, the output value Ys (= Ypy) of the acceleration sensor 10 is influenced by the acceleration Ax due to the turning of the moving body. I understand that I do not receive it.
Next, a case where acceleration A in the traveling direction is applied to the moving body will be described. In this case, by substituting (X, Y, Z) = (Ax, A, −G) = (V · γ, A, −G) into the previous equation (3), Xs and Ys are respectively expressed by the following equations: It is expressed as (16) and (17).

上式（１６）及び（１７）から重力加速度成分を、前式（１２）及び（１３）を用いて消去した後に、Ｘｓ’をＸＳとおき、さらにＹｓ’をＹＳとおくと、ＸＳ及びＹＳはそれぞれ、次式（１８）及び（１９）のように表される。

After eliminating the gravitational acceleration component from the above equations (16) and (17) using the previous equations (12) and (13), if Xs ′ is set to XS and Ys ′ is set to YS, then XS and YS Are represented by the following equations (18) and (19), respectively.

上式（１８）及び（１９）を用いることにより、取り付け角度θ及びφを導出することが可能となる。つまり、上式（１８）又は（１９）からｃｏｓθを消去すると、次式（２０）が得られる。

By using the above equations (18) and (19), it is possible to derive the attachment angles θ and φ. That is, when cos θ is eliminated from the above equation (18) or (19), the following equation (20) is obtained.

また、ｃｏｓφとｓｉｎφとの間には、次式（２１）の関係が成り立つ。

Further, the relationship of the following equation (21) is established between cos φ and sin φ.

  From the above equations (20) and (21), φ is expressed by the following equation (22). Further, by substituting the calculated φ into the previous equation (16) and rearranging the equation, θ represented by the following equation (23) can be obtained.

  In the above formulas (22) and (23), V is the moving speed of the moving body and the output value of the speed sensor 2. γ is an angular velocity of the moving body, and is an output value of the angular velocity sensor 11. A is the acceleration in the traveling direction of the moving body, and is obtained by differentiating the output value V of the speed sensor 2. XS and YS are values obtained by correcting the output values Xs and Ys of the acceleration sensor 10, respectively. Therefore, φ and θ can be derived by substituting these known values into the above equations (22) and (23).

In addition, it is preferable to obtain | require attachment angle (phi) and (theta) in multiple times from a viewpoint of calculating | requiring the attachment angle with few deviations. Thereafter, a statistical method is performed using each of the attachment angles φ and θ, and thereby, the attachment angles φ ^* and θ ^* with less deviation are derived. As a specific example, the attachment angle calculation unit 12 repeats the above calculation process n times, and the average values of the n attachment angles φ and θ obtained as a result are derived as attachment angles φ ^* and θ ^* , respectively. Is done.

  Note that γ can be approximated to 0 when the moving body can be regarded as not turning. Therefore, if γ = 0 is substituted into the above equations (22) and (23), φ and θ can be obtained from the following equations (25) and (26).

  From the above equations (25) and (26), the attachment angles φ and θ can be derived only from the output values Xs and Ys of the acceleration sensor 10 and the moving speed from the speed sensor 2. The mounting angles φ and θ derived from the above equations (25) and (26) can be used as reference values for verifying the mounting angles φ and θ derived from the previous equations (22) and (23). . Besides the verification, the attachment angles φ and θ derived from the above equations (25) and (26) may be used as they are as the attachment angles of the housing.

  Next, with reference to the flowchart of FIG. 7, the process of the attachment angle calculation part 12 incorporating the above calculation methods is demonstrated. In FIG. 7, the attachment angle calculation unit 12 acquires the moving speed V from the speed sensor 2, the acceleration (Xs, Ys) from the acceleration sensor 10, and the angular speed γ from the angular speed sensor 11 (step S1).

  Next, the attachment angle calculation unit 12 corrects the acceleration (Xs, Ys) obtained in step S1 using the correction values (Xs0, Ys0) stored in the correction value storage unit 13 (step S2). . Specifically, as shown in the previous equation (12), Xs0 is added to Xs, whereby the attachment angle calculation unit 12 obtains Xs ′, that is, XS in the previous equation (18). Further, according to the previous equation (13), the attachment angle calculation unit 12 calculates Ys ′, that is, YS in the previous equation (19).

  Next, the attachment angle calculation unit 12 calculates the attachment angles φ and θ (step S3). Specifically, the attachment angle calculation unit 12 substitutes the moving velocity V and the angular velocity γ obtained in step S1 and the corrected accelerations XS and YS obtained in step S2 into the previous equation (22), and attaches them. The angle φ is calculated. Further, the attachment angle calculation unit 12 calculates the differential value of the moving speed V obtained in step S1 as the acceleration A, and then obtains the angular speed γ obtained in step S1, the acceleration A calculated this time, and the step S2. The corrected accelerations XS and YS are substituted into the previous equation (23). As a result, the attachment angle calculation unit 12 obtains the attachment angle θ.

Note that the attachment angle calculation unit 12 preferably repeats steps S1 to S3 a plurality of times, performs a statistical method using the plurality of attachment angles φ and θ obtained thereby, and attaches the attachment angles φ ^* and θ ^* may be derived.

  As described above, according to the mounting angle calculation device 1, the mounting angles φ and θ of the housing can be calculated from the acceleration in the biaxial direction. That is, the mounting angle calculation device 1 can calculate the mounting angles φ and θ of the housing using the output values of the biaxial acceleration sensor used in most navigation systems. This makes it possible to provide the attachment angle calculation device 1 that can be easily mounted on a navigation system.

  Note that even if an acceleration sensor that detects acceleration in the triaxial direction is mounted on the navigation system, the attachment angle calculation unit 12 can be obtained from the biaxial acceleration that can be obtained from such an acceleration sensor. Can calculate the mounting angle. This eliminates the need to mount an acceleration sensor that detects the acceleration in the biaxial direction on the attachment angle calculation device 1.

(Modification example)
In the first embodiment, it is assumed that the housing is installed at the center of gravity of the moving body. However, in practice, the housing may not be installed at the center of gravity of the vehicle. From the above viewpoint, it is necessary to correct the output value of the acceleration sensor 10 in accordance with the positional relationship between the housing and the position of the center of gravity. Hereinafter, with reference to the block diagram of FIG. 8, the attachment angle calculation device 3 according to the positional relationship between the housing and the center of gravity position will be described as a modified example of the attachment angle calculation device 1. In FIG. 8, the attachment angle calculation device 3 includes a position information storage unit 31 and an attachment angle calculation unit 32 instead of the attachment angle calculation unit 12 as compared with the attachment angle calculation device 1 illustrated in FIG. 1. Since there is no difference between the two attachment angle calculation devices 1 and 3 other than that, the same reference numerals are given to the components corresponding to the configuration shown in FIG. 1 in FIG.

  The position information storage unit 31 is typically configured by a non-volatile storage device, and stores distance information indicating the positional relationship of the housing with respect to a known center of gravity position. As shown in FIG. 9, the housing is installed at a position separated by a distance d in the X-axis direction and a distance L in the Y-axis direction in the vehicle coordinate system with the center of gravity as the origin. Here, d and L are arbitrary numbers. In such a case, the distance (L, d) from the origin is stored as the distance information.

  The attachment angle calculation unit 32 is electrically connected to the speed sensor 2 and typically includes a CPU, a ROM, and a RAM. The CPU executes a computer program stored in advance in the ROM using the RAM. During the execution of the computer program, the mounting angle calculation unit 32 is configured to display the distance information stored in the position information storage unit 31, the accelerations obtained from the acceleration sensor 10, the angular velocity obtained from the angular velocity sensor 11, and the vehicle speed obtained from the speed sensor 2. Is used to calculate the mounting angle of the housing.

  Next, the process of the attachment angle calculation device 3 having the above configuration will be described in detail. As shown in FIG. 9, the housing is separated from the center of gravity by distances d and L in the X-axis and Y-axis directions, respectively, in the vehicle coordinate system. When the mobile body turns, the output value of the acceleration sensor 10 is affected by the angular velocity γ generated by the turning. In this case, when the acceleration in the X-axis direction applied to the housing is set to ax, ax is expressed by the following equation (27).

Further, when the acceleration in the Y-axis direction applied to the housing is set to ay when the moving body turns, ay is expressed by the following equation (28).
ay = d · γ (28)

  In such a case, similarly to the derivation of the previous expressions (18) and (19), the accelerations XS and YS applied to the center of gravity in the X-axis and Y-axis directions are expressed by the following expressions (29) and (30). expressed.

  From the above equations (29) and (30), the following equation (31) is obtained by eliminating cos θ.

  From the above equation (30) and the previous equation (21), φ is expressed by the following equation (31). Further, by substituting the calculated φ into the above equation (30) and rearranging the equation, θ represented by the following equation (32) can be obtained.

  In the above formulas (31) and (32), V, L, γ, XS, YS, A, and d are all known as apparent from the foregoing.

Next, with reference to the flowchart of FIG. 10, the process of the attachment angle calculation part 32 incorporating the above calculation methods is demonstrated. In FIG. 10, the attachment angle calculation unit 32 acquires the moving speed V, acceleration (Xs, Ys), and angular velocity γ in the same manner as in step S1 (see FIG. 7) performed by the attachment angle calculation unit 12 (step S4). ).
Next, the attachment angle calculation unit 32 corrects the acceleration (Xs, Ys) obtained in step S4 in the same manner as step S2 in the attachment angle calculation unit 12 (step S5).
Further, the attachment angle calculation unit 32 acquires the distance (L, d) from the position information storage unit 31 (step S6).

  After execution of the above steps S4-S6, the attachment angle calculation unit 31 calculates the attachment angles φ and θ (step S7). Specifically, the attachment angle calculation unit 31 calculates the moving speed V and the angular speed γ obtained in step S4, the corrected acceleration XS and YS obtained in step S5, and the distance L obtained in step S6 from the previous equation. Substituting into (31), the mounting angle φ is calculated. Further, the attachment angle calculation unit 31 calculates the differential value of the moving speed V obtained in step S4 as the acceleration A, then the angular speed γ obtained in step S4, the acceleration A calculated this time, the correction obtained in step S5. The mounting angle θ is calculated from the accelerations XS and YS and the distance d obtained in step S6 according to the previous equation (32).

As in the case of the attachment angle calculation unit 12, the attachment angle calculation unit 32 performs statistical methods using the attachment angles φ and θ to derive the attachment angles φ ^* and θ ^* with less deviation. Also good.

As described above, according to the attachment angle calculation device 3, whether the center of gravity of the moving body and the case are at the same position or different positions, the attachment of the case can be performed from the acceleration in the biaxial direction. The angles φ and θ can be calculated. This makes it possible to provide the attachment angle calculation device 3 that can be easily mounted on the navigation system.
In this modified example, the center of gravity position of the moving object is a fixed value. However, since the center of gravity position of the moving object changes due to acceleration and deceleration of the moving object, the attachment angle calculation unit 32 is More preferably, the position of the center of gravity that changes with time is derived from parameters typified by acceleration and / or moving speed, and the distance (L, d) from the derived center of gravity position to the housing is derived.
(Application examples)

  FIG. 11 is a block diagram showing a configuration of the autonomous navigation sensor 4 incorporating the above-described attachment angle calculation device 1. In FIG. 11, the autonomous navigation sensor 4 is typically incorporated in a navigation system, and in addition to the attachment angle calculation device 1 connected to the speed sensor 2, an acceleration correction unit 41, an inclination angle calculation unit 42, an angular velocity correction. Unit 43 and azimuth angle calculation unit 44.

The acceleration correction unit 41 receives the accelerations Ys and Xs from the acceleration sensor 10 and further receives the attachment angles θ ^* and φ ^* from the attachment angle calculation unit 12. The acceleration correction unit 41 obtains the inertial acceleration A ^* in the Y-axis direction using the received accelerations Ys and Xs and the received mounting angles θ ^* and φ ^* . Specifically, when the parameter of V · γ is deleted from the previous equations (18) and (19), the following equation (33) for obtaining the inertia acceleration A ^* is obtained.

The acceleration correcting unit 41 derives the inertial acceleration A ^* by substituting the attachment angles θ ^* and φ ^* into the above equation (33). The acceleration correction unit 41 passes the inertial acceleration A ^* thus derived to the tilt angle calculation unit 42.

The inclination angle calculation unit 42 receives the moving speed V from the speed sensor 2 and further receives the inertial acceleration A ^* from the acceleration correction unit 42. From the received inertial acceleration A ^* and the moving speed V, the tilt angle calculation unit 42 calculates the tilt angle Θ indicating how much the surface on which the moving body is currently located is tilted with respect to the horizontal plane. Hereinafter, a specific method of calculating the inclination angle Θ will be described with reference to FIG. FIG. 12 is a schematic diagram showing a state where a vehicle as a moving body is moving on a road surface with an inclination angle Θ. As shown in FIG. 12, in the traveling direction of the moving body, in addition to the inertial acceleration A ^* , a gravitational acceleration G component GsinΘ in the slope direction is generated. Now, assuming that the acceleration obtained by differentiating the moving speed V from the speed sensor 2 is A, the following relational expression (34) is established between A ^* and A.

  Therefore, the inclination angle Θ is expressed by the following equation (35).

The tilt angle calculation unit 42 calculates the tilt angle Θ by substituting the received acceleration A ^* and the acceleration A that can be calculated by itself into the above equation (35). The tilt angle calculation unit 42 passes the tilt angle Θ calculated as described above to the angular velocity correction unit 43.
In addition to the inclination angle Θ, the angular velocity correction unit 43 receives the attachment angles φ and θ from the attachment angle calculation unit 12, and further receives the angular velocity γ from the angular velocity sensor 11. The angular velocity correction unit 43 corrects the received angular velocity γ using the received inclination angle Θ and attachment angles φ and θ. Specifically, the angular velocity desired to be acquired by the autonomous navigation sensor 4 is an angular velocity around the normal of the surface on which the moving object is currently located, but the axis of the angular velocity sensor 11 is determined by the mounting angles φ and θ, and the surface Depending on the inclination angle Θ, the direction of the normal is different. Therefore, if the angular velocity around the normal is γ ^* , γ ^* is expressed by the following equation (36).

The angular velocity correction unit 43 substitutes the received inclination angle Θ, attachment angles φ and θ, and angular velocity γ into the above equation (36), and derives the angular velocity γ ^* around the normal of the surface where the moving body is currently located. To the azimuth angle calculation unit 44.
The azimuth angle calculation unit 44 calculates the azimuth angle of the moving body by accumulating the received angular velocity γ ^* .

As described above, according to the autonomous navigation sensor 4, the accelerations Ys and Xs detected by the acceleration sensor 10 and the angular velocity γ detected by the angular velocity sensor 11 are corrected according to the attachment angles θ and φ, and more accurate. It is possible to derive the inertial acceleration A ^* and the angular velocity γ ^* .
In the application example described above, the autonomous navigation sensor 4 has been described as including the attachment angle calculation device 1, but may be configured to include the attachment angle calculation device 3.
Moreover, in the above application example, it demonstrated that the attachment angle calculation apparatus 1 shown in FIG. 11 outputs attachment angle (theta) ^* and (phi) ^* as a preferable example. However, the present invention is not limited to this, and the angle calculation device 1 may output the attachment angles θ and φ.

  The attachment angle calculation device according to the present invention has a feature of calculating the attachment angle of a housing using an output value of an acceleration sensor that detects acceleration in two directions at most, and is useful as a navigation system or the like.

The block diagram which shows the structure of the attachment angle calculation apparatus 1 which concerns on one Embodiment of this invention. The schematic diagram which shows the attachment angle (theta) calculated by the attachment angle calculation apparatus 1 shown in FIG. The schematic diagram which shows the attachment angle (phi) calculated by the attachment angle calculation apparatus 1 shown in FIG. Schematic diagram showing a coordinate system obtained by rotating the vehicle coordinate system shown in FIG. 2 or 3 around the X axis by an angle θ. Schematic diagram showing a coordinate system obtained by further rotating the vehicle coordinate system after rotation shown in FIG. 4 by an angle φ around the Zp axis. The schematic diagram which shows a mode that the vehicle as a moving body in which the attachment angle calculation apparatus 1 shown in FIG. 1 is installed turns. The flowchart which shows the process sequence of the attachment angle calculation part 12 shown in FIG. The block diagram which shows the structure of the attachment angle calculation apparatus 3 which concerns on the modification of the attachment angle calculation apparatus 1 shown in FIG. The schematic diagram which shows the positional relationship of the attachment angle calculation apparatus 3 shown in FIG. 8, and the gravity center position of a moving body. The flowchart which shows the process sequence of the attachment angle calculation apparatus 32 shown in FIG. The block diagram which shows the structure of the autonomous navigation sensor 4 incorporating the attachment angle calculation apparatus 1 shown in FIG. Schematic diagram showing the inclination angle Θ calculated by the inclination angle calculation unit 42 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,3 Attachment angle calculation apparatus 10 Acceleration sensor 11 Angular velocity sensor 12, 32 Attachment angle calculation part 13 Correction value storage part 31 Position information storage part 2 Speed sensor 4 Autonomous navigation sensor 41 Acceleration correction part 42 Inclination angle calculation part 43 Angular speed correction part 44 Azimuth calculation unit

Claims (9)

An attachment angle calculation device that can be incorporated into an electronic device mounted on a moving body,
An acceleration sensor capable of detecting acceleration in the biaxial direction of the moving body;
An angular velocity sensor for detecting an angular velocity of the moving body;
Connected to a speed sensor for detecting the speed of the moving body, based on the acceleration detected by the acceleration sensor, the angular speed detected by the angular speed sensor, and the speed detected by the speed sensor, An attachment angle calculation apparatus comprising: an attachment angle calculation unit that calculates an angle at which a housing of the electronic device is attached. A correction value storage unit that stores, as a correction value, an acceleration output from the acceleration sensor under a condition that the moving body is substantially in a horizontal plane;
The mounting angle calculation unit adds the correction value stored in the correction value storage unit to the acceleration output from the acceleration sensor, corrects the acceleration output from the acceleration sensor, and then corrects the acceleration of the housing. The attachment angle calculation device according to claim 1, wherein the attachment angle is calculated.   The attachment angle calculation device according to claim 2, wherein the attachment angle calculation unit further calculates an attachment angle of the casing by further using an acceleration obtained by differentiating a speed obtained from the speed sensor.   The attachment angle calculation device according to claim 1, wherein the attachment angle calculation unit further performs a statistical process on the attachment angle of the casing calculated by the attachment angle calculation unit.   The attachment angle calculation device according to claim 4, wherein the attachment angle calculation unit calculates the attachment angle of the casing a plurality of times and calculates an average value of all the calculated attachment angles. A position information storage unit that stores distance information indicating a distance from the center of gravity of the movable body to the housing;
The attachment position calculation device according to claim 1, wherein the attachment angle calculation unit calculates the attachment angle of the housing by further using distance information stored in the position information storage unit.   The mounting angle calculation unit derives the distance from the center of gravity position of the moving body to the housing from the acceleration and / or moving speed of the moving body and the distance information stored in the position information storage unit, The attachment angle calculation apparatus according to claim 6, wherein the attachment angle of the housing is calculated by further using the derived distance. An autonomous navigation sensor connected to a speed sensor for detecting the speed of a moving object,
An acceleration sensor for detecting the acceleration of the moving body;
An angular velocity sensor for detecting an angular velocity of the moving body;
Based on the acceleration detected by the acceleration sensor, the angular velocity detected by the angular velocity sensor, and the velocity detected by the velocity sensor, a casing of an electronic device mounted on the moving body is attached. An attachment angle calculation unit for calculating an angle;
An acceleration correction unit that calculates inertial acceleration of the moving body from the acceleration output from the acceleration sensor and the mounting angle of the housing output from the mounting angle calculation unit;
An inclination angle calculation unit for calculating an inclination angle of a surface on which the movable body is currently located from the velocity output from the speed sensor and the inertial acceleration output from the acceleration correction unit;
An angular velocity correction unit that corrects the angular velocity output from the angular velocity sensor using the inclination angle output from the inclination angle calculation unit and the attachment angle of the housing output from the attachment angle calculation unit;
An autonomous navigation sensor comprising: an azimuth angle calculation unit that calculates an azimuth angle of the moving body from the angular velocity corrected by the angular velocity correction unit. A method of calculating an attachment angle of a casing of an electronic device mounted on a moving body,
First step of acquiring acceleration from an acceleration sensor installed on the moving body, acquiring angular velocity from an angular velocity sensor installed on the moving body, and further acquiring speed from a speed sensor installed on the moving body. When,
A mounting angle calculation method comprising: a second step of calculating a mounting angle of the casing based on the acceleration, angular velocity, and speed of the moving body acquired in the first step.

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