JP2012037405A - Sensor device, electronic apparatus, and offset correction method of angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor device that self-determines correction timing and corrects an offset of an angular velocity sensor, an electronic apparatus, and an offset correction method of the angular velocity sensor.SOLUTION: An initial state detection part 210 calculates acceleration based upon an output of the angular velocity sensor, and detects as an initial state a state in which the calculated acceleration is substantially equal to gravity acceleration. An angular velocity calculation part 220 calculates axis vectors in respective detection axis directions in the initial state based upon attitude information in the initial state, and calculates an angular velocity of rotation on an arbitrary axis based upon the axis vectors, acceleration components in the respective detection axis directions, and temporal changes of the acceleration components. An angular velocity determination part 230 determines that an angular velocity applied to the angular velocity sensor is 0 when the angular velocity that the angular velocity calculation parts 220 calculates is substantially 0. An offset correction part 40 corrects an offset of the output of the angular velocity sensor when it is determined that the angular velocity applied to the angular velocity sensor is 0.

Description

  The present invention relates to a sensor device, an electronic apparatus, and an offset correction method for an angular velocity sensor.

  In recent years, various systems and electronic devices using sensor modules that detect angular velocities and attitude angle detection units that detect attitude angles have been used. In these systems and electronic devices, it is impossible to correctly detect that the camera is stationary at rest unless the bias offset (zero offset) of the gyro sensor (angular velocity sensor) is excluded. The most important issue is how to eliminate the bias offset.

  Conventionally, bias offset is measured during product manufacturing, etc., and bias data is corrected by writing correction data in a nonvolatile memory element incorporated in the product, or a stationary state is detected when the product is used. Thus, a method for performing offset calibration is realized. The former method can correct the initial variation of the bias offset, but cannot cope with the bias variation at the time of user use due to temperature variation or the like. On the other hand, in the latter method, a bias offset occurring in the user's usage environment can be corrected for calibration in the usage environment. For this reason, it is possible to correct fluctuations from the correction at the time of manufacture and temperature fluctuations that cannot be corrected by the linear function.

JP 2010-019751 A Japanese Patent No. 4314566 Japanese Patent No. 2857091

  However, all the methods for calibrating the bias offset in the usage environment are performed in conjunction with the application function. For example, in the method of Patent Document 1, the player draws a bow, in the method of Patent Document 2, calibration is performed at the time of charging the vacuum cleaner or when the direction is changed, and in the method of Patent Document 3, calibration is performed when the navigation device is activated. The timing for performing calibration is determined. That is, it is realized as a calibration correction algorithm incorporated in the application, and the sensor unit alone does not have a function for determining the timing of calibration. For this reason, it takes time for an application developer to consider the appropriate timing of calibration correction and create a correction algorithm.

  The present invention has been made in view of the above problems, and according to some aspects of the present invention, a sensor device capable of self-determining the correction timing and performing offset correction of the angular velocity sensor, An offset correction method for an electronic device and an angular velocity sensor can be provided.

  (1) The present invention is a sensor device including an angular velocity sensor and three or more acceleration sensors, and whether or not the angular velocity applied to the angular velocity sensor is 0 based on the output of the acceleration sensor. A sensor device comprising: a determination unit that determines; and an offset correction unit that corrects an offset of an output of the angular velocity sensor when the determination unit determines that the angular velocity is zero.

  Since the angular velocity is not applied to the angular velocity sensor if the sensor device is stopped, the output voltage of the angular velocity sensor at this time becomes zero point voltage. Therefore, at this timing, the offset of the zero point voltage can be corrected appropriately. According to the present invention, the timing at which the angular velocity is not applied to the angular velocity sensor can be detected based on the output of the acceleration sensor, so that the offset of the angular velocity sensor can be automatically corrected at that timing. That is, according to the present invention, the offset of the angular velocity sensor can be corrected by the sensor device alone regardless of the application function. Therefore, if this sensor device is used, it is not necessary to implement a correction algorithm on the application side as in the conventional method, and the zero point offset of the angular velocity sensor can be corrected without imposing a load on the user.

  Further, according to the present invention, it is possible to detect and correct the fluctuation of the zero point of the angular velocity sensor under the usage environment.

  (2) In this sensor device, the determination unit determines whether or not an angular velocity applied to the angular velocity sensor is zero based on a temporal change of an acceleration component in each detection axis direction of the acceleration sensor. May be.

  (3) In this sensor device, the determination unit calculates an acceleration applied to the sensor device based on the output of the acceleration sensor, and detects a state where the calculated acceleration and the gravitational acceleration substantially coincide with each other as an initial state. Based on the attitude information of the sensor device in the initial state and the detection unit, the axis vector in each detection axis direction in the initial state is calculated, and the time variation of the axis vector, the acceleration component in each detection axis direction, and the acceleration component And the angular velocity calculating unit that calculates the angular velocity at which the sensor device rotates about an arbitrary axis, and the angular velocity calculated by the angular velocity calculating unit is substantially zero, the angular velocity applied to the angular velocity sensor is zero. And an angular velocity determination unit that determines that.

  According to this sensor device, even when a small centrifugal force that cannot be detected by the acceleration sensor is applied, the angular velocity applied to the angular velocity sensor can be detected by monitoring the temporal change in the acceleration component from the initial state. Therefore, the determination accuracy of the timing for performing the offset correction of the angular velocity sensor can be improved.

  (4) In this sensor device, the angular velocity determination unit determines that the angular velocity applied to the angular velocity sensor is zero when the angular velocity calculated by the angular velocity calculation unit is substantially zero for a predetermined time. May be.

  In this way, it is discriminated whether the angular velocity is continuously applied to the sensor device for a predetermined time or whether the angular velocity is instantaneously zero, and the offset correction of the angular velocity sensor is performed only in the former case. be able to.

  (5) In this sensor device, the determination unit substantially matches an acceleration calculation unit that calculates acceleration applied to the sensor device based on an output of the acceleration sensor, and an acceleration calculated by the acceleration calculation unit and a gravitational acceleration. In this case, an angular velocity determination unit that determines that the angular velocity applied to the angular velocity sensor is 0 may be included.

  When the sensor device is in a rotating state, the angular velocity sensor detects the angular velocity, and therefore, appropriate offset correction cannot be performed at that timing. On the other hand, if a centrifugal force acts on the sensor device, the acceleration sensor detects the centrifugal acceleration generated by the centrifugal force, so the detected acceleration does not coincide with the gravitational acceleration. Therefore, according to this sensor device, the offset of the angular velocity sensor can be corrected at an appropriate timing when centrifugal force is not applied by a simple calculation process that determines whether or not the acceleration detected by the acceleration sensor matches the gravitational acceleration. Can do.

  (6) In this sensor device, the angular velocity determination unit determines that the angular velocity applied to the angular velocity sensor is 0 when a state in which the acceleration calculated by the acceleration calculation unit and the acceleration of gravity substantially coincide with each other continues for a predetermined time. You may make it do.

  In this way, whether the centrifugal force is continuously applied to the sensor device for a predetermined time or whether the centrifugal force is instantaneously zero is distinguished, and the angular velocity sensor offset correction is performed only in the former case. Can be.

  (7) In this sensor device, the determination unit calculates an acceleration applied to the sensor device based on an output of the acceleration sensor, and detects an initial state where the calculated acceleration and the gravitational acceleration substantially coincide with each other. Based on the attitude information of the sensor device in the initial state and the detection unit, the axis vector in each detection axis direction in the initial state is calculated, and the time variation of the axis vector, the acceleration component in each detection axis direction, and the acceleration component An angular velocity calculation unit that calculates an angular velocity at which the sensor device rotates about an arbitrary axis, a determination mode control unit that switches between a first determination mode and a second determination mode according to a control signal, and the first In the first determination mode, it is determined that the angular velocity applied to the angular velocity sensor is zero when the initial state detection unit detects the initial state. And, in the second determination mode, may include a angular velocity determination unit determines that the angular velocity is zero applied to the angular velocity sensor when an angular velocity where the velocity calculation unit has calculated is substantially zero.

  In this way, the determination accuracy of the offset correction timing of the angular velocity sensor can be changed depending on which of the first determination mode and the second determination mode is used according to the application using the sensor device. it can. That is, if the first determination mode is set, the determination is simple based on the detection of the centrifugal force. If the second determination mode is set, the sensor device can be applied even when a minute centrifugal force that cannot be detected by the acceleration sensor is applied. It can be determined whether or not the applied angular velocity is zero.

  (8) In this sensor device, in the first determination mode, the angular velocity determination unit has an angular velocity applied to the angular velocity sensor of 0 when the initial state detection unit detects the initial state for a predetermined time. In the second determination mode, it is determined that the angular velocity applied to the angular velocity sensor is zero when the angular velocity calculated by the angular velocity calculator is substantially zero for a predetermined time. Good.

  In this way, in the first determination mode, it is distinguished whether the centrifugal force is continuously applied to the sensor device for a predetermined time or whether the centrifugal force is instantaneously zero, and only in the former case, the angular velocity is determined. Sensor offset correction can be performed. In the second determination mode, whether the angular velocity is continuously applied to the sensor device for a predetermined time or whether the angular velocity is instantaneously zero is discriminated, and the offset correction of the angular velocity sensor is performed only in the former case. Can be.

  (9) The present invention is an electronic device including any one of the sensor devices described above.

  (10) The present invention provides an angular velocity sensor offset correction method for correcting an offset of an output of the angular velocity sensor in a sensor device including an angular velocity sensor and three or more acceleration sensors, and the output of the acceleration sensor And determining whether the angular velocity applied to the angular velocity sensor is zero, and correcting the offset of the output of the angular velocity sensor when the angular velocity is determined to be zero in the determining step. An offset correction method for an angular velocity sensor, including an offset correction step.

  (11) In this angular velocity sensor offset correction method, the determination step calculates an acceleration applied to the sensor device based on an output of the acceleration sensor, and sets a state in which the calculated acceleration and gravity acceleration substantially coincide with each other as an initial state. An initial state detecting step to detect, and an axis vector in each detection axis direction in the initial state is calculated based on posture information of the sensor device in the initial state, the axis vector, an acceleration component in each detection axis direction, and the acceleration An angular velocity calculating step for calculating an angular velocity at which the sensor device rotates about an arbitrary axis based on a temporal change of a component, and an angular velocity applied to the angular velocity sensor when the angular velocity calculated in the angular velocity calculating step is substantially zero And an angular velocity determination step of determining that is 0.

The schematic block diagram of the sensor apparatus of 1st Embodiment. The figure for demonstrating the determination principle of the timing which performs the offset correction process of 1st Embodiment. The flowchart figure which shows the 1st example of the offset correction process of 1st Embodiment. The flowchart figure which shows the 2nd example of the offset correction process of 1st Embodiment. The schematic block diagram of the sensor apparatus of 2nd Embodiment. The figure for demonstrating the Euler angle of a Z-X-Z type | system | group. The flowchart figure which shows the 1st example of the offset correction process of 2nd Embodiment. The flowchart figure which shows the 2nd example of the offset correction process of 2nd Embodiment. The schematic block diagram of the sensor apparatus of 3rd Embodiment. The flowchart figure which shows the 1st example of the offset correction process of 3rd Embodiment. The flowchart figure which shows the 2nd example of the offset correction process of 3rd Embodiment. FIG. 3 is a functional block diagram illustrating a configuration example of an electronic apparatus according to the embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Sensor device (1) First embodiment [Configuration]
FIG. 1 is a schematic configuration diagram of a sensor device according to the first embodiment.

  As shown in FIG. 1, the sensor device 1A of the first embodiment includes three acceleration sensors 10x, 10y, and 10z. The acceleration sensors 10x, 10y, and 10z are fixedly arranged so that the detection axes are orthogonal to each other, and output a detection signal of a DC voltage corresponding to the magnitude of acceleration applied in the respective detection axis directions.

  The sensor device 1A includes three angular velocity sensors (gyro sensors) 20x, 20y, and 20z. The angular velocity sensors 20x, 20y, and 20z are fixedly arranged so that the detection axes are orthogonal to each other, and output a detection signal of a DC voltage corresponding to the magnitude of the angular velocity applied around each detection axis.

  In the present embodiment, the acceleration sensor 10x and the angular velocity sensor 20x are arranged so that their detection axes coincide with each other, and this detection axis is taken as the x-axis. Similarly, the acceleration sensor 10y and the angular velocity sensor 20y are arranged so that their detection axes coincide with each other, and this detection axis is taken as the y-axis. Similarly, the acceleration sensor 10z and the angular velocity sensor 20z are arranged so that their detection axes coincide with each other, and this detection axis is taken as the z-axis.

  The sensor device 1A includes a determination unit 30. The determination unit 30 determines whether or not the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is 0 based on the outputs of the acceleration sensors 10x, 10y, and 10z.

In the present embodiment, the determination unit 30 includes an acceleration calculation unit 110. The acceleration calculation unit 110 calculates the acceleration applied to the sensor device 1A based on the outputs of the acceleration sensors 10x, 10y, and 10z. In the present embodiment, the acceleration calculation unit 110 samples the output voltages of the acceleration sensors 10x, 10y, and 10z at a predetermined cycle, and performs acceleration components in the x-axis, y-axis, and z-axis directions obtained by A / D conversion. The sum of squares g _x ² + g _y ² + g _z ² of g _x , g _y , and g _z is calculated.

In the present embodiment, the determination unit 30 includes an angular velocity determination unit 120. The angular velocity determination unit 120 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero when the acceleration calculated by the acceleration calculation unit 110 and the gravitational acceleration G substantially match. In the present embodiment, the angular velocity determination unit 120 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is 0 if g _x ² + g _y ² + g _z ² = G ² .

  For example, the angular velocity determination unit 120 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is 0 when the acceleration calculated by the acceleration calculation unit 110 and the gravitational acceleration G substantially coincide with each other for a predetermined time. You may do it.

  The sensor device 1 </ b> A includes an offset correction unit 40. The offset correction unit 40 corrects the offset (zero point offset) of the output of the angular velocity sensors 20x, 20y, and 20z when the determination unit 30 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero. In the present embodiment, the angular velocity sensors 20x, 20y, and 20z have a zero point voltage adjustment function, and the offset correction unit 40 is based on the output voltage of the angular velocity sensors 20x, 20y, and 20z at the timing of the offset correction processing and the specifications. By supplying a zero point adjustment signal corresponding to an error from the zero point voltage to the angular velocity sensors 20x, 20y, and 20z, these output voltages are made to coincide with the specified zero point voltages.

As described above, the sensor device 1A according to this embodiment includes the sum of squares of acceleration (g _x ² + g _y ² + g _z ² ) obtained sequentially by periodically sampling the output voltages of the acceleration sensors 10x, 10y, and 10z. The offsets (zero point offsets) of the outputs of the angular velocity sensors 20x, 20y, and 20z are automatically corrected at the timing when the gravitational acceleration squares (G ² ) coincide.

[Judgment principle of offset correction timing]
Next, the determination principle of the timing for performing the offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment will be described with reference to FIGS. 2 (A) and 2 (B).

When the sensor device 1A is used on the earth, gravity is always applied to the sensor device 1A. Therefore, if the sensor device 1A is stopped or is moving at a constant linear velocity, as shown in FIG. 2A, the acceleration sensors 10x, 10y, and 10z detect only gravitational acceleration. In FIG. 2A, g _x , g _y , and g _z represent acceleration components in the x-axis, y-axis, and z-axis directions, and G represents gravity acceleration. That is, the vector sum of g _x , g _y , and g _z coincides with G, and the following expression (1) is established.

On the other hand, if the sensor device 1A rotates about an arbitrary axis, centrifugal force is applied. Therefore, as shown in FIG. 2 (B), the acceleration sensors 10x, 10y, and 10z obtain the gravitational acceleration and the centrifugal acceleration due to the centrifugal force. To detect. In FIG. 2B, g _x , g _y , and g _z represent acceleration components in the x-axis, y-axis, and z-axis directions, G represents gravitational acceleration, R represents centrifugal acceleration, and n represents a rotation axis. Yes. That is, the vector sum of g _x , g _y , and g _z coincides with the vector sum of G and R, and the following equation (2) is established.

  Here, if the sensor device 1A is stopped or is moving at a constant linear velocity (unless it is rotating), no angular velocity is applied to the sensor device 1A. Therefore, the angular velocity sensors 20x, 20y, and 20z are all zero points. Output voltage. Therefore, offset correction (zero point correction) of the angular velocity sensors 20x, 20y, and 20z can be performed when Expression (1) is established.

  On the other hand, if the sensor device 1A is rotating about an arbitrary axis, the angular velocity of this rotational motion is added to the sensor device 1A, and the angular velocity sensors 20x, 20y, and 20z are x-axis components of this angular velocity, y-axis. The component and the z-axis component are detected. Therefore, since at least one output voltage of the angular velocity sensors 20x, 20y, and 20z does not become a zero point voltage, offset correction (zero point correction) is performed when Expression (2) is satisfied (Expression (1) is not satisfied). I can't.

Therefore, the angular velocity determination unit 120 determines whether or not the angular velocity applied to the sensor device 1A is 0 depending on whether or not the equation (1) is satisfied, and controls the timing of the offset correction processing of the angular velocity sensors 20x, 20y, and 20z. . However, actually, even if the sensor device 1A stops or moves at a constant speed due to environmental factors such as output offset of the acceleration sensors 10x, 10y, and 10z and noise in the environment where the sensor device 1A is used, the acceleration sensors 10x and 10y It is assumed that the acceleration g detected by 10z does not slightly match the gravitational acceleration G. Therefore, the angular velocity determination unit 120, for example, if the difference between g _x ² + g _y ² + g _z ² and G ² is a small value Δ or less, that is, G ² −Δ ≦ g _x ² + g _y ² + g _z ² ≦ G. ^{If 2} + Δ is satisfied, it may be determined that the angular velocity applied to the sensor device 1A is zero. The minute value Δ is set to an appropriate value depending on the specification on the application side using the sensor device 1A.

[Offset correction processing]
FIG. 3 is a flowchart showing a first example of offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment.

First, the acceleration calculation unit 110 samples detection signals from the acceleration sensors 10x, 10y, and 10z, and calculates acceleration components g _x , g _y , and g _z in the x-axis, y-axis, and z-axis directions (step S10).

Next, the acceleration calculation unit 110 calculates g _x ² + g _y ² + g _z ² (step S20).

Next, the angular velocity determination unit 120 determines whether or not g _x ² + g _y ² + g _z ² and G ² match (step S30), and when g _x ² + g _y ² + g _z ² ≠ G ² ( Step S30 N), Steps S10 and S20 are performed again.

On the other hand, if g _x ² + g _y ² + g _z ² = G ² (Y in step S30), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S40).

  FIG. 4 is a flowchart showing a second example of offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment. 4, steps that perform the same processing as in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  First, the angular velocity determination unit 120 starts measuring the predetermined time T1 (step S2).

Next, after the acceleration calculation unit 110 performs the processes of steps S10 and S20, the angular velocity determination unit 120 determines whether g _x ² + g _y ² + g _z ² and G ² match (step S30). When g _x ² + g _y ² + g _z ² ≠ G ² (N in step S30), the angular velocity determination unit 120 starts measurement of the predetermined time T1 again (step S2), and the acceleration calculation unit 110 performs steps S10 and S20. Repeat the process.

On the other hand, if g _x ² + g _y ² + g _z ² = G ² (Y in step S30), the angular velocity determination unit 120 determines whether or not a predetermined time T1 has elapsed since the measurement was started in step S2. However, if the predetermined time T1 has not elapsed (N in step S32), the processes of steps S10, S20, and S30 are repeated until the predetermined time T1 has elapsed. However, if g _x ² + g _y ² + g _z ² ≠ G ^{2 in} the determination process in step S30 before the predetermined time T1 has elapsed, the angular velocity determination unit 120 starts measuring the predetermined time T1 again.

  When the predetermined time T1 has elapsed (Y in step S32), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S40).

  In this way, it is distinguished whether the centrifugal force is continuously applied to the sensor device 1A for a predetermined time T1 or whether the centrifugal force is instantaneously zero, and only in the former case, the angular velocity sensors 20x, 20y are distinguished. , 20z offset correction can be performed.

  According to the sensor device of the first embodiment described above, the angular velocity can be determined at an appropriate timing when centrifugal force is not applied by a simple calculation process that determines whether or not the acceleration detected by the acceleration sensor matches the gravitational acceleration. The sensor offset can be corrected. That is, according to the sensor device of the first embodiment, the offset of the angular velocity sensor can be corrected by the sensor device alone regardless of the application function. Therefore, if this sensor device is used, it is not necessary to implement a correction algorithm on the application side as in the conventional method, and the zero point offset of the angular velocity sensor can be corrected without imposing a load on the user.

  Further, according to the sensor device of the first embodiment, it is possible to detect and correct the fluctuation of the zero point of the angular velocity sensor under the usage environment. Therefore, in some cases, it is not necessary to perform an offset adjustment of the angular velocity sensor before shipping or to write temperature characteristic correction data in the storage element. Furthermore, since the offset correction amount of the angular velocity sensor can be adjusted according to the use environment, the offset correction of the angular velocity sensor can be performed in response to a temperature change. In particular, even if there is correction data for temperature characteristics, it is possible to cope with non-linear temperature changes that are difficult to correct.

(2) Second Embodiment [Configuration]
FIG. 5 is a schematic configuration diagram of the sensor device of the second embodiment. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  As shown in FIG. 5, the sensor device 1B of the second embodiment includes three acceleration sensors 10x, 10y, 10z, three angular velocity sensors (gyro sensors) 20x, 20y, 20z, three geomagnetic sensors 60x, 60y and 60z are included. The geomagnetic sensors 60x, 60y, and 60z are arranged so that the detection axes (x axis, y axis, and z axis) are orthogonal to each other, and DC corresponding to the magnitude of the geomagnetism applied in the respective detection axis directions. Outputs voltage detection signal.

  In the present embodiment, the acceleration sensor 10x, the angular velocity sensor 20x, and the geomagnetic sensor 60x are arranged so that their detection axes coincide with each other, and this detection axis is taken as the x-axis. Similarly, the acceleration sensor 10y, the angular velocity sensor 20y, and the geomagnetic sensor 60y are arranged so that their detection axes coincide with each other, and this detection axis is taken as the y-axis. Similarly, the acceleration sensor 10z, the angular velocity sensor 20z, and the geomagnetic sensor 60z are arranged such that their detection axes coincide with each other, and this detection axis is taken as the z-axis.

  In the present embodiment, an orthogonal coordinate system having the x, y, and z axes as three coordinate axes is referred to as a sensor coordinate system. On the other hand, an orthogonal coordinate system using three orthogonal coordinate axes (X axis, Y axis, and Z axis) fixed in space is referred to as an absolute coordinate system. The X, Y, and Z axes of the absolute coordinate system are defined, for example, so that the positive direction of the X axis is north, the positive direction of the Y axis is west, and the positive direction of the Z axis is coincident with the direction of gravity. The

  The sensor device 1B includes an attitude information detection unit 70. The posture information detection unit 70 calculates the current posture information of the sensor device 1B based on the detection signals of the acceleration sensors 10x, 10y, 10z, the angular velocity sensors 20x, 20y, 20z, and the geomagnetic sensors 60x, 60y, 60z.

  In the present embodiment, the posture of the sensor device 1B is expressed by the Euler angle of the ZXZ system with reference to a state in which the absolute coordinate system (XYZ coordinate system) and the sensor coordinate system (xyz coordinate system) match. As shown in FIG. 6A, the Euler angle of the ZXZ system is converted into an X′Y′Z ′ coordinate system obtained by rotating the absolute coordinate system (XYZ coordinate system) by an angle φ around the Z axis. Next, the X'Y'Z 'coordinate system is converted into an X "Y" Z "coordinate system rotated by an angle θ around the X' axis, and finally X" Y "Z" When the coordinate system is converted to the X '' 'Y' '' Z '' 'coordinate system rotated by the angle ψ around the Z' 'axis, the X' '' Y '' 'Z' '' coordinate system is the sensor (Φ, θ, ψ) when matching with the coordinate system (xyz coordinate system). In the present embodiment, the Euler angles (φ, θ, ψ) of the Z-X-Z system are referred to as posture angles (φ, θ, ψ).

  That is, in this embodiment, the posture information detection unit 70 outputs posture angle (φ, θ, ψ) information as posture information.

  The sensor device 1B includes a determination unit 50. The determination unit 50 determines whether or not the angular velocities applied to the angular velocity sensors 20x, 20y, and 20z are zero based on the outputs of the acceleration sensors 10x, 10y, and 10z.

In the present embodiment, the determination unit 50 includes an initial state detection unit 210. The initial state detection unit 210 calculates an acceleration applied to the sensor device 1A based on the outputs of the acceleration sensors 10x, 10y, and 10z, and detects a state in which the calculated acceleration and the gravitational acceleration G substantially coincide with each other as an initial state. In the present embodiment, the initial state detection unit 210 samples the output voltages of the acceleration sensors 10x, 10y, and 10z at a predetermined cycle, and performs acceleration in the x-axis, y-axis, and z-axis directions obtained by A / D conversion. The sum of squares g _x ² + g _y ² + g _z ² of the components g _x , g _y , and g _z is calculated, and a state of g _x ² + g _y ² + g _z ² = G ² is detected as an initial state.

However, actually, even if the sensor device 1B stops or moves at a constant speed due to environmental factors such as an output offset of the acceleration sensors 10x, 10y, and 10z and noise in the environment where the sensor device 1B is used, the acceleration sensors 10x and 10y It is assumed that the acceleration g detected by 10z does not slightly match the gravitational acceleration G. Therefore, the initial state detection unit 210, for example, if the difference between g _x ² + g _y ² + g _z ² and G ² is a small value Δ or less, that is, G ² −Δ ≦ g _x ² + g _y ² + g _z ² ≦ The initial state is detected when G ² + Δ is satisfied. The minute value Δ is set to an appropriate value according to the specification on the application side using the sensor device 1B.

Here, when the centrifugal acceleration R shown in FIG. 2B is large to some extent, g _x ² + g _y ² + g _z ² = G ² does not hold, so that the initial state detection unit 210 detects the initial state. However, when the centrifugal acceleration R is extremely small, it is assumed that the initial state is detected by the initial state detection unit 210. Therefore, as described below, when the initial state is detected by the initial state detection unit 210, the determination unit 50 monitors whether or not the actual angular velocity ω is zero by monitoring subsequent changes in the acceleration detection component. Determine whether.

Therefore, in this embodiment, the determination unit 50 includes an angular velocity calculation unit 220. The angular velocity calculation unit 220 calculates axis vectors in the x-axis, y-axis, and z-axis directions in the initial state based on the attitude information of the sensor device 1B in the initial state, and the axis vectors and the x-axis, y-axis, and z-axis directions The angular velocity ω at which the sensor device 1B rotates around an arbitrary axis is calculated based on the acceleration component of the sensor and the time change of the acceleration component. In the present embodiment, the angular velocity calculation unit 220 uses the unit vectors a _x ^R and a _{y in the} x-axis, y-axis, and z-axis directions as axis vectors according to expressions (7), (8), and (9) described later. ^{R 1} and a _z ^R are calculated. Further, the angular velocity calculation unit 220 includes D ₁ including acceleration components g _x , g _y , and g _z detected by the acceleration sensors 10 _x , 10 _y , and 10 _{z according} to expressions (24), (25), and (26) described later. , D ₂ and D ₃ are calculated. Furthermore, the angular velocity calculation unit 220 calculates first-order derivatives (actually first-order differences) and second-order derivatives (actually second-order differences) of D ₁ , D ₂ , and D ₃ . The angular velocity calculating unit 220, the unit vector ^{_a x} _{R, a} y _R, and _a ^{z _R,} and D _1, D 2, _{D 3,} and the first derivative of the _{D 1, D 2, D 3} , D 1, Using the second derivative of D ₂ and D ₃ , ω ² is calculated by the equation (40) described later.

In the present embodiment, the determination unit 50 includes an angular velocity determination unit 230. The angular velocity determination unit 230 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero when the angular velocity calculated by the angular velocity calculation unit 220 is approximately zero. In the present embodiment, the angular velocity determination unit 230 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero if ω ² = 0.

  For example, the angular velocity determination unit 230 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero when the state where the angular velocity ω calculated by the angular velocity calculation unit 220 is substantially zero continues for a predetermined time. Also good.

  The offset correction unit 40 is the same as that in the first embodiment, and a description thereof will be omitted.

  As described above, the sensor device 1B according to the present embodiment is obtained sequentially by periodically sampling the axis vectors in the x-axis, y-axis, and z-axis directions in the initial state and the output voltages of the acceleration sensors 10x, 10y, and 10z. The offset of the output of the angular velocity sensors 20x, 20y, and 20z at the timing when the square of the angular velocity ω calculated based on the acceleration component in the x-axis, y-axis, and z-axis directions and the temporal change of the acceleration component becomes zero. (Zero point offset) is automatically corrected.

[Judgment principle of offset correction timing]
Next, the principle of determining timing for performing the offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment will be described.

  In the present embodiment, the attitude of the sensor device 1B is expressed by the Euler angle of the ZXZ system with reference to the state where the absolute coordinate system (XYZ coordinate system) and the sensor coordinate system (xyz coordinate system) match.

As shown in FIG. 6A, a rotation matrix R ₁ for converting an absolute coordinate system (XYZ coordinate system) into an X′Y′Z ′ coordinate system obtained by rotating the absolute coordinate system (XYZ coordinate system) by an angle φ around the Z axis is expressed by the following equation (3): Given in.

Further, as shown in FIG. 6B, a rotation matrix R ₂ for converting the X′Y′Z ′ coordinate system into an X ″ Y ″ Z ″ coordinate system rotated by an angle θ around the X ′ axis. Is given by the following equation (4).

Further, as shown in FIG. 6C, an X ′ ″ Y ′ ″ Z ′ ″ coordinate system obtained by rotating the X ″ Y ″ Z ″ coordinate system by an angle ψ around the Z ″ axis. The rotation matrix R ₃ to be converted into is given by the following equation (5).

  If the X ′ ″ Y ′ ″ Z ′ ″ coordinate system matches the sensor coordinate system (xyz coordinate system), the Euler angle (posture angle) of the ZXZ system that expresses the posture of the sensor device 1B. Is (φ, θ, ψ).

  Therefore, the rotation matrix R for converting the attitude angle of the sensor device 1B from (0, 0, 0) to (φ, θ, ψ) is given by the following equation (6).

  In the present embodiment, when the sensor device 1B is in the reference posture (when the posture angle is (0, 0, 0)), the absolute coordinate system (XYZ coordinate system) and the sensor coordinate system (xyz coordinate system) match. , X-axis, y-axis, and z-axis directions are represented by (1,0,0), (0,1,0), (0,0,1) in the absolute coordinate system (XYZ coordinate system), respectively. It is represented by

In the present embodiment, since the detection axes of the acceleration sensors 10x, 10y, and 10z always coincide with the x-axis, y-axis, and z-axis of the sensor coordinate system, respectively, when the sensor device 1B is in the reference posture (the posture angle is (0, 0,0)), the unit vectors a _x , a _y , and a _{z in} the detection axis direction of the acceleration sensors 10x, 10y, and 10z are a _x = (1, 0, 0) and a _y = (0, 1, 0) and a _z = (0, 0, 1).

Therefore, when the posture angle of the sensor device 1B is (φ, θ, ψ), the unit vectors a _x ^R , a _y ^R , and a _z ^R in the x-axis, y-axis, and z-axis directions are expressed by the following formulas (7 ), Formula (8), and formula (9).

Next, it is assumed that the sensor device 1B is stopped at a posture angle (φ, θ, ψ) or is linearly moving at a constant speed, and from this state, the sensor device 1B has an arbitrary axis vector n = (n _x , n _y , Considering the case of rotating around an angle δ around n _z ), a rotation matrix Δ representing this rotation is expressed by the following equation (10).

Thus, axial vector _{n = (n x, n y} , n z) x -axis after the rotation by an angle δ around the, y-axis, z-axis direction of the unit vector ^{_{a x RΔ, a y RΔ,}} a z RΔ is Are represented by the following equations (11), (12), and (13), respectively.

Therefore, the angles γ _x , γ _y , and γ _z formed by the unit vectors a _x ^RΔ , a _y ^RΔ , and a _z ^RΔ with the unit vector p = (0, 0, 1) in the direction of gravity are respectively expressed by the following formulas ( 14), equation (15), and equation (16).

Here, when the centrifugal acceleration R shown in FIG. 2B is extremely small, the acceleration components g _x , g _y , and g _z detected by the acceleration sensors 10x, 10y, and 10z are the x-axis of the gravitational acceleration G, y This coincides with the components in the axial and z-axis directions. That is, since g _x = G · cos γ _x , g _y = G · cos γ _y , and g _z = G · cos γ _z , the following formula (17) is obtained from formula (14), formula (15), and formula (16), respectively. Equation (18) and Equation (19) are derived. Note that D ₁ , D ₂ , and D ₃ in Expression (17), Expression (18), and Expression (19) are given by Expression (20), Expression (21), and Expression (22), respectively.

  When the equations (17), (18), and (19) are put together, the following equation (23) is obtained.

When Kramel's formula is applied to this equation (23), D ₁ , D ₂ , and D ₃ are obtained by the following equations (24), (25), and (26), respectively.

Since D ₁ , D ₂ , and D ₃ are given by Expression (20), Expression (21), and Expression (22), respectively, the first derivatives of D ₁ , D ₂ , and D ₃ are respectively expressed by the following expressions (27) , (28) and (29).

The second derivatives of D ₁ , D ₂ , and D ₃ are obtained by further differentiating the expressions (27), (28), and (29), and the following expressions (30), (31), and (32), respectively. ).

  Here, a relational expression of the following expression (33) is obtained from the expressions (20), (21), and (22).

  Further, a relational expression of the following expression (34) is obtained from the expressions (27), (28), and (29).

  Further, the relational expression of the following expression (35) is obtained from the expressions (30), (31), and (32).

  When the equations (33), (34), and (35) are put together, the following equation (36) is obtained.

Applying Cramer formula for this equation _{(36), n x, n} y, n z is each of the following equation (37), equation (38), obtained by the equation (39).

  Finally, by eliminating δ from the equations (27) and (28), the square of the angular velocity ω applied to the sensor device 1B is obtained by the following equation (40).

Here, if the sensor device 1B is stopped in the initial state or is in a linear motion at a constant speed (if it is not rotating), no angular velocity is applied to the sensor device 1B, so the angular velocity sensors 20x, 20y, 20z All output zero-point voltage. At this time, the time changes of g _x , g _y , and g _z are 0, and D1, D2, and D3 are constant values. Therefore, the values obtained by first-order differentiation of D1, D2, and D3 are all 0. Therefore, ω ² calculated by the equation (40) becomes zero.

On the other hand, the sensor apparatus 1B any axis _{n = (n x, n y} , n z) if the rotational motion around, the sensor device 1B joined by an angular velocity of this rotational movement, the angular velocity sensor 20x, 20y, 20z detects the x-axis component, y-axis component, and z-axis component of this angular velocity. At this time, since g _x , g _y , and g _z change with time, ω ² calculated by Expression (40) does not become zero.

Therefore, the angular velocity determination unit 230, an angular velocity applied to the sensor apparatus 1B determines whether 0 or not depending on whether omega ² which is calculated by the equation (40) becomes zero, the angular velocity sensor 20x, 20y, offset 20z Controls the timing of the correction process. However, actually, even if the sensor device 1B stops or moves at a constant speed due to environmental factors such as an output offset of the acceleration sensors 10x, 10y, and 10z and noise in the environment where the sensor device 1B is used, the acceleration sensors 10x and 10y It is assumed that the acceleration g detected by 10z does not slightly match the gravitational acceleration G. Therefore, the angular velocity determination unit 230 determines that the angular velocity applied to the sensor device 1B is 0, for example, if ω ² calculated by the equation (40) is less than or equal to a small value Δ, that is, satisfies ω ² ≦ Δ. You may make it do. The minute value Δ is set to an appropriate value according to the specification on the application side using the sensor device 1B.

[Offset correction processing]
FIG. 7 is a flowchart showing a first example of offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment.

First, the initial state detection unit 210 samples detection signals from the acceleration sensors 10x, 10y, and 10z, and calculates acceleration components g _x , g _y , and g _z in the x-axis, y-axis, and z-axis directions (step S110).

Next, the initial state detection unit 210 calculates g ² = g _x ² + g _y ² + g _z ² (step S120).

Next, the initial state detection unit 210 determines whether g _x ² + g _y ² + g _z ² and G ² match (step S130). If g ² ≠ G ² (the initial state is not detected), (N of step S130), the process of step S110 and S120 is performed again.

On the other hand, when g ² = G ² (Y in step S130), the initial state detection unit 210 detects the initial state (step S140), and the angular velocity calculation unit 220 detects the equations (7), (8), and According to (9), from the posture angle (φ, θ, ψ) calculated by the posture information calculation unit 70, the x-axis direction, y-axis direction, and axial direction unit vector a _x of the acceleration sensors 10x, 10y, and 10z in the initial state. ^{R 1} , a _y ^R and a _z ^R are calculated (step S150).

Next, the angular velocity calculation unit 220 calculates the equation (24) from the unit vectors a _x ^R , a _y ^R , a _z ^R obtained in step S150 and the acceleration components g _x , g _y , g _z obtained in step S110. ), formula (25), the equation _(26), calculates the _{D 1, D 2, D 3} ( step S160).

Next, the angular velocity calculation unit 220 calculates first-order derivatives of D ₁ , D ₂ , and D ₃ (Step S170). Specifically, the angular velocity calculation unit 220 calculates the current D ₁ , D ₂ , D ₃ and the previous D ₁ , D ₂ , D ₃ (g _x , g _y , g _z one sample before) calculated in step S160. Each difference (D ₁ , D ₂ , D ₃ first-order difference) with D ₁ , D ₂ , D ₃ ) calculated from ( ₁ ) is calculated.

Next, the angular velocity calculation unit 220 calculates the second derivative of D ₁ , D ₂ , and D ₃ using Equation (30), Equation (31), and Equation (32) (Step S180). Specifically, the angular velocity calculation unit 220 calculates the first-order difference between the current D ₁ , D ₂ , and D ₃ calculated in step S170 and the previous first-order difference between D ₁ , D ₂ , and D ₃ (one sample before) Each difference ( _second difference of D ₁ , D ₂ , D ₃ ) with D ₁ , D ₂ , D ₃ calculated from g _x , g _y , g _z is calculated.

Next, the angular velocity calculation unit 220 calculates ω ^{2 according} to the equation (40) (step S190).

Next, the angular velocity determination unit 230 determines whether or not ω ² = 0 (step S200). If ω ² ≠ 0 (N in step S200), the processes in steps S110 to S190 are performed again.

On the other hand, when ω ² = 0 (Y in step S200), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S210).

  FIG. 8 is a flowchart showing a second example of offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment. 8, steps that perform the same processing as in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  First, the initial state detection unit 210 performs steps S110 to S140.

  First, the angular velocity determination unit 230 starts measuring the predetermined time T2 (step S142).

Next, after the angular velocity calculation unit 220 performs the processing of steps S150 to S190, the angular velocity determination unit 230 determines whether or not ω ² = 0 (step S200). If ω ² ≠ 0 (step S200) N), the initial state detection unit 210 performs the initial state detection processing (steps S110 to S140) again.

On the other hand, when ω ² = 0 (Y in step S200), the angular velocity determination unit 230 determines whether or not a predetermined time T2 has elapsed since the measurement was started in step S142 (step S202), and the predetermined time When T2 has not elapsed (N in step S202), the initial state detection unit 210 samples the detection signals of the acceleration sensors 10x, 10y, and 10z, and the acceleration components g _x , _x- axis, z-axis directions, g _y and g _z are calculated (step S204), and the processes of steps S150 to S200 are repeated until the predetermined time T2 elapses. However, if ω ² ≠ 0 in the determination process of step S200 before the predetermined time T2 has elapsed, the initial state detection unit 210 performs the initial state detection process (the processes of steps S110 to S140) again.

  When the predetermined time T2 has elapsed (Y in step S202), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S210).

  In this way, it is distinguished whether the angular velocity is continuously applied to the sensor device 1B for a predetermined time T2 or more, or whether the angular velocity is instantaneously zero, and only in the former case, the angular velocity sensors 20x, 20y, 20z are distinguished. The offset correction can be performed.

  According to the sensor device of the second embodiment described above, the same effects as the sensor device of the first embodiment can be obtained. Furthermore, according to the sensor device of the second embodiment, even when a small centrifugal force that cannot be detected by the acceleration sensor is applied, the angular velocity applied to the angular velocity sensor can be reduced by monitoring the temporal change of the acceleration component from the initial state. Can be detected. Therefore, the determination accuracy of the timing for performing the offset correction of the angular velocity sensor can be improved.

(3) Third Embodiment [Configuration]
FIG. 9 is a schematic configuration diagram of the sensor device of the third embodiment. 9, the same components as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  As illustrated in FIG. 9, the sensor device 1 </ b> C of the third embodiment includes a determination unit 80 instead of the determination unit 40 of FIG. 5.

  In this embodiment, the determination unit 80 includes the same initial state detection unit 210 and angular velocity calculation unit 220 as those in FIG.

  In the present embodiment, the determination unit 80 includes a determination mode control unit 240. The determination mode control unit 240 switches between the first determination mode and the second determination mode according to the control signal. This control signal may be supplied from the outside of the sensor device 1C, or may be generated inside the sensor device 1C.

In the present embodiment, the determination unit 80 includes an angular velocity determination unit 250. In the first determination mode, the angular velocity determination unit 250 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero when the initial state detection unit 210 detects the initial state. In the present embodiment, in the first determination mode, the angular velocity determination unit 250 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is 0 if g _x ² + g _y ² + g _z ² = G ^2. To do.

Further, in the second determination mode, the angular velocity determination unit 250 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero when the angular velocity calculated by the angular velocity calculation unit 220 is approximately zero. In the present embodiment, the angular velocity determination unit 250 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is zero in the second determination mode if ω ² = 0.

  For example, in the first determination mode, the angular velocity determination unit 250 determines that the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z is 0 when the initial state detection unit 210 detects the initial state for a predetermined time. You may make it do. In addition, for example, in the second determination mode, the angular velocity determination unit 250 determines the angular velocity applied to the angular velocity sensors 20x, 20y, and 20z when the angular velocity ω calculated by the angular velocity calculation unit 220 is substantially zero for a predetermined time. You may make it determine with it being 0.

As described above, in the first determination mode, the sensor device 1C according to the present embodiment periodically sums the squares of accelerations (g _x ² + g) obtained by periodically sampling the output voltages of the acceleration sensors 10x, 10y, and 10z. The offset (zero point offset) of the outputs of the angular velocity sensors 20x, 20y, and 20z is automatically corrected at the timing when _y ² + g _z ² ) and the square of gravity acceleration (G ² ) coincide. In the second determination mode, the sensor device 1C according to the present embodiment periodically samples the axis vectors in the x-axis, y-axis, and z-axis directions in the initial state and the output voltages of the acceleration sensors 10x, 10y, and 10z. The angular velocity sensors 20x, 20y, 20x, 20y, and the angular velocity sensors 20x, 20y, The offset of the output of 20z (zero point offset) is automatically corrected.

[Offset correction processing]
FIG. 10 is a flowchart illustrating a first example of offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment. 10, steps that perform the same processing as in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  First, the initial state detection unit 210 performs initial state detection processing (steps S110 to S140).

  Next, if it is 1st determination mode (Y of step S144), the offset correction part 40 will perform offset correction of the angular velocity sensors 20x, 20y, and 20z (step S210).

If it is not the first determination mode (that is, if it is the second determination mode) (N in step S144), after the angular velocity calculation unit 220 performs the processing of steps S150 to S190, the angular velocity determination unit 250 sets ω ² =. It is determined whether or not 0 (step S200). If ω ² ≠ 0 (N in step S200), the initial state detection unit 210 performs the initial state detection process (steps S110 to S140) again.

On the other hand, when ω ² = 0 (Y in step S200), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S210).

  FIG. 11 is a flowchart showing a second example of offset correction processing of the angular velocity sensors 20x, 20y, and 20z in the present embodiment. 11, steps that perform the same processing as in FIG. 10 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  First, if it is the 1st determination mode (Y of Step S102), angular velocity judgment part 250 will start measurement of predetermined time T1 (Step S104).

  Next, the initial state detection unit 210 performs initial state detection processing (steps S110 to S140).

  Next, if it is the first determination mode (Y in step S144), the angular velocity determination unit 250 determines whether or not a predetermined time T1 has elapsed since the start of measurement in step S104 (step S145). If the predetermined time T1 has not elapsed (N in step S145), the initial state detection unit 210 performs the processes in steps S110 to S140 again until the predetermined time T1 has elapsed. When the predetermined time T1 has elapsed (Y in step S145), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S210).

  If it is not the first determination mode (that is, if it is the second determination mode) (N in Step S144), the angular velocity determination unit 250 starts measuring the predetermined time T2 (Step S148).

Next, after the angular velocity calculation unit 220 performs steps S150 to S190, the angular velocity determination unit 250 determines whether ω ² = 0 (step S200). If ω ² ≠ 0 (step S200) N), the initial state detection unit 210 performs the initial state detection processing (steps S110 to S140) again.

On the other hand, if ω ² = 0 (Y in step S200), the angular velocity determination unit 250 determines whether or not a predetermined time T2 has elapsed since the measurement was started in step S148 (step S202), and the predetermined time When T2 has not elapsed (N in step S202), the initial state detection unit 210 samples the detection signals of the acceleration sensors 10x, 10y, and 10z, and the acceleration components g _x , _x- axis, z-axis directions, g _y and g _z are calculated (step S204), and the processes of steps S150 to S200 are repeated until the predetermined time T2 elapses. However, if ω ² ≠ 0 in the determination process of step S200 before the predetermined time T2 has elapsed, the initial state detection unit 210 performs the initial state detection process (the processes of steps S110 to S140) again.

  When the predetermined time T2 has elapsed (Y in step S202), the offset correction unit 40 performs offset correction of the angular velocity sensors 20x, 20y, and 20z (step S210).

  In this way, in the first determination mode, it is distinguished whether the centrifugal force is continuously applied to the sensor device 1C for a predetermined time T1 or more, or whether the centrifugal force is instantaneously zero. The offset correction of the angular velocity sensors 20x, 20y, and 20z can be performed only in the case. Further, in the second determination mode, it is distinguished whether the angular velocity is continuously applied to the sensor device 1C for a predetermined time T2 or whether the angular velocity is instantaneously zero, and only in the former case, the angular velocity sensor 20x, It is possible to perform offset correction of 20y and 20z.

  According to the sensor device of the third embodiment described above, the same effect as that of the sensor device of the first embodiment can be obtained. Furthermore, according to the sensor device of the third embodiment, the offset correction timing of the angular velocity sensor is determined depending on which one of the first determination mode and the second determination mode is used according to the application using the sensor device. The determination accuracy can be changed. That is, if the first determination mode is set, the determination is simple based on the detection of the centrifugal force. If the second determination mode is set, the sensor device even when a minute centrifugal force that cannot be detected by the acceleration sensor is applied. It can be determined whether or not the angular velocity applied to is zero.

2. Electronic Device FIG. 12 is a functional block diagram illustrating a configuration example of an electronic device including the sensor device of the present embodiment. The electronic device 500 of the present embodiment includes a sensor device 400, a host CPU 300, an operation unit 310, a display unit 320, a ROM (Read Only Memory) 330, a RAM (Random Access Memory) 340, and a communication unit 350. .

  A host CPU (microcomputer) 300 performs various types of calculation processing and control processing in accordance with programs stored in the ROM 330. Specifically, the host CPU 300 transmits various control commands to the sensor device 400 to control the operation of the sensor device 400, or receives data from the sensor device 400 and performs various calculation processes. In addition, the host CPU 300 performs various processes in accordance with operation signals from the operation unit 310, processes for transmitting display signals for displaying various types of information on the display unit 320, and a communication unit 350 for performing data communication with the outside. The process etc. which control are performed.

  The operation unit 310 is an input device including operation keys, button switches, and the like, and outputs an operation signal corresponding to an operation by a user to the host CPU 300.

  The display unit 320 is a display device configured by an LCD (Liquid Crystal Display) or the like, and displays various types of information (for example, navigation information) based on a display signal input from the host CPU 300.

  The ROM 330 stores programs for the host CPU 300 to perform various calculation processes and control processes, various application programs, data, and the like (for example, programs and data for performing navigation and attitude control).

  The RAM 340 is used as a work area of the host CPU 300, and temporarily stores programs and data read from the ROM 330, data input from the operation unit 310, calculation results executed by the host CPU 300 according to various programs, and the like.

  The communication unit 350 performs various controls for establishing data communication between the CPU 300 and an external device.

  The sensor device 400 is, for example, the sensor devices 1A, 1B, 1C or the like of the first to third embodiments described above, and the x-axis, y-axis, and z-axis of the sensor are in the electronic device 500 inside the electronic device 500. Are fixed and arranged so as to face in a predetermined direction. Then, the sensor device 400 determines whether or not the angular velocity applied to the sensor device 400 (electronic device 500) is zero, and corrects the offset of the zero point voltage of the angular velocity sensor when the angular velocity is zero. By incorporating this sensor device 400 into the electronic device 500, the offset of the angular velocity sensor of the sensor device can be automatically corrected regardless of the application.

  Examples of the electronic device 500 include various electronic devices such as a game controller and an input device such as a three-dimensional mouse, a toy such as a radio controlled helicopter, a robot, a navigation device (navigation device), a mobile phone, and a mobile personal computer.

  In addition, this invention is not limited to this embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  For example, the sensor device according to the present embodiment includes three angular velocity sensors, but may include one or more angular velocity sensors.

  Further, for example, the sensor device of the present embodiment includes three acceleration sensors, but includes three or more acceleration sensors, and three axes orthogonal to each other based on part or all of the outputs of the acceleration sensors. You may deform | transform so that the acceleration of a direction may be calculated. Further, the three acceleration sensors are not necessarily arranged so that the three detection axes are orthogonal to each other, and may be arranged so that the three axes are not parallel to each other. When the three axes are not orthogonal to each other, the processing described in the present embodiment may be performed after the angular velocity in the three-axis direction is converted into the angular velocity in the orthogonal coordinate system by alignment correction.

  In the sensor device of the present embodiment, the angular velocity sensors 20x, 20y, and 20z have a zero point voltage adjustment function, and the offset correction unit 40 supplies a zero point adjustment signal to the angular velocity sensors 20x, 20y, and 20z. Although the offset correction processing is realized, the present invention is not limited to this. For example, when the angular velocity sensors 20x, 20y, and 20z do not have a zero point voltage adjustment function, the offset correction unit 40 is based on the output voltage of the angular velocity sensors 20x, 20y, and 20z at the timing of the offset correction processing and the specifications. A correction voltage corresponding to an error from the zero point voltage is generated, and the correction voltage and the output voltages of the angular velocity sensors 20x, 20y, and 20z are added to each other, so that these output voltages are converted into the zero point voltage in the specification. You may make it match.

The sensor devices of the second and third embodiments are configured as posture sensors including the posture information calculation unit 70, and the angular velocity calculation unit 220 sets the posture angle calculated by the posture information calculation unit 70 in the initial state. angle (φ, θ, ψ) is performed the ω ² of the calculation as, but not limited to this. If the sensor device is not the posture sensor, the posture information calculation unit 70 is not included, and the angular velocity calculation unit 220 receives the posture angle (φ, θ, ψ) in the initial state from the outside of the sensor device, and calculates ω ^2. You may do it. Further, the geomagnetic sensors 60x, 60y, and 60z are not essential components and may be omitted.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

1A, 1B, 1C sensor device, 10x, 10y, 10z acceleration sensor, 20x, 20y, 20z angular velocity sensor, 30 determination unit, 40 offset correction unit, 50 determination unit, 60x, 60y, 60z geomagnetic sensor, 70 attitude information calculation unit 110 acceleration calculation unit, 120 angular velocity determination unit, 210 initial state detection unit, 220 angular velocity calculation unit, 230 angular velocity determination unit, 240 determination mode control unit, 250 angular velocity determination unit, 300 host CPU, 310 operation unit, 320 display unit, 330 ROM, 340 RAM, 350 communication unit, 400 sensor device, 500 electronic device

Claims (6)

A sensor device including an angular velocity sensor and three or more acceleration sensors,
A determination unit that determines whether or not an angular velocity applied to the angular velocity sensor is 0 based on an output of the acceleration sensor;
An offset correction unit that corrects an offset of an output of the angular velocity sensor when the angular velocity is determined to be 0 by the determination unit;
The determination unit
An initial state detection unit that calculates an acceleration applied to the sensor device based on an output of the acceleration sensor, and detects a state in which the calculated acceleration and gravity acceleration substantially coincide with each other as an initial state;
An axis vector in each detection axis direction in the initial state is calculated based on posture information of the sensor device in the initial state, and based on the axis vector, an acceleration component in each detection axis direction, and a change in time of the acceleration component. An angular velocity calculator that calculates an angular velocity at which the sensor device rotates about an arbitrary axis;
An angular velocity determination unit that determines that the angular velocity applied to the angular velocity sensor is zero when the angular velocity calculated by the angular velocity calculation unit is approximately zero. In claim 1,
The angular velocity determination unit
A sensor device that determines that an angular velocity applied to the angular velocity sensor is zero when a state in which the angular velocity calculated by the angular velocity calculator is substantially zero continues for a predetermined time. In claim 1,
The determination unit
A determination mode control unit that switches between the first determination mode and the second determination mode according to the control signal;
In the first determination mode, it is determined that the angular velocity applied to the angular velocity sensor is 0 when the initial state detection unit detects the initial state, and in the second determination mode, the angular velocity calculation unit calculates An angular velocity determination unit that determines that the angular velocity applied to the angular velocity sensor is zero when the angular velocity is approximately zero. In claim 3,
The angular velocity determination unit
In the first determination mode, it is determined that the angular velocity applied to the angular velocity sensor is 0 when the initial state detection unit continuously detects the initial state for a predetermined time, and in the second determination mode, the A sensor device that determines that an angular velocity applied to the angular velocity sensor is zero when a state in which the angular velocity calculated by the angular velocity calculator is substantially zero continues for a predetermined time.   An electronic device comprising the sensor device according to claim 1. An angular velocity sensor offset correction method for correcting an offset of an output of the angular velocity sensor in a sensor device including an angular velocity sensor and three or more acceleration sensors,
A determination step of determining whether an angular velocity applied to the angular velocity sensor is zero based on an output of the acceleration sensor;
An offset correction step of correcting an offset of an output of the angular velocity sensor when the angular velocity is determined to be 0 in the determination step,
The determination step includes
An initial state detecting step of calculating an acceleration applied to the sensor device based on an output of the acceleration sensor, and detecting a state in which the calculated acceleration and a gravitational acceleration substantially coincide with each other as an initial state;
An axis vector in each detection axis direction in the initial state is calculated based on posture information of the sensor device in the initial state, and based on the axis vector, an acceleration component in each detection axis direction, and a change in the acceleration component with time An angular velocity calculating step of calculating an angular velocity at which the sensor device rotates around an arbitrary axis;
An angular velocity sensor offset correction method comprising: an angular velocity determination step of determining that an angular velocity applied to the angular velocity sensor is zero when the angular velocity calculated in the angular velocity calculation step is substantially zero.

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