Inertial sensor

Abstract

To provide an inertial sensor that can avoid deteriorating detection accuracy involved in correlation between physical quantities.SOLUTION: An inertial sensor 1 includes a first sensor S1, a first detection circuit C1, a second sensor S2, a second detection circuit C2, and a range setting unit 140. The first sensor S1 detects a first physical quantity PQ1 on a first axis A1. The first detection circuit C1 performs detection processing of the first physical quantity PQ1 based on a first sensor signal SG1 from the first sensor S1 and outputs first detection information DI1. The second sensor S2 detects a second physical quantity PQ2 on a second axis A2. The second detection circuit C2 performs detection processing of the second physical quantity PQ2 based on a second sensor signal SG2 from the second sensor S2 and outputs second detection information DI2. The range setting unit 140 performs range setting processing of setting a detection range of the first physical quantity PQ1 in the first detection circuit C1 based on the first detection information DI1 and the second detection information DI2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inertial sensor or the like.

Background Art

[0002] Patent Document 1 discloses a method for changing the detection range of an inertial sensor. According to this method, the detection circuit of the inertial sensor changes the detection range by changing the voltage value per unit physical quantity based on the output signal that has passed through the filter section.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the method disclosed in Patent Document 1, the setting of the detection range of a certain physical quantity is performed based only on that physical quantity. Therefore, the detection accuracy of the inertial sensor depends on the detection accuracy of the inertial sensor itself, and it may be difficult to detect a physical quantity with high accuracy using the inertial sensor. Also, since the detection range of the physical quantity is set based only on a specific physical quantity in the inertial sensor, there is a possibility of causing a problem that the inertial sensor lags behind when the physical quantity fluctuates.

Means for Solving the Problems

[0005] One aspect of the present disclosure includes a first sensor for detecting a first physical quantity in a first axis; a first detection circuit that performs detection processing of the first physical quantity based on a first sensor signal from the first sensor and outputs first detection information; a second sensor for detecting a second physical quantity in a second axis; a second detection circuit that performs detection processing of the second physical quantity based on a second sensor signal from the second sensor and outputs second detection information; and a range setting unit that performs range setting processing, wherein the range setting unit relates to the inertial sensor that performs range setting processing to set the detection range of the first physical quantity in the first detection circuit based on the first detection information and the second detection information. [Brief explanation of the drawing]

[0006] [Figure 1] An example configuration of the inertial sensor of this embodiment. [Figure 2] A diagram showing the relationship between output voltage and dynamic range. [Figure 3] A circuit diagram showing an example of a range adjustment section. [Figure 4] A diagram showing details of an example configuration of the inertial sensor in this embodiment. [Figure 5] A specific example of the configuration of the inertial sensor of this embodiment. [Figure 6] A diagram explaining Euler angles. [Figure 7] A diagram illustrating tangential acceleration. [Figure 8] A diagram illustrating centripetal acceleration. [Figure 9] An example of range adjustment when applying the third embodiment. [Figure 10] A diagram showing an example of the time evolution of angular velocity. [Figure 11] A diagram showing an example of how acceleration changes over time. [Figure 12] An example of range adjustment when applying the fourth embodiment. [Figure 13] An example of range adjustment when applying the fifth embodiment. [Modes for carrying out the invention]

[0007] The following describes this embodiment. Note that the embodiment described below does not unduly limit the scope of the claims. Furthermore, not all of the configurations described in this embodiment are necessarily essential components.

[0008] 1. Inertial sensor The inertial sensor 1 of this embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing an example of the configuration of the inertial sensor 1. The inertial sensor 1 can be realized as, for example, a MEMS (Micro Electro Mechanical Systems) device. Note that, for the sake of explanation, not all components are shown in Figure 1 and Figures 4 and 8 described later. For example, electrode wiring, electrode terminals, etc., are omitted from the illustration as appropriate. Furthermore, the following description will use the case where the physical quantities detected by the inertial sensor 1 are acceleration, angular velocity, and attitude as an example, but the physical quantities are not limited to these and may be other physical quantities such as displacement, velocity, and the rate of change of angular velocity over time. Next, we will consider the motion of the device on which the inertial sensor 1 is mounted in three-dimensional space. Three-dimensional space is understood using the first axis A1, second axis A2, and third axis A3, which are perpendicular to each other. The first axis A1, second axis A2, and third axis A3 are, for example, the X axis, Y axis, and Z axis. The X axis and Y axis are axes parallel to the mounting surface on which the inertial sensor 1 is installed. Furthermore, the Z-axis is the axis perpendicular to the mounting surface on which the inertial sensor 1 is installed, i.e., the XY plane. Note that "perpendicular" includes not only intersections at 90°, but also intersections at angles slightly tilted from 90°.

[0009] Inertial sensor 1 detects physical quantities. Inertial sensor 1 is an element that detects physical quantities such as velocity, displacement, and angular velocity, and is implemented by, for example, a MEMS (Micro Electro Mechanical Systems) device.

[0010] The inertial sensor 1 of this embodiment detects physical quantities as a first physical quantity PQ1 and a second physical quantity PQ2. The first physical quantity PQ1 is, for example, acceleration, angular velocity, or attitude. Acceleration is the acceleration along each of the first axis A1, second axis A2, and third axis A3, and angular velocity is the angular velocity along each of the first axis A1, second axis A2, and third axis A3. Attitude is a physical parameter that identifies the attitude, as explained in Figure 6 below, and is a physical quantity expressed by, for example, an Euler angle or a quaternion. The second physical quantity PQ2 is a physical quantity other than the first physical quantity PQ1 among the above physical quantities. Furthermore, as will be described later in "2. Second Embodiment", the inertial sensor 1 also detects physical quantities as a third physical quantity PQ3. The third physical quantity PQ3 is a physical quantity other than the first physical quantity PQ1 and the second physical quantity PQ2 among the above physical quantities.

[0011] As shown in Figure 1, the inertial sensor 1 of this embodiment includes a first sensor 51, a second sensor 52, a first detection circuit 61, a second detection circuit 62, a range setting unit 140, and an attitude calculation unit 150.

[0012] The first sensor S1 and the second sensor 2 are sensors that detect physical quantities, respectively. Specifically, they detect acceleration or angular velocity. Acceleration is detected for the acceleration of the first axis A1, second axis A2, and third axis A3 using, for example, a capacitive accelerometer, a frequency-variable accelerometer, or a piezoresistive accelerometer. Angular velocity is detected for the angular velocity with the first axis A1, second axis A2, and third axis A3 as the axes of rotation using, for example, a capacitive angular velocity sensor, a frequency-variable angular velocity sensor, or an optical fiber gyroscope.

[0013] Based on the first sensor signal SS1, which is the detection information of the first sensor 51, the first detection circuit 61 performs processes such as amplification, range adjustment, filter processing, or A / D conversion of the signal, and after the processing, outputs it as the first detection information DI1. Based on the first sensor signal SS2, which is the detection information of the second sensor S2, the second detection circuit C2 performs the same processes as the first sensor 51 and outputs it as the second detection information DI2. Regarding the first physical quantity PQ1, the detection information output from the first detection circuit C1 is referred to as the first detection information DI1. Similarly, the second detection information DI2 refers to the detection information output from the second detection circuit C2 regarding the second physical quantity PQ2.

[0014] The first range adjustment unit 81 of the first detection circuit 61 is responsible for range adjustment in the first detection circuit 61. Specifically, the first range adjustment unit 81 changes the dynamic range. The dynamic range is the ratio of the minimum value to the maximum value of distinguishable signals and is one of the analog indicators representing the information amount of the signal. Similarly, the second range adjustment unit 82 of the second detection circuit 62 is also responsible for range adjustment in the second detection circuit 62. Range adjustment means adjusting the detection range of the physical quantity detected by the first sensor circuit or the second sensor circuit. That is, the first range adjustment unit 81 and the second range adjustment unit 82 perform range adjustment so as to be the optimal ranges determined by the range setting unit 140, respectively. In the following description, the first range adjustment unit 81 and the second range adjustment unit 82 are collectively referred to as the range adjustment unit.

[0015] FIG. 2 is a diagram for explaining the dynamic range. As shown in FIG. 2, with a constant output voltage width, when the slope of the output voltage with respect to the physical quantity is increased suddenly, the dynamic range of the physical quantity becomes narrow, and conversely, when the slope of the output voltage is made gentle, the dynamic range of the physical quantity becomes wide. Here, the output voltage width corresponds to the output range of the physical quantity, and the slope of the output voltage corresponds to the detection sensitivity. Therefore, with a constant output range, when the sensitivity is increased suddenly, the dynamic range of the physical quantity becomes wide, and conversely, when the sensitivity is made gentle, the dynamic range of the physical quantity becomes narrow. In other words, by changing the voltage value per unit physical quantity, the dynamic range is changed. In the following, the dynamic range will be described as the detection range as appropriate. Also, the adjustment of the dynamic range will be simply described as range adjustment.

[0016] An example of the range adjustment unit is shown in FIG. 3. In FIG. 3, the range adjustment unit operates as a variable gain amplifier (not shown) and also operates as a high-pass filter. Also, the operational amplifier is shared by the high-pass filter, which is an active filter, and the variable gain amplifier.

[0017] The non-inverting amplification type range adjustment unit shown in FIG. 3 includes an operational amplifier OPD1. It also includes a capacitor CD1 provided between an input node ND1 and a node ND2, and a resistor RD1 provided between the node ND2 and a node of the reference power supply voltage AGND. The reference power supply voltage AGND is, for example, the first power supply voltage.

[0018] The range adjustment unit also includes variable resistors RD2 and RD3 provided between an output node ND3 and a node of AGND. Also, the node ND2 is connected to the non-inverting input terminal of the operational amplifier OPD1, and the output tap QT of the variable resistors RD2 and RD3 is connected to the inverting input terminal of the operational amplifier OPD1. Here, the output tap QT is provided at a node ND4. Then, the output node ND3 is connected to the output terminal of the operational amplifier OPD1.

[0019] In Figure 3, the resistance value of the variable resistor RD3 between output node ND3 and node ND4 where output tap QT is located, and the resistance value of the variable resistor RD2 between node ND4 and the AGND node are variably controlled based on the sensitivity adjustment data DPGA[m:0]. This adjusts the gain of the range adjustment section (not shown), thereby adjusting the dynamic range through sensitivity adjustment. For example, if the resistance values ​​of variable resistors RD2 and RD3 are R2 and R3, the gain of the range adjustment section, which is PGA, becomes G=(R2+R3) / R2. Specifically, multiple output taps are provided for the variable resistors, and by selecting the output tap QT corresponding to the adjustment data DPGA[m:0] from among these multiple output taps, the resistance values ​​R2 and R3 of variable resistors RD2 and RD3 are determined, and the gain G=(R2+R3) / R2 is determined.

[0020] The range setting unit 140 determines whether or not to perform range adjustment. Specifically, it determines whether to set the detection range of the physical quantities in the first sensor 51 and the second sensor 52 to the optimal range, and outputs the determination result. Here, this determination is made based on the first detection information DI1 and the second detection information DI2. The determination process performed by the range setting unit 140 is called the range setting process.

[0021] The attitude calculation unit 150 outputs attitude information through calculations. Attitude is represented, for example, by Euler angles or quaternions. The attitude calculation unit 150 receives first detection information DI1 from the first detection circuit 61 and second detection information DI2 from the second detection circuit 62, and generates attitude information DIP, which is attitude information such as Euler angles, based on this information, and outputs it from the inertial sensor 1. The generation of attitude information DIP can be calculated using angular velocity, for example, based on equation (10) described later. In addition, attitude information can also be generated by combining attitude information that can be calculated from acceleration using an attitude calculation filter that applies complementary filters or Kalman filters. The attitude calculation unit 150 also outputs attitude information DIP to the range setting unit 140.

[0022] Figure 4 shows a detailed configuration example of the inertial sensor 1 of this embodiment. Figure 4 shows specific configuration examples of the first detection circuit 61 and the second detection circuit 62. The configuration and operation of the first signal conversion / amplification unit 71, the first analog filter 111, the first A / D conversion circuit 121 and the first digital filter 131, and the first drive circuit 41 of the first detection circuit 61 will be described below. The configuration and operation of the second signal conversion / amplification unit 72, the second analog filter 112, the second A / D conversion circuit 122 and the second digital filter 132, and the first drive circuit 42 of the second detection circuit 62 are similar, so a detailed explanation will be omitted.

[0023] The first signal conversion / amplification unit 71 receives the first sensor signal SS1 from the first sensor 51 and performs signal conversion and amplification processing on the signal. Taking an angular velocity sensor as an example, the amplification process is differential amplification of the differential sensor signal from the angular velocity sensor. The signal conversion process is the process of converting the charge signal from the angular velocity sensor into a voltage signal, and the process of extracting the desired angular velocity signal by synchronous detection based on the synchronous detection signal from the drive circuit. Taking an acceleration sensor as an example, the amplification process is differential amplification of the differential signals from the two fixed electrodes. The signal conversion process is the process of converting the capacitance signal from the acceleration sensor into an acceleration signal.

[0024] The first analog filter 111 performs filtering on the signal after range adjustment. Specifically, it performs low-pass filtering to remove high-frequency components. The first analog filter 111 is used as a pre-filter for the first A / D conversion circuit 121. The first analog filter 111 is a passive filter composed of, for example, resistors and capacitors.

[0025] The first A / D conversion circuit 121 performs A / D conversion on the analog signal from the first analog filter 111 and outputs detection information for the digital signal. For example, the first A / D conversion circuit 121 outputs the first detection information DI1, which is the first digital signal. The second A / D conversion circuit 122 outputs the second detection information DI2, which is the second digital signal.

[0026] As described above, the range setting unit 140 is configured such that the range change determination unit 142 of the range setting unit 140 performs range setting processing based on the first detection information DI1, the second detection information DI2, and attitude information. The attitude calculation unit 150 also performs attitude calculation processing based on the first detection information DI1 and the second detection information DI2. Various methods such as successive approximation type and delta-sigma type can be used as the A / D conversion method of the A / D conversion circuit.

[0027] The first digital filter 131 performs digital filtering on the first detection information DI1, which is a digital signal from the first A / D conversion circuit 121. The first digital filter 131 is implemented using various filters, such as filters that extract specific frequency components, such as FIR filters and IIR filters, and filters for noise removal, such as Kalman filters. The first digital filter 131, which is the digital filter 130, then outputs the first sensor output signal SQ1 to the outside of the inertial sensor 1. The first sensor output signal SQ1 is digital data representing the detection result of the sensor.

[0028] The first drive circuit 41 is a circuit that drives the first sensor 51. If the first sensor 51 is an oscillator, the drive circuit outputs a drive signal to vibrate the sensor. If the sensor is an angular velocity sensor, the drive circuit may include an amplification circuit that amplifies the feedback signal from the sensor, a gain control circuit that performs automatic gain control, and an output circuit that outputs the drive signal to the sensor. If the sensor is an accelerometer, the drive circuit may include an output circuit that outputs a drive signal to the movable electrode of the accelerometer. Note that a drive circuit is not necessarily required.

[0029] Figure 5 shows a more detailed configuration example of the inertial sensor 1 of this embodiment. Figure 5 shows a configuration example when the inertial sensor 1 of this embodiment is applied to a 6-axis motion sensor that combines a 3-axis acceleration sensor and a 3-axis angular velocity sensor.

[0030] In the example shown in Figure 5, acceleration sensors for the X, Y, and Z axes are installed, and angular velocity sensors for the X, Y, and Z axes are installed. One of the X, Y, and Z axis acceleration sensors and the X, Y, and Z axis angular velocity sensors corresponds to the first sensor 51 described in Figures 1 and 4, while the other sensors correspond to the second sensor 52 described in Figures 1 and 4.

[0031] The same applies to the signal conversion amplifier section shown in 70A-70F, the range adjustment section shown in 80A-80F, the analog filter shown in 110A-110F, the A / D conversion circuit shown in 120A-120F, and the digital filter section shown in 130A-130F. For example, one of the signal conversion amplifier sections shown in 70A-70F corresponds to the first signal / conversion amplifier section 71 in Figure 4, and the other signal conversion amplifier sections correspond to the second signal / conversion amplifier section 72 in Figure 4.

[0032] As shown in the example configuration in Figure 5, the system includes sensors for detecting a large number of physical quantities, and consequently, a large number of circuits for detecting these physical quantities are also provided. Furthermore, it is possible to arbitrarily designate any of these circuits as the first sensor 51, the second sensor 52, or any other of them.

[0033] Next, the first embodiment of this embodiment will be described with reference to Figure 5. Figure 5 is a circuit block diagram of the inertial sensor 1 of this embodiment. The inertial sensor 1 is assumed to be a 6-axis motion sensor that combines a 3-axis acceleration sensor and a 3-axis angular velocity sensor.

[0034] First, physical quantities such as acceleration are applied to the inertial sensor 1 from an external source. The physical quantity detection sensors include an X-axis acceleration sensor 50A, a Y-axis acceleration sensor 50B, and a Z-axis acceleration sensor 50C, corresponding to the physical quantities of X-axis acceleration Ax, Y-axis acceleration Ay, and Z-axis acceleration Az, respectively. The physical quantity detection sensors also include an X-axis angular velocity sensor 50D, a Y-axis angular velocity sensor 50E, and a Z-axis angular velocity sensor 50F, corresponding to the physical quantities of X-axis angular velocity ωx, Y-axis angular velocity ωy, and Z-axis angular velocity ωz, respectively. Similarly, the signal conversion / amplification section, range adjustment section, analog filter section, A / D conversion circuit, and digital filter section, which will be described later, also include six parts corresponding to the acceleration and angular velocity of each axis.

[0035] Here, one of the following physical quantities can be designated as the first physical quantity PQ1: X-axis acceleration Ax, Y-axis acceleration Ay, Z-axis acceleration Az, X-axis angular velocity ωx, Y-axis angular velocity ωy, or Z-axis angular velocity ωz. Any other physical quantity can be designated as the second physical quantity PQ2. For example, as shown in Figures 1 and 2, the first physical quantity PQ1 can be the X-axis angular velocity ωx, and the second physical quantity PQ2 can be the Z-axis angular velocity ωz. Here, the first physical quantity PQ1 and the second physical quantity PQ2 may be selected from the attitude information output by the attitude calculation unit 150. Attitude information refers to physical parameters related to attitude, such as Euler angles or quaternions.

[0036] Figure 6 illustrates Euler angles. As shown in Figure 6, Euler angles determine the orientation of an object using three rotation angles: roll angle φ, pitch angle θ, and yaw angle ψ. For example, if the X, Y, and Z axes are perpendicular to each other as shown in Figure 6, the rotation angles around each axis correspond to the roll angle φ, pitch angle θ, and yaw angle ψ. Assuming a car with its center of gravity at the origin O, as shown in Figure 6, if the direction of travel of the car is the X-axis, then the rotation angle around the X-axis, which is aligned with the direction of travel, is the roll angle φ, and the rotation angle around the Y-axis, which is perpendicular to the direction of travel, is the pitch angle θ. The roll angle φ and pitch angle θ fluctuate mainly due to factors such as unevenness and slope of the road surface. The rotation angle around the Z-axis, which is perpendicular to the plane on which the car travels, is the yaw angle ψ. The yaw angle ψ fluctuates mainly due to factors such as the car turning right or left. In other words, the first physical quantity PQ1 or the second physical quantity PQ2 can be selected from the attitude information of the roll angle φ, pitch angle θ, or yaw angle ψ.

[0037] Furthermore, among the elements included in the physical quantity detection sensor, the detection element corresponding to the first physical quantity PQ1 is the first sensor S1. Similarly, the detection element corresponding to the second physical quantity PQ2 is the second sensor S2. In the following, the X-axis acceleration Ax, Y-axis acceleration Ay, and Z-axis acceleration Az will be collectively referred to as acceleration A, and the X-axis angular velocity ωx, Y-axis angular velocity ωy, and Z-axis angular velocity ωz will be collectively referred to as angular velocity ω.

[0038] The sensor signal from the X-axis acceleration sensor 50A is then input to the detection circuit 60A. Here, the detection circuit 60A receives the sensor signal from the X-axis acceleration signal conversion / amplification unit 70A. In this case, the detection circuit 60A corresponds to the first detection circuit 61, and the sensor signal from the X-axis acceleration sensor 50A corresponds to the first sensor signal SS1. In this case, the first detection circuit 61 is a circuit that includes the X-axis angular velocity signal conversion / amplification unit 70D, the X-axis angular velocity range adjustment unit D, the X-axis angular velocity analog filter unit 110D, and the X-axis angular velocity A / D conversion circuit 120D. This first detection circuit 61 performs detection processing of the X-axis acceleration Ax, which is the first physical quantity PQ1, from the first sensor signal SS1.

[0039] First, in the case shown in Figure 5, the first sensor signal SS1 is input to the X-axis angular velocity signal conversion / amplification unit 70A. That is, the first sensor signal SG1 corresponding to the X-axis acceleration Ax is input to the signal conversion / amplification unit 70A, and the electrical signal is converted and amplified.

[0040] Subsequently, the range adjustment unit adjusts the range of the physical quantity. For example, when the first sensor signal SS1 of the X-axis acceleration Ax corresponding to the first physical quantity PQ1 is input, the X-axis acceleration range adjustment unit 80A of the first detection circuit 61 adjusts the range of the X-axis acceleration Ax based on the signal.

[0041] Here, the X-axis acceleration range adjustment unit 80A can adjust the range based on physical quantities other than the first physical quantity PQ1, which is the X-axis acceleration Ax. Specifically, the detection result of the X-axis angular velocity ωx is fed back as the second physical quantity PQ2, based on the calculation processing result by the range setting unit 140, and input to the X-axis acceleration range adjustment unit 80A, which corresponds to the first detection circuit 61. In other words, the X-axis acceleration range adjustment unit 80A of the first detection circuit C1 can adjust the range of the first physical quantity PQ1 not only using the X-axis acceleration Ax of the first physical quantity PQ1, but also using the information of the X-axis angular velocity ωx of the second physical quantity PQ2.

[0042] Subsequently, the X-axis acceleration analog filter unit 110A filters the sensor signal output by the X-axis acceleration range adjustment unit 80A. Specifically, as mentioned above, it performs low-pass filtering to remove high-frequency components. Then, the A / D conversion circuit 120 converts the analog signal from the analog filter unit 110 into a digital signal. This digital output signal is output from the first detection circuit 61 as the first detection information DI1.

[0043] Thus, the first detection circuit C1 performs processing such as signal conversion, amplification, filtering, and analog-to-digital conversion to detect the first physical quantity PQ1. Similarly, the second detection circuit C2 performs processing to detect the second physical quantity PQ2. These processes together are called detection processing. Although the above explanation uses the first physical quantity PQ1 and the second physical quantity PQ2 as examples, the same applies to the third physical quantity PQ3, which will be explained in "2. Second Embodiment" below.

[0044] The first detection information DI1 from the first detection circuit 61 is input to the digital filter 130A, the attitude calculation unit 150, and the range setting unit 140. The digital filters 130A to 130F each perform processing to reduce noise and other imperfections contained in the electrical signal, and output the corresponding acceleration or angular velocity as the output result of the inertial sensor 1. The attitude calculation unit 150 receives the first detection information DI1 and the second detection information DI2 and performs attitude calculations. As explained in Figure 1, attitude can be expressed, for example, by Euler angles or quaternions. Euler angles specify attitude using three angles: roll angle φ, pitch angle θ, and yaw angle ψ. Information for specifying such attitude can be obtained by integrating, for example, the X-axis angular velocity ωx, Y-axis angular velocity ωy, and Z-axis angular velocity ωz contained in the output signals of the first sensor 51 and the second sensor 52 with respect to time. The attitude calculation unit 150 outputs the calculation result as output information about the attitude of the inertial sensor 1. Furthermore, the posture calculation unit 150 also outputs posture information to the range setting unit 140.

[0045] As described above, the range setting unit 140 determines whether or not to adjust the range of the inertial sensor 1 based on the output results of the attitude calculation unit 150 and the first sensor 51 and the second sensor 52. Here, the range setting unit 140 may be located inside the IC of the inertial sensor 1, or it may be incorporated into software, for example, outside the inertial sensor 1. In other words, in this embodiment, the physical quantity to be detected is predicted using angular velocity, acceleration, and attitude information obtained from the inertial sensor 1, and the dynamic range is set to an appropriate range. Various methods can be envisioned for using this information. Therefore, the acceleration sensor and gyro sensor do not need to be an integrated unit, and 3-axis acceleration and 3-axis angular velocity are not essential configurations. For example, in a configuration of a 3-axis acceleration sensor and a 1-axis gyro sensor, 3-axis acceleration and 1-axis angular velocity may be used to determine the range change of the 1-axis gyro sensor.

[0046] In the example shown in Figure 5, the first physical quantity PQ1 was defined as the X-axis acceleration Ax and the second physical quantity PQ2 as the X-axis angular velocity ωx. However, the first physical quantity PQ1 and the second physical quantity PQ2 can be arbitrarily specified as long as they are different physical quantities.

[0047] Next, we will examine the relationship between acceleration and angular velocity. Rigid body motion includes translational motion and rotational motion, and the inertial sensor 1 detects the acceleration or angular velocity associated with these motions. Based on this information, it also detects the Euler angle to determine the attitude. That is, the acceleration Ain applied externally to the inertial sensor 1 is expressed by equation (1).

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[0048] In equation (1), the first term A is dynamic acceleration, specifically consisting of translational acceleration and rotational acceleration. The second term g is static acceleration, corresponding to gravitational acceleration. The first term A can be further classified into translational acceleration and rotational acceleration, and is expressed as shown in equation (2).

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[0049] In equation (2), the first term is the acceleration of translational motion. The second, third, and fourth terms are the accelerations associated with the rotational motion described above. Specifically, the second term is called centripetal acceleration and exhibits behavior proportional to the square of the angular velocity. The third term is called tangential acceleration or Euler acceleration and exhibits behavior proportional to the derivative of the angular velocity. The fourth term is the acceleration corresponding to the Coriolis force and exhibits behavior proportional to the angular velocity. Of these accelerations associated with rotational motion, the centripetal acceleration (second term) and the tangential acceleration (third term) are particularly prominent when there is a rapid change in angular velocity.

[0050] Figure 7 illustrates tangential acceleration, and Figure 8 illustrates centripetal acceleration. First, let's refer to Figure 7 and specifically examine tangential acceleration. Generally, when a rigid body at position vector r=(rx, ry, rz) from the origin O is undergoing rotational motion, the tangential acceleration acting on the rigid body can be expressed by equation (3) using the time derivative of its angular velocity vector ω.

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[0051] Therefore, as shown in Figure 7, if we assume that the position vector r from the origin O is represented by equation (4) indicating the +Y direction and the angular velocity vector ω is represented by equation (5) indicating the +Z direction, then the tangential acceleration can be obtained as shown in equation (6) using a matrix corresponding to the cross product of the time derivative of the angular velocity vector ω and the position vector r.

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[0052] In other words, if a rigid body located at a position represented by a position vector in the Y-axis direction relative to the origin O is undergoing rotational motion with the axis of rotation in the Z-direction, then as the angular velocity ω of that rotational motion changes over time along the Z-axis, an acceleration in the tangential direction, which is the -X-axis direction, will be generated.

[0053] Next, we will specifically examine centripetal acceleration with reference to Figure 8. Similar to the case in Figure 7, when a rigid body at position vector r=(rx, ry, rz) from the origin O is undergoing rotational motion, the centripetal acceleration acting on the rigid body is expressed by equation (7), using the matrix corresponding to the cross product of its angular velocity vector ω.

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[0054] Therefore, as explained in Figure 7, if the position vector r from the origin O is given by equation (3) and the angular velocity vector ω is given by equation (4), then the centripetal acceleration can be calculated as shown in equation (8).

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[0055] In other words, if a rigid body located at a position represented by a position vector in the Y-axis direction relative to the origin O is undergoing rotational motion with the Z-axis as its axis of rotation, then a centripetal acceleration in the -Y-axis direction will be generated.

[0056] Thus, the acceleration applied to the inertial sensor 1 includes acceleration generated by rotational motion. In other words, acceleration has a correlation with angular velocity.

[0057] Next, let us consider the inertial sensor disclosed in Patent Document 1. In this inertial sensor, the detection circuit adjusts the range by changing the voltage value per unit physical quantity based on the output signal that has passed through the analog filter section. Then, the determination circuit expands the range when the output signal exceeds a preset first threshold and narrows the range when it falls below a second threshold. In this way, the inertial sensor is able to detect both slow and rapid movements.

[0058] However, in this inertial sensor, range adjustment for a given physical quantity is performed based solely on information about that physical quantity. As explained in Figures 7 and 8, the acceleration applied to the inertial sensor includes not only translational acceleration but also acceleration components resulting from rotational motion, such as centripetal acceleration and tangential acceleration, and these accelerations have a correlation with angular velocity. If range adjustment is performed based solely on the angular velocity when detecting a given angular velocity, the correlation between angular velocity and acceleration cannot be taken into account. As a result, the angular velocity to be detected cannot be predicted with sufficient accuracy, and problems occur in the range adjustment based on it. Consequently, this inertial sensor suffers from the problem of not being able to accurately detect acceleration, angular velocity, or attitude information based on these.

[0059] Furthermore, since range adjustment is determined based on only one physical quantity, even if the movement input to the detection axis is small, if the movement in the overall 3D space is large, the dynamic range will be set to be small relative to the overall movement. Moreover, because the principle is that the dynamic range only changes when the detection axis of the inertial sensor shifts to the physical quantity that is the main target of the fluctuation, there is a possibility that the inertial sensor will be slow to track changes in the physical quantity. Consequently, if a large movement of the physical quantity exceeding the range is input before the dynamic range is changed, the output signal may saturate and result in an error. Thus, with the conventional configuration, problems arise because range adjustment is performed based only on the detected physical quantity.

[0060] Furthermore, in the inertial sensor disclosed in Patent Document 1, range adjustment is performed based on the relationship between the magnitude of the output signal and the threshold. Therefore, if the physical quantity continues to change near the threshold, range adjustment may occur frequently. In general inertial sensors, the dynamic range change is adjusted by the amplification gain of the electrical signal, and if the amplification gain is large, the noise superimposed on the output signal will be large. Consequently, if the range is changed frequently, the change will be superimposed on the output signal as detection noise, causing a decrease in the detection accuracy of the physical quantity by the inertial sensor.

[0061] In this regard, the inertial sensor 1 of this embodiment predicts the magnitude of the input angular velocity or acceleration using information on angular velocity, acceleration, and attitude obtained from the inertial sensor 1, and adjusts the dynamic range to an appropriate range.

[0062] For example, as shown in equation (6) above, acceleration A also has a degree component that arises with rotational motion, and the value of the physical quantity being detected cannot be predicted with sufficient accuracy using only the physical quantity being detected. Therefore, when adjusting the range of the first physical quantity PQ1 as described above, by using information from the second physical quantity PQ2, which is a physical quantity other than the first physical quantity P1, the value of the first physical quantity PQ1 can be predicted with high accuracy, and the dynamic range of the first physical quantity PQ1 can be set to a more appropriate range. In this way, when there is a sudden change in angular velocity or when a large angular velocity is input, the signs of this can be predicted with high accuracy. Therefore, it becomes possible to detect physical quantities under an appropriate range setting.

[0063] As described above, the inertial sensor 1 of this embodiment includes a first sensor S1 for detecting a first physical quantity PQ1 on the first axis A1, a first detection circuit C1 that performs detection processing for the first physical quantity PQ1 based on a first sensor signal SG1 from the first sensor S1 and outputs first detection information DI1, a second sensor S2 for detecting a second physical quantity PQ2 on the second axis A2, a second detection circuit C2 that performs detection processing for the second physical quantity PQ2 based on a second sensor signal SG2 from the second sensor S2 and outputs second detection information DI2, and a range setting unit that performs range setting processing. The range setting unit includes range setting processing that sets the detection range of the first physical quantity in the first detection circuit based on the first detection information DI1 and the second detection information DI2.

[0064] In this way, the inertial sensor 1 can set the detection range for detecting the first physical quantity PQ1 based not only on the first physical quantity PQ1 but also on the second physical quantity PQ2. Therefore, for example, the magnitude of the angular velocity ω and acceleration A input to the inertial sensor 1 can be predicted using information on the angular velocity ω, acceleration A, or attitude obtained from the inertial sensor 1, and an appropriate dynamic range can be set. Thus, with an appropriate range setting, high-precision detection of the physical quantities input to the inertial sensor 1 becomes possible.

[0065] 2. Second Embodiment Next, a second embodiment will be described. The second embodiment is an embodiment that utilizes the property that centripetal acceleration and tangential acceleration are generated by rotational motion.

[0066] For example, when a car turns, tangential acceleration is generated as the car rotates at a yaw angle ψ. When a large X-axis acceleration Ax is detected, a rapid change in the Z-axis angular velocity ωz is expected from the third term of equation (2) mentioned above. Therefore, when the X-axis acceleration Ax exceeds a certain threshold, the range setting for the Z-axis angular velocity ωz is increased. For example, when the X-axis acceleration Ax exceeds 1000 (mG), the range of the Z-axis angular velocity ωz is changed from ±100 (deg / s) to ±150 (deg / s). In this way, in the second embodiment, the detection range of the Z-axis angular velocity ωz is increased when the X-axis acceleration Ax exceeds a certain threshold. This makes it possible to respond to rapid changes in the Z-axis angular velocity ωz and prevents a decrease in detection accuracy.

[0067] Furthermore, in the above embodiment, the detection range of the Z-axis angular velocity ωz may be increased when the Y-axis acceleration Ay exceeds a certain threshold. For example, when the Y-axis acceleration Ay exceeds 1000 (mG), the range of the Z-axis angular velocity ωz can be changed from ±100 (deg / s) to ±150 (deg / s). The same effect can be obtained in this way as well.

[0068] In this embodiment, the first axis A1 is the Z-axis, the first physical quantity PQ1 is the Z-axis angular velocity ωz, which is the angular velocity around the Z-axis, the second axis A2 is the X-axis or the Y-axis, and the second physical quantity PQ2 is the X-axis acceleration Ax, which is the acceleration in the X-axis direction, or the Y-axis acceleration Ay, which is the acceleration in the Y-axis direction.

[0069] In this way, the range adjustment of the Z-axis angular velocity ωz can be set not only using the Z-axis angular velocity ωz, but also using the X-axis acceleration Ax or Y-axis acceleration Ay. Therefore, the dynamic range of the Z-axis angular velocity ωz can be set to an appropriate range, and the Z-axis angular velocity ωz can be detected with high accuracy.

[0070] In this embodiment, the range setting unit sets the detection range of the Z-axis angular velocity ωz to be increased when the X-axis acceleration Ax or Y-axis acceleration Ay exceeds a threshold.

[0071] In this way, rapid changes in the Z-axis angular velocity ωz can be predicted from the detected value of the X-axis acceleration Ax. Therefore, it becomes possible to respond to rapid changes in the Z-axis angular velocity ωz, improving the detection accuracy of the physical quantities of the inertial sensor 1.

[0072] Furthermore, from equation (3), for example, the tangential acceleration of the X-axis is calculated based on the time rate of change of the Z-axis angular velocity ωz and the Y-axis angular velocity ωy, as well as the Y-coordinate ry and Z-coordinate rz from the origin O during the rotational motion of each axis. Therefore, the range of the X-axis acceleration Ax can be set based on the time rate of change of the Z-axis angular velocity ωz and the Y-axis angular velocity ωy, and the detected values ​​of the Y-coordinate ry or Z-coordinate rz. For example, from the X-axis component of equation (3), if the absolute value of the product of the time rate of change of the Z-axis angular velocity and the Y-coordinate ry, i.e., the first term, is small, and the product of the time rate of change of the Y-axis angular velocity ωy and the Z-coordinate rz, i.e., the second term, is large, then it is predicted that the tangential acceleration of the X-axis acceleration Ax will be large. In such cases, by adjusting the range to increase the range of the X-axis acceleration Ax, the X-axis acceleration Ax can be detected accurately under an appropriate range setting.

[0073] When using three or more physical quantities to adjust the range of a certain physical quantity, a third physical quantity PQ3 can be introduced in addition to the first physical quantity PQ1 and the second physical quantity PQ2. In the example above, the first physical quantity PQ1 can be the Z-axis angular velocity ωz, the second physical quantity PQ2 can be the Y-axis angular velocity ωy, and the third physical quantity PQ3 can be the Y-coordinate ry or the Z-coordinate rz. The detection process for the third physical quantity PQ3 is performed by a third sensor 53 (not shown in Figure 5), and the third sensor 53 outputs the third detection information DI3 to the range setting unit 140, the attitude calculation unit 150, and the digital filter corresponding to the third physical quantity PQ3.

[0074] In other words, this embodiment includes a third sensor S3 for detecting a third physical quantity PQ3 on the third axis A3, and a third detection circuit 63 that performs detection processing of the third physical quantity PQ3 based on the third sensor signal SS3 from the third sensor S3 and outputs third detection information DI3. The range setting unit performs range setting processing to set the detection range of the first physical quantity PQ1 based on the first detection information DI1, the second detection information DI2, and the third detection information DI3.

[0075] In this way, the range of the first physical quantity PQ1 can be adjusted using the second physical quantity PQ2 and the third physical quantity PQ3, which are physical quantities other than the first physical quantity PQ1. Therefore, the range of the first physical quantity PQ1 can be adjusted more appropriately, and the detection accuracy of the physical quantity of the inertial sensor 1 can be improved.

[0076] In the above description, we explained the case in which a third physical quantity PQ3 is introduced in addition to the first physical quantity PQ1 and the second physical quantity PQ2. However, in this embodiment, there is no limit to the number of physical quantities that can be used to adjust the range of the first physical quantity PQ1. Therefore, physical quantities other than the third physical quantity PQ3 can also be introduced.

[0077] 3. Third Embodiment Next, a third embodiment will be described. Figure 9 is a diagram illustrating an example of a specific range adjustment method when the third embodiment is applied. This method involves setting a range for a certain physical quantity and a corresponding threshold, and performing range adjustment based on the relationship between the detected value of the physical quantity and the threshold. Here, the range refers to the range that covers the expected range of fluctuation of the physical quantity to be detected. The threshold is a value that determines the magnitude relationship of the physical quantities, which is determined, for example, by multiplying the range by a predetermined ratio.

[0078] The graph in Figure 9 shows the time evolution of the Z-axis angular velocity ωz, with the horizontal axis representing time (s) and the vertical axis representing the Z-axis angular velocity ωz (deg / s). In the example shown in Figure 9, two ranges, the first range RA1 and the second range RA2, are set for the Z-axis angular velocity ωz, and thresholds, the first threshold TH1 and the second threshold TH2, are set for each range. Here, the values ​​of the first threshold TH1 and the second threshold TH2 are set to 50% of the values ​​of the first range RA1 and the second range RA2, respectively. That is, for the first range RA1 of 100 (deg / s), the first threshold TH1 is set to 50 (deg / s), and for the second range RA2 of 300 (deg / s), the second threshold TH2 is set to 150 (deg / s). Furthermore, the ratio of the threshold to the range may differ between the first threshold TH1 and the second threshold TH2, and the second threshold TH2 may be set to 210 (deg / s), which is 70% of the second range RA2. In other words, the predetermined ratio for determining the threshold corresponding to each range can be freely determined.

[0079] Using Figure 9 to explain the specific process, during the period from time 0 to t1, the Z-axis angular velocity ωz is close to 0 and within the range of the first range RA1. After time t1, the Z-axis angular velocity ωz begins to increase and at time t2 it becomes greater than the first threshold TH1 of 50 (deg / s). Therefore, the range setting unit adjusts the range at time t2 and changes the range setting to the second range RA2 of 300 (deg / s). After time t2, the Z-axis angular velocity ωz begins to decrease without exceeding the second threshold TH2 of the second range RA2 of 150 (deg / s), and at time t3 it decreases to a value less than or equal to the first threshold TH1 of 50 (deg / s).

[0080] Then, at time t4, the range setting unit adjusts the range and returns the range setting to the first range RA1 at 100 (deg / s). Here, as shown in Figure 9, the Z-axis angular velocity ωz decreases to below the first threshold TH1 at time t3, but the range setting unit maintains the range setting to the second range RA2 for 10 seconds even after the Z-axis angular velocity ωz has fallen below the first threshold TH1. At time t4, 10 seconds after the angular velocity has fallen below the second threshold TH2, the range setting unit returns the range setting to the first range RA1.

[0081] In this way, even if the physical quantity being detected falls below a corresponding threshold within a certain range, maintaining the current range setting for a predetermined period avoids frequent changes to the range setting and suppresses the detection noise of the physical quantity that would otherwise occur. For example, the physical quantity being detected may frequently fluctuate around a threshold, and changing the range each time in this case would result in detection noise. From this perspective, it is desirable to maintain the current range setting for a predetermined period when the detected value of the physical quantity falls below the threshold. Note that the predetermined period is set to 10(s) in Figure 9, but it is not limited to this.

[0082] In other words, in this embodiment, when the first detection circuit C1 is performing the detection process of the first physical quantity PQ1 in the first range RA1, the range setting unit sets the detection range of the first physical quantity PQ1 to the second range RA2, which is larger than the first range RA1, when the detected value of the first detection information DI1 exceeds the first threshold TH1 within the first range RA1.

[0083] In this way, the detection range of the physical quantity to be detected can be determined by the relationship between the threshold value and the detected value, allowing for the setting of an appropriate range at each point in time. Furthermore, by setting threshold values ​​corresponding to each range, the range adjustment process can be executed flexibly.

[0084] Figure 10 shows an example of angular velocity ω data actually output by an inertial sensor 1 mounted on a vehicle or other vehicle traveling on a road surface. In Figure 10, the horizontal axis of each graph is time (s), and the vertical axis is the X-axis angular velocity ωx (deg / s) for the upper graph, the Y-axis angular velocity ωy (deg / s) for the middle graph, and the Z-axis angular velocity ωz (deg / s) for the lower graph. Specifically, the X-axis angular velocity ωx corresponds to the rotational angular velocity around the vehicle's longitudinal axis. The Y-axis angular velocity ωy and Z-axis angular velocity ωz correspond to the rotational angular velocity around the vehicle's lateral axis and vertical axis, respectively. The predetermined period on the left side of each graph shows the behavior of each angular velocity ω when the vehicle is stopped, and the right side shows the behavior of the angular velocity ω when traveling in a straight line. When the vehicle is stopped, each angular velocity ω is constant at 0, but when straight-line travel begins, large data fluctuations appear in both the X-axis angular velocity ωx and the Y-axis angular velocity ωy. When vehicles travel on a road surface, the X-axis angular velocity ωx and Y-axis angular velocity ωy undergo rapid changes due to the effects of road surface irregularities. Due to these factors, large changes in the X-axis angular velocity ωx and Y-axis angular velocity ωy are observed in the upper and middle graphs of Figure 10. On the other hand, the Z-axis angular velocity ωz, shown in the lower graph, differs from the X-axis angular velocity ωx and Y-axis angular velocity ωy in that the fluctuation of the angular velocity remains within a relatively gradual range. This is because the Z-axis angular velocity ωz is mainly detected when vehicles turn right or left, and is less likely to occur during straight-line driving.

[0085] As shown in Figure 10, the angular velocity of the X-axis ωx and Y-axis ωy fluctuates rapidly in a short time, so it is desirable to set a wide initial setting for the dynamic range of the angular velocity. Here, the initial setting refers to, for example, the first state when a car attempts to start moving from a stationary position, and also includes the first state when attempting to start moving from a stopped position. Therefore, when the setting ranges for the dynamic ranges of the X-axis angular velocity ωx, Y-axis angular velocity ωy, and Z-axis angular velocity ωz are Rωx, Rωy, and Rωz respectively, setting the dynamic range so that Rωz≦Rωx or Rωz≦Rωy can accommodate the rapid fluctuations in angular velocity described above. In this way, a decrease in the detection accuracy of the inertial sensor 1 can be prevented. For example, the dynamic range can be initially set to Rωx=±200(deg / s), Rωy=±200(deg / s), and Rωz=±100(deg / s) when the inertial sensor 1 is started. Note that the initial setting for the dynamic range does not have to be Rωx=Rωy as described above.

[0086] In other words, in this embodiment, the first axis A1 is the X-axis or the Y-axis, the first physical quantity PQ1 is the X-axis angular velocity ωx or the Y-axis angular velocity ωy, the second axis A2 is the Z-axis, the second physical quantity PQ2 is the Z-axis angular velocity ωz, and the range setting unit, in its initial setting, sets the detection range for the Z-axis angular velocity to a size less than or equal to the detection range for the X-axis angular velocity ωx or the Y-axis angular velocity ωy.

[0087] In this way, the Z-axis angular velocity ωz can be detected with high accuracy, while also being able to respond to rapid changes in the X-axis and Y-axis angular velocities ωx and ωy, thereby preventing a decrease in the detection accuracy of physical quantities in the inertial sensor 1.

[0088] Figure 11 shows an example of acceleration A data output by an inertial sensor 1 mounted on a vehicle traveling on a road surface, similar to Figure 10. Similar to Figure 10, the horizontal axis represents time (s), and the vertical axis shows the X-axis acceleration Ax (mG) in the upper graph, the Y-axis acceleration Ay (mG) in the middle graph, and the Z-axis acceleration Az (mG) in the lower graph. X-axis acceleration Ax represents the acceleration in the longitudinal direction of the vehicle, while Y-axis acceleration Ay and Z-axis acceleration Az represent the acceleration in the lateral and vertical directions of the vehicle, respectively. Similar to Figure 10, the acceleration is constant at 0 when the vehicle is stopped, but changes appear in each acceleration when straight-line travel begins. As in Figure 10, vehicles traveling on a road surface are strongly affected by road surface irregularities. That is, the Z-axis acceleration changes rapidly due to vertical vibrations in addition to gravitational acceleration. Due to these factors, Figure 11 shows relatively gradual changes in the X-axis acceleration Ax and Y-axis acceleration Ay, as shown in the upper and middle sections, but a rapid change in the Z-axis acceleration Az, as shown in the lower section. Therefore, in order to keep up with the Z-axis acceleration, which fluctuates rapidly in a short time, it is desirable to set a wide initial dynamic range for the Z-axis acceleration. Accordingly, when the setting ranges for the dynamic ranges of the X-axis acceleration Ax, Y-axis acceleration Ay, and Z-axis acceleration Az are set to RAx, RAy, and RAz respectively, setting the dynamic range so that RAz≧RAx or RAz≧RAy can accommodate the rapid changes in angular velocity described above. In this way, a decrease in the detection accuracy of the inertial sensor 1 can be prevented. For example, it is conceivable to set the dynamic range to RAx=±2(G), RAy=±2(G), and RAz=±8(G) when the inertial sensor 1 is started. Note that the initial setting of the dynamic range does not have to be RAx=RAy as described above. Furthermore, although the acceleration due to gravity is removed in the above calculation, inertial sensor 1 detects acceleration with the addition of approximately 1000 (mG) of the acceleration due to gravity.

[0089] In other words, in this embodiment, the first axis A1 is the X-axis or the Y-axis, the first physical quantity PQ1 is the X-axis acceleration Ax or the Y-axis acceleration Ay, the second axis A2 is the Z-axis, the second physical quantity PQ2 is the Z-axis acceleration Az, and the range setting unit is characterized in that, in the initial setting, the detection range of the Z-axis acceleration Az is set to be greater than or equal to the detection range of the X-axis acceleration Ax or the Y-axis acceleration Ay.

[0090] In this way, the Z-axis acceleration Az can be detected with high accuracy while also responding to rapid changes in the X-axis acceleration Ax and Y-axis acceleration Ay. This prevents a decrease in the detection accuracy of physical quantities in the inertial sensor 1.

[0091] 4. Fourth Embodiment Next, a fourth embodiment will be described. The fourth embodiment is an embodiment that uses the correlation between angular velocity and the yaw angle ψ which determines attitude. As explained in Figure 6, attitude can be determined using, for example, Euler angles. Euler angles are calculated, for example, by integrating the gyro sensor output over time, and the roll angle φ, pitch angle θ, and yaw angle ψ are related to the X-axis angular velocity ωx, Y-axis angular velocity ωy, and Z-axis angular velocity ωz in the relationship given by equation (9).

number

[0092] Equation (9) is a theoretical formula for calculating the time change of attitude or azimuth from the angular velocity ω. Then, integrating both sides of equation (9) with respect to time yields equation (10), which shows the change in attitude.

number

[0093] From equation (10), it can be seen that calculating the yaw angle ψ requires not only the angular velocity of the Z component, but also information on the roll angle φ and pitch angle θ. This corresponds to the fact that, for example, an automobile has a certain degree of tilt relative to the ground, and in order to accurately detect its attitude, it is necessary to correct for this tilt using the roll angle φ and pitch angle θ. Therefore, in order to accurately detect the yaw angle ψ, it is important to detect the X-axis angular velocity ωx and Y-axis angular velocity ωy, which are the time derivatives of the roll angle φ and pitch angle θ, with high precision. Here, if the Z-axis angular velocity ωz is already a large value, there is a limit to how much detection noise can be reduced by reducing the range of the Z-axis angular velocity ωz. On the other hand, there may still be room to adjust the range for the X-axis angular velocity ωx and Y-axis angular velocity ωy. Therefore, in the fourth embodiment, if the angular velocity of the Z-axis angular velocity ωz exceeds a certain threshold, the detection range of the X-axis angular velocity ωx or Y-axis angular velocity ωy is reduced. In this way, by reducing the range of the X-axis angular velocity ωx or the Y-axis angular velocity ωy, it is possible to improve the detection accuracy of the yaw angle ψ, which determines the attitude, while maintaining the detection accuracy of the Z-axis angular velocity ωz.

[0094] Figure 12 is a table showing examples of range setting and threshold change patterns for each physical quantity when using the fourth embodiment. For example, in the example in Figure 12, the range settings for the X-axis angular velocity ωx and Y-axis angular velocity ωy are set to ±200 (deg / s) in the initial state, and the range setting for the Z-axis angular velocity ωz is set to ±100 (deg / s). Then, in the first state, when the Z-axis angular velocity ωz becomes ±45 (deg / s) and exceeds the first threshold TH1 of 30 (deg / s), the range setting unit reduces the range of the X-axis angular velocity ωx and Y-axis angular velocity ωy to ±150 (deg / s) and performs range adjustment to maintain the Z-axis angular velocity ωz at ±100 (deg / s). In this way, detection noise can be reduced by reducing the range of the X-axis angular velocity ωx and Y-axis angular velocity ωy while covering the detection range of the increased Z-axis angular velocity ωz.

[0095] In the second state, the Z-axis angular velocity ωz has increased to ±55 (deg / s), which is greater than the second threshold TH2 of 50 (deg / s) for the Z-axis angular velocity ωz. Therefore, the range of the Z-axis angular velocity ωz is increased to ±200 (deg / s), and the ranges of the X-axis angular velocity ωx and the Y-axis angular velocity ωy are reduced to 150 (deg / s) by the amount by which the range of the Z-axis angular velocity ωz has increased. By doing so, it is possible to suppress an increase in detection noise by reducing the ranges of the X-axis angular velocity ωx and the Y-axis angular velocity ωy while covering the detection range of the increased Z-axis angular velocity ωz. In the right column of FIG. 12, the magnitude relationships of the ranges of the respective physical quantities are shown. Let the widths of the ranges of the X-axis angular velocity ωx, the Y-axis angular velocity ωy, and the Z-axis angular velocity ωz be X, Y, and Z, respectively. In the initial state, the first state, and the second state, the magnitude relationships of the ranges of the respective physical quantities are maintained. The third state and the fourth state are cases where the Z-axis angular velocity ωz has increased from the initial state, and further, the X-axis angular velocity ωx or the Y-axis angular velocity ωy has also increased. In such a case, since there is no room to reduce the range for the physical quantity whose detected value has increased, only the physical quantity whose detected value has not increased is processed to reduce the range. For example, in the third state, only the X-axis angular velocity ωx, whose detected value remains at ±5 (deg / s) and has not increased, is processed to reduce the range to 150 (deg / s). By doing so, for the Z-axis angular velocity ωz and the X-axis angular velocity ωx or the Y-axis angular velocity ωy whose detected values have increased, high-precision detection of the physical quantity is maintained, and for the X-axis angular velocity ωx or the Y-axis angular velocity ωy for which there is room to reduce the range, the range is reduced, thereby suppressing the detection noise of the inertial sensor 1. In the third state and the fourth state, the magnitude relationship of the ranges shown in the right column of FIG. 12 has changed from the initial state. In the third state, it is Z < X < Y, and in the fourth state, it is Z < Y < Z. Thus, not limited to the magnitude relationships of the range settings in each state shown in FIG. 12, various range adjustment patterns can be considered.

[0096] That is, in the present embodiment, when the Z-axis angular velocity ωz exceeds the threshold value, the range setting unit performs a setting to reduce the detection range of the X-axis angular velocity ωx or the Y-axis angular velocity ωy.

[0097] In this way, detection noise in the inertial sensor 1 can be suppressed by reducing the range of the X-axis angular velocity ωx and Y-axis angular velocity ωy while covering the detected value of the Z-axis angular velocity ωz. Therefore, the inertial sensor 1 can detect the yaw angle ψ of the Euler angle with high accuracy.

[0098] 5. Fifth Embodiment Finally, the fifth embodiment will be described. The fifth embodiment, like the fourth embodiment, is an example in which attitude information is used to adjust the range of physical quantities. From equation (10) mentioned above, information on the roll angle φ and pitch angle θ is necessary to calculate the yaw angle ψ. Specifically, the roll angle φ and pitch angle θ are included in the coefficients of the Y-axis angular velocity ωy and Z-axis angular velocity ωz in equation (10), and when the roll angle φ and pitch angle θ are large, they greatly affect the contribution of the Y-axis angular velocity ωy and Z-axis angular velocity ωz to the calculation of the yaw angle ψ. Therefore, in the fifth embodiment, when the roll angle φ and pitch angle θ exceed a certain threshold, the range of the X-axis angular velocity ωx or Y-axis angular velocity ωy can be reduced. In this way, when the roll angle φ or pitch angle θ exceeds a certain threshold, the detection accuracy of the yaw angle ψ can be expected to be improved by reducing the range of the X-axis angular velocity ωx or Y-axis angular velocity ωy.

[0099] Figure 13 is a table showing examples of range setting and threshold change patterns for each physical quantity when using the fifth embodiment. In the initial state, the roll angle φ and pitch angle θ are 0, and the range of the X-axis angular velocity ωx is set to ±200 (deg / s), and the range of the Y-axis angular velocity ωy is set to ±200 (deg / s). Then, in the first state, if the roll angle φ and pitch angle θ exceed the set threshold of ±5 (deg) due to conditions such as severe road surface irregularities, and reach ±6 (deg), the ranges of the X-axis angular velocity ωx and Y-axis angular velocity ωy are changed to 150 (deg / s). Also, if the detected value of the Y-axis angular velocity ωy is small, the Y-axis angular velocity ωy range can be reduced to ±100 (deg / s), as shown in the second state. On the other hand, the third and fourth states are cases where either the X-axis angular velocity ωx or the Y-axis angular velocity ωy is a large value of ±45 (deg / s). In the third state, since the Y-axis angular velocity ωy is large, there is no room to further reduce the Y-axis angular velocity ωy. Therefore, the range of the Y-axis angular velocity ωy is maintained at ±200 (deg / s), and only the range of the X-axis angular velocity ωx is changed to 150 (deg / s). In this way, detection noise can be reduced by lowering the range of the X-axis angular velocity ωx while maintaining the detection accuracy of the Y-axis angular velocity ωy, and the yaw angle ψ can be detected with high accuracy. Note that, as explained in Figure 12, the relative magnitudes of the range settings after range adjustment are not limited to the cases of the first to fourth states shown in Figure 13.

[0100] In this embodiment, a posture calculation unit 150 is included that determines posture information of the object to be measured based on the first detection information DI1 and the second detection information DI2, and the range setting unit performs range setting processing based on the posture information obtained by the posture calculation unit 150.

[0101] As shown in equation (10), for example, Δψ, which indicates a change in attitude, is calculated based on the Y-axis angular velocity ωy, the Z-axis angular velocity ωz, and the roll angle φ and pitch angle θ that identify the attitude before the change. Therefore, according to this embodiment, the attitude calculation unit 150 can calculate the current attitude by determining the change in yaw angle ψ Δψ using, for example, the Y-axis angular velocity ωy and the Z-axis angular velocity ωz. Accordingly, the range setting unit can perform more accurate range adjustment by using attitude information such as Δψ calculated by the attitude calculation unit 150 in addition to acceleration A and angular velocity ω. Thus, the inertial sensor 1 can detect physical quantities with high accuracy.

[0102] In this embodiment, the first axis A1 is either the X-axis or the Y-axis, the first physical quantity PQ1 is the X-axis angular velocity ωx or the Y-axis angular velocity ωy, the attitude calculation unit 150 obtains the roll angle φ or the pitch angle θ as attitude information, and the range setting unit sets the detection range of the X-axis angular velocity ωx or Y-axis angular velocity ωy to be smaller when the roll angle φ or pitch angle θ exceeds a threshold.

[0103] In this way, when the roll angle φ or pitch angle θ exceeds a certain threshold, the detection noise of the inertial sensor 1 can be suppressed by reducing the range of the X-axis angular velocity ωx or Y-axis angular velocity ωy. Therefore, the inertial sensor 1 can detect the yaw angle ψ with high accuracy.

[0104] In other words, in this embodiment, the first axis A1 is the X-axis or the Y-axis, the first physical quantity PQ1 is the X-axis angular velocity ωx or the Y-axis angular velocity ωy, the second axis A2 is the Z-axis, the second physical quantity PQ2 is the Z-axis angular velocity ωz, and the range setting unit, in its initial setting, sets the detection range for the Z-axis angular velocity to a size less than or equal to the detection range for the X-axis angular velocity ωx or the Y-axis angular velocity ωy.

[0105] In this way, the Z-axis angular velocity ωz can be detected with high accuracy, while also being able to respond to rapid changes in the X-axis and Y-axis angular velocities ωx and ωy, thereby preventing a decrease in the detection accuracy of physical quantities in the inertial sensor 1.

[0106] Furthermore, in this embodiment, the system includes a posture calculation unit 150 that determines posture information of the object to be measured based on the first detection information DI1, the second detection information DI2, and the third detection information DI3, and the range setting unit performs range setting processing based on the posture information determined by the posture calculation unit 150.

[0107] As mentioned above, the change Δψ of the yaw angle ψ, which determines the attitude, is calculated based on the Y-axis angular velocity ωy, the Z-axis angular velocity ωz, and the roll angle φ and pitch angle θ, which determine the attitude before the change. Therefore, according to this embodiment, the attitude calculation unit 150 can calculate the change Δψ of the yaw angle ψ with greater accuracy by using the Y-axis angular velocity ωy and the Z-axis angular velocity ωz, as well as the attitude information roll angle φ or pitch angle θ. Consequently, the range setting unit can adjust the range using the highly accurate attitude information calculated by the attitude calculation unit 150. Thus, the inertial sensor 1 can detect physical quantities with high accuracy.

[0108] As described above, the inertial sensor of this embodiment includes a first sensor, a first detection circuit, a second sensor, a second detection circuit, and a range setting unit. The first sensor detects a first physical quantity on the first axis. The first detection circuit performs detection processing of the first physical quantity based on the first sensor signal from the first sensor and outputs first detection information. The second sensor detects a second physical quantity on the second axis. The second detection circuit performs detection processing of the second physical quantity based on the second sensor signal from the second sensor and outputs second detection information. The range setting unit performs range setting processing to set the detection range of the first physical quantity in the first detection circuit based on the first detection information and the second detection information.

[0109] According to this embodiment, the inertial sensor can set the detection range for detecting the first physical quantity not only based on the first physical quantity but also on the second physical quantity. Therefore, it becomes possible to set the detection range of the first physical quantity input to the inertial sensor more accurately, enabling high-precision detection of the first physical quantity.

[0110] In this embodiment, the first axis is the X-axis or the Y-axis, and the first physical quantity is the X-axis angular velocity, which is the angular velocity around the X-axis, or the Y-axis angular velocity, which is the angular velocity around the Y-axis. The second axis is the Z-axis, and the second physical quantity is the Z-axis angular velocity, which is the angular velocity around the Z-axis.

[0111] In this way, the Z-axis angular velocity can be predicted using not only the Z-axis angular velocity but also the X-axis or Y-axis angular velocity, allowing for highly accurate prediction of the Z-axis angular velocity. Therefore, based on the accurately predicted value of the Z-axis angular velocity, the detection range of the Z-axis angular velocity can be appropriately set, enabling highly accurate detection of physical quantities by the inertial sensor.

[0112] In this embodiment, the range setting unit reduces the detection range of the X-axis angular velocity ωx or Y-axis angular velocity ωy when the Z-axis angular velocity ωz exceeds a threshold.

[0113] In this way, detection noise from the inertial sensor can be suppressed by reducing the range of X-axis and Y-axis angular velocities while covering the detected values ​​of the Z-axis angular velocity. Therefore, the inertial sensor can detect the yaw angle of the Euler angle with high accuracy.

[0114] In this embodiment, the first axis is the Z-axis, and the first physical quantity is the Z-axis angular velocity, which is the angular velocity around the Z-axis. The second axis is either the X-axis or the Y-axis, and the second physical quantity is either the X-axis acceleration, which is the acceleration in the X-axis direction, or the Y-axis acceleration, which is the acceleration in the Y-axis direction.

[0115] In this way, the range adjustment of the Z-axis angular velocity can be set using not only the Z-axis angular velocity but also the X-axis acceleration or Y-axis acceleration. Therefore, the dynamic range of the Z-axis angular velocity can be set to an appropriate range, and the Z-axis angular velocity can be detected with high accuracy.

[0116] In this embodiment, the range setting unit is configured to increase the detection range of the Z-axis angular velocity when the X-axis acceleration or Y-axis acceleration exceeds a threshold.

[0117] In this way, rapid changes in the Z-axis angular velocity can be predicted from the detected value of the X-axis acceleration. Therefore, it becomes possible to respond to rapid changes in the Z-axis angular velocity, improving the accuracy of the inertial sensor's detection of physical quantities.

[0118] Furthermore, this embodiment includes a posture calculation unit that determines posture information of the object to be measured based on the first detection information and the second detection information, and a range setting unit performs range setting processing based on the posture information determined by the posture calculation unit.

[0119] In this way, the attitude calculation unit can calculate the current attitude by determining the change in yaw angle using, for example, the Y-axis angular velocity and Z-axis angular velocity. Therefore, the range setting unit can perform more accurate range adjustments by using the attitude information calculated by the attitude calculation unit in addition to acceleration and angular velocity. Consequently, the inertial sensor can detect physical quantities with high accuracy.

[0120] In this embodiment, the first axis is the X-axis or the Y-axis, the first physical quantity is the X-axis angular velocity, which is the angular velocity around the X-axis, or the Y-axis angular velocity, which is the angular velocity around the Y-axis, the attitude calculation unit obtains the roll angle, which is the rotation angle around the X-axis, or the pitch angle, which is the rotation angle around the Y-axis, as attitude information, and the range setting unit sets the detection range of the X-axis angular velocity or Y-axis angular velocity to be smaller when the roll angle or pitch angle exceeds a threshold.

[0121] In this way, when the roll angle or pitch angle exceeds a certain threshold, the detection noise of the inertial sensor can be suppressed by reducing the range of the X-axis angular velocity or Y-axis angular velocity. Therefore, the inertial sensor can detect the yaw angle with high accuracy.

[0122] In this embodiment, the first axis is the X-axis or Y-axis, and the first physical quantity is the X-axis angular velocity, which is the angular velocity around the X-axis, or the Y-axis angular velocity, which is the angular velocity around the Y-axis. The second axis is the Z-axis, and the second physical quantity is the Z-axis angular velocity, which is the angular velocity around the Z-axis. In the initial setting, the range setting unit sets the detection range for the Z-axis angular velocity to a size less than or equal to the detection range for the X-axis angular velocity or the Y-axis angular velocity.

[0123] In this way, the Z-axis angular velocity can be detected with high accuracy while also responding to rapid changes in the X-axis and Y-axis angular velocities, thus preventing a decrease in the detection accuracy of physical quantities in the inertial sensor.

[0124] In this embodiment, the first axis is the X-axis or the Y-axis, and the first physical quantity is the X-axis acceleration, which is the acceleration in the X-axis direction, or the Y-axis acceleration, which is the acceleration in the Y-axis direction. The second axis is the Z-axis, and the second physical quantity is the Z-axis acceleration, which is the acceleration in the Z-axis direction. In the initial setting, the range setting unit sets the detection range for the Z-axis acceleration to be greater than or equal to the detection range for the X-axis acceleration or the Y-axis acceleration.

[0125] This approach allows for high-precision detection of Z-axis acceleration while also responding to rapid changes in X-axis and Y-axis acceleration. It prevents a decrease in the detection accuracy of physical quantities in the inertial sensor.

[0126] Furthermore, in this embodiment, the system includes a third sensor for detecting a third physical quantity in the third axis, and a third detection circuit that performs detection processing of the third physical quantity based on the third sensor signal from the third sensor and outputs third detection information. The range setting unit performs range setting processing to set the detection range of the first physical quantity based on the first detection information, the second detection information, and the third detection information.

[0127] In this way, the range of the first physical quantity can be adjusted using the second and third physical quantities, which are physical quantities other than the first physical quantity. Therefore, the range of the first physical quantity can be adjusted more appropriately, and the detection accuracy of the physical quantity by the inertial sensor can be improved.

[0128] In this embodiment, the system includes a posture calculation unit that determines posture information of the object to be measured based on the first detection information, the second detection information, and the third detection information, and the range setting unit performs range setting processing based on the posture information determined by the posture calculation unit.

[0129] In this way, the attitude calculation unit can calculate the change in yaw angle with greater accuracy by using the Y-axis angular velocity, Z-axis angular velocity, and the roll angle or pitch angle of the attitude information. Consequently, the range setting unit can adjust the range using the highly accurate attitude information calculated by the attitude calculation unit, and the inertial sensor can detect physical quantities with high accuracy.

[0130] In this embodiment, when the first detection circuit is performing detection processing for the first physical quantity in the first detection range, the range setting unit sets the detection range for the first physical quantity to a second detection range which is larger than the first detection range when the detected value of the first detection information exceeds the first threshold within the first detection range.

[0131] In this way, the detection range of the physical quantity to be detected can be determined by the relationship between the threshold value and the detected value, allowing for the setting of an appropriate range at each point in time. Furthermore, by setting threshold values ​​corresponding to each range, the range adjustment process can be executed flexibly.

[0132] Although this embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novelty and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure. For example, any term that appears at least once in the specification or drawings together with a broader or synonymous term may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of this embodiment and its modifications are also included within the scope of this disclosure. In addition, the configuration and operation of the inertial sensor are not limited to those described in this embodiment, and various modifications are possible. [Explanation of Symbols]

[0133] 1…Inertial sensor, 30…Detection device, 41…First drive circuit, 42…Second drive circuit, 50A…X-axis acceleration sensor, 50B…Y-axis acceleration sensor, 50C…Z-axis acceleration sensor, 50D…X-axis angular velocity sensor, 50E…Y-axis angular velocity sensor, 50F…Z-axis angular velocity sensor, 51…First sensor, 52…Second sensor, 53…Third sensor, 61…First detection circuit, 62…Second detection circuit, 63…Third detection circuit, 71…First signal conversion / amplification unit, 72…Second signal conversion / amplification unit, 70A…X-axis acceleration signal conversion / amplification unit, 70B…Y-axis acceleration signal conversion / amplification unit, 70C… 70D...Z-axis acceleration signal conversion / amplification unit, 70E...X-axis angular velocity signal conversion / amplification unit, 70F...Y-axis angular velocity signal conversion / amplification unit, 80A...X-axis acceleration range adjustment unit, 80B...Y-axis acceleration range adjustment unit, 80C...Z-axis acceleration range adjustment unit, 80D...X-axis angular velocity range adjustment unit, 80E...Y-axis angular velocity range adjustment unit, 80F...Z-axis angular velocity range adjustment unit, 81...First range adjustment unit, 82...Second range adjustment unit, 110A...X-axis acceleration analog filter unit, 110B...Y-axis acceleration analog filter unit, 110C...Y-axis acceleration analog filter unit 110D…X-axis angular velocity analog filter section, 110E…Y-axis angular velocity analog filter section, 110F…Z-axis angular velocity analog filter section, 111…First analog filter, 112…Second analog filter, 120A…X-axis acceleration A / D conversion circuit, 120B…Y-axis acceleration A / D conversion circuit, 120C…Z-axis acceleration A / D conversion circuit, 120D…X-axis angular velocity A / D conversion circuit, 120E…Y-axis angular velocity A / D conversion circuit, 120F…Z-axis angular velocity A / D conversion circuit, 121…First A / D conversion circuit, 122…Second A / D conversion circuit, 130A…X-axis acceleration digital filter -, 130B...Y-axis acceleration digital filter, 130C...Y-axis acceleration digital filter, 130D...X-axis angular velocity digital filter, 130E...Y-axis angular velocity digital filter, 130F...Z-axis angular velocity digital filter, 131...First digital filter, 132...Second digital filter, 140...Range setting unit, 142...Range change determination unit, 150...Attitude calculation unit, A...Acceleration, A1...First axis, A2...Second axis, A3...Third axis, AGND...Reference power supply voltage, Ain...Acceleration, Ax...Axis acceleration, Ax...X-axis acceleration, Ay...Y-axis acceleration, Az...Z-axis acceleration,CD1…Capacitor, DI1…First detection information, DI2…Second detection information, DI3…Third detection information, DPGA…Adjustment data, G…Gain, ISM…Input signal, ISP…Input signal, ND1…Input node, ND2…Node, ND3…Output node, ND4…Node, O…Origin, OPD1…Operation amplifier, PQ1…First physical quantity, PQ2…Second physical quantity, PQ3…Third physical quantity, QT…Output tap, R2…Resistance value, R3 ...resistance value, RA1...1st range, RA2...2nd range, RD1...resistance, RD2...variable resistor, RD3...variable resistor, S1...1st sensor, S2...2nd sensor, S3...3rd sensor, TH1...1st threshold, TH2...2nd threshold, VS1M...signal, rx...X coordinate, ry...Y coordinate, rz...Z coordinate, θ...pitch angle, φ...roll angle, ψ...yaw angle, ω...angular velocity, ωx...X-axis angular velocity, ωx...Y-axis angular velocity, ωz...Z-axis angular velocity,

Claims

1. A first sensor for detecting a first physical quantity in the first axis, A first detection circuit that performs detection processing of the first physical quantity based on the first sensor signal from the first sensor and outputs first detection information, A second sensor for detecting a second physical quantity in the second axis, A second detection circuit that performs detection processing of the second physical quantity based on the second sensor signal from the second sensor and outputs second detection information, A range setting unit that performs range setting processing, Includes, The range setting unit is, Based on the first detection information and the second detection information, the range setting process is performed to set the detection range of the first physical quantity in the first detection circuit. The first axis is the X-axis or the Y-axis, The first physical quantity is the X-axis angular velocity, which is the angular velocity around the X-axis, or the Y-axis angular velocity, which is the angular velocity around the Y-axis. The second axis is the Z-axis, The inertial sensor is characterized in that the second physical quantity is the Z-axis angular velocity, which is the angular velocity around the Z-axis.

2. In the inertial sensor described in claim 1, The range setting unit is, An inertial sensor characterized by setting the detection range of the X-axis angular velocity or the Y-axis angular velocity to be reduced when the Z-axis angular velocity exceeds a threshold.

3. A first sensor for detecting a first physical quantity in the first axis, A first detection circuit that performs detection processing of the first physical quantity based on the first sensor signal from the first sensor and outputs first detection information, A second sensor for detecting a second physical quantity in the second axis, A second detection circuit that performs detection processing of the second physical quantity based on the second sensor signal from the second sensor and outputs second detection information, A range setting unit that performs range setting processing, Includes, The range setting unit is, Based on the first detection information and the second detection information, the range setting process is performed to set the detection range of the first physical quantity in the first detection circuit. The first axis is the Z-axis, The first physical quantity is the Z-axis angular velocity, which is the angular velocity around the Z-axis. The second axis is the X-axis or the Y-axis, The inertial sensor is characterized in that the second physical quantity is either the X-axis acceleration, which is the acceleration in the X-axis direction, or the Y-axis acceleration, which is the acceleration in the Y-axis direction.

4. In the inertial sensor described in claim 3, The range setting unit is, An inertial sensor characterized by setting the detection range of the Z-axis angular velocity to be increased when the X-axis acceleration or the Y-axis acceleration exceeds a threshold.

5. A first sensor for detecting a first physical quantity in the first axis, A first detection circuit that performs detection processing of the first physical quantity based on the first sensor signal from the first sensor and outputs first detection information, A second sensor for detecting a second physical quantity in the second axis, A second detection circuit that performs detection processing of the second physical quantity based on the second sensor signal from the second sensor and outputs second detection information, A posture calculation unit that determines posture information of the object to be measured based on the first detection information and the second detection information, A range setting unit that performs range setting processing, Includes, The range setting unit is, An inertial sensor characterized by performing a range setting process to set the detection range of the first physical quantity in the first detection circuit based on the attitude information obtained by the attitude calculation unit.

6. In the inertial sensor described in claim 5, The first axis is the X-axis or the Y-axis, The first physical quantity is the X-axis angular velocity, which is the angular velocity around the X-axis, or the Y-axis angular velocity, which is the angular velocity around the Y-axis. The attitude calculation unit, The roll angle, which is the rotation angle around the X axis, or the pitch angle, which is the rotation angle around the Y axis, is determined as the attitude information. The range setting unit is, An inertial sensor characterized by setting the detection range of the X-axis angular velocity or the Y-axis angular velocity to be reduced when the roll angle or the pitch angle exceeds a threshold.

7. A first sensor for detecting a first physical quantity in the first axis, A first detection circuit that performs detection processing of the first physical quantity based on the first sensor signal from the first sensor and outputs first detection information, A second sensor for detecting a second physical quantity in the second axis, A second detection circuit that performs detection processing of the second physical quantity based on the second sensor signal from the second sensor and outputs second detection information, A range setting unit that performs range setting processing, Includes, The range setting unit is, Based on the first detection information and the second detection information, the range setting process is performed to set the detection range of the first physical quantity in the first detection circuit. The first axis is the X-axis or the Y-axis, The first physical quantity is the X-axis angular velocity, which is the angular velocity around the X-axis, or the Y-axis angular velocity, which is the angular velocity around the Y-axis. The second axis is the Z-axis, The second physical quantity is the Z-axis angular velocity, which is the angular velocity around the Z-axis. The range setting unit is, An inertial sensor characterized in that, in the initial setup, the detection range for the Z-axis angular velocity is set to a size less than or equal to the detection range for the X-axis angular velocity or the Y-axis angular velocity.

8. In an inertial sensor according to any one of claims 1 to 4, A third sensor for detecting a third physical quantity in the third axis, A third detection circuit that performs detection processing of the third physical quantity based on the third sensor signal from the third sensor and outputs third detection information, Includes, The range setting unit is, An inertial sensor characterized by performing a range setting process to set the detection range of the first physical quantity based on the first detection information, the second detection information, and the third detection information.

9. In the inertial sensor described in claim 8, Includes a posture calculation unit that determines posture information of the object to be measured based on the first detection information, the second detection information, and the third detection information. The range setting unit is, An inertial sensor characterized by performing the range setting process based on the attitude information obtained by the attitude calculation unit.

10. In an inertial sensor according to any one of claims 1 to 9, The range setting unit is, An inertial sensor characterized in that, when the first detection circuit is performing detection processing of the first physical quantity in the first detection range, and the detected value of the first detection information exceeds a first threshold within the first detection range, the detection range of the first physical quantity is set to a second detection range that is larger than the first detection range.

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