JPH11211480A - Attitude angle detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To moderate the limit of the place or environment for use to make a device widely usable by providing a specified HPF for processing the value of an A/D converter connected to the output part of a gyro. SOLUTION: A moving angle arithmetic device 17 finds the movement angle from the outputs of gyros 12a, 12b, 12c, and a static angle arithmetic device 24 finds the static angle from geomagnetic sensors 22a, 22b and acceleration sensors 23a, 23b. A judging device 32 judges whether the attitude angle includes an error or not, and an attitude angle arithmetic device 41 processes the signal from the judging device 32 or the like. An infinite length impulse response (IIR) HPF 14 processes the values of A/D converters 13a, 13b, 13c connected to respective output parts of the gyros 12a, 12b, 12c, and a positive and negative reversion judging device 15 judges whether the values from the A/D converters 13a, 13b, 13c are positive or negative. An IIR delay coefficient reset device 16 resets the IIR delay coefficient of the HPF 14 when the positive and negative signs of the positive and negative reversion judging device 15 is reversed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head mounted display (hereinafter, referred to as HMD) used for detecting and controlling the attitude of a moving object, virtual reality, and the like.
The present invention relates to a posture angle detection device suitable for use in detecting a posture angle (a rotation angle of three axes) of an object in a three-dimensional space, such as a tracker for detecting a head posture angle, a 3D game pad, and the like.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting head movement, which is used in virtual reality, a weak alternating magnetic field is generated from an externally installed alternating magnetic field source, and detected and controlled by a sensor unit arranged in an HMD. A method that uses an alternating magnetic field to detect head movement in the arithmetic unit, or an ultrasonic signal from an externally installed ultrasonic source is detected by the sensor unit located on the HMD, and the head operation is detected by the control arithmetic unit. There is a method using ultrasonic waves to be detected.

[0003]

However, in the former method using an alternating magnetic field, since the signal generating source is a weak alternating magnetic field, the responsiveness is reduced by using a large number of filters to cancel noise, and the head is reduced. Compared to the movement of
In some cases, the motion of the image of the HMD was slowed down, resulting in sickness and sickness.

In the latter method using ultrasonic waves,
Signals may not be detected due to malfunctions due to the effects of various other ultrasonic signals or obstacles between the signal source and the sensor.Received only with the arm or hair in front of the sensor There has been a problem that it becomes impossible and malfunctions.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, to alleviate restrictions on the place and environment of use, and to provide a posture angle detecting device which can be used widely.

[0006]

According to the present invention, there are provided three gyros for detecting an X-axis and a Y-axis orthogonal to a horizontal plane and an angular velocity about a Z-axis orthogonal to each of the X-axis and the Y-axis; Based on the output according to the angular velocity of the motion angle calculation device that calculates the motion angle that is the angle moved per unit time, and arranged to detect at least two-axis acceleration orthogonal to each other at least in the XY plane, An acceleration sensor for detecting a roll angle which is a rotation angle around the X axis and a pitch angle which is a rotation angle around the Y axis; a geomagnetic sensor arranged to detect at least the two axes of geomagnetism; A static angle computing device that computes a roll angle, a pitch angle and a yaw angle that is a rotation angle around the Z axis based on the outputs of the acceleration sensor and the geomagnetic sensor, and computes the truth or false of the computation result by the static angle computing device Discriminator And an attitude angle calculation device that calculates an attitude angle output from the calculation result of the motion angle calculation device according to the calculation result of the discriminating device. A / D converters connected to each other, and an IIR (infinite impulse resres) for high-pass filtering the value of the A / D converter
ponse: infinite-length impulse response) type digital high-pass filter, positive / negative inversion determining device for determining whether the value from the A / D converter is positive or negative on the basis of a reference value, and IIR for resetting an IIR delay coefficient of the high-pass filter An attitude angle detection device comprising a delay coefficient reset device, wherein the IIR delay coefficient reset device resets the IIR coefficient of the high-pass filter when the sign of the sign determination device is reversed.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an HMD to which an attitude angle detecting device is applied.
This HMD is provided so that the image displayed on the display in front of the HMD changes in conjunction with the movement of the user's head and allows the user to experience a virtual space. If you turn to the right while holding it, the head posture angle measured by the posture angle detection device is transmitted to the video generation device, and the video generation device transmits the video corresponding to the posture angle to the HMD, so the video developed to the right Is displayed so that a 360-degree image of the entire space can be realized by the movement of the head.

As shown in FIG. 1, reference numeral 1 denotes an HMD main body, in which an attitude angle detecting device 2 according to the present invention is arranged, and a video signal generating device 7 is connected by a signal cable 4.
It is connected to the.

FIG. 2 is a block diagram showing the overall configuration of the attitude angle conversion device according to the present invention. As shown in FIG.
Motion angle detecting means 11 having a motion angle calculating device 17 for calculating and calculating a motion angle (movement angle) per unit time from the outputs of the three gyros, and stopping from two geomagnetic sensors and two acceleration sensors A static angle detecting means 21 provided with a static angle calculating device 24 for calculating an angle; and whether or not an error is included in the attitude angle calculated by the static angle detecting means 21 (for example, when a linear acceleration is applied, A determination device 32 for determining whether the acceleration sensor includes a signal other than the inclination);
It comprises a motion angle computing device 17, a stationary angle computing device 24, and an attitude angle computing device 42 that processes signals from the discriminating device 32.

FIG. 3 is an explanatory view showing the arrangement of a gyro, an acceleration sensor, and a geomagnetic sensor in the attitude angle detecting device of the present invention. As shown in FIG. 3, three axes orthogonal to each other (an axis orthogonal to the horizontal plane is an X axis, a Y axis, an axis orthogonal to each of the X axis and the Y axis is a Z axis, a rotation angle around the X axis is a roll angle, The first gyro 12a, the second gyro 12b, and the third gyro 12c for detecting the angular velocity around the Y axis are referred to as a pitch angle, and the rotation angle about the Z axis are referred to as a yaw angle. , X, Y, and Z axes are arranged in parallel to each other, that is, orthogonal to each other. First geomagnetic sensor 22a and second geomagnetic sensor 22b for detecting yaw angle
Is composed of two axes (here, X axis and Y axis) orthogonal to each other on a horizontal plane. Similarly, the first acceleration sensor 23a and the second acceleration sensor 23b are arranged on two axes (here, the X axis and the Y axis) orthogonal to each other on a horizontal plane. Gyro is a piezoelectric ceramic, piezoelectric single crystal,
Alternatively, a vibrator made of a nonmagnetic material such as silicon can be used. In the present embodiment, a piezoelectric vibrating ceramic gyro manufactured by Tokin Co., Ltd. was used.

As shown in FIG. 2, the output units of the three-axis gyros 12a, 12b, 12c have A /
The D converters 13a, 13b, 13c, and the IIR digital high-pass filter 14 are connected, and an output unit of the high-pass filter 14 is connected to a motion angle calculation device 17 that calculates an angle moved from a value passed through the high-pass filter. Further, an IIR coefficient reset device 16 for resetting an IIR delay coefficient of the high-pass filter 14 and a positive / negative inversion for judging whether a value from the A / D converters 13a, 13b, 13c is positive or negative at a certain reference value (zero point). A determination device 15. The high-pass filter 14 resets the IIR coefficient when the polarity of the positive / negative reversal determination device is reversed, and has an adverse effect (return voltage) due to the conventional high-pass filter.
, The offset voltage of the gyro is canceled, and at the same time, adverse effects are eliminated, and high accuracy is obtained.

FIG. 4 shows a posture angle detecting device according to the present invention.
FIG. 3 is a block diagram of a static angle calculation device. As shown in FIG. 4, a roll angle calculating means for calculating a roll angle R (n) and a pitch angle P (n) from the outputs Ax (n) and Ay (n) of the acceleration sensor, a pitch angle calculating means, A backup memory for storing the yaw angle calculation result Φ (n-1), and a north component 傾斜_{2 of the} inclination angle based on the outputs Ax and Ay of the acceleration sensor and the contents Φ (n-1) of the backup memory.
, A geomagnetic Mz sign determining means for determining the sign of the geomagnetic Z-direction component Mz, a geomagnetic Mz absolute value calculating means, a geomagnetic Mz sign determining means, and a geomagnetic Mz absolute value calculating means. Means for calculating a geomagnetic Z-axis component Mz from the means, and a measured or obtained geomagnetic X-axis component Mx, a Y-axis component My, and a horizontal coordinate axis Hx from the measured or determined geomagnetic component Mz in the sensor coordinate system. It is composed of coordinate transformation calculating means for performing conversion to Hy and Hz, and azimuth calculating means for calculating the azimuth based on Hx and Hy. By calculating the geomagnetic Z-axis direction component Mz virtually by the geomagnetic Mz calculating means. The yaw angle is detected only by a biaxial geomagnetic sensor.

Further, as shown in FIG. 4, in the northern component tilt angle calculating device and the geomagnetic Mz code discriminating means, the northward component tilt angle θ ₂ , the dip angle θ ₀ of the geomagnetism at the origin, and the output of the backup memory are Φ. (N-1), assuming that the outputs of the two axes of the acceleration sensor are Ax and Ay, respectively, θ ₂ = sin ^-1 [Ax (n) · cosΦ (n-1) + Ay (n) · sinΦ (n-1)] If −90 degrees ≦ θ ₂ ≦ θ ₀ , the geomagnetic Mz code is determined to be negative, and if θ ₀ <θ ₂ ≦ 90 degrees, the geomagnetic Mz code is determined to be positive.

More specifically, when the moving body rotates in a horizontal plane (that is, the XY plane), the azimuth angle Φ (n) is determined by the outputs Mx (n) and My (n) from the geomagnetic sensor. ) = Tan ^-1 [Mx (n) / My (n)] (1) If the azimuth at the origin is Φ ₀ , the azimuth angle Y
(N) is as follows: Y (n) = Φ (n) −Φ ₀ (2)

However, when the moving object has a roll angle or a pitch angle and is not horizontal, coordinate conversion is performed using the roll angle and the pitch angle, and the geomagnetism in absolute coordinates is calculated as Mx (n),
Find My (n) and apply equations (1) and (2). At that time, a Z-axis direction component Mz (n) of the geomagnetism is required.

The method of calculating the geomagnetic Z-direction component Mz (n) is as follows.
First, in order to determine the sign, a north component (north pitch angle) θ ₂ is determined using Φ (n−1). ^{_{θ 2 = sin -1 [Ax (}} n) · cosΦ (n-1) + Ay (n) · sinΦ (n-1)] placed seeking dip theta ₀ in advance geomagnetism at the theta ₂ and the origin, comparing . θ ₀ = tan ⁻¹ [Mz (0) / (Mx (0) ² + My (0) ² ) ^1/2 ] If −90 degrees ≦ θ ₂ ≦ θ ₀ , the sign of Mz is minus, If θ ₀ <θ ₂ ≦ 90 degrees, the sign of Mz is plus. Next, if the geomagnetism Ht is known, the absolute value of Mz can be obtained by Expression 1.

[0018]

(Equation 1)

The geomagnetism Ht is obtained by the following procedure. First, the sensor unit is tilted by 90 degrees so that the magnetic sensor 1 or the magnetic sensor 2 faces the Z axis. Then, a signal is sent, for example, a key or button is pressed, and the value of the sensor facing the Z axis at that time is stored in the memory as Mz (0). Next, return the sensor unit to the origin position, send some signal again, and
The values of (n) and My (n) are stored in the memory as Mx (0) and My (0). These Mx (0), My (0),
Ht is given by Equation 2 using Mz (0).

[0020]

(Equation 2)

Next, a description will be given of a discrimination device among the posture angle detection devices of the present invention. The discriminating device for judging whether or not the temporary attitude angle obtained by the stationary angle detecting means including the two-axis acceleration sensor and the two-axis geomagnetic sensor is correct is as follows.

That is, the acceleration Ax (n) in the X-axis direction and the acceleration A in the Y-axis direction obtained from the outputs of the two-axis acceleration sensor
From y (n), roll angle R (n) and pitch angle P (n)
Is obtained from the following equation.

R (n) = sin ⁻¹ [Ax (n) / cosP (n)] P (n) = sin ⁻¹ Ay (n)

Here, Ax (n) and Ay (n) are composite vectors of the gravitational acceleration and the X and Y axis components of the inclination angular velocity.
It does not become pitch angle. Then, from R (n) to R (n−
1) minus 0 is near 0, or P (n)
If P (n-1) is close to 0, it is determined that there is no motion acceleration, that is, R (n) and P (n) are correct. Otherwise, it is determined that there is a motion acceleration. That is, when at least one of Expression 3 and Expression 4 is substantially zero, it is determined that the posture angle information from the stationary angle detection unit is correct.

[0025]

(Equation 3)

[0026]

(Equation 4)

On the basis of the determination result obtained from the two-axis acceleration sensor, the attitude angle calculating device calculates the attitude angle according to the present invention from the motion angle and the static angle obtained from the motion angle detecting means and the static angle detecting means. The attitude angle to be determined by the detection device is calculated.

Next, among the attitude angle detecting devices of the present invention, an attitude angle calculating device will be described. The outputs to be obtained by the attitude angle detecting device of the present invention are α (n), β (n), γ (n), and the motion angles obtained from the dynamic motion angle detecting means are {X (n), △
Assuming that Y (n), △ Z (n), and the static angles determined by the static static angle detection means are R (n), P (n), and Φ (n), the attitude angle information from the static angle detection means Is determined to be correct, α (n) = α (n−1) + ΔX (n) −Cβ (n) = β (n−1) + ΔY (n) −Cγ (n) = γ (n−1) + △ Z (n) −C where C is a constant not larger than the arbitrarily selected error, and the sign is plus when the sign of the error is plus;
When minus, minus.

When it is determined that the posture angle information from the stationary angle detecting means is wrong, α (n) = α (n−1) + △ X (n) β (n) = β (n−1) + ΔY (n) γ (n) = γ (n−1) + ΔZ (n) The attitude angle is calculated and obtained.

As another embodiment of the present invention, when it is determined that the attitude angle information from the static angle detecting means is correct, α (n) = α (n−1) + △ X (n) −k [Α (n-1) + △ X
(n) −R (n)] β (n) = β (n−1) + △ Y (n) −k [β (n−1) + △ Y
(n) −P (n)] γ (n) = γ (n−1) + ΔZ (n) −k [γ (n−1) + ΔZ
(n) −Φ (n)]. Here, k is a proportional constant of 1 or less that is arbitrarily selected.

When it is determined that the posture angle information from the stationary angle detecting means is wrong, α (n) = α (n−1) + △ X (n) β (n) = β (n−1) + ΔY (n) γ (n) = γ (n−1) + ΔZ (n) The attitude angle is calculated and obtained.

Therefore, when the attitude angle detecting device of the present invention is applied to the HMD as in the present embodiment, it is possible to obtain angle information without a cumulative error at a high speed without using an external signal, and to obtain a high angle information. Performance.

By inserting a high-pass filter in the output section of the gyro, the influence of drift can be eliminated, but the signal is also affected and the output is not correct [FIG. 5 (c)]. This is due to the return voltage of the capacitor, and is particularly noticeable when only positive or only negative output continues. As in the present invention, an A / D converter connected to each of the output sections of the gyro and this A / D converter
IIR that high-pass filters the value of the / D converter
Type digital high-pass filter, a positive / negative inversion determining device for determining whether the value from the A / D converter is positive or negative based on a reference value, and an IIR delay coefficient reset device for resetting an IIR delay coefficient of the high-pass filter. , This effect can be eliminated. In the output of the filter, the process of resetting the buffer when the polarity is inverted reverses the return voltage, and a correct output is obtained [FIG. 5 (d)].

In the attitude angle detecting device according to the present invention, since the gyro is mounted as an element, it is possible to reduce the size and weight, and since the ceramic vibrator is used, no magnetic noise is received, and the magnetic sensor is not received. Even if they are close to each other, the function is not impaired. By using an IIR digital high-pass filter, high precision can be achieved.

In this embodiment, a geomagnetic sensor,
Although two acceleration sensors have been described as examples, at least one of them may be three. This embodiment is most preferable in terms of miniaturization.

[0036]

According to the present invention, it is possible to provide a posture angle detecting device that can be used widely by alleviating restrictions on the place and environment of use.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a usage state of a posture angle detection device in an HMD of the present invention.

FIG. 2 is a block diagram showing the overall configuration of the attitude angle conversion device of the present invention.

FIG. 3 is an explanatory diagram showing an arrangement of a gyro, an acceleration sensor, and a geomagnetic sensor in the attitude angle detecting device of the present invention.

FIG. 4 is a block diagram showing a configuration of a static angle calculation device in the attitude angle detection device of the present invention.

FIG. 5 is a diagram showing an output waveform of a motion angle. FIG. 5A is a diagram illustrating an input waveform of a gyro. FIG. 5B is a diagram illustrating an output waveform of the gyro. FIG. 5C is a diagram illustrating an output waveform of the high-pass filter. FIG. 5D is a diagram illustrating an output waveform of an IIR digital high-pass filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 HMD main body 2 Attitude angle detection device 4 Signal cable 7 Image generation device 11 Motion angle detection means 12a First gyro 12b Second gyro 12c Third gyro 13a (First) A / D converter 13b (Second ) A / D converter 13c (Third) A / D converter 14 (IIR digital) high-pass filter 15 Positive / negative inversion determining device 16 IIR coefficient reset device 17 Motion angle computing device 21 Static angle detecting means 22a First geomagnetic sensor 22b Second geomagnetic sensor 23a First acceleration sensor 23b Second acceleration sensor 24 Static angle calculation device 32 Discrimination device 42 Attitude angle calculation device

Claims (1)

[Claims] 1. An X-axis and a Y-axis orthogonal to each other in a horizontal plane, and
Three gyros for detecting angular velocities around a Z-axis orthogonal to each of the axis and the Y-axis, and a motion angle for calculating a motion angle, which is an angle moved per unit time, based on an output corresponding to the angular velocity of the gyro. An arithmetic unit and arranged to detect accelerations of two axes orthogonal to each other at least in an XY plane;
An acceleration sensor for detecting a roll angle which is a rotation angle around the X axis and a pitch angle which is a rotation angle around the Y axis; a geomagnetic sensor arranged to detect at least the two axes of geomagnetism; A static angle computing device that computes a roll angle, a pitch angle and a yaw angle that is a rotation angle around the Z-axis based on the outputs of the acceleration sensor and the geomagnetic sensor, and computes whether the computation result by the static angle computing device is true or false A discriminating device for
And a posture angle calculation device that calculates a posture angle output from the calculation result of the motion angle calculation device in accordance with the calculation result of the discriminating device. A / D converter connected and II for high-pass filtering the value of the A / D converter
An R-type digital high-pass filter, a positive / negative inversion determining device for determining whether the value from the A / D converter is positive or negative on the basis of a reference value, and an IIR delay coefficient reset device for resetting an IIR delay coefficient of the high-pass filter. Prepared,
An attitude angle detecting device, wherein the IIR coefficient of the high-pass filter is reset by an IIR delay coefficient reset device when the sign of the sign determining device is reversed.