JP2003106840A - Rotary angle detector, voice reproducer and head- mounted display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a rotary angle from the output of an angular velocity sensor. SOLUTION: A low-pass filter 22 takes out the necessary component of a band from the output of the angular velocity sensor 10. The output signal Do of the filter 22 is supplied to a low-pass filter 31, which detects a low-frequency component and supplies its output to a rotary deciding unit 32, which decides whether an element 1 to be detected is rotated or not. When the element 1 is stopped, the low-frequency component of the output of the filter 31 is written as an offset value in a ring buffer 34. When the element 1 is rotated, the writing of the low-frequency component of the output of the filter 31 in the buffer 34 is stopped, and the offset values of a plurality of samples written in the buffer 34 are read. The mean value of the offset values of the plurality of the samples is calculated, its calculated result Ds is subtracted from the signal Do, and the subtracted result Dv is integrated by an integrating circuit 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device using an angular velocity sensor for detecting a rotation angular velocity of a detection object, and an electronic device such as a voice reproducing device or a head mounted display device having the rotation angle detecting device. Regarding equipment.

[0002]

2. Description of the Related Art Integrating an angular velocity detection signal output from an angular velocity sensor to detect a rotation angle (rotation angle) of an object to be detected has been performed and considered in various fields.

For example, by attaching an angular velocity sensor to the headphones, detecting the rotation of the listener's head wearing the headphones, and processing the audio signal according to the detection result, even if the listener faces left and right, It is considered that the sound image of the audio signal is localized at an arbitrary fixed position outside the listener's head so that a sound field equivalent to that when a speaker is arranged at that position can be obtained.

In the car navigation system,
The correct traveling direction is calculated by detecting a change in the traveling direction of the vehicle, and the GPS (Global) is used to know the position by using this and the output of the vehicle speed sensor.
(Positioning System) is used together to calculate the current position.

However, the angular velocity detection signal output from the angular velocity sensor includes a component having a very low frequency close to DC as an offset component, and the level of the offset component varies from one angular velocity sensor to another. Fluctuates due to changes in environment such as temperature.

Therefore, if the angular velocity detection signal output from the angular velocity sensor is integrated as it is to detect the rotation angle, it will be detected as being rotating even when the object to be detected is stationary, and the object to be detected will be detected. Even when the body is rotating, its rotation angle cannot be accurately detected. Therefore, it is necessary to remove this offset component from the angular velocity detection signal output from the angular velocity sensor.

FIG. 6 shows a conventional rotation angle detecting device for removing this offset component. With this rotation angle detection device,
The output signal of the angular velocity sensor 10 is the A / D converter 21.
Is converted into digital data by the low-pass filter 22.
Taken out through. The low-pass filter 22 extracts a component in a required band from the output signal of the angular velocity sensor 10, and its cutoff frequency is, for example, 100 Hz.
It is said that

The angular velocity detection signal Do extracted from the low-pass filter 22 is supplied to the high-pass filter 101, and the low frequency component which is the offset component is removed. The cutoff frequency of the high pass filter 101 is, for example, 0.01 Hz.

However, when the angular velocity detection signal Do is taken out through the high-pass filter 101 in order to remove the offset component, the backlash B is added to the angular velocity detection signal Dp output from the high-pass filter 101 as shown in FIG.
Occurs, and when this is integrated by the integrating circuit 103, a large error occurs.

Therefore, the angular velocity detection signal Dp output from the high-pass filter 101 is supplied to the low level removing circuit 102, and the low level signal indicated by the level range L in FIG. 7 in the angular velocity detection signal Dp is removed. The angular velocity detection signal Dq after removal is integrated by the integration circuit 103.

[0011]

However, in the conventional rotation angle detection device of FIG. 6, since the high-pass filter 101 removes the offset component from the original angular velocity detection signal Do, the angular velocity detection signal after the offset component is removed. A backlash B is generated in Dp, and in order to remove the backlash B, the low-level removal circuit 102 removes the low-level signal in the angular velocity detection signal Dp after the offset component is removed, so that the angular velocity detection which is not the offset component is performed. Some components are also lost, and the rotation angle cannot be detected with high accuracy.

The time constant of the high pass filter 101 is increased to suppress the backlash B, and the low level removing circuit 102
It is also possible to integrate the angular velocity detection signal Dp of the output of the high-pass filter 101 as it is in the integrating circuit 103 without removing the low level signal. However, in that case, it takes time for the high-pass filter 101 to reach a steady state, and during that time, the offset component cannot be removed and the rotation angle cannot be detected.

Therefore, the present invention is directed to a rotation angle detecting device using an angular velocity sensor, which is capable of detecting the rotation angle with high accuracy.

[0014]

A rotation angle detecting device of the present invention is a low-pass filter for detecting a low frequency component from an output signal of an angular velocity sensor for detecting a rotation angular velocity of an object to be detected, and the detected low frequency filter. The component is a storage unit in which a plurality of samples are written as an offset value, a rotation determination unit that determines whether the detected object is rotating from the output signal of the angular velocity sensor, and the rotation determination unit When it is determined that the detected object is not rotating, the low-frequency component detected by the low-pass filter is written in the storage unit as an offset value, and the detected object is rotating by the rotation determination unit. When it is determined, the control unit that stops the writing of the low frequency component to the storage unit and reads the offset values for a plurality of samples from the storage unit. An arithmetic unit that calculates an average value of offset values for a plurality of samples read from the storage unit, subtracts the calculation result from the output signal of the angular velocity sensor, and integrates the subtraction result. .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment of Rotation Angle Detection Device ... FIGS. 1 and 2] FIG. 1 shows an embodiment of a rotation angle detection device of the present invention.

An angular velocity sensor 10 such as a piezoelectric vibrating gyro that detects the angular velocity of rotation is attached to the object to be detected 1. The angular velocity detection signal output from the angular velocity sensor 10 includes a component having a very low frequency close to direct current as an offset component, and the level of the offset component varies from one angular velocity sensor to another, the temperature, etc. It fluctuates due to changes in the environment.

The output signal of the angular velocity sensor 10 is A /
It is converted into digital data by the D converter 21 and taken out through the low pass filter 22. Low pass filter 2
Reference numeral 2 is for extracting a component in a required band from the output signal of the angular velocity sensor 10, and its cutoff frequency is, for example, 100 Hz.

The angular velocity detection signal Do extracted from the low pass filter 22 is supplied to the low pass filter 31 in the offset detecting section 30 to detect a low frequency component. The cutoff frequency of the low-pass filter 31 is selected within the range of 0.125 Hz to 0.002 Hz, for example.

At the same time, the angular velocity detection signal Do extracted from the low-pass filter 22 is supplied to the rotation determination unit 32 in the offset detection unit 30, and the rotation determination unit 32 determines the degree of change in the angular velocity detection signal Do from the detected value. Detecting body 1
It is determined whether or not is rotating.

Specifically, in the rotation determination section 32, for each sample of the angular velocity detection signal Do which is digital data,
The sample value is compared with the immediately preceding sample value, and when the change between the two is within a predetermined threshold value, the detected object 1
The rotation determination unit 32 is configured to determine that the detection target 1 is rotating when it is determined that the detection target 1 is stationary and the change between the two exceeds a predetermined threshold value.

The determination result of the rotation determination unit 32 is supplied to the buffer control unit 33, and when the rotation determination unit 32 determines that the object to be detected 1 is stationary, the buffer control unit 33 low-passes at that time. The low frequency component detected by the filter 31 is written in the ring buffer 34 as an offset value.

For example, as shown in FIG. 2, the ring buffer 34 can write a maximum of 16 samples of offset values. When 16 samples are written, the oldest ones are erased and the newest ones are erased. Configure to be written.

In the buffer control unit 33, the rotation determination unit 32
When it is determined that the detected object 1 is rotating, the writing of the low-frequency component detected by the low-pass filter 31 to the ring buffer 34 at that time is stopped, and the low-frequency component is written to the ring buffer 34. The offset value for a maximum of 16 samples is read.

Then, the averaging processing unit 35 calculates the average value of the offset values of up to 16 samples read from the ring buffer 34, and the adding circuit 40 calculates the calculation result of the averaging processing unit 35. The signal Ds is transferred to the signal detector 2
An offset component in the angular velocity detection signal Do from the low pass filter 22 of 0 is subtracted from the angular velocity detection signal Do, and the subtraction result signal Dv is integrated by the integration circuit 51 as the angular velocity detection signal after the offset component is removed.

The low-frequency component detected by the low-pass filter 31 when the object to be detected 1 is stationary is the output of the angular velocity sensor 10 regardless of variations among the angular velocity sensors and changes in environment such as temperature. Angular velocity detection signal D
While it is equal to the offset component in o, the detected object 1
The low-frequency component detected by the low-pass filter 31 when is rotating includes the angular velocity detection component and does not match the offset component.

In the above-described rotation angle detecting device, only the low frequency component equal to the offset component when the detected body 1 is stationary is written in the ring buffer 34, and when the detected body 1 is rotating. , The low-frequency component when the detected object 1 immediately before is stationary is read from the ring buffer 34, and the average value thereof is subtracted from the angular velocity detection signal Do output from the angular velocity sensor 10, so that the offset component is ensured. And it can be removed accurately and the rotation angle can be detected with high accuracy.

The time constant of the low-pass filter 31 can be changed by the control signal Sc, and the time constant is set at the time of starting the operation of the electronic equipment including the detected object 1 and provided with the rotation angle detecting device, such as when the power is turned on. Decrease the constant and then gradually increase the time constant.

Thus, when the operation of the electronic device is started, the low-pass filter 31 can be converged to a stable state in a short time, and highly accurate detection of the rotation angle can be started in a short time.

In the output processing section 50, the rotation angle detection signal output from the integration circuit 51 is supplied to the azimuth conversion section 52 as necessary to determine the rotation direction and the rotation angle of the detected object 1 with respect to the reference azimuth. The direction of the detected object 1 is detected.

[Embodiment of Audio Reproducing Device ... FIGS. 3 and 4] The rotation angle detecting device of the present invention, for example, listens to audio by headphones and localizes a sound image at an arbitrary fixed position outside the listener's head. It can be used for an audio reproducing device.

FIG. 3 shows the principle thereof, in which the listener 3 wears the headphones 5 and listens to the sound with the left and right acoustic transducers 5L and 5R. Is localized at a position indicated by the sound source 7 on the median surface in front of the listener, and a sound field equivalent to that when a speaker is arranged at that position is obtained. In this case, the transfer functions from the sound source 7 to the left ear 3L and the right ear 3R of the listener 3 are HL and HR.

FIG. 4 shows an embodiment of the audio reproducing apparatus of the present invention in this case. An angular velocity sensor 10 is attached to the headphones 5, and the output signal of the angular velocity sensor 10 has the configuration shown in FIG. The rotation angle detection device 60 is supplied to detect the rotation of the listener's head wearing the headphones 5.

In this case, from the output processing unit 50 of the rotation angle detection device 60, the azimuth (direction) θ of the listener's head at that time is given.
The rotation direction and rotation angle of the sound source 7 from the azimuth θ0 in FIG. 3 are detected.

In this embodiment, the transfer function HL (θ from the sound source 7 of FIG. 3 to the left ear 3L of the listener 3 when the heading θ of the listener is θ0, θ1, θ2, ...
0), HL (θ1), HL (θ2), ... HL (θn)
And a transfer function H from the sound source 7 to the right ear 3R of the listener 3.
R (θ0), HR (θ1), HR (θ2), ... HR
Digital filters 71-0, 71-1, 71-2, ... 71-n for convolving the impulse response corresponding to (θn)
, 72-0, 72-1, 72-2, ... 72-n, and the input digital audio signal Di is fed to the digital filters 71-0, 71-1, 71-2 ,.
2-0, 72-1, 72-2, ... 72-n. θ1, θ2, ... θn are set at equal angular intervals in the clockwise direction and the counterclockwise direction from the azimuth of θ0.

Then, by the selector 73L, the digital filters 71-0, 71-1, 71-2, ... 71-
Of the n, the output signal of the filter corresponding to the azimuth closest to the azimuth θ of the listener's head at that time, which is indicated by the detection signal from the rotation angle detection device 60, is output to the acoustic transducer 5L on the left side of the headphones 5. It is taken out as an audio signal to be supplied, and selected by the selector 73R among the digital filters 72-0, 72-1, 72-2, ... 72-n, which is indicated by the detection signal from the rotation angle detection device 60. The output signal of the filter corresponding to the azimuth closest to the azimuth θ of the listener's head at this time is extracted as an audio signal to be supplied to the acoustic transducer 5R on the right side of the headphones 5.

The digital audio signals output from the selectors 73L and 73R are D / A converters 74L and 74R.
Is converted into an analog audio signal by, and the two systems of analog audio signals are amplified by the audio amplifier circuits 75L and 75R and supplied to the left and right acoustic transducers 5L and 5R of the headphone 5.

In this case, at the time of starting the operation of the sound reproducing device such as when the power is turned on, until the low frequency component is detected by the low pass filter 31 shown in FIG. An accurate detection signal cannot be obtained from 60, and the sound image of the audio signal Di cannot be localized at a desired position.

Therefore, the control signal Sc controls the audio amplifying circuits 75L and 75R so that the low frequency component is detected by the low-pass filter 31 shown in FIG. 1 of the rotation angle detecting device 60 when the operation of the audio reproducing device is started. Until that time, the audio output is silenced.

[Embodiment of Head-Mounted Display Device ... FIG. 5] A rotation angle detection device of the present invention is, for example, a head-mounted display device, so-called HMD (Head M).
It can be used for the mounted display).

FIG. 5 shows an embodiment of the head-mounted display device of the present invention. The head-mounted part 81 of the head-mounted display device includes a body part 82 located in front of the eyes of the user 9 and an arm part 83L for putting the body part 82 on the ears of the user 9.
And 83R, the main body 82 is provided with image display portions 85L and 85R such as a liquid crystal panel.

The angular velocity sensor 10 is attached to the head mounting portion 81, the rotation angle detecting device 60 having the configuration shown in FIG. 1 is provided, and the rotation of the head of the user wearing the head mounting portion 81 is detected.

In this case, from the output processing unit 50 of the rotation angle detecting device 60, the azimuth (orientation) of the user's head at that time.
In FIG. 5, the rotation direction and the rotation angle from the azimuth in front of the user 9 are detected.

On the other hand, the digital video signals SL and SR obtained at the input terminals 91L and 91R are transferred to the video processing unit 9
Supply to 2L and 92R.

The video processing units 92L and 92R are provided with an image memory, and control the writing of the video signals SL and SR to the image memory and the reading from the image memory by the detection signal from the rotation angle detecting device 60. As described later, the image display unit 8 of the head mounting unit 81.
The images displayed on 5L and 85R can be moved in the left-right direction on the respective display screens 86L and 86R.

The video signals from the video processing units 92L and 92R are converted into analog video signals by the D / A converters 93L and 93R, and the analog video signals are supplied to the display drive units 94L and 94R, and the display drive unit 94L. And 94R drive the image display portions 85L and 85R.

When the user 9 turns to the left from the state of facing the front as shown in FIG. 5, the image display sections 85L and 85L are processed by the image processing sections 92L and 92R.
On the display screens 86L and 86R of the 5R, the images are displayed at the positions moved to the right in accordance with the rotation angle of the user's head, and conversely, the user 9 turns the front as shown in FIG. When facing the right direction from the facing state, by the processing in the image processing units 92L and 92R, the image is moved to the left side according to the rotation angle of the user's head on the display screens 86L and 86R of the image display units 85L and 85R. Images should be displayed at the moved positions.

As a result, the user 9 has the image display unit 8
With the head mounting portion 81 provided with 5L and 85R mounted, even when facing the left and right directions, the image can be viewed as if the image is displayed at a fixed position on the front.

In this case, when the head-mounted display device starts operating, such as when the power is turned on, until the low-frequency component is detected by the low-pass filter 31 shown in FIG. An accurate detection signal cannot be obtained from the angle detection device 60, and the virtual image display position cannot be set at the desired position.

Therefore, by controlling the image processing units 92L and 92R by the control signal Sc, when the head mounted display device starts to operate, the low frequency component of the rotation angle detection device 60 shown in FIG. Until it is detected, the display screens 86L and 86R are made to stand still without moving the video display position or the display screen 86L.
And a warning is displayed on 86R indicating that the operation is in an unstable state.

By combining the head-mounted display device according to this embodiment with the audio reproducing device according to the embodiment shown in FIG. 4, even if the viewer turns to the left and right, a constant position of the viewing environment is always maintained. It is possible to construct a video / audio reproduction system in which a video can be viewed as if it is being displayed on the screen, and a sound image is localized at a fixed position in the viewing environment.

[0051]

As described above, according to the present invention, the rotation angle detecting device using the angular velocity sensor can detect the rotation angle with high accuracy.

Further, the time constant of the low-pass filter for detecting the low frequency component is made relatively small at the start of the operation of the device, and then made relatively large, so that the low-pass filter can be made in a short time at the start of the operation of the device. The filter can be converged to a stable state, and highly accurate detection of the rotation angle can be started in a short time.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a rotation angle detection device of the present invention.

FIG. 2 is a diagram showing a part of the rotation angle detection device of FIG.

FIG. 3 is a diagram for explaining a case where a sound image is localized at a position outside the listener's head.

FIG. 4 is a diagram showing an embodiment of a sound reproducing device of the present invention.

FIG. 5 is a diagram showing an embodiment of a head-mounted display device of the present invention.

FIG. 6 is a diagram showing a conventional rotation angle detection device.

FIG. 7 is a diagram for explaining the rotation angle detection device of FIG.

[Explanation of reference numerals] Since all the main parts are described in the figure, they are omitted here.

Claims (7)

[Claims] 1. A low-pass filter for detecting a low-frequency component from an output signal of an angular velocity sensor for detecting a rotational angular velocity of an object to be detected, and the detected low-frequency component is written as an offset value for a plurality of samples. A storage unit, a rotation determination unit that determines whether or not the detected object is rotating from the output signal of the angular velocity sensor, and when the rotation determination unit determines that the detected object is not rotating. The low-frequency component detected by the low-pass filter is written in the storage unit as an offset value, and when the rotation determination unit determines that the detected object is rotating, the low-frequency component to the storage unit is low. Of the plurality of samples read from the storage unit, and a controller that reads the offset values of the plurality of samples from the storage unit. A rotation angle detection device comprising: an average value of the offset values of the above, a calculation unit that subtracts the calculation result from the output signal of the angular velocity sensor, and integrates the subtraction result. 2. The rotation angle detection device according to claim 1, wherein the time constant of the low-pass filter is relatively reduced at the start of operation of the device and then relatively increased. 3. A voice reproducing device comprising the rotation angle detecting device according to claim 1, wherein the angular velocity sensor is attached to headphones, and the voice signal is controlled by an output signal of the rotation angle detecting device. apparatus. 4. The audio reproducing device according to claim 3, wherein at the time of starting the operation of the device, until a low frequency component is detected by the low pass filter of the rotation angle detecting device,
An audio reproduction device in which the audio output is silent. 5. A head-mounted display device comprising the rotation angle detecting device according to claim 1, wherein the angular velocity sensor is attached to the head mounting portion, and an output signal of the rotation angle detecting device is provided. A head-mounted display device in which video display is controlled on a video display section provided in the head-mounted section. 6. The head-mounted display device according to claim 5, wherein at the time of starting the operation of the device, until a low-frequency component is detected by the low-pass filter of the rotation angle detection device,
A head-mounted display device in which a video display position is stationary on the video display unit or a warning is displayed on the video display unit. 7. An electronic device comprising the rotation angle detecting device according to claim 1.