JP2012052851A - Acceleration data correcting device and navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove any influence of vibration of a loud speaker from an output of an acceleration sensor in a system in which the acceleration sensor and the loud speaker are built into the same housing.SOLUTION: An electronic system (car navigation system) 10 in which a housing 100 is provided with a built-in loud speaker 132 and an acceleration sensor 124 has an acceleration data corrector 140 that removes the influence of vibration of the built-in loud speaker 132 on the output of the acceleration sensor 124. The acceleration data corrector 140 is provided with control means 110, an audio signal processor 141 that subjects audio signals supplied to the built-in loud speaker 132 to Fourier transform, an acceleration signal processor 142 that subjects the output of the acceleration sensor 124 to Fourier transform, and a signal synthesizer 143 that, when audio signals are outputted from the built-in loud speaker 132, subjects the output of the acceleration sensor, having also undergone Fourier transform, to inverse Fourier transform after clearing the output of any affected portion of the audio signals.

Description

  The present invention relates to an acceleration data correction device capable of removing the influence of vibration of a built-in speaker on the output of the acceleration sensor from the output of the acceleration sensor in an electronic device having a built-in speaker and an acceleration sensor in the housing, and The present invention relates to a navigation device.

  Conventionally, in a car navigation device, a GPS signal from a GPS satellite is received, a current position is calculated based on the information, and the calculated current position is displayed on a display screen provided in the car navigation device. By displaying it above, it is possible to identify where the user is now.

  Furthermore, the calculated current position data is compared with the road data stored in the map database. If the current position is not on the road data, the current position is matched on the appropriate road using various matching methods. The current position is displayed along with the map on the display screen.

  In order to accurately perform the matching process described above, or to detect the current position accurately even when the vehicle is traveling in a tunnel, a building or a mountain valley where GPS signals are difficult to reach, In many cases, an acceleration sensor or a gyro sensor is provided. The car navigation device can complement the current position data calculated based on the GPS signal using the output signals of the acceleration sensor and the gyro sensor, and detect a more accurate current position.

  Further, recent navigation devices are provided not only with a pure navigation function but also with various audio functions, and can reproduce sound from a speaker built in the car navigation device. For example, route guidance is performed on the display of the navigation device, and at the same time, music data recorded on a DVD or various recording media is reproduced, or terrestrial digital broadcasting is received and the sound is reproduced from a speaker. The speaker output is generally about 1 W.

  When sound reproduction is performed by the built-in speaker, the vibration of the speaker is transmitted to the housing of the car navigation apparatus, the vibration of the housing is detected by the acceleration sensor, and the sound output influence is mixed into the acceleration data (output of the acceleration sensor). If the influence of the vibration of the speaker on the output of the acceleration sensor is increased, the adverse effect on the current position detection and complementation in the car navigation device is also increased. In addition, the influence of the vibration of the speaker on the output of the acceleration sensor increases as the car navigation device housing becomes smaller.

  By the way, the following Patent Document 1 (Japanese Patent Laid-Open No. 2010-28674) discloses a “portable terminal” having a pedometer function for correcting an output from an acceleration sensor and obtaining an originally expected sensor output. . The portable terminal detects acceleration data when the user is walking or running while being held by the user. Regular vibrations should be detected as acceleration data when the user walks, but in practice, irregular vibrations are detected in part, so only the vibrations caused by the user's walking and running using the correction data. Is extracted.

JP 2010-28675 A

  In the invention of the portable terminal described in Patent Document 1, since it is assumed that the user's walking state is constant, the user's stride changes in the middle, the walking pace, etc. change. In such a case, the correction data cannot be applied, and it is impossible to accurately detect a change in vibration caused by the user's walking or running.

  By the way, the acceleration data detected in the car navigation device is not a constant period like the walking detection in the above-mentioned patent document, and includes more random elements based on acceleration / deceleration, ascent, descent, vibration, etc. of the automobile. It is out. In addition, the influence of vibration on the acceleration sensor that accompanies playback of music or music from the speaker does not occur intermittently as in the walking detection of the above-mentioned patent document, but occurs constantly during music playback. . Therefore, when the method of correcting the walking data in the walking detection of Patent Document 1 is applied to removing the influence of the vibration of the speaker from the acceleration data detected in the car navigation device, the vibration of the car is walking. Unlike the above-mentioned patent document 1, it is difficult to estimate and compensate for correct acceleration data, so that the influence of speaker vibration cannot be completely removed from the acceleration data. .

  In car navigation systems, the effect of speaker vibration on the acceleration sensor was corrected by passing the output of the acceleration sensor through a low-pass filter. However, the effect of speaker vibration could not be removed. .

  Therefore, an object of the present invention is to provide an acceleration data correction device capable of removing the influence of vibration of the speaker from the output of the acceleration sensor in an electronic device used by incorporating the acceleration sensor and the speaker in the same housing, and It is to provide a navigation device.

  In order to solve the above-described problems, an acceleration data correction apparatus according to the present invention eliminates the influence of vibration of the built-in speaker on the output of the acceleration sensor in an electronic device having a built-in speaker and an acceleration sensor in a housing. An acceleration data correction device, comprising: audio signal processing means for decomposing an audio signal supplied to the built-in speaker into frequency components; acceleration signal processing means for decomposing the output of the acceleration sensor into frequency components; and Signal synthesizing means for removing the audio signal decomposed into the frequency components from the output of the decomposed acceleration sensor.

  In one aspect of the acceleration data correction apparatus of the present invention, the acceleration data correction apparatus includes a frequency-amplitude table that represents the magnitude of the influence of vibration of the speaker based on the audio signal on the output of the acceleration sensor. The signal synthesizer refers to the frequency-amplitude table when removing the audio signal decomposed into the frequency components from the output of the acceleration sensor decomposed into the frequency components.

  Further, in one aspect of the acceleration data correction device of the present invention, the frequency-amplitude table includes the output of the acceleration sensor and the frequency component which are decomposed into the frequency components when the acceleration data correction device is stopped. It is created based on the audio signal decomposed into two.

  In the aspect of the acceleration data correction apparatus of the present invention, the signal synthesizing unit delays the audio signal decomposed into the frequency components by a time until vibration of the speaker affects the output of the acceleration sensor. And removing from the output of the acceleration sensor decomposed into the frequency components.

  Furthermore, the electronic device is a navigation device, and the navigation device includes the acceleration data correction device according to any one of claims 1 to 4.

  The present invention exhibits the excellent effects described below by having the above-described configuration. That is, an acceleration data correction device that removes the influence of vibration of the built-in speaker on the output of the acceleration sensor in an electronic device in which a housing includes a built-in speaker and an acceleration sensor, and is supplied to the built-in speaker Audio signal processing means for decomposing the audio signal into frequency components, acceleration signal processing means for decomposing the output of the acceleration sensor into frequency components, and the output of the acceleration sensor decomposed into frequency components into the frequency components. Further, it is possible to obtain a more accurate acceleration sensor output by providing the signal synthesis means for removing the voice signal.

  According to an aspect of the acceleration data correction apparatus of the present invention, the acceleration data correction apparatus includes a frequency-amplitude table that represents the magnitude of the influence of the vibration of the speaker based on the audio signal on the output of the acceleration sensor. Since the audio signal decomposed into the frequency components is removed with reference to the frequency-amplitude table, the audio signal components mixed in the acceleration sensor output can be more accurately removed.

  According to one aspect of the acceleration data correction apparatus of the present invention, the frequency-amplitude table is obtained by dividing the frequency sensor output into the frequency component and the frequency component when the acceleration data correction apparatus is stopped. It is preferable that the audio signal is generated based on the audio signal decomposed into two.

  According to one aspect of the acceleration data correction apparatus of the present invention, the influence of the audio signal is delayed from the output of the acceleration sensor by being delayed by the time that is output from the speaker and travels through the housing to reach the acceleration sensor. As a result, the audio signal can be removed from the acceleration sensor output in consideration of the time lag in which the vibration of the speaker is transmitted through the housing and mixed into the output of the acceleration sensor, thereby obtaining a more accurate acceleration sensor output. It becomes possible.

  Furthermore, according to the navigation device of the present invention, the sound output from the speaker built in the housing becomes a vibration and affects the output of the acceleration sensor, but the sound signal component mixed in the acceleration sensor output is removed. Therefore, a more accurate acceleration sensor output can be obtained. Accordingly, the current position can be detected more accurately, and the accuracy of route guidance can be improved.

FIG. 1 is an internal block diagram of the car navigation apparatus of this embodiment. FIG. 2 shows a frequency-amplitude table obtained by measuring how much acceleration data is detected as acceleration data in the acceleration sensor and decomposing for each frequency. FIG. 3 is a flowchart of a correction operation for removing the influence of speaker vibration from the measurement data of the acceleration sensor. FIG. 4 is a diagram schematically showing a state in which an audio signal component is removed from acceleration data that is Fourier-transformed together. FIG. 5 shows the acceleration data at a certain time among the Fourier-transformed acceleration data of FIG. 4A, and shows the actual acceleration component and the influence due to the audio signal. . FIG. 6 is a flowchart showing an operation for creating a frequency-amplitude table in the car navigation device 10 of the present embodiment.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described in detail below with reference to the drawings together with embodiments. However, in the following embodiments, a car navigation device in which the present apparatus is incorporated will be described as an acceleration data correction apparatus for embodying the technical idea of the present invention. The present invention is not intended to be specified as a car navigation device, and can be equally applied to other acceleration data correction devices without departing from the technical idea shown in the claims.

  The acceleration data correction device of the present invention can be used by electronically connecting a speaker and an acceleration sensor to an electronic device (hereinafter referred to as a car navigation device) in which the speaker and the acceleration sensor are built in the same casing. Alternatively, it can be used by being incorporated in a car navigation device. In this embodiment, a case where the acceleration data correction apparatus of the present invention is incorporated in a car navigation apparatus will be described.

  First, with reference to FIG. 1, the structure of each part of the car navigation apparatus 10 of a present Example is demonstrated. FIG. 1 is an internal block diagram of the car navigation apparatus 10 of the present embodiment. The car navigation apparatus 10 includes a casing 100 and a control unit 110 provided in the casing 100, a navigation unit 120, an audio visual unit 130, and an acceleration data correction unit 140.

  The housing 100 is a housing for housing various electronic components constituting the car navigation device 10. In particular, an acceleration sensor 124 and a speaker 132 described later are built in the housing 100. The casing 100 is installed at an appropriate location of the vehicle such as a dashboard of an automobile so that a driver or a user can use the car navigation device 10 by visually recognizing it.

  The control means 110 is composed of a CPU, a RAM, and a ROM (all not shown), and the control program stored in the RAM and ROM is executed by the CPU. Control and control the operations of the unit 120, the audio visual unit 130, and the acceleration data correction unit 140.

  The navigation unit 120 detects the current position of the vehicle on which the car navigation device 10 is mounted. The detected current position is displayed on a surrounding map displayed on the display unit 134 described later. The navigation unit 120 includes a current position detection unit 121, a map matching unit 125, and a map database 126.

  The current position detection unit 121 includes a GPS reception unit 122 and an autonomous navigation unit 123, and the autonomous navigation unit 123 further includes an acceleration sensor 124. The GPS receiver 122 calculates the current position (GPS positioning position) of the vehicle based on radio waves (GPS signals) including time information received from a plurality of GPS satellites orbiting the earth at predetermined time intervals. Based on the output from the acceleration sensor 124, the autonomous navigation unit 123 can supplement the current position calculated based on the GPS signal received by the GPS receiving unit 122. In addition, by providing the autonomous navigation unit 123, acceleration can be achieved even in a place where a GPS signal cannot be received, such as a tunnel, an underground mall, an underground parking lot, a parking lot in a building, or a place affected by multipath due to GPS signal reflection. The position of the car navigation device 10 (vehicle) can be calculated from the output from the sensor 124.

  The acceleration sensor 124 detects a change in acceleration applied in the three axis directions of the car navigation apparatus 10 and can calculate a moving distance in each axis direction by integrating the detected acceleration twice. However, as will be described later, the acceleration data detected by the acceleration sensor 124 includes a vibration caused by a speaker output, which will be described later, and the influence of the vibration.

  In addition, although the autonomous navigation part 123 demonstrated the structure provided only with the acceleration sensor 124 in a present Example, you may provide the gyro sensor (not shown). The gyro sensor can detect a change in angular velocity for detecting right or left turn or curve driving of the car navigation device 10 or a vehicle in which the gyro sensor is mounted, and complements the current position specified by the GPS signal, It is possible to accurately calculate the current position.

  The map matching unit 125 compares the current position detected by the GPS receiving unit 122 and supplemented by the autonomous navigation unit 123 with road data in the map database 126 described later, and is on the nearest road or until just before. The current position is set on an appropriate road with reference to the current position (which may include the traveling road and the traveling direction).

  The map database 126 holds map information composed of road data, building data, background data, and text data.

  The road data is composed of node data whose nodes are nodes such as inflection points and branch points of the road, and link data whose links are links between the nodes. The node data includes a node number, node position coordinates (latitude / longitude), node attributes such as intersection information and intersection name, the number of connection links, and connection link number data.

  The link data includes the node numbers that are the starting and ending points of the link, the first road type for distinguishing expressways, ordinary roads, streets, etc., and the first road for distinguishing the main line and connecting road of each road. 2 Road type, distance and / or required time, road name such as National Route ○, and data of traveling direction are configured. In addition to the above, link data includes data such as bridges, tunnels, railroad crossings, and tollgates as link attributes.

  The building data includes position coordinates (latitude / longitude) including at least three points of the building, types of buildings such as stations, buildings, and private houses, and display color data. Further, the background data is configured to include position coordinates (latitude / longitude) composed of at least three points serving as background image data such as a coastline, a lake, a river shape, a forest, and display color data.

  The text data includes characters (names) such as place names and river names, and data of their coordinates (latitude / longitude).

  The navigation unit 120 is a route search unit (not shown) that searches for a route from the current position or a specified departure point to a specified destination, or a route guide unit that performs route guidance according to the searched guide route and the current position. (Not shown) may be provided.

  The audio visual unit 130 includes an audio playback unit 131, a speaker 132, and a display input unit 133. The audio playback unit 131 includes a reading unit, a decoder, an amplifier (none of which are shown) corresponding to various recording media such as an SD card, and reads audio signal data recorded on the SD card or the like. It is decoded and amplified as an audio signal. Then, the amplified audio signal is output to the speaker 132 and the audio signal processing unit 141. The audio playback unit 131 may be a CD drive, a CD playback function, a one-segment tuner, or the like.

  The speaker 132 is mechanically attached to the inside of the housing 100 of the car navigation device 10. The speaker 132 outputs the audio signal output from the audio playback unit 131 as audio. One or two speakers 132 are mounted on the car navigation apparatus 10.

  The display input unit 133 includes a display unit 134 and an input unit 135. The display unit 134 is a liquid crystal display unit, and the input unit 135 is a touch panel attached on the liquid crystal screen of the liquid crystal display unit. The display unit 134 displays a map image, a display image indicating the current position, and the like, and the input unit 135 is operated by a user and used to input a music reproduction instruction and the like.

  The acceleration data correction unit 140 includes an audio signal processing unit 141, an acceleration signal processing unit 142, a signal synthesis unit 143, and a frequency-amplitude table 144. The audio signal processing unit 141 removes high frequency components from the audio signal reproduced (output) by the audio reproducing unit 131, and then decomposes the audio signal into frequency components by performing Fourier transform, and decomposes it into frequency components. Audio signal.

  The acceleration signal processing unit 142 removes high-frequency components from the acceleration data in the three axis directions detected by the acceleration sensor 124, and then performs a Fourier transform for each acceleration data in each axis direction, thereby converting the acceleration data into each axis direction. Decompose into frequency components.

  The signal synthesizer 143 performs temporal timing adjustment between the acceleration data decomposed into frequency components and the audio signal decomposed into frequency components, and then the audio decomposed into frequency components from the acceleration data decomposed into frequency components. By removing the influence due to the signal and performing inverse Fourier transform, acceleration data from which the influence due to the vibration of the speaker 132 is removed can be obtained.

  The timing adjustment between the acceleration data and the audio signal is delayed by the acceleration sensor 124 when the audio output from the speaker 132 becomes a physical vibration and moves through the housing 100 of the car navigation device 10 to reach the acceleration sensor 124. In this case, it is measured in advance, and the audio signal is delayed by this delay time, thereby matching the time timing with the detected acceleration data. This timing adjustment will be described later.

  Further, the signal synthesis unit 143 refers to the frequency-amplitude table 144 and removes the influence of the audio data of the acceleration data for each frequency (the influence of the vibration of the speaker). Since the acceleration sensor 124 detects acceleration in each of the three axis directions, the signal synthesis unit 143 also removes the influence of the audio signal on each of the three axis directions of the acceleration data.

  In the frequency-amplitude table 144, the sound output from the speaker 132 becomes a physical vibration and travels through the housing 100 of the car navigation device 10 to reach the acceleration sensor 124, and how much acceleration data is detected by the acceleration sensor 124. It is a table showing the relationship with the acceleration sensor output value for every frequency and sound volume whether it is influencing.

  FIG. 2 shows the magnitude of the sound output at the acceleration sensor 124 for each frequency when a certain test sound signal data is reproduced (read) by the audio reproducing unit 131 and output from the speaker 132 as sound. The frequency-amplitude table 144 which measured whether it is detected as acceleration data is shown.

  The frequency-amplitude table 144, when reproducing certain test audio signal data, Fourier-transforms the reproduced audio signal and decomposes it into frequency bands f1 to f20, taking this on the horizontal axis, and the vertical axis for test The amplitudes 1 to 14 of the audio signal of the audio signal data are taken. The frequency-amplitude table 144 indicates how much the predetermined amplitude is detected by the acceleration sensor 124 in the audio signal in each frequency band.

  For example, in the frequency band f1, the amplitude of the audio signal of the test audio data is 6, and the amplitude of the acceleration data detected by the acceleration sensor 124 at that time is 15. Therefore, 15 which is the amplitude of the acceleration data is described at a place where the frequency band f1 and the amplitude 6 of the audio signal intersect.

  Further, in the frequency band f2, the amplitude of the audio signal of the test audio signal data is 7, and at that time, the acceleration sensor 124 detected 16 amplitudes, so the frequency band f2 and the audio signal amplitude 7 intersect. Describes 16 which is the amplitude of the acceleration data. The same applies to other frequency bands, and the audio signal and the amplitude of acceleration data for each frequency band are stored in association with each other.

  Further, this frequency-amplitude table 144 is prepared for each volume. This is to take into account that the vibration of the casing 100 is not constant depending on the volume of the sound output from the speaker 132 even if the sound has the same frequency. For example, in the case of the same frequency, if the volume is lowered, the vibration transmitted through the housing 100 is considered to be reduced. However, the amount of decrease in the volume and the amount of decrease in the vibration transmitted through the housing (the width where the vibration is reduced) are directly proportional. Not always. That is, even when the volume is greatly decreased (or increased), the vibration transmitted through the housing does not always decrease (or increase) in direct proportion to the volume. Therefore, by preparing the frequency-amplitude table 144 for each volume, it is possible to calculate the vibration amount (speaker vibration that affects the acceleration data) transmitted through the housing in accordance with the volume decrease amount (adjustment amount).

  Next, with reference to FIG. 3, an operation for removing the influence of the vibration due to the sound output from the speaker 132 on the acceleration data of the acceleration sensor 124 in this embodiment will be described. FIG. 3 is a flowchart of a correction operation for removing the influence of the vibration of the speaker 132 from the acceleration data of the acceleration sensor 124.

  In step S301, the audio reproduction unit 131 reads the audio signal data recorded on various media such as an SD card, combines it, and outputs it as an audio signal. The output audio signal is output as audio from the speaker 132 in step S302. In step S303, when the sound is output from the speaker 132, the speaker 132 physically vibrates, and this vibration vibrates the casing 100 of the car navigation device 10 (step S303).

  The vibration of the housing 100 moves through the housing 100 and reaches the acceleration sensor 124. In step S304, the acceleration signal processing unit 142 acquires acceleration data. This acceleration data includes fluctuations in acceleration caused by vibration of the casing 100 caused by the sound signal being output as sound from the speaker 132, and fluctuations in acceleration caused by movement of the vehicle in which the car navigation device 10 is installed. It is. In step S305, the acceleration signal processing unit 142 performs Fourier transform on the acceleration data detected by the acceleration sensor 124 for each of the three axis directions, and decomposes the data into frequency components.

  Following the process of step S305, the process of step S306 is performed. That is, when the audio reproduction unit 131 is reproducing audio signal data in step S301, the audio signal processing unit 141 performs Fourier transform on the audio signal being reproduced and decomposes it into frequency components in step S306.

  In FIG. 3, it is described that the Fourier transform of the audio signal in step S306 is performed after the acceleration data in step S305 is Fourier transformed, but the present invention is not limited to this. After the output of the sound signal in step S301, the process of Fourier transforming the acceleration data in steps S302 to S305 and the process of Fourier transforming the sound signal in step S306 may be performed in parallel.

  There is a time lag between the sound output from the speaker 132 and the effect of the sound signal included in the acceleration data detected by the acceleration sensor 124. This is related to the time until the vibration generated by the sound output from the speaker 132 reaches the acceleration sensor 124 through the housing 100. Therefore, in step S307, the signal synthesizer 143 performs timing adjustment to match the temporal difference between the acceleration data Fourier-transformed in step S305 and the audio signal Fourier-transformed in step S306.

  In step S308, the signal synthesizer 143 refers to the frequency-amplitude table 144 to obtain the influence of the sound signal in each frequency band on the acceleration data, and the influence of the sound signal Fourier-transformed from the Fourier-transformed acceleration data. In step S309, the signal synthesizer 143 performs inverse Fourier transform on the acceleration data from which the influence due to the audio signal has been removed, and outputs the result as corrected acceleration data.

  The process of removing the Fourier-transformed audio signal from the Fourier-transformed acceleration data in step 308 will be further described with reference to FIGS. FIG. 4 is a diagram schematically showing a state in which the audio signal is removed from the acceleration data that is Fourier-transformed together.

  FIG. 4A shows, with time, how much amplitude the frequency data has in each frequency band by performing Fourier transform on the acceleration data detected by the acceleration sensor 124 in the acceleration signal processing unit 142. 4B, the audio signal processing unit 141 performs Fourier transform on the audio signal, and the signal synthesis unit 143 refers to the frequency-amplitude table 144 for the amplitude of the audio signal of each frequency band subjected to the Fourier transform. FIG. 4 shows how much the audio signals in the respective frequency bands vibrate the casing and are detected by the acceleration sensor 124, and show them with time.

  The signal synthesizer 143 subtracts the influence of the audio signal shown in FIG. 4B for each frequency band from the Fourier-transformed acceleration data shown in FIG. FIG. 4C shows the acceleration component for each frequency band from which the influence of the audio signal is removed. As is clear from a comparison between FIG. 4A and FIG. 4C, an acceleration with an amplitude smaller than the amplitude of the acceleration detected by the acceleration sensor 124 remains, and this influences the vibration caused by the sound output from the speaker 132. Acceleration data when not received. Various subtraction methods are conceivable. For example, the subtraction can be performed by adding the inverse phase of the Fourier-transformed audio signal to the Fourier-transformed acceleration data.

  FIG. 5 shows the acceleration data at a certain time among the Fourier-transformed acceleration data of FIG. 4A, and shows the actual acceleration component and the influence due to the audio signal. .

  In the above description, the acceleration sensor 124 detects triaxial acceleration data, and for each triaxial acceleration data, the audio signal decomposed into frequency components is removed from the acceleration data decomposed into frequency components. However, more accurately, the above method is applied to the acceleration sensor 124 for detecting uniaxial acceleration data. Is desired.

  Further, when the acceleration sensor 124 that detects triaxial acceleration data is used, it is preferable to provide a frequency-amplitude table 144 for each axis. That is, when the speaker 132 is installed in the front-rear direction with respect to the navigation device 10, the influence of the vibration of the speaker 132 is greatly added to the front-rear direction axis with respect to the navigation device 10 among the axes of the acceleration sensor 124. This is because the influence in the vertical direction is considered to be small.

  If the installation direction of the speaker 132 is known in advance, the audio signal (vibration of the speaker 132) may be removed only from the corresponding axis (in the above-described case, the axis in the front-rear direction).

  Next, a method for creating the frequency-amplitude table 144 shown in FIG. 2 will be described with reference to FIG. FIG. 6 is a flowchart showing an operation for creating a frequency-amplitude table in the car navigation device 10 of the present embodiment.

  In step S601, first, it is determined whether or not the vehicle on which the car navigation device 10 is mounted is stopped. This determination may be performed by determining whether the engine is operating or stopped, or may be performed by determining whether the vehicle is moving by the GPS receiving unit 122. If the vehicle is not stopped, the process is terminated. If it is determined that the vehicle is stopped, the audio reproduction unit 131 reproduces the test audio signal data in step S602. The audio signal data for testing is not limited, and any audio signal data may be used.

  In step S603, the audio signal processing unit 141 performs Fourier transform on the audio signal of the test audio signal data being reproduced and decomposes it into each frequency band, and the audio signal processing unit 141 further performs the analysis for each frequency band of the audio signal. Store the amplitude. In step S604, the user operates the input unit 135 to operate the playback volume of the audio signal and perform playback at a predetermined volume. In step S604, the playback volume is manipulated, but it is assumed that the playback volume has been manipulated in advance for the sake of simplicity. In step S605, sound based on the sound signal of a predetermined volume being reproduced is output from the speaker 132. When sound is output from the speaker 132, the vibration of the speaker 132 is transmitted through the housing 100 and reaches the acceleration sensor 124.

  In step S606, the vibration reaching the acceleration sensor 124 is detected as acceleration data, and the acceleration data is Fourier-transformed by the acceleration signal processing unit 142 and decomposed into each frequency band. Since the acceleration data detected at this time by the acceleration sensor 124 is that when the vehicle is stopped, it is considered that all of the acceleration data is influenced by the vibration of the speaker 132. In step S607, timing adjustment is performed to correct a time lag between the audio signal and the output of the acceleration sensor 124.

  Regarding the direction of gravity, it is conceivable that the acceleration data includes gravitational acceleration even when the vehicle is stopped. Therefore, it is preferable to remove the gravitational acceleration from the acceleration data for the axis in the gravity direction.

  In step S608, the amplitude of each frequency band of the stored audio signal and the amplitude of each frequency band of the acceleration data detected by the acceleration sensor 124 are associated with each other and stored in a storage unit (not shown). This may be a frequency-amplitude table 144 as shown in FIG. The audio signal and the acceleration data are stored in association with each other for each predetermined volume value.

  Alternatively, the amplitude of each frequency band of the audio signal when the amplitude of each frequency band of the acceleration data detected by the acceleration sensor 124 is 1 may be calculated and stored in association with each other.

  The example in which the acceleration data correction apparatus of the present invention is incorporated in the car navigation apparatus has been described above, but the acceleration data correction apparatus of the present invention is not limited to this embodiment. For example, acceleration data and audio signals may be acquired by connecting to acceleration data and audio signal input / output terminals of an existing car navigation device 10 to correct errors in measurement data of an acceleration sensor in the car navigation device. Good.

DESCRIPTION OF SYMBOLS 10 Car navigation apparatus 100 Case 110 Control part 120 Navigation part 121 Current position detection part 122 GPS receiving part 123 Autonomous navigation part 124 Acceleration sensor 125 Map matching part 126 Map database 130 Audio visual part 131 Audio reproduction part 132 Speaker 133 Display input part 134 Display Unit 135 Input Unit 140 Acceleration Data Correction Unit 141 Audio Signal Processing Unit 142 Acceleration Signal Processing Unit 143 Signal Synthesis Unit 144 Frequency-Amplitude Table

Claims (5)

An acceleration data correction device for removing the influence of vibration of the built-in speaker on the output of the acceleration sensor in an electronic device in which a housing is provided with a built-in speaker and an acceleration sensor,
Audio signal processing means for decomposing an audio signal supplied to the built-in speaker into frequency components;
Acceleration signal processing means for decomposing the output of the acceleration sensor into frequency components;
An acceleration data correction apparatus comprising: a signal synthesis unit that removes the audio signal decomposed into the frequency components from the output of the acceleration sensor decomposed into the frequency components.   The acceleration data correction device includes a frequency-amplitude table indicating the magnitude of the influence of vibration of the speaker based on the audio signal on the output of the acceleration sensor, and the signal synthesis unit is decomposed into the frequency components. 2. The acceleration data correction apparatus according to claim 1, wherein the frequency-amplitude table is referred to when the audio signal decomposed into the frequency components is removed from the output of the acceleration sensor.   The frequency-amplitude table is created based on the output of the acceleration sensor decomposed into the frequency component and the audio signal decomposed into the frequency component when the acceleration data correction device is stopped. The acceleration data correction device according to claim 2, wherein   The signal synthesis means delays the audio signal decomposed into the frequency components by a time until vibration of the speaker affects the output of the acceleration sensor, from the output of the acceleration sensor decomposed into the frequency components. The acceleration data correction apparatus according to claim 1, wherein the acceleration data correction apparatus is removed. The electronic device is a navigation device,
The navigation device includes the acceleration data correction device according to any one of claims 1 to 4.

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