JPH07280827A - Speed detector and navigation system - Google Patents

Abstract

PURPOSE:To detect the speed of a mobile with no influence of the gravity or the receiving conditions of GPS by detecting the speed of mobile based on the low frequency components in an oscillation spectrum. CONSTITUTION:An acceleration sensor 2 secured to the trunk of an automobile detects oscillation generated through running of the automobile. An output signal S1 from the sensor is amplified through an amplifier 4 to produce an analog signal S2 which is passed through a filter 5 in order to extract a signal S3 in the frequency band of 0.5-5Hz. The extracted signal S3 is fed to a detecting circuit 6 and a smoothing circuit 7 for accumulation and an output signal S4 therefrom is fed to a signal level detector 8 comprising a level comparator or an A/D converter in order to detect the speed of the automobile. Since only the low frequency band of oscillation detected through the sensor 2 is extracted through the filter 5 and processed, the speed of an automobile can be detected with no influence of the gravitational acceleration on a slope.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1, 8 and 9) Action (FIGS. 1, 8 and 9) Example (FIGS. 1 to 1) 9) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed detecting device and a navigation device, and can be applied to, for example, a car navigation device.

[0003]

2. Description of the Related Art Conventionally, GPS (Global Positioning Sys
tem) A GPS receiver is a device that measures the position of a moving body such as an automobile using radio waves from a satellite. This GP
A system in which an S receiver is mounted on a moving body and the current position and traveling direction of the moving body are displayed in real time on a display is called a navigation device.

The navigation device uses the GPS receiver to obtain the absolute velocity and absolute position (latitude and longitude) of the moving body.
The current position and the moving direction of the moving body are obtained based on the moving direction and the moving direction, and the current position and the moving direction are overlapped and displayed on the map read from the recording medium such as a CD-ROM.

Further, the speed can be obtained from the GPS receiver. As another speed detecting method, a method of detecting using electric signals from wheels of an automobile or a rotating part of a transmission, or acceleration of a moving body such as an automobile in a traveling direction (front-back direction) is detected by an acceleration sensor. There are a detection method of detecting the speed by integrating the acceleration and a detection method of detecting the speed using the Doppler effect of a sound wave or a radio wave.

[0006]

However, in the method of detecting the speed of the moving body from the rotating parts such as the wheels and the transmission, the output method of the signal line used for the detection and the arrangement of the cable wiring of the signal line are provided. Since the position and the like differ depending on the vehicle type, there is a problem that it takes time to take out the signal line and process the signal.

Further, the method of detecting the velocity of the moving body by integrating the acceleration in the traveling direction has a problem that a large cumulative error occurs with the passage of time because the integral calculation is performed. Further, on a slope or the like, there is a problem that a larger cumulative error occurs because of an error in gravitational acceleration corresponding to the slope angle sin θ of the slope.

Further, in the detection method in which the speed of the moving body is obtained by utilizing the Doppler effect of sound waves or radio waves, the mounting position of the detection device must be outside the moving body, so that there is a problem that mounting maintenance is difficult. is there.

In the navigation device, which is one of the detection methods for obtaining the speed of a moving body by using radio waves, the GP
Although the speed can be obtained by receiving the S radio wave, there is a problem that the speed cannot be obtained because the GPS radio wave cannot be received in the shadow of a high-rise building such as a building or a place such as a tunnel. Even if GPS radio waves are received, if the moving body has a low speed such as 10 to 20 [km / h] or the GPS satellite is in poor condition,
There is a problem that it is not possible to obtain a highly accurate and reliable speed.

The present invention has been made in consideration of the above points, and can be easily attached to a moving body, and the speed of the moving body is not affected by the influence of gravitational acceleration due to a slope or the reception state of GPS radio waves. The present invention is intended to propose a speed detection device and a navigation device capable of detecting the.

[0011]

In order to solve such a problem, in the present invention, an acceleration sensor (2) which is detachably attached to a moving body and detects vibration of the moving body, and an acceleration sensor (2). A velocity detecting means (3, 10, 14) for detecting the velocity of the moving body on the basis of the low frequency component of the vibration spectrum component of the moving body thus detected is provided.

Further, in the navigation device having the GPS receiving means, the first speed detecting means for detecting the speed of the moving body based on the received signal obtained from the GPS receiving means, and the vibration spectrum component of the moving body are detected, Second speed detecting means (3, 10, 14) for detecting the speed of the moving body based on the low frequency component of the vibration spectrum component is provided.

Further, in the navigation device having the GPS receiving means, the first speed detecting means for detecting the speed of the moving body based on the received signal obtained from the GPS receiving means, and the vibration spectrum component of the moving body are detected, Second speed detecting means (3, 10, 14) for detecting the speed of the moving body based on the low frequency component of the vibration spectrum component
And the speed detected by the first speed detecting means and / or the second speed
The control means for controlling the reproducing means, the display means, or other equipment based on the speed detected by the detecting means is provided.

[0014]

The vibration of the moving body is detected by the acceleration sensor (2) which is detachably attached to the moving body, and is detected by the acceleration sensor (2) in the speed detecting means (3, 10, 14). The velocity of the moving body is detected based on the low frequency component of the vibration spectrum component of the moving body. Further, in the navigation device having the GPS receiving means, the speed of the moving body is detected by the first speed detecting means based on the received signal obtained from the GPS receiving means, the vibration spectrum component of the moving body is detected, and the second Speed detecting means (3, 10, 1
According to 4), the velocity of the moving body is detected based on the low frequency component of the vibration spectrum component. For these reasons, it can be easily attached to the moving body, and the speed of the moving body can be detected without being affected by the gravitational acceleration due to the slope and the receiving state of GPS radio waves.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

The overall structure of the speed detecting device is shown in FIG. The speed detecting device 1 is composed of an acceleration sensor 2 for detecting the acceleration of the automobile and a computing device 3 for detecting the speed by the vibration detected by the vibration sensor 2. The arithmetic unit 3 includes an amplifier 4 for amplifying a signal from the acceleration sensor 2, a filter 5 for extracting a specific low frequency band, a detection circuit 6 for detecting a signal input from the filter 5, and a signal after the detection. It comprises a smoothing circuit 7 for cumulative addition and a signal level detector 8.

The acceleration sensor 2 may be fixed to the vehicle in order to extract the acceleration applied to the vehicle. The acceleration sensor 2 detects the vibration generated by the running of the vehicle by detecting the acceleration of the vehicle, and outputs the sensor output signal S1 which is the detection result to the amplifier 4. Further, since the vibration detected by the acceleration sensor 2 is small, the amplifier 4 outputs the sensor output signal S1 sent from the acceleration sensor 2.
After inputting, the sensor output signal S1 is amplified with an amplification degree according to the output sensitivity of the acceleration sensor 2.

Here, the acceleration sensor 2 is fixed to the trunk of the automobile, and the vibration detected by the acceleration sensor 2 during traveling is analyzed by FFT (fast Fourier transform).
~ Shown in FIG. Figure 2 shows the idling of a gasoline vehicle (that is, the engine is stopped and the speed is 0 [km / h
h]), 5 [km / h] running, and 10 [km / h] running, the spectrum of vibration in the longitudinal direction is shown. In addition, Fig. 3 and Fig. 4 show that when the gasoline car is idling,
The vertical and horizontal vibration spectra at 5 [km / h] running and 10 [km / h] running are shown. Similarly, FIG. 5, FIG. 6 and FIG. 7 show spectrums of vibrations in the front-rear direction, the up-down direction and the left-right direction at idling of a diesel-powered vehicle at 5 [km / h] and 10 [km / h] respectively. Show.

As can be seen from FIGS. 2 to 7, the difference between the idling state and the running state (that is, 5 [km / h], 10 [km / h]) in any of the front-rear, up-down and left-right directions. Occurs, and the difference is 10 to 20 [d in the band of 5 [Hz] or less.
B]. Further, it can be seen from FIGS. 3 and 6 that the vibration during idling increases in the band of 10 [Hz] or higher. However, this is due to the vibration of the engine rotation,
The vibration at this time is higher in diesel vehicles than in gasoline vehicles. Further, the vibration caused by the engine is 8 Hz or more in view of the engine speed, although the magnitude varies depending on the vehicle type. Therefore, the difference between the idling state and the running state is less than 5 [Hz]. This difference appears with respect to the movement of the automobile, and vibrations in any direction occur, so that the speed can be detected. For this reason, the filter 5 is a bandpass filter that extracts only the low frequency band of 0.5 to 5 [Hz].

In the above structure, the acceleration sensor 2 is fixed to the trunk of the automobile and detects the acceleration of the automobile to detect the vibration generated by the traveling of the automobile.
Since the sensor output signal S1 which is the detection result has small vibration, it is input to the amplifier 4 and amplified. The analog signal S2 amplified by the amplifier 4 is input to the filter 5.
Since the filter characteristic of the filter 5 is set so as to extract the band of 0.5 to 5 [Hz], only the band of 0.5 to 5 [Hz] of the analog signal S2 output from the amplifier 4 is extracted. The analog signal S3 extracted by the filter 5 is input to an electric circuit including a detection circuit 6 and a smoothing circuit 7 for cumulative addition. After this, the analog signal S
4 is input to a signal level detector 8 including a level comparator or an A / D converter to detect the speed of the automobile.

According to the above construction, the vibration of the automobile is detected by the acceleration sensor 2, only the low frequency band of the detected vibration is extracted by the filter 5, and the calculation processing is performed. The vehicle speed can be detected without being affected by the above. Further, since the acceleration sensor 2 is detachable, it is possible to detect the speed of the automobile with easy attachment.

In the above embodiment, the filter 5
As described above, a bandpass filter for extracting only a low frequency band of 0.5 to 5 [Hz] is described, but the present invention is not limited to this, and a lowpass filter for extracting a band of 5 to 8 [Hz] is used. Is also good. Since the influence of the engine appears in the band above 5 [Hz], a steep low-pass filter is used.

In the above embodiment, the acceleration sensor 2 for detecting the acceleration of the automobile, the amplifier 4 for amplifying the signal from the acceleration sensor 2, and the specific low frequency band among the bands amplified by the amplifier 4 are extracted. Although the filter 5, the detection circuit 6, the smoothing circuit 7 for cumulative addition, and the signal level detector 8 have been described, the present invention is not limited to this, and an amplifier is provided between the filter 5 and the detection circuit 6. The same effect can be obtained even if one is added.

Another speed detecting device is shown in FIG. 8 which is designated by the same reference numeral as in FIG. The speed detecting device 9 includes an acceleration sensor 2 and a computing device 10. Arithmetic unit 10
The output signal S4 from the smoothing circuit 7 in the A / D converter 11
It is digitized by inputting into. After that, the digital signal S5 is input to the digital signal processing unit 12, and the speed of the vehicle may be detected by comparing the input digital value with the digital value of the digital signal processing unit 12.

Further, another speed detecting device is shown in FIG. 9 in which the same reference numerals as in FIG. 8 are attached. This speed detection circuit 13
Is composed of the acceleration sensor 2 and the arithmetic unit 14.
The sensor output signal S1 output from the acceleration sensor 2 is passed through the amplifier 4, the filter 5, and the A / D converter 11 in this order to
The signal S6 digitized by the / D converter 11 is input to the digital signal processing unit 15. This digital signal processing unit 1
In 5, first, the AC component of the input digital signal S6 is converted into an absolute value and cumulatively added. The speed of the vehicle may be detected by collating the calculation result obtained at this time with the digital value of the digital signal processing unit 15.
As a method of converting the AC component into an absolute value at this time, a method of calculating the difference between the reference voltage of the analog amplifier and the output signal, or a calculation of a high-pass filter having a low frequency (for example, 0.1 [Hz] or less) in the output signal is performed. Therefore, there is a method of producing an AC component.

In the above embodiment, the vibration sensor 2 of the speed detecting device 1 is fixed to the trunk of the automobile. However, the present invention is not limited to this, and the vibration sensor 2 may be fixed to any portion inside and outside the automobile. However, the same effect can be obtained. At this time, the vibration sensor may be lightly fixed to the automobile with an adhesive tape or the like.

Further, in the above-mentioned embodiment, the speed detecting device 1 is attached to the automobile to detect the speed, but the present invention is not limited to this, and the moving body such as a vehicle, an airplane, a ship and the like. Even if the speed detecting device 1 is attached to the above, the same effect can be obtained.

Further, in the above-mentioned embodiment, the case where only the speed detecting device 1 is fixed to the moving body has been described.
The present invention is not limited to this, and the speed detection device 1, 9 or 13 may be used in combination with another speed detection device. For example, by using the speed detecting device 1, 9 or 13 together with GPS, the speed can be detected even in a place where GPS radio waves cannot be received such as a shadow of a high-rise building such as a building or a tunnel. Further, it is possible to detect a low speed of about 10 to 20 [km / h] per hour, which has been difficult to detect accurately in the past.

Further, in the navigation device using both the speed detection device 9 or 13 and GPS, when it is judged from the detected speed that the vehicle is idling, the TV monitor is turned on by utilizing the fact that the vehicle is stopped. Or
Character information such as FM multiplex can be displayed on the display. Further, since the power generated by the alternator decreases when the vehicle is stopped, it is possible to adjust the power consumption of the electric system and adjust the volume and the like according to the traveling speed. The adjustment of the volume and the like not only lowers the level of the volume and the like when stopped, but also suppresses the level down of the low range and the high range. For example, in a case where a sound such as an information sound is produced by a voice, such as voice guidance of a navigation device, the level at the time of stopping and at the time of running is changed.

In addition to this, for example, it is possible to change the display of the illumination of the speaker or the like between when the vehicle is stopped and when the vehicle is running, to protect complicated key operations during traveling, and to stabilize other sensors while the vehicle is stopped. Since the DC component is output, calibration such as offset voltage is performed. Further, it can be used for various purposes such as automatically stopping the fan heater or the like when external vibration such as an earthquake is detected.

[0031]

As described above, according to the present invention, the vibration of the moving body is detected, and the speed of the moving body is detected from the detected output level. It is possible to detect the speed of the moving body without the need. Further, when used together with a speed detecting device such as GSP, the speed detecting device can be connected without processing the moving body, and the speed can be detected with high accuracy. Further, it is possible to automatically detect stop and movement of the moving body, detect permission / prohibition of operation of entertainment equipment, etc., and easily confirm safety.

[Brief description of drawings]

FIG. 1 is a block diagram showing a speed detecting device according to an embodiment of the present invention.

FIG. 2 is a graph showing a spectrum of a sensor output signal obtained from a front-back vibration of a gasoline vehicle.

FIG. 3 is a graph showing a spectrum of a sensor output signal obtained from vertical vibration of a gasoline vehicle.

FIG. 4 is a graph showing a spectrum of a sensor output signal obtained from horizontal vibration of a gasoline vehicle.

FIG. 5 is a graph showing a spectrum of a sensor output signal obtained from vibration in a front-rear direction of a diesel vehicle.

FIG. 6 is a graph showing a spectrum of a sensor output signal obtained from a vertical vibration of a diesel vehicle.

FIG. 7 is a graph showing a spectrum of a sensor output signal obtained from a lateral vibration of a diesel vehicle.

FIG. 8 is a block diagram showing another speed detecting device.

FIG. 9 is a block diagram showing another speed detecting device.

[Explanation of symbols]

1, 9, 13 ... Speed detection device, 2 ... Acceleration sensor,
3, 10, 14 ... Arithmetic unit, 4 ... Amplifier, 5 ... Filter, 6 ... Detection circuit, 7 ... Smoothing circuit, 8 ... Signal level detector, 11 ... A / D converter, 12 , 15 ……
Digital signal processor.

Claims (12)

[Claims] 1. An acceleration sensor which is detachably attached to a moving body and detects a vibration of the moving body, and based on a low frequency component of a vibration spectrum component of the moving body detected by the acceleration sensor. And a speed detecting means for detecting the speed of the moving body. 2. The speed detecting device according to claim 1, wherein the speed detecting means extracts only a component in a predetermined band from the low frequency components to detect the velocity of the moving body. 3. The speed detecting means extracts only the component in a band of 5 [Hz] or less from the low frequency components to detect the velocity of the moving body. The speed detection device described in. 4. A GPS receiving means for receiving GPS radio waves to detect position information of a moving body, a recording medium for storing map information, and map information obtained by the GPS receiving means according to the position of the moving body. In a navigation device having a reproducing means for reproducing the information from the recording medium and a display means for displaying the map information, a first device for detecting the speed of the moving body based on a reception signal obtained from the GPS receiving means. And a second speed detecting unit for detecting a vibration spectrum component of the moving body and detecting the speed of the moving body based on a low frequency component of the vibration spectrum component. Navigation device to do. 5. The navigation device according to claim 4, wherein the second speed detecting means extracts only a component in a predetermined band from the low frequency components to detect the velocity of the moving body. . 6. The second speed detecting means extracts only the component in the band of 5 [Hz] or less from the low frequency components and detects the velocity of the moving body. The navigation device according to claim 5. 7. When the reception condition of the GPS radio wave is good, the first speed detecting means detects the speed of the moving body based on the reception of the GPS radio wave, and the reception condition of the GPS radio wave is not good. The second speed detecting means detects the speed of the moving body based on a low frequency component of the vibration spectrum component of the moving body. Navigation device. 8. When the GPS radio wave reception condition is not good, the first speed detecting means detects the speed of the moving body based on the reception of the GPS radio wave, and the first speed detecting means The navigation device according to claim 4, 5, 6 or 7, wherein the speed not detected is compensated by the speed detected by the second speed detecting means. 9. GPS receiving means for receiving GPS radio waves to detect position information of a moving body, a recording medium for storing map information, and map information obtained by the GPS receiving means according to the position of the moving body. In a navigation device having a reproducing means for reproducing the information from the recording medium and a display means for displaying the map information, a first device for detecting the speed of the moving body based on a reception signal obtained from the GPS receiving means. Speed detecting means; second speed detecting means for detecting a vibration spectrum component of the moving body, and detecting the speed of the moving body based on a low frequency component of the vibration spectrum component; and the first speed detecting means. Control means for controlling the reproduction means, the display means or other equipment based on the speed detected by the means and / or the speed detected by the second detection means. Nabigeshiyon and wherein the. 10. The navigation device according to claim 9, wherein the second speed detecting means extracts only a component in a predetermined band from the low frequency components and detects the velocity of the moving body. . 11. The navigation device according to claim 9, wherein the control means controls an operable function of the device. 12. The control means controls switching of whether or not information is displayed on the display means so that the information is not displayed on the display means when the moving body is traveling. The navigation device according to claim 9 or 11.