JP2856310B2 - Speed detection device and navigation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order. BACKGROUND OF THE INVENTION Problems to be Solved by the Invention Means for Solving the Problem (FIG. 1) Function (FIG. 1) Embodiment (FIGS. 1 to 9) Effects 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) There is a GPS receiver as a device for measuring the position of a moving body such as an automobile using radio waves from a satellite. This GP
A so-called navigation device is a system in which the S receiver is mounted on a moving object and displays the current position and traveling direction of the moving object on a display in real time.

[0004] The navigation device uses an absolute speed and an absolute position (latitude and longitude) of a moving object obtained from a GPS receiver.
The current position and the traveling direction of the moving object are obtained based on the traveling direction and the traveling direction, and the obtained position and the traveling direction are superimposed on a map read from a recording medium such as a CD-ROM.

[0005] Further, speed can be obtained from a GPS receiver. Further, as another speed detecting method, a method of detecting using an electric signal from a wheel of a car or the like or a rotating portion of a transmission or the like, or an acceleration in a traveling direction (front-back direction) of a moving body such as a car by an acceleration sensor is used. There are a detection method of detecting the speed by integrating the acceleration and detecting the speed, and a detection method of obtaining the speed using the Doppler effect of a sound wave or a radio wave.

[0006]

However, in a method of detecting the speed of a moving body from a rotating portion such as a wheel or a transmission, a method of outputting a signal line used for the detection and a method of arranging a cable line of the signal line are used. Since the position and the like differ depending on the vehicle type, there is a problem that it takes time to take out signal lines and perform signal processing.

In the method of detecting the speed of the moving body by integrating the acceleration in the traveling direction, there is a problem that a large accumulated error occurs with the lapse of time because the integration operation is performed. Also, on a slope or the like, there is a problem that a larger cumulative error occurs because an error of the gravitational acceleration corresponding to the slope angle sin θ of the slope occurs.

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

In a navigation device, which is one of the detection methods for obtaining the speed of a moving object using radio waves,
The speed can be obtained by receiving the S radio wave, but there is a problem that the speed cannot be obtained because the GPS radio wave cannot be received, for example, in a shadow of a high-rise building such as a building or in a place such as in a tunnel. Even when a GPS radio wave is received, a high-accuracy and reliable speed is obtained when the speed of the moving object is low, for example, 10 to 20 [km / h], or when the state of the GPS satellite is poor. There is a problem that you can not.

The present invention has been made in consideration of the above points, and is easy to attach to a moving object, and is capable of speeding the moving object without being affected by the gravitational acceleration due to the slope or the receiving condition of the GPS radio wave. A speed detecting device and a navigation device capable of detecting a vehicle speed are proposed.

[0011]

According to the present invention, there is provided an acceleration sensor (2) detachably attached to a metal part of a moving body, for detecting vibration of the moving body, and an acceleration sensor (2). ) Is provided with speed detecting means (3) for detecting the speed of the moving object based on the high-frequency component of the vibration spectrum component of the moving object detected by the method.

In the navigation device, a GPS
First speed detecting means for detecting the speed of the moving object based on a reception signal obtained from the receiving means; detecting a vibration spectrum component of the moving object; and detecting the speed of the moving object based on a high-frequency component of the vibration spectrum component. Second speed detecting means (3) for detecting is provided.

[0013]

The vibration of the moving body is detected by an acceleration sensor (2) detachably attached to the metal part of the moving body, and the speed detecting means (3) detects the vibration of the moving body by the acceleration sensor (2). The speed of the moving object is detected based on the high frequency component of the vibration spectrum component. Further, in the navigation device, first speed detecting means for detecting the speed of the moving object based on a reception signal obtained from the GPS receiving means;
A vibration spectrum component of the moving body is detected, and the speed of the moving body is detected by the second speed detecting means (3) based on a high-frequency component of the vibration spectrum component. Therefore, the speed of the moving body can be easily detected without being affected by the gravitational acceleration due to the slope and the receiving state of the GPS radio wave.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 shows the overall configuration of the speed detecting device. The speed detecting device 1 includes a vibration sensor 2 for detecting vibration generated by running of an automobile, and an arithmetic device 3 for detecting a speed based on the vibration detected by the vibration sensor 2.

The vibration sensor 2 detects front and rear vibrations among vibrations generated when the automobile is running, and outputs a sensor output signal S1 as a detection result to the arithmetic unit 3.
The arithmetic unit 3 detects the speed from the sensor output signal S1 detected by the vibration sensor 2. The arithmetic unit 3 includes an amplifier 4 for amplifying a signal from the vibration sensor 2, a filter 5 for extracting a specific high-frequency band, a detection circuit 6, a smoothing circuit 7 for cumulative addition, and an A / D converter for digitizing an analog signal. It consists of eight.

Since the vibration detected by the vibration sensor 2 is small, the amplifier 4 receives and amplifies the sensor output signal S1 sent from the vibration sensor 2. Here, the FFT at idling (that is, a state in which the engine is stopped and the speed is 0 [km / h])
(Fast fourier transform) Analyzed sensor output signal S
2 is shown in FIG. Similarly, at 20
[Km / h], speed 40 [km / h], speed 60 [km / h]
h], the spectrum of the sensor output signal S1 is shown in FIGS. Further, FIG. 6 shows a simplified and graphed spectrum of each sensor output signal shown in FIGS.

From these figures, it can be seen that the spectrum of the sensor output signal S1 increases in proportion to the speed in the band of 800 to 1600 [Hz]. Therefore, the filter 5 is a bandpass filter of 24 [dB / oct], and the filter characteristic is set so as to extract a high frequency band of 800 to 1600 [Hz] in which the spectrum of the sensor output signal S1 increases in proportion to the speed. .

FIG. 7 shows A / D conversion of the sensor output signal at the time of FIG. M. S (Root Mean Square)
A value, that is, a value obtained by calculating an effective value is shown. From this figure, when the speed is 0 [km / h], the output voltage is 0.005 [V] and 10 [km].
/ H] 0.015 [V], 20 [km / h] 0.012
5 [V], 30 [km / h] 0.032 [V], 40
At [km / h], the relationship of 0.035 [V] can be read. Therefore, the speed can be detected by creating such a conversion table in the present apparatus or in a set requiring the speed.

In the above configuration, the vibration sensor 2 is installed on the metal part of the trunk of the vehicle, and detects the vibration in the front-rear direction among the vibrations generated when the vehicle runs.
Since the sensor output signal S1 as a result of this detection has a small amplitude, it is input to the amplifier 4 in the arithmetic unit 3 and amplified. The analog signal S2 amplified by the amplifier 4 is input to the filter 5. The filter characteristic of this filter 5 is 800
1600 [Hz], 8 out of the analog signal S2 output from the amplifier 4 is set.
Only the band from 00 to 1600 [Hz] 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 accumulative addition, and then output to an A / D converter 8.

Here, as the output after the digital signal S3 is detected and smoothed by the detection circuit 6 and the smoothing circuit 7, a voltage output corresponding to the speed of the vehicle is obtained. The voltage output obtained at this time is 6 for every 10 [km / h] as shown in FIG.
[DB] There is a relationship that changes. For this reason, 0-60 km
/ H] can be A / D converted to 12 bits. This 0-60
FIG. 9 shows an example in which [km / h] is assigned to 12 bits.

The analog signal S4 output from the smoothing circuit 7 is input to the A / D converter 8 and digitized. Further, in a signal processing unit (not shown),
The speed according to the signal level is obtained using a conversion table.

According to the above configuration, by installing the vibration sensor 2 on the metal part of the trunk of the automobile, the speed of the automobile can be detected with easy installation. Further, the vibration of the vehicle is detected by the vibration sensor 2, and only the high frequency band of the detected vibration is extracted by the arithmetic unit 3 and subjected to the arithmetic processing, so that the speed of the vehicle is not affected by the gravitational acceleration on the slope. Can be detected.

In the above-described embodiment, the vibration sensor 2 in the speed detection device 1 detects the vibration in the front-rear direction among the vibrations of the vehicle. However, the present invention is not limited to this. A similar effect can be obtained by detecting the vertical or horizontal vibration among the vibrations of the automobile.

In the above embodiment, the vibration sensor 2 of the speed detecting device 1 is installed on the metal part of the trunk of the automobile. However, the present invention is not limited to this. It may be mounted at any position as long as it is a hard metal part such as a body frame or a mounting rail of a chair to which the traveling vibration of an automobile is transmitted.

In the above embodiment, the A / D converter 8 for converting an analog signal into a digital signal is disposed after the amplifier 4, the filter 5, the detection circuit 6, and the smoothing circuit 7, but the present invention is not limited thereto. However, the A / D converter may be arranged between the amplifier 4 and the filter 5 or between the filter 5 and the detection circuit 6. In addition, the A / D converter 8
In the case of using a device that performs high-speed operation such as (digital signal processing), or in the case of performing operation processing with a high-speed microcomputer, the same effect can be obtained even if the smoothing circuit 7 is omitted.

Further, in the above-described embodiment, the description has been given of the case where the speed is detected based on the vibration of the automobile. However, the present invention is not limited to this, and the same applies to a mobile body such as a vehicle, an airplane or a ship. The effect of can be obtained.

Further, in the above-described embodiment, the case where the vibration is detected by installing one vibration sensor on the moving body has been described. However, the present invention is not limited to this, and a plurality of vibration sensors may be mounted on the moving body. And vibration may be detected.

Further, in the above-described embodiment, the case where only the speed detecting device 1 is installed on the moving body has been described.
The present invention is not limited to this, and the speed detection device 1 and another speed detection device may be used together and installed on a moving body. In this case, another speed detecting device can be connected without processing the moving body.

For example, the speed detector 1 according to the present invention and G
By using the PS together, the speed can be detected even in a place where GPS radio waves cannot be received, such as in a shadow of a high-rise building such as a building or in a tunnel. In addition, it is possible to detect a low speed of about 10 to 20 [km / h], which is difficult to accurately detect with the GPS. For this reason, by using the speed detecting device 1 according to the present invention and another speed detecting device together, it is possible to obtain speed information with higher precision than the speed information obtained by each speed detecting device.

[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. The speed of the moving object can be detected. Further, when used in combination with a speed detecting device such as a GSP, the speed detecting device can be easily connected without processing the moving body, and a highly accurate speed can be detected.

[Brief description of the 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 longitudinal vibration of an automobile during idling.

FIG. 3 is a graph showing a spectrum of a sensor output signal obtained from a longitudinal vibration of an automobile at a speed of 20 [km / h].

FIG. 4 is a graph showing a spectrum of a sensor output signal obtained from a longitudinal vibration of an automobile at a speed of 40 [km / h].

FIG. 5 is a graph showing a spectrum of a sensor output signal obtained from a longitudinal vibration of an automobile at a speed of 60 [km / h].

FIG. 6 is a graph showing a relationship between a spectrum of a vibration sensor output due to a front-back vibration of the automobile and a vehicle speed.

FIG. 7 is a graph showing the R.R. M. 4 is a graph showing a relationship between an S value and a vehicle speed.

FIG. 8 is a table showing a voltage output according to the speed of an automobile after detection and smoothing according to an embodiment of the present invention.

FIG. 9 is a table showing the state of the 12-bit A / D conversion in FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Speed detection device, 2 ... Vibration sensor, 3 ... Calculation device, 4 ... Amplifier, 5 ... Filter, 6 ... Detection circuit,
7: smoothing circuit, 8: A / D converter.

──────────────────────────────────────────────────続 き Continuation of front page (58) Fields investigated (Int.Cl. ⁶ , DB name) G01P 3/00 G01C 21/00 G01S 5/14

Claims (9)

(57) [Claims] An acceleration sensor removably attached to a metal portion of a moving body for detecting vibration of the moving body, and a high-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 object based on the speed. 2. The speed detecting device according to claim 1, wherein said speed detecting means extracts only a component in a predetermined band from said high frequency components and detects the speed of said moving body. 3. The speed detecting device according to claim 1, wherein said speed detecting means extracts only a component of a band around 1 [kHz] from said high frequency component and detects the speed of said moving body. The speed detecting device according to the above. 4. A GPS receiving means for receiving GPS radio waves to detect positional information of a moving body, a recording medium for storing map information, and map information obtained by the GPS receiving means and corresponding to the position of the moving body. A playback device for playing back from the recording medium and a display means for displaying the map information, wherein a first speed of the moving body is detected based on a reception signal obtained from the GPS reception means. Speed detecting means, and second speed detecting means for detecting a vibration spectrum component of the moving body and detecting a speed of the moving body based on a high-frequency component of the vibration spectrum component. Navigation device. 5. The navigation device according to claim 4, wherein said second speed detecting means extracts only a component in a predetermined band from said high frequency components and detects the speed of said moving body. 6. The speed detecting device according to claim 4, wherein said second speed detecting means extracts only a component in a band around 1 [kHz] from said high frequency component and detects the speed of said moving body. Item 6. The navigation device according to item 5. 7. When the reception condition of the GPS radio wave is good, the first speed detecting means detects the speed of the moving object based on a reception signal obtained from the GPS reception signal, and The second speed detecting means detects the speed of the moving object based on a high-frequency component of the vibration spectrum component of the moving object when the speed is not good. 7. The navigation device according to 6. 8. When the reception condition of the GPS radio wave is not good, the first speed detection means detects the speed of the moving body based on a reception signal obtained from the GPS reception means, and The navigation device according to claim 4, wherein a speed not detected by the speed detecting means is supplemented by a speed detected by the second speed detecting means. 9. A vibration spectrum of a moving object detected by an acceleration sensor.
A filter for extracting a high-frequency component of the vector component, a level detector for detecting the output level of the filter, and a level detected by the level detector and a value stored in advance.
Comprising a processing unit for detecting the speed of the vehicle by matching bets
A speed detecting device characterized by the above-mentioned.