JP2000292532A - Angular velocity detection method and its system - Google Patents

Abstract

(57) [Problem] To provide a novel angular velocity detection system exceeding the performance of a tuning fork type angular velocity sensor that cannot completely match sense resonance because of two axes. SOLUTION: A marker 2 incorporating a resonator which resonates in a medium-long wave radio wave of 100 to 500 kHz is mounted on a road lane 1.
The vehicle 3 is provided with an antenna 4 capable of transmitting the radio wave and a plurality of antennas 5, 6, 7 capable of receiving the radio wave at three places on the left, right and center of the front bumper. When the traveling vehicle 3 changes the traveling direction, the reception level of the radio wave is inversely proportional to the distance from the marker 2 to the reception antenna.
The horizontal distance of the marker is calculated from the reception levels of the three receiving antennas when it is considered that the marker has passed over the marker 2,
Further, a turning angle of the vehicle is obtained based on the distance between the markers and the lateral distance, and an angular velocity is obtained based on the traveling time of the vehicle between the markers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detecting method for detecting an angular velocity (yaw rate) of a traveling vehicle by detecting a left or right turn of the traveling vehicle, and a system therefor.

[0002]

2. Description of the Related Art Conventionally, an angular velocity sensor has been used to detect the angular velocity of a traveling vehicle. FIG. 5 shows a configuration of a conventional piezoelectric vibration gyro-type angular velocity sensor. FIG.
, The angular velocity sensor is a U-shaped metal diaphragm 1
01, two opposing metal diaphragms 102, 103
Is arranged in a direction perpendicular to the U-shaped metal diaphragm 101, that is, in a so-called tuning fork shape. When the fixed shaft 104 is fixed to the base, a pair of tuning forks rotates with respect to the bending of the traveling vehicle. It is configured to rotate around the detection axis 106. On both outer side surfaces of the U-shaped metal diaphragm 101, driving piezoelectric elements 101a,
1b are joined, and one side surface of the upper metal vibration plates 102, 103 is connected to the sensing piezoelectric elements 102a, 1b.
03a is joined. Drive elements 101a, 1
01b indicates that the sense elements 102a and 103a are 1
The pair of tuning forks is driven so as to vibrate in the direction indicated by 05 and move closer to or away from each other. In that case, in order to increase the sensitivity, the tuning fork is driven at the resonance frequency.

FIG. 6 shows a circuit configuration of the conventional angular velocity sensor. First, the drive system takes out the output of one drive element 101b and inputs the signal, a charge amplifier 111, an AGC circuit 112 that produces a DC signal that determines the gain of the drive circuit 113 from the output of the charge amplifier 111, and the other. Drive element 101
and a drive circuit 113 for driving a.
The sensor system includes two sense elements 102a,
A charge amplifier 114 for converting the composite signal from the signal 103a into a voltage, a 90 ° shift circuit 115 for shifting the signal by 90 degrees, a synchronous detection circuit 116 for synchronous detection with the output of the charge amplifier 111 of the driving system, a synchronous detection signal And a low-pass filter (LPF) 117 for demodulating a signal to be output from the angular velocity sensor.

Next, the operation of the conventional angular velocity sensor will be described. First, the resonance frequency of the tuning fork (generally 1
The driving elements 101a and 101b are driven at a frequency of about 2 kHz. However, since the output of the charge amplifier 111 includes noise, a band-pass filter circuit having a resonance frequency as a center is generally added after the charge amplifier 111. The output of the charge amplifier 111 is band-pass filtered and the AGC circuit 1
12, is converted into a DC signal corresponding to the output of the charge amplifier 111, and is input to the drive circuit 113. The output of the drive circuit 113 is determined so that the DC signal has a constant value, and the tuning fork composed of the metal diaphragms 102 and 103 is driven at a constant speed (resonance frequency × amplitude).

When a rotating force is applied to the driven tuning fork about the rotation detecting shaft 106 shown in FIG. 5, a Coriolis force Fc is generated in the metal diaphragms 102 and 103 in the opposite direction. Works in the direction of bending the sense elements 102a, 103a, and the sense elements 102a, 103
If the output of a is a signal driven by driving, the carrier wave is AM-modulated so that the signal due to Coriolis force becomes a modulated wave. The signal due to the vibration of the sense elements 102a and 103a is shifted by 90 degrees with respect to the signal due to the drive of the drive elements 101a and 101b.
The signal is shifted by 90 degrees by the 0 ° shift circuit 115, so that the signal is in phase with the driving signal. Next, the outputs of the drive system and sensor system charge amplifiers 111 and 114 are
When synchronous detection is performed by the synchronous detection circuit 116, a signal generated by Coriolis force is demodulated, and the demodulated signal includes a drive signal (1).
２2 kHz), the low-pass filter 117 is used to obtain the required signal of 100 Hz or less.
After being low-pass filtered at, it is output as an angular velocity detection output.
As described above, the above-described conventional angular velocity sensor detects the angular velocity, thereby turning the traveling vehicle in the left-right direction (yaw).
Can be detected.

[0006]

However, in the above-described conventional angular velocity sensor, the tuning frequency of the tuning fork vibrator made of a pair of metal diaphragms must be strictly matched with the resonance frequency including the temperature characteristics. This has resulted in an increase in cost for frequency adjustment and a decrease in productivity. FIG.
As shown in the above, the tuning fork (vibration) resonance and the sense resonance cannot be matched due to the limitation of two axes regardless of the non-resonance type or the resonance type, and the sensitivity is small and the temperature drift is increased. As a result, the angular velocity cannot be detected with high accuracy. An object of the present invention is to solve such a conventional problem and to provide a novel angular velocity detecting method and a system capable of detecting an angular velocity with high accuracy.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention embeds a marker in which a resonator that resonates with an electromagnetic wave is installed at an equal interval on a road, and enables a vehicle to transmit and receive the electromagnetic wave. When a traveling vehicle changes its direction of travel by incorporating multiple antennas and circuits, the reception level of electromagnetic waves is inversely proportional to the distance from the marker to the receiving antenna. The horizontal distance of the marker is calculated from the reception level, the turning angle θ of the vehicle is obtained based on the distance between the markers and the horizontal distance, and the angular velocity is further calculated based on the traveling time of the vehicle between the markers. It is what we asked for. As a result, it is possible to detect the angular velocity with high accuracy and to cope with future development toward the infrastructure (road).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a plurality of antennas installed in a vehicle emit electromagnetic waves toward a traveling road, are buried in the road at regular intervals, and resonate with the electromagnetic waves. The reflected electromagnetic waves from the marker with the built-in resonator were received by a plurality of antennas installed in the vehicle, and the horizontal distance from the marker was calculated from the reception levels of the electromagnetic waves received by the plurality of antennas. Determine the turning angle of the vehicle based on the lateral distance and the distance between the markers,
Further, the angular velocity detecting method is characterized in that the angular velocity is calculated from the traveling time of the vehicle between the markers, and has an effect that the angular velocity of the traveling vehicle can be detected with high accuracy.

According to a second aspect of the present invention, there is provided a marker which is embedded in a road at regular intervals and has a built-in resonator for resonating with electromagnetic waves, a plurality of antennas mounted on a vehicle and capable of transmitting and receiving electromagnetic waves, An angular velocity detection device, calculating a lateral distance from the marker from reception levels of electromagnetic waves received by the plurality of antennas, and calculating a turning angle of the vehicle based on the calculated lateral distance and a distance between the markers. ,
Further, the angular velocity detection system is characterized in that the angular velocity is calculated from the travel time of the vehicle between the markers, and has an effect that the angular velocity of the traveling vehicle can be detected with high accuracy.

According to a third aspect of the present invention, there is provided an angular velocity detecting device, comprising: means for transmitting and receiving an electromagnetic wave; means for detecting an electric field level of a received electromagnetic wave; 3. The angular velocity detection system according to claim 2, further comprising means for performing A / D conversion, and means for inputting the A / D-converted voltage value and performing a predetermined operation, wherein the angular velocity of the traveling vehicle is determined by a simple circuit configuration. Has the effect of being able to detect with high accuracy.

According to a fourth aspect of the present invention, the transmitting antenna is a loop antenna, the receiving antenna is a ferrite bar antenna, and each is incorporated in a front bumper of the vehicle. 3. The angular velocity detection system according to item 3, wherein the angular velocity of the traveling vehicle can be detected with high accuracy using a compact antenna structure.

According to a fifth aspect of the present invention, there is provided the angular velocity detecting system according to any one of the second to fourth aspects, wherein the resonator of the marker is a ferrite resonator which does not require a battery. This has the effect that the angular velocity of the traveling vehicle can be detected with high accuracy using an easy marker.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment) FIG. 1 shows an infrastructure structure according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a road lane, which is divided into several lanes according to the width of the road. Reference numeral 2 denotes a marker that does not require a battery buried at equal intervals, for example, every 2 m, in the center of the road lane 1.
A resonator that resonates with an electromagnetic wave in the middle and long wave band of 00 kHz is incorporated. Reference numeral 3 denotes a vehicle, and the front bumper has a transmitting antenna 4 as a loop antenna, and a first receiving antenna 5, a second receiving antenna 6, and a third receiving antenna 7, which are ferrite bar antennas at both ends and at three places at the center. Is provided. The installation location of these antennas is not limited to the front bumper.

FIG. 2A shows a circuit configuration of the angular velocity detecting device according to the present embodiment. 11 is a transmission amplifier,
Reference numeral 12 denotes one transmitting antenna, and 13 denotes three receiving antennas. Reference numeral 14 denotes a receiving amplifier, and 15 denotes a mixer, three of which are installed so as to be able to correspond to three receiving antennas 13, respectively. 16 is a three-input A / D converter, 17 is a microcomputer, 18 is timing logic, the transmission timing of the transmission amplifier 11 and the mixer 15
Control of the reception timing.

Next, the operation of this embodiment will be described. Under the control of the microcomputer 17, medium-long waves (100 to 500 kHz) at 4 ms intervals and a duty ratio of 50%
The electromagnetic wave z) is emitted from the transmission amplifier 11 and the transmission antenna 12. FIG. 2B shows the envelope of the electromagnetic wave. When the medium-long electromagnetic wave emitted from the transmitting antenna 12 as a loop antenna reaches the marker 2 on the road, the resonator (ferrite LC resonator) incorporated in the marker 2 resonates, and the electromagnetic wave is reflected from the marker 2 I do. The reflected electromagnetic wave is transmitted to the receiving antenna 13 which is a ferrite bar antenna.
To reach. The electromagnetic wave received by each receiving antenna is amplified by the receiving amplifier 14, and as shown in FIG.
In step 5, the transmission level is cut, and only the reception level is extracted. The voltage of the reception level is converted to an A / D converter 16.
A / D conversion is performed, and is taken into the microcomputer 17.

As shown in FIG. 3, since the electromagnetic wave is reflected from the marker only when each antenna approaches the marker, it is considered that the time when the envelope reaches the maximum is the time when passing the marker, and Is the time when one marker passes through the next marker, and is the distance. Further, since the reception level of the electromagnetic wave is inversely proportional to the distance from the marker to the receiving antenna, the horizontal distance of the marker from the reception level of the first, second, and third receiving antennas when it is considered that the marker has passed over the marker. d (m) can be calculated. Next, as shown in FIG. 4, if the vehicle passes right above the marker 2a and then passes to the left of the next marker 2b in the left direction d (m), the distance between the markers is L (m). Then, the turning angle θ of the vehicle becomes θ = tan −1 (d / L). Further, assuming that the traveling time of the vehicle between the markers is T, the angular velocity δθ / δt becomes δθ / δt = θ / T, and since d and L have the accuracy in the unit of cm, the angular velocity having sufficient accuracy is obtained. Can be detected. Also,
In normal traveling, d is considered to be sufficiently smaller than L, so that it can be approximated by the following equation. θ = 360 ° × (d / 2πL)

As described above, according to the present embodiment, markers with built-in LC resonators that resonate and reflect 100 to 500 kHz medium and long wave electromagnetic waves are buried at equal intervals in the center of the road lane. By incorporating a plurality of antennas capable of transmitting and receiving medium-long-wave electromagnetic waves, the lateral distance between the vehicle and the marker can be detected, and the angular velocity can be accurately detected from the lateral distance.

The reason why the lane marker system in the present embodiment employs the electromagnetic wave medium-long-wave resonant reflection method is as follows. (1) The reach of electromagnetic waves is longer than other methods, and the in-vehicle equipment, particularly the mounting position of the antenna, has a high degree of freedom. (2) The marker may be of a type that does not require a battery, and is easy to handle as an infrastructure side such as roadside maintenance. (3) Since it is a medium-long wave, it is resistant to bad environments, and can be used even if the marker is submerged or buried in snow, and there is no performance degradation. (4) The lowest cost system can be constructed.

[0019]

As apparent from the above embodiment, the present invention embeds a marker in which a resonator that resonates with an electromagnetic wave is embedded at a fixed interval on a road, and has a plurality of vehicles capable of transmitting and receiving an electromagnetic wave on a vehicle. An antenna and a transmission / reception circuit are provided, a lateral distance from a marker is detected from reception levels of electromagnetic waves received by a plurality of antennas, and a turning angle of the vehicle is obtained based on the detected lateral distance and a distance between the markers. Further, since the angular velocity is calculated from the traveling time of the vehicle between the markers, the angular velocity of the traveling vehicle can be detected with high accuracy. Therefore, if the angular velocity detection system according to the present invention is applied to a suspension control device, attitude control can be performed with high accuracy, and if the system is applied to a navigation device, route search and destination search can be performed with high accuracy. Further, by using the lane marker system of the present invention, I
Various systems in TS (Intelligent Transport System) can be constructed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration on an infrastructure side according to an embodiment of the present invention;

FIG. 2A is a block diagram illustrating a circuit configuration according to an embodiment of the present invention. FIG. 2B is a timing waveform diagram of transmission / reception electromagnetic waves according to the embodiment of the present invention.

FIG. 3 is a timing waveform chart of a received electromagnetic wave in the present embodiment.

FIG. 4 is an explanatory diagram for calculating an angular velocity according to the embodiment;

FIG. 5 is a schematic perspective view showing a configuration of a conventional angular velocity sensor.

FIG. 6 is a block diagram showing a circuit of a conventional angular velocity sensor.

FIG. 7 is a characteristic diagram showing frequency characteristics of a conventional angular velocity sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Road lane 2 Marker 3 Vehicle 4 Transmitting antenna 5, 6, 7 Receiving antenna 11 Transmitting amplifier 12 Transmitting antenna 13 Receiving antenna 14 Receiving amplifier 15 Mixer 16 A / D converter 17 Microcomputer 18 Timing logic

Claims (5)

[Claims] An electromagnetic wave is emitted from a plurality of antennas installed on a vehicle toward a traveling road, and reflected electromagnetic waves from a marker embedded in the road at regular intervals and having a built-in resonator that resonates with the electromagnetic wave are reflected on the vehicle. Receiving with a plurality of installed antennas, calculating the lateral distance from the marker from the reception level of the electromagnetic waves received by the plurality of antennas, the vehicle based on the calculated lateral distance and the distance between the markers, An angular velocity detection method comprising: determining a turning angle; and calculating an angular velocity from a travel time of the vehicle between markers. 2. A marker which is embedded in a road at regular intervals and incorporates a resonator that resonates with electromagnetic waves, a plurality of antennas mounted on a vehicle capable of transmitting and receiving electromagnetic waves, and an angular velocity detecting device, A lateral distance from the marker is calculated from a reception level of the electromagnetic wave received by the antenna, a turning angle of the vehicle is obtained based on the calculated lateral distance and a distance between the markers, and the vehicle travels between the markers. An angular velocity detection system for calculating an angular velocity from time. 3. An angular velocity detecting device comprising: means for transmitting and receiving an electromagnetic wave; means for detecting an electric field level of a received electromagnetic wave; means for A / D converting a voltage of the detected received electric field level; 3. The angular velocity detection system according to claim 2, further comprising: means for inputting the D-converted voltage value and performing a predetermined calculation. 4. The transmitting antenna is a loop antenna,
The angular velocity detecting system according to claim 2, wherein the receiving antenna is a ferrite bar antenna, and each of the receiving antennas is incorporated in a front bumper of the vehicle. 5. The angular velocity detection system according to claim 2, wherein the marker resonator is a ferrite resonator that does not require a battery.