JPH102748A - Self-contained navigator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-contained navigator which is inexpensive, while requiring no special work. SOLUTION: There are arranged two speed-detection means A and B, which emit an ultrasonic wave to the road surface to detect a ground speed from a Doppler-shift frequency of the reflected wave and the means are set at a fixed angle in the direction of yawing a vehicle. An arithmetic means 11a is provided to perform vector composition of outputs from the individual velocity detection means A and B and calculates the velocity in the ongoing direction from the magnitudes of vectors for calculating the ongoing direction of the vehicle. Thus, an inexpensive sensor can be used as on ultrasonic sensor to simultaneously calculate the velocity and the ongoing direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous navigation system for detecting the speed and direction of travel and identifying the position of a vehicle by comparing the detected position with a map in car navigation and the like.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a conventional autonomous navigation device. 1 is a gyro sensor for detecting a change in direction, 2 is an A / D converter for A / D converting the output of the gyro sensor 1, and 3 is a microprocessor capable of calculating speed and direction and communicating with the outside. 3a is an ECU
(Speed control means) for detecting the vehicle speed based on the wheel speed pulse signal output from the (engine control unit), and 3b is a direction detection means for detecting the traveling direction of the vehicle from the output of the gyro sensor which is A / D converted. Reference numeral 3c denotes communication means for outputting the speed and traveling direction obtained by the speed detecting means 3a and the direction detecting means 3b to the outside. The vehicle position is specified by comparing this speed and direction with the map.

[0003] Here, the method of connection with the ECU differs depending on the vehicle type / year, so that it can be handled only by a specialized trader, special construction is required, and accompanying costs are incurred. In addition, the gyro sensor 1 is usually the most expensive component in the autonomous navigation device, and is a major factor preventing a reduction in the price of the device.

On the other hand, a Doppler radar method is known as a method of detecting a vehicle speed by means other than a wheel speed pulse signal. FIG. 7 is a conceptual diagram of a conventional speed detecting means, in which an electromagnetic wave or an ultrasonic wave is emitted to a road surface, and a vehicle speed is detected by using the fact that the Doppler frequency of a reflected wave is a function of speed. . Generally, when using electromagnetic waves,
Since the frequency band is difficult to handle in the gigahertz band and the parts to be used are expensive, the present invention considers only the Doppler radar system using ultrasonic waves. If this Doppler radar system is used, the speed can be calculated with high accuracy, and no special construction is required, and it is only necessary to mount a transmission / reception sensor with a magnet or the like at a position where ultrasonic waves can be emitted to the road surface.

[0005]

However, the conventional autonomous navigation system using the wheel speed pulse has a problem that a special construction and a large cost associated therewith are required. Also, a gyro sensor for detecting a change in direction is expensive, and there is a problem that the cost is increased.

An object of the present invention is to provide an autonomous navigation device which is inexpensive and does not require special works.

[0007]

According to a first aspect of the present invention, there are provided two speed detecting means for emitting an ultrasonic wave to a road surface and detecting a ground speed from a Doppler shift frequency of a reflected wave, and these speed detecting means are provided. Is installed at a certain angle in the yaw direction of the car, the output of each speed detecting means is vector-composited, the speed in the traveling direction is calculated from the magnitude of the combined vector, and the traveling direction of the vehicle is calculated from the direction of the combined vector. It is provided with a calculating means for calculating.

According to a second aspect of the present invention, in the two velocity detecting means, the center frequency of the ultrasonic wave to be emitted is set to a value separated by more than the expected maximum Doppler shift frequency.

According to a third aspect of the present invention, a partition plate is provided between the two speed detecting means.

According to a fourth aspect of the present invention, there is provided a memory which can be backed up, a map matching means for comparing a vehicle position with a map, and the calculating means, wherein the calculating means calculates a distance error calculated by the map matching means. And based on the direction error, determine the mounting angle error of the speed detection means and write the result to the memory,
When calculating the speed and the traveling direction, the correction is performed based on the mounting angle error written in the memory.

[0011]

According to the first aspect of the present invention, since the two speed detecting means are installed at a certain angle in the yaw direction of the vehicle, the speed change is determined by the output of each speed detecting means. Since the change in the magnitude and the change in the traveling direction appear in the change in the output ratio of the two speed detecting means, the speed and the traveling direction of the vehicle can be determined simultaneously by determining the magnitude and direction of these combined vectors.

According to the second aspect of the invention, it is possible to prevent interference between the two speed detecting means. According to the invention of claim 3, it is possible to prevent interference between the two speed detecting means.

According to the fourth aspect of the present invention, it is possible to correct the speed error and the traveling direction error caused by the mounting error of the speed detecting means.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram of an autonomous navigation device according to Embodiment 1 of the present invention, and FIG. 2 is a conceptual diagram thereof. FIG.
In the figures, A and B are speed detecting means, and the inside has the same configuration. 4 is a transmission sensor for emitting an ultrasonic wave, 5 is a reception sensor for receiving a reflected wave, 6 is an oscillating means for generating a fundamental wave of the emitted ultrasonic wave, and 7 is an amplifier for amplifying an output of the reception sensor 5. Means 8 for mixing the amplified received signal and the emitted fundamental wave to generate a beat, and 9 for removing high frequency components from the output of the mixing means and extracting a difference component, that is, a Doppler shift frequency component. Low-pass filter 10, frequency detecting means for counting Doppler shift frequency, 11
Is a microprocessor, a calculating means 11 for calculating the speed and traveling direction of the vehicle from the outputs of the speed detecting means A and B.
a and communication means 11b for outputting the calculated speed and traveling direction to the outside.

FIG. 2 shows how the speed and traveling direction of the vehicle can be calculated from the outputs of two speed detecting means attached to the front of the vehicle.

By simply combining two speed detecting means using an inexpensive ultrasonic sensor, it is possible to simultaneously obtain the speed and the traveling direction without special wiring work and expensive gyro sensors. Here, the speed detecting means A and B are mounted at a right angle.
If it is not 速度, calculation of speed and traveling direction is possible. As for the configuration of the speed detecting means, other methods such as linear detection using a diode are also possible.

This autonomous navigation device can also be configured as follows. That is, the oscillation frequency of the oscillating means 6 is made different between the speed detecting means A and B. For example, assuming that the assumed maximum Doppler shift frequency is 3 kHz, the center frequency is set such that the ultrasonic wave of 40 kHz is emitted from the speed detecting means A and the ultrasonic wave of 45 kHz is emitted from the speed detecting means B. Set to a value separated by more than the maximum Doppler shift frequency. Thus, interference between the two speed detecting means can be prevented, and the speed can be detected accurately.

(Embodiment 2) FIG. 3 is a conceptual diagram of an autonomous navigation apparatus according to Embodiment 2 of the present invention, in which a partition plate 12 is provided between speed detecting means A and B. As in the case where the oscillating frequency of the oscillating means 6 is different between the speed detecting means A and B in the first embodiment, the interference between the two speed detecting means can be prevented, and the speed can be accurately detected. be able to.

(Embodiment 3) FIG. 4 is a block diagram of an autonomous navigation apparatus according to Embodiment 3 of the present invention, and FIG. 5 is a conceptual diagram of the same. In FIG. 4, reference numeral 13 denotes a backup-capable memory such as an EEPROM, 14 denotes a map matching means for comparing the position of the vehicle with a map, and 15 denotes a map stored in a CD-ROM or the like.

FIG. 5 shows the speed detecting means A and B in FIG.
Shows the state where the center line is attached with a deviation of Δφ from the front of the vehicle. In this case, even if the vehicle is traveling straight, there is a difference between the outputs of the speed detecting means A and B, and the arithmetic means 11a deviates from the straight traveling by Δφ Is determined to be moving in the wrong direction. Then, the map matching means 14 compares the position of the vehicle with the map 15, and feeds back the resulting deviation of the traveling direction to the microprocessor 11. The microprocessor 11 then calculates back the yaw direction mounting angle error and stores it in the memory 13. Next, when the traveling direction is obtained from the outputs of the speed detecting means A and B, the contents of the memory 13 are read and the traveling direction is corrected accordingly, thereby canceling the yaw direction mounting angle error, and the traveling direction is accurately detected. Can be calculated.

Also, as shown in FIG. 2, the mounting angle error in the pitch direction affects the speed. Then, similarly, the map matching means 14 compares the data with the map 15 to obtain a speed error and feeds back the speed error to the microprocessor 11. The microprocessor 11 then calculates back the mounting angle error in the pitch direction and stores it in the memory 13. Next, when the speed is obtained from the outputs of the speed detecting means A and B, the contents of the memory 13 are read out and the speed is corrected accordingly, thereby canceling the mounting angle error in the pitch direction and accurately calculating the speed. Can be.

[0022]

According to the present invention, an inexpensive autonomous navigation device which does not require a special construction and an expensive gyro sensor associated with the conventional extraction of the wheel speed pulse signal can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of an autonomous navigation device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of the autonomous navigation device according to the first embodiment of the present invention.

FIG. 3 is a conceptual diagram of an autonomous navigation device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of an autonomous navigation device according to a third embodiment of the present invention.

FIG. 5 is a conceptual diagram of an autonomous navigation device according to a third embodiment of the present invention.

FIG. 6 is a block diagram of a conventional autonomous navigation device.

FIG. 7 is a conceptual diagram of a conventional speed detecting means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gyro sensor 2 A / D converter 3 Microprocessor 3a Speed detection means 3b Direction detection means 3c Communication means 4 Transmission sensor 5 Reception sensor 6 Oscillation means 7 Amplification means 8 Mixing means 9 Low pass filter (LPF) 10 Frequency detection means 11 Microprocessor 11a arithmetic means 11b communication means 12 partition 13 memory 14 map matching means 15 map

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G09B 29/10 G01S 7/52 B

Claims (4)

[Claims] 1. Two speed detecting means for emitting an ultrasonic wave to a road surface and detecting a ground speed from a Doppler shift frequency of a reflected wave are provided, and these speed detecting means are provided at a certain angle in the yaw direction of the vehicle. And an arithmetic means for calculating the speed in the traveling direction from the magnitude of the combined vector, and calculating the traveling direction of the vehicle from the direction of the combined vector. Autonomous navigation device. 2. The autonomous navigation according to claim 1, wherein the center frequency of the ultrasonic waves to be emitted is set to a value separated by a value equal to or more than an expected maximum Doppler shift frequency. Place. 3. An autonomous navigation device according to claim 1, wherein a partition plate is provided between said two speed detecting means. 4. A memory which can be backed up, a map matching means for comparing the position of the vehicle with a map, and the calculating means, wherein the calculating means can also calculate a distance error and a direction error calculated by the map matching means. Determining the mounting angle error of the speed detecting means, writing the result in the memory, and performing the correction based on the mounting angle error written in the memory when calculating the speed and traveling direction. The autonomous navigation device according to claim 1, wherein