JPH08327376A - Navigation device - Google Patents

Abstract

PURPOSE: To conduct always an accurate navigation by a constitution in which a proper coefficient can be selected depending on the state of a traveling body and which can be used to convert speed information. CONSTITUTION: The data from a pulse generator 32 to a counter 22 are supplied to a position measurement operation part 23 for self-contained navigation to obtain speed data after being multiplied by a specific vehicle speed coefficient value. The vehicle speed coefficient is available in two types, namely a vehicle speed coefficient 1 obtained by averaging for a short time and a vehicle speed coefficient 2 obtained by averaging for a long time, is set to a proper initial value in advance, and is successively corrected after starting driving. Each coefficient value is stored at a RAM 15 and storage data are updated for each correction. Also, a current position is calculated based on the speed data calculated by an operation part 23 and the driving direction data by a gyro device 24. In this case, when the current position coordinate can be calculated by a position measurement operation part 13 for GPS, the data are supplied to the operation part 23 to calculate the current position. When the current position coordinate cannot be calculated by an operation part 13, the data of the current position coordinates calculated by the operation part 23 are supplied to a CPU 14 and, for example, a road map and a current position are displayed in a display 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device which is mounted on a moving body and detects its speed and the like.

[0002]

2. Description of the Related Art Conventionally, various navigation devices to be mounted on automobiles have been developed. This navigation device is, for example, a CD-RO in which road map data is stored.
It is composed of a large-capacity data storage means such as M, a current position detection means, and a display device for displaying a road map near the detected current position based on the data read from the data storage means. In this case, as a means for detecting the current position, one using a positioning system called a GPS (Global Positioning System) using an artificial satellite for positioning (hereinafter simply referred to as GPS), a traveling direction of the vehicle, a traveling direction For example, there is an autonomous navigation method that tracks changes in the current position from the departure point based on information such as speed.

If a positioning system based on a positioning signal such as GPS is used, relatively accurate positioning is possible,
Although it is possible to know the current position accurately, in the case of such a positioning system, positioning cannot be performed in a state in which a positioning signal from a satellite or the like cannot be received, such as when traveling in a tunnel.

For this reason, navigation devices that have been developed in recent years include positioning using positioning signals such as GPS and positioning using autonomous navigation that tracks changes in position based on information such as the traveling direction and traveling speed of the vehicle. In some cases, positioning is performed on both sides, and during a period in which positioning by a positioning signal is not possible, positioning is performed by autonomous navigation so that positioning can always be performed.

[0005]

By the way, in the case of performing positioning by autonomous navigation, at least information on the traveling direction (traveling direction) and traveling speed of the vehicle is required, and the information on the traveling direction is the gyro device or the geomagnetic field. The information on the traveling speed can be obtained by using a sensor or the like, and in the case of an automobile, the information on the traveling speed can be obtained by counting the number of pulses output at every predetermined rotation of the tire (axle) of the vehicle at predetermined intervals. it can.

However, when the speed is detected from the pulse output in synchronism with the rotation of the tire of the vehicle, there is a problem that an error is likely to occur in the detected speed. That is, the detected speed often deviates from the actual speed due to changes in various conditions such as changes in tire air pressure and changes in traveling environment.

On the other hand, the GPS positioning system has a function of detecting not only the current position but also the speed of the vehicle equipped with the receiver based on the reception state of the positioning signal from the satellite. .

Therefore, in the case of a navigation device equipped with both a GPS positioning system and an autonomous navigation positioning system, when GPS positioning is possible, speed information detected from the rotational speed of the axle and GPS detection are performed. There is a method in which the speed value detected from the rotational speed of the axle is corrected when there is a difference by comparing the speed information.

However, it is GPS that can correct the speed value.
It is difficult to correct the error in the detected speed value during the period when the GPS positioning signal cannot be received, and the GPS positioning signal cannot be received for a long time. In this case, the accumulated error has a large error in the detected speed, which may cause a large error in the position to be measured.

For example, when a coefficient value for converting the number of pulses output for each predetermined rotation of the axle into speed information (hereinafter referred to as a vehicle speed coefficient value) can be continuously corrected based on the data received by GPS. Has a change indicated as S1 in FIG. Here, A shown on the horizontal axis in FIG.
If the GPS positioning signal cannot be received in the period from B to B, the coefficient value cannot be corrected in this period, so that the vehicle speed coefficient value at the point A is maintained up to the point B. The change in the vehicle speed coefficient value used for positioning in navigation becomes S1 ', and the range X surrounded by the change S1 when continuously corrected and the change S1' where there is an uncorrected section (Fig. 9 indicates a hatched area), and a positioning error corresponding to the area of the area X is accumulated.

In view of the above point, the present invention has an object to make it possible to always accurately detect the speed of a moving body such as a vehicle in this type of navigation device.

[0012]

According to the present invention, when a speed proportional signal obtained from a moving body is multiplied by a predetermined coefficient to be converted into speed information, at least two coefficients are prepared for conversion, and a positioning signal is prepared. Based on the speed information obtained by receiving
The at least two coefficients are updated in different modes, and at least two coefficients are selected and used for conversion depending on the situation.

[0013]

According to the present invention, it is possible to detect speed information with a small error by selecting a coefficient that seems to be good according to the situation of the moving body and using it for conversion of speed information.

[0014]

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

FIG. 1 is a diagram showing the overall configuration of this example, which is a navigation device 10 mounted on an automobile (not shown) in this example.
Is equipped with a GPS antenna 11, a positioning signal received by the antenna 11 from a GPS satellite is received by a GPS signal reception unit 12, and the received data is supplied to a GPS positioning calculation unit 13. This GPS positioning calculation unit 13
Then, the supplied received data is analyzed to calculate the current coordinate position and its altitude, and also the moving speed and the traveling direction of the vehicle equipped with the navigation device 10. However, in the case of the positioning system using GPS, it is difficult to accurately calculate the moving speed and the traveling direction when the moving speed of the vehicle is slow (for example, when the speed is 20 km / h or less). The data of the current coordinate position here is, for example, the data of latitude and longitude which are absolute position information.

Then, a central control unit (CPU) 14 for controlling the positioning operation of this navigation device, based on each information such as the current coordinate position calculated by the GPS positioning calculation unit 13.
Supply to. The central controller 14 has a RAM 15
And the CD-ROM driver 16 are connected. In this CD-ROM driver 16, a CD-ROM (optical disk) storing road map data is set,
Based on the control of the central controller 14, this CD-ROM
Playback processing for reading the stored data of is performed.

When the GPS positioning calculation section 13 calculates the current position coordinates, the central control unit 14 controls the road map data in the vicinity of the current position to be read from the CD-ROM, and the read road is read. The map data is stored in the RAM 15. Then, the central control unit 14
Of the road map data stored in the AM 15, the road map data in the range to be displayed is read out and the video signal generation circuit 1 is read.
7, the video signal generation circuit 17 generates a video signal for displaying the road map as a video, and the video signal is output from the output terminal 18. The video signal for displaying this road map is a video signal for displaying some kind of information such as the current position and the running locus, and various information such as the current speed and the traveling direction by characters and figures.

Then, the video signal output from the output terminal 18 is supplied to the display device 31, the image receiving process is performed on the display device 31 based on the video signal, and a road map or the like is displayed on the display panel of the display device 31. Display it.

In addition to displaying such a road map in the vicinity of the present position, a road map at a position designated by the operation keys 19 or the like can be controlled by the central controller 14. It can be displayed based on.

The navigation device 10 of this example is
It is also possible to measure the current position by autonomous navigation. That is, from the pulse generator 32 provided on the side of the vehicle on which the navigation device 10 is mounted to the input terminal 2
The pulse counter 22 supplies a pulse signal as a speed proportional signal to the pulse counter 22 to detect the traveling speed of the vehicle.

In this case, the pulse signal output from the pulse generator 32 is a pulse signal proportional to the rotation speed of the axle of the automobile. For example, when the vehicle is traveling at a certain speed, a pulse signal having a cycle shown in A of FIG. 2 is output, and as the traveling speed becomes faster than that, the pulse signal of FIG.
B, the period of the pulse signal becomes faster as shown in C of FIG. Then, on the counter 22 side, for example, as shown in FIG. 2, the count value proportional to the speed can be detected by counting the number of pulses in a predetermined period t ₁ (for example, 1 second). Then, the count data of the counter 22 is supplied to the autonomous navigation positioning calculation unit 23, and the count data is multiplied by a predetermined vehicle speed coefficient value to obtain speed data.

In the case of this example, the vehicle speed coefficient values are 1 for the short-time average and 2 for the long-time average.
The following two types are prepared, and the initial values that are considered to be appropriate are set in advance for the respective vehicle speed coefficient values, and after the start of travel, the correction processing described later sequentially corrects the coefficient values to obtain accurate speed values. The data is available. In addition, each vehicle speed coefficient value is R connected to the central control unit 14.
The data is stored in a predetermined area in the AM 15, and the stored data is updated each time it is modified.

The navigation device 10 also includes a gyro device 24, detects the traveling direction of an automobile in which the navigation device 10 is mounted, and supplies the detected data to the autonomous navigation positioning calculator 23.

In the autonomous navigation positioning calculation unit 23,
Based on the speed data calculated based on the supplied count data and the traveling direction data, the traveling state of the vehicle is calculated and the current position is calculated. In this case, GPS
When the current position coordinates can be calculated by the vehicle positioning calculation unit 13, the data of the current position coordinates are supplied to the autonomous navigation positioning calculation unit 23, and the coordinate position is used as the starting point, and the traveling locus based on the traveling state from there. Then, the current position is calculated. Then, when the current position coordinates cannot be calculated by the GPS positioning calculation unit 13, the data of the current position coordinates calculated by the autonomous navigation positioning calculation unit 23 is supplied to the central control device 14, and the central control device 14 side. Based on the data of the current position coordinates, the above-described road map, current position, and the like are controlled to be displayed on the display device 31.

When the traveling speed is calculated by the calculation processing based on the positioning signal in the GPS positioning calculation unit 13, the speed data is supplied to the autonomous navigation positioning calculation unit 23.

In the autonomous navigation positioning calculation unit 23,
Speed data supplied from the GPS positioning calculation unit 13,
The difference from the speed data calculated based on the supplied count data is sequentially determined.If the difference is within a predetermined range, the vehicle speed coefficient value used for the calculation is calculated based on the speed difference. I am trying to fix it.

Next, the process of correcting the vehicle speed coefficient value by the navigation device of this example will be described with reference to the flowchart of FIG. In the following description, in order to simplify the description, the speed data calculated by the GPS positioning calculation unit 13 in the GPS positioning system is used as GPS speed data, and the count value of the counter 22 and the vehicle speed coefficient value are calculated. The velocity data obtained by multiplying by is used as sensor velocity data.

First, it is determined whether or not the GPS speed data supplied to the autonomous navigation positioning calculation unit 23 is within the usable range (step 101). In this judgment, the speed data detected by the GPS positioning system has a large detection error at a low speed, so that the speed data within the usable range can be used only when the speed is a certain speed (for example, 20 km / h or more). Step 1
Move to 02. If it is determined that the speed data is out of the usable range, or if the positioning signal cannot be received, G
If PS speed data is not supplied, the process proceeds to step 107 where GPS speed data is not used.

When it is determined that the GPS speed data is within the usable range and the process proceeds to step 102, the difference between the GPS speed data and the sensor speed data is within ± 3 m / sec. Judge whether or not. Here, if the difference between the two speeds is ± 3 m / sec or more, it is highly likely that the GPS speed data has been erroneously detected because the difference is large. Move to 107.

Then, in step 102, the difference between the two speeds is ±
When it is determined that the speed is within 3 m / sec, the speed ratio between the GPS speed data and the sensor speed data is calculated (step 103). This speed ratio is calculated based on the following equation.

[0031]

## EQU00001 ## Speed ratio = (GPS speed data) / (sensor speed data)

Then, the step 10 which is a step of correcting the vehicle speed coefficient 1 which is the vehicle speed coefficient based on the short-time averaging.
Go to 4. In this step, the vehicle speed coefficient 1 is updated based on the following equation.

[0033]

[Formula 2] Vehicle speed coefficient 1 = (old vehicle speed coefficient 1 x speed ratio x COEF
1) + [old vehicle speed coefficient 1 × (1-COEF1)] where COEF1 is a value for obtaining a short-time average, and 0 and 1
The value is between 0.01 and 0.01 here.

Next, the routine proceeds to step 105, which is a step for correcting the vehicle speed coefficient 2 which is the vehicle speed coefficient based on the long-term average. In this step, the vehicle speed coefficient 2 is updated based on the following equation.

[0035]

[Equation 3] Vehicle speed coefficient 2 = (old vehicle speed coefficient 2 x speed ratio x COEF
2) + [Old vehicle speed coefficient 2 x (1-COEF2)] where COEF2 is a value for obtaining the long-term average, 0 and 1
And a value between 0.001 in this case.

After the correction of the vehicle speed coefficient 1 and the vehicle speed coefficient 2, the corrected vehicle speed coefficient 1 is used to obtain the sensor speed based on the following equation (step 106).

[0037]

## EQU00004 ## Sensor speed = speed proportional signal × vehicle speed coefficient 1 In this example, the speed proportional signal is count data of the counter 22.

Then, using the obtained sensor speed data and the like, the positioning calculation section 23 for autonomous navigation performs positioning calculation of the current position, and after a predetermined time, the processing from step 101 is repeatedly executed.

Next, when it is determined in step 101 that the speed data is out of the usable range, or when the positioning signal cannot be received and the GPS speed data is not supplied, the difference between the two speeds is ± 3 m / in step 102. A case will be described in which it is determined that the speed is every second or more and the process proceeds to step 107. In this case, the vehicle speed coefficient 1 is corrected by the vehicle speed coefficient 2. The arithmetic expression in this case is shown by the following expression.

[0040]

[Equation 5] Vehicle speed coefficient 1 = [old vehicle speed coefficient 1 × (1-COEF
3)] + (vehicle speed coefficient 2 × COEF3) Here, COEF3 is a value for bringing the vehicle speed coefficient 1 closer to the vehicle speed coefficient 2, and is a value between 0 and 1 and is 0.01 here.

When the vehicle speed coefficient 1 is updated in step 107, the process proceeds to step 106, and the updated vehicle speed coefficient 1 is used to obtain the sensor speed by the above-described equation (4). Using the obtained sensor speed data and the like, the positioning calculation section 23 for autonomous navigation performs positioning calculation of the current position, and after a predetermined time, the processing from step 101 is repeatedly executed.

Since the vehicle speed coefficient is updated by the above processing, the navigation device of this example can improve the accuracy in obtaining the current position by autonomous navigation.
That is, when the vehicle speed coefficient 1 can be updated using the GPS speed data, the sensor speed is calculated based on the vehicle speed coefficient 1 corrected using this GPS speed data, and the sensor speed data is always accurate. Value processing is performed.

When the vehicle speed coefficient 1 based on the short-time average is corrected, the vehicle speed coefficient 2 based on the long-time average is also corrected, and the long-time average value of the vehicle speed coefficient also has accurate data. become.

When the GPS speed data cannot be detected, the updating process for gradually bringing the vehicle speed coefficient 1 closer to the vehicle speed coefficient 2 is performed by the calculation of the equation (5) shown in step 107 of the flowchart of FIG. Then, the processing for obtaining the sensor speed data by the updated vehicle speed coefficient 1 is performed. Therefore, when the period in which the GPS speed data cannot be detected continues for a long time, the sensor speed data is finally calculated by the vehicle speed coefficient 2 based on the long-term average, and the error between the sensor speed data and the actual speed is It is more likely to decrease.

FIG. 4 is a diagram showing a time window in the case of calculating each vehicle speed coefficient 1 and 2 as an average value in the case of the present example. As shown by a solid line in this figure, from a certain past time ta to the present Until time Tb, the time window grows exponentially,
The closer to the present time, the greater the weighting for obtaining the average vehicle speed coefficient. The past time ta differs between the vehicle speed coefficient 1 and the vehicle speed coefficient 2. And COEF1 and COEF
By increasing the value of 2, the change of the time window becomes abrupt as shown by the broken line in FIG. 4, and the weighted average is found toward the current value, and by decreasing the values of COEF1 and COEF2. As shown by the alternate long and short dash line in FIG. 4, the change of the time window becomes gradual, and the average weighted to the past value is obtained.

Here, it will be described with reference to FIG. 5 and FIG. 6 that the error in the sensor speed data is small by setting the vehicle speed coefficient as in this example. Then, when the GPS speed data can be continuously detected, the vehicle speed coefficient 1 changes to the curve S1 shown in FIG. 5, and the vehicle speed coefficient 2 changes to the curve S2 shown in FIG. 5 ( The running state of FIG. 5 is the same as the running state of FIG. 9 described in the conventional example).

Here, during time A to B, GPS
It is assumed that speed data cannot be detected. At this time, in the case of this example, the vehicle speed coefficient 1 changes to the state shown by the curve S3 shown in FIG. The vehicle speed coefficient 1 indicated by the curve S3 matches the curve S1 of the original vehicle speed coefficient 1 until the time A when the GPS speed data can be detected.
When the time A has passed, the curve S2 of the vehicle speed coefficient 2 gradually approaches, and if the GPS speed data cannot be detected for a long time, the curve S2 of the vehicle speed coefficient 2 and the curve S3 come to coincide with each other. Then, when the time B has passed and the GPS speed data can be detected again, the original vehicle speed coefficient 1 is corrected again, so that the curve S3 is the curve S of the original vehicle speed coefficient 1.
It will be equal to 1.

Therefore, the error range Y between times A and B shown in FIG. 6 is a relatively small range, and a vehicle speed coefficient having a smaller error than the error range X shown in FIG. 9 as a conventional example can be obtained. More accurate sensor speed data is calculated when GPS speed data cannot be detected. For this reason, the navigation device of this example is processed so as to minimize the positioning error even when positioning is performed only by autonomous navigation for a long period of time, and more accurate positioning is performed.

In the above embodiment, as the processing for obtaining the vehicle speed coefficient 1 and the vehicle speed coefficient 2, the average is calculated in the time window which changes with an exponential curve as shown in FIG.
You may make it perform another process.

For example, as shown in FIG. 7, when obtaining the average from time ta to time tb, the same time window is set at each time point, and the vehicle speed coefficient 1 and the vehicle speed coefficient 2 are completely averaged.
May be asked. Also, as shown in FIG.
The time window may be linearly widened from the time ta to the time tb. Further, the vehicle speed coefficient 1 which is the short-time average is obtained by the time window increasing with the exponential curve shown in FIG. 4, and the vehicle speed coefficient 2 which is the long-time average is as shown in FIG. 7 or 8. You may make it calculate | require by setting a time window.

Further, when the GPS speed data cannot be detected, the coefficient for obtaining the speed data is switched from the vehicle speed coefficient 1 to the vehicle speed coefficient 2 in the above-mentioned embodiment by the formula [5]. Although the switching is performed by the gradual change based on the indicated value of COEF3, the coefficient for obtaining the speed data may be switched from the vehicle speed coefficient 1 to the vehicle speed coefficient 2 in a shorter time. In this case, for example, the vehicle speed coefficient 1 may be instantaneously switched to the vehicle speed coefficient 2.

In the above embodiment, the vehicle speed coefficient 1 which is the short-time average and the vehicle speed coefficient 2 which is the long-time average are prepared and these two kinds of coefficients are switched. It is also possible to prepare three or more types of vehicle speed coefficients with different detection states and to appropriately select these three or more types of vehicle speed coefficients.

In the above embodiment, the invention is applied to the navigation device using the positioning system called GPS, but it is needless to say that the invention is also applicable to the navigation device in which another positioning system and the positioning system by the autonomous navigation are combined. . Further, the application can be applied to various mobile navigation devices other than the automobile navigation device. However, since the form of the velocity proportional signal obtained by the mounted moving body is different, it is necessary to correspondingly change the processing in the navigation device (count processing by the pulse counter 22 in the above-described embodiment).

[0054]

According to the present invention, it is possible to detect speed information with a small error by selecting a coefficient that seems to be good according to the situation of the moving body and using it for conversion of speed information.
Accurate navigation based on the detected speed information becomes possible.

In this case, as the updating by the coefficient updating means,
Based on the weighting value set for each coefficient, a value between the coefficient value before update and the coefficient value by the newly detected received signal is selected to be the updated coefficient value. Now, it will be updated to a better detection,
More accurate speed information can be detected.

Further, the updating of at least one coefficient in this case is made a weighting value for updating to a value close to the coefficient value by the newly detected received signal in a relatively short time,
By selecting another coefficient as a weighting value that updates the coefficient value close to the coefficient value of the newly detected received signal in a relatively long time, it is possible to select an appropriate coefficient value according to the situation. It will be possible.

Further, by measuring the current position of the moving body based on the speed information thus obtained, it is possible to accurately measure the current position with less error due to autonomous navigation.

Then, the current position thus measured is
By displaying the map on the map displayed on the map display means, the navigation device works well, and good navigation is always possible.

Furthermore, by receiving the signal from the artificial satellite for positioning signal transmission such as GPS and using it as the reference speed signal, the reference speed signal becomes an accurate value, and more accurate. It becomes possible to detect speed information.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing an example of a pulse as a vehicle speed proportional signal according to one embodiment.

FIG. 3 is a flowchart showing a speed correction process according to an embodiment.

FIG. 4 is an explanatory diagram showing a changing state of a time window according to an embodiment.

FIG. 5 is a characteristic diagram showing an example of a change in a vehicle speed coefficient value (when it can be continuously corrected) according to one embodiment.

FIG. 6 is a characteristic diagram showing an example of a change in a vehicle speed coefficient value (when correction cannot be performed between times A and B) according to an embodiment.

FIG. 7 is an explanatory diagram showing a changing state of a time window according to another embodiment of the present invention.

FIG. 8 is an explanatory view showing a changing state of a time window according to still another embodiment of the present invention.

FIG. 9 is a characteristic diagram showing an example of change in a conventional vehicle speed coefficient value.

[Explanation of symbols]

 10 Navigation Device 12 GPS Signal Receiving Unit 13 GPS Positioning Calculation Unit 14 Central Control Unit (CPU) 15 RAM 16 CD-ROM Driver 17 Video Signal Generation Circuit 22 Pulse Counter 23 Autonomous Navigation Positioning Calculation Unit 24 Gyro Device 31 Display Device 32 Pulse generator

Claims (6)

[Claims] 1. In a navigation device mounted on a moving body, at least a converting means for multiplying a speed proportional signal obtained from the moving body by a predetermined coefficient to convert into speed information, and a coefficient for multiplying by the converting means. Two storage means are stored, a positioning signal receiving means, a calculating means for detecting speed information based on a reception state of the positioning signal received by the receiving means, and a speed information based on the receiving signal detected by the calculating means. Based on the above, a navigation device is provided with a coefficient updating means for updating the at least two coefficients in different modes, and a selecting means for selecting a coefficient to be used for conversion by the conversion means. 2. As the updating by the coefficient updating means, a value between the coefficient value before updating and the coefficient value by the newly detected received signal is selected based on the weighting value set for each coefficient. The navigation device according to claim 1, wherein the updated coefficient value is set. 3. The updating of at least one coefficient is set to a weighting value for updating to a value close to the coefficient value by the newly detected received signal in a relatively short time, and the update of another one coefficient is compared. 3. The navigation device according to claim 2, wherein the weighting value is set so as to be updated to a value close to a coefficient value based on a newly detected received signal in a relatively long time. 4. The speed information obtained by the conversion means
The navigation device according to claim 1, wherein the current position of the moving body is measured. 5. The navigation device according to claim 1, wherein the measured current position is displayed on a map displayed on the map display means. 6. The navigation device according to claim 1, wherein the receiving means receives a signal from an artificial satellite for transmitting a positioning signal.