JPH04204111A - Navigation apparatus - Google Patents

Abstract

PURPOSE:To enable precise detection of a position at all times by executing calculation of-the position on the basis of the result of correction of a detected value of an advance azimuth angle by a modified value of an azimuth angle. CONSTITUTION:In an azimuth computation processing element 2, an advance azimuth angle thetac is computed on the basis of detection voltages Vx and Yx inputted from a geomagnetic sensor 1. Next, in an azimuth modification processing element 7, computation is executed on the basis of the azimuth angle thetac supplied from the processing element 2, a signal (f) supplied from a road collation processing element 6 and an azimuth angle thetar of a road, an angle difference thetas between the azimuth angles thetac and thetar is thereby determined and subtracted from the azimuth angle thetac and thereby a true azimuth angle theta is determined. In a distance computation processing element 4, a pulse outputted from a distance sensor 3 is counted and a running distance lfor each unit time is outputted. Then, in the processing element 6, the azimuth angle thetaand the distance l supplied from the processing elements 7 and 4 are processed by computation, the current calculated position of an automobile is collated with a road map read out of a storage circuit 5, the calculated position is thereby corrected and accurate position data are displayed as the current position of the automobile on a map screen.

Description

[Detailed description of the invention]

[INDUSTRIAL APPLICATION FIELD 1] The present invention relates to a navigation device for a car, and more particularly to a navigation device that determines the position of a car from the azimuth angle and travel distance of the car. [Prior art 1] Various types of navigation devices for automobiles have been proposed in the past, but one method is to calculate the position of the automobile sequentially from the direction in which the automobile is traveling and the distance traveled. There is a device that determines the position of the vehicle by comparing the result with road map information stored in a storage device in advance, and an example of this device can be found in Japanese Patent Laid-Open No. 64-3508. By the way, this conventional technology uses a direction sensor that detects the traveling direction of the vehicle from the steering angle of the turning steering wheel of the vehicle.
The control calculation device determines that the vehicle has passed a preset road inflection point and entered a predetermined road, and then drives the vehicle for a predetermined distance with the steering angle of the turning steering wheel in a neutral state. The yaw angle (deviation angle from the traveling direction) at the inflection point was reset and updated to the predetermined road angle mentioned above, thereby preventing the error of the direction sensor from accumulating. . [Problem to be Solved by the Invention] The above-mentioned conventional technology uses a direction sensor that detects the direction of travel of the vehicle from the steering angle of the turning handle of the vehicle. Since this is assumed, there is no consideration given to cases where the steering wheel is almost in the neutral position even on a curved road, such as when driving on an expressway, and the error of the direction sensor is accumulated. There was a problem with being exposed. The object of the present invention is to be independent of changes in the direction of travel of the vehicle;
Moreover, it is an object of the present invention to provide a navigation device that can reliably correct the direction sensor at a sufficiently short frequency and can always accurately determine the position of the vehicle. [Means for solving the problem] In order to achieve the above objective, by comparing the result of calculating the position of the car by the sensor with the road map information, it is possible to determine that the position of the car is on the road indicated on the road map. Each time a determination is made, the sensor is corrected based on the azimuth angle of the road. [Effect] The determination of whether the vehicle's position is on the road marked on the road map by comparing the vehicle's position calculation result by the sensor with the road map information is unrelated to changes in the vehicle's direction of travel. Since the sensor can be corrected frequently, it is possible to maintain high position detection accuracy at all times. To explain in more detail in accordance with the embodiment, the traveling trajectory of the automobile can be determined by successively integrating the detected values of the traveling azimuth and traveling distance at unit time intervals by the azimuth detecting means and the distance detecting means. Therefore, by comparing this driving trajectory with the map, it is possible to know where the car is currently on the map, and as a result, it is possible to know whether the car is driving on the road marked on the map or not. I understand. 22, there is an error in the traveling azimuth by the azimuth detection means,
For example, if the actual heading angle is tilted 10 degrees to the right, it will be necessary to always rotate the travel trajectory by 10 degrees to the right during subsequent verification calculations, which will require extra time. . Furthermore, if you drive on a road that is not marked on the map in this state, when the car returns to the road that is marked on the map, the actual car position and the position determined from the detection results will be displayed. The discrepancy between the two results becomes large and verification becomes difficult. However, in the present invention, since the correction process is executed at a sufficiently high frequency, there is no accumulation of errors, and the verification process can always be performed reliably, making it possible to determine the position with high accuracy.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS A navigation device according to the present invention will be explained in detail below using illustrated embodiments. Fig. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes a geomagnetic sensor for detecting traveling direction, which is called a fluxgate type sensor, and is arranged so that the geomagnetic strengths are orthogonal to each other. The detection voltage of each coil is output as V8, ■. 2 is an azimuth calculation processing unit which inputs the detected voltages V, , VY from the geomagnetic sensor 1, and calculates the traveling azimuth θ as a result of these calculations. It works to output. Here, this traveling azimuth θ. is generally expressed as an angle northward, that is, counterclockwise, with respect to due east. Note that instead of the geomagnetic sensor 1, a combination of some kind of initial orientation setting and angular velocity sensor may be used. 3 is a distance sensor which functions to generate an on10ff pulse every predetermined travel distance according to the rotation of the wheels of the automobile. Reference numeral 4 denotes a distance calculation processing section which functions to count the pulses output from the distance sensor 3 and output the distance traveled per unit time. Reference numeral 5 denotes a memory circuit, which functions to store road map information. Reference numeral 6 denotes a road matching processing section, and a traveling azimuth angle θ supplied from the azimuth calculation processing section 2. Then, the travel distance 1 (L) supplied from the distance calculation processing section 4 is processed to sequentially obtain the travel trajectory from the initial position of the vehicle, and at the same time, the current position of the vehicle is sequentially calculated. The current calculated position is compared with the road map read out from the memory circuit 5, and it is determined whether the position of the car is on the road described in this road map. If it is determined that the car is on the road, then , the calculated position is corrected by comparing the calculated position with the position on the road map, the position is established as an accurate position, and the established position data is supplied to a display device (not shown) and displayed on the map screen. By displaying the current position of the car,
To enable the function as a navigation device to be demonstrated. In addition, in parallel with this, when it is determined that the position of the vehicle is on the road described on the road map as described above, the road matching processing unit 6 also performs a determination that turns on only at that time. It is configured to output the signal f and the azimuth angle θ of the road. Reference numeral 7 denotes an azimuth correction processing section, which receives a traveling azimuth angle θ supplied from the azimuth calculation processing section 2. and the above-mentioned signal f and the azimuth angle θ of the road.
, and first calculate the heading angle θ. The angular difference (corrected angle) O8 between the azimuth angle θ of the road and the azimuth angle θ of the road is obtained, and then this angular difference (corrected angle) O3 is subtracted from the traveling azimuth angle θC to obtain the true azimuth angle θ. Therefore, the calculation process here is as follows. θ, = θ. −θ, ・・・・・・ ・・・・・・(1
) θ = θ. −θ、...su...・・・・・・(
1) Next, the operation of this embodiment will be explained with reference to the flowchart of FIG. 2, focusing on the processing in the orientation correction processing section 7. The process shown in FIG. 2 is sequentially started every time the heading angle θ0 is outputted at a cycle of, for example, 1 second by the calculation process of the azimuth calculation processing unit 2. Referring to the judgment signal f, it is. If it is in the n state, the process proceeds to step 11 and then to step 12, but on the other hand, if it is in the off state, the process immediately proceeds to step 12. First, in step 11, the traveling azimuth θ is determined by the above equation (1). and the azimuth angle θ of the road, the angular difference (correction angle) O8
Perform the process to find . Also, in step 12, the above (
2) Traveling azimuth angle θ shown in equation. A process is performed to obtain the true azimuth angle θ by subtracting the angular difference (corrected angle) θ. Therefore, when the determination result in step 1o is Yes, that is, when the determination signal f is in the On state, step 1
1, the newly calculated angle difference (corrected angle) θ at this point,
The true azimuth θ is calculated by, but when the determination result in step 1o is No, that is, the determination signal f is. ff
In this state, the true azimuth angle θ is calculated from the angular difference (corrected angle) O5 calculated before the previous time. Note that the value of this angle difference (correction angle) θS in the initial state is set to zero. Here, the operating principle of this embodiment will be explained with reference to FIG. First, in this figure, N1 and N2 are road nodes obtained from road map information stored in the storage circuit 5, and a road map is formed by connecting these nodes. Next, reference numeral 81 indicates the current position of the car, which has been determined by the road comparison processing section 6 to be currently traveling on the road, and whose position has been corrected to be on the corresponding road. Further, -Vl indicates a travel vector expressed by the distance traveled in a unit time and the traveling direction at that time, starting from the above-mentioned current position S1 of the vehicle. In addition, the traveling azimuth angle θ. , the azimuth angle θ1 of the road, the true azimuth angle θ, etc. are as described above. In this FIG. 3, the current position S1 is the road nodes N1 and N2.
Since it is on the road indicated by
In the branch judgment based on 0, the car moves to road nodes N1 and N2.
Since it is determined that the vehicle is traveling on the road indicated by , step 11 is executed, and the traveling azimuth θ of the vehicle in the travel vector starting from the current position S1 → v1. An angular difference (correction angle) θ8 between the azimuth angle θ of the road indicated by the road nodes N1 and N2, and the azimuth angle θ8 is calculated. Then, in step 12, the traveling azimuth θ is determined by the above-mentioned equation (2). Since the true azimuth angle θ is obtained by subtracting the angular difference (corrected angle) θ5 from The travel vector →■1 obtained from According to the embodiment, the position of the car is corrected every time it is determined that the position of the car is on the road described on the road map, regardless of changes in the direction of travel of the car. Therefore, it is possible to maintain high position detection accuracy at all times. Next, FIG. 4 shows another embodiment of the present invention, and similarly to the embodiment of FIG. The difference between the embodiment shown in FIG. 4 and the embodiment shown in FIG.
1.22 is only added. After proceeding to step 11 through the branch judgment process in step 1o, the process proceeds to step 21, where the traveling azimuth θ of the vehicle is first determined. The current traveling azimuth θ of the vehicle is selected from memory addresses prepared in advance corresponding to various values of . Select an address corresponding to , and add the angle difference (correction angle) θ calculated in step 11 to that address.
Write 8. Next, in step 22, the traveling azimuth θ of the vehicle is also determined. The address corresponding to the current vehicle heading angle θC is selected from memory addresses prepared in advance corresponding to various values of , and the angular difference (correction angle) θ stored in that address is selected. , and set as the degree difference (correction angle) θ8 in the calculation in step 12. Therefore, according to the embodiment of FIG. 4, the traveling azimuth θ of the vehicle. Since the angular difference (correction angle) θ8 is selected in accordance with the value of It is possible to find the exact driving position. , FIG. 5 shows still another embodiment of the present invention, in which when the branch judgment process in step 10 in the embodiment in FIG. The additional conditions for this include that the vehicle is traveling straight and is on a straight road, and for this reason, steps 31 and 32 are provided between steps 10 and 11. First, in step 31, the traveling azimuth θ is supplied from the azimuth calculation processing section 2. It is determined whether the vehicle is traveling straight or not based on whether the rate of change of is less than a predetermined value, and only when the result is Yes, the process proceeds to step 32, and when the result is No, the process jumps to step 12. Further, in step 32, it is determined from the road map information whether the vehicle is on a straight road or not, and similarly, only when the result is Yes, the process proceeds to step 11, and when the result is No, the process jumps to step 12. Therefore, according to the embodiment shown in FIG. 5, there is no risk that the traveling direction will change during the processing time and the detection accuracy will be lowered, making it possible to determine the position with high precision. Furthermore, FIG. 6 also shows an embodiment of the present invention, and in this embodiment, filtering is applied to the calculation process of the angle difference (corrected angle) θ5. Therefore, the process in the embodiment of FIG. Digital filter processing in steps 41, 42, and 43 is added. First, the angular difference (corrected angle) OS calculated in step 11 is set to 08', and in the subsequent step 41, the angular difference (corrected angle) calculated in the previous process of this angular difference (corrected angle) θ,'θ,' is multiplied by a predetermined filter coefficient k, and this is set as data A. Next, in step 42, the angle difference (
The correction angle) θ,' is multiplied by the complement of the filter coefficient (1-k), and this is set as data B. Then, in step 43, the added value of these data A and B is set as the final angle difference (correction angle) θ5, and step 1
Let's move on to step 2. Note that this filter coefficient takes a numerical value between 0 and 1°0. Therefore, according to the embodiment shown in FIG. 6, there is no possibility that the detected value will change due to noise, etc., sufficiently stable operation can be obtained, and high accuracy can be maintained. [Effects of the Invention] According to the present invention, even if a change in the direction of travel of a vehicle such as a car cannot be detected, the detected value of the traveling azimuth angle can be corrected at a sufficiently high frequency, so that the position can always be determined with sufficient accuracy. can be determined, which can greatly contribute to the safe operation of automobiles. Since the corners are twisted, it produces the effects described below. Further, according to the present invention, once the detected value of the traveling azimuth angle is corrected, the angle of the travel trajectory of the vehicle is determined in one-to-one correspondence with the road angle given from the road map information. This eliminates the need for processing such as rotating the travel trajectory and comparing it with road map information each time a position is calculated, resulting in a significant reduction in calculation processing time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a navigation device according to the present invention, FIG. 2 is a flowchart explaining the operation of an embodiment of the present invention, and FIG. 3 is a diagram explaining the operation of an embodiment of the present invention. 4 is a flow chart explaining the operation of another embodiment of the present invention, FIG. 5 is a flow chart explaining the operation of yet another embodiment of the present invention, and FIG. 6 is a flow chart explaining the operation of yet another embodiment of the present invention. 12 is a flowchart illustrating the operation of another embodiment. 1...Geomagnetic sensor, 2...Direction calculation processing unit, 3...Distance sensor, 4...Distance calculation processing unit, 5...・Memory circuit, 6...
-Road matching processing section, 7... Orientation correction processing section.

Claims (4)

[Claims] 1. The position of the car was calculated based on the detected traveling azimuth of the car outputted from the azimuth detection means and the detected travel distance of the car outputted from the distance detection means, and the calculation result of this position was read out from the storage means. A navigation device that determines the location of a vehicle by comparing it with road map information, comprising: a determining means for determining whether the location of the vehicle is within a road included in the road map information; arithmetic processing means for sequentially detecting an angular difference between the traveling azimuth detection value and the azimuth of the road as an azimuth angle correction value on the condition that the determination result by the means is positive;
A navigation device characterized in that the position is calculated based on the correction result of the detected traveling azimuth angle by the azimuth correction value. 2. In the invention of claim 1, each time the azimuth angle correction value is detected, the azimuth angle correction value is classified and sequentially stored in a storage area corresponding to the detected traveling azimuth angle of the vehicle at that time. A storage means is provided in which the traveling azimuth angle detection value is corrected by the azimuth angle correction value based on the azimuth angle correction value read from the storage area corresponding to the traveling azimuth detection value at that time. A navigation device comprising: 3. In the invention of claim 1, the determining means determines whether the vehicle is traveling straight and the position of the vehicle is within a straight road among the roads included in the road map information. A navigation device characterized by comprising means. 4. In the invention of claim 1, the arithmetic processing means comprises 1
A navigation device characterized in that the navigation device is configured to sequentially detect the orientation correction value through the following digital filter processing.