JPS58135911A - Error compensating device for navigation system for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an error correction device for a vehicle navigation system, and more particularly to an error correction device that corrects a detection error of an azimuth sensor that detects the direction of travel of a vehicle and allows the navigation system to correctly display the travel position of the vehicle.

In recent years, vehicles equipped with navigation systems that display the driving position of the wheels on a CRT in real time have been put into practical use, allowing drivers to instantly determine the distance to their destination from the vehicle driving position displayed on the CRT. This is especially convenient when driving long distances.

Such a navigation system usually uses a direction sensor that detects the direction of travel of the vehicle, and performs CR based on the direction of travel of the vehicle detected by the direction sensor.

The vehicle's driving position is displayed on the T. Therefore, in order for the navigation system to operate accurately, it is a prerequisite that the vehicle traveling direction detected by the orientation sensor O is accurate.

In this sophisticated navigation system, there are several types of azimuth sensors that detect the direction of vehicle travel, such as those that use a gyro and those that use geomagnetism. Among these, the type of orientation sensor that uses geomagnetism detects weak geomagnetism, so if the vehicle body becomes magnetized, an error occurs in the detected wheel running direction.

Vehicles equipped with navigation systems that use geomagnetic type orientation sensors are usually demagnetized at the factory to prevent this error from occurring, but the width of the vehicle is often exposed to strong electromagnetic fields from outside while driving. In addition, when a permanent magnet fixed type ham antenna or the like is attached to a vehicle, the magnetic field generated by the vehicle gradually becomes magnetized, making it difficult to prevent the above-mentioned error from occurring. Therefore, as the error in detecting the running direction of the vehicle by the azimuth sensor due to the magnetization of the vehicle increases, the error in the wheel running position displayed on the CRT also increases, and a countermeasure for this problem has been desired. ,' The present invention has been made in view of such conventional problems, and its purpose is to accurately determine the detection error of a geomagnetic type orientation sensor, and to easily and accurately correct the WA difference. An object of the present invention is to provide an error correction device for a vehicle navigation system that can correctly display wheel running positions on a CRT.

To achieve this object, the device of the present invention includes a direction sensor that detects the direction of vehicle travel based on geomagnetism, and displays the vehicle's travel position on a CRT based on the direction of vehicle travel detected by the direction sensor. In the navigation system, there is a reference pattern display device that displays the omnidirectional detection reference pattern of the orientation sensor in the non-magnetized state of the vehicle on the CRTJ: and displays the omnidirectional detection pattern that the orientation sensor actually outputs on the CRTJ. A detection pattern display device that indicates the detection error of the orientation sensor based on the magnetization of the vehicle main body based on the positional deviation from the reference pattern, and a detection pattern display device that displays the detection error of the orientation sensor based on the magnetization of the vehicle main body by correcting the positional deviation of the two patterns displayed on the CRT. The present invention is characterized by comprising a correction device that corrects a detection error of the orientation sensor based on magnetization.

Next, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a wheel navigation system, in which a microcomputer 14 processes the wheel running direction detected by the orientation sensor 1O and the vehicle speed detected by the vehicle speed sensor 12, The vehicle position is displayed in real time on a CRT 16 attached to a console box or the like. Therefore, the driver can instantly determine the current location and the distance to the destination from the correlation between the map displayed on the CRT 16 and the vehicle travel position.

By the way, it is necessary to appropriately display a map of the area in which the vehicle is traveling on the CRTt6. For this reason, the system of the embodiment includes a cassette deck 18, and reads map information from a cassette tape on which predetermined map information is recorded.

The information thus read using the cassette deck 18 is input into the microcomputer 14 via the cassette interface 20, and further written and stored in the RAM 24 via the Ilo interface 22.

Since approximately 200 pieces of map information are usually recorded on a commercially available cassette tape (C-60), by reading the above-mentioned map information, the map information for several pieces is stored in the RAM 24. Become.

Therefore, if the driver performs predetermined key operations on various keys arranged on the keyboard 26 and instructs the microcomputer 14 to display unnecessary map information as appropriate via the I10 interface 28, the microcomputer 14
reads necessary information from the RAM 24 and controls the CRT controller 30 to display a map on the CRT 16 as shown in FIG.

In order to display the wheel running position on the map displayed on the CRT 16 in this manner, it is necessary to set a starting point as an initial condition. To do this, set the cursor A that appears on the CRT 16 to the starting point by performing predetermined key operations on the keyboard 26. When you drive the vehicle after configuring the settings,
The microcomputer 14 receives the vehicle traveling direction detected by the orientation sensor IO via the orientation sensor up 32, and the vehicle traveling speed detected by the vehicle speed sensor 12 via the I10 interface 28. is input. Then, the microcomputer 14 performs predetermined arithmetic processing on the input vehicle running direction and vehicle running speed to calculate the vehicle running position, and this running position is transferred to the CRT1.
6.

FIG. 3 shows the azimuth sensor 10 shown in FIG. 1, and in the embodiment, a azimuth sensor that detects the direction of vehicle travel based on earth's magnetism is used. FIG. 4 shows an electrical circuit diagram of the main parts of the present invention including the orientation sensor IO.

The orientation sensor lO of the embodiment is formed by winding an X-axis coil lOb and a Y-axis coil IOC around a permalloy ring 10a so as to be electrically orthogonal to each other, and further wrapping an excitation coil 10d around the permalloy ring 10a. . A predetermined alternating current voltage is applied to the excitation coil 10d from the excitation drive circuit 32a to generate alternating electromagnetic flux within the perm ring 10a.

The orientation sensor 10 is attached to a predetermined part of the vehicle, for example, the roof, and outputs a terminal voltage corresponding to the vehicle running direction to the 6x-axis coil terminal and the Y-axis coil terminal by the earth's magnetism interlinked with each coil 10b and IOc.

In other words, since the direction and strength of the earth's magnetic field are constant,
There is a certain correlation between the effective linkage of the earth's magnetic field to each of the coils lOb and 10C of the orientation sensor 10 and the direction in which the vehicle is traveling. Therefore, if you measure the relationship between the voltage output from each coil 10b and IOC terminal and the vehicle running direction in advance,
The vehicle running direction can be immediately detected from the voltage output from each coil 10b, 10c terminal.

Note that when the vehicle main body is magnetized, such a direction sensor 1O causes an error in detecting the vehicle running direction, and as a result, the CRT1
Errors also occur in the wheel running positions displayed on 6. Is this invention a direction sensor? The system corrects such detection errors that occur in the sensor 10 and displays the vehicle traveling position correctly on the CRT 15, and uses the omnidirectional detection reference pattern and the omnidirectional detection pattern output by the direction sensor IO to correct the error. It is carried out in The details will be explained below.

The omnidirectional detection reference pattern of the orientation sensor 10 is a coordinate pattern obtained from the orientation sensor 1o when the vehicle body is in a non-magnetized state.
The voltages output from the X-axis coil 10b and the Xy-axis coil IOc when rotated 600 times are plotted on the X-Y coordinate axes.

Since the orientation sensor 1o of the embodiment is wound around the ring lQa so that the Fix-axis coil lob and the Y-axis coil loc are perpendicular to each other, the omnidirectional detection reference pattern is biased by the common voltage of the Fix-axis coil lQb and the Y-axis coil 10e. It becomes a perfect circle centered at the voltage.

Therefore, when the orientation sensor 10 is attached to the vehicle body in a completely demagnetized state and the orientation sensor 10 is horizontally rotated 3606 times, its X-axis coil iob.

The gain and origin adjustment circuit 36 adjusts the gain of the voltage output from the Y-axis coil loc, and then the A/D converter 3
8 and plotted on the X-Y coordinates, an omnidirectional detection reference pattern consisting of a perfect circle centered on the common voltages Xc and Ye of the X-axis coil 1Ob and Y-axis coil IOc is obtained, as shown in FIG. 100 is obtained.

The omnidirectional detection reference pattern 100 obtained in this way is stored in the ROM 34.

Assuming that the radius of this reference pattern 100 is R, in the embodiment, when the vehicle traveling direction is east, each of these coils lO
b, the voltage obtained from 10C is (X, + R%Yc
), when the vehicle traveling direction is north, each of these coils 10b,
The direction sensor 10 is attached to the vehicle body so that the voltage obtained from the direction sensor 10c is (Xc1Yc+R).

Therefore, if the voltage obtained from each coil 10b and IOC of the direction sensor 10 is at point P (X% Y) in FIG. That is understood.

In this way, the computer 14 detects the running direction of the vehicle, but this detection method is based on the omnidirectional detection result (center of turn and ROM 34 This is done on the premise that the centers of the omnidirectional detection reference patterns 100 stored in the memory coincide with each other.

However, since the omnidirectional detection reference pattern 100 stored in the ROM 34 is created based on a state in which the vehicle body is not magnetized, when the vehicle body is magnetized, the direction sensor lO The center of the omnidirectional detection pattern 200 that is actually output is shifted by (X1 and Y) compared to the reference detection pattern 100. This is because when the vehicle body is magnetized, the magnetic flux emitted from the vehicle body influences the true geomagnetic component. □゛□・ In this way, the omnidirectional detection pattern 200 actually output by the direction sensor 10 is compared to the reference number (turn 100).
X, jY), the true wheel running direction θ is as follows.However, the computer 14 changes the wheel running direction to the (1st
) is calculated based on the formula. Therefore, the vehicle running direction calculated by the computer 14 is θ with respect to the true vehicle width running direction θ', and an error of (0'-0) occurs between the two.

Since a vehicle equipped with a general navigation system is demagnetized at the time of shipment from the factory, such a detection error by the direction sensor 10 does not occur at the time of purchase.

However, the vehicle body is gradually magnetized by a permanent magnet fixed antenna attached to the roof or the like, and is also magnetized by driving in a strong electromagnetic field. Therefore, as time passes from the time of purchase, the wheel body becomes gradually magnetized, causing the above-mentioned detection error of the orientation sensor IO.

The characteristic feature of the present invention is that the reference pattern 1 is printed on the CRT 16.
00 and the omnidirectional detection pattern 200 actually output by the orientation sensor lO, and align the centers of both patterns 100 and 200. , θ' are made to match, and the error correction of the orientation sensor lO is performed.

An azimuth sensor origin calibration switch 26a for instructing such error correction is provided on the keyboard 26, and by operating the switch 26a, the computer 14
The reference pattern display device 40 and the detection pattern display device 42 included in the display are driven.

By operating the reference pattern display device 4 (lt, switch 261), the omnidirectional detection reference pattern 100 stored in the fiROM 34 is displayed on the CRT 15.

In the embodiment, in order to facilitate the correction operation described later, the reference pattern 100 is displayed with a constant width of an inner diameter r1 and an outer diameter rb, as shown in FIG.

The detection pattern display device 42Fi displays on the CRT 16 the omnidirectional detection pattern 200 that the direction sensor 10 actually outputs when the swing f26a is operated.
Ku. The omnidirectional detection pattern 200 actually output by the direction sensor 1O is obtained by horizontally rotating the direction sensor 10 mounted on the vehicle body 3606 times, and during the rotation, the X-axis coil xObx
The voltage output from the Y-axis coil IOc is stored and displayed as shown in FIG.

In the embodiment, since the orientation sensor 10 is fixed to the vehicle body, it is necessary to rotate the vehicle around in order to horizontally rotate the orientation sensor 10 by 360@.

When the reference pattern 100 and the omnidirectional detection pattern 200 are displayed on the CRT 16 as shown in FIG.
The detection error of the azimuth sensor 10 can be confirmed by the positional deviation.

Therefore, by correcting the positional deviation of both patterns ion and 200 displayed on the CRT 16 in this manner, it is possible to correct the detection error of the orientation sensor 10 based on the magnetization of the vehicle body.

In the embodiment, the X origin adjustment volume 44, the X origin adjustment volume 46, and the gain and origin adjustment circuit 36 provided on the keyboard 26 form a correction device that performs the above correction.

That is, the gain and origin adjustment circuit 36 is the adjustment button 1):
A bias voltage corresponding to the operation amount of x--A44.46 is superimposed on the voltage output from the X-axis coil xOb and Y-axis coil IOc of the orientation sensor 10.

Therefore, a person who intends to perform the correction should check the reference pattern 100 of the omnidirectional detection pattern 200 from the display on the CRT 15.
The amount of positional deviation for each adjustment volume 44.
46, a bias voltage for offsetting the amount of positional deviation is superimposed on the output of the azimuth sensor 10. As a result, the omnidirectional detection pattern 200#i is corrected to match the reference pattern 100.

Note that in reality, the omnidirectional detection pattern 200 output by the orientation sensor IO is not a perfect circle and has distortion, so it is difficult to determine how closely the omnidirectional detection pattern 200 matches the reference pattern 100 just from the display on the CRT 16. If so, it is difficult to judge whether the detection error of the orientation sensor 1o falls within the allowable value. In the embodiment, the reference pattern 100 is
Since a is displayed with a constant width of the outer diameter r-, if this inner diameter r and outer diameter rb are set within the allowable error range,
The omnidirectional detection pattern 200 may be corrected so that it falls within the range between the inner diameter r and the outer diameter rb. Thereby, the correction operation can be performed quickly and easily, and the correction of the orientation sensor 10 is performed accurately so that the detection error is within an allowable range.

In the apparatus of the embodiment, the inner diameter r and outer diameter rb of the reference pattern loo displayed on the CRT 16 are adjusted to arbitrary values by key operations on the keyboard 26.

The present invention has the above-mentioned configuration, and its operation will now be explained based on the flowchart shown in FIG.

The device of the present invention is used to correct the error when the error in the vehicle running direction detected by the orientation sensor 10 becomes large and the error in the wheel running position displayed on the CRT 6 becomes large.

First, the calibration switch 2 installed on the keyboard 26
When 6a is operated, the reference pattern display device v140 and the detected pattern display device 42 included in the computer 14 are displayed.
is driven, and the reference pattern display device 40tiCRT16
As shown in FIG. 8 above, the reference pattern 100 is displayed, as well as characters explaining the subsequent correction procedure.

When the display shown in FIG. 8 is displayed on the CRT 16, the person performing the correction rotates the wheel 36 (]'' in accordance with the correction procedure displayed on the CRTi 6.Detected pattern display device 42
When the U vehicle goes around, the voltages of the X-axis coil 10b and Y-axis coil 10c output from the azimuth sensor 10 are read, and the omnidirectional detection pattern 200 of the azimuth sensor IO obtained from this reading is as shown in FIG. <Display on CRTx6.

It is necessary to perform the circling motion of the vehicle in a place where there are no high-voltage lines, magnetic materials, motors, or other objects that disturb the earth's magnetic field. This is because the distortion of the omnidirectional detection pattern 200 obtained from the orientation sensor 10 becomes large.

The person performing the correction from the display on the CRT 16 thus made determines the amount of correction of the omnidirectional detection pattern 200 with respect to the reference pattern 100, and adjusts the adjustment volume 44.
6 is used to perform error correction. That is, by operating the adjustment volume 44 or 46 according to the correction amount of the omnidirectional detection pattern 200 determined from the display on the CRT 16, the voltage output from the X-axis coil 1obs and the Y-axis coil IOC will be adjusted to a predetermined value by the gain and origin adjustment circuit 36. bias voltage is superimposed. As a result, the omnidirectional detection pattern 200 actually output by the orientation sensor IO is corrected from the position shown by the solid line 200 in FIG.

The person performing the correction judges from the display on C) tT1g whether or not the error correction has been made properly, and if it is judged that it has been done properly, turns off the calibration switch 26a and ends the error correction operation.

When the error of the azimuth sensor 10 is corrected in this way, the navigation system can accurately display the vehicle running position on the CRT 16 based on the vehicle running direction detected by the azimuth sensor 10.

As explained above, according to the present invention, it is possible to accurately determine the detection error of the vehicle running direction that occurs in the direction sensor due to the magnetization of the vehicle body based on the display on the CRT, and furthermore, the error correction can be performed on the CRT. This can be done easily and accurately based on the display.

Therefore, even if the vehicle body is magnetized, it is possible to always accurately display the vehicle traveling position on the CRT), and as vehicle navigation systems are put into practical use, their effectiveness will be very large.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the navigation system, Figure 2 is an explanatory diagram of the image displayed on the CRT in Figure 1, Figure 3 is an explanatory diagram of the structure of the orientation sensor shown in Figure 1, and Figure 4 is an illustration of the structure of the orientation sensor shown in Figure 1. 5 and 6 are explanatory diagrams of the omnidirectional detection reference pattern and the omnidirectional detection pattern of the azimuth sensor, and FIG. Flowcharts showing the operation of the invention, FIGS. 8 and 9 are images displayed on a CRT. lO... Orientation sensor, 16... CRT. 40... Reference pattern display device, 42... Detected pattern display device, 36.44.46... Gain and origin adjustment circuit constituting the correction device, X-axis adjustment volume, X-axis adjustment volume, 100... - Omnidirectional detection reference pattern, 200... Omnidirectional detection pattern. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 73- Figure 8 Figure 9

Claims (1)

[Claims] (1) A vehicle navigation system that includes a direction sensor that detects the direction of vehicle travel based on geomagnetism and displays the vehicle's travel position on a CRT based on the vehicle travel direction detected by the direction sensor, A reference pattern display device that displays an omnidirectional detection reference pattern of the orientation sensor in a magnetized state on a CRT; and a reference pattern display device that displays an omnidirectional detection pattern that the orientation sensor actually outputs on the CRT, and displays the omnidirectional detection pattern that the orientation sensor actually outputs on the CRT; a detection pattern display device representing a detection error of the orientation sensor based on the magnetization of the width body;
An error correction device for correcting a detection error of a direction sensor based on magnetization of a vehicle body by correcting a positional deviation between the two patterns displayed on a CRT. correction device.