JPS63177016A - Navigation apparatus of car - Google Patents

Abstract

PURPOSE:To keep the confirmation accuracy of the present position as high as possible, by confirming the present position of a vehicle by utilizing GPS and prohibiting the confirmation of the present position of the vehicle utilizing GPS when a receiving state is deteriorated. CONSTITUTION:A satellite utilizing azimuth measuring apparatus 1, an earth magnetism utilizing azimuth measuring apparatus 2 and a present position confirming means composed of a change-over apparatus 4 for selecting the measuring data of either one of both apparatuses 1, 2 are mounted on board and the present position of a vehicle is confirmed. A receiving state detection means 5 for detecting deterioration coefficient and electric field intensity is connected to the apparatus 1. When the means 3 detects that the deterioration coefficient (or the electric field intensity) is equal to or more than (or less than) a predetermined value, it is stopped that the position signal from the apparatus 1 is outputted to an induction apparatus 5 and a position signal to be used is changed over from the apparatus 1 to the apparatus 2. Therefore, the confirmation of the present position by the use of the measuring data of a measuring means having high measuring accuracy can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a navigation device for an automobile, and particularly to a navigation device equipped with a current position recognition means that receives radio waves from a satellite and recognizes the current position of the vehicle. It is something.

(Prior art) As an automobile navigation system 2, for example, Japanese Patent Laid-Open No. 5
As disclosed in Japanese Patent No. 8-70117, a vehicle is known that displays the current location of the vehicle and a map of its surroundings on the screen of a display device to provide driving guidance.

As means for recognizing the current position of a vehicle in such a navigation device, one using a direction sensor such as a geomagnetic sensor has already been put into practical use.

That is, the vehicle speed sensor and the azimuth C sensor detect the vehicle's travel route 1III1 and the azimuth from a certain reference point, thereby recognizing the current position of the vehicle. However, with such conventional current position recognition means, the current position of the vehicle is, so to speak,
Since the position is measured relative to a reference point, accuracy decreases due to measurement errors in travel distance and direction.

Therefore, it is conceivable to measure the current position of the vehicle as an absolute position using radio waves emitted from a satellite. For example, the global positioning satellite system currently under development (
G lobal positionin.

It is conceivable to measure the current position of the vehicle as an absolute position using GPS (hereinafter referred to as GPS). This GPS is capable of measuring the current position of a vehicle with a positioning accuracy of approximately 30 meters based on radio waves emitted from four artificial satellites (called NAVSTAR) (C) which is open to the general public. /A code)
.

(Problems to be Solved by the Invention) However, in such a system, the reception condition may deteriorate or reception may become impossible depending on the position of each satellite or reception obstacles on the ground. For example, when a vehicle travels through a tunnel, it may become impossible to receive radio waves from an artificial satellite. As described above, when recognizing the current position of a vehicle using GPS, if the reception condition is good, the recognition accuracy is very high, but if the reception condition deteriorates, the recognition accuracy decreases significantly.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an automobile navigation device that can maintain the recognition M degree of the current position as high as possible when recognizing the current position of the vehicle. It is something to do.

(Means for Solving the Problems) The automobile navigation device according to the present invention recognizes the current position of the vehicle using GPS and other positioning means, and when the reception condition deteriorates, the vehicle navigation device uses GPS to recognize the current position of the vehicle. The above objective is achieved by prohibiting current position recognition, and the deterioration coefficient and electric field strength are used as criteria for determining whether the reception condition is good or bad. That is, as shown in Figure 1,
A satellite-based positioning means (a) that receives radio waves from a satellite and measures the current position of the vehicle; and another positioning means (b) that measures the current position of the vehicle; Current position recognition means (C) that recognizes the current position of the vehicle based on positioning data; Reception state detection means (d) that detects a deterioration coefficient and electric field strength based on radio waves from the Wi star; and this reception state detection means. Prohibition means (e
).

The above 1 deterioration coefficient J (Geometrical (
)Ilution Or Precision (abbreviated as GDOP) is the geometric relationship between the satellite used during positioning and the positioning point (in this case, the vehicle), that is, the positioning determined by the placement of the satellite used with respect to the vehicle. This is a coefficient representing an increase in error.

Examples of the above-mentioned "other positioning means" include those using a direction sensor such as a geomagnetic sensor, and those using a gas rate sensor, but it is needless to say that they are not limited to these. “The other positioning means J may be singular or plural.

(Function) If the deterioration coefficient calculated from the satellite placement status exceeds a predetermined value, the accuracy of positioning the current position will decrease, and if the strength of the radio waves from the satellite, that is, the electric field strength, falls below the predetermined value, the relationship between the satellite and the vehicle will deteriorate. It can be assumed that there is an obstruction between them, and in such a case, the positioning accuracy of the current position will decrease, but as shown in the above configuration, the reception condition has deteriorated to below a predetermined level based on the deterioration coefficient and electric field strength. When it is detected that the current position of the vehicle is recognized based on the positioning data of the satellite-based positioning means, recognition of the current position of the vehicle based on the positioning data of the satellite-based positioning means is prohibited. It is also possible to avoid situations where the current location cannot be recognized. In other words, if the vehicle's current position is being measured using a satellite-based positioning method during a prohibited direct turn, the system automatically or manually switches to another positioning method with relatively higher positioning accuracy. On the other hand,
If the current position of the vehicle was measured using another positioning method immediately before the ban, the current position may be recognized by switching to a satellite-based positioning method with lower positioning accuracy. This makes it possible to prevent situations from occurring.

(Effects of the Invention) Therefore, according to the present invention, the recognition accuracy of the current position of the vehicle can be maintained as high as possible within the selectable range, thereby improving the marketability of the navigation device. can.

(Examples) Examples of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is an overall configuration diagram showing an embodiment of an automobile navigation device according to the present invention.

The navigation device includes a satellite positioning device 1 which is a satellite positioning means, and a geomagnetic positioning device 2 which is another positioning means.
and current position recognition means consisting of a switching device 4 that selects positioning data from either of these two positioning devices 1.2,
This current position 1 means recognizes the current position of the vehicle.

The satellite-based positioning device 1 includes, for example, 18 to 21 satellite-based positioning devices controlled by a ground main control station 1a via, for example, four ground antennas 1b, which are appropriately distributed in a GPS system as schematically shown in FIG. Of the satellites, the receivable area (field of view)
It constitutes the user part of the GPS that measures the current position of the vehicle based on radio waves transmitted from four of the satellites 81 to S4.

The positioning accuracy of this satellite-based positioning device 1 is the position of WIu,
It is known that positioning accuracy may decrease due to perturbations of VH stars, the state of the ionosphere, etc., or that positioning may become impossible in some areas, albeit for a very short time.

It is also known that receiving necessary radio waves becomes difficult or impossible due to obstacles on the ground, such as when driving in a tunnel.

The degree of decrease in positioning accuracy in satellite-based positioning device M1 is as follows:
It varies depending on the deterioration coefficient and electric field strength. Of course, the deterioration coefficient is a value determined by the geometric relationship between the satellite used during positioning and the vehicle, and as the deterioration coefficient increases, the positioning error also increases and the positioning accuracy decreases. Other factors that cause the positioning accuracy to decrease appear as a decrease in electric field strength. Then, when the deterioration coefficient becomes greater than or equal to a predetermined value or the electric field strength becomes less than or equal to a predetermined value, the positioning error exceeds the allowable value ω.

For this reason, the satellite-based positioning device 1 is connected to reception state detection means 3 that detects the deterioration coefficient and electric field strength. The deterioration coefficient can be determined from the position data of the satellites used during positioning, which is transmitted from each satellite based on the tracking results of the satellite by the ground antenna 16 and the data received by the ground monitor station 1C. This is possible, and the electric field strength can be detected by the strength of radio waves received from the satellite.

In addition, a satellite-based positioning device 1 and a geomagnetism-based positioning device 2
A switching device 4 is connected to. This switching percentage position 4 is
The position signal output by the satellite-based positioning device 1 and the position signal output by the geomagnetism-based positioning device 2 are input, and among both signals, the signal from the satellite-based positioning device 1 is prioritized and output to the guidance means 5, which will be described later. It looks like this. The switching device 4 is also connected to the reception state detection means 3,
When it is detected that the reception state detection means 31Z b' is greater than or equal to a predetermined value or that the electric field strength is less than or equal to a predetermined value, the position signal from the satellite-based positioning device W11 is transmitted to the guidance means 5.
The position signal used is switched from that of the satellite-based positioning device @1 to that of the geomagnetism-based positioning device M2.

That is, when the positioning error by the satellite-based positioning device 1 is within a predetermined range, the position signal of the satellite-based positioning device 1 is selected, and when the positioning error exceeds the predetermined range, the switching device 4, which is a prohibition means, selects the position signal of the satellite-based positioning device 1. At the same time as the use of the position signal of the positioning device 1 is prohibited, the position signal of the geomagnetic positioning device 2 is selected, and the position signal selected by the switching device 4 guides the vehicle to travel based on this position signal. It is configured to be outputted to the guiding means 5.

The guidance means 5 has a video screen whose surface is covered with a transparent matrix switch, for example, and displays the destination and the current position of the vehicle on a map displayed on the screen, and allows the driver to navigate from the current position to the destination. The vehicle is configured to guide the vehicle by providing directions, direction, travel distance, etc.

Note that it is of course possible to use a known configuration for the guiding means 5.

The principle of positioning using GPS is as follows.

In other words, if there is a clock that is perfectly synchronized at the transmitting point and receiving point of radio waves, and the transmitted signal is controlled by that clock, then if you measure the timing of reception at the receiving point, you can calculate the propagation time of the radio wave between the transmitting and receiving points. By multiplying it by the speed of light, the distance between the transmitting and receiving points can be determined.

Now, as shown in Figure 4, there are three satellites S1, S2, and S3 in the user's field of view (receivable area), and each satellite S1, S2, and S3 receives ranging signals using synchronized clocks. Suppose you are sending. By measuring the reception time of these signals at the receiving point P, the distance between each WI star S1, S2, S3 and the receiving point 2 can be found, and the receiving point P is the distance between each satellite 81, 82, 8.
It can be found as the intersection of three spherical surfaces centered at 3. However, synchronizing the clock at the receiving point P with that at the transmitting point is not only technically problematic, but also disadvantageous in terms of making the receiver inexpensive. This problem is solved by increasing the number of satellites receiving the signal by one more.

FIG. 4 shows this in a two-dimensional manner for easy understanding. If the clock at the receiving point is behind the clock on each satellite by △tu, the radius of the three measured circles will be larger than the actual one by △tuc (c is the speed of light), which means that it should be one point. The three circles that should intersect no longer intersect (
solid line diagram). △tuc so that these three circles intersect at one point
By adjusting the value of △tu at the same time as the position of receiving point P,
can also be found. In this way, GPS stores a fixed value for satellite i as a pseudo distance. The pseudorange R1 to the satellite i is R1-R1+c△tai+c (△tu-△tsvi
). Here, △tai is a in the ionosphere and troposphere.
3 Gj radio wave delay time, Δtsvi, is the time offset of the clock of satellite i. Instead of synchronizing each other, the atomic clocks on the satellite measure their offset values, make predictions, and transmit the value of Δtsvi from the satellite in a form that can be calculated. To perform three-dimensional positioning, it is possible to solve a total of four unknowns, three position coordinates and ΔtU, using 1llll constant values of four pseudoranges for the four satellites i=1 to 4.

Similarly, a measurement of the Doppler frequency, or pseudorange rate of change, of the signal from the satellite can be used to measure the user's three-dimensional velocity.

In addition, when determining the user's position based on the satellite position, the user must know the position of the satellite and the status of the clock on the satellite W, which change from time to time, and these data are also tJli is transmitted from the satellite.

Each satellite is equipped with a receiving circuit (not shown) and a transmitting circuit 10 (not shown in FIG. 5) for receiving radio waves transmitted from the main control station 1a via the ground antenna 1b.

This transmitting circuit 10 includes a reference frequency oscillation circuit 11 that outputs a reference frequency signal of, for example, 10.23 MHz, and an L+ carrier wave which is a first carrier wave by multiplying the frequency of the reference frequency signal to be outputted by 154 times. (1575,4
2MH2), and a multiplier 13 that multiplies the frequency of the reference frequency signal by 120 times to form an L2 carrier wave (1227,6MHZ), which is a second carrier wave.
It has The transmitting circuit 10 also includes a clock forming circuit 14 that forms a clock signal of a predetermined period from a reference frequency signal, and two signals called P code and C/A code as ranging signals from the reference frequency signal and this clock signal.
The computer 16 has a code generation circuit 15 that generates various code signals, and a computer 16 whose timing is controlled by the clock signal and outputs data regarding the position of the satellite and the state of the clock on the satellite, which changes from time to time. The P code is a highly accurate and secret code that can only be used by the military and specially authorized users. After being superimposed with the data output from the computer 16, it is used to orthogonally modulate the first and second carrier waves as described above. sent with a repetition rate of 10.23
Mbit/s This is a long code whose length lasts 1'ij4. The C/A code is used for coarse positioning (8! quasi-positioning) and P code capture, and is a code that is open to the public. This C/A coat signal is superimposed with data output from the computer 16, and then transmitted in the form of modulating both Ls and 12 carrier waves, with a repetition rate of 1.023.
M bit/s, the length is 1,023 bits, or repeated every 11S. It should be noted that the C/A code generation circuit is constituted by, for example, a gold code generation circuit using two 10-stage shift registers. The data output by the computer 16 is measured and predicted by a control section on the ground, stored in a storage circuit (not shown) of the satellite, and sequentially read out. These data are for example 5
It is transmitted at a predetermined timing at a transmission rate of 0 bit/s. This data includes telemeter language, handover language, ionospheric correction parameters, single-frequency receiver delay correction, clock correction data era, clock correction reference time, GPS system time, orbit prediction era, and orbit elements. reference time, average periapsis angle at orbital element reference time, eccentricity, square root of semimajor axis, ascending node right ascension, orbit a inclination, perigee argument, ascending node perturbation, mean motion correction, inclination correction It includes data such as parameters for use in the satellite, correction terms for orbit disturbances, satellite identification numbers, reference times for data subframes, and the health status of the satellite. In addition, it is possible to predict the period during which the user's receiver can receive signals from each satellite, select the combination of satellites in the field of view that will give the highest positioning accuracy, and acquire the signals from the satellites as quickly as possible. The almanacs (almanacs) of other satellites belonging to the system can be used to pre-configure the receiving circuit.
manac) data is also included.

The above control section includes a main control station 1a, a ground antenna 1b placed at multiple fixed points on the ground (4 or more locations are planned), and a ground antenna 1b located at multiple fixed points on the ground (4 or more locations are planned). It has a monitor station 1C arranged therein. Lord fII
The lIII station 1a tracks the satellite via the ground antenna 1b, predicts the clock on the satellite and the orbit of the satellite according to the results, and transmits data for putting them into the memory of the satellite so that they can be broadcast from the satellite. It is a manned facility equipped with a large computer and a series of operational control vehicles. The monitor station 1C is an unmanned station equipped with a receiver for signals from a satellite, an atomic clock, and a meteorological side instrument for calculating tropospheric delays.

As shown in FIG. 2, the satellite-based positioning device 1, which is the user part, includes a receiver 6 that receives signals from a desired satellite, measures the current position of the vehicle from the received signal, and determines the position corresponding to the current position. It has a signal processing means 7 that outputs a signal. Further, as shown in FIG. 6, the satellite-based positioning device H1 includes a crystal excavator 8 that outputs a reference frequency signal that is an overall timing control signal, and an operation timing of the signal processing means 7 based on this reference frequency signal. The receiver 6 includes a clock oscillation circuit 9 that generates a clock signal for controlling the receiver 6, and an antenna 11, a preamplifier 18, and a bandpass filter 19 connected to the front stage of the receiver 6.

The receiver 6 is a frequency synthesizer that creates a signal with the same pattern as the carrier wave of the satellite's transmitter 10 and the data that intersects with the position of the satellite and the state of the clock on the display based on the reference frequency signal oscillated by the crystal excavator 8. a circuit 61, a code generation circuit 62 which inputs the clock signal output from the clock oscillation circuit 9 and forms a code signal having the same pattern as the ranging signal, and output signals of the frequency synthesis circuit 61 and the code signal generation circuit 62. The time 81 on Weikun, the data regarding the orbit of the satellite, the data and carrier wave detector 63 for correlation detection of the carrier wave, and the code generation circuit 6
It has a code lock detector 64 that performs correlation detection on the distance measurement signal using the code signal outputted by the sensor 2.

Further, the timing of the signal processing means 7 is controlled by a clock signal output from a clock oscillation circuit 9.

Although FIG. 6 shows the receiver 6 with one reception channel, two reception channels are provided, and the first reception channel is used to sequentially switch and receive signals from four satellites within the field of view. and the second receiving channel is dedicated to each I! It will be used to acquire broadcast data from Star J and preliminary capture of signals from the satellite that is scheduled to receive it next.
It is possible to eliminate interruptions in positioning due to successive reception stops for data acquisition from satellites on the first reception channel. In addition, in the case of a 5-channel receiver, 4 channels can simultaneously and continuously track 4 satellites, and in parallel, the other channel can perform preliminary acquisition of the next satellite, making it possible to instantly switch between satellites. It is possible to do so.

By the way, in GPS, all the errors associated with the measurement of the above-mentioned pseudo distances are converted into distances, and the user equivalent distance difference (U se
r Equivalent Ranoe E
rrrr.

(abbreviated as LIERE). This IJERE
The causes and the nominal values of the magnitudes of each cause in the P code are as shown in Table 1 of the Intrusion. (JE in C/A code
It is thought that in RE, both the ionospheric error and the receiver error are several times larger.

The GPS positioning error value (94th place accuracy) is this UERE,
It can be found by simply multiplying the degradation coefficient GDOP, and in the C/A code, the positioning accuracy is nominally 40 in radius for probability error (CEP).
m (50%).

Table 1: Types and magnitudes of equivalent ranging errors of user devices (P code) On the other hand, the geomagnetic positioning device 2 includes a vehicle speed sensor 2a and a geomagnetic sensor (magnetic compass), as shown in FIG.
2b and a signal processing means 2 that measures the current position of the vehicle from these outputs and outputs a position signal corresponding to the current position.
It has C.

The vehicle speed sensor 2a may be a known rotation speed sensor such as a reed switch type, a photoelectric type, or an electromagnetic type, and is installed, for example, at a speedometer cable outlet, inside the speedometer, etc. 2 per 1KJR
It is configured to output a pulse signal of 548 pulses or 12,740 pulses.

As shown in FIG. 7, the magnetic compass 2b has a detection coil 21, which includes a ring-shaped magnetic core 21a made of laminated permalloy thin plates, and a ring-shaped magnetic core 21a that extends over the entire circumference of the magnetic core 2ta. The excitation coil 21b is wound around the cross-sectional center line as the coil center line, the axial coil 21u is wound around the outside of the magnetic core 21a along one diameter of the circle drawn by the magnetic core 21a, and the magnetic core 21a is The V-axis coil 21v is wound around the outside of the magnetic core 21a along another diameter perpendicular to the above-diameter of the circle drawn.

Further, this magnetic compass 2b is provided with an excitation oscillator 22, and the frequency f given from this excitation f11 oscillator 22 is
The B-H characteristic of the detection coil 21 is saturated by the signal. When the B-H characteristic of the detection coil 21 is saturated, the U-axis coil 21u and the V-axis coil 21v are energized in response to external magnetism JiHo (horizontal component of earth's magnetism). i
An AC signal is generated by induction.

The magnetic compass 2b further includes frequency multiplying filter circuits 23u and 23v that filter these outputs, AC amplifiers 24U and 24v that amplify the filtered output voltage, and a circuit that doubles the frequency output from the excitation oscillator 22. A frequency multiplier 25 for multiplying
, 24v, and outputs a DC signal corresponding to the direction.
and a DC amplifier 28u that amplifies these DC signals,
It has 28v. The outputs U and 2 of the DC amplifiers 28u and 28v are output to the next stage signal processing means 2C.

When the above-mentioned detection coil 21 is rotated around the central axis of the detection coil 21 which is orthogonal to both the U and V axes, as shown in Fig. 8(A).
As shown in FIG.
Corresponding to the intersection angle α of u, the output voltage U from the U-axis output coil 21u is Ho Sinα, and the V-axis output coil 2
The output voltage V from 1v is )l.

It becomes COSα. Therefore, theoretically, each output voltage U,
The average value of (2) should be zero, but in reality, due to the influence of magnetization of heavy objects, external abnormal magnetic fields, etc., the average value of each output voltage uotvo does not become zero but is offset. Also,
Since the gains in the U-axis direction and the y-axis direction differ depending on the sensor sensitivity, the Lissajous curve drawn by both output voltages USV will draw an ellipse offset from the origin, as shown in FIG. 8(B).

Therefore, the signal processing means 2C includes a magnetic compass 2b.
An azimuth determining means that can measure the azimuth of the vehicle with true north as the +y direction as the direction of a vector from the origin to a point (XS'/'') on a circle centered on this from the output signal U1V of (not shown) is provided.

This direction determining means first calculates the average value uQ s v of the output voltage U in the U-axis and V-axis direction in order to eliminate the influence of magnetization on the vehicle body, external abnormal magnetic field, etc.

The highest value usax 1v+tax and the lowest value umi
n.

Determine from v win according to the following equations (1) and (2), and (
3) and (4), and includes an off-hit correction means (not shown) for obtaining an offset correction voltage U, (2) from which the offset of the ellipse is removed.

u a+ax -u 5in jJo= □ ・・・・・・(1)v g+a
x −v win Vo −□ ・・・・・・(2) U=u−too
・・・・・・(3)V-v-vo
(4) The Lissajous curve drawn by the off-pit correction voltage U output from this offset correction means, (2) draws an ellipse centered on the origin, as shown in FIG. 8(C). In addition, in order to eliminate the unevenness of the offset correction voltages U and ① caused by non-uniformity of sensor sensitivity, the above-mentioned azimuth determination means uses the formula (5) from the high and minimum R values of both offset correction voltages U and ②. Calculate the ellipticity K according to the formula, multiply this ellipticity K by the offset correction voltage V in the y-axis direction, and calculate the voltage V in the y-axis direction by (6)
It has sensor sensitivity ellipse correction means (not shown) for further correction according to the formula.

U□ ulaX −Ultn K=□=□ ・・・・・・(5) V□ VlaX −Vain V=K (v−V□ ) −・−・(6
) The Lissajous curve drawn by the output voltage U1v of this sensor sensitivity ellipse correction means is circular with the origin as the center, as shown in FIG. 8(D). The direction of the vehicle in the U1v locus-like system with the +U force direction magnetic north can be determined by the direction of the vector from the origin, which is the center of the Lissajous curve, to a point (U, 2) on the Lissajous curve.

However, the above-mentioned azimuth determination means has a U coordinate system in which the 10U direction is the magnetic north direction, and a true north direction corresponding to the azimuth on the map of the x, y coordinate system where the + In order to process it as the azimuth of A declination angle correction means is provided for converting the sieve into a sieve.

x −Vcos θ−Usin θ
...... (7) y = LJ cos θ+
V sin θ (8)
The direction of the vehicle on the map of the x, y coordinate system with the +X direction as the due north direction can be determined by the direction of the vector connecting the origin of the x, y coordinate system and the coordinates (x, y). become.

Assuming that the unit traveling distance ΔL is continuously traveled in the determined direction, what is the movement mΔX in the X-axis direction and the movement amount ΔY in the y-axis direction of the vehicle that traveled in that direction (9) ,
It can be determined using equation (10).

Δx=□×△L ・・・・・・(9)ΔY−□×
ΔL (10) Therefore, the coordinates are (X
Estimated current position (X.

Y) is X=Xo +ΔX...
... (11)Y=Yo+ΔY
・−−・−(12>. Also, if we assume that X2 +y2 = ΔL2, then
, Yo ), the estimated current position (X, Y) of a vehicle traveling while changing its direction from time to time is as follows.

Incidentally, errors occur between the actual travel distance and orientation and the estimated travel distance and estimated orientation based on the detected values due to various causes. It is extremely difficult to investigate the causes of this error one by one and eliminate the error for each cause. Therefore, the vehicle is actually driven over an arbitrary section, and the mileage correction coefficient R and the declination correction ωθ are determined according to the following program from the estimated straight-line distance and direction of that section and the actual straight-line distance and direction of the travel section. Function to calculate,
This gives the signal processing means 2C the function of calculating a pseudo current position corresponding to the actual traveling position.

That is, as shown in FIG. 9, the subroutine for setting the travel distance correction coefficient R and the declination angle correction ωθ is programmed as a back menu of the signal processing means 2C, and after starting the subroutine, the current position of the departure point (Xo ＋'
10) and destination (Xt, Vl) are set (Fl
). These points can be set by inputting a place name and storing the coordinate values corresponding to this place name in a memory (not shown).
Alternatively, by pressing a desired point on a map displayed on a display device (described later) from above the transparent matrix switch provided in front of the screen, the (Xo, Vo) point of the transparent matrix switch is set x 1°Vx.
) points in turn and their coordinates are stored in a memory (not shown).

Next, a message "Please drive to your destination" is displayed on the display device, for example, in a superimpose manner (F2). Thereafter, while the driver is driving toward the destination, the map and the estimated current position of the vehicle are displayed on the display device 11FD (F3). If the vehicle is actually at its destination (Xt
, ¥1), the estimated current position displayed on the display device is displayed as the destination (X2, V2), and it is confirmed whether the destination and destination match. (F4). If they match, the message ``arrived'' is displayed on the display device, for example, in a superimposed manner, indicating that the message has arrived. If they do not match, first the mileage correction coefficient R is calculated according to formulas (15) to (17) (F5), and then the declination correction amount θ is calculated as (18
) to (20) are performed (F6).

・・・・・・(15) ・・・・・・(16) R=□ ・・・・・・
(17)L.

V　　　　　　　V.

Vz　-y.

θ2= j a n −' (−) ・・・・・・
・(19〉x2 −X.

θ=θ2−θ1 ・・・・・・
(2o) Furthermore, the mileage correction coefficient R calculated last time
The deviation percentage ΔR of the current travel distance corrected image aH is calculated and displayed on the display device (F7), and it is determined whether the deviation percentage ΔR is within the allowable range (F8). If the deviation percentage 8R exceeds the allowable range, adjust the deviation percentage ΔR appropriately while looking at the display, and use the cursor movement keys (←, → key) to set the value of the selected digit. Operate the up key (key marked with ↑) or the countdown key (key marked with ↓) to set the number (F9), and replace the mileage correction coefficient R with the sum of 1 and l/100 of this number ΔR. (
F10). Then, the changed mileage correction coefficient R
Display the deviation percentage △R with respect to the mileage correction coefficient R before the change (F7), and if it is confirmed that it is within the allowable range (F8), the current deviation angle Δθ with respect to the previous declination correction ωθ will be displayed ( Fll), and it is determined whether or not it is within the allowable range (F12). If it exceeds the allowable range,
In the same way as changing the mileage correction coefficient aR, the deviation angle Δθ is set appropriately (F1a), and the changed deviation angle is re-displayed with ○ (Fll), and after confirming that this is within the allowable range, (F12), the back menu program of this subroutine is ended.

The mileage correction coefficient R and the declination correction aperture θ obtained in this way
is stored in the signal processing means 2C, and used for correcting the measured values by the vehicle speed sensor 2a and the magnetic compass 2b during subsequent positioning by the geomagnetic positioning device 2. That is, if we actually arrive at the destination (Xt, Vs) from the departure point (Xo, Vo), if the straight line distance between the departure point and the current position according to the measured value is , it will be output to the guidance means 5. The signal value is corrected to L/R=Lo, and if the direction of the current position from the starting point based on the measured value is θ2, the signal value output to the guidance means 5 is corrected to θ2-θ=01. Ru. Then, on the screen of the guidance means 5, the straight line distance L from the departure point in the direction of θ1 is displayed.
The current position of the vehicle is displayed at point o, that is, the above-mentioned destination.

The same applies to the destination and the transit points between the departure point and the destination.

The above-mentioned mileage correction coefficient 19 and declination angle correction amount θ may be initially set to appropriate values obtained from experience and ω. These corrections can be made by the driver starting the above-mentioned subroutine during any driving in response to, for example, changes in the magnetized state of the vehicle body due to variations in the earth's magnetic field, sudden external abnormality driving in I4i fields, etc. The i order is given to the signal processing means 2C of the geomagnetic positioning device 2, and the program is executed by proceeding, thereby ensuring positioning without positioning errors by the geomagnetic positioning device 2.

Also, for example, when the vehicle's key switch is turned off at the destination, the coordinates of the departure point (Xo, Vo) and the measured value coordinates of the destination (Xz, Vz) are memorized, and then the next time the vehicle departs from that destination. to its destination coordinates (Xs, VI
) as a new starting point, it is also possible to automatically start execution of the subroutine described above.

Furthermore, as shown in FIG. 10, for example, after pressing the current position on the map of the guidance means 5 at an arbitrary starting point and setting the current position as one absolute position (F14), the next It is possible to configure such a program that the starting point of positioning by the geomagnetic positioning device 2 is automatically corrected to the current position of the vehicle immediately before the end of positioning by the satellite-based positioning device @1. That is, after setting the initial absolute position (
F14) Calculate the estimated current position using the geomagnetic positioning device 2 from the starting point as you travel F15) Next, check whether the radio waves from the satellite have decreased below a predetermined strength, that is, the electric field strength It is determined whether GDOP (deterioration coefficient) is equal to or less than a predetermined value (F17).

Here, when it is determined that GDOP is less than the predetermined value, the previously set absolute position is corrected (replaced) with the position information of the current position obtained by the satellite-based positioning device 1.
F18). Thereafter, the process returns to step (F15) in which the geomagnetic positioning device 2 calculates the estimated current position based on the corrected absolute position.

Also, top! &! When the electric field strength is determined to be less than a predetermined value at the electric field strength determination step (F16), or when the radio waves from the secret are sufficiently strong, the GOOP is determined to be greater than the predetermined value at the GDOP determination step (Fll). When the current position is detected by the satellite-based positioning device 1, the position is not corrected based on the current position detected by the satellite-based positioning device 1, but the calculation step (F
Return to 15). In this way, when the starting point of positioning by the geomagnetic positioning device 2 is set to the current position of the vehicle immediately before the end of positioning by the satellite-based positioning device 1, from the starting point of positioning by the geomagnetic positioning device 2 to the current position. distance can be minimized, and positioning errors can be suppressed to a minimum. In addition, the above distance correction coefficient R and declination correction are automatically calculated from the coordinates of the estimated current position (relative position) by the geomagnetic positioning device 2 and the coordinates of the current position fil (absolute position) calculated by the satellite positioning device 1. It may be configured to calculate the amount θ.

As detailed above, according to this embodiment, when the deterioration coefficient is less than a predetermined value and the electric field strength exceeds a predetermined value, that is, when the error in positioning by signals from the satellite is small,
The current position W1 is identified with high accuracy based on the positioning data of the satellite-based positioning device.

On the other hand, when the deterioration coefficient is more than a predetermined value or the electric field strength is less than a predetermined value, that is, when the positioning error due to the signal from the satellite is large and the satellite-based positioning device 1 cannot obtain the required positioning accuracy, the switching device 24 Switching to positioning by the positioning device 2 used, this allows the current position 1fl to be constantly determined based on the positioning data of the positioning method with higher positioning accuracy.
This means that you can do the following.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is an overall configuration diagram showing an example of the present invention, FIG. 3 is a perspective view showing an outline of GPS, and FIG. 4 is an explanation of the principle of GPS positioning. Figure 5 is a block diagram of the satellite transmitting circuit, Figure 6 is a block diagram of the satellite-based positioning device, Figure 7 is a block diagram of the magnetic compass, and Figure 8 (A) is a block diagram of the satellite-based positioning device. Output signal diagrams of the magnetic compass; Figures 8 (B) to (E) are Lissajous curve diagrams sequentially showing the procedure for correcting the magnetic compass output by the signal processing means of the geomagnetic positioning device; Figure 9 is the geomagnetic positioning device FIG. 10 is a flowchart showing the procedure for automatically setting the positioning start point of the geomagnetic positioning device. a(1)...°Satellite-based positioning means b(2)...Other positioning means c (1, 2, 4)...Current position recognition means d(3).
... Reception state detection means e (4) ... Prohibited means Figure 1 Drawing extension t1 Exertion Figure 9 Figure 10 Procedure corrector (method) March 13, 1985 Mr. Akio Kuroda, Commissioner of the Patent Office, PA. 1.1!Display of 1986 Patent Application No. 296.217 2, Navigation device 3 with the title of the invention wJIiii, Relationship with the person making the amendment case Patent application Colonel Address: 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture 1 name (
313) Mazda Motor Corporation Representative Ken Yamamoto-4, Agent address 5-5, 7th floor, Hauraiya Pill, 5-2-1 Roppongi, mm-ku, Tokyo, Date of amendment order 6, Subject of amendment 1) Drawing 7, Contents of amendment 1> Replace Figures 2 to 10 with clearer ones. 8. Attached documents

Claims (1)

[Scope of Claims] A satellite-based positioning means for measuring the current position of the vehicle by receiving radio waves from a satellite, and another positioning means for measuring the current position of the vehicle, and at least one of the positioning means for measuring the current position of the vehicle. current position recognition means for recognizing the current position of the vehicle based on positioning data; reception state detection means for detecting a deterioration coefficient and electric field strength based on radio waves from the satellite; and the deterioration detected by the reception state detection means. A navigation device for a vehicle, comprising: prohibition means for prohibiting recognition of the current position of the vehicle based on positioning data of the satellite-based positioning means when the coefficient is greater than or equal to a predetermined value or the electric field strength is less than or equal to a predetermined value. .