JPH0781869B2 - Vehicle guidance device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle running guidance device capable of grasping the current position of a vehicle with high accuracy and performing more accurate vehicle running guidance.

[Conventional technology]

Conventionally, for example, as disclosed in Japanese Utility Model Publication No. 58-2620, the vehicle's current distance and target position are detected on the map displayed on the monitor screen by detecting the traveling distance and direction of the vehicle from a certain reference point. BACKGROUND ART There is known a vehicle travel guidance device that displays and displays a route through which the vehicle can reach a target position. However, in such a conventional vehicle travel guidance device, the current position of the vehicle is grasped as, so to speak, a relative position with respect to a reference point. Occurs.

Therefore, it is conceivable to measure the current position of the vehicle as, so to speak, an absolute position using radio waves emitted from a satellite. For example, it is conceivable to measure the current position of the vehicle as an absolute position by using a global positioning satellite system (hereinafter, referred to as GPS) currently under development. This GPS finds the distance from each satellite by the radio waves emitted from four artificial satellites (called NAVSTAR), and finds the intersection point of a spherical surface centered on the position of each satellite with these distances as the radius. As a result, the current position of the vehicle is measured.

Note that the distance data obtained from the radio waves received from each satellite includes an error such as ionospheric delay. The error included in these distance data, so-called distance measurement error, affects the positioning error of the current position of the vehicle, but the degree of the effect changes depending on the geometrical positional relationship between each satellite and the vehicle. For example, when satellites orbiting the earth are widely dispersed, the influence of each ranging error on the positioning error is small, and sufficient positioning accuracy can be obtained, while the satellites approach each other. If so, the positioning accuracy decreases.

The degree of influence of the ranging error due to such a geometrical positional relationship on the positioning error is, for example, “NAVIGATION”; Journal of
The Institute of Navigation., Vol.25 (1978), No.2, S
ummer, pp.102-125 and `` GLOBAL POSITIONING SYSTE
M ''; THE INSTITUTE OF NAVIGATON., Vol.1 (1980), pp10
As described in the literature such as −11, the degradation coefficient (Geom
It is calculated as etrical Dilution Of Precision (GDOP). The larger the GDOP value, the larger the positioning error. [Problems to be solved by the invention] However, in the method of positioning by using the received radio waves from the satellites as described above, the position of each satellite and the reception on the ground are Obstacles may deteriorate the reception status or make it impossible to receive. For example, when a vehicle travels in a tunnel, reception of radio waves from an artificial satellite may not be possible. Further, as described above, there are cases where the current position of the vehicle cannot be accurately grasped due to the geometrical positional relationship between each satellite and the vehicle.

The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a vehicle travel guidance device that can always grasp the current position of a vehicle with high accuracy and can perform more accurate vehicle travel guidance. Especially.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the vehicle travel guidance device according to the present invention obtains distance data corresponding to the distance from each satellite by the received radio waves from a plurality of satellites, and based on these distance data, the vehicle A first positioning unit that measures the current position and outputs a current position signal corresponding to this current position, and a current position is obtained by detecting the traveling distance and azimuth of the vehicle from the reference position, and corresponds to this current position. Positioning based on an error of each of the above distance data from the second positioning means that outputs the current position signal, the electric field intensity of the radio wave received by the first positioning means, and the geometrical positional relationship between each satellite and the vehicle. With respect to the deterioration coefficient obtained as a value indicating the degree of increase in error, it is possible to determine whether or not each of the deterioration coefficients exceeds a predetermined value, and the above determination means determines that the electric field strength exceeds the predetermined value and the deterioration coefficient Above when it is determined that the value less than the first
When the output of the positioning means is selected and it is determined that the electric field strength exceeds a predetermined value and the deterioration coefficient exceeds a predetermined value, and when the electric field strength is determined to be less than the predetermined value, the second
And switching means for selecting the output of the positioning means.

[Work]

According to the above configuration, when the electric field strength of the radio wave received from the satellite exceeds a predetermined value and the deterioration coefficient is equal to or less than the predetermined value, the current position of the vehicle can be accurately determined by the positioning by the first positioning means. To be grasped. On the other hand, even if the electric field strength of the radio wave received from the satellite exceeds a predetermined value and the positioning can be performed by the first positioning means, the deterioration coefficient is large and the positioning error in the first positioning means exceeds the allowable range. In such a case, it is possible to switch to grasp the current position of the vehicle by the output of the second positioning means instead of the first positioning means, so that the current position of the vehicle can be positioned with required accuracy. it can.

In this way, by discriminating the deterioration coefficient in addition to the electric field strength of the received radio wave and performing switching to select one of the outputs of the first and second positioning means, the current position of the vehicle can be more accurately determined. It can be grasped and, for example, it is possible to guide the traveling of the vehicle more accurately than in the case where either one of the outputs of the first and second positioning means is selected only by the electric field strength of the radio wave received from the satellite. it can.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9.

FIG. 1 is a block diagram showing an outline of an embodiment of the present invention. The vehicle travel guidance device shown in this FIG. 1 is a satellite-based positioning device 1 as a first positioning means and a second positioning means. And a positioning device 2 using geomagnetism.

As shown schematically in FIG. 2, for example, the satellite-based positioning device 1 includes 18 to 21 units of terrestrial main control stations 1a which are controlled via, for example, four terrestrial antennas 1b appropriately distributed. Of the satellites, four satellites S1 to S4 within the receivable area (field of view)
It consists of the user part of the GPS that determines the current position of the vehicle based on the radio waves transmitted from.

This satellite-based positioning device 1 uses the satellite position, satellite perturbation,
It is known that the positioning accuracy may be deteriorated due to the state of the ionosphere, or that positioning may become impossible locally for a very short time. It is also known that obstacles on the ground, such as traveling in a tunnel, make it difficult or impossible to receive necessary radio waves.

Further, as described above, the positioning accuracy is a deterioration coefficient (Geometri) that represents the degree of increase in positioning error determined by the geometrical positional relationship between the satellite used for positioning and the positioning point (vehicle).
cal Dilution Of Precision. Also called GDOP for short). That is, when the strength of the signal from the required satellite falls below the predetermined value or when GDOP greatly exceeds the predetermined value, the positioning error exceeds the allowable amount.

Therefore, the traveling guidance device for a vehicle detects the strength of the received signal (electric field strength), and based on the position of each satellite used for positioning and the current position of the vehicle calculated at this time. A GDOP judging means 3 is provided as a judging means for calculating the GDOP and comparing it with a predetermined value.

When the strength of the received signal is less than the specified value, GD
When the GDOP determining means 3 determines that the OP exceeds the predetermined value, a switching means 4 is provided for switching the position signal to be used from that of the satellite-based positioning device 1 to that of the geomagnetic positioning device 2. That is, when the strength of the received signal from the satellite-based positioning device 1 exceeds a predetermined value and the positioning error is within a predetermined range, the position signal of the satellite-based positioning device 1 is selected, and otherwise, The position signal of the geomagnetic utilizing positioning device 2 is selected, and the position signal is output from the switching unit 4 to the guiding unit 5 that guides the traveling of the vehicle.

This guiding means 5 has, for example, a video screen whose surface is covered with a transparent matrix switch, displays the destination and the current position of the vehicle on a map displayed on the screen, and also informs the driver of the current position. It is configured to guide the traveling of the vehicle by teaching the route to the ground, the direction, the traveling distance, and the like. Of course, it is also possible to use another known structure for the guiding means 5.

The principle of positioning by GPS is as follows.

That is, if there is a clock that is completely synchronized with the transmission point and the reception point of the radio wave, and the transmission signal is controlled by that clock,
By measuring the reception timing at the receiving point, the propagation time of the radio wave between the transmitting and receiving points can be obtained, and by multiplying it by the speed of light, the distance between the transmitting and receiving points can be obtained.

Now, as shown in FIG. 3, there are three satellites S1, S2, S3 in the user's field of view (receivable area).
It is assumed that the S2 and S3 are transmitting the distance measurement signals by the clocks synchronized with each other. By measuring the reception time of these signals at the reception point P, the distance between each satellite S1, S2, S3 and the reception point P can be obtained, and the reception point P intersects three spherical surfaces centering on each satellite S1, S2, S3. Can be asked as However, synchronizing the clock of the receiving point P with that of the transmitting point is technically problematic and disadvantageous in reducing the cost of the receiver. This problem is solved by increasing the number of satellites receiving the signal by one more.

FIG. 3 is shown two-dimensionally for easy understanding. If the clock of the receiving point is delayed by Δtu from the clock of each satellite, the radius of the three circles measured will be Δtuc (c is the speed of light) larger than the actual one, and they will intersect at one point originally. The three power circles will not intersect (solid line diagram). Δtuc so that these three circles intersect at one point
If the value of is adjusted, then Δtu can be obtained at the same time as the position of the reception point P.

In GPS, a measured value of a distance that differs by Δtuc from the true distance Ri (*) with respect to the satellite i is called a pseudo distance. The pseudorange Ri for satellite i is Ri = Ri (*) + cΔ
It is represented by t _ai + c (Δtu−Δt _svi ).

Here, Δt _ai is the delay time of radio waves in the ionosphere and the troposphere, and Δt _svi is the time offset of the clock of satellite i. Instead of synchronizing the atomic clocks on the satellite with each other, the offset value is measured, the value is predicted, and the value of Δt _svi is calculated and transmitted from the satellite.

In order to perform three-dimensional positioning, it is possible to solve a total of four unknowns of three position coordinates and Δtu using four pseudorange measurement values for four satellites with i = 1 to 4. Similarly, if the Doppler frequency of the signal from the satellite, that is, the measured value of the pseudorange change rate is used, the three-dimensional velocity of the user can be measured. If the user's position is calculated based on the satellite's position, the user must know the position of the satellite and the state of the clock on the satellite, which changes from moment to moment. Broadcast from satellite.

Each satellite is equipped with a receiver circuit (not shown) for receiving radio waves transmitted from the main control station 1a via the ground antenna 1b, and a transmitter circuit 10 shown in FIG. This transmitter circuit 10
Is, for example, a reference frequency oscillation circuit 11 that outputs a reference frequency signal of 12.23 MHz, and the frequency of the reference frequency signal that is output from this is multiplied by 154 times to form a _first carrier L ₁ carrier (1575.42 MHz). L ₁ multiplier 12 and the frequency of the reference frequency signal multiplied by 120 to generate the second carrier L ₂
And an L ₂ multiplier 13 forming a carrier wave (1227.6 MHz).

The transmitting circuit 10 includes a clock forming circuit 14 that forms a clock signal of a predetermined cycle from a reference frequency signal, and two types of codes called a P code and a C / A code as a ranging signal from the reference frequency signal and the clock signal. It has a code generation circuit 15 which forms a signal, and a computer 16 which outputs data relating to the position of a satellite and the state of a clock on the satellite which are time-controlled by the clock signal.

The P-code is a high-precision secret code that can be used only by users who are especially authorized by the military. It is a form of quadrature-modulating both L ₁ and L ₂ carriers after superimposing it on the data output from the computer 16. Sent at a repetition rate of 10.23Mbi
t / s, a long code that lasts for a week. The C / A code is a code that is used for rough positioning (standard positioning) and for capturing the P code, and is open to the public. This C / A code signal, after being superimposed on the data output from the computer 16, is transmitted in the form of modulating both L ₁ and L ₂ carrier waves, the repetition rate is 1.023 Mbit / s, and the length is 1023 bits. , That is, 1ms
Repeated every time. The C / A code generating circuit is composed of, for example, a Gold code generating circuit using two 10-stage shift registers.

The data output by the computer 16 is measured and predicted by a control unit on the ground, stored in a storage circuit (not shown) of the satellite, and sequentially read. These data are transmitted at a predetermined timing with a transmission rate of 50 bits / s, for example. In this data, telemeter words, handover words, ionosphere correction parameters, 1-frequency receiver delay correction, clock correction data age, clock correction reference time,
GPS system time, orbit prediction age, orbit element reference time, average near point angle at orbit element reference time, eccentricity, long radius square root, ascending node red radius, orbit inclination angle, perigee argument,
It contains data such as perturbations at ascending and descending points, correction of average motion, parameters for tilt angle correction, orbit correction items, satellite identification numbers, data subframe reference times, and satellite health conditions.

In addition, to predict the period during which the user's receiver can receive the signals of each satellite, select the combination of satellites that gives the best positioning accuracy from the satellites in the field of view, and acquire the signals from the satellites as soon as possible. The almanac data of other satellites belonging to the system are also included so that the receiver circuitry can be preconfigured and so on.

The control part is the main control station 1a and the ground antennas 1b arranged at a plurality of fixed points (four or more are planned) on the ground.
And a monitor station 1c arranged at a plurality of fixed points (four or more are planned) on the ground. The main control station 1a tracks the satellite via the terrestrial antenna 1b, predicts the clock on the satellite and the orbit of the satellite according to the result, and stores the data for putting them in the memory of the satellite so that they are broadcast from the satellite. It is a manned facility equipped with a large-scale computer and a series of operation control consoles, which are provided to receive the telemeters and commands required for satellite control as well as to transmit. The monitor station 1c is an unmanned station equipped with a satellite signal receiver, an atomic clock, and a meteorological instrument for calculating the tropospheric delay.

As shown in FIG. 1, the satellite-based positioning device 1 which is the user portion determines the current position of the vehicle from the receiver 6 which receives the signal of the required satellite and the received signal, and the position corresponding to the current position. And a signal processing means 7 for outputting a signal. Further, as shown in FIG. 5, the satellite-based positioning device 1 is provided with a crystal oscillator 8 which outputs a reference frequency signal which is an overall timing control signal, and an operation timing of the signal processing means 7 from the reference frequency signal. It has a clock oscillation circuit 9 for forming a clock signal to be controlled, and has an antenna 17, a preamplifier 18, and a bandpass filter 19 connected to the front stage of the receiver 6.

The receiver 6 includes a frequency synthesizing circuit 61 for producing a signal having the same pattern as the data on the carrier of the transmitter 10 of the satellite, the position of the satellite and the state of the clock on the satellite based on the reference frequency signal oscillated by the crystal oscillator 8. The code generation circuit 62 which receives the clock signal output from the clock oscillation circuit 9 and forms a code signal having the same pattern as the distance measurement signal and the output signals of the frequency synthesis circuit 61 and the code signal generation circuit 62 Data and carrier wave detector 63 for correlation detection of data relating to the clock and satellite orbit and carrier wave, and a code lock detector 64 for performing correlation detection of the distance measurement signal by the code signal output from the code generation circuit 62. There is. The timing of the signal processing means 7 is controlled by the clock signal output from the clock oscillation circuit 9.

Although FIG. 5 shows a receiver 6 having one reception channel, two reception channels are provided, and the first reception channel is for sequentially switching and receiving signals from four satellites within the field of view. The second reception channel is used to acquire broadcast data from each satellite and to preliminarily capture signals from the satellite to be received next.
It is possible to eliminate the interruption of positioning due to the sequential stoppage of reception for data acquisition from the satellite of the reception channel.
In the case of a 5-channel receiver, 4 satellites are simultaneously and continuously tracked on 4 channels, and in parallel with this, the next satellite is pre-acquired on another channel, and the satellite used is switched instantaneously. It is possible to

By the way, in the GPS, as described above, four pseudo distances are measured as distance data for each satellite, and the vehicle is positioned based on these distance data. At this time, all the errors involved in the measurement of the pseudo distance are converted into a distance, which is called a user equivalent distance difference (abbreviated as UERE). The nominal values of the cause of the UERE and the cause of each P code are shown in Table 1 below. UERE in C / A code is believed to have several times the error in the ionosphere and the error in the receiver.

And the positioning error value (positioning accuracy) of GPS is the above UERE.
It can be obtained by multiplying the deterioration coefficient GDOP described above, and the positioning accuracy of the C / A code is nominally 40 m in radius for probability error (CEP).
(50%).

On the other hand, as shown in FIG. 1, the geomagnetic utilizing positioning device 2 determines the current position of the vehicle from the vehicle speed sensor 2a, the magnetic compass 2b and their outputs, and outputs a position signal corresponding to the current position. And signal processing means 2c.

The vehicle speed sensor 2a may be a reed switch type, a photoelectric type, a known rotational speed sensor such as an electromagnetic type, for example, a speedometer cable outlet, is provided in the speedometer, etc., corresponding to the traveling distance, for example, It is configured to output a pulse signal of 2548 pulses or 12740 pulses per km.

As shown in FIG. 6, the magnetic compass 2b has a detection coil 21. The detection coil 21 has a ring-shaped magnetic core 21a formed by laminating permalloy thin plates and a center of a cross section of the magnetic core 21a over the entire circumference thereof. Excitation coil 21b wound around a wire as a coil center line and magnetic core 21b along a diameter of a circle drawn by magnetic core 21a.
The u-axis coil 21u is wound on the outside of a, and the v-axis coil 21v is wound on the outside of the magnetic core 21a along another diameter orthogonal to the one diameter of the circle drawn by the magnetic core 21a.

An excitation oscillator 22 is provided in the magnetic compass 2b, and the BH characteristic of the detection coil 21 is saturated by the signal of the frequency f given from the excitation oscillator 22. In the state where the BH characteristic of the detection coil 21 is saturated, the u-axis coil 21 corresponds to the external magnetic field H ₀ (horizontal component of geomagnetism).
An AC signal is generated in the u and v axis coils 21v by electromagnetic induction.

The magnetic compass 2b further includes frequency dividing filter circuits 23u and 23v for filtering these outputs, AC amplifiers 24u and 24v for amplifying the filtered output voltage, and a frequency output from the excitation oscillator 22 is doubled. Frequency multiplier 25 and phase shifter
26, each phase detector 27u, which inputs the phase signal of frequency 2f via this phase shifter 26, outputs the DC signal corresponding to the azimuth by phase-detecting the output of the AC amplifiers 24u, 24v,
27v and DC amplifiers 28u, 28v that amplify these DC signals
Have and. The outputs u and v of the amplifiers 28u and 28v are output to the signal processing means 2c at the next stage.

The detection coil 21 is a detection coil 21 which is orthogonal to both u and v axes.
When it is rotated about the central axis of, the output voltage u from the u-axis output coil 21u corresponds to the direction of geomagnetism and the intersection angle α of the u-axis output coil 21u, as shown in FIG. 7 (A). H
₀ sin α, and the output voltage v from the v-axis output coil 21v becomes H ₀ cos α.

Therefore, theoretically, the average value of each output voltage u, v should be zero, but in reality, the average value u of each output voltage is affected by the magnetization of the vehicle body, the external abnormal magnetic field, etc. ₀ and v ₀ do not become zero but are offset, and the gains in the u-axis direction and the v-axis direction differ depending on the sensor sensitivity.
The Lissajous curve drawn by u and v draws an ellipse offset from the origin, as shown in FIG. 7 (B).

Therefore, in the signal processing means 2c, from the output signals u and v of the magnetic compass 2b, the direction of the vehicle whose true north is the + y direction is set as follows from the origin, and one point on a circle centered on the direction ( x,
An azimuth discriminating means (not shown) is provided which can be measured as the direction of the vector toward y).

The azimuth determining means first determines the average values u ₀ , v ₀ of the output voltages u, v in the u-axis and v-axis directions in order to remove the influence of magnetization on the vehicle body, external abnormal magnetic field, etc. The offsets represented by the equations (3) and (4) obtained by _obtaining the maximum values u _max , x _max and the minimum values u _min , v _{min according} to the following equations (1) and (2), and removing the offset of the ellipse. It has an offset correction means (not shown) for obtaining the correction voltages U and V.

U = u−u ₀ (3) V = v−v ₀ (4) The Lissajous curve drawn by the offset correction voltages U and V output from this offset correction means is shown in FIG. 7 (C). Draw an ellipse centered on the origin as shown.

The azimuth discriminating means uses the formula (5) from the maximum and minimum values of the offset correction voltages U and V in order to eliminate the unevenness of the offset correction voltages U and V caused by the nonuniformity of the sensitivity of the sensor. The ellipticity K is calculated according to
And a sensor sensitivity ellipse correction means (not shown) for multiplying the offset correction voltage V in the V-axis direction to further correct the voltage V in the V-axis direction according to the equation (6).

V = K (v−v ₀ ) ... (6) The Lissajous curve drawn by the output voltages U and V of this sensor sensitivity ellipse correction means becomes a circle centered on the origin as shown in FIG. 7 (D). . The direction of the vector in the U, V coordinate system with the magnetic north in the + U direction can be determined by the direction of the vector from the origin, which is the center of the Lissajous curve, to one point (U, V) on the Lissajous curve.

However, the direction discriminating means uses the magnetic north in the + U direction.
In order to process the azimuth of the vehicle in the U and V coordinate systems as the true azimuth corresponding to that azimuth on the map of the x and y coordinate system where the + x direction is the true north direction, the deviation obtained as described below is used. Using the angle correction amount θ, set the coordinates of the above point (U, V) to (7)
A declination correction means for converting to (x, y) coordinates is provided according to the equation (8).

x = Vcosθ + Usinθ (7) y = Ucosθ + Vsinθ (8) The x, y coordinate system in which the + x direction is the true north direction depending on the direction of the vector connecting the origin of this x, y coordinate system and the coordinates (x, y). The true direction of the vehicle on the map will be determined.

Assuming that the vehicle has traveled the unit travel distance ΔL continuously in the direction determined here, the movement amount ΔX in the x-axis direction and the movement amount ΔY in the y-axis direction of the vehicle traveling in that direction are (9)
It can be calculated by equation (10).

Therefore, the unit travel distance Δ from the departure point whose coordinates are (X ₀ , Y ₀ ).
The estimated current position (X, Y) when traveling L is: X = X ₀ + ΔX (11) Y = Y ₀ + ΔY (12) If x ² + y ² = ΔL ² is assumed here, the estimated current position (X, Y) of the vehicle traveling while changing the direction from the starting point (X ₀ , Y ₀ ) momentarily is Becomes

By the way, an error occurs between the actual traveling distance and azimuth and the estimated traveling distance and estimated azimuth based on the detected value due to various causes. It is extremely difficult to investigate the cause of this error one by one and eliminate the error for each cause.

Therefore, the vehicle is actually driven over an arbitrary section, and from the estimated linear distance and estimated azimuth of the section and the linear distance and azimuth of the actual traveling section, the traveling distance correction coefficient R and the declination correction amount are calculated according to the following program. The signal processing means 2c is provided with a function of calculating θ and a function of calculating a pseudo current position corresponding to an actual traveling position.

That is, as shown in FIG. 8, these travel distance correction coefficients R
And a declination correction amount θ are programmed as a back menu of the signal processing means 2c. After the subroutine is started, first, the current position (x ₀ , y ₀ ) of the departure point and the destination (x ₁ , y ₁ ) Is set (F1).

These points are set by inputting a place name and storing coordinate values corresponding to the place name in a memory (not shown), or by providing a desired point of a map displayed on a display device D described later on the front surface of the screen. By pressing from above the transparent matrix switch, the (x ₀ , y ₀ ) point and the (x ₁ , y ₁ ) point of the transparent matrix switch are turned on in order and their coordinates are stored in a memory not shown, etc. It can be executed by the method.

Then, the message "Please drive to the destination" is displayed on the display device D, for example, by the superimpose method (F2). Then, while the driver travels toward the destination, the map and the estimated current position of the vehicle are displayed on the display device D (F3).

When the vehicle actually arrives at the destination (x ₁ , y ₁ ), the estimated current position displayed on the display device D is the destination (x ₂ , y 1).
_It is displayed as ₂ ), and it is confirmed whether the destination and the destination match (F4). If they coincide with each other, a message of “arrival” is displayed on the display device D by the superimpose method, for example, as indicating that it has arrived. If they do not match, the mileage correction coefficient R is first calculated according to the equations (15) to (17) (F5), and then the declination correction amount θ is (18).
~ Calculated according to equation (20) (F6).

_{L = {(x 2 -x 0} ) 2 + (y 2 -y 0) 2} 1/2 ...... (15) L 0 = {(x 1 -x 0) 2 + (y 1 -y 0) 2 } ^1/2 …… (16) θ = θ ₂ −θ ₁ (20) Further, the deviation percentage ΔR of the current mileage correction coefficient R with respect to the previously calculated mileage correction coefficient R is calculated and displayed on the display device D (F7), It is determined whether the deviation percentage ΔR is within the allowable range (F8).

When the deviation percentage ΔR exceeds the permissible range, the deviation percentage ΔR is appropriately operated while observing the display device D, and the cursor movement key (←, → mark keys) is operated to count up the numerical value of the selected digit. Operate the (↑ mark key) or the countdown key (↓ mark key) to enter the number (F9), and replace the travel distance correction coefficient R with 1 plus 1/100 of this number ΔR. (F10).

Then, the deviation percentage ΔR of the changed mileage correction coefficient R with respect to the mileage correction coefficient R before the change is displayed (F7), and when it is confirmed that it is within the allowable range (F7)
8), current deviation angle Δθ with respect to the previous deviation angle correction amount θ
Is displayed (F11), and it is determined whether it is within the allowable range (F11
12). If it exceeds the allowable range, the deviation angle Δθ is appropriately registered as in the case of changing the mileage correction coefficient R (F1
3) Then, the changed deviation angle Δθ is displayed again (F11), and after confirming that it is within the allowable range (F12), the back menu program of this subroutine is ended.

The travel distance correction coefficient R and the declination correction amount θ thus obtained
Is stored in the signal processing means 2c and is used for correction of the measured values by the vehicle speed sensor 2a and the magnetic compass 2b in the subsequent positioning by the geomagnetic positioning device 2.

That is, now from the starting point (x ₀ , y ₀ ) to the destination (x ₁ ,
y ₁ ) is reached, when the linear distance between the starting point and the current position according to the measured value is L, the signal point output to the guide means 5 is corrected to L / R = L ₀ , and the measured value is changed. If the azimuth of the current position from the departure point based on the above is θ ₂ , the guiding means 5
The signal point output to is corrected to θ ₂ −θ = θ ₁ . Then, the current position of the vehicle is displayed on the screen of the guide means 5 at the point of L ₀ in a straight line distance from the departure place in the direction of θ ₁ , that is, the above-mentioned destination.

The same applies to the transit point between the departure point and the destination as in the case of the destination.

The travel distance correction coefficient R and the deviation angle correction amount θ may be initially set to appropriate numbers and amounts obtained empirically. Then, these corrections are, for example, a command for the driver to start the above-mentioned subroutine in arbitrary traveling in response to changes in the magnetized state of the vehicle body due to fluctuations in the earth's magnetism, sudden external abnormal magnetic field traveling, etc. Is given to the signal processing means 2c of the geomagnetic utilizing positioning device 2 and executed by advancing the program thereof, whereby the geomagnetic utilizing positioning device 2 can secure the positioning without a positioning error.

Also, for example, when the key switch of the vehicle is turned off at the destination, the coordinates of the departure point (x ₀ , y ₀ ) and the measured value coordinates of the destination (x ₂ , y ₂ ) are stored in memory and then the It is also possible to automatically start the execution of the above-mentioned subroutine by entering the destination coordinates (x ₁ , y ₁ ) as a new departure point when leaving the place.

Further, as shown in FIG. 9, for example, after pressing the current position on the map of the guiding means 5 at an arbitrary departure place to set the current position as one absolute position (F14), According to the program, the starting point of positioning by the geomagnetic positioning device 2 is automatically corrected to the current position of the vehicle immediately before the positioning by the satellite positioning device 1 ends.

That is, after the initial absolute position is set (F14), the estimated current position is calculated from the place of departure from the place of departure by the geomagnetic field positioning device 2 (F15), and then radio waves of a predetermined intensity or more are received from the satellite. Whether or not (F1
6) When radio waves of a predetermined intensity or more are received from the satellite, it is further determined whether GDOP is a predetermined value or less (F17).

When it is determined that GDOP is equal to or less than the predetermined value, the absolute position previously set is corrected (replaced) by the position information of the current position obtained by the satellite-based positioning device 1 (F1
8). After that, the step of calculating the estimated current position from the corrected absolute position by the geomagnetic positioning device 2 (F1
Return to 5).

In addition, when the received signal strength is determined to be less than or equal to a predetermined value in the received signal strength determination step (F16), or when the signal from the satellite is strong enough, the GDO is determined in the GDOP determination step (F17).
When it is determined that P exceeds the predetermined value, the estimated current position of the estimated position by the geomagnetic utilization positioning device 2 from the last set absolute position is not corrected by the current position detected by the satellite utilization positioning device 1. Return to the calculation stage (F15).

In this way, when the starting point of the positioning by the geomagnetic using positioning device 2 is set to the current position of the vehicle immediately before the end of the positioning by the satellite using positioning device 1, from the starting point of the positioning by the geomagnetic using positioning device 2 to the current position. The distance can be minimized and the positioning error can be minimized. Further, from the coordinates of the estimated current position (relative position) by the geomagnetic positioning device 2 and the coordinates of the current position (absolute position) obtained by the satellite positioning device 1, the travel distance correction coefficient R and the declination correction amount θ are automatically obtained. It may be configured to calculate and.

As described above, according to the vehicle travel guiding apparatus of the present embodiment, the switching means 4 determines that the strength of the received signal exceeds the predetermined value and the deterioration coefficient is less than the predetermined value by the GDOP determining means 3. When the output of the satellite-based positioning device 1 is selected and the current position of the vehicle is grasped, the strength of the received signal exceeds the predetermined value and the deterioration coefficient exceeds the predetermined value by the GDOP judging means 3. When it is determined and when the strength of the received signal is determined to be less than or equal to a predetermined value, the output of the geomagnetic utilizing positioning device 2 is selected to grasp the current position of the vehicle.

As described above, when the strength of the received signal exceeds the predetermined value and the deterioration coefficient is equal to or less than the predetermined value, the satellite-based positioning device 1 can grasp the current position of the vehicle with high accuracy. . On the other hand, when the positioning error by the satellite-based positioning device 1 exceeds the allowable range, the current position signal of the vehicle positioned by the value-magnetic-based positioning device 2 is selected instead of the satellite-based positioning device 1, so that the vehicle positioning is performed. The accuracy can be within the allowable range. That is, since one of the outputs of the satellite-based positioning device 1 and the magneto-optical positioning device 2 is selected according to the deterioration coefficient in addition to the strength of the received signal, it is possible to grasp the current position of the vehicle with high accuracy. You can

Therefore, compared with the case where the current position of the vehicle is measured by selecting one of the outputs of the satellite-based positioning device 1 and the magnetic-value-based positioning device 2 based only on the strength of the received signal, the current position of the vehicle can be measured with higher accuracy. The position can be grasped, and thereby the vehicle can be guided more accurately.

〔The invention's effect〕

As described above, if the electric field strength of the signal from the satellite exceeds the predetermined value and the deterioration coefficient is equal to or less than the predetermined value, the vehicle travel guidance device of the present invention grasps the current position with high accuracy by the first positioning means. it can. Further, if the electric field strength of the signal from the satellite is below a predetermined value, or if the electric field strength of the signal from the satellite exceeds a predetermined value and the deterioration coefficient exceeds a predetermined value, that is, the positioning accuracy required for positioning by the first positioning means. When the position cannot be obtained, the switching unit can grasp the current position by the second positioning unit instead of the first positioning unit, and can secure the required positioning accuracy. Therefore, there is an effect that the current position of the vehicle can always be grasped with high accuracy, and thereby the vehicle can be guided more accurately.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an embodiment of the present invention,
FIG. 2 is a perspective view showing the outline of GPS, FIG. 3 is an explanatory view of the principle of GPS positioning, and FIG. 4 is a block diagram of a satellite transmission circuit.
FIG. 5 is a block diagram of a satellite-based positioning device, FIG. 6 is a block diagram of a magnetic compass, FIG. 7 (A) is an output signal diagram of a magnetic compass horizontally rotating with respect to the earth's magnetism, and FIG. 7 (B).
(E) is a Lissajous curve diagram sequentially showing the procedure of correcting the magnetic compass output by the signal processing means of the geomagnetic utilizing positioning device, and FIG. 8 is a subroutine for setting the traveling distance correction coefficient and the declination correction amount in the geomagnetic utilizing positioning device. Flow diagram,
FIG. 9 is a flowchart showing a procedure for automatically setting the positioning start point of the geomagnetic utilizing positioning device. Reference numeral 1 is a first positioning means (satellite positioning apparatus), 2 is a second positioning means (geomagnetic positioning apparatus), 3 is a GDOP judging means (determining means), 4 is a switching means, 5 is a guiding means, and S1 to S4 is a satellite.

Claims (1)

[Claims] 1. A distance data corresponding to a distance from each satellite is obtained from radio waves received from a plurality of satellites, a current position of a vehicle is measured based on the distance data, and a current position signal corresponding to the current position is obtained. A first positioning means for outputting the current position, a second positioning means for detecting the current distance by detecting the traveling distance and azimuth of the vehicle from the reference position, and outputting a current position signal corresponding to the current position; The deterioration coefficient obtained as a value indicating the degree of increase in the positioning error based on the error in each of the above distance data from the electric field strength of the radio wave received by the positioning device of No. 1 and the geometrical positional relationship between each satellite and the vehicle. With respect to each of the above, the determination means for determining whether or not each exceeds a predetermined value, and the output of the first positioning means when the determination means determines that the electric field strength exceeds a predetermined value and the deterioration coefficient is less than or equal to a predetermined value. And the output of the second positioning means is selected when it is determined that the electric field strength exceeds a predetermined value and the deterioration coefficient exceeds a predetermined value, and when the electric field strength is below a predetermined value. And a switching means for controlling the vehicle.