JPH0827341B2 - GPS navigation device - Google Patents

Description

The present invention relates to calculation processing and display of user speed in GPS navigation.

[Conventional technology]

GPS navigation uses radio waves from multiple satellites operating in polar orbits to determine the position of each satellite and the pseudo range and pseudo range rate between itself and each satellite. This is a navigation method that calculates and calculates speed and traveling direction.

Then, these calculated values are used for display, control value and the like (in this invention, referred to as "display etc.").

The pseudo range is an apparent distance between the satellite and the user, that is, a distance including a true distance and a distance to be corrected, and the distance to be corrected is mainly based on the clock offset. Therefore, the following calculation is performed here as “distance + (light speed × clock offset)”.

Also, the rate of change of the pseudo range per unit time is the pseudo range rate, and the "time difference" between the satellite clock and the user clock is the clock offset. Is the clock offset rate.

In the following description, each symbol is marked with
For example, a code such as x is a code representing a differential value with respect to time of the object of the code, as in the case of the code used in a general velocity equation or the like.

Now, as a coordinate system, a Cartesian coordinate system of the earth center and the earth is fixed (in the present invention, referred to as a geocentric orthogonal coordinate system), user coordinates are Ux, Uy, Uz, and satellite coordinates are Xi, Yi, Zi (1
≦ i ≦ n). There is a relationship between the pseudo range PDi (distance + C, clock offset B) and coordinates with each satellite, which is measured using radio waves, by the following equation.

(Xi-Ux) ² + (Yi-Uy) ² + (Zi-Uz) ² = (PDi + C ・ B) ² …………
(1) where C is the speed of light and B is the clock offset. PD
If the measured value of i is represented as MSRi, the following simultaneous position equations are generally obtained when four satellites are captured.

(MSR ₁ + C ・ B) ² = (X ₁ -Ux) ² + (Y ₁ -Uy) ² + (Z ₁ -Uz) ² (MSR ₂ + C ・ B) ² = (X ₂ -Ux) ² + (Y ₂ -Uy) ² + (Z ₂ -Uz) ² (MSR ₃ + C ・ B) ² = (X ₃ -Ux) ² + (Y ₃ -Uy) ² + (Z ₃ -Uz) ² ( MSR ₄ + C ・ B) ² = (X ₄ -Ux) ² + (Y ₄ -Uy) ² + (Z ₄ -Uz) ² ......
…… (2) Differentiating both sides of equation (2) with respect to time, i = 1,2,
We obtain the following equations for 3 and 4.

(MSRi + C ・ B) ・ MSRDi = (Xi-Ux) ・ (ix) + (Yi-Uy) ・ (iy) + (Zi-Uz) ・ (iz) ………… (3) where MSRDi Is the derivative of MSRi with respect to time, which is also obtained from the measurement.

In equation (3), x, y, z, are variables, and all others are known (some are obtained by solving equation (2)). A simultaneous velocity equation is obtained.

A ・ = D ………… (4) However, In GPS navigation, the simultaneous position equations shown in Eq. (2) are solved to obtain Ux, Uy, Uz, B, and these values are used to construct the simultaneous velocity equation shown in Eq. (3), which is solved. X, y,
Find z ,. In the above formula, MSRi is represented by Ri.

When the number of acquired satellites is 3 or less, it is effective to use virtual satellites as the insufficient number of satellites.
A method using such a virtual satellite is disclosed in Japanese Patent Application No. 61-280647 (Japanese Patent Laid-Open No. 63-134975) filed by the present applicant.

[Problems to be Solved by the Invention]

When the user is a vehicle traveling on the ground using the above GPS navigation device, the velocity V, the azimuth VAZ and the elevation VEL in the traveling direction of the user (in the present invention, the user velocity V, the user azimuth VAZ and It would be extremely convenient if a device that can obtain the user elevation angle VEL) by a simple calculation is provided, and at a measurement location where only three satellites can be captured, a virtual satellite is set for measurement. It would be even more convenient if a device capable of easily performing such setting and calculation of virtual satellites was provided, and there is a problem of how to configure the calculation in such a device to provide a more effective one.

[Means for solving the problem]

The present invention is based on the user position (Ux, Uy, Uz) and the satellite position (Xi, Yi, Z) calculated from the orbit parameters obtained from each satellite.
The satellite velocity (i) obtained by dividing the difference between the current value of i) and the value at the previous measurement time or at the time ΔT before the current measurement time by this measurement time interval TI or the previous measurement time interval ΔT. , i, i) and the like, the user velocity (x,
y, z) and the horizon rectangular coordinate system calculated by converting the geocentric rectangular coordinate system to the horizon rectangular coordinate system at latitude LT and longitude LG corresponding to the user position (Ux, Uy, Uz). Based on user speed (x, y, z)
User speed V, user azimuth VAZ and user elevation VEL are obtained, and when there are three satellites, the user's altitude (HT) and time offset rate () are assumed to be locally constant. User velocity (x, y, z) is calculated by the position equation and the three-dimensional simultaneous velocity equation, or a four-dimensional simultaneous positional equation is added by adding the position equation with the virtual satellite at the center of the earth, and the four-dimensional simultaneous equation is constructed. The above problem is solved by configuring the user speed (x, y, z) to be calculated by a simultaneous speed equation.

〔Example〕

 Embodiments will be described below with reference to the drawings.

As shown in FIG. 4, the configuration of the GPS navigation device of the present invention is composed of a satellite navigation receiving unit 1, an arithmetic processing unit 2, a display unit 3, and the like.

The arithmetic processing unit 2 includes a CPU 23 and a program memory (RO
Memory 24 including M) and temporary memory (RAM), and processed latitude LT, longitude LG, height (HT), clock offset (B), user speed V, user azimuth VAZ, user elevation V
A data memory (RAM) 25 for storing numerical values such as EL is provided. Here, it is not necessary to physically divide the RAM memory into the above memory units.

Further, the arithmetic processing unit 2 has an input port 21 for receiving inputs from the console 20 for setting initial values and the satellite navigation receiving unit 1, and an output port 22 for outputting the result of arithmetic processing. And are provided.

The arithmetic processing unit 2 obtains the reception data from the satellite navigation receiving unit 1 and performs the arithmetic processing as described below, so that the user coordinate data and the user speed data, the clock offset, and the clock can be received until the next reception. Data such as offset rate is obtained and stored in the data memory 25.

Then, when processing the next received data, by using the data stored in the data memory 25 as an estimated value, the user position can be calculated continuously, and the target arithmetic processing can be performed from this user position. The result of performing is displayed on the display unit 3 by a numerical display or a graphical display method as shown in FIG.

The satellite navigation receiving unit 1 gives the measured value MSRi of the pseudo range PDi to and from the satellite and the measured value MSRDi of the pseudo range rate PDRi, as well as information data such as orbital parameters necessary for calculating the satellite position and the user clock. And outputs the time information and the like to the arithmetic processing unit 2.

Then, the arithmetic processing in the arithmetic processing unit 2 is mainly performed based on each of the following operations (a) to (d).

(A) Using the orbital parameters obtained from the satellite, calculate the geocentric Cartesian coordinate values (Xi, Yi, Zi) of the satellite position at the measurement time,
Furthermore, the coordinate value (XPi, YPi, ZPi) of the satellite position at the time earlier by ΔT than the previous measurement time or this measurement time is saved or calculated, and the difference between them (Xi-XPi, Yi-YPi, Zi). −
ZPi), and divide them by the measurement time interval TI or ΔT of this time and the previous time to obtain satellite velocity (i, i, i), and solve the simultaneous equations (2) in the geocentric Cartesian coordinate system. User position (Ux, Uy, Uz) and clock offset (B)
And a pseudo-range PDi measurement value MSRi obtained from the measurement and a pseudo-range late PDRi measurement value MSPDi to construct a four-way simultaneous velocity equation (equation (4) above), and solve it to obtain the geocentric orthogonal coordinates. An operation for obtaining the user speed (x, y, z) and the clock offset rate () in the system.

(B) Converting the coordinate system from the geocentric orthogonal coordinate system to a horizon orthogonal coordinate system in which the zenith at the user position is the Z axis, north and south is the X axis, and east and west is the Y axis, and the user speed is the geocentric orthogonal coordinate system. Calculated by converting from the user speed (Ux, Uy, Uz) in the system to the user speed (x, y, z) in the horizontal rectangular coordinate system, and calculate the user speed V, the azimuth angle VAZ in the traveling direction, and the elevation angle VEL. VAZ = ATAN (-y / x) VEL = ASIN (z / V) is calculated, VAZ, VEL is converted into degrees, and the operation is rounded to below degrees.

(C) If three satellites cannot be captured, it is assumed that the user's altitude (HT) and clock offset rate () are almost constant (often) near the measurement time, that is, Altitude (HT) assuming constant locally
By applying the previous measured value or estimated value to, the user position (Ux, Uy,
Uz) and clock offset (B) are calculated, and the clock offset rate () is calculated by dividing the difference between the current clock offset (B) and the previous clock offset (B) by the measurement time interval TI. An operation that constructs a ternary simultaneous velocity equation regarding velocity (x, y, z) and solves it to obtain user velocity (x, y, z) in the geocentric Cartesian coordinate system.

In addition, in the case of this calculation, since the calculation is performed assuming that the altitude HT of the user is constant, even if the elevation angle VEL is calculated,
It is natural that it cannot be put to practical use, and no explanation is required.

(D) As a fourth satellite, a virtual satellite is placed in the center of the earth, and the position (X ₄ , Y ₄ , Z ₄ ) and speed ( ₄ , ₄ , _4, ) of the virtual satellite are all zero, and the pseudo range rate is set. The measurement location of MSPD ₄ is
The pseudo range PD ₄ for the temporary satellite is set by the user position (Ux, Uy, Uz), the clock offset (B) and the speed of light C. The difference between the current value and the previous value obtained by the value obtained by dividing the current and previous time interval TI, a virtual satellite measurements MSRD ₄
Construct a four-way simultaneous velocity equation added as, solve it, and solve it to calculate the user velocity (x,
y, z) and clock offset rate () calculation.

Then, by these calculations, the user position (Ux, Uy, Uz) and the clock offset (B) are obtained from the simultaneous position equation in the geocentric Cartesian coordinate system, and the simultaneous velocity equation in the same coordinate system is calculated using these values. After constructing and solving it to obtain the user velocity (x, y, z) in the same coordinate system, the latter is converted from the geocentric Cartesian coordinate system to the Horizon Cartesian coordinate system in the user position. The user speed (x, y, z) in the coordinate system of is obtained, and these are used to finally calculate the user speed V, the user azimuth angle VAZ and the user elevation angle VEL on the ground, which are required by the user. It is configured so that the value can be used for a required display or the like.

First, each calculation process will be described with reference to the flowcharts of FIGS. 1 and 2.

As can be seen from the contents, the portions (P0) to (P6) of FIG. 1 are described in the above-mentioned Japanese Patent Application No. 61-280647 (Japanese Patent Laid-Open No. 63-13497).
The same arithmetic processing as described in 5) is performed, and the following arithmetic processing is performed.

In (P0), when four or more acquisition satellites are obtained, it is selected so as to acquire four satellites that can obtain the optimum pseudo range PDi.

In (P1), satellite coordinates X based on the selection in (P0)
i, Yi, Zi: i = 1 to 4 is calculated, and pseudo range measurement value MSRi: i =
Enter 1-4. Here, the former is calculated by another routine using the orbit parameter data of each satellite and the user clock, and the latter is the value obtained from the receiver.

In (P2), when the number of captured satellites is 3, a virtual satellite is placed at the center of the earth as a satellite corresponding to i = 4, and MSR ₄ is calculated from the estimated position. In other words, the value obtained by calculating the pseudo range of the virtual satellite placed at the center of the earth from the user estimated coordinates is the provisional pseudo range measurement value MSR ₄ for the _fourth satellite.

In (P3), latitude LT, longitude LG, and height H of the estimated user position
A quaternary simultaneous equation in the geocentric coordinate system is constructed from T and the clock offset B, and the equations are solved to calculate the correction values of the user positions Ux, Uy, Uz and the clock offset B.

In (P4), the latitude LT, the longitude LG, the height HT, and the clock offset B of the user estimated position are corrected by the solution obtained in (P3), that is, the correction value. However, when there are three captured satellites, that is, when (P2) is performed, the height HT is not corrected.

In (P5), the pseudo range PDi is calculated from the solution obtained in (P4), that is, the latitude LT, the longitude LG, the height HT, and the clock offset B of the corrected user estimated position.

In (P6), it is examined whether the absolute value difference ABS (PDi-MSRi) between the pseudo range PDi and the pseudo range measured value MSRi by the above calculation is within the minute difference EPS, and the minute difference EPS
If it is not within the range, it moves to the next (P7), and if it is not within the minute difference ESP, it returns to the original (P2).

In (P7), if the number of acquired satellites is 4 or 3,
Move to the processing enclosed by the frame on the left or right of the next (P8), and if the number is 2 or less, the speed cannot be obtained, so skip the calculation in the middle and select to go to the end.

In (P8), the same satellite coordinates Xi, Yi, Z as in (P2)
i: i = 1 to 4 or i = 1 to 3 is set to ΔT: 1 from the measurement time T depending on the orbit parameter sent from the satellite.
It is calculated for a time before by a small value less than a second, i ← {Xi (T) −Xi (T−ΔT)} / ΔT i ← {Yi (T) −Yi (T−ΔT)} / ΔT i ← { The satellite velocity (i, i, i) is calculated by Zi (T) −Zi (T−ΔT)} / ΔT.

Instead of recalculating Xi, Yi, Zi for T-ΔT,
Xi, Yi, Zi at the last measurement time is stored as PXi, PYi, PZi, and using this and the last measurement interval TI, i ← {Xi (T) −PXi} / TI i ← {Yi (T) -PYi} / TI i ← {Zi (T) -PZi} / TI. Pseudo range rate measurement MSRD
i is read from the measured value.

In the next (P9), A (I, 1), A (I, 2), A (I, 3), A (I, 4) and D (I) in the above simultaneous velocity equation (4) are ,
It is constructed by the calculated value and the measured value obtained by the processing so far.

When the number of captured satellites is 3, assuming that the clock offset rate () is locally constant, the simultaneous velocity equation is changed from the quaternary equation (4) to the ternary equation (4) ′. Build things.

A ・ = D ……………… (4) ′ However, In the above formula, MSRi is represented by Ri.

Here, () is the current clock offset (B) and the previous clock offset (BP) obtained by the simultaneous position equations.
Divided by the measurement time interval TI of this time and last time {B (T)
-BP} / TI is applied. 4 yuan or 3 constructed here
The original simultaneous equations are solved by the following (P10), and the user velocity (x, y, z) and the clock offset rate () in the geocentric Cartesian coordinate system are obtained.

In the next (P11), the coordinate system is changed to the user position (latitude LT, longitude).
LG), the zenith is the Z-axis, the north-south direction is the X-axis, and the east-west direction is Y.
User speed when converted to the horizon rectangular coordinates as the axis (
x, y, z) is calculated from (x, y, z) and (LT, LG).

In the next (P12), the velocity, the azimuth angle VAZ and the elevation angle VEL in the traveling direction are calculated from the user velocity (x, y, z) in the horizontal coordinate system by the following formulas.

VAZ = ATAN (-y / x) VEL = ASIN (z / V) (P13) converts V from meter / second to kilometers / hour, and converts VAZ, VEL from radian to degree.
Round 0.1kM / H or less, VAZ, VEL less than 1 degree, and cut the meaningless numerical part.

In (P14), speed V, azimuth VAZ in the traveling direction and elevation VE
L, the clock offset rate () is displayed as a numerical value or a three-dimensional image graphic as illustrated in FIG.

The flowchart of FIG. 2 replaces the parts P8, P9, and P10 of FIG. 1, and the processing here is performed as follows.

In (P8 '), if there are four acquisition satellites, the processing is exactly the same as in (P8), but if there are three acquisition satellites, the position equation for the virtual satellite placed in the earth's center is used. Make the fourth velocity equation. Pseudo-range rate for virtual satellites: MSRD ₄ cannot be obtained as a measured value, so pseudo-range: The difference between this value and the previous value PD ₄ P
Value divided by TI: (PD ₄ − PD ₄ P) / TI is applied to MSRD ₄ . Since the virtual satellite is fixed to the earth's center, naturally X ₄ , Y ₄ , Z ₄ , ₄ ,
₄ and ₄ are all zero.

The following (P9 ') and (P10') are (P9) and (P10) in Fig. 1.
Is exactly the same as the left part of. Because (P8 ')
This is because the velocity equations are unified into the quaternion by the process of, and only the process of solving the quaternary velocity equation is required thereafter.

However, when there are three satellites, the position equation is constructed under the condition that there is no change in altitude (HT), so the elevation angle VEL in the traveling direction is set to zero instead of being calculated.

Therefore, in the case of capturing 4 satellites for arithmetic measurement and in the case of capturing 3 satellites and providing 4 virtual satellites by providing 1 virtual satellite, satellite measurement is performed as described above. The clock offset rate () can be obtained by the simultaneous equations of four elements.

On the other hand, when calculating and measuring only the three satellites captured, the clock offset rate () cannot be calculated, so the difference between the current value of the clock offset (B) and the previous value is measured at the measurement time. By using the expedient method in which the value divided by the interval TI is used as the clock offset rate (), it is possible to perform arithmetic measurement by the three-dimensional simultaneous position equation.

〔The invention's effect〕

According to the present invention, as described above, whether four satellites can be captured or only three satellites can be captured, the four-dimensional simultaneous velocity equation or the three-dimensional simultaneous equation in the geocentric Cartesian coordinate system is correspondingly adjusted. By easily constructing the velocity equation, solving it, and converting it to the user velocity in the horizontal rectangular coordinate system,
Since the azimuth angle and the elevation angle required by the user in the traveling direction and the traveling direction can be easily obtained, the calculation configuration can be made relatively simple, and the required display can be performed by these calculation values. Other required values can be obtained based on the value of, and it is possible to provide a GPS navigation device that is extremely convenient for users traveling on the ground.

[Brief description of drawings]

The drawings show embodiments, FIG. 1 is a flowchart of arithmetic processing, FIG. 2 is a flowchart of a modified portion of arithmetic processing, FIG. 3 is a display image diagram in the case of performing a graphical display, and FIG. 4 is a block of an apparatus. It is a block diagram. 1 ... Satellite navigation receiving unit, 2 ... Calculation processing unit, 3 ... Display unit, 20 ... Operation console, 21 ... Input port, 22 ... Output port, 23 ... CPU, 24
…… Memory, 25 …… Data memory.

Claims (3)

[Claims] 1. The position information of each satellite obtained by capturing four satellites, the measured value MSRi of the pseudo range PDi between each satellite, and the measured value MSRDi of the pseudo range rate PDRi, It has an arithmetic processing unit for calculating and displaying the user speed V, the user azimuth angle VAZ, and the user elevation angle VEL based on the four-element simultaneous position equation and the four-element simultaneous velocity equation in the geocentric orthogonal coordinate system. A GPS navigation device, a. The user position (U
x, Uy, Uz) and clock offset (B), and the satellite position (X
i, Yi, Zi) was calculated by dividing the difference between the current value of i, Yi, Zi) and the value at the previous measurement time or at the time ΔT before the current measurement time by the current and previous measurement time interval TI or ΔT. Satellite velocity (i, i, i) and the pseudo range rate PDRi
According to the four-dimensional simultaneous velocity equation constructed using the measured value MSRDi of the user velocity (x,
y, z) first computing means, b. the geocentric Cartesian coordinate system, the user position (Ux, Uy, Uz)
Corresponding to the latitude LT and longitude LG zenith is the Z axis, north and south is the X axis,
Second computing means for calculating a user speed (x, y, z) in the horizon orthogonal coordinate system from the user speed (x, y, z) by converting it into a horizon rectangular coordinate system having east and west as the Y axis And c. The user speed V, the user azimuth angle VAZ, and the user elevation angle VEL based on the user speed (x, y, z). VAZ = ATAN (-y / x) VEL = ASIN (z / V) and a third calculation means for calculating the GPS navigation device. 2. The position information of each satellite obtained by capturing three satellites, the measured value MSRi of the pseudo range PDi with each satellite, and the measured value MSRDi of the pseudo range rate PDRi, A GPS navigation device having an arithmetic processing unit for calculating and displaying a user speed V and a user azimuth angle VAZ based on a three-dimensional simultaneous position equation and a three-dimensional simultaneous velocity equation in a geocentric Cartesian coordinate system. A. Assuming that the user's altitude (HT) and time offset rate () are locally constant, the user position (Ux, Uy, Uz) and clock offset (B) are calculated by the three-way simultaneous position equation. And the difference between the current value and the previous value of the clock offset (B) divided by the measurement time interval TI as the clock offset rate (), and the user position (determined by the three-dimensional simultaneous position equation) Ux, Uy, Uz) and each of the above Satellite position calculated by the trajectory parameters obtained from (X
i, Yi, Zi) was calculated by dividing the difference between the current value of i, Yi, Zi) and the value at the previous measurement time or at the time ΔT before the current measurement time by the current and previous measurement time interval TI or ΔT. Satellite velocity (i, i, i) and the pseudo range rate PDRi
First calculation means for calculating the user speed (x, y, z) in the Cartesian coordinate system by constructing the three-dimensional simultaneous velocity equation constructed using the measured value MSRDi of b. The geocentric Cartesian coordinate system, the user position (Ux, Uy, Uz)
Corresponding to the latitude LT and longitude LG zenith is the Z axis, north and south is the X axis,
Second computing means for calculating a user speed (x, y, z) in the horizon Cartesian coordinate system from the user speed (x, y, z) by converting the east-west direction into a horizon rectangular coordinate system And c. The user speed V, the user azimuth angle VAZ, and the user elevation angle VEL based on the user speed (x, y, z). A third navigation means for calculating VAZ = ATAN (-y / x), and a GPS navigation device. 3. The user acquires three satellites, and
Assuming a fourth provisional satellite, the position information of each satellite and the measured value MSRi of the pseudo range PDi between each satellite
And the measured value MSRDi of the pseudo range rate PDRi, the user speed V and the user azimuth VAZ are calculated based on the four-element simultaneous position equation and the four-element simultaneous velocity equation in the geocentric Cartesian coordinate system.
And a GPS navigation device having an arithmetic processing unit for calculating a user elevation angle VEL and displaying the same. A. The quaternary including the virtual satellite placed in the earth's center and the position equation by the virtual satellite added. Equation building means for building simultaneous position equations, and b. User positions (Ux, Uy, Ux, Uy, Z4) obtained by the four-dimensional simultaneous position equations by setting all virtual satellite positions (X ₄ , Y ₄ , Z ₄ ) to zero. Uz), the clock offset (B), and the speed of light C, the value PD ₄ of the pseudo range PDi for the virtual satellite is calculated. The value obtained by dividing the difference between the present value and the previous value by the time interval TI of the present time and the previous time, the measured value MSRD ₄ corresponding to the measured value MSRDi of the pseudo range rate PDRi of the virtual satellite.
Virtual satellite computing means, c. The user position (Ux, Uy, Uz) and the clock offset (B), and the satellite position (Xi, Yi, Zi) calculated by the orbit parameter obtained from each satellite. Satellite velocity (i, i, i) obtained by dividing the difference between the current value and the previous measurement time or the value at the time ΔT before the current measurement time by this measurement time interval TI or the above ΔT. i) and the virtual simultaneous velocity equation constructed using the measured value MSRDi, the user velocity (x, y,
z) first computing means, d. the geocentric Cartesian coordinate system, the user position (Ux, Uy, Uz)
Corresponding to the latitude LT and longitude LG zenith is the Z axis, north and south is the X axis,
Second computing means for calculating a user speed (x, y, z) in the horizon orthogonal coordinate system from the user speed (x, y, z) by converting it into a horizon rectangular coordinate system having east and west as the Y axis And e. The user speed V, the user azimuth angle VAZ, and the user elevation angle VEL based on the user speed (x, y, z). VAZ = ATAN (-y / x) VEL = ASIN (z / V) and a third calculation means for calculating the GPS navigation device.