JPH0531924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data processing method for hybrid satellite navigation that calculates and displays the current position and speed of a moving object such as a car.

[Conventional technology]

Traditionally, GPS (Global Positioning
System) There is a navigation device.

In order to determine the user's position three-dimensionally using a satellite navigation device, three components in the earth-centered and earth-fixed coordinate system,
All you have to do is find the three unknowns: latitude, longitude, and height (X, Y, Z). The principle of GPS navigation equipment is to simultaneously receive and measure the distance from multiple satellites in medium-altitude orbits whose positions are known to the user. The moment-by-moment position of a satellite can be determined from orbital elements and expressed three-dimensionally. In order to find the user's three-dimensional position, if the distances from three satellites can be measured, the points of intersection of three spherical surfaces (X, Y,
Z) can be used to find the user's position.

In this way, GPS navigation equipment performs calculations using signals obtained by unidirectional propagation of radio waves from the satellite to the user. It is necessary to use two clocks that are both accurate and well-matched and to directly measure the propagation time of radio waves. However, it is not practical to equip each user with such a highly accurate clock. Therefore, the user simultaneously receives radio waves from multiple satellites and calculates the user's position based on pseudorange data including the time offset between each satellite and the user and the position data of each satellite. That is, it is necessary to add the time T that matches the satellite's clock as another unknown, and to solve the four unknowns (X, Y, Z, T) in addition to the three unknowns related to the position. To do this, it must receive radio signals from four satellites scattered in the sky. Since the height of moving objects such as automobiles does not change much, even if there is a slight error in height, the two-dimensional position of latitude and longitude is unlikely to be significantly deviated. Therefore, the height (Z) is a known value, and the three unknowns (X,
Y, T) and performs two-dimensional positioning.

When driving in areas where there are many shielding objects and radio interference between the sky and the topography and driving environment, such as mountainous areas or urban areas, where the topography and operating environment change rapidly, the 3.
It is not always possible to receive signals from 2 satellites.
In many cases, it is possible to receive signals from only a few satellites. Sometimes it may not be possible to receive it at all. For this purpose, conventional vehicles are equipped with a device (dead reckoning navigation device) that calculates the estimated position of the vehicle using a direction sensor such as a magnetic compass and a distance meter, along with a GPS navigation device. When the number of satellites that can be received becomes two or less, the vehicle's position is calculated by a dead reckoning navigation device.

Generally, GPS navigation devices have higher positioning accuracy than other navigation devices (for example, dead reckoning navigation devices). The more dispersed the satellites that are in the sky and can be received, the higher the positioning accuracy. However, the geometric precision divergence GDOP (or PDOP, which indicates three-dimensional positioning accuracy, or HDOP, which indicates horizontal precision divergence) indicates positioning accuracy.
When the position reaches a certain level or higher, the dead reckoning device has higher positioning accuracy. Even in such a reception state, the GPS navigation device suspends positioning, and the dead reckoning navigation device calculates the position of the vehicle.

[Problem that the invention seeks to solve]

When a car is driving in an area with rapid changes in topography and operating environment, the reception level of satellite signals of GPS navigation devices may drop during positioning, resulting in large errors in positioning results. Furthermore, when a car passes through a tunnel, the GPS navigation device does not perform positioning for a long period of time, and as a result of the dead reckoning navigation device performing positioning for a long period of time, an accumulated error may occur. When these events occur, the position may differ significantly from the position previously determined by the GPS navigation device.

In conventional navigation devices, positioning using GPS navigation and positioning using dead reckoning navigation were performed independently of each other and were not consistent. Therefore, there was a drawback that there was no continuity between the measured values and reliability was poor.

The present invention has been made to eliminate these drawbacks, and provides a data processing method for hybrid satellite navigation that provides continuity between each measurement value and improves reliability.

[Means for solving problems]

A data processing system for hybrid satellite navigation to which the present invention is applied in order to solve the above problems will be described below.

The data processing method of the hybrid satellite navigation of the present invention includes satellite navigation in which the position of a moving object is measured by receiving pseudorange data signals from satellites and position data signals of each satellite, and a data processing method using a direction sensor mounted on the moving object. It outputs measured values using both data and dead reckoning navigation, which measures the position of the vehicle using distance meter data. Furthermore, in the data processing method for hybrid satellite navigation of the present invention, from the geometric accuracy divergence value from the operating object to the receiving satellite and the signal level of the receiving satellite, weighting coefficients for the measured values by satellite navigation and weighting coefficients for the measured values by dead reckoning are calculated. The present invention is characterized in that it calculates a weighted average value of the measurement positions, and outputs this weighted average value as a measurement value.

The weighted average value is calculated as follows. Weighting value V ₁ (=1 to m) of the geometric precision divergence value from the operating body to the receiving satellite divided into m equal parts
And from the weighting value V ₂ (=n~1) in the order in which the signal level of the receiving satellite is divided into n equal parts, the weighting coefficient W _G = for the measured value (x _G , y _G , z _G ) by satellite navigation.
V ₁ ×V ₂ /m・n and the measured value by dead reckoning (x _D ,
_{y D , z D} ), the weighting coefficient W _D =1 _{− W G is} determined, _{and the} formula
It is obtained by taking a weighted average of z=W _G z _G + W _D z _D.

In a data processing method for hybrid satellite navigation according to another aspect of the present invention, the distance between the current measured position by satellite navigation and the previous output position by the weighted average, and the distance between the current measured position by dead reckoning and the previous output position and a weighting coefficient for the measured value by satellite navigation and a weighting coefficient for the measured value by dead reckoning navigation from both distances, take a weighted average of the measured positions, and output this weighted average value as a measured value. It is characterized by

In this data processing method for hybrid satellite navigation, weighting factors are determined as follows. The distance D _Gt1 between the satellite navigation measurement values (x _G , y _G , z _G ) and the previous output measurement value, and the dead reckoning measurement value (x _D ,
From the distance D _Dt1 between y _D , z _D ) and the previous output measurement value,
Weighting factor W _G for measurements by satellite navigation
= D _Gt1 / (D _Gt1 + D _Dt1 ) and the weighting factor for the measured value by dead reckoning W _D = D _Dt1 / (D _Gt1 + D _Dt1 )
and seek.

[Effect]

According to the present invention, the geometric accuracy divergence value indicating the positioning accuracy of the satellite navigation and the signal level of the receiving satellite that is highly correlated with the accuracy of the pseudorange data of the satellite navigation are used as parameters, and the measurement value of the satellite navigation and the dead reckoning are calculated. A value obtained by weighting and averaging the measured values is output as the measured value. Therefore, measurements using satellite navigation, which have high positioning accuracy, are normally output, but as satellite reception becomes insufficient, measurements that gradually increase the ratio of measurements using dead reckoning are output. do.

By weighting and averaging the measured values and outputting them, the measured values for each measurement by satellite navigation or the measured values by satellite navigation and the measured values by dead reckoning are matched and continuity is imparted.

〔Example〕

A data processing method for hybrid satellite navigation to which the present invention is applied will be explained using the block circuit diagram of FIG. 1 for implementing the method.

In the figure, 1 is a satellite signal receiving antenna;
2 is a receiving section, 3 is a GPS calculation processing section, 4 is a control section,
5 is a position display operation section, 6 is a positioning data calibration section, 7
8 is a magnetic compass which is a direction sensor, 9 is a distance meter, and 10 is a car equipped with these devices.

The operation will be explained below.

The GPS navigation device starts positioning operation when the initial position, date, and time of the automobile 10 are input to the position display operation section 5. The input initial position data of the automobile 10 is transferred to the control section 4. Based on this, the control section 4 selects a satellite to be used for positioning, and instructs the receiving section 2 to receive the selected satellite. Upon receiving this command, the receiver 2 demodulates the satellite signal sent from the antenna 1 and measures the pseudo range of the satellite. The receiving unit 2 then sends the satellite navigation message data and the satellite pseudorange data to the GPS arithmetic processing unit 3. The arithmetic processing unit 3 counts the position of the automobile 10 based on these data. On the other hand, the magnetic compass 8 detects the traveling direction of the automobile 10 and inputs the detected direction to the estimated position calculating section 7 as azimuth data. The distance meter 9 detects the number of rotations of the wheels and inputs it to the estimated position calculating section 7 as travel distance data.
The estimated position calculation unit 7 calculates the location of the vehicle 1 from these data.
Calculate the estimated location of 0. In this way GPS
Navigation and dead reckoning each provide a measured position.

The signal level of the receiving satellite and the geometric precision divergence value (GDOP,
PDOP, HDOP) are sent. Using these as parameters, the positioning data calibration section 6 calculates a weighted average value of the measured position by GPS navigation and the measured position by dead reckoning navigation, and sends this value to the position display operation section 5 as output data. Then, in the position display operation section 5, the vehicle 1 is
Outputs the 0 position.

The weighted average value of the position measured by GPS navigation and the measured position by dead reckoning navigation is determined by the positioning data calibration unit 6 as follows.

Factors that affect the positioning accuracy of GPS navigation include geometric precision divergence (GDOP, PDOP,
HDOP) and pseudorange data accuracy.
The accuracy of pseudorange data has a high correlation with the signal level of the receiving satellite. Therefore, we will replace the accuracy of the pseudorange data with the signal level of the receiving satellite.

The highest value of the geometric precision divergence is set to 20, and this is divided into 10 equal parts (for example, PDOP = 20, 18, 16, ... 2).
Weighting value V ₁ (1, 2, 3, ..., 10) in that order
(For example, when PDOP=2, V ₁ =10).

In addition, the signal level of the receiving satellite is divided into 10 equal parts from the highest value to the lowest value, and weighting values V ₂ are assigned in order from the highest value to the lowest value.
are given as 10, 9, 8, ..., 1. weighting value
V ₂ is calculated from the reception level of the satellite that is receiving at the lowest level among the receiving satellites. At this time, the weighting coefficient W _G of the measured position in GPS navigation is given as w _G =V ₁ ×V ₂ /100. Moreover, the weighting coefficient W _D of the measurement position in dead reckoning is given as w _D =1−w _G.

Here, let the XYZ coordinate axes positions of the measured position by GPS navigation be x _G , y _G , z _G , and the measured position by dead reckoning navigation.
When the XYZ coordinate axis positions are x _D , y _D , z _D , the XYZ coordinate axis position of the positioning output data by the positioning data calibration unit 6 is: x=w _G x _G +w _D x _D y=w _G y _G +w _D y _D It can be found as z=w _G z _G + w _D z _D.

If the weighting value V ₂ of the signal level of the receiving satellite and the weighting value V ₁ of the geometric accuracy divergence value are both 10, then
The vehicle 10 position in dead reckoning will be updated by the measured position in GPS navigation.

In this way, the positioning output is displayed without large errors, and even when GPS navigation positioning is interrupted, the output data of the 10 car positions using only dead reckoning still remains the same as the highly accurate positioning of the GPS navigation device. Since it is updated with data, there are fewer errors.

In another embodiment, the positioning data calibration unit 6
The weighted average value of the GPS navigation measurement position and the dead reckoning navigation measurement position is determined by the following method.

Let the X, Y, and Z coordinate axes positions of the previous positioning output data by the positioning data calibration unit 6 be x _t0 , y _t0 , z _t0 ,
The coordinate axis position of the current measurement position by GPS navigation
Let x _Gt1 , y _Gt1 , z _Gt1 be the coordinate axis positions of the current measurement position by the dead reckoning device as x _Dt1 , y _Dt1 , z _Dt1 .
At this time, the distance D Gt1 between (x _Gt1 , y _Gt1 , z _Gt1 ) and x _t0 , y _t0 , z _t0 ) and the distance D _Gt1 between (x _Dt1 , y _Dt1 , z _Dt1 ) and (x _t0 ,
y _t0 , z _Gt1 ) respectively _.

D _Gt1 =√( _Gt1 − _t0 ) ² + _Gt1 − _t0 ) ² + ( _Gt
1 − _t0 ) ² D _Dt1 = √( _Dt1 − _t0 ) ² + ( _Dt1 − _t0 ) ² + (
_Dt1 − _t0 ) ² where the weighting factor W _G of the measured position in GPS navigation
is W _G = D _Dt1 / (D _GT1 + D _Dt1 ), and the weighting factor for the measured position of the dead reckoning device is
W _D is set as w _D = D _Gt1 / (D _GT1 + D _Dt1 ).

There is no particular change in how the positioning data calibration unit 6 calculates the XYZ coordinate axis position of the positioning output data from these weighting coefficients W _G and W _D .

〔Effect of the invention〕

As explained above, in the data processing method of hybrid satellite navigation to which the present invention is applied, the measured values of each measurement by satellite navigation, or the measured values of satellite navigation and the measured values of dead reckoning, match each other,
Continuity is given. Therefore, the positioning output data that is outputted is continuous and highly reliable, making it ideal for applications such as automobiles that drive in areas with rapid changes in topography and driving environment.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram for implementing a data processing system for hybrid satellite navigation to which the present invention is applied. DESCRIPTION OF SYMBOLS 1... Satellite signal receiving antenna, 2... Receiving unit, 3... Arithmetic processing unit, 4... Control unit, 5... Position display operation unit, 6... Positioning data calibration unit, 7...
Estimated position calculation unit, 8...Magnetic compass, 9...Distance meter, 10...Car.

Claims (1)

[Claims] 1. Satellite navigation that measures the position of a moving object by receiving pseudorange data signals from satellites and position data signals of each satellite, and data from a direction sensor mounted on the moving object and a distance meter. In hybrid satellite navigation, which outputs measured values by both dead reckoning, which measures the position of the moving object using data, the measured value by satellite navigation is calculated from the geometric accuracy divergence value from the moving object to the receiving satellite and the signal level of the receiving satellite. 1. A data processing method for hybrid satellite navigation, characterized in that a weighted coefficient for a measured value by dead reckoning navigation is calculated, a weighted average of the measured positions is calculated, and this weighted average value is outputted as a measured value. 2. In the data processing method for hybrid satellite navigation according to claim 1, the distance between the current measured position by satellite navigation and the previous output position by the weighted average, and the distance between the current measured position by dead reckoning navigation and the previous output position Find the distance from the output position of A data processing method for hybrid satellite navigation characterized by output.