KR100341801B1 - Urban vehicle navigation system using multiple antennas - Google Patents

Abstract

end. FIELD OF THE INVENTION The present invention relates to a vehicle navigation system.

I. The present invention has been made in an effort to provide an urban vehicle navigation system capable of detecting and correcting a multipath error.

All. SUMMARY OF THE INVENTION: An urban vehicle navigation system using multiple antennas, comprising: receiving a satellite signal from a GPS (Global Positioning System) satellite via a plurality of antennas, and measuring a pseudo-range measurement value (P_ {SV_i) for each antenna , A_j}) and a multi-antenna satellite signal receiver for calculating and outputting a carrier phase measurement value (Φ_ {SV_i, A_j}), a navigation sensor unit for detecting a rotation angle and a speed of a driving vehicle and outputting the navigation sensor information; A measurement error detection unit for inputting the navigation sensor information, the pseudo distance measurement value and the carrier phase measurement value to output only the pseudo distance measurement value and the carrier phase measurement value except for the measurement values including the multipath error, and the output and navigation sensor information of the measurement value error detection part And a navigation calculator for calculating and outputting driving information of the vehicle by receiving the received signal, and surrounding ground based on the driving information. And the map information, characterized in that it consists of a control unit that reads and displays the map data storage unit.

la. Significant Uses of the Invention: Can be used in vehicle navigation systems.

Description

Urban Vehicle Navigation System Using Multiple Antennas

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle navigation system, and more particularly, to an urban vehicle navigation system using multiple antennas to reduce errors of satellite signals due to interference and reflection and to provide a more accurate position, speed, and direction angle in a crowded city. .

The vehicle navigation system announced by 日本 田 技術 硏 in 1981 has been rapidly spreading as the electronic map became commercialized by Toyota Motor Company in 1987.

Typical vehicle navigation systems are provided by the Dead Reckoning System using information provided by the Satellite Navigation System (GPS), GLONASS, and other speed and orientation sensors mounted on the vehicle. The information is used to calculate the speed, orientation and location of the vehicle. The calculated position is displayed on a display unit such as a CRT or LCD along with a map read from the map data storage device. Navigation devices are integrated with technologies such as satellite signal and navigation sensor signal processing, map data processing and filtering techniques, and the methods themselves are diverse.

In general, the position of the vehicle is obtained by appropriately combining the position provided by the dead reckoning device and the position provided by the satellite navigation device, because the two systems have opposite characteristics. The dead reckoning device provides relatively accurate position change information for a short time but diverges with time. Satellite navigation systems, on the other hand, provide absolute location information but have a relatively large position error of up to 100m. Therefore, in recent years, a map matching method and the like have been widely used along with a differential correction system for error correction of a satellite navigation system.

The error factors of vehicle navigation system can be largely divided into satellite navigation error and dead reckoning error. Satellite navigation errors include SA errors, ionospheric delay errors, and multipath errors. The SA components and the ionospheric delay errors, which have the largest component, can be corrected using correction information transmitted from a local station. The multipath error is an error generated when the satellite signal is reflected by a nearby building or object and transmitted to the receiver. The multipath error cannot be corrected by correction information, and is particularly severe in an urban area with many tall buildings. Therefore, when a multipath error occurs, it is difficult to determine which road the vehicle is on in an area where the roads are concentrated.

The dead reckoning system does not require external signals and can therefore be effectively used in urban areas. The error of the dead reckoning system is mainly due to the error that occurs in the navigation sensor. The main cause is the gyro and odometer which are frequently used as the navigation sensor. In particular, in the case of a gyro, azimuth information of the vehicle is provided. In the case of a gyro used in a vehicle navigation system, its accuracy is low, and thus a large error occurs when used without correction.

In the case of the satellite navigation system using multiple antennas, it is possible to calculate the azimuth angle of the vehicle using the difference of the carrier phase measurement value, and it is possible to correct the gyro of the dead reckoning system. However, if the carrier phase measurement includes a multipath error, an incorrect azimuth angle is obtained, which also reduces the reliability of the dead reckoning system.

As described above, the multipath error affects the position error and the azimuth error, thereby lowering the reliability of both the position and the orientation information provided by the satellite navigation system and the dead reckoning system during urban driving.

The general multipath error affects both the pseudo range measurement used for positioning and the carrier phase measurement for velocity determination and azimuth calculation. Fatal errors can occur in navigation systems. This multipath error is caused by the satellite signal being reflected on the building or object and receiving the signal through a path other than the straight path from the satellite. If the direction of the satellite signal is different, the distance to the satellite received from each antenna will show different values than expected. In particular, this phenomenon is large when a satellite signal in a straight line is received at one antenna and a signal including a multipath error is received at another antenna. This is because the carrier phase measurement used to detect the movement of the antenna is also greatly influenced by the direction in which the satellite is received.

Accordingly, an object of the present invention is to provide an urban vehicle navigation system capable of detecting and correcting multipath errors.

It is still another object of the present invention to determine whether a multipath error is included using pseudorange measurements and carrier phase measurements at each antenna when the direction of the satellite signal is different, such as a satellite signal including a multipath error. The present invention provides an urban vehicle navigation system that can be excluded from positioning, velocity, and azimuth calculations.

In the present invention for achieving the above object is a city-type vehicle navigation system using multiple antennas,

Receives a satellite signal from a GPS (Global Positioning System) satellite through a plurality of antennas, and calculates and outputs a pseudo range measurement value (P_ {SV_i A_j}) and a carrier phase measurement value (Φ_ {SV_i A_j}) for each antenna. An antenna satellite signal receiver,

Navigation sensor unit for detecting the rotation angle and the speed of the vehicle driving and outputting the navigation sensor information,

A measurement error detection unit for inputting the navigation sensor information, the pseudo distance measurement value and the carrier phase measurement value to output only the pseudo distance measurement value and the carrier phase measurement value except for the measurement values including the multipath error;

A navigation calculator configured to receive the output of the measurement error detector and navigation sensor information to calculate and output driving information of the vehicle;

The controller may be configured to read out and display map information of a surrounding area based on the driving information from a map data storage unit.

1 is a block diagram of a general vehicle navigation system.

2 is a block diagram of an urban vehicle navigation system according to an exemplary embodiment of the present invention.

3 is a block diagram of a multi-antenna satellite signal receiver 22 of FIG.

4 is a configuration diagram of the measurement error correction unit 24 in FIG. 2.

5 is an exemplary coordinate diagram for defining a coordinate system and an antenna position according to an embodiment of the present invention.

Hereinafter, the configuration and operation of an urban vehicle navigation system using multiple antennas according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 is a block diagram of a general vehicle navigation system, FIG. 2 is a block diagram of an urban vehicle navigation system according to an embodiment of the present invention, and FIG. 3 is a block diagram of a multi-antenna satellite signal receiver 22 of FIG. As shown in FIG. 4, FIG. 4 illustrates a configuration diagram of the measurement error detection unit 24 of FIG. 2. And FIG. 5 illustrates a coordinate example for defining a coordinate system and an antenna position according to an embodiment of the present invention.

1 and 2, the urban vehicle navigation system according to an exemplary embodiment of the present invention uses a multi-antenna satellite signal receiver 22, a measurement error detector 24, and a navigation calculator 14 that are different from a general vehicle navigation system. Equipped. The multi-antenna satellite signal receiver 22, the measurement error detector 24, and the navigation calculator 14 may be configured as one board or may be separately configured as necessary.

Referring to FIG. 2, the multi-antenna satellite signal receiver 22 includes a plurality of antennas and the same number of RF receivers 30, 32, and 34 as shown in FIG. 3. The RF receiver 1, 2, 3 (30, 32, 34) converts the satellite signal received from the antenna into IF (Intermediate Frequency) using an appropriate mixer and filter and performs sampling. The signal converted by each of the RF receivers 1, 2, 3 (30, 32, 34) is then output to the multi-channel digital signal processor 36, and the multi-channel digital signal processor 36 acquires a signal. And tracking to provide a pseudo distance measurement P_ {SV_i A_j} and a carrier phase measurement Φ_ {SV_i A_j} for each antenna from each satellite. In addition, the multi-antenna satellite signal receiver 22 uses one multi-channel digital signal processor 36 instead of several digital signal processors, so that each pseudorange measurement value P_ {SV_i A_j} and a carrier phase measurement value Φ_ {SV_i The effect of equalizing the receiver clock bias included in A_j}) can be obtained.

On the other hand, the measured value error detector 24 shown in FIG. 2 includes a pseudo distance calculator 40 to the center of the vehicle, a pseudo distance error detector 42, and a carrier phase measurement difference calculator 44 as shown in FIG. And a carrier phase measurement error detection unit 46 to determine whether a multipath error is included in the pseudo distance measurement value P_ {SV_i A_j} and the carrier phase measurement value Φ_ {S_i A_j} and infer that the error is included. Omit measurements taken.

Referring to FIG. 4, in the pseudo distance calculation unit 40 to the vehicle center, a pseudo distance measurement value P_ {SV_i A_j} input from the multi-antenna satellite signal receiver 22 and a vehicle input from the navigation calculator 14. Using the azimuth and satellite information (elevation angle and direction angle) of the satellite, the pseudo distance from the satellite to the center of the vehicle is calculated and output for the pseudo distance received at each antenna. At this time, the center of the vehicle can be set arbitrarily.

The pseudorange error detector 42 compares the pseudoranges output from the pseudorange calculator 40 to determine whether an error is included and outputs a set of satellites and antennas {SV_i, A_j} having no errors. The carrier phase measurement difference calculation unit 44 calculates and outputs a difference between the carrier phase measurement values based on information on a set of satellites and antennas {(SV_i, A_j)} having no error. The carrier phase measurement error detection unit 46 detects and removes the error of the carrier phase measurement using the navigation sensor information and the satellite information. Accordingly, the carrier phase measurement error detection unit 46 outputs the pseudo-corrected pseudorange measurement value, the error-corrected carrier phase measurement value, and the error-corrected vehicle speed / angular velocity to the navigation calculation unit 14 to detect the position, speed, and azimuth angle of the vehicle. Used for calculation.

The navigation sensor unit 12 includes a gyro sensor and a speed sensor required for auto navigation of the vehicle, and detects and outputs a rotation angle and a speed of the vehicle being driven. The navigation calculator 14 calculates the current position of the vehicle based on the position information, the speed information, and the azimuth information of the vehicle, which are input from the navigation sensor unit 12 and the measured value error detector 24, and measures the measured error. The cumulative error is corrected to the value input to the detector 24. The controller 16 includes a ROM for storing a program for controlling the overall operation of the vehicle navigation system and a RAM for temporarily storing data processed during the operation. The control unit 16 reads the map information of the surrounding area from the map data storage unit 20 on the basis of the driving information obtained by the navigation calculation unit 14 and displays it on the display unit (not shown). In addition to the above map data, the control unit l6 displays various directions necessary for driving such as displaying the direction of travel of the vehicle, the distance to the destination, the current moving speed of the vehicle, the path set by the driver before driving, and the optimal route to the destination. Provide additional information to the driver. The map data storage unit 20 stores map information and other additional information.

Hereinafter, the detailed operation of the measurement error detector 24 shown in FIG. 4 will be described with reference to FIG. 5 in which a coordinate system and an antenna position are defined.

The center of the vehicle can be arbitrarily selected in the vehicle, and it is assumed that each antenna from the center of the vehicle is located at the same distance d and is in one horizontal plane. It is assumed that the N axis is a horizontal axis facing north from the center of the vehicle and the E axis is a horizontal axis facing east from the center of the vehicle. The N and E axes are generally the same as the local horizontal coordinate system defined in dead reckoning. On the other hand, the X-axis is a horizontal axis from the center of the vehicle toward the bow direction as a reference for determining the heading angle of the vehicle and changes as the vehicle rotates. Ψ is the angle between the N and X axes, which is the azimuth angle of the vehicle, and phi _ i is the angle between the X axis and the axis on which the antenna A_i is placed. Φ i and θ i represent the azimuth and elevation angles from the N-axis to the i-th satellite.

Hereinafter, referring to FIG. 5 described above, the operation of each unit of the measurement error detection unit 24 will be described. First, the pseudo distance calculation unit 40 up to the center of the vehicle;

The pseudo-distance measurement value P_ {SV_i A_j} between the i-th satellite and the antenna A_j is expressed by Equation 1 below.

[Equation 1]

In Equation 1, r_ (SV_j A_j) is the distance between the i-th satellite and the antenna A_j, and c, b_i, T, δ_p, w_p are luminous flux, clock bias of the i-th satellite, clock bias of the receiver, delay error and Receiver noise is shown. f_p is an error included in the measurement value and exists independently of each measurement value.

If r_ (SV_j A_j)) >> d, Equation 2 is established.

[Equation 2]

In Equation 2, r_ (SVi 0) is a distance from the satellite to the vehicle center. Therefore, pseudo range correction value for vehicle center for each P_ (SV_i A_j) By adding, it is possible to calculate the pseudo distance with respect to the vehicle center received from each antenna.

On the other hand, in the pseudo-range error detection unit 42;

By comparing P_ {SV_i 0} ^ j values calculated from several antennas for one satellite, it is possible to detect which pseudorange measurements contain errors. As a comparison method, a statistical method of comparing the variance of the difference of each measurement may be used. However, in general, P_ {SV_i 0} ^ j> 0, and errors such as multipath errors, which frequently occur in urban areas, have the property of delaying signals, so the smallest value among each P_ {SV_i 0} ^ j values A method of calculating a difference from other P_ {SV_i 0} ^ j values and comparing them may also be a method of finding a pseudo distance including an error. In this case, the threshold indicating whether the error is included may be determined according to the magnitude of the measurement lock of the receiver. Therefore, by determining whether each measurement includes an error, a set of satellites and antennas S_p = {(SV_i, A_j)} for a measurement without error can be obtained.

Hereinafter, the operation of the carrier phase measurement difference calculation unit 44 will be described. First, when no error occurs, the carrier phase measurement value φ_ {SV_i A_j} between the i th satellite and the antenna A_j is expressed as in Equation 3 below. do.

[Equation 3]

In Equation 3, r_ {SV_i A_j} is the distance between the i-th satellite and the antenna A_j Each represents the speed of light, the clock bias of the i-th satellite, the clock bias of the receiver, the delay error, the unknown integer between the i-th satellite and antenna A_j and the receiver carrier measurement noise. The difference ^δφ _SVAj with respect to the time of (φ_ {SV_i A_j}) in Equation 3 is obtained as shown in Equation 4 below.

[Equation 4]

If the time interval for finding the difference is small enough, Can be expressed as Equation 5 below.

[Equation 5]

In Equation 5, U_i is a direction cosine vector from the antenna to the satellite, Is a vector representing the change in position of each of the antennas A_j and the i-th satellite. However, if an error such as a multipath error exists, U_i is not the direction cosine vector from the antenna to the satellite, but the direction cosine vector U_MP_i in the direction in which the multipath signal is received from the antenna. Therefore, considering multipath error Can be expressed as in Equation 6 below.

[Equation 6]

And Difference for each antenna Is obtained as shown in Equation 7 below.

[Equation 7]

In Equation 7 Is the position change of the vehicle center as shown in Equation 8 And the change of antenna A_j relative to the vehicle center, i.e. It can be expressed as the sum of.

[Equation 8]

In Equation 8 May be represented by Equation 9 in the NED coordinate system defined based on the center of the vehicle.

[Equation 9]

In addition, U_i may be represented by Equation 10 using the direction angle and elevation angle of the satellite.

[Equation 10]

therefore Is as shown in Equation 11 below.

[Equation 11]

Finally, the operation of the carrier phase measurement error detection unit 46 will be described first. Can be calculated from navigation sensor information provided from the navigation calculator 14, that is, azimuth information of the vehicle and azimuth and elevation angle information of each satellite. For the set of satellites and antennas S_p = {(SV_i, A_j)} output from the pseudorange error detector 42 If the values are expressed as ZETA _PHI, which is a vector, it is expressed as Equation 12 below.

[Equation 12]

And with a navigation sensor like a gy If can be measured in conjunction with ZETA _ PHI can be represented by the following equation (13).

[Equation 13]

In Equation 13, f_g and omega_g are measurement error and noise that may occur in the navigation sensor. Probability verification by constructing a parity vector from the measured value ZETA in Equation 13, or using a similar method It is possible to determine whether the gyro measurement includes an error. Accordingly, except for the measurement values that may be included in the error, a set of satellites and antennas S_p = {(SV_i, A_j)} for the measurement without the multipath error may be obtained. The pseudo-range measurement and the carrier phase measurement corresponding to the set of satellite and antenna S_p = {(SV_i, A_j)} for the measurement without the multipath error are output to the navigation calculator 14 and used for calculating the current position of the vehicle. do. In particular, the pseudo distance measurement is already calibrated to the center of the vehicle, so the calculation time of the current position of the vehicle can be greatly reduced, and the carrier phase measurement can be used to calculate the speed and unknown constant of the vehicle for more accurate azimuth angle of the vehicle. Can be calculated.

As described above, the present invention detects and excludes multipath errors that affect the position, velocity, and azimuth angle calculation of the vehicle from pseudo range measurements and carrier phase measurements, thereby providing more accurate vehicle navigation system in the city where multipath errors are likely to occur. There is an advantage to build. In addition, since the pseudo-range measurement and the carrier phase measurement including the multipath error are excluded from the calculation of the position, velocity, and azimuth of the vehicle, the correction effect of the navigation sensors used in the dead reckoning apparatus can be greatly improved. In addition, since the pseudo distance from the satellite to the center of the vehicle is calculated by calibrating the pseudo distance from each satellite to the antenna, the position of the center of the vehicle can be obtained by one calculation without having to obtain the position of each antenna, thereby reducing unnecessary calculation amount. There is also an effect. In particular, in the error detection of carrier phase measurements, the difference of carrier clothes measured from each satellite can be obtained, thereby reducing the effect of lever arm. Therefore, even if the vehicle rotates about an axis other than the vehicle center assumed Detection is possible.

Claims (3)

In an urban vehicle navigation system using multiple antennas, Receiving satellite signals from GPS (Global Positioning System) satellites through a plurality of antennas to calculate and output a pseudo range measurement value P_ {SV_i A_j} and a carrier phase measurement value Φ_ {SV_i A_j} for each antenna. A multi-antenna satellite signal receiver, Navigation sensor unit for detecting the rotation angle and the speed of the vehicle driving and outputting the navigation sensor information, Input the navigation sensor information, the pseudo distance measurement value P_ {SV_i A_j} and the carrier phase measurement value Φ_ {SV_i A_j} to compare the pseudo distance measurement values calculated from a plurality of antennas for one satellite, and thereby multipath error. A measurement error detection unit for detecting a measurement value including and outputting a pseudorange measurement value and a carrier phase measurement value set other than the measurement value including the multipath error; A navigation calculator configured to receive the output pseudorange measurement value, the carrier phase measurement value set, and the navigation sensor information to calculate and output driving information of the vehicle; Urban vehicle navigation system using a multi-antenna, characterized in that configured as a control unit for reading and displaying the map information of the surrounding area on the basis of the driving information. According to claim 1, The multi-antenna satellite signal receiving unit; RF receivers connected to each of a plurality of antennas to receive satellite signals from each of the satellites, convert the received satellite signals into intermediate frequencies, and perform sampling; Multi-channel that calculates and outputs pseudo distance measurement (P_ {SV_i A_j}) and carrier phase measurement value (Φ_ {SV_i A_j}) for each antenna from each satellite by capturing and tracking satellite signals input through multiple channels. Urban vehicle navigation system using multiple antennas, characterized in that the digital signal processing unit. The apparatus of claim 2, wherein the measurement error detection unit; A distance calculator for calculating and outputting a pseudo distance from each of the satellites to the center of the vehicle using the pseudo distance measurement value P_ {SV_i A_j} of each antenna and the azimuth and satellite information of the vehicle; Comparing the pseudoranges calculated from a plurality of antennas with respect to one satellite output from the distance calculator, it is determined whether to include a multipath error and outputs a set of satellites and antennas (SV_i and A_j) without a multipath error. Pseudo-range error detection unit, The difference with respect to time of the input carrier phase measurement value (Φ_ {SV_i A_j}) Carrier phase measurement difference calculation unit for calculating and outputting The difference with respect to the time of the input azimuth, satellite information, navigation sensor information and the carrier phase measurement value Φ_ {SV_i A_j} ( Urban carrier using multi-antenna characterized in that it comprises a carrier phase measurement error detection unit for determining whether the multi-phase error included in the carrier phase measurement value (Φ_ {SV_i A_j}) and outputs only the measurement value without the multipath error Vehicle navigation system.