KR20190050157A - System and method for precise position estimation using carrier-phase gps - Google Patents

Abstract

According to the present invention, provided is a system for estimating a precise position, which comprises: a first step of estimating an initial position of a mobile station and an unspecified number of carrier wave measurement values using a code measurement value; a second step of setting a search range of the unspecified number; a third step of calculating the amount of positional shift between epoxies using a carrier wave measurement value and storing the amount of positional shift; a fourth step of estimating an unspecified number and calculating a covariance; a fifth step of evaluating an unspecified number candidate in an unspecified number search range; a sixth step of determining an unspecified number; and a seventh step of performing accurate positioning using the determined unspecified number.

Description

TECHNICAL FIELD [0001] The present invention relates to a system and method for precise position estimation using a carrier phase GPS,

The present invention relates to a precise position estimation system and method using a carrier phase GPS, and more particularly to a precise position estimation system and method for precisely estimating a position of a mobile station using a carrier phase GPS.

The so-called Global Positioning System (GPS), a satellite positioning system, is a navigation system built by the US government that allows information to be transmitted from satellites anywhere on the earth such as the ground, Which is composed of three parts, that is, a satellite group, a ground control station, and a user, in order to receive and measure the position of a stopped reference station or a mobile station being moved.

Here, the antenna and the GPS receiver provided in the reference station or the mobile station process the signal received from the phase to calculate the position, velocity and time of the reference station or the mobile station equipped with the GPS receiver, And simultaneously observes the received carrier phase signal. This is because the three-dimensional coordinates and time must be combined to determine four unknowns. In addition, GPS receivers are currently used in various fields such as navigation, position measurement, and time information.

In the early days, GPS was developed for military purposes. However, L1 and C / A codes of the GPS signals are also open to civilians, and the C / A codes broadcasted by GPS satellites enable 24-hour position measurement .

At this time, the GPS satellites are composed of six orbits inclined at about 55 degrees with the equator, four to five satellites are arranged for each orbit, and satellites are placed in the sky of about 20,200 km from the surface of the earth . The idle period of the GPS satellite is 11 hours and 58 minutes, and the GPS satellites rotate the earth two times a day, so that the GPS satellites can always track at least four of the GPS satellites on the earth, The satellite is equipped with a Sethium or Rubidium atomic clock to match the view.

The types of GPS can be divided into various types. The GPS satellite system, that is, the GPS satellite measurements can be divided into a plurality of code measurements having a positional accuracy of several meters, And a carrier measurement value having a positional accuracy of. At this time, since the carrier wave measurement value includes an unknown number, the number of unknown bits should be determined in order to use the carrier wave measurement value.

In addition, using a single satellite navigation system, one GPS receiver capable of receiving four or more GPS satellite signals can obtain the position of the user with a position error of about 30 to 40 m anywhere on the earth, Is basically composed of a GPS receiver provided in the reference station and the reference station, and a mobile station, i.e., a GPS receiver for the user. Since the actual distance (true range) for all visible satellites can be calculated in the reference station, it is possible to use the GPS receiver of the reference station in the reference station installed at the precise geodetic position, The pseudo range error can be calculated from the pseudo range by the pseudo range. If the distance between the reference station and the mobile station is relatively close, since the pseudo range error of the reference station and the pseudo range error of the mobile station are almost the same, if the pseudo range of the mobile station is corrected through the error calculated by the reference station, And the position of the user can be obtained with a position error of 1 ~ 2m level.

Carrier-corrected satellite navigation systems generally have a much higher resolution than the code measurements, so that the locus error can be expected from a few millimeters to a few centimeters. Once the GPS receiver starts tracking the carrier measurements, providing accumulated carrier phase values for a specific time period, and knowing the number of unknowns contained in the carrier measurements, which is the initial number of carrier cycles, The location can be obtained. That is, the carrier-corrected satellite navigation system using the carrier phase must find out the initial unknown number included in the carrier wave measurement, in addition to the user's initial position.

The code measurement value can be expressed by the following equation (1).

---(1)

---(One)

In this case, ρ _i is the pseudorange (m) by the code measurement to the i th satellite, r _i is the geometric distance (m), c is the speed of light, dt _r is the receiver clock error (s), dt _i ^s is the satellite clock error , i _i is the ionospheric delay error (m), T _i is the troposphere delay error (m), d _orb the satellite position error, ζ is Tide (tide) effect (m), υ _ρ is the multipath error, other noise (m ) to be.

The carrier phase measurement value can be expressed by the following equation (2).

---(2)

---(2)

Here, l _i is the i-th pseudo distance (m) by the carrier phase measurements to the satellite, r _i is the geometrical distance (m), c is speed of light, dt _r is the receiver clock error (s), dt _i ^s is the satellite clock error, i _i is the ionospheric delay error (m), T _i is the troposphere delay error (m), d _orb the satellite position error, λ is the carrier wavelength (m), N _i is not assigned number (cycles), υ _l is a multi- Path error, and other noise (m).

There are following methods to correct error factor in GPS measurement.

(1) Satellite clock error

It is caused by the difference between the atomic clock mounted on the satellite and the GPS reference time, and an error of about 3m occurs at the maximum.

To alleviate this, we use reception period difference or receive and use real-time satellite clock correction information provided by IGS, JPL, and so on. In order to reduce the satellite clock error in the stand-alone method using only one receiver, satellite correction information of the Satellite Based Augmentation System (SBAS), which is a satellite-based correction navigation system, is received and corrected. In this case, the residual error in the reception period difference becomes less than cm, and when the IGS, JPL, or SBAS correction information is received, the residual error is reduced to about 3 ns (1 m) maximum.

That is, if the difference between the observed value of the user and the observed value of the reference station is performed, the satellite clock error and the satellite position error can be eliminated.

(2) satellite position error

 The satellite position error is an error caused by the inaccuracy of the satellite broadcast ephemeris. In the ground station that manages the GPS, new satellite orbit information is sent to the satellite about every 2 hours, and the satellite sends this value to the user by including it in the navigation message. However, since the position of the satellite obtained using this orbit information does not coincide with the actual satellite position, the satellite position error occurs at a maximum of about 3 m.

 In order to reduce this, it is necessary to use real-time satellite position correction information provided by IGS, JPL, etc., when the distance between the two receivers is short (10 km or less) In order to reduce the error in the stand-alone method, the satellite position correction information of the SBAS is received and corrected. Using the information of the reception period difference and IGS and JPL, the residual error is reduced to less than cm, and when the SBAS information is received and corrected, the residual error is about 1 m at maximum.

(3) Ionospheric delay error

Nearly 100 km from the ground, ionized air molecules by solar energy exist in the ionosphere, where free electrons are dense. The satellite signal is delayed as the GPS signal passes through the ionosphere. This is called the ionospheric delay effect, and the position error due to the ionospheric delay effect is about 20 ~ 30m in the daytime when the solar activity is active and about 3-6m Error occurs.

As a typical method to reduce this, there is a case where the distance between the two receivers is short (10 km or less), the ionospheric delay error disappears in the reception period difference, and the correction information such as IGS and JPL is received or an ionospheric free method using a multi- have. In order to reduce the ionospheric delay error in the stand-alone method, it is possible to apply the ionospheric-free method and the SBAS ionospheric correction model.

The residual error in the above method is about 3m for SBAS and the remaining method is less than 30cm.

Below is a summary of the Ionospheric-free contents.

When the satellite signal passes through the ionosphere, the ionospheric refractive index differs according to the frequency of the signal. Considering the total number of electrons present in the ionosphere, the ionospheric-free equation can effectively remove the ionospheric delay error. For example, using a multi-frequency receiver such as GPS L1 (1575.42MHz), L2 (1227.6MHz), and L5 (1176.45Mhz) compensates for about 99% of the ionospheric delay error, with a residual error of up to about 30cm.

(4) Tropospheric delay error

There is an error of about 2.5m to 20m due to the delay caused by the air on the ground about 10km above the ground.

It is difficult to correct the tropospheric error by using the dual frequency because the L band frequency region of the GPS signal has the same refractive index in the troposphere.

A method of effectively correcting the tropospheric delay error is to remove the tropospheric delay error when the distance between the two receivers is short (less than 10 km), and receive correction information such as IGS and JPL. The method of reducing the tropospheric delay error in the stand-alone method is calibrated by applying the SBAS tropospheric model. When the correction information such as the reception period difference, IGS, JPL, etc. is received and corrected, the residual error is reduced to cm or less, and the residual error is about 15 cm when corrected using the SBAS information.

(5) receiver clock error

Although satellites contain very precise atomic clocks, typical receivers use inexpensive crystals or TCXOs, so they have receiver clock errors due to inaccuracies in the receiver clock. In order to mitigate this, if the difference between the reference satellite and the observation satellite is differentiated by using the inter-satellite difference method, the receiver clock error, which is a common part, disappears and the receiver clock error can be reduced.

(6) Tide effect

For high-precision positioning, the cause of the minute displacement of the crust should be considered. Among these displacements, the attraction caused by the sun or the moon causes deformation in the shape of the earth. As a result, the specific position of the indicator changes with time in space. The tide effect is called the tide effect, and the tides affecting the position change can be divided into solid earth tide, ocean loading tide, and pole tide.

1) solid-Earth tide

Solid Earth tide is caused by gravitational forces acting between the earth and the sun and moon. It has the greatest influence at the position closest to the sun or the moon. It varies by about 30 cm in the vertical direction and about 5 cm in the horizontal direction . The change of the position of the surface due to the effect of the tide is due to the periodic position change of the sun and the moon, and thus appears periodically. The position change by the solid earth tide can be removed by modeling using the formula provided by the international organization IERS (International Earth Rotation and Reference Systems Service).

2) ocean loading tide

The difference of the tidal tide is generated by the attraction of the sun and the moon, and the position of the indicator changes by the change of the sea water load. Therefore, the impact is relatively large in coastal areas or islands. This is called an ocean loading tide, and it is known that it does not exceed 5cm in the maximum vertical direction and 2cm in the horizontal direction. Due to the fact that Korea is a peninsula area and many islands, it is necessary to appropriately consider the location change due to the influence of ocean loading tide. The position change by ocean loading tide can be removed by modeling using the formula recommended by IERS.

3) pole tide

The position of the Earth pole changes slowly and does not have a specific period. The change in the position of these poles leads to a change in the centrifugal force due to the rotation of the earth, thus changing the gravity value at a certain position. When the gravity value changes, the position changes with the shape change of the earth. The change of the position due to these factors is called the influence by the pole tide, and it can show a maximum of 2.5cm in the vertical direction and 0.7cm in the horizontal direction. The position change by the pole tide can be removed by modeling using the formula provided by IERS.

However, conventionally, there is an inconvenience that it is necessary to wait for a long time stop state in order to obtain a code measurement value and a carrier measurement value by using the GPS receiver of the reference station and the GPS receiver of the mobile station.

According to the invention described in Patent Document 1, a carrier phase accumulation value of satellite signals is acquired once on the mobile station side, and a plurality of carrier satellite accumulation values on the reference station side are acquired by the carrier phase accumulation value And estimates an unknown number included in a carrier satellite accumulated value of signals transmitted from a satellite received by the mobile station.

However, the above-mentioned Patent Document 1 does not provide a solution to the problem that the mobile station must wait for a long period of time to stop the mobile station in order to determine the number of unknowns to be received.

In the invention disclosed in Patent Document 2, although a method of obtaining a movement locus in a moving object by using a carrier phase GPS is proposed, there is a problem that an accurate locus can be obtained but an accurate position can not be obtained.

Patent Document 1: KR 10-0749835 B1 (Registered Date: August 8, 2007) Patent Document 2: KR 10-1409804 B1 (Registered on Apr. 23, 2014)

In the mobile station, precise position measurement can be performed using the code measurement value and the carrier measurement value of the GPS satellite signal.

A system for accurate position estimation according to the present invention is a system comprising a mobile station capable of receiving a signal from a plurality of GPS satellites and GPS satellites and measuring a code measurement and a carrier measurement, the mobile station comprising: Estimating an unspecified number of carrier measurement values, setting a search range of the unspecified number, calculating and storing a position shift amount between ephemerals by a carrier measurement value, estimating an unspecified number, calculating a covariance, The number of unspecified number candidates in the candidate region is determined, the number of unspecified numbers is determined, and the fine positioning is performed using the determined number of unspecified numbers.

The precise position estimation system is a system for estimating a position of a mobile station by using a position of a mobile station to which a signal is to be received, It is possible to guarantee the continuity of the trajectory by estimating the number of unspecified number of real numbers.

The precise position estimation system is a system for estimating a position of a mobile station based on a position obtained by using all the measurements up to the reduced moment when the number of GPS satellites capable of receiving a signal is decreased and a position obtained by a measurement value excluding GPS satellites excluded The difference can be compensated to a position obtained by a measurement value excluding the excluded satellites and then the number of unspecified number of real numbers after the reduction can be estimated to ensure the continuity of the trajectory.

The present invention provides a precise position estimation method using a system including a mobile station capable of receiving a signal from a plurality of GPS satellites and GPS satellites and measuring a code measurement value and a carrier measurement value, A first step of estimating an initial position of the mobile station and an unidentified number of carrier measurement values; A second step of setting a search range of the unknown number; A third step of calculating and storing the amount of positional shift between epoxies using a carrier wave measurement value; A fourth step of estimating an unknown number and calculating a covariance; A fifth step of evaluating an unspecified number candidate in the unspecified number search range; A sixth step of determining an unspecified number; A seventh step of performing accurate positioning using the determined undetermined number; And a control unit.

The precise position estimation method includes the steps of: when a number of GPS satellites capable of receiving a signal in a mobile station increases, a position is obtained by excluding a measured value after the increased moment, and then the position is used to calculate a new measurement value It is possible to guarantee the continuity of the trajectory by estimating the number of unspecified number of real numbers.

The precise position estimation method is a method of estimating a precise position of a mobile station based on a position obtained by using all measured values up to a decreased instant when a number of GPS satellites capable of receiving a signal is decreased and a position obtained by a measurement value excluding the excluded GPS satellites The difference can be compensated to a position obtained by a measurement value excluding the excluded satellites and then the number of unspecified number of real numbers after the reduction can be estimated to ensure the continuity of the trajectory.

In the mobile station, precise position measurement can be performed using the code measurement of the GPS satellite signal and the carrier measurement.

1 is a block diagram of a mobile station according to the present invention;
2 is a flowchart of a method of estimating a precise position according to the present invention

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

1 is an example of the configuration of a mobile station according to the present invention.

1 includes an antenna 10, an RF unit 110, a DSP unit 120, a navigation unit 130, a DR unit 140, a locus calculation unit 150, and an undetermined number calculation unit 160 do.

The antenna 110 receives a GPS satellite signal and transmits the GPS satellite signal of a high frequency (RF) frequency received through an antenna 110 provided in the mobile station through a radio frequency (RF) To an intermediate frequency (IF), thereby obtaining digital information from the GPS satellite signal. The code measurement value and the carrier measurement value can be determined from the digital information through a DSP (Digital Signal Processor) unit 120. The GPS unit 120 can determine the code measurement value and the carrier measurement value using the code measurement value determined by the DSP unit 120, It is possible to estimate the initial position of the mobile station in which the receiver 100 is provided. At this time, the code measurement may use a single epoch, or may use a plurality of epochs in a stationary state of the mobile station. In the case of using a single epoch, the position error of the mobile station is about 10 to 15 m, and in the case of using a plurality of epochs, the position error of about 4 to 6 m can be obtained.

The DR sensor 140 can perform the DR navigation of the mobile station, that is, the speculative navigation, using the travel distance and the angle measurement values. At this time, the angle sensor may be any one selected from a gyro, a geomagnetic sensor, and a differential odometer, and the distance sensor may be any one selected from a car speedometer, odometer, and accelerometer.

When the DR sensor 140 can not perform positioning due to a small number of GPS satellites, the DR sensor 140 may perform a speculative navigation using only the DR sensor.

The trajectory calculation unit 150 calculates the movement trajectory of the mobile station. The trajectory calculation unit 150 calculates the unknown trajectory of the mobile station. The unknown trajectory calculation unit 160 calculates the unknown trajectory.

2 is a flowchart of a method for estimating a precise position according to the present invention.

The precision position estimation method of FIG. 2 includes the following steps.

(1) first step (S10): estimating the initial position of the mobile station and the number of unassigned carrier measurement values using the code measurements

(2) Step 2 (S20): Setting the search range of the unfixed number

(3) Third step (S30): Calculating the position shift amount between epochs by the carrier wave measurement value and storing

(4) Step 4 (S40): Estimate the number of unknowns and calculate the covariance

(5) fifth step (S50): evaluating the unspecified number candidates in the unspecified number search range

(6) Step 6 (S60): Determine the number of unconfirmed steps

(7) seventh step (S70): performing precision positioning using the determined undetermined number

This is explained in detail as follows.

The pseudorange measurement model of the kth satellite, which eliminates the measurement error by the method described in the error factor and correction method in the GPS measurement, can be expressed as shown in the following equation (3).

---(3)

--- (3)

At this _{time, x sv, k, y sv} , k, z sv, k is an ECEF (Earth-Centered-Earth- Fixed) position of the k th satellite in the coordinate system _{vector, x u, y u, z} u is the receiver in the ECEF coordinate system, B _u is a combination of the satellite and receiver clock errors, c is the speed of light (light velocity), and υ _{ρ, k} is other noise such as multipath error.

Equation (3) can be expressed as Equation (4) below.

---(4)

---(4)

시점에서 선형화한다고 하면, 위의 수식 (3)은 다음의 수식 (5), 수식 (6)과 같이 표시할 수 있다.if,

(3) can be expressed by the following equations (5) and (6). &Quot; (5) "

---(5)

--- (5)

---(6)

--- (6)

At this time, if the following expression (7) is defined, the following expression (8) holds.

---(7)

--- (7)

---(8)

---(8)

When the measurements of m satellites are collected from the i-th epoch, the above equation (8) is expressed by a matrix, and the following equation (9) is obtained.

--(9)

- (9)

At this time, when expressed as the following equation (10), the code measurement value is rearranged as shown by the following equation (11), and the carrier phase, that is, the rearranged value is rearranged as shown in equation (12).

---(10)

--- (10)

---(11)

--- (11)

---(12)

--- (12)

Assuming that the satellite with the highest elevation angle is the first satellite in Equation (9), and the distance between the first satellite and the other satellite is differentiated, the following Equation (13) is obtained.

---(13)

--- (13)

Assuming the following equations (14) and (15)

---(14)

--- (14)

---(15)

--- (15)

The above equations (11) and (12) can be summarized as the following equations (16) and (17).

---(16)

--- (16)

---(17)

--- (17)

At this time, δρ _di, δl _di is the difference between code measurements and carrier phase measurements (m-1 by 1), H di is a vector (m-1 by 3) the difference observation matrix, δx _i is the position vector (3 by 1), N _di is the differentiated unknown vector (m-1 by 1), υ _{dρ, i} and υ _{dl, i} is the other noise (m-1 by 1), and λ is the wavelength.

In the first step, an example of estimating the initial position of the mobile station and the number of uncertainties of the carrier measurement using the code measurements is as follows.

The linearized equation of the difference between the code measurement and the carrier phase measurement at the stationary state (assuming an epoch 0) can be expressed as in the following Equation (18) and Equation (19).

---(18)

--- (18)

---(19)

--- (19)

)는 다음의 수식 (20)과 같다.In the above equation (19), the initial position estimated by the least square method (Least Square)

) Is expressed by the following equation (20).

---(20)

--- (20)

Here, P is expressed by the following equation (21).

---(21)

--- (21)

의 공분산은 다음의 수식 (22)와 같다.At this time,

Is given by the following equation (22).

---(22)

--- (22)

)를 추정하면 다음의 수식 (23)과 같은 수식을 얻는다.By substituting the above equation (20) into the equation (19), the initial undetermined number

), The following equation (23) is obtained.

---(23)

--- (23)

)와 초기 미지정수(

)에는 초기 위치오차가 공통적으로 포함되어 있다.The estimated initial position (

) And initial undetermined number (

), The initial position errors are commonly included.

In the second step, an example of setting the search range of the unfixed number is as follows.

)의 공분산은 다음의 수식 (24)와 같이 표시할 수 있다.Unspecified number (

) Can be expressed by the following equation (24).

--- (24)

At this time, the following equation (25) holds,

---(25)

--- (25)

The following equation (26) is established

---(26)

--- (26)

The above equation (24) is summarized as the following equation (27).

---(27)

--- (27)

를 구하는 방법은 다음 수식 (28)과 같다.Where the covariance of the measure at the initial 0 epoch

Is obtained by the following equation (28).

--- (28)

Assuming that the measured value of the first satellite is not correlated with the measured value of the i-th satellite, the above equation (28) is approximated as the following equation (29).

---(29)

--- (29)

도 구할 수 있다.In this way,

Can be obtained.

At this time, if the permissible error range (for example, 1%, 3%, etc.) is set, the allowable number of undefined numbers is determined by using the above expression (27).

In the third step, an example of calculating the position shift amount between epochs by the carrier wave measurement value and storing it is as follows.

In a typical LAMBDA (Least squares Ambiguity Decorrelation Adjustment), the number of undefined numbers is determined by collecting measurements during several tens to several hundred epochs in a stationary state. (16) and (17), δ x _i is fixed to the (3 by 1) matrix. In the moving state, δ x _i (3 * n by 1) when the measured value of n epoch is accumulated. This step calculates precise δ x _i with delta ICP (Integrated Carrier Phase) and compensates for δ x _i accumulated in the moving antibody at the measurement.

Since the wavelength of the code is about 300 m, the wavelength of the carrier is about 19 cm, and the dispersion of the carrier is very small compared to the code. Assuming that the carrier information coming from epoch 1 is a true value, the updated position is the initial position estimate + λ * delta ICP Integrated Carrier Phase).

If we make the formula based on the carrier phase measurement from the epoch 1,

---(30)

--- (30)

는 초기 위치 오차이다. λ*delta ICP 가 이동량이므로,

를 풀어서 이를 참값으로 가정한다. 여기서 δΘ 는 delta ICP 이다.At this time,

Is the initial position error. Since? * delta ICP is the movement amount,

And assumes it as a true value. Where δΘ is delta ICP.

를 업데이트하면서 이동한 위치를 다음의 수식 (31)을 이용하여 추정할 수 있다.like this

Can be estimated using the following equation (31).

---(31)

--- (31)

는 노미널 포인트(nominal point)로 이전 에폭 위치 추정치(i-1 번째 에폭에서의 위치 추정치)이며,

는 현재 에폭 위치 추정치(i 번째 에폭에서의 위치 추정치)이다.here

Is the previous epoch position estimate (the position estimate in the i-th epoch) at the nominal point,

Is the current epoch position estimate (position estimate in the ith epoch).

,

를 계산한 후 저장할 수 있다.In this way

,

Can be calculated and stored.

In the fourth step, an example of estimating the unfixed number and calculating the covariance is as follows.

The measured values in n epochs obtained in the third step are expressed as a matrix and are expressed by the following equation (32).

---(32)

--- (32)

이고, 이것은 참값으로 가정하고, 위 식은 초기 위치 바이어스인

를 공통으로 포함하고 있다.here

, Which is assumed to be a true value,

As shown in FIG.

Since the position of the satellite changes over time and the visible satellite changes, the observation matrix H _i changes.

로 가정한다.As a result, the error of the trajectory is accumulated over time. At the present stage, there is no change of visible satellite,

.

In the above equation (32), the value is rearranged as the unknown term and the unknown term, and is summarized as the following equation (33).

---(33)

--- (33)

(초기 위치오차)는 바이어스(bias)처럼 남아 있는 항이라 상수처럼 취급한다면, 수식 (33)에서 미지수는 좌변에 있는 미지정수 항이고, 우변에 남아있는 나머지 항은 모두 알고 있는 값으로 미지정수를 추정할 수 있다. 이렇게 추정한 미지정수는 실수 미지정수이며, 미지정수의 검색범위인 오차타원 범위는 미지정수의 공분산 행렬과 같으므로 제2 단계에서 구한 방법과 같이 공분산을 구하면 다음의 수식 (34)와 같다In Equation (33) above,

(Initial position error) is treated as a constant such as a bias, the unknown number in equation (33) is the unknown term in the left side, and the remaining terms in the right side are all known values, Can be estimated. Since the estimated number of unspecified numbers is a real number unspecified number, and the error ellipse range, which is the search range of unspecified numbers, is the same as the unconstrained number covariance matrix, the covariance is obtained as in the second step,

---(34)

--- (34)

The above equation (34) is summarized as the following equation (35).

---(35)

--- (35)

의 분산은 에폭이 증가하면서 누적된다. 하지만 위에서 참값으로 가정했으므로 누적되는 분산이 매우 작으므로 무시 가능하다. 또한 변수 간 상관성을 고려하면 다음의 수식 (36)과 같이 근사 가능하다.Where delta ICP

Is accumulated as the epoch increases. However, since we have assumed a true value above, the accumulated variance is very small and negligible. Also, considering the correlation between variables, it can be approximated as the following equation (36).

---(36)

--- (36)

In the fifth step, an example of evaluating the unspecified number candidates in the unspecified number search range is as follows.

If the number of unspecified number of unknowns is determined in the search range of the unspecified number obtained in the fourth step, fine positioning is performed using the determined number of unspecified positions, and if the number of unspecified numbers is not determined, the process returns to the third step, Step 4 and the fourth step are repeated again.

The evaluation function that evaluates the candidates is as follows.

The unspecified number determination method retrieves the solution that satisfies the objective function equation (37) using the real number unspecified number and the covariance information.

---(37)

--- (37)

이므로 이는 실수 영역이고, 은 N_di 는 정수 영역이므로 미지정수의 오차가 위치의 오차보다 상대적으로 크다. Where Q _dl is the covariance matrix of delta _dl ,

Since N _di is an integer region, the error of the unknown number is relatively larger than the error of the position.

When the measurements of n epochs are collected, the position (? x _i ) and the undetermined number (N _di ) that minimize the next objective function expression (38) are searched using the measured values.

---(38)

--- (38)

In the sixth step, an example of determining the unfixed number is as follows.

The value of the equation (34) above to assess whether less than a certain reference value, is greater than the reference value, the first step to repeat the process of claim 5, Step 3, and is less than the reference value, the number of unassigned the N _di at that time Value.

In the seventh step, an example of precise positioning using the determined undetermined number is as follows.

When the unspecified number value (N _di ) is determined, the position (dx _i ) is also determined, and precise position estimation is performed using the values.

When the mobile station moves, the visible satellite may change, the satellite may be momentarily blocked, or a cycle slip may occur due to an impact. It is necessary to detect and compensate for the change of visible satellite and cycle slip.

First, the change of the visible satellite is divided into two cases: a case where the number of visible satellites increases and a case where the measured value is increased and a case where the number of visible satellites decreases is decreased. If the measured value is satellites changed increases or decrease the new observation matrix (H _i) it is different from the previous epoch observation matrix (H _i-1), so when estimating the number of real number not assigned in the new observation matrix bias than the position determined in the previous epoch (bias ) Value becomes large and the continuity of the trajectory is not ensured. The method for solving this problem can be solved by separating into the following two cases.

(1) When the number of visible satellites increases (occurs at t + 1 epoch)

 Estimating the number of unspecified number of new measurements at the t + 1 epoch using this position after finding the position excluding the measurement added at the t + 1 epoch can guarantee the continuity of the trajectory.

(2) when the number of visible satellites is reduced (at t + 1 epoch)

The difference between the position obtained by using all the measurements in the previous epoch t and the position obtained by the measurements obtained by excluding the missing satellites from the t + 1 epoch is compensated to the position obtained by the measurement values excluding the satellites missing from the epoch. The continuity of the trajectory can be guaranteed.

Next, when the cycle slip occurs, the method of detecting the cycle slip can detect the cycle slip by comparing the displacement amount of the ep GPS GPS measurement with the displacement amount calculated by the DR sensor. In case of cycle slip, compensation can be made by using the amount of position change measured by the DR sensor.

10: Antenna
110: RF section
120: DSP section
130: Navigation Department
140: DR section
150: locus calculation section
160:

Claims (6)

A system comprising a mobile station capable of receiving a signal from a plurality of GPS satellites, GPS satellites and measuring a code measurement and a carrier measurement,
The mobile station estimates an initial position of the mobile station and an unspecified number of carrier measurement values using the code measurement, sets a search range of the unspecified number, calculates and stores the position shift amount between the episodes with the carrier measurement value, Estimates a covariance, evaluates unspecified number candidates in an unspecified number search range, determines an unspecified number, and performs accurate positioning using the determined unspecified number.
The method according to claim 1,
If the number of GPS satellites capable of receiving a signal in the mobile station is increased, the position is obtained by excluding the measured value after the increased moment, and then the number of unspecified number of new measurement values after the increased moment is estimated using the position, Wherein the position of the mobile station is secured by the carrier phase GPS.
The method according to claim 1,
If the number of GPS satellites capable of receiving a signal in the mobile station is decreased, the difference between the position obtained by using all the measurements up to the decreased moment and the position obtained by the measurement value excluding the GPS satellites excluded in the decreased moment And estimating the number of unspecified number of real numbers after the compensation to ensure continuity of the trajectory.
A method for precise location estimation using a system including a mobile station capable of receiving a signal from a plurality of GPS satellites and GPS satellites and measuring a code measurement and a carrier measurement,
A first step of estimating an initial position of a mobile station and an unspecified number of carrier measurement values using a code measurement;
A second step of setting a search range of the unknown number;
A third step of calculating and storing the amount of positional shift between epoxies using a carrier wave measurement value;
A fourth step of estimating an unknown number and calculating a covariance;
A fifth step of evaluating an unspecified number candidate in the unspecified number search range;
A sixth step of determining an unspecified number;
A seventh step of performing accurate positioning using the determined undetermined number;
And estimating the position of the mobile station based on the carrier phase GPS.
The method of claim 4,
If the number of GPS satellites capable of receiving a signal in the mobile station is increased, the position is obtained by excluding the measured value after the increased moment, and then the number of unspecified number of new measurement values after the increased moment is estimated using the position, Wherein the position of the mobile station is secured by the carrier phase GPS.
The method of claim 4,
If the number of GPS satellites capable of receiving a signal in the mobile station is decreased, the difference between the position obtained by using all the measurements up to the decreased moment and the position obtained by the measurement value excluding the GPS satellites excluded in the decreased moment And estimating the number of unspecified number of real numbers after the compensation to ensure the continuity of the trajectory.

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