CN101644756B - Linear GPS dynamic locating accuracy verification instrument and verification method thereof - Google Patents

Abstract

The invention provides a linear GPS dynamic locating accuracy verification instrument and a verification method thereof. The method comprises the following steps: utilizing a motor and a transmission device to enable a GPS antenna to move along a fixed linear rail; utilizing a photoelectric detector to record a passing time and an output coordinate of a GPS receiver at the passing time when the GPS antenna passes by a fixed point on the rail; and comparing the coordinate with a preliminarily and accurately marked coordinate of the fixed point to obtain the dynamic locating accuracy of the GPS antenna. The invention has the advantages of simple structure and easy manufacture, ensures the motion accuracy of the GPS antenna by adopting the fixed rail and accurately tracks the position of the GPS antenna by enabling the GPS antenna to pass by and trigger the photoelectric detector at the fixed point on the rail. The fixed point on the rail can be verified preliminarily and accurately to provide a position reference of the GPS antenna in motion. Compared with a method adopted in the prior engineering, the method has high accuracy and good realizability and maneuverability.

Description

Linear GPS dynamic locating accuracy verification instrument and calibration method thereof

Technical field

The present invention relates to mapping and positioning and navigation field, relate in particular to a kind of linear GPS dynamic locating accuracy verification instrument and calibration method thereof that is used to examine and determine the dynamic locating accuracy of GPS (GPS) orientator.

Background technology

Present engineering use and national standard in, generally include two aspects, i.e. static immobilization precision and dynamic locating accuracy for the calibrating of GPS orientator bearing accuracy.The static immobilization precision is the bearing accuracy under gps antenna remains static, it is static that the calibrating of static immobilization precision requires gps antenna, the measurement result of GPS orientator is compared with known coordinate or measurement average, just can try to achieve static precision of exterior coincidence or precision of inner coincidence.Dynamic locating accuracy is the bearing accuracy under gps antenna is kept in motion, owing to the reference point under the motion state is difficult to obtain, so the calibrating of dynamic locating accuracy is comparatively difficult.

At present generally in the engineering adopt more high-precision measuring method that the GPS dynamic accuracy is examined and determine,, but, be difficult to it is carried out effectively and tracking accurately because gps antenna is kept in motion down such as optical theodolite etc.In addition, also there are some GPS verification fields to adopt point of fixity that the GPS dynamic accuracy is examined and determine, such as in GPS (GPS) the measuring technique rules to RTK (real-time carrier phase difference, Real Time Kinematic) the bearing accuracy method of testing, promptly at GPS receiver verification field, when the vehicle GPS receiver notes checking the precision of its real-time dynamic positioning during by known point.This method is applicable to the GPS equipment that bearing accuracy is low, but for the GPS equipment (such as decimeter grade, centimetre-sized) of hi-Fix, because the kinematic accuracy of carrier (automobile) is difficult to control to permissible accuracy, the kinematic error of carrier will seriously influence measurement result.So above-mentioned two kinds of methods are feasible in theory, but the operability on the engineering is very poor.The defective of these two kinds of methods is: the accuracy and the track that is difficult to be met accuracy requirement that can't guarantee the gps antenna motion.

Summary of the invention

In order to solve GPS receiver dynamic locating accuracy verification problem, the object of the present invention is to provide a kind of linear GPS dynamic locating accuracy verification instrument and calibration method thereof, utilize motor and gearing that gps antenna is moved along a fixing straight line path, when gps antenna during by the point of fixity on the track, utilize the output of photoelectric detector record GPS receiver coordinate, compare the dynamic locating accuracy that obtains gps antenna with the point of fixity coordinate of accurately demarcating in advance then.

The present invention is simple in structure, be easy to make.Owing to adopt trapped orbit, so the kinematic accuracy of gps antenna can be guaranteed, and antenna can trigger the photoelectric detector of fixed point, thereby realize the accurate tracking to the gps antenna position during by the point of fixity on the track.Point of fixity on the track can accurately be measured in advance, and the position reference in the antenna movement promptly is provided.The present invention is than the method precision height that adopts in the present engineering, and realizability and operability are good.

To achieve these goals, linear GPS dynamic locating accuracy verification instrument of the present invention, by a fixing rectilinear orbit, utilize motor and gearing to make gps antenna along this orbital motion, when gps antenna during, the moment of utilizing the photoelectric detector record to pass through by the point of fixity on the track, with the GPS receiver coordinate output in this moment with in advance accurately the point of fixity coordinate of demarcation compare the dynamic locating accuracy that obtains gps antenna, wherein

Described rectilinear orbit possesses the adjustment horizontal device, when fixing on the ground, make track remain level, a plurality of check points or a plurality of surveyed area are set on this track in addition, when a plurality of check point is set, each check point place respectively is provided with a photoelectric detector, when a plurality of surveyed area is set, the a plurality of photoelectric detectors of spaced set in each zone, the spacing of each photoelectric detector is made as the precision that will examine and determine, and the length of surveyed area is L=v * Δ t, wherein, v is the movement velocity of mobile platform, and Δ t is the time interval of GPS location output;

Place a mobile platform on described track, this mobile platform slides along described track, and described gps antenna also is installed on this mobile platform;

Be mounted with motor on described track side,, mobile platform moved from an end of track to the other end by belt or chain drive;

At the other pen recorder that is equipped with of described track, link to each other with GPS receiver and photoelectric detector, the locator data of record GPS receiver output, when described mobile platform passes through each check point or surveyed area, trigger described photoelectric detector output electric pulse and give described pen recorder, comprise the AD sampling apparatus in the pen recorder, be used to write down the correct time of mobile platform by each check point or surveyed area, system was handled when this pen recorder carried out with the GPS receiver before test;

In the motion process, described pen recorder is all noted the position output of GPS receiver, after enough according to the test request collection counting, by computing machine experimental data is handled, can from the position output of GPS receiver, find the time of a certain check point of process according to the time point of record, the locator data of collection and the coordinate of check point are compared, analyze its precision, be provided with under the situation of a plurality of surveyed areas, if gps antenna during by surveyed area the moment of output coordinate be T, the output locator data is (x, y, z), and I photoelectric detector arranged in the surveyed area, the moment by i photoelectric detector in the record is t _i, search immediate t with T _i, and with this point coordinate as reference point coordinate Calculation bearing accuracy.

In addition, the length of described rectilinear orbit should satisfy following relation:

L≥N·10δ+v ²/a

Wherein, the check point number of N for needing, v is the movement velocity of mobile platform, δ is for needing the bearing accuracy of calibrating, the acceleration that a can provide for motor.

In addition, the linear GPS dynamic locating accuracy verification method is the using method of described linear GPS dynamic locating accuracy verification instrument, specifically may further comprise the steps:

1) after preparing to begin test, system processing when at first pen recorder and GPS receiver being carried out;

2) gps antenna is installed on the mobile platform, and guarantees to install firmly;

3) starter motor makes mobile platform according to predetermined speed to-and-fro movement on slide rail by the gearing drive, writes down locator data simultaneously;

4) when mobile platform passes through check point, trigger photoelectric detector and export an electric pulse, the record time at this moment to pen recorder; Be provided with under the situation of a plurality of check points, if the check point of setting has N, mobile platform will form a time series T by the time of i check point _i, if mobile platform passes through i check point, then T J time altogether _iComprise J time point; Be provided with under the situation of a plurality of surveyed areas, if gps antenna during by surveyed area the moment of output coordinate be T, the output locator data is that (x, y z), and have I photoelectric detector in the surveyed area, the moment by i photoelectric detector in the record is t _i, search immediate t with T _i, and with this point coordinate as reference point coordinate Calculation bearing accuracy;

5) finish test, carry out data processing, by the check point time of the passing through locator data of inquiring about this moment of record, compute location precision, check point and GPS receiver are compared with rectangular coordinate under the same coordinate system system, obtain bearing accuracy at measurement point by the multiple spot statistical computation.

The precision of using the present invention to carry out the GPS calibrating depends on: 1) mobile platform kinematic accuracy in orbit; 2) response time of photoelectric detector and to the AD sampling precision of the electric pulse of photoelectric detector output.

Usually mobile platform kinematic accuracy in orbit can be controlled under millimeter level even the millimeter level, far above the bearing accuracy of GPS equipment, so can guarantee the accurate movement track; The response time of photoelectric detector and AD sampling precision can guarantee the time precision of 1 millisecond even microsecond level, the data output frequency of GPS equipment is generally tens hertz at present simultaneously, the time interval that is per two secondary data output is more than 10 milliseconds, that is to say for gps antenna and pass through the data output frequency of the time-sampling precision of check point far above GPS equipment, that is to say that the source of positioning error mainly is a GPS equipment itself.

The invention has the advantages that:

Solved the problem of gps antenna kinematic accuracy by fixing tracks, the error that measures so mainly comes from GPS equipment itself; Can obtain reference point under the motion state by fixedly tracks and photoelectric detection function.Can measure the dynamic locating accuracy of GPS equipment, also can measure simultaneously, can be used in the function calibrating of GPS equipment the static immobilization precision; The measuring accuracy height can satisfy the demand that the GPS equipment of centimetre-sized precision is examined and determine.

Description of drawings

Fig. 1 is that linear GPS dynamic locating accuracy verification instrument of the present invention is formed structural representation;

Fig. 2 is the course of work synoptic diagram of linear GPS dynamic locating accuracy verification instrument of the present invention;

Fig. 3 is the position view of check point among the linear GPS dynamic locating accuracy verification instrument embodiment of the present invention;

Fig. 4 is the working method synoptic diagram of photoelectric detector among the linear GPS dynamic locating accuracy verification instrument embodiment of the present invention;

Fig. 5 is the workflow diagram of linear GPS dynamic locating accuracy verification method of the present invention.

Reference numeral

1 track, 2 mobile platforms, 3 antennas

4 motors, 5 gearings, 6 pen recorders

7 photoelectric detectors, 18 photoelectric detectors, 29 photoelectric detectors 3

The light-receiving device of the light projector 7-2 photoelectric detector of 7-1 photoelectric detector

Embodiment

Below in conjunction with the drawings and specific embodiments linear GPS dynamic locating accuracy verification instrument of the present invention and calibration method thereof are described further.

Fig. 1 is that linear GPS dynamic locating accuracy verification instrument of the present invention is formed structural representation, and Fig. 2 is the course of work synoptic diagram of linear GPS dynamic locating accuracy verification instrument of the present invention.As illustrated in fig. 1 and 2, linear GPS dynamic locating accuracy verification instrument of the present invention comprises: a smooth linear pattern track 1, this track 1 possesses the adjustment horizontal device, when fixing on the ground, make track 1 remain level, on this track check point is set in addition, the quantity of check point can be adjusted as required.Do not wait from one to several, but the spacing of two check points should be greater than the precision that will examine and determine.The linearity of the track between two check points is less than the dynamic locating accuracy of tested GPS receiver, and track length should satisfy calibrating needs L 〉=N10 δ+v ²/ a, the track two ends have snubber assembly; Place a mobile platform 2 on described track, this mobile platform 2 slides along described track 1, unlikelyly in slip falls down from track 1, in addition, gps antenna 3 is installed on described mobile platform 2; As telecontrol equipment, at the other motor 4 of settling of described track, motor 4 makes mobile platform 2 move to the other end from an end of track 1 by belt or chain drive; It is other that one cover pen recorder 6 is installed on track 1, link to each other with GPS receiver and photoelectric detector, the locator data of record GPS receiver output, comprise the AD sampling apparatus in the pen recorder 6, be used to write down the correct time of mobile platform 2 by each check point, system was handled when this pen recorder 6 carried out with the GPS receiver before test; At each check point place one photoelectric detector is set, when mobile platform passes through this check point, triggers photoelectric detector, export an electric pulse and give pen recorder 6, the record time at this moment, in the motion process, pen recorder 6 is all noted the position output of GPS receiver.

The work that linear GPS dynamic locating accuracy verification instrument of the present invention will be finished is on the basis of a trapped orbit dynamic locating accuracy of GPS receiver to be examined and determine, therefore, in the present embodiment, dynamic accuracy calibrating with meter accuracy GPS receiver is an example, with reference to figure 1 and Fig. 2, the course of work of calibrating instrument is described.

The user at first needs to design the length of calibrating instrument track 1, and the number and the position thereof of the check point that is provided with on track 1.The number and the spacing of the bearing accuracy of the length of described track 1 and GPS receiver, required movement velocity, acceleration that gearing can provide and check point are relevant.For example, Fig. 3 is the position view of check point among the linear GPS dynamic locating accuracy verification instrument embodiment of the present invention.As shown in Figure 3, for the GPS receiver of meter accuracy, if need 4 check points, needing the precision of calibrating is 1 meter, and needing the speed of calibrating is 5m/s, and the acceleration that motor provides is 2m/s ², then can design track length is greater than 52.5 meters, 10 meters of check point spacings.Be to guarantee the continuity of motion, track 1 two ends have snubber assembly, make mobile platform 2 unlikely tracks that skid off on the track.

If wanting calibration accuracy is the GPS receiver of 0.1m, need 5 check points, needing the speed of calibrating is 5m/s, the acceleration that motor provides is 2m/s ², then designing track length can be greater than 17.5 meter, 1 meter of check point spacing.

Fig. 4 is the working method synoptic diagram of photoelectric detector among the linear GPS dynamic locating accuracy verification instrument embodiment of the present invention, as shown in Figure 4, at the check point place photoelectric detector 1～3 is set, photoelectric detector 1～3 adopts correlation, promptly, the light projector 7-1 of photoelectric detector and the light-receiving device 7-2 of photoelectric detector adopt the correlation mode to install, and its manner of execution can be made as dark moving, i.e. shading action.That is to say that when mobile platform 2 passed through the optical axis of each photoelectric detector 1～3 successively, photoelectric detector 1～3 moved, the output high level.

In addition, Fig. 5 is the workflow diagram of linear GPS dynamic locating accuracy verification method of the present invention.Below with reference to this process flow diagram linear GPS dynamic locating accuracy verification method of the present invention is described in detail.

As shown in Figure 5, linear GPS dynamic locating accuracy verification method of the present invention is the using method of above-mentioned linear GPS dynamic locating accuracy verification instrument, may further comprise the steps:

1) after preparing to begin test, system is handled when at first pen recorder 6 and GPS receiver being carried out;

2) gps antenna 3 is installed on the mobile platform 2, and guarantees to install firmly;

3) start telecontrol equipment (for example, motor 4 and gearing 5), make mobile platform 2, write down locator data simultaneously according to predetermined speed to-and-fro movement on track 1;

When 4) mobile platform 2 is by each check point, trigger photoelectric detector (for example, photoelectric detector 1～3), export an electric pulse and give pen recorder 6, the record time at this moment; If the check point of setting has N, mobile platform 2 will form a time series T by the time of i check point _i, if mobile platform passes through i check point, then T J time altogether _iShould comprise J time point.

5) finish test and carry out data processing, the locator data of inquiring about this moment by the check point time of passing through of record, compute location precision.

Precision calculation is with comparing with rectangular coordinate under the same coordinate system system detecting with the GPS receiver, by calculating the bearing accuracy at measurement point.

If the time series by i check point is T _i, the j time time point by this check point is t _Ij, be (x according to this time point inquiry locator data _Ij, y _Ij, z _Ij);

The coordinate of i the check point of measuring before detecting is (X _i, Y _i, Z _i);

Then the precision of each coordinate components is:

${\mathrm{\δ}}_x=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\underset{j=1}{\overset{J}{\mathrm{\Σ}}}\sqrt{{(x_{\mathrm{ij}}-X_i)}^2}/\mathrm{NJ}$

${\mathrm{\δ}}_y=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\underset{j=1}{\overset{J}{\mathrm{\Σ}}}\sqrt{{(y_{\mathrm{ij}}-Y_i)}^2}/\mathrm{NJ}$

${\mathrm{\δ}}_z=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\underset{j=1}{\overset{J}{\mathrm{\Σ}}}\sqrt{{(z_{\mathrm{ij}}-Z_i)}^2}/\mathrm{NJ}$

Detected GPS receiver bearing accuracy is:

$\mathrm{\&delta;}=\sqrt{{\mathrm{\&delta;}}_x^2+{\mathrm{\&delta;}}_{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="H2008102475739E00011.png,H2008102475739E00021.png"\; state="\{\{state\}\}">y</figure-callout>}}^2+{\mathrm{\&delta;}}_{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="H2008102475739E00011.png,H2008102475739E00021.png"\; state="\{\{state\}\}">z</figure-callout>}}^2}$

The manufacturer that has at present provides GPS receiver bearing accuracy respectively according to plane positioning precision and elevation location precision, and then the plane positioning precision is

$\mathrm{\&delta;}=\sqrt{{\mathrm{\&delta;}}_x^2+{\mathrm{\&delta;}}_{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="H2008102475739E00011.png,H2008102475739E00021.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}$

N, J can be specified by the speed that detects as required, bearing accuracy and GPS output frequency in above-mentioned each parameter.

In above-mentioned example, suppose that the detection speed that needs is v, needing the bearing accuracy of calibrating is δ, the time interval (inverse of output frequency) of location output is Δ t, generally can require:

v≤δ/Δt

That is to say that wanting calibration accuracy is the instrument of 1m, output frequency is 10Hz, and the speed maximum can reach 10m/s during calibrating; And want calibration accuracy is the instrument of 0.1m, and output frequency is 25Hz, and the speed maximum can reach 2.5m/s during calibrating.

Because GPS exports the result according to certain frequency, so should obtain by interpolation at the coordinate at check point place.

It more than is the explanation of the idiographic flow when linear GPS dynamic locating accuracy verification method of the present invention is realized in one embodiment, the check point place is provided with a cover photoelectric detector in this embodiment, so the speed for platform has certain limitation among this embodiment.When practical application, except the cited method of the foregoing description, can also carry out following improvement: with the conceptual expansion of check point is one section zone on the track, the some photoelectric detectors of spaced set in this zone.The length of surveyed area is L=v * Δ t, and the spacing of photoelectric detector can be made as the precision that will examine and determine.For example, calibrating speed is 10m/s, and output frequency is 25Hz, and then the length of surveyed area is 0.4m, and the precision that examine and determine is 0.1m, then can adopt 4 photoelectric detectors, spacing 0.1m.In this embodiment if gps antenna during by surveyed area the moment of output coordinate be T, the output locator data is that (x, y z), and have I photoelectric detector in the surveyed area, the moment by i photoelectric detector in the record is t _i, search immediate t with T _i, and with this point coordinate as reference point coordinate Calculation bearing accuracy.

Claims (7)

1. linear GPS dynamic locating accuracy verification instrument, it is characterized in that, by a fixing rectilinear orbit, utilize motor and gearing to make gps antenna along this orbital motion, when gps antenna during, the moment of utilizing the photoelectric detector record to pass through by the fixed test point on the track, with the GPS receiver coordinate output in this moment with in advance accurately the fixed test point coordinate of demarcation compare the dynamic locating accuracy that obtains gps antenna, wherein

Described rectilinear orbit possesses the adjustment horizontal device, when fixing on the ground, make track remain level, a plurality of check points or a plurality of surveyed area are set on this track in addition, when a plurality of check point is set, each check point place respectively is provided with a photoelectric detector, when a plurality of surveyed area is set, the a plurality of photoelectric detectors of spaced set in each zone, the spacing of each photoelectric detector is made as the precision that will examine and determine, and the length of surveyed area is L=v * Δ t, wherein, v is the movement velocity of mobile platform, and Δ t is the time interval of GPS location output;

Place a mobile platform on described track, this mobile platform slides along described track, and described gps antenna also is installed on this mobile platform;

Be mounted with motor on described track side,, mobile platform moved from an end of track to the other end by belt or chain drive;

At the other pen recorder that is equipped with of described track, link to each other with GPS receiver and photoelectric detector, the locator data of record GPS receiver output, when described mobile platform passes through each check point or surveyed area, trigger described photoelectric detector output electric pulse and give described pen recorder, comprise the AD sampling apparatus in the pen recorder, be used to write down the correct time of described mobile platform by each check point or surveyed area, system was handled when this pen recorder carried out with the GPS receiver before test;

In the motion process, described pen recorder is all noted the position output of GPS receiver, after enough according to the test request collection counting, by computing machine experimental data is handled, can from the position output of GPS receiver, find the time of a certain check point of process according to the time point of record, the locator data of collection and the coordinate of check point are compared, analyze its precision, be provided with under the situation of a plurality of surveyed areas, if gps antenna during by surveyed area the moment of output coordinate be T, the output locator data is (x, y, z), and I photoelectric detector arranged in the surveyed area, the moment by i photoelectric detector in the record is t _i, search immediate t with T _i, and with this point coordinate as reference point coordinate Calculation bearing accuracy.

2. linear GPS dynamic locating accuracy verification instrument as claimed in claim 1 is characterized in that, at the two ends of described rectilinear orbit snubber assembly is installed also.

3. linear GPS dynamic locating accuracy verification instrument as claimed in claim 1 is characterized in that, the linearity of the track between any two check points that are provided with on the described rectilinear orbit is less than the dynamic locating accuracy of tested GPS receiver.

4. linear GPS dynamic locating accuracy verification instrument as claimed in claim 1 is characterized in that, described rectilinear orbit length satisfies following formula:

L≥N·10δ+v ²/a

Wherein, N is the check point that needs or the number of surveyed area, and v is the movement velocity of described mobile platform, and δ is for needing the bearing accuracy of calibrating, the acceleration that a can provide for motor.

5. a linear GPS dynamic locating accuracy verification method is the using method of the described linear GPS dynamic locating accuracy verification instrument of claim 1, specifically may further comprise the steps:

1) after preparing to begin test, system processing when at first pen recorder and GPS receiver being carried out;

2) gps antenna is installed on the mobile platform, and guarantees to install firmly;

3) starter motor makes mobile platform according to predetermined speed to-and-fro movement on slide rail by the gearing drive, writes down locator data simultaneously;

4) when mobile platform passes through check point, trigger photoelectric detector, export an electric pulse and give pen recorder, the record time at this moment; Be provided with under the situation of a plurality of check points, if the check point of setting has N, mobile platform will form a time series T by the time of i check point _i, if mobile platform passes through i check point, then T J time altogether _iComprise J time point; Be provided with under the situation of a plurality of surveyed areas, if gps antenna during by surveyed area the moment of output coordinate be T, the output locator data is that (x, y z), and have I photoelectric detector in the surveyed area, the moment by i photoelectric detector in the record is t _i, search immediate t with T _i, and with this point coordinate as reference point coordinate Calculation bearing accuracy;

5) finish test and carry out data processing, the check point time of the passing through locator data of inquiring about this moment by record, the compute location precision compares check point and GPS receiver with rectangular coordinate under the same coordinate system system, obtain bearing accuracy at measurement point by the multiple spot statistical computation.

6. linear GPS dynamic locating accuracy verification method as claimed in claim 5 is characterized in that, if the time series of setting by i check point is T _i, the j time time point by this check point is t _Ij, be (x according to this time point inquiry locator data _Ij, y _Ij, z _Ij),

The coordinate of i the check point of measuring before detecting is (X _i, Y _i, Z _i);

Then the precision of each coordinate components is:

${\mathrm{\&delta;}}_x=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}\sqrt{{(x_{\mathrm{ij}}-X_i)}^2}/\mathrm{NJ}$

${\mathrm{\&delta;}}_y=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}\sqrt{{(y_{\mathrm{ij}}-Y_i)}^2}/\mathrm{NJ}$

${\mathrm{\&delta;}}_z=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}\sqrt{{(z_{\mathrm{ij}}-Z_i)}^2}/\mathrm{NJ}$

Detected GPS receiver bearing accuracy is:

$\mathrm{\&delta;}=\sqrt{{\mathrm{\&delta;}}_x^2+{\mathrm{\&delta;}}_y^2+{\mathrm{\&delta;}}_z^2}.$

7. linear GPS dynamic locating accuracy verification method as claimed in claim 6 is characterized in that,

Described parameter N, J according to detect needs count or the time is determined, detecting counts is then to satisfy NJ 〉=M by M if require; If be S the detection time that requires, then satisfy JL 〉=Sv;

The movement velocity of described mobile platform satisfies during detection: v≤δ/Δ t, and wherein, δ is for needing the described bearing accuracy of calibrating, and Δ t is the time interval of GPS location output.

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