CN1928585A - Method for improving poisoning precision in space poisoning system - Google Patents

Abstract

The disclosed method for improving position precision in space comprises: building space motion model for object carried space positioning device and sampling device to simulate object motion in update period time scale; combining the sampling data and space coordinate as 'space coordinate-sampling time-sampling parameter' element and the ordered set; in the set, building subset with the space coordinate as reference; extracting the space coordinate from every subset and the initial sampling time to obtain the 'space coordinate-sampling time' element and form set; recalculating the space coordinate for every sampling time. This invention improves positioning precision with less cost.

Description

Improve the method for bearing accuracy in the space positioning system

Technical field

The present invention relates to a kind of space orientation disposal route, relate in particular to the method that improves spatial positioning accuracy in a kind of GPS (GPS, GlobalPositioning System).

Background technology

Space orientation technique is widely used in a plurality of fields.GPS is the most ripe at present positioning system.The typical case of space orientation technique uses and comprises navigator fix and spatial parameter collection location.

When being applied to the data acquisition location, space orientation equipment (as the GPS receiver) collaborative parameters sample devices moves in physical space, by sample devices parameters of interest is sampled.The volume coordinate of parameter sampling value and each sampled point correspondence and sampling instant value go on record, and form sample record.Under many circumstances, the parameter sampling frequency is higher than the effective renewal frequency of volume coordinate of (even far above) space orientation equipment.For example, the general per second of GPS receiver commonly used upgrades 1 volume coordinate information, and in 1 second time, parameter sampling equipment may be at the suitable segment distance of spatial movement and finished parameter sampling repeatedly.So just cause all sample records of before new coordinate information arrives, being obtained, though they in fact (in some way) be distributed in the sampling mobile route on, but all composed the volume coordinate with last acquisition, these data points of also promptly noting have all gathered on the same locus.This phenomenon is referred to as the space clustering effect.The space clustering effect is the sign that there is shortcoming in the spatial positioning accuracy of sample record.When volume coordinate as the important attribute of sample record the time, the space clustering effect is the spatial resolution of limited samples record seriously, thereby has influence on the validity and the serviceability of sample record.

The conventional method that weakens the space clustering effect is to adopt the space orientation equipment with higher coordinate renewal frequency.Be not less than parameter sampling speed if can guarantee the sampling rate of space orientation equipment, the space clustering effect can effectively be eliminated.But the method for this HardwareUpgring has two big weakness.At first, adopt the space orientation equipment with higher coordinate renewal frequency need carry out hardware investment, this will increase financial cost widely.In addition, if parameter sampling speed is very high, what for to obtaining space orientation equipment from current market with corresponding volume coordinate renewal frequency.

Summary of the invention

At the existing problem and shortage of above-mentioned existing space positioning equipment (especially GPS positioning equipment), the purpose of this invention is to provide a kind of by effective elimination space clustering effect improve spatial positioning accuracy cheaply, the advantages of simplicity and high efficiency method.

The present invention is achieved in that the method that improves spatial positioning accuracy in a kind of space positioning system, space orientation equipment and parameter sampling equipment place in the moving object to be positioned, the renewal frequency of parameter sampling equipment specifically may further comprise the steps greater than the volume coordinate renewal frequency of described space orientation equipment:

(1) sets up the spatial movement model for the moving object that is loaded with space orientation equipment and sample devices, with the motion state of this moving object of correct description on positioning equipment coordinate update cycle time scale;

(2) parameter sampling equipment carries out parameter sampling by the frequency of setting, volume coordinate with sampled data and described space orientation measuring apparatus is combined as " volume coordinate-sampling instant-sampling parameter " element, and form " volume coordinate-sampling instant-sampling parameter " set, this set is orderly about " sampling instant "; In this set, be as the criterion with volume coordinate and set up subclass, promptly the continuous group element that volume coordinate is identical constitutes a subclass; Extract the initial sampling instant of the pairing volume coordinate of each subclass and this subclass, obtain " volume coordinate-sampling instant " element and constitute " volume coordinate-sampling instant " set with this element;

(3) value in basis " volume coordinate-sampling instant " set is to sequence, and the spatial movement model that is adopted, again extrapolate in " volume coordinate-sampling instant-sampling parameter " set, the pairing volume coordinate of each sampling instant is upgraded the former volume coordinate that writes down.

(4) if be loaded with the constraint condition of the moving object foundation of space orientation equipment and sample devices about space scope and movement velocity (all-order derivative that also comprises the acceleration uniform velocity); can detect space orientation data exception or error situation in (3) step; and it is suitably handled, with further raising spatial positioning accuracy.

The present invention describes the movement locus of position to be determined object by the spatial movement model is set, and according to the volume coordinate and the sampling instant information of sample record, recomputate the volume coordinate of all records that the space clustering effect takes place, thereby eliminate the space clustering effect effectively, statistically improved setting accuracy.Spatial movement model of the present invention is the mathematical model of characterising parameter sample devices spatial movement pattern, and its input parameter is to extract " volume coordinate-sampling instant " value from the crude sampling record to sequence, can to during the moment output region coordinate of any appointment.This model needn't be described the mass motion pattern in the sampling motion process, and only describes per two typical modules of upgrading the local motion between the volume coordinate, can simulate the actual motion pattern preferably, realizes pinpoint effect.

The present invention does not need to increase hardware cost can realize pinpoint effect, and compares with precision equipment, has saved cost.The present invention carried out precision correction aftertreatment after both being applicable to parameter sampling, also was applicable to real time processing system.

Description of drawings

Fig. 1 is a processing flow chart of the present invention.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing.

At first the relative set to parameter acquisition describes." volume coordinate-sampling instant-sampling parameter " set that sample devices is gathered is designated as C ≡ { r ₁, r ₂..., r _n..., r _N, wherein, r _n(n=1,2 .. is the element of preface with time for what gather C N), r _nInclude volume coordinate attribute p, sampling instant attribute t, and other attribute g (as the sampled value of parameter itself), r _n≡ (p, t, g).

If there is one group of continuous and sample record that have the same space coordinate attributes of order in former set C, then can judge the existence of the buildup effect of having living space, such group element is formed a subclass.For unified mark and processing set C, be that standard is divided whole set with the volume coordinate attribute, like this, the record in the subclass is counted minimum value and is allowed for 1 (when no space clustering effect takes place).Each subclass among the C is designated as:

$C_m=\{r_{m,1},r_{m,2},...,r_{m,N_m}\}$

$=\{(p_m,t_{m,1},g_{m,1})(p_m,t_{m,2},g_{m,2}),...,(p_m,t_{m,N_m},g_{m,N_m})\}$

T wherein _{M, 1}, t _{M, 2}..., t _{M, Nm}Be subclass C _mIn respectively the sample time attribute of element.And C is arranged _m≡ { C ₁, C ₂..., C _m..., C _M.Because the sample record sum is fixed, therefore have $N=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{N}_m.$ Obviously, M≤N sets up necessarily that (equal sign is only in particular cases just set up a kind of, i.e. C _mElement number is 1, the situation that does not promptly have the space clustering effect to take place).

The space orientation average error represents that with δ it is meant the average positioning error of single sample record, is made up of two parts, i.e. the intrinsic average positioning error δ of space orientation equipment ₀, and because the average error 0.5 * (v/f due to the space clustering effect _Update), δ=δ is promptly arranged ₀+ 0.5 * (v/f _Update).Wherein, the intrinsic average positioning error δ of space orientation equipment ₀Be independently a constant or a variable, with volume coordinate renewal frequency and parameter sampling frequency-independent.V is the average translational speed of sample devices, in other words average moving distance in the unit interval; f _UpdateBe the coordinate renewal frequency of space orientation equipment, or perhaps interior space orientation equipment of unit interval is to the update times of volume coordinate.

The space clustering effect promptly refers to subclass C _mIn all sample records have identical coordinate attributes p _m, this is because the coordinate renewal frequency f of space orientation equipment _UpdateWith respect to the parameter sampling frequency f _SampleFiniteness cause (work as f _Update＜f _SampleThe time).Subclass C _mUnified coordinate attributes the continuous motion track that is carved into sample devices between the finish time when initial obviously can not correctly be described by this subclass.Reduce this because of f _UpdateThe sample record space orientation error that causes of finiteness, can reduce by introducing the spatial movement model.By δ=δ ₀+ 0.5 * (v/f _Update) as can be known, if coordinate renewal frequency f _UpdateBe tending towards infinitely great, the v/f of space orientation average error _UpdateItem will be tending towards 0.Existing method can only to a certain degree improve f by adopting more advanced space orientation equipment _UpdateBut this need increase the hardware cost input, and also is merely able to f _UpdateBring up to a limited value, this obviously is difficult to reach technically.

The present invention overcomes above-mentioned deficiency by introducing the spatial movement model just.After introducing the spatial movement model, space orientation average error δ of the present invention can be expressed as:

δ′＝ δ ₀+ δ _model+0.5×( v/f _update′)

Wherein, δ _ModelIt is the average error item that depends on the spatial movement model accuracy.After introducing the spatial movement model, be can calculate to obtain any locus constantly, so location update frequencies f _Update' be equivalent to infinity, promptly ${\stackrel{\‾}{\mathrm{\δ}}}^{\′}={\stackrel{\‾}{\mathrm{\δ}}}_0+{\stackrel{\‾}{\mathrm{\δ}}}_{\mathrm{mode}l}+0.5\×{(\stackrel{\‾}{v}/f_{\mathrm{update}}^{\′})}_{f_{\mathrm{update}}^{\′}\→\∞}={\stackrel{\‾}{\mathrm{\δ}}}_0+{\stackrel{\‾}{\mathrm{\δ}}}_0^{\′}.$

Spatial movement model of the present invention should accord with actual conditions on statistics, in view of the above model extrapolate twice coordinate upgrade between (as from subclass C _mPosition p _mTo C _M+1Position p _M+1) space distribution of all sample records, the state of aggregation that compares to raw readings more is bordering on reality, thus can be on statistics the room for improvement locating accuracy.

After introducing the spatial movement model, space orientation average error δ ' has eliminated the dependence for the coordinate renewal frequency of space orientation equipment, but has newly introduced the error term δ that depends on sampling motion model accuracy _ModelBut as long as sampling motion model and actual state are enough approaching, error term δ ₀' just can be enough little.Promptly as long as δ _Model＜0.5 * (v/f _Update), can reach the improved effect of spatial positioning accuracy.Can prove that the condition that this inequality is set up is δ _Model＜α * [0.5 * (d/ N)].Wherein α is the parameter sampling frequency f _SampleActive position renewal rate f with space orientation equipment _UpdateRatio, i.e. α=f _Sample/ f _Update(the present invention only considers the situation of α＞1).Each subclass C _mBe total to N by one group _m(N _m〉=1) individual element is formed, and note N is C _mThe mean value of element number in the subclass.In mobile sampling process, the mean distance of the position renewal of adjacent subset is designated as d.D/ N represents the average headway of neighbouring sample point.For reaching the purpose of improving spatial positioning accuracy, the spatial movement model formula δ that should satisfy condition _Model＜α * [0.5 * (d/ N)].Its physical significance is that on the meaning of statistical average, the average error of spatial movement model must be less than α times of neighbouring sample average headway.

Should be used for describing in detail flow process of the present invention with vehicle GPS ground positioning equipment.In this case, space orientation equipment is the GPS receiver.Automobile is in motion process, and GPS receiver periodically (being the update cycle with about 1 second usually) upgrades current position coordinates, and other parameter sampling equipment then carries out parameter acquisition with higher sample frequency (for example per second tens more than the sampling).The parameter of being gathered, the GPS position coordinates together with the last time obtains is recorded in the corresponding document.Between per twice renewal of GPS position coordinates, parameter sampling has taken place repeatedly, therefore, record record data in the file, tangible space clustering effect has taken place, can use the present invention and improve bearing accuracy.

In the volume coordinate update cycle (about 1 second) of GPS receiver, can think under most of situation that automobile carries out linear uniform motion; Situation is seldom being done speed change or curvilinear motion; The variation of its movement velocity should be continuous, and meets dull multistage speed substantially.

Describe the spatial movement model of moving object in such cases, be " n rank rate pattern " at adjacent coordinates moving situation in the update cycle.This spatial movement model meets the following conditions: per two adjacent space coordinate reproducting periods, and the geometric locus of object of which movement (in the coordinate system that is adopted) can be expressed as linear equation (as the straight line in the rectangular coordinate system); In arbitrary moment in per two adjacent space coordinate reproducting periods, the movement of objects distance all exists time 0 rank to n order derivative and smoothly (has continuity), and its derivative that is higher than the n rank is 0.Especially, get 0 situation for n, the physical significance of this rate pattern is that the object of which movement speed v is a constant between per two adjacent coordinates; Get 1 situation for n, per two volume coordinate reproducting periods acceleration a are constants, and speed then LINEAR CONTINUOUS changes; And the like.N rank rate pattern basic calculating formula is:

$d=\underset{j=0}{\overset{n}{\mathrm{\Σ}}}\frac{v^{\left(j\right)}}{j+1}{\left(\mathrm{\Δt}\right)}^j,$ (j＝0，...，n)

Wherein, d is a move distance, and v is a speed, and t is the time, v ^(j)Be speed v j (j=0 ..., n) order derivative, Δ t are run duration.

As shown in Figure 1, the present invention at first sets up set C, subclass C by aforementioned manner _mExtract each subclass C again _mPairing volume coordinate and initial sampling instant obtain " volume coordinate-sampling instant " value to sequence { (p _m, t _{M, 1}).Calculate all apart from d (p _m, p _M+1) and construct about each rank speed v _m ^(j)System of equations, have:

$\{d(p_m,p_{m+1})=\underset{j=0}{\overset{n}{\mathrm{\Σ}}}\frac{v_m^{\left(j\right)}}{j+1}{\left({\mathrm{\Δt}}_m\right)}^j\},$ (m＝1，2，...，M-1)

Δ t wherein _m=t _(m+1,1)-t _{(m, 1)}

When n got 0, system of equations was reduced to:

{d(p _m，p _m+1)＝v _m·Δt _m}，(m＝1，2，...，M-1)

Recursion is calculated each rank speed v _m ^(j)And detecting data is unusual.Can draw its top speed and peak acceleration according to the performance index of sampling mobile vehicle (automobile).And with this as basis for estimation.

When n 〉=1,, the boundary condition equation group is arranged because all-order derivative should be continuous on the border:

$\{v_m^{\left(j\right)}{|}_{t=t_{m+\mathrm{1,1}}}=v_{m+\mathrm{1,1}}^{\left(j\right)}\},$ (j＝1，2，..，n；m＝1，2，...，M-1)

According to above-mentioned two system of equations, can be to all m=1,2 ..., M-1 and (n) recursion solves v for j=0 .. _m ^(j)Notice that the quantity of equation is not enough when exponent number n 〉=1, also need to provide and start at subclass (C _m) speed all-order derivative (v ^(j), j=1 ..., initial value n).But start at subclass and be meant the 1st subclass in one group of subclass of continuous application aforementioned equation group.Subclass as the m=1 correspondence is to start at subclass.When in computation process, detecting data exception, will stop recursion, restart recursion from next subclass (being the new subclass of starting at) and calculate.Start at the initial value of the all-order derivative of subclass, can adopt " low order estimation recurrence method " estimation and recursion to obtain.This method at first adopts 0 rank rate pattern to calculate the average velocity of each subclass, estimates the acceleration initial value of subclass, derives the more initial value of high-order speed derivative then.

Recomputate subclass C _mIn the volume coordinate of each sample record, and detecting data is unusual.As, automobile must be sailed in the enterprising every trade of road, has left road if find the position of automobile in the computation process, and just record data mistake or unusual has appearred in explanation, these data is carried out corresponding correction get final product.To all m=1,2 .., M-1 and j=0 ..., the n recursion solves v _m ^(j)Afterwards, by formula { d (p _m, p _M+1)=v _mΔ t _mCalculate each subclass C _m(m=1,2 ..., M) in each sample record r _{M, i}(i=2,3 ..., N _m) with respect to the 1st record r in this set _{M, 1}Straight ahead apart from d _{M, i}By measuring point r _{M, 1}Volume coordinate p _mWith measuring point r _{M, i}And r _{M, 1}Air line distance d _{M, i}, can extrapolate r again _{M, i}" correctly " volume coordinate p _{(m, i)}(i=2,3 ... N _m).And replace originally spatially being gathered in the position coordinates p of same point respectively with the volume coordinate that calculates _m

If be loaded with the constraint condition of the moving object foundation of space orientation equipment and sample devices about space scope and movement velocity (all-order derivative that also comprises the acceleration uniform velocity); the present invention can detect space orientation data exception or error situation; and it is suitably handled, with further raising spatial positioning accuracy.The constraint rule of this example can comprise:

1. the maximal value v of sampling translational speed (to the time) j order derivative _Max ^(j)Usually only get the mobile maximal rate v of sampling _MaxWith peak acceleration a _MaxEnough.This constraint condition can be given according to the performance index (as the top speed and the peak acceleration of truck carrier) of sampling mobile vehicle, also can be rule of thumb given.

2. mobile spatial dimension S samples.This scope can be specified in the mode of enumerating, also can specify with closed expression, or both combinations.As, automobile must be sailed in the enterprising every trade of road, has left road if find the position of automobile in the computation process, and just record data mistake or unusual has appearred in explanation.Can the combining geographic information data realize this constraint.

For example, when gps satellite signal during very poor or satellite losing lock, its given positional information just has very mistake, and spatial dimension constraint condition is not satisfied in its locus, place, or will be increased by the probability that the sampling translational speed of its derivation does not satisfy the constraint of velocity condition.Therefore such positional information can not be as effective input of spatial movement model.For this situation, it is invalid this record data point can be labeled as, and also can estimate possible speed and the locus of automobile during this period, to avoid misapplying the trueness error that invalid data brings as far as possible in conjunction with the car speed that calculates before.

The setting that it will be appreciated by those skilled in the art that the spatial movement model can be set respectively according to the actual motion situation of taking positioning equipment, as long as guarantee its δ _ModelGet final product less than 0.5 α d/ N.

Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those skilled in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.

Claims (5)

1, improves the method for spatial positioning accuracy in a kind of space positioning system, space orientation equipment and parameter sampling equipment place in the moving object to be positioned, the renewal frequency of parameter sampling equipment is greater than the volume coordinate renewal frequency of described space orientation equipment, it is characterized in that this method may further comprise the steps:

(1) sets up the spatial movement model for the moving object that is loaded with space orientation equipment and sample devices, with the motion state of this moving object of correct description on positioning equipment coordinate update cycle time scale;

(2) parameter sampling equipment carries out parameter sampling by the frequency of setting, volume coordinate with sampled data and described space orientation measuring apparatus is combined as " volume coordinate-sampling instant-sampling parameter " element, and form " volume coordinate-sampling instant-sampling parameter " set, this set is orderly about " sampling instant "; In this set, be as the criterion with volume coordinate and set up subclass, promptly the continuous group element that volume coordinate is identical constitutes a subclass; Extract the initial sampling instant of the pairing volume coordinate of each subclass and this subclass, obtain " volume coordinate-sampling instant " element and constitute " volume coordinate-sampling instant " set with this element;

(3) value in basis " volume coordinate-sampling instant " set is to sequence, and the spatial movement model that is adopted, again extrapolate in " volume coordinate-sampling instant-sampling parameter " set, the pairing volume coordinate of each sampling instant is upgraded the former volume coordinate that writes down.

2, improve the method for spatial positioning accuracy in the space positioning system according to claim 1, it is characterized in that, described spatial movement model is based on following condition:

On the meaning of statistics, the α that described spatial movement model average error must be put average headway 0.5 * (d/ N) less than neighbouring sample doubly, here α is the ratio of the volume coordinate renewal frequency of the sample frequency of parameter sampling equipment and space orientation equipment, N is the mean value of sampling parameter number in described " volume coordinate-sampling parameter " subclass, and d is the distance between the volume coordinate of adjacent subset.

3, improve the method for spatial positioning accuracy in the space positioning system according to claim 2, it is characterized in that this method is further comprising the steps of:

Can also set up constraint condition for the moving object that is loaded with space orientation equipment and sample devices, detect space orientation data exception or error situation and handle, with further raising spatial positioning accuracy about space scope or movement velocity.

4, improve the method for spatial positioning accuracy in the GPS according to claim 3, it is characterized in that described constraint condition specifically refers to:

According to the movement velocity threshold value and the acceleration rate threshold of described moving object setting space motion model,, then recomputate the movement velocity of this spatial movement model if the movement velocity or the acceleration that calculate have exceeded respective threshold.

5, improve the method for spatial positioning accuracy in the GPS according to claim 3, it is characterized in that described constraint condition specifically refers to:

If the volume coordinate that calculates has exceeded described moving object route scope, then this volume coordinate is revised.