CN105628053A - Determination method for satellite laser ceilometer pin point geometry positioning errors - Google Patents

Abstract

The invention relates to a determination method for satellite laser ceilometer pin point geometry positioning errors and belongs to the field of laser remote sensing. The problems that an existing pin point geometry positioning error analysis method neglects position and the angle placement errors between a laser measuring system and a carrying platform sensor, only provides partial instant geometry positioning error molds of laser pin points on the premise that height fluctuations of a measured target are not considered and does not analyze extreme values of laser pin point geometry positioning errors are solved. On the basis of the satellite laser ceilometer pin point geometry laser pin point geometry positioning process and error communication theory, the method for comprehensively determining the satellite laser ceilometer laser pin point geometry positioning errors is provided by comprehensively considering the influence on various error sources and plane target fluctuations; the analysis method with the combination of the instant geometry positioning error and the extreme geometry positioning error can achieve comprehensive analysis and evaluation of performance indexes obtained before and after emission of a satellite laser ceilometer.

Description

The decision method of a kind of spaceborne laser altimeter system instrument pin point geometry positioning error

Technical field

The invention belongs to laser remote sensing fields, it is specifically related to the decision method of a kind of spaceborne laser altimeter system instrument pin point geometry positioning error, is applicable to precision analysis and the assessment of spaceborne laser altimeter system instrument observing buoy.

Background technology

Spaceborne laser altimeter system instrument is a kind of laser remote sensing equipment being placed in satellite surface, and it launches the transition time of laser pulse by measuring, it is possible to accurately obtain the distance between laser hypsograph and laser footpoint. The position provided in conjunction with satellite platform and attitude data, thus realize accurately resolving of laser footpoint geometry location coordinate. When making full use of satellite autonomous flight, spaceborne laser altimeter system instrument can be observed and obtain target number elevation model covering the whole world, therefore, spaceborne laser altimeter system instrument has a very wide range of applications in fields such as mapping, Glaciology, geology and thalassography.

As shown in Figure 1, its position fixing process relates to the fusion of laser hypsograph, satellite platform position and attitude sensor three's data to the ultimate principle of spaceborne laser altimeter system instrument pin point geometry location. According to triangular vector method, the geometric vector of laser footpoint on tested celestial body surface can represent and be

$\stackrel{\→}{oF}=(\stackrel{\→}{AL}+\stackrel{\→}{LF})+(\stackrel{\→}{oP}+\stackrel{\→}{PA})$

Wherein,Represent the measurement vector of laser hypsograph,Represent the position offset vector between laser hypsograph and attitude sensor,Represent the measurement vector of position transducer,Represent the position offset vector between attitude sensor and position transducer.

Consider in spaceborne laser altimeter system instrument laser footpoint geometry location process, there is certain error in the arrangement of each sensor and observed data thereof, then the geometry location coordinate of laser footpoint can be subject to the impact in multiple error source, mainly comprises: the Orbit Error of the arrangement angular error of the laser ranging error of spaceborne laser altimeter system instrument, the attitude angle error of satellite platform, laser guide angular error, each sensor and positionerror thereof, satellite platform. Simultaneously, when spaceborne laser altimeter system instrument real work, the measuring states such as the attitude of its laser guide and satellite platform can change, then laser footpoint geometry location error there will be certain fluctuation, therefore, the geometry location error of reasonable analysis laser footpoint, has a very important role for the technical indicator of assessment spaceborne laser altimeter system instrument and the application of achievement thereof.

At present, had the document about laser footpoint geometry location errot analysis of some classics, as based on difference model analytical method (M, etal.Asimplifiedanalyticalmodelfora-priorilidarpoint-pos itioningerrorestimationandareviewoflidarerrorsources.Pho togrammetricEngineering&RemoteSensing, 75 (12): 1425-1439,2009; DanJ, etal.RandomErrorModelingandAnalysisofAirborneLidarSystem s.IEEETransactionsonGeoscienceandRemoteSensing, 52 (7): 3885-3894,2014), based on the analytical method (Liu Shaochuan of medial error form, Deng. the positioning principle of machine load three-dimensional imaging instrument and errot analysis. mapping journal, 28 (2): 121-127,1999; Ma Yue, etc. spaceborne laser altimeter system system vertical error is observed on ground and analyzes. infrared and laser engineering, 44 (3): 1042-1047,2015) etc. These methods have ignored the position between laser measurement system and lift-launch platform sensor and angle installation error, under the prerequisite not considering measured target height relief, provide only the instantaneous geometry location error model of the part of laser footpoint, the extreme value of laser footpoint geometry location error is not analyzed simultaneously. Thus, adopting these methods only can observe target for horizontal plane, analysis part error factor, on the impact of the instantaneous positioning error of laser footpoint, cannot realize the comprehensive assessment of spaceborne laser altimeter system instrument laser footpoint geometry location error.

Summary of the invention

The present invention mainly solves technical problem existing in existing analytical procedure; Provide a kind of when considering various error source, measuring state and planar target and rise and fall, taking the communication theory of medial error as foundation, realize transient analysis and the extreme value analysis of spaceborne laser altimeter system instrument laser footpoint error, thus qualitative assessment spaceborne laser altimeter system instrument laser footpoint geometry location error comprehensively.

The above-mentioned technical problem of the present invention is mainly solved by following technical proposals:

The decision method of a kind of spaceborne laser altimeter system instrument pin point geometry positioning error, it is characterised in that, concrete grammar is:

Step 1, initial parameter according to spaceborne laser altimeter system instrument pin point geometry positioning error, calculate under attitude surving coordinate system, by the pin point geometry positioning error component caused by angular error, range finding error and positionerror, wherein, the initial parameter of described spaceborne laser altimeter system instrument pin point geometry positioning error comprises:

The hardware error parameter of parameter one, laser hypsograph: comprise laser guide angular error and hardware range finding error, settle angular error and installation position error;

Parameter two, satellite platform error parameter: arrangement angular error and the installation position error comprising the attitude angle error (comprising angle of roll error, angle of pitch error and track angle error) of satellite platform, the Orbit Error of satellite platform, attitude sensor and position transducer;

Parameter three, atmospheric delay correction error parameter on Laser emission direction;

Parameter four, measuring state parameter: comprise the rotation relationship between spaceborne laser altimeter system instrument laser guide angle, the attitude angle of satellite platform, attitude surving coordinate system and celestial body system of coordinates;

Parameter five, planar target parameter: comprise target along the obliquity on rail and vertical rail direction;

The orbit altitude of parameter six, satellite;

Calculate by the pin point geometry positioning error component caused by angular error, range finding error and positionerror, comprise following sub-step:

Step 1.1, calculates the root-mean-square error d �� of spaceborne laser altimeter system instrument laser ranging_i:

${\mathrm{d\ρ}}_i=\sqrt{{\mathrm{d\ρ}}_s^2+{\mathrm{\ρ}}_i^2\[{\tan }^2({\mathrm{\φ}}_i+s_x){\mathrm{d\φ}}_x^2+\frac{{\tan }^2{s}_y{\cos }^2{s}_x{\cos }^2{\mathrm{\φ}}_i}{{\cos }^2({\mathrm{\φ}}_i+s_x)}{\mathrm{d\φ}}_y^2\]+{\mathrm{d\ρ}}_a^2}$

In formula, d ��_sWith d ��_aIt is respectively laser hypsograph hardware range finding error and atmospheric delay correction error, (d ��_x,d��_y) and (s_x,s_y) be respectively along the laser guide angular error on rail and vertical rail direction and target tilt angle, ��_iFor laser guide angle, it is the angle launching laser direction and nadir direction, ��_i=�� �� �� (i-1), i=1,2,3....., int (��_max/ �� ��)+1, wherein, function int represents numerical value rounding operation, and �� �� is the angle intervals at laser guide angle, 0.01 ��ܦ� ����1 ��, ��_maxFor maximum laser guide angle, 0 ��ܧ�_max�� 30 ��, ��_iFor laser ranging value, ��_i��H/cos��_i, H is the orbit altitude of satellite;

Step 1.2, calculates under attitude surving coordinate system, the component dx of laser footpoint geometry location error_ij�� dy_ijAnd dz_ij:

$\begin{array}{c}{\mathrm{dy}}_{ij}^2={\left(a_5{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i\right)}^2{\mathrm{d\γ}}_x^2+{(a_4{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i-a_6{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i)}^2{\mathrm{d\γ}}_y^2+{\left(a_5{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i\right)}^2{\mathrm{d\γ}}_z^2\\ +{(a_1{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i+a_3{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i)}^2{\mathrm{d\θ}}^2+{(a_7{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i+a_9{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i)}^2{\mathrm{d\ω}}^2\\ +{(a_4{\mathrm{sin\φ}}_i+a_6{\mathrm{cos\φ}}_i)}^2{\mathrm{d\ρ}}_i^2+(a_4^2{\mathrm{dr}}_x^2+a_5^2{\mathrm{dr}}_y^2+a_6^2{\mathrm{dr}}_z^2)\end{array}$

In formula, d ��_x��d��_yWith d ��_zFor synthesis angular error, they can represent and are: ${\mathrm{d\γ}}_x^2={\mathrm{d\φ}}_x^2+{\mathrm{d\α}}_x^2+{\mathrm{d\β}}_x^2,{\mathrm{d\γ}}_y^2={\mathrm{d\φ}}_y^2+{\mathrm{d\α}}_y^2+{\mathrm{d\β}}_y^2,{\mathrm{d\γ}}_z^2={\mathrm{d\φ}}_z^2+{\mathrm{d\α}}_z^2+{\mathrm{d\β}}_z^2,$ Wherein, d ��_zFor the component of laser guide angular error on nadir direction, (d ��_x,d��_y,d��_z) it is the arrangement angular error of attitude sensor under satellite platform system of coordinates, (d ��_x,d��_y,d��_z) and (dr_x,dr_y,dr_z) it is respectively the arrangement angular error of spaceborne laser altimeter system instrument under satellite body system of coordinates and installation position error;It is satellite platform attitude angle error, a_kThe element that (k=1,2,3.....9) is attitude matrix, they meet following relational expression:

In formula,Being satellite platform attitude angle, their value is identical, and all satisfied: ��_j=�� �� �� (j-1), j=1,2,3....., int (��_max/ �� ��)+1, wherein, �� �� is the angle intervals of attitude angle, 0.01 ��ܦ� �ҡ�1 ��, ��_maxFor maximum attitude angle, 0 ��ܦ�_max�� 90 ��;

Step 2, according to the rotation relationship between attitude surving coordinate system and celestial body system of coordinates, calculates the instantaneous geometry location error of laser footpoint under celestial body system of coordinates;

Step 3, by the error value of statistics laser footpoint geometry location or based on error extreme value model, calculates maximum value and the minimum value of pin point geometry positioning error.

At the decision method of above-mentioned a kind of spaceborne laser altimeter system instrument pin point geometry positioning error, in described step 1, according to the rotation relationship between attitude surving coordinate system and celestial body system of coordinates, calculate at the celestial body system of coordinates leftover bits and pieces instantaneous geometry location error component dX of point_ij��dY_ijAnd dZ_ij:

${\mathrm{dX}}_{ij}^2=m_1^2{\mathrm{dx}}_{ij}^2+m_2^2{\mathrm{dy}}_{ij}^2+m_3^2{\mathrm{dz}}_{ij}^2+{\mathrm{dX}}_g^2$

${\mathrm{dY}}_{ij}^2=m_4^2{\mathrm{dx}}_{ij}^2+m_5^2{\mathrm{dy}}_{ij}^2+m_6^2{\mathrm{dz}}_{ij}^2+{\mathrm{dY}}_g^2$

${\mathrm{dZ}}_{ij}^2=m_7^2{\mathrm{dx}}_{ij}^2+m_8^2{\mathrm{dy}}_{ij}^2+m_9^2{\mathrm{dz}}_{ij}^2+{\mathrm{dZ}}_g^2$

In formula, m_lThe element that (l=1,2,3...9) is the rotation matrix between attitude surving coordinate system and celestial body system of coordinates; (dX_g,dY_g,dZ_g) it is the Orbit Error of satellite under celestial body system of coordinates.

At the decision method of above-mentioned a kind of spaceborne laser altimeter system instrument pin point geometry positioning error, in described step 3, calculate maximum value and the minimum value of pin point geometry positioning error, comprise following sub-step:

Step 3.1, if whole measuring state parameters of spaceborne laser altimeter system instrument are known, then searches the laser footpoint each component (dX of instantaneous geometry location error_ij,dY_ij,dZ_ij) extreme value, the statistics maximum value of pin point geometry positioning error and minimum value:

dX_max=max (dX_ij), dY_max=max (dY_ij), dZ_max=max (dZ_ij)

dX_min=min (dX_ij), dY_min=min (dY_ij), dZ_min=min (dZ_ij)

In formula, function max and min represents and asks maximum value and minimum operation; (dX_max,dY_max,dZ_max) and (dX_min,dY_min,dZ_min) it is the maximum value of pin point geometry positioning error and minimum value;

Step 3.2, if spaceborne laser altimeter system instrument part measuring state unknown parameters, according to the extreme value error model of pin point geometry location, calculates maximum value and the minimum value of pin point geometry positioning error:

${\mathrm{dX}}_{max}={\mathrm{dY}}_{max}={\mathrm{dZ}}_{max}=\sqrt{{\left({\mathrm{\ρ}}_{max}{\mathrm{d\γ}}_{max}\right)}^2+{\left({\mathrm{\ρ}}_{max}{\mathrm{d\σ}}_{max}\right)}^2+{\mathrm{dr}}_{max}^2+{\mathrm{dV}}_{max}^2}$

${\mathrm{dX}}_{\min }={\mathrm{dY}}_{\min }={\mathrm{dZ}}_{\min }=\sqrt{{\mathrm{d\ρ}}_{min}^2+{\mathrm{dr}}_{min}^2+{\mathrm{dV}}_{min}^2}$

In formula, ��_maxIt is the maximum value of laser ranging, (d ��_min,d��_max)��(d��_min,d��_max)��(dr_min,dr_max)��(d��_min,d��_max)��(dV_min,dV_max) represent the minimum value and maximum value of synthesizing angular error, attitude angle error, the installation position error of spaceborne laser altimeter system instrument, error of finding range and Orbit Error respectively.

Therefore, tool of the present invention has the following advantages: based on the communication theory of spaceborne laser altimeter system instrument laser footpoint geometry location process and error, by considering multiple error source and the impact of planar target fluctuating, it is proposed that judge the method for the geometry location error of spaceborne laser altimeter system instrument laser footpoint: the analytical procedure that instantaneous geometry location error combines with extreme value geometry location error comprehensively. The decision method of laser footpoint geometry location error, is specially adapted to the optimization design of hardware error parameter and the evaluation analysis of performance index thereof of spaceborne laser altimeter system instrument.

Accompanying drawing explanation

Fig. 1 is the ultimate principle of laser hypsograph laser footpoint geometry location.

Fig. 2 is the calculation process of spaceborne laser altimeter system instrument laser footpoint geometry location error.

Fig. 3 a is the relation curve at embodiment laser ranging error and laser guide angle.

Fig. 3 b is embodiment International Celestial Reference System system of coordinates leftover bits and pieces point geometry location error in the x direction.

Fig. 3 c is embodiment International Celestial Reference System system of coordinates leftover bits and pieces point geometry location error in y-direction.

Fig. 3 d is embodiment International Celestial Reference System system of coordinates leftover bits and pieces point geometry location error in a z-direction.

Fig. 4 a is the international earth based coordinate system leftover bits and pieces point of embodiment geometry location error in the X direction.

Fig. 4 b is the international earth based coordinate system leftover bits and pieces point of embodiment geometry location error in the Y direction.

Fig. 4 c is the international earth based coordinate system leftover bits and pieces point of embodiment geometry location error in z-direction.

Embodiment

Below by the analysis embodiment that ground is observed spaceborne laser altimeter system instrument pin point geometry positioning error, and by reference to the accompanying drawings, the technical scheme of the present invention is described in further detail.

Embodiment:

One, first introduce the concrete grammar flow process of the present invention, mainly comprise the following steps:

1. input the initial parameter of spaceborne laser altimeter system instrument pin point geometry positioning error, comprise following process:

(1.1) input the hardware error parameter of laser hypsograph, comprise laser guide angular error and hardware range finding error, settle angular error and installation position error;

(1.2) input satellite platform error parameter, comprise arrangement angular error and the installation position error of the attitude angle error (comprising angle of roll error, angle of pitch error and track angle error) of satellite platform, the Orbit Error of satellite platform, attitude sensor and position transducer;

(1.3) the atmospheric delay correction error parameter on Laser emission direction is inputted;

(1.4) input measurement state parameter, comprises the rotation matrix between the attitude angle of spaceborne laser altimeter system instrument laser guide angle and satellite platform, International Celestial Reference System system of coordinates (attitude surving coordinate system) and international earth based coordinate system (celestial body system of coordinates);

(1.5) input plane target component, comprises target along the obliquity on rail and vertical rail direction;

(1.6) orbit altitude of satellite is inputted.

2. calculate under International Celestial Reference System system of coordinates, by the pin point geometry positioning error component caused by angular error, range finding error and positionerror, comprise following process:

(2.1) the root-mean-square error d �� of spaceborne laser altimeter system instrument laser ranging is calculated_i:

${\mathrm{d\ρ}}_i=\sqrt{{\mathrm{d\ρ}}_s^2+{\mathrm{\ρ}}_i^2\[{\tan }^2({\mathrm{\φ}}_i+s_x){\mathrm{d\φ}}_x^2+\frac{{\tan }^2{s}_y{\cos }^2{s}_x{\cos }^2{\mathrm{\φ}}_i}{{\cos }^2({\mathrm{\φ}}_i+s_x)}{\mathrm{d\φ}}_y^2\]+{\mathrm{d\ρ}}_a^2}$

In formula, d ��_sWith d ��_aIt is respectively laser hypsograph hardware range finding error and atmospheric delay correction error, (d ��_x,d��_y) and (s_x,s_y) be respectively along the laser guide angular error on rail and vertical rail direction and target tilt angle, ��_iFor laser guide angle, it is the angle launching laser direction and nadir direction, ��_i=0.1 �� �� i, i=1,2,3....., 301, ��_iFor laser ranging value, ��_i��H/cos��_i, H is the orbit altitude of satellite.

(2.2) calculate under International Celestial Reference System system of coordinates, the component dx of laser footpoint geometry location error_ij��dy_ijAnd dz_ij:

$\begin{array}{c}{\mathrm{dy}}_{ij}^2={\left(a_5{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i\right)}^2{\mathrm{d\γ}}_x^2+{(a_4{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i-a_6{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i)}^2{\mathrm{d\γ}}_y^2+{\left(a_5{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i\right)}^2{\mathrm{d\γ}}_z^2\\ +{(a_1{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i+a_3{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i)}^2{\mathrm{d\θ}}^2+{(a_7{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i+a_9{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i)}^2{\mathrm{d\ω}}^2\\ +{(a_4{\mathrm{sin\φ}}_i+a_6{\mathrm{cos\φ}}_i)}^2{\mathrm{d\ρ}}_i^2+(a_4^2{\mathrm{dr}}_x^2+a_5^2{\mathrm{dr}}_y^2+a_6^2{\mathrm{dr}}_z^2)\end{array}$

In formula, d ��_x��d��_yWith d ��_zFor synthesis angular error, they can represent and are: ${\mathrm{d\γ}}_x^2={\mathrm{d\φ}}_x^2+{\mathrm{d\α}}_x^2+{\mathrm{d\β}}_x^2,{\mathrm{d\γ}}_y^2={\mathrm{d\φ}}_y^2+{\mathrm{d\α}}_y^2+{\mathrm{d\β}}_y^2,{\mathrm{d\γ}}_z^2={\mathrm{d\φ}}_z^2+{\mathrm{d\α}}_z^2+{\mathrm{d\β}}_z^2,$ Wherein, d ��_zFor the component of laser guide angular error on nadir direction, (d ��_x,d��_y,d��_z) it is the arrangement angular error of attitude sensor under satellite platform system of coordinates, (d ��_x,d��_y,d��_z) and (dr_x,dr_y,dr_z) it is respectively the arrangement angular error of spaceborne laser altimeter system instrument under satellite body system of coordinates and installation position error.It it is satellite platform attitude angle (angle of roll, the angle of pitch and track angle) error. a_kThe element that (k=1,2,3...9) is attitude matrix, they meet following relational expression:

In formula,Being satellite platform attitude angle, their value is identical, and all satisfied: ��_j=0.1 �� �� (j-1), j=1,2,3....., 901.

In this step, target is the flat diffuse reflective body with certain altitude fluctuating, and the scope of its obliquity covers 0 �㡫60 ��; In addition, error of finding range has considered the impact of the multiple factors such as laser hypsograph hardware system, target tilt effect and atmosphere delay.

3. calculate the instantaneous geometry location error component dX of laser footpoint under international earth based coordinate system_ij��dY_ijAnd dZ_ij:

${\mathrm{dX}}_{ij}^2=m_1^2{\mathrm{dx}}_{ij}^2+m_2^2{\mathrm{dy}}_{ij}^2+m_3^2{\mathrm{dz}}_{ij}^2+{\mathrm{dX}}_g^2$

${\mathrm{dY}}_{ij}^2=m_4^2{\mathrm{dx}}_{ij}^2+m_5^2{\mathrm{dy}}_{ij}^2+m_6^2{\mathrm{dz}}_{ij}^2+{\mathrm{dY}}_g^2$

${\mathrm{dZ}}_{ij}^2=m_7^2{\mathrm{dx}}_{ij}^2+m_8^2{\mathrm{dy}}_{ij}^2+m_9^2{\mathrm{dz}}_{ij}^2+{\mathrm{dZ}}_g^2$

In formula, m_l(l=1,2,3...9) is the element of the rotation matrix between International Celestial Reference System system of coordinates and international earth based coordinate system. (dX_g,dY_g,dZ_g) it is the Orbit Error of satellite under international earth based coordinate system.

4. calculate maximum value and the minimum value of pin point geometry positioning error, comprise following process:

(4.1) if spaceborne laser altimeter system instrument whole measuring state parameter is known, then the laser footpoint each component (dX of instantaneous geometry location error is searched_ij,dY_ij,dZ_ij) extreme value, statistics obtains maximum value and the minimum value of pin point geometry positioning error:

dX_max=max (dX_ij), dY_max=max (dY_ij), dZ_max=max (dZ_ij)

dX_min=min (dX_ij), dY_min=min (dY_ij), dZ_min=min (dZ_ij)

In formula, function max and min represents and asks maximum value and minimum operation. (dX_max,dY_max,dZ_max) and (dX_min,dY_min,dZ_min) it is the maximum value of pin point geometry positioning error and minimum value.

(4.2) if spaceborne laser altimeter system instrument part measuring state unknown parameters, according to the extreme value error model of pin point geometry location, maximum value and the minimum value of pin point geometry positioning error is calculated:

${\mathrm{dX}}_{max}={\mathrm{dY}}_{max}={\mathrm{dZ}}_{max}=\sqrt{{\left({\mathrm{\ρ}}_{max}{\mathrm{d\γ}}_{max}\right)}^2+{\left({\mathrm{\ρ}}_{max}{\mathrm{d\σ}}_{max}\right)}^2+{\mathrm{dr}}_{max}^2+{\mathrm{dV}}_{max}^2}$

${\mathrm{dX}}_{\min }={\mathrm{dY}}_{\min }={\mathrm{dZ}}_{\min }=\sqrt{{\mathrm{d\ρ}}_{min}^2+{\mathrm{dr}}_{min}^2+{\mathrm{dV}}_{min}^2}$

In formula, ��_maxIt is the maximum value of laser ranging, (d ��_min,d��_max)��(d��_min,d��_max)��(dr_min,dr_max)��(d��_min,d��_max)��(dV_min,dV_max) represent the minimum value and maximum value of synthesizing angular error, attitude angle error, the installation position error of spaceborne laser altimeter system instrument, error of finding range and Orbit Error respectively.

In this step, fully consider the known two kinds of situations with part measuring state the unknown of spaceborne laser altimeter system instrument measuring state, it is achieved the maximum value of laser footpoint geometry location error and the solution calculation and Analysis of minimum value.

Two, it is the specific embodiment adopting the inventive method below:

1. input the initial parameter of spaceborne laser altimeter system instrument pin point geometry positioning error assessment, comprising the input hardware error parameter of laser hypsograph, satellite platform error parameter, atmospheric delay correction error parameter, measuring state parameter, planar target parameter, satellite orbit height etc., its parameter name, symbol and numerical value are shown in Table 1;

The initial parameter of table 1 pin point geometry positioning error assessment

2. calculate laser ranging error d ��_iWith the error component dx of laser footpoint geometry location under International Celestial Reference System system of coordinates_ij��dy_ijAnd dz_ij, the relation of they and laser guide angle and satellite attitude angle is shown in shown in Fig. 3 (a) and Fig. 3 (b)��Fig. 3 (d) respectively;

3. calculate the instantaneous geometry location error dX of laser footpoint under international earth based coordinate system_ij��dY_ijAnd dZ_ij, the distribution rule of they and laser guide angle and satellite attitude angle is shown in shown in Fig. 4 (a)��Fig. 4 (c);

4. calculate maximum value and the minimum value of laser footpoint geometry location error: search dX_ij��dY_ijAnd dZ_ijMaximum value and minimum value, statistics obtains the extreme value of laser footpoint geometry location error in the x, y, and z directions: (dX_max,dY_max,dZ_max)=(5.14m, 5.36m, 5.54m), (dX_min,dY_min,dZ_min)=(2.71m, 3.99m, 0.42m).

Three, checking is analyzed

Owing to motion, the nutating of international earth framework and the earth are relevant with pole shifting, it is every year all in change, so the rotation matrix between International Celestial Reference System system of coordinates and international earth based coordinate system is the function of time, the moment that it arrives ground with laser pulse is relevant. Before spaceborne laser altimeter system instrument is launched, it is contemplated that be unknown to this rotation matrix, then the extreme value of laser footpoint geometry location coordinate cannot be analyzed. Adopt the extreme value error model of pin point geometry location in the present invention, it is possible to calculate the extreme value that statistics obtains laser footpoint geometry location error in the x, y, and z directions: dX_max=dY_max=dZ_max=5.54m, dX_min=dY_min=dZ_min=0.42m.

Obviously, the error extreme value that the extreme value error model located by pin point geometry calculates covers the error extreme value under all measuring states, this is conducive to carrying out the spaceborne laser altimeter system instrument performance before transmitting comprehensively judging and analyzing, to verify the matching degree of its technical indicator.

Specific embodiment described herein is only to the present invention's spirit explanation for example. Described specific embodiment can be made various amendment or supplements or adopt similar mode to substitute by those skilled in the art, but can't deviate the spirit of the present invention or surmount the scope that appended claims defines.

Claims (3)

1. the decision method of a spaceborne laser altimeter system instrument pin point geometry positioning error, it is characterised in that, concrete grammar is:

Step 1, initial parameter according to spaceborne laser altimeter system instrument pin point geometry positioning error, calculate under attitude surving coordinate system, by the pin point geometry positioning error component caused by angular error, range finding error and positionerror, wherein, the initial parameter of described spaceborne laser altimeter system instrument pin point geometry positioning error comprises:

The hardware error parameter of parameter one, laser hypsograph: comprise laser guide angular error and hardware range finding error, settle angular error and installation position error;

Parameter two, satellite platform error parameter: arrangement angular error and the installation position error comprising the attitude angle error (comprising angle of roll error, angle of pitch error and track angle error) of satellite platform, the Orbit Error of satellite platform, attitude sensor and position transducer;

Parameter three, atmospheric delay correction error parameter on Laser emission direction;

Parameter four, measuring state parameter: comprise the rotation relationship between spaceborne laser altimeter system instrument laser guide angle, the attitude angle of satellite platform, attitude surving coordinate system and celestial body system of coordinates;

Parameter five, planar target parameter: comprise target along the obliquity on rail and vertical rail direction;

The orbit altitude of parameter six, satellite;

Calculate by the pin point geometry positioning error component caused by angular error, range finding error and positionerror, comprise following sub-step:

Step 1.1, calculates the root-mean-square error d �� of spaceborne laser altimeter system instrument laser ranging_i:

${\mathrm{d\ρ}}_i=\sqrt{{\mathrm{d\ρ}}_s^2+{\mathrm{\ρ}}_i^2\[{\tan }^2({\mathrm{\φ}}_i+s_x){\mathrm{d\φ}}_x^2+\frac{{\tan }^2{s}_y{\cos }^2{s}_x{\cos }^2{\mathrm{\φ}}_i}{{\cos }^2({\mathrm{\φ}}_i+s_x)}{\mathrm{d\φ}}_y^2\]+{\mathrm{d\ρ}}_a^2}$

In formula, d ��_sWith d ��_aIt is respectively laser hypsograph hardware range finding error and atmospheric delay correction error, (d ��_x,d��_y) and (s_x,s_y) be respectively along the laser guide angular error on rail and vertical rail direction and target tilt angle, ��_iFor laser guide angle, it is the angle launching laser direction and nadir direction, ��_i=�� �� �� (i-1), i=1,2,3....., int (��_max/ �� ��)+1, wherein, function int represents numerical value rounding operation, and �� �� is the angle intervals at laser guide angle, 0.01 ��ܦ� ����1 ��, ��_maxFor maximum laser guide angle, 0 ��ܧ�_max�� 30 ��, ��_iFor laser ranging value, ��_i��H/cos��_i, H is the orbit altitude of satellite;

Step 1.2, calculates under attitude surving coordinate system, the component dx of laser footpoint geometry location error_ij��dy_ijAnd dz_ij:

$\begin{array}{c}{\mathrm{dy}}_{ij}^2={\left(a_5{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i\right)}^2{\mathrm{d\γ}}_x^2+{\left(a_4{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i-a_6{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i\right)}^2{\mathrm{d\γ}}_y^2+{\left(a_5{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i\right)}^2{\mathrm{d\γ}}_z^2\\ +{\left(a_1{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i+a_3{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i\right)}^2{\mathrm{d\θ}}^2+{\left(a_7{\mathrm{\ρ}}_i{\mathrm{sin\φ}}_i+a_9{\mathrm{\ρ}}_i{\mathrm{cos\φ}}_i\right)}^2{\mathrm{d\ω}}^2\\ +{\left(a_4{\mathrm{sin\φ}}_i+a_6{\mathrm{cos\φ}}_i\right)}^2{\mathrm{d\ρ}}_i^2+\left(a_4^2{\mathrm{dr}}_x^2+a_5^2{\mathrm{dr}}_y^2+a_6^2{\mathrm{dr}}_z^2\right)\end{array}$

In formula, d ��_x��d��_yWith d ��_zFor synthesis angular error, they can represent and are: ${\mathrm{d\γ}}_x^2={\mathrm{d\φ}}_x^2+{\mathrm{d\α}}_x^2+{\mathrm{d\β}}_x^2,{\mathrm{d\γ}}_y^2={\mathrm{d\φ}}_y^2+{\mathrm{d\α}}_y^2+{\mathrm{d\β}}_y^2,{\mathrm{d\γ}}_z^2={\mathrm{d\φ}}_z^2+{\mathrm{d\α}}_z^2+{\mathrm{d\β}}_z^2,$ Wherein, d ��_zFor the component of laser guide angular error on nadir direction, (d ��_x,d��_y,d��_z) it is the arrangement angular error of attitude sensor under satellite platform system of coordinates, (d ��_x,d��_y,d��_z) and (dr_x,dr_y,dr_z) it is respectively the arrangement angular error of spaceborne laser altimeter system instrument under satellite body system of coordinates and installation position error;It is satellite platform attitude angle error, a_kThe element that (k=1,2,3.....9) is attitude matrix, they meet following relational expression:

In formula,Being satellite platform attitude angle, their value is identical, and all satisfied: ��_j=�� �� �� (j-1), j=1,2,3....., int (��_max/ �� ��)+1, wherein, �� �� is the angle intervals of attitude angle, 0.01 ��ܦ� �ҡ�1 ��, ��_maxFor maximum attitude angle, 0 ��ܦ�_max�� 90 ��;

Step 2, according to the rotation relationship between attitude surving coordinate system and celestial body system of coordinates, calculates the instantaneous geometry location error of laser footpoint under celestial body system of coordinates;

Step 3, by the error value of statistics laser footpoint geometry location or based on error extreme value model, calculates maximum value and the minimum value of pin point geometry positioning error.

2. the decision method of a kind of spaceborne laser altimeter system instrument pin point geometry positioning error according to claim 1, it is characterized in that, in described step 1, according to the rotation relationship between attitude surving coordinate system and celestial body system of coordinates, calculate at the celestial body system of coordinates leftover bits and pieces instantaneous geometry location error component dX of point_ij��dY_ijAnd dZ_ij:

${\mathrm{dX}}_{ij}^2=m_1^2{\mathrm{dx}}_{ij}^2+m_2^2{\mathrm{dy}}_{ij}^2+m_3^2{\mathrm{dz}}_{ij}^2+{\mathrm{dX}}_g^2$

${\mathrm{dY}}_{ij}^2=m_4^2{\mathrm{dx}}_{ij}^2+m_5^2{\mathrm{dy}}_{ij}^2+m_6^2{\mathrm{dz}}_{ij}^2+{\mathrm{dY}}_g^2$

${\mathrm{dZ}}_{ij}^2=m_7^2{\mathrm{dx}}_{ij}^2+m_8^2{\mathrm{dy}}_{ij}^2+m_9^2{\mathrm{dz}}_{ij}^2+{\mathrm{dZ}}_g^2$

In formula, m_lThe element that (l=1,2,3...9) is the rotation matrix between attitude surving coordinate system and celestial body system of coordinates; (dX_g,dY_g,dZ_g) it is the Orbit Error of satellite under celestial body system of coordinates.

3. the decision method of a kind of spaceborne laser altimeter system instrument pin point geometry positioning error according to claim 1, it is characterised in that, in described step 3, calculate maximum value and the minimum value of pin point geometry positioning error, comprise following sub-step:

Step 3.1, if whole measuring state parameters of spaceborne laser altimeter system instrument are known, then searches the laser footpoint each component (dX of instantaneous geometry location error_ij,dY_ij,dZ_ij) extreme value, the statistics maximum value of pin point geometry positioning error and minimum value:

dX_max=max (dX_ij), dY_max=max (dY_ij), dZ_max=max (dZ_ij)

dX_min=min (dX_ij), dY_min=min (dY_ij), dZ_min=min (dZ_ij)

In formula, function max and min represents and asks maximum value and minimum operation; (dX_max,dY_max,dZ_max) and (dX_min,dY_min,dZ_min) it is the maximum value of pin point geometry positioning error and minimum value;

Step 3.2, if spaceborne laser altimeter system instrument part measuring state unknown parameters, according to the extreme value error model of pin point geometry location, calculates maximum value and the minimum value of pin point geometry positioning error:

${\mathrm{dX}}_{max}={\mathrm{dY}}_{max}={\mathrm{dZ}}_{max}=\sqrt{{\left({\mathrm{\ρ}}_{max}{\mathrm{d\γ}}_{max}\right)}^2+{\left({\mathrm{\ρ}}_{max}{\mathrm{d\σ}}_{max}\right)}^2+{\mathrm{dr}}_{max}^2+{\mathrm{dV}}_{max}^2}$

${\mathrm{dX}}_{\min }={\mathrm{dY}}_{\min }={\mathrm{dZ}}_{\min }=\sqrt{{\mathrm{d\ρ}}_{\min }^2+{\mathrm{dr}}_{\min }^2+{\mathrm{dV}}_{\min }^2}$

In formula, ��_maxIt is the maximum value of laser ranging, (d ��_min,d��_max)��(d��_min,d��_max)��(dr_min,dr_max)��(d��_min,d��_max)��(dV_min,dV_max) represent the minimum value and maximum value of synthesizing angular error, attitude angle error, the installation position error of spaceborne laser altimeter system instrument, error of finding range and Orbit Error respectively.