CN106353714A - Static locating method for mars lander based on surrounder - Google Patents

Abstract

The invention provides a static locating method for a mars lander based on a surrounder, based on tracking and measuring a detector, the wireless distance and speed measurement between the surrounder and the lander is measured; the surrounder emits a wireless signal in a manner of double-trip measurement; and after being in transparent transmission of the lander, the wireless signal is sent to the earth to be treated by the mars measuring data. The landing locating precision obtained by multi-circle measurement of the lander can reach dozens km magnitude. The static locating method for a mars lander based on a surrounder provided in the invention can help the ground tracking and measuring and make up the defects of long underground flame distance and hard tracking and measuring difficulty of the lander; and the use ratio of the equipment on the mars can be improved without increasing extract cost by the equipment on the surrounder.

Description

A kind of Mars landing device static immobilization method based on cincture device

Technical field

The present invention relates to a kind of be related to the mode of relay station based on the Mars landing device static immobilization method around device, belong to In field of deep space exploration.

Background technology

Mars is a terrestrial planet in the solar system, and the environmental condition of Mars is the most close with the earth, and research Mars is favourable In recognizing the earth and solar formation and evolutionary process further；Mars has atmosphere, and earth's surface has water-ice, finds life It is one of target of current survey of deep space concern.China has set about plan first autonomous Mars probes of transmitting and has realized Mars Detect.Lander in detection mission will enter martian atmosphere and land in martian surface, due to recognizing not to Mars environment It is contemplated that landing precision is limited, how quick high accuracy ground determines that the landing position of lander becomes extremely urgent asking to foot Topic.

Mars probes flight overall process is based on ground based radio navigation and Orbit simulation.Detector is successfully captured Afterwards, separate with lander around device.Lander successfully lands after energy meter, because the earth is far apart with Mars, is landed Device Power Limitation, ground is larger facing to the tracking measurement difficulty of land device.Utilize single cincture device in deep space field to lander Position Research is less.

Content of the invention

Far apart with Mars for the earth, by lander Power Limitation, ground is difficult facing to the tracking measurement of land device Larger the problems such as, the present invention provides a kind of Mars landing device static immobilization method based on cincture device, makes full use of around device star Upper equipment, does not increase extra cost, improves the utilization rate of on-board equipment.

The above-mentioned purpose of the present invention is achieved through the following technical solutions:

A kind of based on around device Mars landing device static immobilization method it is characterised in that: when Mars landing device land in After martian surface, introduce around device as relay station on the basis of ground control station is to lander tracking measurement, using round trip The mode measuring, obtains around device and lander relative position relation, and Cross-Link measurement data is passed back the earth as auxiliary survey Amount, improves lander in areographic positional precision.

Described cincture device, as relay station, adopts x band communication around between device and ground, adopts uhf and between lander Band communication.

The described tracking measurement mode main around device and lander is ground based radio navigation, adopts to around device Vlbi measures.

The described position around device and velocity accuracy are the key factors affecting lander positional precision, around the position of device Put higher with velocity accuracy, the positioning precision of lander is higher.

Described around device, lander carried out with round trip and test the speed range finding, by cincture device electromagnetic signals, through lander After transparent forwarding, signal is passed back around device, is processed by passing signal back the earth around device.Measured by the multi-turn around device The lander positioning precision obtaining eventually can reach more than ten kilometers.

Implement and comprise the steps:

Step 1: determine around the communication segmental arc between device and lander, mainly consider both wireless communication distance ρ and two The observability of person's sight line.Wherein take ρ ＜ 4000km；The position vector making lander to Mars barycenter isLander is to cincture The position vector of device isAngle between the two is α, then the condition around the segmental arc that can communicate between device and lander is:

180-α≥90

There is the restriction at the 5o elevation angle in view of lander reception antenna, then the condition of the segmental arc that finally can communicate is:

$\mathrm{\α}={\cos }^{-1}\left(\frac{{\stackrel{\→}{s}}_1\·{\stackrel{\→}{s}}_2}{\left|{\stackrel{\→}{s}}_1\right|\·\left|{\stackrel{\→}{s}}_1\right|}\right)\≤85$

Step 2: known on the basis of device position and speed, set up and survey around the round trip Doppler between device and lander Speed and round trip range finding, communicating in segmental arc with lander around device, round trip tests the speed, and to measure equation as follows:

${\mathrm{\δf}}_k=2\frac{f_0}{c}\left|\right|{\stackrel{\→}{v}}_{kr}\left|\right|=2\frac{f_0}{c}\sqrt{v_{rx\_k}^2+v_{ry\_k}^2+v_{rz\_k}^2}+w_f$

It is around device and lander relative radial rate, δ f_kFor frequency shift amount, f₀For fundamental frequency, c is the light velocity.w_fFor process Measurement noise.This process noise is included around device orbit error, atmosphere errors, base band Error, forwarding unit error and receiver Error etc..

Round trip range finding measurement equation is as follows:

$r=\frac{1}{2}{\mathrm{ct}}_r=\sqrt{{(x_i-x_0)}^2+{(y_i-y_0)}^2+{(z_i-z_0)}^2}+w_d$

Wherein: t_rFor total propagation time, (x_i,y_i,z_i) it is around device position, (x₀,y₀,z₀) it is lander position.w_dFor Process measurement noise.This process noise includes around device orbit error, atmosphere errors, time delay error, forwarding unit error and connecing Receive chance error difference etc..

Step 3: consider lander landing resting state after martian surface, lander state under Mars is connected coordinate system Equation is simple, x=[x₀,y₀,z₀], v=[0,0,0].

Step 4: obtain lander and after the round trip Doppler range rate measurement between device and range finding amount, using least square solution Calculate the position of lander, and by passing Cross-Link measurement data back auxiliary information that the earth positions as lander around device.

The measurement equation of the state equation according to step 3 and step 2, obtains lander position by method of least square, by It is nonlinear in measurement equation, linearisation is carried out by series expansion.

What the present invention was brought has the beneficial effect that:

A kind of Mars landing device static immobilization method based on cincture device disclosed by the invention, can be used for ancillary terrestrial and follows the tracks of Measurement, between making up due to ground fire, distance is remote, and ground, facing to the difficult larger shortcoming of tracking measurement of land device, makes full use of around device On-board equipment, does not increase extra cost, improves the utilization rate of on-board equipment.

Localization method of the present invention, is tested the speed ranging information by the radio around between device and lander, using round trip measurement Mode, launch wireless signal by around device, again by passing Cross-Link measurement data back ground around device after lander transparent forwarding Ball is processed, and for ancillary terrestrial tracking measurement, improves lander in areographic positional precision.

Brief description

The detailed description with reference to the following drawings, non-limiting example made by reading, the further feature of the present invention, Objects and advantages will become more apparent upon:

Fig. 1 is to position schematic diagram around device and ground control station to lander；

Fig. 2 is ground control station to around device vlbi instrumentation plan；

Fig. 3 is to resolve schematic diagram around device measurement data.

Specific embodiment

With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill to this area For personnel, without departing from the inventive concept of the premise, some changes and improvements can also be made.These broadly fall into the present invention Protection domain.

Mars landing device static immobilization method based on cincture device disclosed in this invention, when Mars landing device lands in fire Behind star catalogue face, introduce on the basis of ground control station is to lander tracking measurement around device as relay station, surveyed using round trip The mode of amount, obtains around device and lander relative position relation, and Cross-Link measurement data is passed back the earth as subsidiary, Improve lander in areographic positional precision.

Around device as relay station, adopt x band communication around between device and ground, adopt uhf frequency range to lead to and between lander Letter.

It is ground based radio navigation around the main tracking measurement mode of device and lander, the ground control station of China is main It is distributed in Beijing, Shanghai, Kunming and four, Urumchi place, by Shanghai as data processing centre, adopt to around device Vlbi measures.

The orbit parameter of cincture device is it is known that measured by ground control station；The position of cincture device and velocity accuracy are shadows simultaneously Ring the key factor of lander positional precision, higher around the position of device and velocity accuracy, the positioning precision of lander is higher.

Around device, lander is carried out with round trip to test the speed range finding, by cincture device electromagnetic signals, through transparent turn of lander After sending out, signal is passed back around device, is processed by passing signal back the earth around device.By the final acquisition of multi-turn measurement around device Lander positioning precision can reach more than ten kilometers.

As shown in FIG. 1 to 3, to implement step as follows for the present invention:

Step 1: determine around the communication segmental arc between device and lander, mainly consider both wireless communication distance ρ and two The observability of person's sight line.Take ρ ＜ 4000km；The position vector making lander to Mars barycenter isLander is to around device Position vector isAngle between the two is α it is contemplated that lander reception antenna has the restriction at 5 ° of elevations angle, then finally can lead to The condition of letter segmental arc is:

$\mathrm{\α}={\cos }^{-1}\left(\frac{{\stackrel{\→}{s}}_1\·{\stackrel{\→}{s}}_2}{\left|{\stackrel{\→}{s}}_1\right|\·\left|{\stackrel{\→}{s}}_1\right|}\right)\≤85$

It can be found that due to Mars rotation, there is relative motion around between device and lander, some number of turns can communicate segmental arc Long, some number of turns segmental arc that can communicate is short, does not even have the segmental arc that can communicate.

Step 2: known on the basis of device position and speed, set up and survey around the round trip Doppler between device and lander Speed and round trip range finding, communicating in segmental arc with lander around device, round trip tests the speed, and to measure equation as follows:

${\mathrm{\δf}}_k=2\frac{f_0}{c}\left|\right|{\stackrel{\→}{v}}_{kr}\left|\right|=2\frac{f_0}{c}\sqrt{v_{rx\_k}^2+v_{ry\_k}^2+v_{rz\_k}^2}+w_f$

It is around device and lander relative radial rate, δ f_kFor frequency shift amount, f₀For fundamental frequency, c is the light velocity.w_fFor process Measurement noise.This process noise is included around device orbit error, atmosphere errors, base band Error, forwarding unit error and receiver Error etc..Wherein in orbit error, three directions of site error are 1km/s, and velocity error is 1m/s, and base band Error is 10mhz, Because the propagation velocity of electromagnetic wave error that air causes is 828m/s.

Round trip range finding measurement equation is as follows:

$r=\frac{1}{2}{\mathrm{ct}}_r=\sqrt{{(x_i-x_0)}^2+{(y_i-y_0)}^2+{(z_i-z_0)}^2}+w_d$

Wherein: t_rFor total propagation time, (x_i,y_i,z_i) it is around device position, (x₀,y₀,z₀) it is lander position.w_dFor Process measurement noise.This process noise includes around device orbit error, atmosphere errors, time delay error, forwarding unit error and connecing Receive chance error difference etc..

Wherein in orbit error, three directions of site error are 1km/s, and velocity error is 1m/s, the electricity being caused due to air Electromagnetic wave propagation velocity error is 828m/s.

Step 3: consider lander landing resting state after martian surface, lander state under Mars is connected coordinate system Equation is simple, x=[x₀,y₀,z₀], v=[0,0,0].

Step 4: obtain lander and after the round trip Doppler range rate measurement between device and range finding amount, using least square solution Calculate the position of lander, and by passing Cross-Link measurement data back auxiliary information that the earth positions as lander around device.

According to step 2 with regard to testing the speed the source of ranging process noise and magnitude around device, as shown in table 1.

Tested the speed ranging information around device according to what step 2 obtained, using the linearisation of method of least square.With the information of testing the speed it is Example, observed quantity v_krWith quantity of stateBetween nonlinear observational equation, its linearisation is obtained:

${\hat{z}}_k=v_{kr}=h_k\stackrel{\→}{x_0}$

$h_k=\[\begin{array}{ccc}\frac{\∂{\hat{z}}_k}{\∂x_0}& \frac{\∂{\hat{z}}_k}{\∂y_0}& \frac{\∂{\hat{z}}_k}{\∂z_0}\end{array}\]$

Given lander location estimation initial valueUsing a series of relative radial rate iterated revision not recorded in the same time Initial value, finally gives the position coordinateses of lander.Define matrix b as follows:

$b_k=\[\begin{array}{cccc}{h}_1;& h_2;& ...;& h_m\end{array}\]={\left[\begin{array}{ccc}\frac{\∂{\hat{z}}_1}{\∂x_0}& \frac{\∂{\hat{z}}_1}{\∂y_0}& \frac{\∂{\hat{z}}_1}{\∂z_0}\\ \frac{\∂{\hat{z}}_2}{\∂x_0}& \frac{\∂{\hat{z}}_2}{\∂y_0}& \frac{\∂{\hat{z}}_2}{\∂z_0}\\ \mathrm{...}& \mathrm{...}& \mathrm{...}\\ \frac{\∂{\hat{z}}_m}{\∂x_0}& \frac{\∂{\hat{z}}_m}{\∂y_0}& \frac{\∂{\hat{z}}_m}{\∂z_0}\end{array}\right]}_{m\×3}$

It is assumed thatFor t_kThe radial velocity that moment iterated revision obtains and actual radial velocity difference, therefore:

$b_k{\mathrm{\δ\ρ}}_k=\mathrm{\δ}{\stackrel{\→}{v}}_{d\_k}$

${\mathrm{\δ\ρ}}_k={\left({b_k}^t{b}_k\right)}^{-1}{b_k}^t\mathrm{\δ}{\stackrel{\→}{v}}_{d\_k}$

Wherein: δ ρ_kRepresent t_kThe lander position correction amount based on least-squares calculation for the moment.Then t_k+1At the beginning of moment iteration It is worth and be:

${\stackrel{\→}{r}}_{k+1}={\stackrel{\→}{r}}_k-{\mathrm{\δ\ρ}}_k$

Next round iteration is carried out with this initial value, until δ ρ_k+1Tend in a small amount, finally converging on lander position coordinateses.

This example adopts method of least square to explain the position of lander, and positioning precision is finally around 2 circle measurements around device, Within positional precision is 20km.

Above the specific embodiment of the present invention is described.It is to be appreciated that the invention is not limited in above-mentioned Particular implementation, those skilled in the art can make a variety of changes within the scope of the claims or change, this not shadow Ring the flesh and blood of the present invention.In the case of not conflicting, feature in embodiments herein and embodiment can any phase Mutually combine.

Claims (7)

1. a kind of based on the Mars landing device static immobilization method around device it is characterised in that when Mars landing device lands in fire Behind star catalogue face, introduce on the basis of ground control station is to lander tracking measurement around device as relay station, surveyed using round trip The mode of amount, obtains around device and lander relative position relation, and Cross-Link measurement data is passed back the earth as subsidiary, Improve lander in areographic positional precision.

2. according to claim 1 a kind of based on the Mars landing device static immobilization method around device it is characterised in that institute State and adopt x band communication around between device and ground, adopt uhf band communication and between lander.

3. according to claim 1 a kind of based on the Mars landing device static immobilization method around device it is characterised in that institute State and be tracked measuring using ground based radio navigation mode around device and lander, adopt vlbi to measure to around device.

4. according to claim 1 a kind of based on the Mars landing device static immobilization method around device it is characterised in that ring Orbit parameter around device is measured by ground control station, and the positional precision of lander is determined by around the position of device and velocity accuracy, The position of lander and velocity accuracy are higher, and the positioning precision of lander is higher.

5. according to claim 1 a kind of based on the Mars landing device static immobilization method around device it is characterised in that ring Around device, lander is carried out with round trip to test the speed range finding, by around device electromagnetic signals, after lander transparent forwarding, signal passes Winding, around device, is processed by passing signal back the earth around device, by the multi-turn measurement final acquisition lander positioning around device Precision.

6. a kind of Mars landing device static immobilization method based on cincture device according to claim 5 is it is characterised in that have Body implementation method comprises the steps:

Step 1: determine around the communication segmental arc between device and lander, mainly consider that both wireless communication distance ρ regard with both The observability of line, wherein takes ρ ＜ 4000km；The position vector making lander to Mars barycenter isLander is to around device Position vector isAngle between the two is α, then the condition around the segmental arc that can communicate between device and lander is:

180-α≥90

There is the restriction at 5 ° of elevations angle in view of lander reception antenna, then the condition of the segmental arc that finally can communicate is:

$\mathrm{\α}={\cos }^{-1}\left(\frac{{\stackrel{\→}{s}}_1\·{\stackrel{\→}{s}}_2}{\left|{\stackrel{\→}{s}}_1\right|\·\left|{\stackrel{\→}{s}}_2\right|}\right)\≤85$

Step 2: known around device position and speed on the basis of, set up around the round trip Doppler range rate measurement between device and lander and Round trip is found range, and communicating in segmental arc with lander around device, round trip tests the speed, and to measure equation as follows:

${\mathrm{\δf}}_k=2\frac{f_0}{c}\left|\right|{\stackrel{\→}{v}}_{kr}\left|\right|=2\frac{f_0}{c}\sqrt{v_{rx\_k}^2+v_{ry\_k}^2+v_{rz\_k}^2}+w_f$

It is around device and lander relative radial rate, δ f_kFor frequency shift amount, f₀For fundamental frequency, c is the light velocity, w_fFor process measurement Noise, this process noise includes around device orbit error, atmosphere errors, base band Error, forwarding unit error and receiver error,

Round trip range finding measurement equation is as follows:

$r=\frac{1}{2}{\mathrm{ct}}_r=\sqrt{{(x_i-x_0)}^2+{(y_i-y_0)}^2+{(z_i-z_0)}^2}+w_d$

Wherein: t_rFor total propagation time, (x_i,y_i,z_i) it is around device position, (x₀,y₀,z₀) it is lander position, w_dFor process Measurement noise, this process noise is included around device orbit error, atmosphere errors, time delay error, forwarding unit error and receiver Error；

Step 3: consider lander landing resting state after martian surface, lander state equation under Mars is connected coordinate system Simply, x=[x₀,y₀,z₀], v=[0,0,0]；

Step 4: obtain lander and after the round trip Doppler range rate measurement between device and range finding amount, resolved using method of least square The position of land device, and by passing Cross-Link measurement data back auxiliary information that the earth positions as lander around device.

7. according to claim 6 a kind of based on the Mars landing device static immobilization method around device it is characterised in that institute The concrete methods of realizing stating step 4 is, the measurement equation of the state equation according to step 3 and step 2, is obtained by method of least square Take lander position, because measurement equation is nonlinear, linearisation is carried out by series expansion.