CN103234538A - Autonomous navigation method for planet in final approaching section - Google Patents

Abstract

The invention relates to an autonomous navigation method for a planet in a final approaching section, which belongs to the field of deep space exploration. The method comprises the following steps: establishing a state model of the planet in the final approaching section; carrying out radio measurement and communication through a detector and planetary orbiters determined by n positions, observing m pulsars and establishing an autonomous navigation measurement model of the planet in the final approaching section; and calculating the state of the detector through navigation filtering based on the two models. According to the invention, measurement characteristics of pulsar navigation and radio navigation are combined in the autonomous navigation method, a non-linear filtering method is employed, so autonomous navigation of the planet in the final approaching section is realized, precision and instantaneity of autonomous navigation of the planet in the final approaching section are improved, and the autonomous navigation method has good exploitativeness and high measurement precision and can satisfy the requirement for instantaneity of autonomous navigation.

Description

A kind of planet finally approaches the section autonomous navigation method

Technical field

The present invention relates to a kind of planet and finally approach the section autonomous navigation method, belong to the survey of deep space technical field.

Background technology

In order to obtain more valuable science material, need planetary probe to land to having the specific region of higher scientific value.By planet enter, the advanced independent navigation guidance of decline, landing mission can effectively improve the planetary landing precision with control technology, but for the atmosphere planet is arranged, planet gets the hang of, and particularly definite precision of flight-path angle remains influences the atmosphere accuracy factors of catching and land.Finally approach section independent navigation scheme to guarantee the planetary landing precision so be badly in need of making up planet.

The detection mission of Mars of successfully having landed finally approaches section at Mars and depends on ground deep space net measured radial distance and velocity information mostly and navigate." curious number " task of implementing has added Δ DOR on this basis to be measured, and has effectively improved approaching section navigation accuracy.But because ground fire distance is far away, often be subjected to the influence of communication delay based on the navigation scheme of ground deep space net, be subjected to the constraint of visible segmental arc in addition, be difficult to satisfy a final requirement that approaches section independent navigation real-time.

There is the scholar to propose to utilize the exactly determined planetary orbit device in position, communicates by letter and enrich detector and finally approach the navigation information of section at planet with carrying out radio survey between the detector, effectively improve navigation accuracy.But planetary orbit device limited amount is difficult to still guarantee that detector finally approaches the real-time independent navigation of the overall process of section at present.

Summary of the invention

The present invention is directed to planet and finally approach section independent navigation problem, propose a kind of planet and finally approach the section autonomous navigation method, in conjunction with pulsar navigation and radionavigational measurement characteristics, adopt non-linear filtering method, realize that planet finally approaches the section independent navigation, improves precision and real-time that planet finally approaches the section independent navigation.

Planet finally approaches the section autonomous navigation method and specifically comprises the steps:

Step 1: set up planet and finally approach the section state model

Under day heart inertial coordinates system, set up the detector's status model.The state vector of detector is position vector r _s=[r _x, r _y, r _z] ^TWith velocity v _s=[v _x, v _y, v _z] ^TConsider solar gravitation, planetary gravitation and other perturbative forces, the state model of setting up planet approach section detector is:

$\stackrel{\·}{X}=\left[\begin{array}{c}{\stackrel{\·}{r}}_s\\ {\stackrel{\·}{v}}_s\end{array}\right]=\left[\begin{array}{c}{v}_s\\ -{\mathrm{\μ}}_S\frac{r_s}{r_s^3}-{\mathrm{\μ}}_M(\frac{r_{\mathrm{Ms}}}{r_{\mathrm{Ms}}^3}-\frac{r_M}{r_M^3})+a\end{array}\right]---\left(1\right)$

μ wherein _SAnd μ _MBe respectively the gravitational constant of the sun and planet, r _MBe the position vector of planet, a is other not modeling perturbative force vectors, r _MsBe the position vector of detector with respect to planet, satisfy:

r _Ms=r _s-r _M （2）

The kinetic model of planet approach section detector is described as

Wherein

Step 2: set up planet and finally approach section independent navigation measurement model

The planetary orbit device of determining by detector and n position carries out radio survey and communicate by letter (radio adopts UHF wave band or X-band), obtains relative distance and relative velocity between detector and each planetary orbit device:

R _i=|r _s-r _mi|

$V_i=\frac{(v_s-v_{\mathrm{mi}})\·(r_s-r_{\mathrm{mi}})}{|r_s-r_{\mathrm{mi}}|}$ i=1,2,...,n （3）

R in the formula _iWith V _iBe respectively detector and arrive wherein relative distance and the relative velocity of i planetary orbit device, r _Mi=[r _Xmi, r _Ymi, r _Zmi] ^T, v _Mi=[v _Xmi, v _Ymi, v _Zmi] ^TBe respectively position vector and the velocity of i planetary orbit device, n is the number of orbiter, orbital vehicle.

Described planetary orbit device all is equipped with radio receiver-transmitter.

The X ray of received pulse star emission, and compare with the reference waveform that obtains by the ground long-term observation, obtain X ray and arrive detector and the mistiming that arrives solar system barycenter SSB:

${\mathrm{\Δt}}_j=t_{\mathrm{bj}}-t_{\mathrm{sj}}=\frac{n_j\·r_b}{c}+\frac{1}{2c{D}_{0j}}[{(n_j\·r_b)}^2-{r_b}^2+2(n_j\·b)(n_j\·r_b)$

$-2(b\·r_b)]+\frac{2{\mathrm{\μ}}_s}{c^3}\ln |\frac{n_j\·r_b+r_b}{n_j\·b+b}+1|$ （4）

j=1,2,...,m

C is the light velocity in the formula, n _jBe the unit vector of solar system barycenter SSB to j pulsar, the position vector that b is SSB under day heart inertial coordinates system, r _bBe the position vector of the relative SSB of detector, satisfy:

r _s=b+r _b （5）

D in addition _0jBe the distance that j pulsar arrives day heart, m is used pulsar quantity, in order to guarantee orbit determination accuracy, generally gets m 〉=3.

Because solar mass accounts for more than 99% of solar system quality, and pulsar is very remote apart from the solar system usually, (4) formula can be reduced to:

${\mathrm{\Δt}}_j=\frac{n_j\·r_s}{c}+{\mathrm{\ϵ}}_j---\left(6\right)$

ε in the formula _jMeasuring error for Gaussian distributed.By the combination of wireless measurement information and pulsar metrical information, the structure planet finally approaches a section independent navigation measurement model and is

y=[R _i,V _i,△t _j] ^T=h(x),

i=1,2,...,n, j=1,2,...,m

Step 3: independent navigation filtering is resolved

Finally approach the section state model according to planet And measurement model y=h (x), by navigation filtering calculating detector's status is estimated.Because it is non-linear that state model and measurement model all present, so select nonlinear filter for use, as UKF, set Kalman wave filter (EnKF) etc. improve navigation filtering accuracy and speed of convergence.Final output detector status information.

Beneficial effect

(1) the radio survey information of the relative planetary orbit device of employing, exploitativeness is strong, the measuring accuracy height.

(2) adopt the pulsar metrical information, satisfied the real-time requirement of independent navigation.

(3) utilize the nonlinear filter filtering of navigating to resolve, improved navigation precision of filtering and speed of convergence.

Description of drawings

Fig. 1 is the process flow diagram of the inventive method;

Fig. 2 is that Mars finally approaches a section independent navigation error result in the embodiment, a) is x shaft position error wherein; B) be y shaft position error; C) be z shaft position error; D) be x axle velocity error; E) be y axle velocity error; F) be z axle velocity error.

Embodiment

The independent navigation scheme that this example is finally measured in radio survey and pulsar near segment base at Mars, adopt the radio distance-measuring information between detector and three the Mars orbiter, orbital vehicles, and to three pulsar metrical informations, carry out filtering in conjunction with set Kalman wave filter and resolve independent navigation when realizing high-precision real.The specific implementation method of this example is as follows:

Step 1: Mars finally approaches the section state model and sets up

Under day heart inertial coordinates system, set up the detector's status model.The state vector of detector is position vector r _s=[r _x, r _y, r _z] ^TWith velocity v _s=[v _x, v _y, v _z] ^TConsider solar gravitation, Mars gravitation and other perturbative forces, the state model of Mars approach section detector is established as:

$\stackrel{\·}{X}=\left[\begin{array}{c}{\stackrel{\·}{r}}_s\\ {\stackrel{\·}{v}}_s\end{array}\right]=\left[\begin{array}{c}{v}_s\\ -{\mathrm{\μ}}_S\frac{r_s}{r_s^3}-{\mathrm{\μ}}_M(\frac{r_{\mathrm{Ms}}}{r_{\mathrm{Ms}}^3}-\frac{r_M}{r_M^3})+a\end{array}\right]---\left(1\right)$

μ wherein _SAnd μ _MBe respectively the gravitational constant of the sun and Mars, r _MBe the position vector of Mars, a is other not modeling perturbative force vectors.R in addition _MsBe the position vector of detector with respect to Mars, satisfy:

r _Ms=r _s-r _M （2）

And then the kinetic model of Mars approach section detector can be described as

Wherein

Step 2: Mars finally approaches section independent navigation measurement model and sets up

Radio survey and communicate by letter (the considering that omni-directional adopts the UHF wave band) of the Mars orbiter, orbital vehicle of determining by detector and a position can obtain relative distance and relative velocity between detector and the Mars orbiter, orbital vehicle:

R ₁=|r _s-r _m1|

$V_1=\frac{(v_s-v_{m1})\·(r_s-r_{m1})}{|r_s-r_{m1}|}$ （3）

R in the formula ₁With V ₁Be respectively detector to relative distance and the relative velocity of Mars orbiter, orbital vehicle,

r _Mi=[r _Xmi, r _Ymi, r _Zmi] ^T, v _M1=[v _Xm1, v _Ym1, v _Zm1] ^TBe respectively position vector and the velocity of Mars orbiter, orbital vehicle.

Described planetary orbit device is equipped with radio receiver-transmitter.

The X ray of received pulse star emission, and compare with the reference waveform that obtains by the ground long-term observation, obtain X ray and arrive detector and the mistiming that arrives solar system barycenter SSB:

${\mathrm{\Δt}}_j=t_{\mathrm{bj}}-t_{\mathrm{sj}}=\frac{n_j\·r_b}{c}+\frac{1}{2c{D}_{0j}}[{(n_j\·r_b)}^2-{r_b}^2+2(n_j\·b)(n_j\·r_b)$

$-2(b\·r_b)]+\frac{2{\mathrm{\μ}}_s}{c^3}\ln |\frac{n_j\·r_b+r_b}{n_j\·b+b}+1|$ （4）

j=1,2,m

C is the light velocity in the formula, n _jBe the unit vector of solar system barycenter SSB to j pulsar, the position vector that b is SSB under day heart inertial coordinates system, r _bBe the position vector of the relative SSB of detector, satisfy:

r _s=b+r _b （5）

D in addition _0jBe that j pulsar is to the distance of day heart.In order to guarantee orbit determination accuracy, present embodiment is got m=3.

Because solar mass accounts for more than 99% of solar system quality, and pulsar is very remote apart from the solar system usually, so (4) formula is reduced to:

${\mathrm{\Δt}}_j=\frac{n_j\·r_s}{c}+{\mathrm{\ϵ}}_j---\left(6\right)$

ε in the formula _jMeasuring error for Gaussian distributed.By the combination of wireless measurement information and pulsar metrical information, can make up Mars and finally approach a section independent navigation measurement model and be

y=[R ₁,V ₁,△t _j] ^T=h(x),

j=1,2,3

Step 3: independent navigation filtering is resolved

Finally approach the section state model according to Mars

And measurement model y=h (x), calculate and can estimate detector's status by navigation filtering.Because it is non-linear that state model and measurement model all present, so select for use set Kalman wave filter (EnKF) to improve navigation filtering accuracy and speed of convergence.Final output detector status information.

Enter preceding 12 hours independent navigation schemes at martian atmosphere and carry out mathematical simulation, enter preceding 6 hours ground deep space net radio tracking data and cut off, rely on subsequently with radio survey data and the pulsar measurement data of orbiter, orbital vehicle and carry out independent navigation.Mars finally approaches section independent navigation scheme performance as shown in Figure 2.Wherein scheme a), b), c) show x, y, z shaft position error respectively; Figure d), f e)) show x, y, z axle velocity error respectively.Related navigation scheme compares that navigation scheme navigation error based on ground deep space net radio tracking is littler, speed of convergence is faster, real-time is stronger.

Claims (3)

1. a planet finally approaches the section autonomous navigation method, it is characterized in that: specifically comprise the steps:

Step 1: set up planet and finally approach the section state model;

Under day heart inertial coordinates system, set up the detector's status model; The state vector of detector is position vector r _s=[r _x, r _y, r _z] ^TWith velocity v _s=[v _x, v _y, v _z] ^TConsider solar gravitation, planetary gravitation and other perturbative forces, the state model of setting up planet approach section detector is:

$\stackrel{\·}{X}=\left[\begin{array}{c}{\stackrel{\·}{r}}_s\\ {\stackrel{\·}{v}}_s\end{array}\right]=\left[\begin{array}{c}{v}_s\\ -{\mathrm{\μ}}_S\frac{r_s}{r_s^3}-{\mathrm{\μ}}_M(\frac{r_{\mathrm{Ms}}}{r_{\mathrm{Ms}}^3}-\frac{r_M}{r_M^3})+a\end{array}\right]---\left(1\right)$

μ wherein _SAnd μ _MBe respectively the gravitational constant of the sun and planet, r _MBe the position vector of planet, a is other not modeling perturbative force vectors, r _MsBe the position vector of detector with respect to planet, satisfy:

r _Ms=r _s-r _M （2）

The kinetic model of planet approach section detector is described as

Wherein

Step 2: set up planet and finally approach section independent navigation measurement model;

The planetary orbit device of determining by detector and n position carries out radio survey and communicates by letter, and obtains relative distance and relative velocity between detector and each planetary orbit device:

R _i=|r _s-r _mi|

$V_i=\frac{(v_s-v_{\mathrm{mi}})\·(r_s-r_{\mathrm{mi}})}{|r_s-r_{\mathrm{mi}}|}$ i=1,2,...,n （3）

R in the formula _iWith V _iBe respectively detector and arrive wherein relative distance and the relative velocity of i planetary orbit device, r _Mi=[r _Xmi, r _Ymi, r _Zmi] ^T, v _Mi=[v _Xmi, v _Ymi, v _Zmi] ^TBe respectively position vector and the velocity of i planetary orbit device, n is the number of orbiter, orbital vehicle;

The X ray of received pulse star emission, and compare with the reference waveform that obtains by the ground long-term observation, obtain X ray and arrive detector and the mistiming that arrives solar system barycenter SSB:

${\mathrm{\Δt}}_j=t_{\mathrm{bj}}-t_{\mathrm{sj}}=\frac{n_j\·r_b}{c}+\frac{1}{2c{D}_{0j}}[{(n_j\·r_b)}^2-{r_b}^2+2(n_j\·b)(n_j\·r_b)$

$-2(b\·r_b)]+\frac{2{\mathrm{\μ}}_s}{c^3}\ln |\frac{n_j\·r_b+r_b}{n_j\·b+b}+1|$ （4）

j=1,2,...,m

C is the light velocity in the formula, n _jBe the unit vector of solar system barycenter SSB to j pulsar, the position vector that b is SSB under day heart inertial coordinates system, r _bBe the position vector of the relative SSB of detector, satisfy:

r _s=b+r _b （5）

Wherein, D _0jBe the distance that j pulsar arrives day heart, m is used pulsar quantity;

(4) formula is reduced to:

${\mathrm{\Δt}}_j=\frac{n_j\·r_s}{c}+{\mathrm{\ϵ}}_j---\left(6\right)$

ε in the formula _jMeasuring error for Gaussian distributed; By the combination of wireless measurement information and pulsar metrical information, the structure planet finally approaches a section independent navigation measurement model and is

y=[R _i,V _i,△t _j] ^T=h(x),

i=1,2,...,n, j=1,2,...,m

Step 3: independent navigation filtering is resolved;

Finally approach the section state model according to planet

And measurement model y=h (x), select for use nonlinear filter to improve navigation filtering accuracy and speed of convergence, calculate by navigation filtering detector's status is estimated; Final output detector status information.

2. a kind of planet according to claim 1 finally approaches the section autonomous navigation method, it is characterized in that: radio adopts UHF wave band or X-band.

3. a kind of planet according to claim 1 finally approaches the section autonomous navigation method, it is characterized in that: m 〉=3.

Images