CN101893440B - Celestial autonomous navigation method based on star sensors - Google Patents

Abstract

The invention provides a celestial autonomous navigation method based on star sensors, which comprises the following steps: calculating attitude information based on a geocentric inertial coordinate system, which is output by a star sensor; calculating the optical axis direction based on the geocentric inertial coordinate system; converting the optical axis direction based on the geocentric inertial coordinate system into optical axis direction based on a WGS84 coordinate system; reading the included angles alpha 0 and beta 0 between the X and Y directions of the star sensor and the horizontal direction from a laser level meter; calculating the direction in the WGS84 coordinate system when the optical axis direction is perpendicular to the horizontal level; calculating the longitude alphaand latitude beta of the underground point S of the carrier; and outputting the attitude q and the longitude alpha and latitude beta of the underground point of the carrier in the geocentric inertialcoordinate system. The invention avoids measurement and control errors caused by horizontal reference platforms, enhances the measuring accuracy, and simultaneously outputs the attitude of three axesand the longitude and latitude of the carrier in the geographic coordinate system in real time, thereby completely realizing celestial autonomous navigation.

Description

Based Autonomous Navigation astronomical star sensor

(-) FIELD

[0001] The present invention relates to a celestial navigation technology, specifically an autonomous navigation method is based on the astronomical star sensor. (B) Background Art

[0002] In the late sixties early seventies, inertial technology began to be used a variety of surveying and mapping work. The United States developed the inertial positioning and orientation system, referred to as the PADS system. After orientation with an inertial positioning system ground car carrying a tortuous exercise distance, horizontal position accuracy is determined by the system is 20 m and a height of 10 meters rms error. This technology achievement is clearly of great significance for the application of inertial technology.

[0003] After the inertial positioning and orientation system successfully developed, the US Army has also developed the inertial positioning system anertial Position System, IPS system). Inertial positioning system developed in order to further improve the positioning accuracy on the basis of the inertial positioning and orientation system. Inertial Positioning System to determine the orientation of the finger is in gyrocompass on the basis of the North implemented by the theodolite, the system with the outside world any light, electrical contact does not occur. So good for hiding, working without restriction environmental conditions. It can provide initial alignment azimuth reference needs. However, the accuracy of the reference position determined by this method depends on the level of gyro and accelerometer, generally only up to a few minutes of arc, which would increase the position error accumulate over time. This meets the requirements for short-range navigation system; and long-distance navigation system can not meet the accuracy requirements. So simply relying on inertia to improve the accuracy of the instrument to improve positioning accuracy is very difficult.

[0004] The radio navigation system using radio guiding the aircraft along a predetermined route, at a predetermined time to reach the destination of navigation technology. A typical Loran navigation system A, C Loran, Omega, to the measuring instrument. These systems utilize radio wave propagation characteristics of the carrier can be measured navigation parameters (azimuth, distance and speed), and the deviation is calculated a predetermined route, so that a carrier eliminate the deviation to maintain the correct course. But the radio navigation system from a limited effect, there is blind service, remote navigation accuracy is low, and prone to attack, their application and development has been limited.

[0005] Modern satellite navigation as the primary means of navigation, greatly promoted the development of science and technology. The advantage is the propagation of radio waves essentially unaffected by ground meteorological factors, topography, and establishing stations are not subject to geographical constraints, distance is unlimited, so you can easily establish a global navigation system. However, a common feature is a particular satellite navigation beacon broadcasts the specific format of the navigation data at a particular frequency, its navigation signal extremely weak. "Sanding a weak" satellite navigation system determines the technical features of vulnerable and manipulation.

[0006] Global Positioning System (GlcAal Position System, GPS) is a space rendezvous point navigation system developed by the United States timing and ranging a way, the user can provide continuous global, real-time, high-accuracy three-dimensional position, three-dimensional velocity and time information.

[0007] However, the GPS signal is passed from space to the ground, it is not foolproof, or can be disturbed and destroyed. In "Operation Allied Force" in, GPS signal may have been unintentional interference US electronic warfare aircraft (such as the EA-6B) and unmanned jammer, the US military is trying to overcome this problem. This shows that as long as suitable measures can interfere with GPS systems to reduce the positioning accuracy, so dependent on GPS for navigation and positioning or guided weapons systems off course. Russia at the 1997 Moscow Air Show exhibit a GPS jammer, such interference function and GL0NASS GPS satellite signal interference, can inhibit the normal work within hundreds of kilometers receiver.

[0008] and with the reliance on GPS is growing, it is also bound to become increasingly worried about the GPS satellites under attack. GPS satellites did not take anti-nuclear and anti-reinforcing effect of laser weapons means of protection, there is no anti-collision detectors, nor the orbit maneuver capability. It is more vulnerable to attack, with the increase of its role, it will inevitably become a target of attack.

[0009] In addition GPS, the US military is controlled by its high military code encryption degree, it can not be used; although its public code available, but anti-interference ability; newly developed GPS satellites may have some areas off function. Thus the use of GPS by the US constrained.

[0010] is an important member celestial navigation star sensor. Star sensor as a high precision attitude sensor, it is widely used in a variety of spacecraft. Compared with other inertial navigation and GPS satellite navigation, etc., it has many advantages, such as high precision, require long terrestrial positioning orientation; Also, star sensor has the advantage of GPS navigation do not have immunity is concerned. Thus most researchers currently use drift correction parameters using astronomical goniometric Gyroscope; or information provided by the INS inertial navigation systems, GPS location or to provide position and velocity information celestial navigation (star sensor) providing attitude information, this information simple combinations obtained by combining the navigation information to a navigation system. However, these systems pose information using only the precision of the output star sensor, an inertial navigation only calibration equipment, it is not used as an independent means of navigation.

[0011] In order to take full advantage of precision star sensor information. Many scholars inertial device provides a horizontal reference astronomical autonomous positioning is achieved, due to limitations and restrictions inertia apparatus control method of the platform member, it is difficult to control the dynamic internet reference level completely, thereby reducing the accuracy of the reference level. The horizontal reference navigation error reduction results in reduced accuracy. This is incompatible with the objective requirements of high-precision navigation. Subject to the level of the reference limit celestial navigation has become a bottleneck to the development of precision.

[0012] In recent years, there have been stars based on star sensor refraction autonomous navigation. The navigation basic principle is as follows: while observing two stars on the star sensor, a star of stars is much greater than the height of the height of the atmosphere, the stars were not refracted, another star of the stars by atmospheric refraction, so that two beams of starlight will be different from the angle between the nominal value, the amount of change of this angle is the pitch angle of refraction starlight. Starlight use the angle of refraction and atmospheric density relationships and atmospheric density varies with height also have an existing mathematical model to determine the height of the stars in the atmosphere, this reflects the high degree of geometric relationship between the carrier and the Earth. This navigation claim atmospheric density variation with height of more precise mathematical model. However, affected by factors affecting the atmosphere, seasonal changes and climate, the atmosphere is difficult to establish a more precise mathematical model internationally. The navigation method and the use of part of the field of view must starlight sun through the atmosphere, there is a deviation caused by these stars in the star position of the image plane of the sensor, thereby reducing the output of the posture of the star sensor.

(Iii) Disclosure of the Invention

[0013] The object of the present invention is to provide a real-time three-axis attitude output, autonomous navigation method based on the astronomical star sensor in real-time output vector geographic latitude and longitude coordinate system.

[0014] The object of the present invention is implemented: the autonomous navigation method based on the astronomical star sensor, the following steps:

[0015] Step a: star sensor output is calculated based on the posture information of the geocentric inertial coordinate system;

[0016] Step Two: an optical axis based on the geocentric inertial coordinate point calculated posture information;

[0017] Step three: the optical axis based on the geocentric inertial coordinate system based on the optical axis point to point converted in WGS84 coordinates; star sensor reading angle X and Y directions in the horizontal direction from the laser level instrument and β.

[0018] Step Four: pointing vertically in WGS84 coordinate system is calculated according to a horizontal axis pointing in α Q and β Q;

[0019] Step Five: Underground vector calculating the point S latitude and longitude α β; [0020] Step Six: the output vector coordinates in the geocentric inertial attitude q and underground longitude and latitude α β.

[0021] The present invention is an autonomous navigation method based on the astronomical star sensor, a photoelectric sensor to measure the carrier platform (i.e. celestial navigation system platform) and the horizontal angle, which avoids the reference error level measurement and control of the platform brings due, thereby improve the measurement accuracy. While the real-time output three-axis attitude, but also be able to support real-time output latitude and longitude in the geographic coordinate system, so that the full realization of astronomical autonomous navigation.

(Iv) Brief Description of Drawings

[0022] FIG. 1 is schematic diagram of the system of the present invention;

[0023] FIG 2 is a flowchart of astronomical autonomous navigation based on a star sensor of the present invention;

A star type satellite sensor waveform diagram showing the test results using [0024] FIG. 3 of the present invention;

Continuous output triaxial goniometer angle and attitude calculation device according to star sensor local longitude and latitude errors [0025] FIG. 4 of the present invention;

[0026] The working flow diagram of FIG. 5 of the present invention is applied to a carrier;

[0027] FIG. 6 is a schematic view of the present invention is applied to a carrier, Os-XsYJs: star sensor image space coordinates, Os' -Xs' Ys, Zs': translation star sensor image space coordinate system, wherein 0 / Os projected point is a point on the ground surface, OhXhYhZh: to 0S 'level as the origin of a coordinate system.

(E) Detailed Description

[0028] conjunction with the accompanying drawings illustrative of the present invention will be further described.

[0029] Example 1: in conjunction with FIG. 1, FIG. 2 of the present invention an autonomous navigation method based on the astronomical star sensor, the following steps:

[0030] Step a: star sensor output is calculated based on the posture information of the geocentric inertial coordinate system;

[0031] Step Two: an optical axis based on the geocentric inertial coordinate point calculated posture information;

[0032] Step three: the optical axis based on the geocentric inertial coordinate system based on the optical axis point to point converted in WGS84 coordinates; star sensor reading angle X and Y directions in the horizontal direction from the laser level instrument and β.

[0033] Step Four: pointing vertically in WGS84 coordinate system is calculated according to a horizontal axis pointing in α Q and β Q;

[0034] Step Five: α is calculated longitude and latitude of the point S subterranean β carrier;

[0035] Step Six: the output vector coordinates in the geocentric inertial attitude q and underground longitude and latitude α β.

[0036] Example 2: in conjunction with Figures 1-4, celestial navigation system to realize autonomous navigation, the main problem is: to provide a horizontal reference rid constraints and requirements of the carrier device by the inertial navigation information measured physical quantity. Thus, to get rid of the constraints of the reference level, while seeking to measure the physical carrier of navigation information, it is to achieve high-precision astronomical navigation inevitable. Object of the present invention are: to establish autonomous navigation system based astronomical star sensor. The system shown in Figure 1. Each coordinate system is defined as follows:

[0037] geocentric inertial coordinate system Otl-Kyc ^: coordinate origin Otl Earth center of mass, X0 axis points Ttl time mean equinox, ZTL axis pointing flat Ttl time pole, Y0 axis in the flat equatorial plane Ttl time, east composition right-handed. Often used in Bessel (Bessel years, called a false or years. Regression of flat longitudinal length, i.e., 365.2421988 mean solar day. Bessel common epoch mean longitude of the sun is equal to 0 Viewpoint moments, such as 1950.0, not 1950 at 0:00 on January 1, but December 31, 1949 22 09 minutes 2 seconds) as the first Τ. , E.g. pine Schmid catalog (Smi thsonian AstrophysicalObservatory Star Catalog) using 2000. ◦ as TQ, called epochs 2000.0 (abbreviated J2000. 0). The program uses J2000. 0 inertial coordinate system.

[0038] WGS-84 coordinate system 0w_Xwywzw coordinate origin Ow of geocenter which Zw axis geocentric spatial rectangular coordinate system point BIH (International time) 1984.0 protocol defined earth electrode (CTP) direction, Xw-axis pointing BIH 1984 zero meridian plane 0 and the intersection of the equator CTP, yw axis and Zw axis, Xw axis perpendicular right-handed configuration;

[0039] The geographic coordinate system (coordinate system Northeast days) 0eieyeze: Oe coordinate origin of the moving object and the center of the earth connection with the (projected point on a moving body or take the Earth's surface) the intersection of the Earth's surface, ^ east axis pointing in the local horizontal plane , North axis points in the local horizontal plane along the axis of the local% vertical direction and directed to zenith. A ground plane or a horizontal plane;

[0040] The star sensor image space coordinates 0sisyszs = Os star sensor as the image plane center, xs, ys, respectively parallel to the two axes of the image plane coordinates, xs> ys> Zs constituting right-hand rule.

[0041] The set point vector S subterranean longitude a (0 <a <23i;. I0 <a <Ji when longitude, when π≤a <271 west longitude same applies hereinafter) and latitude β (-JI / 2≤ β <JI / 2; when -JI / 2≤β <0 when latitude when 0≤β <π / 2 latitude same applies hereinafter). Then in S direction WGS-84 coordinate system vector:

[0042]

[0043] Recognition of the star sensor and a laser level measuring means results are measured according to two star sensor image plane angle and the axis Xs [the horizontal direction, respectively a C1 and β 0. The mathematical model to calculate the direction of the carrier in the WGS-84 coordinate system vector, and then in accordance with

[0044] (1) to determine the longitude and latitude α β support point S of the ground surface, thereby realizing the positioning of the carrier. Therefore, while the output of the system carrier posture, but also the output position of the carrier.

[0045] The present invention provides a method for autonomous navigation based on the astronomical star sensor, the following major elements:

[0046] For the same reference coordinate system, since the carrier (generally of an aircraft) is uniquely determined attitude, attitude parameters reflected in the physical quantity is described with reference to the coordinate axis, it referred to attitude parameters, in many forms. The most general attitude parameters are the body axis direction between the coordinate axes and the reference cosine Α.

[0047] According to the definition of the direction cosine of the direction vector geometric coordinates in the reference coordinate system can be determined as: [0048]

[0049] where the subscripts o, 0 represents a vector coordinate system and the reference coordinate system,

[0050]

[0051] The problem of determining three-axis attitude in the carrier, since the matrix A completely determined state vector in the reference coordinate system, so that the direction cosine matrix A is a matrix posture.

[0052] The interchangeable between various forms of pose parameters. Direction cosine matrix A and thus may be expressed as:

[0053]

[0054] wherein posture information q = qii + q2j + q3k + q4, a star sensor in the geocentric inertial coordinate system.

[0055] Therefore, the optical axis star sensor pointing at the geocentric inertial coordinate system. Unit vector: [0056]

[0057] Calculation axis star sensor pointing vector in the WGS84 coordinate system: [0058]

[0059] wherein [the ER] Earth's rotation matrix is ​​expressed as:

[0060] [ER] = Rz (eg) (7) [0061] where Rz of (ez) around the Z axis represents the coordinate transformation matrix ez rotation angle. [0062]

[0063] eg (unit: rad) is the true star inch, can be expressed as: [0064]

[0065] g is flat ecliptic, is calculated as: [0066]

[0067] Tu is slightly centuries of Confucianism starting from 2000.0. Expressed as follows; [0068]

[0069] JD (t) represents the time t is calculated corresponding to Julian days.

[0070] Og (unit: radian) Greenwich mean sidereal inch, calculated as follows: [0071]

[0072] [0073] A £, AV are longitude and obliquity nutation nutation. Calculation expression as follows: [0074]

[0075] [0076] where Ai, A '^ BijB' ^ kij is a constant, can be found in Chapter IAU1980 movable Sequence Listing. t is the time vector.

[0077] The angle between the vector and then the two horizontal axes, respectively a. And Ptl, calculated perpendicular to the horizontal axis vector pointing in WGS84 coordinate system: [0078]

[0079] wherein Rx (Ptl) 3 represents the rotation around the X axis. Angular coordinate transformation matrix. That is: [0080]

[0081] Rv (a0) represented by coordinate transformation matrix around the y axis rotation angle a ^. which is

[0082]

[0083] According ^ j, +, we can calculate the longitude and latitude β α S carrier the surface points.

[0084] The main performance indicators:

[0085] We use a certain type of satellite star sensor as the posture of the output member celestial navigation system (Table Quaternion q = q (1 * i + qi * j + q2 * k + q3), using XXX types of laser horizontal angle member star sensor to measure the angle between the X-axis and Y-axis in the horizontal direction.

[0086] Since the star sensor may be directly output three-axis attitude vector, star sensor system itself determines the accuracy and reliability of the posture, the navigation apparatus using a model field experiments were carried out at some stations. These results were calculated using the latitude and longitude of the local surface, in order to verify the feasibility and reliability of these data, to be placed in any of the navigation system, after a long run, save test data. In a second experiment consecutive stations 1046, by analysis, the navigation system accuracy in longitudinal and latitudinal directions were 0. 9637281519 "(3 σ) and 1. 3609644735〃 (3 σ).

[0087] Example 3: in conjunction with FIG. 5, FIG. 6, the present invention is an autonomous navigation method based on the astronomical star sensor, comprising three subsystems: star sensor system and two laser level measurement system. Three-axis attitude of the main carrier star sensor; two laser measuring system measuring the angle between the major axis and two horizontal carriers.

[0088] Working procedure: stars by star sensor optical lens, an imaging in the image plane star sensors (such as the APS or C⑶), the imaging circuit electrical signals into the image plane of a complete star chart, and save in a memory; star chart image extracting software reads data in the memory, and extracts from the image the coordinates of the star chart; day star pattern recognition software uses ball recognition algorithm in accordance with the table information stored in the satellite's star sensor, for these stars image coordinate recognition performed (if the star sensor has a priori information, star pattern identification software uses satellite tracking algorithm); pose calculation software using the corresponding pose calculation algorithm and the recognition result, and the star identification based on these results, and the use has identification observed star, star sensor orientation information calculated in the q geocentric inertial coordinate system. Laser level measuring means were measured two star sensor according to the angle of the image plane axis in the horizontal direction, a horizontal plane perpendicular to the optical axis is calculated in the vector pointing WGS84 coordinate system. And outputs the pose information and the star sensor vector in the geocentric inertial coordinate system. This information is autonomous navigation information.

[0089] The autonomous navigation method based on the astronomical star sensor proposed by the present invention is the recognition result of the star sensor may be calculated to the satellite sensor Os-h in the earth's axis vector of the inertial coordinate system by coordinate transformation ,, i.e. available under the direction WGS-84 coordinate system vector lack "using two laser level measuring member were measured as the angle between the star sensor plane axes Xs and ys are the horizontal direction and ^ ^^. direction vector the shaft and are wound xs ys axis and a ^ β C1 direction vector angle after < '3 is a vector in the direction of the WGS-84 coordinate system, and then into (1) to obtain the vector of the surface point S longitude and latitude α β, in order to achieve positioning of the carrier. Therefore, not only the navigation system outputting three-axis attitude vector, and the output position of the carrier. In order to achieve astronomical autonomous navigation.

Claims (1)

CLAIMS 1. A method for autonomous navigation based on the astronomical star sensor, characterized in that: the following steps: Step 1: calculate the star sensor output of the posture information based on the geocentric inertial coordinate system; Step two: The posture information calculated based on the geocentric inertial the optical axis of the coordinate system point; step three: the optical axis based on the geocentric inertial coordinate system is converted into points on the optical axis in the WGS84 coordinate point; star sensor reading laser level from the image plane of the two axes the angle between the horizontal direction and ^ tl; step four: calculating a horizontal axis pointing in accordance α Q and β Q pointing vertically when in WGS84 coordinate system; step five: calculated longitude and latitude beta] [alpha] vector subsurface point S; step six: output vector coordinates in the geocentric inertial attitude q and underground longitude and latitude α β.