Summary of the invention
Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, a kind of small size, high integration, high precision, high reliability are provided, be applicable to the performance-oriented attitude determination system based on multi-sensor of fine resolution earth observation maneuvering satellite.
Technical solution of the present invention is: a kind of attitude determination system based on multi-sensor comprises responsive subsystem, acquisition of signal and preprocessing subsystem, comprehensive treatment subsystem; Described responsive subsystem is integrated star sensing probe, sun sensing probe, fiber optic gyro and three-axle magnetic field this four classes sensing unit of popping one's head in, its culminant star sensing probe and sun sensing probe are realized respectively the sensitivity to starlight information and sunshine information, convert starlight information and sunshine information to corresponding electric signal and follow and amplify; During installation, the responsive optical axis included angle of star sensing probe and sun sensing probe is 90 degree; Fiber optic gyro is finished the sensitivity to inertia information on three mutually perpendicular directions, and converts thereof into corresponding electric signal; The three-axle magnetic field probe is finished the sensitivity to Geomagnetism Information on three mutually perpendicular directions, and converts thereof into corresponding electric signal; Starlight information, sunshine information, Geomagnetism Information and inertia information are sent into acquisition of signal and preprocessing subsystem together; Acquisition of signal and preprocessing subsystem control are sent into the comprehensive treatment subsystem after above-mentioned four kinds of information are carried out level and smooth and pretreatment; Level and smooth and the pretreated starlight information of the warp that the comprehensive treatment subsystem will receive, sunshine information, Geomagnetism Information and inertia information are processed synchronously, adopt the integrated attitude determination method based on ant group particle filter algorithm, realize that the attitude of system is determined.
Acquisition of signal and preprocessing subsystem comprise A/D modular converter, fpga chip, configuring chip, SRAM or SDRAM memory device, clock circuit and power module, wherein A/D modular converter and fpga chip will convert digital signal to from the starlight information that responsive subsystem transmits, finish the pretreatment operation such as star chart denoising, distortion correction, barycenter extraction of star chart data, and level and smooth to sunshine information, Geomagnetism Information and inertia information, and the result after will processing sends in the comprehensive treatment subsystem; Clock circuit provides clock signal for fpga chip, and configuring chip is fpga chip storing software program, and SRAM or SDRAM memory device provide storage space for fpga chip, and power module provides power supply for acquisition of signal and preprocessing subsystem.
The comprehensive treatment subsystem comprises level shifter interface circuit, DSP or arm processor chip, extends out the Flash memory device, SRAM or SDRAM memory device, power module, clock circuit and serial ports expansion module, wherein level shifter interface circuit, DSP or ARM chip and serial ports expansion module receive the data from acquisition of signal and preprocessing subsystem, finish importance in star map recognition and starlight information is resolved, and appearance is decided in the fusion of associating sunshine information, Geomagnetism Information and the integrated attitude determination system of inertia information realization; Clock circuit provides clock signal for DSP or ARM chip, and extending out the Flash memory device is DSP or ARM chip-stored software program, and SRAM or SDRAM memory device provide data space for DSP or ARM chip, and power module provides power supply for the comprehensive treatment subsystem.
Integrated attitude determination method based on ant group particle filter algorithm, the starlight information that CMOS star sensing probe sensitivity is arrived, sunshine information in conjunction with the observation of sun sensing probe, the responsive Geomagnetism Information of three-axle magnetic field probe, and the inertia information that provides of the fiber optic gyro after error compensation, adopt optimum REQUEST algorithm, resolve and obtain the q battle array as the observation information of ant group particle filter; This observation information is further combined with the inertia information through error compensation, by ant group particle filter algorithm, the attitude and the gyro wander that obtain integrated attitude determination system are estimated, output with the compensation gyro, resolved at last the attitude parameter of integrated attitude determination system by attitude quaternion, finish the integrated attitude determination of integrated attitude determination system.
Principle of the present invention is: utilize star sensor, sun sensor, three axis magnetometer and fiber optic gyro respectively responsive starlight information, sunshine information, Geomagnetism Information and inertia information, carry out pretreatment through A/D conversion and fpga chip, pretreated data are input to the comprehensive treatment subsystem.Pretreated content comprises sunshine information, level and smooth, the star chart denoising of Geomagnetism Information and inertia information, distortion correction and barycenter extraction etc.; The comprehensive treatment subsystem, by the Flash memory device that performance-oriented DSP or ARM chip are aided with the SRAM that extends out or SDRAM memory device and extend out, importance in star map recognition, the starlight information of carrying out star sensor is resolved and is decided appearance based on sunshine information, Geomagnetism Information and the inertia information fusion of ant group particle filter algorithm.
The present invention's advantage compared with prior art is:
(1) introduces sunshine information and Geomagnetism Information, overcome the star sensor problem that information dropout causes accuracy of attitude determination to reduce when large attitude maneuver, be applicable to the integrated attitude determination of fine resolution earth observation maneuvering satellite of new generation;
(2) based on the disposal system of DSP or ARM chip+FPGA, introduced ant group particle filter algorithm, inertia information, starlight information, sunshine information and Geomagnetism Information are carried out information fusion, be applicable to the situation of non-Gaussian noise, improved accuracy of attitude determination;
(3) the processing unit height of star sensor, sun sensor, fiber optic gyro and microsensor is integrated, significantly improved the integrated level of system, reduced volume and the power consumption of system.
The specific embodiment
As shown in Figure 1, the present invention is comprised of responsive subsystem 1, acquisition of signal and preprocessing subsystem 2, comprehensive treatment subsystem 3.Responsive subsystem 1 mainly comprises CMOS star sensing probe 11, sun sensing probe 12, fiber optic gyro 13 and three-axle magnetic field probe 14, wherein CMOS star sensing probe 11 and 12 realizations of sun sensing probe are to the sensitivity of starlight information and sunshine information, the processing that converts thereof into corresponding electric signal and follow and amplify.For fear of sunshine to the interference of star sensor with make things convenient for the calculating of orbital coordinate system, the responsive optical axis stagger angle of CMOS star sensing probe 11 and sun sensing probe 12 is set to 90 degree, suppose that initial body coordinate system overlaps with orbital coordinate system, the quick optical axis direction of clock star is installed is overlapped with the Z axis reversing sense, the responsive optical axis direction of the sun overlaps and points to solar direction with Y-axis; Fiber optic gyro 13 is finished the sensitivity to inertia information on three mutually perpendicular directions, and converts thereof into corresponding electric signal, three-axle magnetic field probe 14 sensitivities of finishing Geomagnetism Information on three mutually perpendicular directions, and convert thereof into corresponding electric signal.
As shown in Figure 2, be acquisition of signal of the present invention and preprocessing subsystem 2 structural representations, this subsystem comprises A/D modular converter 21, fpga chip 22, configuring chip 23, SRAM or SDRAM memory device 24, clock circuit 25 and power module 26, wherein 21 receptions of A/D modular converter are from the starlight information of responsive subsystem 1, it is carried out being passed in the fpga chip 22 after the A/D conversion, wherein fpga chip 22 and supporting application configuration chip 23 thereof adopt respectively Spartan 3XC3S400 and the XCF02SV020C of Cypress company, belong to the series matching product, avoided the appearance of compatibling problem.Extended out SRAM memory device 24 in the periphery of fpga chip 22, in order to the sunshine information from responsive subsystem 1, inertia information, Geomagnetism Information and carry out buffer memory through the starlight information of A/D conversion.25 pairs of these subsystems of clock circuit provide independently clock signal, and power module 26 provides required 1.2V, 2.5V and 3.3V voltage for fpga chip 22, and provide 3.3V voltage for configuring chip 23.In the present embodiment, the starlight information that is received by 21 pairs of A/D converters is first carried out analogue to digital conversion, the starlight information after then will changing, and inertia information, and Geomagnetism Information and sunshine communication are in fpga chip 22.Around fpga chip 22, be provided with the SRAM memory device 24 that capacity is 2MByte, can store processing forward and backward data temporarily, play good buffer action; In configuring chip 23, packed in advance and realized comprising that star chart denoising, distortion correction, barycenter extract, and Geomagnetism Information, the functions such as inertia information smoothing, when fpga chip 22 received the data that responsive subsystem 1 transmits, program was just started working.After treated, can be by starlight information and sunshine information, Geomagnetism Information and inertia information through ant group particle filter, obtain the attitude output of integrated attitude determination system.
Owing to be subject to the impact of parasitic light and star sensor chip thermal noise and fixed pattern noise, cause the star map image of star sensor to be subject to noise emission.Therefore, carry out the accurate extraction of celestial body barycenter, must carry out image denoising to star chart and process.The design adopts the many small wave converting methods that obtain widespread use in the image denoising field, star chart is carried out the many wavelet transformations of CL, most energy centralizations of star chart in the subimage of lowest resolution, are carried out the many inverse wavelet transforms of CL to the image after the conversion, obtain the star chart after the denoising.
Because the installation error of len distortion and star sensor, and the characteristics of the large visual field of star sensor, large relative aperture, all can cause the distortion of star map image, the displacement that shows as the image slices vegetarian refreshments causes the object imaging to deform.Distortion correction is divided into following steps: at first the spatial coordinates at ideal image place is carried out conversion, make the ideal image pixel corresponding with the locus of actual fault image pixel, obtain corresponding distortion parameter, then according to the image slices vegetarian refreshments of reality, carry out interpolation, obtain the gray value of ideal image pixel.
In the design of star sensor, in order to obtain high-precision barycenter, generally camera lens to be carried out out of focus and process, a star imaging has several continuous points and forms, the star chart barycenter extracts and exactly these some continuous points is merged into same celestial body, and obtain the center of this celestial body.The method of relatively commonly using on the engineering at present is based on the star chart barycenter extraction algorithm of first moment, and as weights, the two-dimensional coordinate of pixel is coefficient with gray value, obtains the centroid position of each celestial body.
The sampling frequency of inertia information and Geomagnetism Information is higher, should not directly send into filter and directly carry out attitude algorithm, so first inertia information and Geomagnetism Information are carried out smothing filtering, to reach the purpose of frequency reducing, the information behind the smothing filtering are sent into filter finish attitude algorithm.
As shown in Figure 3, be comprehensive treatment subsystem 3 structural representations of the present invention, this subsystem comprises level shifter interface circuit 31, DSP or ARM chip 32, extend out Flash memory device 33, SRAM or SDRAM memory device 34, power module 35, clock circuit 36 and serial ports expansion module 37, wherein level shifter interface circuit 31 is with the asterism of acquisition of signal and preprocessing subsystem 2 outputs, centroid position information and level and smooth after inertia information, sunshine information, Geomagnetism Information carry out sending into dsp chip (TMS320C6711) or ARM chip (AT91RM9200) 32 after the level conversion.Required software program is solidificated in the Flash memory device 33 that extends out in advance in DSP or ARM chip 32 treating processs, has also extended out in addition SDRAM memory device 34 in order to the data before and after the stores processor.36 pairs of these subsystems of clock circuit provide independently clock signal, and power module 35 provides required 1.8V core voltage and the required 3.3V voltage of peripheral circuit for DSP or ARM chip 32.Utilize fast, the operational precision advantages of higher of DSP or ARM chip 32 processing speeds, finish the function of importance in star map recognition, and then in conjunction with sunshine information, Geomagnetism Information and inertia information realization integrated attitude determination.In the peripheral expansion of DSP or ARM chip 32 Flash memory device 33 and the equipment such as SDRAM memory device 34 and serial ports expansion module 37, wherein DSP or ARM chip 32 can directly be realized transceiving data by serial ports expansion module 37, Flash memory device 33 is used for loading the algorithm routine of realizing various functions, and SDRAM memory device 34 is used for the data before and after the stores processor.
As shown in Figure 4, be overall signal diagram of circuit of the present invention, the starlight information exchange is crossed CMOS star sensing probe 11, through behind the analogue to digital conversion, send into fpga chip 22 and carry out pretreatment, sunshine information, inertia information and Geomagnetism Information are passed through respectively sun sensing probe 12, fiber optic gyro 13, pop one's head in three-axle magnetic field, enter fpga chip 22 and carry out pretreatment, fpga chip 22 also can feed back simultaneously, and CMOS star sensing probe 11 is sent control signal, its exposure time of origin and concluding time are controlled, the control sun sensor, magnetometer, fiber optic gyro sends the frequency of data etc.Information after fpga chip 22 pretreatments just enters DSP or ARM chip 32 after the voltage transitions buffering, finish last attitude algorithm, integrated attitude determination etc. here, thereby obtains the integrated attitude determination result etc. of integrated attitude determination system.
As shown in Figure 5, integrated attitude determination system integrated attitude determination diagram of circuit based on ant group particle filter algorithm of the present invention, after the initialization, the starlight information that star sensing probe 11 sensitivities are arrived, the pop one's head in Geomagnetism Information of 14 sensitivities of the sunshine information of sun sensing probe 12 observation, three-axle magnetic field, and the inertia information that provides of the fiber optic gyro after error compensation 13, adopt optimum REQUEST algorithm, resolve and obtain quaternion q battle array as the observation information of ant group particle filter; This observation information is further combined with the inertia information through error compensation, by ant group particle filter, obtain on the one hand the attitude quaternion of integrated attitude determination system, obtaining on the other hand gyro wander estimates, output with the compensation gyro, resolved at last the attitude parameter of integrated attitude determination system by attitude quaternion, end of program.Wherein, ant group particle filter algorithm key step is:
(1) with the input as ant group particle filter of the quaternion q battle array that calculates and the inertia information after error compensation; On the basis of standard particle filtering algorithm, with the center particle of quaternion q battle array as standard particle filtering, and take it as with reference to produce N-1 particle according to standard normal distribution; Introduce ant group algorithm, carry out initialization: ant group algorithm maximum cycle Cmax, the heuristic factor-alpha of information, expected heuristic value β, pheromones intensity Q, pheromones volatility coefficient ρ, ant number m and number of particles N (q, q
1, q
2..., q
N-1);
(2) m ant placed on N the particle, make the weights θ of i particle
iInitialization information amount τ
i(0) be constant, and initial time Δ τ
i(0)=0; τ
i(t) expression t moment weights θ
iQuantity of information, Δ τ
i(t) represent that all ants stay weights θ constantly at t
iOn quantity of information and, t=1,2
(3) cycle number Count=Count+1, (the Count initial value is made as 0), the taboo list tabu of ant
kCall number k=1, wherein tabu
kThe current particle of passing by of expression ant k;
(4) the probability selection particle i that ant number k=k+1, ant individuality calculate according to following state transition probability formula also advances;
Wherein, p
i k(t) be state transition probability, η
i(t) be heuristic function, the expression ant is selected the expected degree of particle i, η
i(t)=1/ θ
i, θ
iThe weights of expression particle i;
(5) ant is moved on the new particle after choosing, and this particle is recorded in the taboo list of this ant individuality; If k<m then jumped to for (4) step, otherwise upgrades quantity of information on each particle according to following formula:
τ
i(t+N)=(1-ρ) τ
i(t)+Δ τ
i(t), cross weights θ when k ant
iThe time,
Wherein, L
kRepresent that k ant is in total number of this circulation particle of passing by;
(6) if Count<Cmax namely less than the ant group algorithm maximum cycle, empties taboo list and forwarded for (3) step to; Otherwise circulation finishes, and at this moment current particle is optimized and screens, and copies excellent particle, and keeping weights and be more greatly the many particles of quantity of information and eliminating weights little is the little particle of quantity of information; The less particle of weights is exchanged and makes a variation, avoid the particle tcam-exhaustion; Then utilize the particle that copies, exchanges and make a variation, and carry out particle filter in conjunction with inertia information and finish attitude and gyro wander estimation, and gyro wander is fed back to inertia information, error compensation.
The content that is not described in detail in the specification sheets of the present invention belongs to the known prior art of this area professional and technical personnel.