阅读说明：本技术 一种空间指向测量敏感器动态精度提升方法 (Method for improving dynamic precision of space directional measurement sensor ) 是由 王龙 武延鹏 袁利 王立 王晓燕 郑然� 于 2020-11-11 设计创作，主要内容包括：本发明涉及一种空间指向测量敏感器动态精度提升方法,属于空间飞行器用指向测量敏感器领域。采用压电微位移台支撑敏感器光电探测器,构成稳像系统；当敏感器转动时,在图像曝光时微动台驱动探测器进行补偿运动,减小星点成像拖尾；图像曝光完成后,结合微动台精密位移反馈,给出星点准确坐标,基于星点准确坐标进行测量结果解算并输出。本发明通过稳像提高动态下指向测量敏感器星点定位精度,从而提升敏感器动态精度。(The invention relates to a dynamic precision improving method of a space directional measurement sensor, and belongs to the field of directional measurement sensors for space aircrafts. A piezoelectric micro-displacement table is adopted to support a sensor photoelectric detector to form an image stabilizing system; when the sensor rotates, the micro-motion platform drives the detector to perform compensation motion during image exposure, so that star point imaging trailing is reduced; and after the image exposure is finished, combining with the precision displacement feedback of the micropositioner, giving out accurate coordinates of the star points, and resolving and outputting a measurement result based on the accurate coordinates of the star points. The invention improves the star point positioning precision of the dynamic downward pointing measurement sensor by image stabilization, thereby improving the dynamic precision of the sensor.)

1. A method for improving the dynamic precision of a space-pointing measurement sensor is characterized by comprising the following steps:

s1, constructing an image stabilization system: the method comprises the following steps that a piezoelectric micro-displacement table is adopted to support a photoelectric detector of a sensor, a supporting structure of the piezoelectric micro-displacement table is fixedly installed on a base of a space-oriented measuring sensor, the photoelectric detector is fixedly installed on a displacement surface of the piezoelectric micro-displacement table, an optical lens is fixedly installed on the base of the space-oriented measuring sensor through a holder, and a focal plane of the optical lens is enabled to be coincident with a photosensitive surface of the photoelectric detector to form an image stabilizing system;

s2, dynamic compensation of speed tracking: when the sensor rotates, the micro-displacement platform bears the detector to perform compensation motion along the row and column directions of the detector pixels within the time of generating a star image by image exposure, the compensation displacement is s, and when s is f multiplied by tan (w multiplied by t), the imaging tail of the star point is reduced to be 0; wherein f is the focal length of the sensor, t is the exposure time, and w is the rotation angular speed of the sensor;

s3, speed tracking dynamic compensation control: in the dynamic compensation of S2, the feedback of the sensor rotation angular speed given by the gyroscope is taken as the speed reference input wr; performing rotation transformation on displacement feedback d given by the piezoelectric ceramic to obtain real-time feedback wf of the speed of the micro-displacement platform, wherein wf is delta d/delta t/f, and delta represents differential quantity; obtaining micro-motion compensation quantity based on wr and wf, determining a corresponding driving electric signal by the piezoelectric ceramic control module according to the micro-motion compensation quantity, and driving the piezoelectric ceramic bearing photoelectric detector to complete speed tracking dynamic compensation control;

s4, centroid calculation: in S3, speed tracking dynamic compensation is triggered to start synchronously with image exposure, and the dynamic compensation is stopped simultaneously when the image exposure is finished; after the image exposure is finished, carrying out image processing according to a fixed star image generated by a photoelectric detector to finish star point imaging initial centroid extraction and obtain an initial centroid extraction result cp; after the speed tracking dynamic compensation is completed, obtaining the displacement feedback output by the piezoelectric ceramics, and completing the image surface position measurement to obtain an image surface position measurement result dp; combining the initial centroid extraction result cp and the image surface position measurement result dp to give accurate coordinates fp of the star point imaging centroid position, wherein fp is cp + dp, and centroid calculation is completed;

s5, under the dynamic condition, space pointing is resolved and output based on the accurate coordinates of the star point imaging mass center position, and the dynamic measurement precision of the space pointing measurement sensor is improved.

2. The method as claimed in claim 1, wherein the sensor comprises an optical lens, a holder, a base, a photodetector, a processing unit, a piezoelectric micro-displacement stage, a MEMS gyroscope, and a piezoelectric ceramic control module,

the piezoelectric micro-displacement platform comprises a displacement surface, a supporting structure and piezoelectric ceramics, wherein the displacement surface is arranged in the supporting structure, the displacement surface is connected with the supporting structure through the piezoelectric ceramics, a driving electric signal is applied to the piezoelectric ceramics through a piezoelectric ceramic control module, the driving piezoelectric ceramics bear the displacement surface to generate micro-displacement relative to the supporting structure, and meanwhile, the piezoelectric ceramics output a displacement measurement value.

3. The method as claimed in claim 2, wherein when no driving electrical signal is applied to the piezoelectric ceramic, the displacement surface is located at a stroke center position, referred to as a zero position, and the piezoelectric ceramic outputs a displacement measurement value of 0.

4. The method as claimed in claim 2, wherein the optical lens images a spatial star on a photosensitive surface of the photodetector, the star image is generated by photoelectric conversion of the photodetector, the star image is processed by the processing unit to obtain a spatial orientation measurement result, and the MEMS gyroscope is fixedly mounted on the base to measure the angular velocity of the spatial orientation measurement sensor in real time.

5. The method as claimed in claim 2, wherein when the sensor is in a static state, the angular velocity feedback of the MEMS gyroscope is 0, the driving electrical signal of the piezo-ceramic control module is 0, the piezo-electric micro-displacement surface is located at a zero position, the displacement feedback output by the piezo-electric ceramic is 0, and at this time, the optical axis of the optical lens passes through the center of the photosensitive surface of the photo detector, and the photo detector generates a star image, which is processed by the processing unit to complete the spatial orientation measurement.

6. The method as claimed in claim 2, wherein when the sensor rotates, the MEMS gyroscope provides a real-time rotational angular velocity feedback, the processing unit performs control calculation according to the angular velocity feedback and the current displacement feedback of the piezoelectric ceramic to obtain a micro-motion compensation amount, the piezoelectric ceramic control module provides a corresponding driving electrical signal according to the micro-motion compensation amount to drive the piezoelectric ceramic to bear a displacement surface to generate a compensation micro-motion relative to the supporting structure, and the photodetector generates a star image, which is processed by the processing unit to complete the spatial orientation measurement.

Technical Field

The invention belongs to the field of directional measurement sensors for space aircrafts, and relates to a dynamic precision improving method for a space directional measurement sensor.

Background

The space directional measurement sensor is based on imaging detection of a space point light source, measures target directional measurement information and self three-axis attitude information, and is widely applied to various spacecrafts such as satellites and spacecrafts due to the characteristics of high precision, high reliability and the like. The space direction measurement sensor extracts and matches image spot points of a shot image, and then calculates direction and attitude information. The coordinate information obtained by extracting the image spots is the basis for calculating pointing and attitude information, and in the actual use process, under the influence of the angular velocity of the spacecraft, the imaging position of the point light source on the image surface of the sensor changes within the integration time of the photoelectric detector, the image spots trailing, the signal-to-noise ratio of imaging detection is reduced, and the dynamic accuracy of pointing and attitude measurement is directly influenced.

The existing space direction measuring sensor realizes the dynamic precision index of the sensor by methods of reducing the integral time, increasing the caliber of an optical system, improving the performance of a detector, processing complex images and the like, and has poor effect.

Disclosure of Invention

The technical problem solved by the invention is as follows: the method overcomes the defects of the prior art, and provides the implementation method of the space-pointing measurement sensor based on image surface image stabilization, thereby reducing the star image point trailing, improving the signal-to-noise ratio of point light source dynamic imaging detection, and further improving the dynamic precision of the space-pointing measurement sensor.

The technical scheme of the invention is as follows:

a method for improving the dynamic precision of a space-pointing measurement sensor comprises the following steps:

s1, constructing an image stabilization system: the method comprises the following steps that a piezoelectric micro-displacement table is adopted to support a photoelectric detector of a sensor, a supporting structure of the piezoelectric micro-displacement table is fixedly installed on a base of a space-oriented measuring sensor, the photoelectric detector is fixedly installed on a displacement surface of the piezoelectric micro-displacement table, an optical lens is fixedly installed on the base of the space-oriented measuring sensor through a holder, and a focal plane of the optical lens is enabled to be coincident with a photosensitive surface of the photoelectric detector to form an image stabilizing system;

s2, dynamic compensation of speed tracking: when the sensor rotates, the micro-displacement platform bears the detector to perform compensation motion along the row and column directions of the detector pixels within the time of generating a star image by image exposure, the compensation displacement is s, and when s is f multiplied by tan (w multiplied by t), the imaging tail of the star point is reduced to be 0; wherein f is the focal length of the sensor, t is the exposure time, and w is the rotation angular speed of the sensor;

s3, speed tracking dynamic compensation control: in the dynamic compensation of S2, the feedback of the sensor rotation angular speed given by the gyroscope is taken as the speed reference input wr; performing rotation transformation on displacement feedback d given by the piezoelectric ceramic to obtain real-time feedback wf of the speed of the micro-displacement platform, wherein wf is delta d/delta t/f, and delta represents differential quantity; obtaining micro-motion compensation quantity based on wr and wf, determining a corresponding driving electric signal by the piezoelectric ceramic control module according to the micro-motion compensation quantity, and driving the piezoelectric ceramic bearing photoelectric detector to complete speed tracking dynamic compensation control;

s4, centroid calculation: in S3, speed tracking dynamic compensation is triggered to start synchronously with image exposure, and the dynamic compensation is stopped simultaneously when the image exposure is finished; after the image exposure is finished, carrying out image processing according to a fixed star image generated by a photoelectric detector to finish star point imaging initial centroid extraction and obtain an initial centroid extraction result cp; after the speed tracking dynamic compensation is completed, obtaining the displacement feedback output by the piezoelectric ceramics, and completing the image surface position measurement to obtain an image surface position measurement result dp; combining the initial centroid extraction result cp and the image surface position measurement result dp to give accurate coordinates fp of the star point imaging centroid position, wherein fp is cp + dp, and centroid calculation is completed;

s5, under the dynamic condition, space pointing is resolved and output based on the accurate coordinates of the star point imaging mass center position, and the dynamic measurement precision of the space pointing measurement sensor is improved.

Furthermore, the space direction measuring sensor comprises an optical lens, a holder, a base, a photoelectric detector, a processing unit, a piezoelectric micro-displacement platform, an MEMS gyroscope and a piezoelectric ceramic control module,

the piezoelectric micro-displacement platform comprises a displacement surface, a supporting structure and piezoelectric ceramics, wherein the displacement surface is arranged in the supporting structure, the displacement surface is connected with the supporting structure through the piezoelectric ceramics, a driving electric signal is applied to the piezoelectric ceramics through a piezoelectric ceramic control module, the driving piezoelectric ceramics bear the displacement surface to generate micro-displacement relative to the supporting structure, and meanwhile, the piezoelectric ceramics output a displacement measurement value.

Further, when the driving electric signal is not applied to the piezoelectric ceramic, the displacement surface is located at the stroke center position, which is called a zero position, and the piezoelectric ceramic outputs a displacement measurement value of 0.

Furthermore, the optical lens images the space fixed star on a photosensitive surface of the photoelectric detector, the fixed star image is generated through photoelectric conversion of the photoelectric detector, the fixed star image is processed by the processing unit to obtain a space direction measuring result, and the MEMS gyroscope is fixedly arranged on the base and is used for measuring the angular speed of the space direction measuring sensor in real time.

Further, when the spatial orientation measuring sensor is in a static state, the angular velocity feedback of the MEMS gyroscope is 0, the driving electric signal of the piezoelectric ceramic control module is 0, the piezoelectric micro-displacement surface is located at a zero position, the displacement feedback output by the piezoelectric ceramic is 0, the optical axis of the optical lens penetrates through the center of the photosensitive surface of the photoelectric detector at the moment, the photoelectric detector generates a star image, and the star image is processed by the processing unit to finish the spatial orientation measurement.

Furthermore, when the spatial orientation measuring sensor rotates, the MEMS gyroscope gives real-time rotation angular velocity feedback, the processing unit performs control calculation according to the angular velocity feedback and the current displacement feedback of the piezoelectric ceramics to obtain micro-motion compensation quantity, the piezoelectric ceramic control module gives corresponding driving electric signals according to the micro-motion compensation quantity to drive the piezoelectric ceramics to bear a displacement surface to generate compensation micro-displacement relative to the supporting structure, the photoelectric detector generates a star image, and the star image is processed by the processing unit to complete spatial orientation measurement.

Compared with the prior art, the invention has the beneficial effects that:

(1) the photoelectric detector is driven by the piezoelectric ceramics to perform compensation motion under a dynamic working condition, so that the star point imaging position change in the integration time is reduced, the dynamic star point imaging trailing length is reduced, and the dynamic measurement precision of the pointing measurement sensor is improved; compared with the prior art, the invention does not need to reduce the integration time of the detector, does not need to improve the caliber of an optical system and the photoelectric performance of the detector to ensure the signal-to-noise ratio, and the improvement of the dynamic precision of the pointing measurement sensor is not limited by the technology of optics and the detector;

(2) the invention adopts a speed tracking dynamic compensation mode to carry out displacement control on the piezoelectric micro-displacement platform, compensates the star point imaging position within the exposure time and realizes the real-time tracking of the detector on the star point imaging position; compared with the prior art, the method can keep the imaging position of the star point on the detector unchanged in the integration time under the dynamic condition, and effectively reduce the influence of pixel nonuniformity on dynamic star point positioning;

(3) according to the invention, after the integration of the detector is finished, the initial centroid of the star point is extracted, and the accurate coordinates of the imaging position of the star point are obtained by combining the precise displacement feedback output by the piezoelectric ceramics; compared with the prior art, the method converts the offset of the star point coordinate which cannot be accurately determined originally by the imaging trailing interference into the linear displacement of the micropositioner which can be accurately determined, introduces the precise linear displacement feedback to determine the star point coordinate, and improves the dynamic precision.

Drawings

FIG. 1 is a constitutional view of the present invention;

FIG. 2 is a control strategy diagram of the present invention;

fig. 3 illustrates the working steps of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

The invention is applied to a space extremely high precision pointing measurement project, as shown in fig. 1, 2 and 3, the specific implementation steps are as follows:

s1, constructing an image stabilization system: the sensor photoelectric detector is supported by a piezoelectric micro-displacement platform, a supporting structure of the piezoelectric micro-displacement platform is fixedly arranged on a base of a space directional measurement sensor, the photoelectric detector is fixedly arranged on a displacement surface of the piezoelectric micro-displacement platform, and an optical lens is fixedly arranged on the base through a holder, so that a focal plane of the optical lens is enabled to be coincident with a photosensitive surface of the photoelectric detector, and an image stabilization system is formed. Aiming at the requirement of the spatial orientation ultrahigh dynamic measurement precision of the project, a piezoelectric micro-displacement platform with the displacement feedback precision of 1 nanometer is selected, and a photoelectric detector with the pixel size of 4.5 micrometers is carried to form an image stabilizing system.

S2, dynamic compensation of speed tracking: when the sensor rotates, the micro-displacement platform bears the detector to perform compensation motion along the row and column directions of the detector pixels within the exposure time, the focal length of the sensor is set to be f, the rotation angular speed of the sensor within the exposure time t is set to be w, the compensation micro-displacement of the micro-displacement platform is set to be s, and when s is f × tan (w × t), the star point imaging tailing can be reduced to be 0. The focal length of the sensor is 1 meter, the rotation angular speed of the sensor is 0.06 degree/second within 10 milliseconds of exposure time, when the compensation micro-displacement of the micro-displacement platform reaches 10.5 microns within the exposure time, the star point imaging tailing is 0, and if the speed tracking dynamic compensation is not carried out, the star point imaging tailing is larger than 2 pixels.

S3, speed tracking dynamic compensation control: in the dynamic compensation, the processing unit takes sensor rotation angular speed feedback given by a gyroscope as speed reference input wr; the processing unit performs rotation transformation on the displacement feedback d given by the piezoelectric ceramic to obtain the real-time feedback wf of the speed of the micro-displacement platform, wherein wf is delta d/delta t/f, and delta represents differential quantity; and substituting wr and wf into control and resolving to obtain micro-motion compensation quantity, and driving the piezoelectric ceramic bearing photoelectric detector to complete micro-motion adjustment by the piezoelectric ceramic control module according to the corresponding driving electric signal given by the micro-motion compensation quantity.

S4, centroid calculation: the speed tracking dynamic compensation is triggered to start synchronously by the same trigger source as the image exposure, and the dynamic compensation is stopped simultaneously when the image exposure is finished; after the image exposure is finished, the processing unit carries out image processing according to the star image generated by the photoelectric detector to finish the star point imaging initial centroid extraction; after the speed tracking dynamic compensation is completed, obtaining the displacement feedback output by the piezoelectric ceramics to complete the image surface position measurement; and combining the initial centroid extraction result cp and the image surface position measurement result dp to give accurate coordinates fp of the star point imaging position, wherein the fp is cp + dp, and the centroid calculation is completed.

The space direction measuring sensor comprises an optical lens, a holder, a base, a photoelectric detector, a processing unit, a piezoelectric micro-displacement table, an MEMS gyroscope and a piezoelectric ceramic control module,

the piezoelectric micro-displacement platform comprises a displacement surface, a supporting structure and piezoelectric ceramics, wherein the displacement surface is arranged in the supporting structure, the displacement surface is connected with the supporting structure through the piezoelectric ceramics, a driving electric signal is applied to the piezoelectric ceramics through a piezoelectric ceramic control module, the driving piezoelectric ceramics bear the displacement surface to generate micro-displacement relative to the supporting structure, and meanwhile, the piezoelectric ceramics output a displacement measurement value.

When the driving electric signal is not applied to the piezoelectric ceramic, the displacement surface is located at the stroke center position, which is called zero position, and the piezoelectric ceramic outputs a displacement measurement value of 0.

The optical lens images the space fixed star on a photosensitive surface of the photoelectric detector, the space fixed star image is generated through photoelectric conversion of the photoelectric detector, the fixed star image is processed by the processing unit to obtain a space direction measuring result, and the MEMS gyroscope is fixedly arranged on the base and is used for measuring the angular speed of the space direction measuring sensor in real time.

When the spatial orientation measuring sensor is in a static state, the angular velocity feedback of the MEMS gyroscope is 0, the piezoelectric ceramic control module drives an electric signal to be 0, the piezoelectric micro-displacement surface is located at a zero position, the displacement feedback output by the piezoelectric ceramic is 0, the optical axis of the optical lens penetrates through the center of the photosensitive surface of the photoelectric detector at the moment, the photoelectric detector generates a star image, and the star image is processed by the processing unit to finish the spatial orientation measurement.

When the space direction measuring sensor rotates, the MEMS gyroscope gives real-time rotation angular velocity feedback, the processing unit performs control calculation according to the angular velocity feedback and the current displacement feedback of the piezoelectric ceramics to obtain micro-motion compensation quantity, the piezoelectric ceramics control module gives corresponding driving electric signals according to the micro-motion compensation quantity to drive the piezoelectric ceramics to bear a displacement surface to generate compensation micro-displacement relative to the supporting structure, the photoelectric detector generates a star image, and the star image is processed by the processing unit to complete space direction measurement.

In the project implementation, the displacement feedback precision reaches 1 nanometer, the precision of the image surface position measurement result dp reaches 1 nanometer, and the influence of the dynamic state on the measurement precision can be ignored under the condition that the focal length of the sensor is 1 meter. Under the dynamic condition, the accurate coordinates of the star point imaging position acquired by the invention are used for carrying out space pointing calculation and output, the dynamic measurement precision can be basically consistent with the static state, the influence of star point imaging trailing is avoided, and the dynamic measurement precision of the space pointing measurement sensor is improved.

The photoelectric detector is driven by the piezoelectric ceramics to perform compensation motion under a dynamic working condition, so that the star point imaging position change in the integration time is reduced, the dynamic star point imaging trailing length is reduced, and the dynamic measurement precision of the pointing measurement sensor is improved; compared with the prior art, the invention does not need to reduce the integration time of the detector, does not need to improve the caliber of an optical system and the photoelectric performance of the detector to ensure the signal-to-noise ratio, and the improvement of the dynamic precision of the pointing measurement sensor is not limited by the technology of optics and the detector;

the invention adopts a speed tracking dynamic compensation mode to carry out displacement control on the piezoelectric micro-displacement platform, compensates the star point imaging position within the exposure time and realizes the real-time tracking of the detector on the star point imaging position; compared with the prior art, the method can keep the imaging position of the star point on the detector unchanged in the integration time under the dynamic condition, and effectively reduce the influence of pixel nonuniformity on dynamic star point positioning;

according to the invention, after the integration of the detector is finished, the initial centroid of the star point is extracted, and the accurate coordinates of the imaging position of the star point are obtained by combining the precise displacement feedback output by the piezoelectric ceramics; compared with the prior art, the method converts the offset of the star point coordinate which cannot be accurately determined originally by the imaging trailing interference into the linear displacement of the micropositioner which can be accurately determined, introduces the precise linear displacement feedback to determine the star point coordinate, and improves the dynamic precision.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.