Automatic astronomical observation system and observation method

Abstract

An automatic astronomical observation system includes an astronomical telescope (1), a star finding servo motor (2) for driving the astronomical telescope (1), and a control system (4). A focusing servo motor (3) is connected to a lens regulation mechanism of the astronomical telescope (1); a CMOS sensor (5) used for obtaining a starry sky image is disposed on the astronomical telescope (1); the control system (4) includes a control chip, a gyroscope, a memory, and a WIFI communication interface; the control chip is electrically connected to the CMOS sensor (5), the gyroscope, the memory, and the WIFI communication interface; a handheld device provided with a WIFI communication interface is disposed by being fitted to the control system (4); and a GPS module is disposed in the control system (4) or the handheld device. Also provided is an automatic astronomical observation method.

Claims

1. An automatic astronomical observation method comprising providing an automatic astronomical observation system and the steps of automatic star finding, automatic focusing and image storing, wherein, said automatic astronomical observation system comprises: an astronomical telescope, a star finding servo motor for driving the astronomical telescope, and a control system, wherein a focusing servo motor is connected to a lens regulation mechanism of the astronomical telescope; a CMOS sensor used for obtaining a starry sky image is disposed on the astronomical telescope; said control system comprises a control chip, a gyroscope, a memory, and a WIFI communication interface; said control chip is electrically connected to the CMOS sensor, the gyroscope, the memory, and the WIFI communication interface; a handheld device provided with a WIFI communication interface is disposed by being fitted to the control system; and a GPS module is disposed in the control system or the handheld device; said automatic star finding step comprises: getting geographic coordinates and a time information of a current position by the GPS module, checking and obtaining a current sky map using the handheld device; sending a sky map of a celestial body to be observed to the control system from the handheld device; the control system obtains information from the gyroscope for determining an inclination of a tube; according to a deviation between the current position of the tube and a direction pointing to the celestial body to be observed, the control system controls a move of the star finding servo motor, to adjust a horizontal position and an angle of elevation of the tube, to find the star automatically; and said automatic focusing step comprises: the control system controls the CMOS image sensor to obtain an image signal; the image signal is transmitted to the handheld device via the WIFI communication interface; the handheld device processes the image signal, for planets in a solar system, using a maximum value of a high-frequency component of the image signal as a focus aim, for extrasolar stars, using a maximum contrast as the focus aim, the handheld device sends focus information to the control system via the WIFI communication interface for controlling the movement of the focusing servo motor, to focus automatically.

2. The automatic astronomical observation method according to claim 1, wherein for the planets in the solar system, the automatic focus step comprises: (1) getting the image signal, in which P (i,j) represents a gray scale value of a point (i, j) in the image signal, where i is an integer of 1˜m, j is an integer of 1˜n, m and n are numbers of horizontal and vertical pixels in the image signal; (2) using an adaptive low-pass filter based on a least mean square algorithm (LMS), to filter out high frequency components, to obtain the image signal P.sub.r(i,j); (3) calculating an energy of the image signal before filtering $E_P=\underset{i=1}{\overset{m}{.Math.}}\underset{j=1}{\overset{n}{.Math.}}{P}^2\left(i,j\right),$ and an energy of the image signal after filtering $E_{P_r}=\underset{i=1}{\overset{m}{.Math.}}\underset{j=1}{\overset{n}{.Math.}}{P}_r^2\left(i,j\right)$ respectively; (4) calculating the energy lost after filtering, which is E.sub.i=E.sub.P−E.sub.P.sub.r, the automatic focus step is completed when E.sub.i gets to a maximum.

3. The automatic astronomical observation method according to claim 2, wherein, the automatic focus step comprises: {circle around (1)} setting a focal length to change in a step value F.sub.c; a maximum step value is F.sub.max, a minimum step value is F.sub.min, that is, if F.sub.c>F.sub.max after a change of the step value of the focal length then let F.sub.c=F.sub.max; if F.sub.c<F.sub.max after the change of the step value of the focal length then let F.sub.c=F.sub.min; the step value of the focal length changes in ΔF in each adjustment; {circle around (2)} setting the step value of the focal length to F.sub.c=F.sub.max; {circle around (3)} rotating a focus servo motor counterclockwise to a limit position, getting an image of a current location, calculating the energy lost after filtering, which is E.sub.i1; {circle around (4)} rotating the focus servo motor clockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the energy lost after filtering, which is E.sub.i2; {circle around (5)} rotating the focus servo motor clockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the energy lost after filtering, which is E.sub.i3; {circle around (6)} if E.sub.i1<E.sub.i2<E.sub.i3, indicating that a direction of an adjustment makes an image clearer, then, if E.sub.i2−E.sub.i1<E.sub.i3−E.sub.i2, then let F.sub.c=F.sub.c+ΔF, namely to increase the step value; if E.sub.i2−E.sub.i1>E.sub.i3−E.sub.i2, then let F.sub.c=F.sub.c−ΔF, namely to reduce the step value; let E.sub.i1=E.sub.i2, and repeat step {circle around (5)}; if E.sub.i3<E.sub.i2<E.sub.i1, indicate the direction of the adjustment makes the image fuzzier, an initial step value of the focal length is too large, let F.sub.c=E.sub.c−ΔF, and repeat steps {circle around (3)}˜{circle around (5)}, if F.sub.c=F.sub.min, rotates the focus servo motor counterclockwise to the limit position, this position is a best focus position; if, E.sub.i3<E.sub.i2<E.sub.i1 indicating a position of a focus is near a position corresponding to E.sub.i2, then set F.sub.c=F.sub.min; {circle around (7)} rotating the focus servo motor counterclockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the energy lost after filtering, which is E.sub.im, {circle around (8)} if E.sub.im>E.sub.i3 then let repeat step {circle around (7)}; if E.sub.im<E.sub.i3 then rotating the focus servo motor clockwise so that the focal length changes F.sub.c, the position is the best focus position.

4. The automatic astronomical observation method according to claim 1, wherein, for extrasolar stars, the automatic focus step comprises: (1) getting image signal P (i,j), where i is an integer of 1˜m, j is an integer of 1˜n, m and n are numbers of horizontal and vertical pixels in the image signal, P represents a gray scale value of a point (i, j) in the image signal; (2) calculating an image grey scale probability density function G(r), that is, a ratio of the number of pixels with gray scale r and a total number of pixels of the image signal; (3) calculating a contrast $C=\underset{i=1}{\overset{m}{.Math.}}\underset{j=1}{\overset{n}{.Math.}}\left({.Math.P\left(i+1,j\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i+1,j\right)-P\left(i,j\right).Math.\right)+{.Math.P\left(i-1,j\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i-1,j\right)-P\left(i,j\right).Math.\right)+{.Math.P\left(i,j+1\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i,j+1\right)-P\left(i,j\right).Math.\right)+{.Math.P\left(i,j-1\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i,j-1\right)-P\left(i,j\right).Math.\right)\right);$ (4) adjusting a focus servo motor based on a value of C, when C takes a maximum value, a focus is achieved.

5. The automatic astronomical observation method according to claim 4, wherein, the automatic focus step comprises: {circle around (1)} setting a focal length to change in a step value F.sub.c; a maximum step value is F.sub.max, a minimum step value is F.sub.min, that is, if F.sub.c>F.sub.max after a change of a step value of the focal length then let F.sub.c=F.sub.max; if F.sub.c<F.sub.min after the change of the step value of the focal length then let F.sub.c=F.sub.min; the step value of the focal length changes in ΔF in each adjustment; {circle around (2)} setting the step value of the focal length to F.sub.c=F.sub.max; {circle around (3)} rotating the focus servo motor counterclockwise to the limit position, getting the image of the current location, calculating the contrast, which is C.sub.1; {circle around (4)} rotating the focus servo motor clockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the contrast, which is C.sub.2; {circle around (5)} rotating the focus servo motor clockwise again so that the focal length changes F.sub.c; getting the image of the current location, calculating the contrast, which is C.sub.3; {circle around (6)} if C.sub.1<C.sub.2<C.sub.3, indicating that a direction of an adjustment makes an image clearer, then, if C.sub.2−C.sub.1<C.sub.3−C.sub.2, then let F.sub.c=F.sub.c+ΔF, namely to increase the step value; if C.sub.2−C.sub.1>C.sub.3−C.sub.2 then let F.sub.c=F.sub.c−ΔF, let and C.sub.1=C.sub.2 and C.sub.2=C.sub.3, repeat step {circle around (5)}; if C.sub.3<C.sub.2<C.sub.1, indicate the direction of the adjustment makes the image fuzzier, an initial step value of the focal length is too large, let F.sub.c=F.sub.c−ΔF, and repeat steps {circle around (3)}˜{circle around (5)}, if F.sub.c=F.sub.min, rotates the focus servo motor counterclockwise to the limit position, this position is a best focus position; if C.sub.1<C.sub.2>C.sub.3, indicating the position of the focus is near the position corresponding to C.sub.2, then set F.sub.c=F.sub.min; {circle around (7)} rotating the focus servo motor counterclockwise so that the focal length changes getting the image of the current location, calculating the contrast, which is; {circle around (8)} if C.sub.m>C.sub.3, then let C.sub.3=C.sub.m, repeat step {circle around (7)}; if C.sub.m<C.sub.3, then rotating the focus servo motor clockwise so that the focal length changes F.sub.c, the position is the best focus position.

6. The automatic astronomical observation method according to claim 1, wherein, when performing auto-focus, a process to transmit images via the WIFI communication interface comprises, compressing the image signal, P(i,j) represents a gray scale value of a point (i, j) in the image signal, where i is an integer of 1˜m, j is an integer of 1˜n, m and n are numbers of horizontal and vertical pixels in the image signal, when i, j are both odd, let P (i, j)=[P (i, j)+P (i+1, j)+P (i, j+1)+P (i+1, j+1)]/4, use a mean value of the grey value of four adjacent pixels to represent the gray value, and transmit the compressed the image signal; when dealing with image storage after focus, transfer the uncompressed image signal through the WIFI communication interface.

7. The automatic astronomical observation method according to claim 1, wherein said control chip is a field programmable gate array.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of the hardware of the system in embodiment 1;

(2) FIG. 2 is a schematic diagram of the telescope system in the embodiment.

(3) Wherein: 1, astronomical telescopes; 2, star finding servo motor; 3, focusing servo motor; 4, the control system; 5, CMOS sensor.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) The present invention will be further described below with reference to drawings and examples.

Embodiment

(5) Refer to FIG. 1 and FIG. 2, an automatic astronomical observation system constituted with a telescope system and a handheld device. The telescope system comprises an astronomical telescope 1, a star finding servo motor 2 for driving the astronomical telescope, a focusing servo motor 3 connected to a lens regulation mechanism of the astronomical telescope, and a control system 4; a CMOS sensor 5 used for obtaining a starry sky image is disposed on the astronomical telescope 1; the control system comprises a field programmable gate array (FPGA), a gyroscope, a memory, a WIFI communication interface, and a GPS module; the control chip is electrically connected to the CMOS sensor, the gyroscope, the memory, the WIFI communication interface and the GPS module; said handheld device has a WIFI communication interface, the handheld device communicate with the control system through the WIFI communication interface.

(6) In this embodiment, the handheld device may be a tablet or smartphone supporting Android/IOS system with a WIFI communication interface. A software will be run on the device to display the current sky map, choose the stars to be observed, show to pictures of the celestial bodies, share the pictures online, introduce astronomical knowledge, transmit data with the telescope in both way, etc. The astronomical telescope can be a Schmidt-Cassegrain telescope; the star finder of the astronomical telescope may be consisted by a biaxially DC servo motor with an encoder and an electric equatorial.

(7) Setting by a software, the system can achieve the following functions: Opening a software on a handheld device, showing the current observable sky map based on the current position and time information obtained through GPS, by clicking or searching mode to specify the celestial body wishing to observe and transmit the information to the telescope control system via WIFI, the control system adjusts a DC servo motor based on the information obtained from the GPS module and a gyroscope module, so that the telescope automatically track the selected target, while according to the set observation mode, focus using the autofocus method based on image processing to get a clear view of the stars. During this process, the CMOS sensor continuously collect star images and transferred to smart handheld devices via WIFI module for display, after performing the focus process, the functions of image storing, post-processing, network sharing and so on can be selected.

(8) To achieve these functions, the following techniques are used:

(9) 1, Autofocus technology based on image processing

(10) Using different algorithms depending on the celestial bodies chosen for observation:

(11) (1) For the observation of the planets in the solar system

(12) In the solar system, the planets can be seen in the telescope with much larger size, so the target is to see the clear details of the planet.

(13) According to the knowledge of image processing, the captured image will be clearer with more high frequency component information. So the focus servo motor can be rotated correspondingly, to let the clarity reaches the maximum value. The detail steps are described as following:

(14) a) Getting the image P (i,j), in which i:1˜m, j:1˜n, P represents the gray level of a point in the image;

(15) b) Using adaptive low-pass filter based on the least mean square algorithm (LMS), to filter out the high frequency components, to obtain the image P.sub.r(i, j);

(16) c) Calculating the energy of the image before filtering

(17) $E_P=\underset{i=1}{\overset{m}{.Math.}}\underset{j=1}{\overset{n}{.Math.}}{P}^2\left(i,j\right),$
and the energy of the image after filtering

(18) $E_{P_r}=\underset{i=1}{\overset{m}{.Math.}}\underset{j=1}{\overset{n}{.Math.}}{P}_r^2\left(i,j\right)$
respectively;

(19) d) Calculating the energy lost after filtering, which is E.sub.i=E.sub.P−E.sub.P.sub.r, the focus processing is completed when E.sub.i get to the maximum.

(20) As in the process of adjusting the focal length, the curve of the value of E.sub.i is unimodal, in order to search the optimum focal length quickly, the focusing method is:

(21) a) setting the focal length to change in the step value F.sub.c; the maximum step value is F.sub.max, the minimum step value is F.sub.min, that is, if F.sub.c>F.sub.max after the change of the step value of the focal length then let F.sub.c=F.sub.max; if F.sub.c<F.sub.min after the change of the step value of the focal length then let F.sub.c=F.sub.min; the step value of the focal length changes in ΔF in each adjustment (whose minimum value is determined by the mechanical properties, this value can be set by software);

(22) b) Setting the step value of the focal length to F.sub.c=F.sub.max;

(23) c) Rotating the focus servo motor counterclockwise to the limit position, getting the image of the current location, calculating the energy lost after filtering, which is E.sub.i1;

(24) d) Rotating the focus servo motor clockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the energy lost after filtering, which is E.sub.i2;

(25) e) Rotating the focus servo motor clockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the energy lost after filtering, which is E.sub.i3;

(26) f) If E.sub.i1<E.sub.i2<E.sub.i3, indicating that the direction of the adjustment makes the image clearer, then, if E.sub.i2−E.sub.i1<E.sub.i3−E.sub.i2, then let F.sub.c=F.sub.c+ΔF, namely to increase the step value; if E.sub.i2−E.sub.i1>E.sub.i3−E.sub.i2, then let F.sub.c=F.sub.c−ΔF, namely to reduce the step value; let E.sub.i1=E.sub.i2, and repeat step {circle around (5)};

(27) if E.sub.i3<E.sub.i2<E.sub.i1, indicate the direction of the adjustment makes the image fuzzier, the initial step value of the focal length is too large, let F.sub.c=F.sub.c−ΔF, and repeat steps {circle around (3)}˜{circle around (5)}, if F.sub.c=F.sub.min, rotates the focus servo motor counterclockwise to the limit position, this position is the best focus position;

(28) if E.sub.i3<E.sub.i2>E.sub.i1, indicating the position of the focus is near the position corresponding to E.sub.i2, then set F.sub.c=F.sub.min;

(29) g) Rotating the focus servo motor counterclockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the energy lost after filtering, which is E.sub.im;

(30) h) If E.sub.im>E.sub.i3, then let E.sub.i3=E.sub.im, repeat step {circle around (7)}; if E.sub.im<E.sub.i3, then rotating the focus servo motor clockwise so that the focal length changes F.sub.c, the position is the best focus position.

(31) After performing the focus process, photographing the celestial bodies and transmitting to the handheld device for storage.

(32) (2) Extrasolar Stars

(33) For the observation of the overview of the nebula, take the maximum contrast as the focus target. The detail steps are described as following:

(34) a) Getting the image P (i,j), in which i:1˜m, j:1˜n, P represents the gray level of a point in the image;

(35) b) Calculating the contrast

(36) $C=\underset{i=1}{\overset{m}{.Math.}}\underset{j=1}{\overset{n}{.Math.}}\left({.Math.P\left(i+1,j\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i+1,j\right)-P\left(i,j\right).Math.\right)+{.Math.P\left(i-1,j\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i-1,j\right)-P\left(i,j\right).Math.\right)+{.Math.P\left(i,j+1\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i,j+1\right)-P\left(i,j\right).Math.\right)+{.Math.P\left(i,j-1\right)-P\left(i,j\right).Math.}^{2}G\left(.Math.P\left(i,j-1\right)-P\left(i,j\right).Math.\right)\right);$

(37) c) The image will be clearer with larger C. When C takes the maximum value, the focus is achieved.

(38) As in the process of adjusting the focal length, the curve of the value of C is unimodal, in order to search the optimum focal length quickly, the focusing method is:

(39) a) setting the focal length to change in the step value F.sub.c; the maximum step value is F.sub.max, the minimum step value is F.sub.min, that is, if F.sub.c>F.sub.max after the change of the step value of the focal length then let F.sub.c=F.sub.min; if F.sub.c<F.sub.min after the change of the step value of the focal length then let F.sub.c=F.sub.min; the step value of the focal length changes in ΔF in each adjustment (whose minimum value is determined by the mechanical properties, this value can be set by software);

(40) b) Setting the step value of the focal length to F.sub.c=F.sub.max;

(41) c) Rotating the focus servo motor counterclockwise to the limit position, getting the image of the current location, calculating the contrast, which is C.sub.1;

(42) d) Rotating the focus servo motor clockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the contrast, which is C.sub.2;

(43) e) Rotating the focus servo motor clockwise again so that the focal length changes F.sub.c; getting the image of the current location, calculating the contrast, which is C.sub.3;

(44) f) If C.sub.1<C.sub.2<C.sub.3, indicating that the direction of the adjustment makes the image clearer, then, if C.sub.2−C.sub.1<C.sub.3−C.sub.2, then let F.sub.c=F.sub.c+ΔF, namely to increase the step value; if C.sub.2−C.sub.1>C.sub.3−C.sub.2, then let F.sub.c=F.sub.c−ΔF, let C.sub.1=C.sub.2 and C.sub.2=C.sub.3, and repeat step {circle around (5)};

(45) if C.sub.3<C.sub.2<C.sub.1, indicate the direction of the adjustment makes the image fuzzier, the initial step value of the focal length is too large, let F.sub.c=F.sub.c−ΔF, and repeat steps {circle around (3)}˜{circle around (5)}, if F.sub.c=F.sub.min, rotates the focus servo motor counterclockwise to the limit position, this position is the best focus position;

(46) if C.sub.1<C.sub.2>C.sub.3, indicating the position of the focus is near the position corresponding to C.sub.2, then set F.sub.c=F.sub.min;

(47) g) Rotating the focus servo motor counterclockwise so that the focal length changes F.sub.c; getting the image of the current location, calculating the contrast, which is C.sub.m;

(48) h) If C.sub.m>C.sub.3, then let C.sub.3=C.sub.m, repeat step {circle around (7)}; if C.sub.m<C.sub.3, then rotating the focus servo motor clockwise so that the focal length changes F.sub.c, the position is the best focus position.

(49) After performing the focus process, photographing the celestial bodies and transmitting to the handheld device for storage.

(50) 2. The image transmission technology between the handheld device and the telescope.

(51) The images transmit between the handheld device and the telescope by WIFI. In the process of focusing, in order to increase the speed of interaction, the images are not needed to transmit in full, so a pixel binding technology is adopted to decrease the size of the image transmitted, so as to complete the focusing process quickly; after focusing, obtain and transmit images with more pixels according to the needs, to meet the demand for observation, storage and sharing of the celestial images.

(52) With the choice of the different data size in different situation corresponding to the focus process, it can meet the demands of the fast focus, and it also can transmit high quality images for the users to save after focusing. The basic process is as follows: Let CMOS/CCD have the pixel of X of the full size, when focusing is not completed, the gray scale values of the four adjacent pixels is averaged at that point for transmission, as follows:

(53) TABLE-US-00001 P(i, j) P(i, j + 1) P(i + 1, j) P(i + 1, j + 1)

(54) Calculating as P (i, j)=[P (i, j)+P (i+1, j)+P (i, j+1)+P (i+1, j+1)]/4, so the total number of pixels transmitted will be X/4, which greatly reduces the amount of data transmitted during focusing. The technology has not been described in the prior literatures or patents in the field of telescope image transmission.

(55) 3. An automatic star finding technology without calibration.

(56) Based on the information like current position, time and tube angles obtained from the gyroscope and GPS, the system can complete the automatic star finding process without calibration, so it can automatically point to the celestial body predetermined to observe.

(57) The technique relies on access to current geographical coordinates and time information through GPS module, so that you can query the current sky map drawn under the observation points, so as to determine the stars can be observed by the user. The handheld device can show the corresponding map of the sky on the screen after obtaining these information. These information will be transmitted to the control system of the telescope via WIFI when the user selects the stars to be observed. The telescope tube's inclination data can be obtained through the gyroscope module, that shows the direction of the telescope to the star map, adjusting the tube of the telescope through calculating the deviation between the position of the star and the tube, which including the angle in horizon plate and the inclination, when the deviation is less than the set threshold, the automatic star finding is completed.

(58) By using the techniques described above, the present embodiment achieves automatic star finding, automatic focusing and wireless operation of astronomical telescope.