An Automatic High-Precision Focusing Method and System for the Main Optical Path of a Telescope

Abstract

The present invention relates to the field of telescope focusing, and specifically relates to an automatic high-precision focusing method and system for the main optical path of a telescope. The method and system first collect data values of several factors that affect the focal length of the telescope multiple times, and then use statistical analysis methods and the multiple non-linear regression method to obtain the relationship between the focusing amount and different factors, and pre-calculate the focusing amount to achieve the function of automatic focusing. Through the present invention, the focusing position can be determined by different influencing factors, and then the focal length of the main optical path can be automatically adjusted to achieve the purpose of automatic focusing when external factors change.

Description

Technical Field

[0001] The present invention relates to the field of telescope focusing, and in particular, to an automatic high-precision focusing method and system for the main optical path of a telescope. Background Art

[0002] The focusing system of the main optical path of a telescope generally adjusts the lens group or the camera. The accuracy of the focusing system plays a crucial role in the alignment of the rear optical path and the imaging of the camera. If accurate focusing cannot be achieved, defocusing will occur, resulting in unclear imaging and seriously affecting the imaging quality. The focusing amount that the focusing system needs to adjust is affected by factors such as the working temperature, the object distance of the observation target, and the position of the pitch axis of the telescope under different working conditions.

[0003] Currently, when generally focusing on the main optical path of a telescope, the defocus state of the image is observed or recorded, the focusing amount that needs to be adjusted is calculated based on the defocus state, and then a focusing instruction is sent to the focusing mechanism manually or directly to drive the focusing mechanism to focus, so as to achieve the purpose of focusing. However, using this method is prone to the phenomenon of focusing lag. Especially when tracking high-speed dynamic targets, the object distance changes greatly and the change speed is also fast. Therefore, the amount of focal length that needs to be adjusted is large and the speed is fast. Calculating the focusing amount by collecting the defocus of the image will inevitably cause focusing lag and result in incorrect focusing. In addition, focusing is affected by many factors. When the distance of the observation target changes, focusing is required. When the pitch axis of the telescope changes, it will cause a change in the focal length of the main optical path and focusing is required. When the temperature changes, it will also cause a change in the focal length of the main optical path and focusing is required. Therefore, it is very difficult to determine the reason for the change in the focal length and the amount of focusing required only through images. Summary of the Invention

[0004] The embodiments of the present invention provide an automatic high-precision focusing method and system for the main optical path of a telescope, so as to at least solve the technical problem in the prior art that the factors causing the change in the focal length and the corresponding focusing amount cannot be determined.

[0005] According to an embodiment of the present invention, an automatic high-precision focusing method for the main optical path of a telescope is provided, including the following steps:

[0006] Collect data values of several factors affecting the focal length of the telescope multiple times;

[0007] Adopt a statistical analysis method and use a multiple non-linear regression method to obtain the relationship between the focusing amount and different factors, and pre-calculate the focusing amount.

[0008] Further, the several factors affecting the focal length of the telescope include: the object distance of the target position, the temperature value, and the position value of the pitch axis of the telescope.

[0009] Further, the change in the target position includes observing a target whose moving position changes, or when the telescope changes the observed target, the positions of different targets are different.

[0010] Further, a statistical analysis method and a multiple non-linear regression method are used to obtain the relationship between the focusing amount and different factors. The pre-calculated focusing amount includes:

[0011] Measure the influence of the change in one factor data on the focusing amount multiple times. Obtain the optimal focusing position by observing the image, and at the same time record the absolute focusing position amount obtained by feedback. Then change the other two influencing factors in turn to obtain the influence of the two factors on the focusing amount. Then, use the multiple non-linear regression least squares fitting method to fit and obtain the multiple non-linear regression equation.

[0012] Further, a statistical analysis method and a multiple non-linear regression method are used to obtain the relationship between the focusing amount and different factors. The pre-calculated focusing amount includes:

[0013] Compare the in-focus image with the current image to determine whether the current image is in focus. When the image is in focus, record the focusing position feedback value. Then, use the multiple non-linear least squares fitting method based on the focusing position feedback value to obtain the preliminary focusing control amount;

[0014] Compare the preliminary focusing control amount with the focusing position feedback value, and use the focusing closed-loop control amount to obtain the position deviation.

[0015] According to another embodiment of the present invention, there is provided an automatic high-precision focusing system for the main optical path of a telescope, including:

[0016] A sensor unit for collecting data values of several factors affecting the focal length of the telescope multiple times;

[0017] A controller for using a statistical analysis method and a multiple non-linear regression method to obtain the relationship between the focusing amount and different factors, and pre-calculating the focusing amount.

[0018] Further, the controller controls the focusing mechanism to operate the focusing according to the required focusing amount through a control instruction.

[0019] Further, the focusing system is located at the main focus position of the telescope, and drives the focusing camera or lens group through the focusing mechanism of the main optical path of the telescope to change its position to achieve the focusing of the main optical path.

[0020] Further, after calculating the focusing amounts required by different factors, then send a focusing instruction to the controller of the automatic focusing position to drive the main optical path focusing mechanism to drive the focusing camera or lens group to move.

[0021] Further, a high-precision position sensor and a temperature sensor are installed in the focusing system. Meanwhile, the angle information of the elevation axis of the telescope is transmitted to the controller of the focusing mechanism for statistical focusing calculation;

[0022] Among them, the position sensor installed in the focusing system accurately measures the real-time position of the focusing mechanism. The position value of the elevation axis of the telescope is accurately measured by an encoder and transmitted to the focusing system. The temperature sensor installed in the focusing system measures the external working temperature. The object distance of the target position is calculated through the target orbit information and the telescope installation position information.

[0023] A processor is used to run a program. When the program runs, it executes the automatic high-precision focusing method for the main optical path of the telescope in any one of the above.

[0024] A processor is used to run a program. When the program runs, it executes the automatic high-precision focusing method for the main optical path of the telescope in any one of the above.

[0025] In the automatic high-precision focusing method and system for the main optical path of the telescope in the embodiments of the present invention, first, data values of several factors affecting the telescope focal length are collected multiple times. Then, a statistical analysis method and a multiple nonlinear regression method are used to obtain the relationship between the focusing amount and different factors, and the focusing amount is calculated in advance to achieve the function of automatic focusing. Through the present invention, the focusing position can be determined by different influencing factors, and then the focal length of the main optical path can be automatically adjusted to achieve the purpose of automatic focusing when external factors change. Description of the Drawings

[0026] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1 is the flowchart of the automatic high-precision focusing method for the main optical path of the telescope of the present invention;

[0028] Figure 2 is the distribution and composition diagram of the automatic high-precision focusing system for the main optical path of the telescope of the present invention;

[0029] Figure 3 is the focusing position curve diagram when the elevation axis changes in the automatic high-precision focusing method for the main optical path of the telescope of the present invention;

[0030] Figure 4 is the dimming and focusing control architecture diagram in the automatic high-precision focusing method for the main optical path of the telescope of the present invention. Detailed Embodiments

[0031] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data used in appropriate cases can be interchanged so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] Embodiment 1

[0034] According to an embodiment of the present invention, an automatic high-precision focusing method for the main optical path of a telescope is provided. Refer to Figure 1 , including the following steps:

[0035] S100: Collect data values of several factors affecting the focal length of the telescope multiple times;

[0036] S200: Use the method of statistical analysis and the multiple nonlinear regression method to obtain the relationship between the focusing amount and different factors, and pre-calculate the focusing amount.

[0037] In the automatic high-precision focusing method for the main optical path of the telescope in the embodiment of the present invention, first, data values of several factors affecting the focal length of the telescope are collected multiple times, and then the method of statistical analysis and the multiple nonlinear regression method are used to obtain the relationship between the focusing amount and different factors, and the focusing amount is pre-calculated to achieve the function of automatic focusing. Through the present invention, the focusing position can be determined by different influencing factors, and then the focal length of the main optical path can be automatically adjusted to achieve the purpose of automatic focusing when external factors change.

[0038] Among them, several factors affecting the focal length of the telescope include: the object distance at the target position, the temperature value, and the position value of the telescope's pitch axis.

[0039] Among them, the change in the target position includes observing a target whose moving position changes, or when the telescope changes the observed target, the positions of different targets are different.

[0040] Among them, the relationship between the focusing amount and different factors is obtained by using the method of statistical analysis and the multivariate non-linear regression method. The pre-calculated focusing amount includes:

[0041] Measure the influence of the change of a factor data on the focusing amount multiple times, obtain the optimal focusing position by observing the image, record the absolute focusing position amount obtained by feedback at the same time, and then change the other two influencing factors in turn to obtain the influence of the two factors on the focusing amount, and then obtain the multivariate non-linear regression equation by fitting with the multivariate non-linear regression least squares fitting method.

[0042] Among them, the relationship between the focusing amount and different factors is obtained by using the method of statistical analysis and the multivariate non-linear regression method. The pre-calculated focusing amount includes:

[0043] By comparing the in-focus image and the current image, determine whether the current image is in focus. When the image is in focus, record the focusing position feedback value, and then obtain the preliminary focusing control amount by using the multivariate non-linear least squares fitting method according to the focusing position feedback value;

[0044] Compare the preliminary focusing control amount with the focusing position feedback value, and obtain the position deviation by using the focusing closed-loop control amount.

[0045] The following takes a specific embodiment to illustrate in detail the automatic high-precision focusing method for the main optical path of the telescope of the present invention:

[0046] The present invention analyzes the reasons for the change of the focal length of the main optical path of the telescope, uses multiple measurement tests to test the influence of different reasons on the imaging focal length of the main optical path, and then uses the method of statistical analysis and the multivariate non-linear regression method to obtain the relationship between the focusing amount and different factors, pre-calculate the focusing amount, and directly control the focusing mechanism to operate according to the required focusing amount by the controller through control instructions, so as to realize the function of automatic focusing. In order to achieve high-precision and accurate focusing, a high-precision position feedback component (position sensor) and a temperature sensor are installed in the focusing system, and at the same time, the angle information of the elevation axis of the telescope is transmitted to the controller of the focusing mechanism for statistical focusing calculation.

[0047] The distribution and composition of the focusing system in the present invention are as Figure 2 shown, where the telescope includes an azimuth axis and an elevation axis. The azimuth axis rotates parallel to the ground plane, and the elevation axis rotates perpendicular to the ground plane. The specific movement directions are as Figure 2As shown in the figure. The focusing system of the main optical path of the telescope is located at the prime focus position of the telescope. The focusing mechanism of the main optical path drives the focusing camera or lens group to change its position to achieve the focusing of the main optical path. It can be found from the figure that when the position of the observation target changes, in order to obtain a clear image, the focal length will change and focusing is required. The change in the target position includes observing a target, and the moving position of the target changes. Or when the telescope changes the observation target, the positions of different targets are different. When observing a target, the azimuth axis and elevation axis of the telescope will change. At this time, due to the action of gravity, the focal length of the focusing system will change and focusing is required. In different seasons, the working temperature will change greatly, and focusing is also required at this time.

[0048] When the telescope is working, under different working conditions, data on various factors affecting the focal length of the telescope are collected multiple times, including the object distance, temperature value, and elevation axis position value of the target position. Using the method of data statistics and the method of multivariate non-linear regression analysis to fit and calculate the focusing control amount required by different factors, and then send a focusing instruction to the controller at the automatic focusing position to drive the main optical path focusing mechanism to drive the focusing camera or lens group to move. Among them, the position sensor installed in the focusing mechanism of the focusing system accurately measures the real-time position of the focusing mechanism. The position value of the elevation axis of the telescope is accurately measured by the encoder and transmitted to the focusing system. The temperature sensor installed in the focusing system measures the external working temperature. The object distance of the target position is calculated through the target orbit information and the telescope installation position information.

[0049] In the present invention, the focusing amount is obtained through the method of multivariate non-linear regression fitting calculation by data statistics. The influencing factors of the focusing amount are specifically the object distance of the target position, the working environment temperature, and the elevation axis position of the telescope. Measure the influence on the focusing amount when these data factors change multiple times, obtain the optimal focusing position through observing the image, and at the same time record the absolute focusing position amount obtained by the feedback of the focusing mechanism. Then, change the other two influencing factors in turn to obtain the influence of the two factors on the focusing amount, and then obtain the multivariate non-linear regression equation through the method of least squares fitting of multivariate non-linear regression. The recorded focusing adjustment amount is P c , the recorded object distance of the target position is D, the position of the elevation axis of the telescope is recorded as EL, the working temperature T is recorded, and the focusing position feedback is recorded as P f , the multivariate variable X = (D, T, EL), so it can be known that the multivariate function P c = f(D, T, EL).

[0050] Measure D by changing the object distance of the target position, and record the changed target positions multiple times as D1, D2....D N , change the temperature value T multiple times, and record the temperature values T1, T2...T N, change the elevation axis position EL multiple times, and record the elevation axis positions as EL1, EL2... EL N , when the object distance, temperature, and elevation axis change at each target position, drive the focusing camera or lens group by manual open-loop control of the focusing mechanism, and observe through the image at the same time. When the image is clear through focusing, record the displacement feedback value P of the focusing mechanism at this time f0 、P f1 ...P fN . Then it can be recorded that:

[0051] {P f0 、P f1 ...P fN} = f(X i ) = f(D i , T i , EL i )(i = 1, 2,... N)

[0052] where N is the actual number of sampling points.

[0053] A functional relationship of n variables can be established between multiple influencing factors and the focusing amount as follows, where n is the number of influencing elements:

[0054]

[0055] Therefore, a function can be solved

[0056] such that the function satisfies:

[0057]

[0058] where W i is the weight of the fitting function.

[0059] And can take the form of trigonometric functions or polynomial forms.

[0060] Through experimental tests, the focusing position feedback amount has a linear relationship with temperature, a linear relationship with the observed object distance, and a non-linear relationship with the elevation axis position value. From the test data, when the elevation axis runs from the horizontal to the zenith direction (0° to 85°), the main optical path focusing position and the elevation axis position show a non-linear relationship, but when the elevation axis runs from the zenith direction (85° to 0°), the main optical path focusing position and the elevation axis position show another non-linear relationship. Specifically as Figure 3 shown, so the present invention performs segmented processing on this.

[0061] Specifically, it is to determine the running speed of the telescope elevation axis, where the running speed of the elevation axis is calculated through the position transmitted back by the elevation axis, and the elevation axis controller has a certain frequency Tk Sent to the focusing controller at the current moment t k The position value of the pitch axis is θ k At the previous moment t k-1 The position value θ of the pitch axis k-1 At this time, the pitch axis speed is:

[0062]

[0063] 1. When v k > 0, that is, when the telescope moves from horizontal to zenith, the sine fitting method is adopted. As can be seen from the above, the function form is:

[0064]

[0065] Where α0, α1... α n Include weight coefficients and fitting coefficients.

[0066] After fitting, take

[0067] Record

[0068]

[0069] α3 = α3'b;

[0070] After obtaining b, the following can be obtained:

[0071]

[0072] Substitute a set of actual measurement data X0, EL0;

[0073] Then the following can be obtained

[0074] Then the non - linear parameters can be parameterized into linear parameters and calculated after refinement.

[0075] 2. When v k < 0, that is, when the telescope moves from zenith to horizontal, the polynomial fitting method is adopted.

[0076] After fitting, take

[0077] To obtain the fitting coefficients:

[0078] Define From the necessary conditions for taking extreme values, it is known that the solution

[0079] Satisfying the condition constitutes the fitting coefficients. Therefore, the normal equations can be obtained:

[0080] Among them:

[0081]

[0082]

[0083] After linearizing the fitting function from non - linear to linear, based on the measured data, a multiple linear function can be obtained:

[0084]

[0085] Making the function satisfy:

[0086]

[0087] The corresponding normal equations can be written as:

[0088]

[0089] Where (x 11 , x 12 .... x 1N ) = (D1, D2.... D N );

[0090] (x 21 , x 22 .... x 2N ) = (T1, T2.... T N );

[0091] (x 31 , x 32 .... x 3N ) = (EL1, EL2.... EL N );

[0092] (y1, y2.... y N ) = (P f0 , P f1 ... P fN );

[0093] Finally

[0094] Through this method, each fitting coefficient can be obtained, and finally, a fitting formula can be obtained through the fitting coefficients:

[0095]

[0096] From the fitted curve, the focusing command value at any different object distance, temperature, and telescope pitch axis condition within the controller sampling interval can be obtained, and then this command value is fed forward to the focusing controller for focusing control. The specific focusing control architecture is as shown in Figure 4 shown.

[0097] As Figure 4 known, through multiple experiments, under different temperatures, different object distances of the observation target, and different telescope pitch axis positions, by comparing the in-focus image and the current image, it is determined whether the current image is in focus. When the image is in focus, the focusing position feedback value is recorded, and then according to the measured values, the above-mentioned multivariate nonlinear least squares fitting method is used to obtain the focusing control amount. At the same time, it is compared with the focusing position feedback, and the position deviation P err = P c - P f is obtained, where the focusing feedback is filtered by a low-pass filter for noise filtering and then calculated. The filtering is calculated as follows:

[0098] P ff (n) = (1 - β)P ff (n - 1)+βP f (n)

[0099] where is the filtering coefficient, T s is the sampling time of the controller, generally the closed-loop calculation time interval, f c is the cut-off frequency of the low-pass filter, and the noise of the focusing feedback position higher than this cut-off frequency is filtered out.

[0100] The focusing control amount P cc calculated above realizes the purpose of focusing by controlling the movement of the focusing mechanism.

[0101] Among them, the focusing closed-loop controller can adopt an anti-integral saturation integral separation digital PID controller or other closed-loop controllers. If an anti-saturation digital incremental PID controller is adopted, the incremental algorithm can reduce the cumulative calculation amount of the position type. The control increment ΔP cc (k) and the control amount P cc (k) can be obtained:

[0102]

[0103] P cc (k) = P cc (k - 1)+ΔP cc (k);

[0104] where K p is the proportional coefficient of PID, T iis the integral coefficient, and T d is the differential coefficient. χ is the integral separation parameter.

[0105] Set an error threshold ε > 0. When the error P cc (k) > ε, cancel the integral term. When P cc (k) < ε, increase the integral term.

[0106]

[0107] The position output can be calculated therefrom to drive the focusing mechanism to move.

[0108] Through the present invention, it is possible to determine the focusing position by different influencing factors, and then automatically adjust the focal length of the main optical path, so as to achieve the purpose of automatic focusing when external factors change.

[0109] Embodiment 2

[0110] According to another embodiment of the present invention, there is provided an automatic high-precision focusing system for the main optical path of a telescope, including:

[0111] A sensor unit for collecting data values of several factors affecting the focal length of the telescope multiple times;

[0112] A controller for obtaining the relationship between the focusing amount and different factors by using statistical analysis methods and multivariate non-linear regression methods, and pre-calculating the focusing amount.

[0113] In the automatic high-precision focusing system for the main optical path of the telescope in the embodiment of the present invention, first, data values of several factors affecting the focal length of the telescope are collected multiple times, and then the relationship between the focusing amount and different factors is obtained by using statistical analysis methods and multivariate non-linear regression methods, and the focusing amount is pre-calculated to achieve the function of automatic focusing. Through the present invention, it is possible to determine the focusing position by different influencing factors, and then automatically adjust the focal length of the main optical path, so as to achieve the purpose of automatic focusing when external factors change.

[0114] Among them, the controller controls the focusing mechanism to operate according to the required focusing amount through control instructions.

[0115] Among them, the focusing system is located at the main focus position of the telescope, and the focusing camera or lens group is driven by the focusing mechanism of the main optical path of the telescope to change its position to achieve focusing of the main optical path.

[0116] Among them, after calculating the focusing amounts required by different factors, a focusing instruction is then sent to the controller at the automatic focusing position to drive the main optical path focusing mechanism to drive the focusing camera or lens group to move.

[0117] Among them, a high-precision position sensor and a temperature sensor are installed in the focusing system, and at the same time, the angle information of the elevation axis of the telescope is transmitted to the controller of the focusing mechanism for statistical focusing calculation;

[0118] The position sensor installed in the focusing system accurately measures the real-time position of the focusing mechanism. The position value of the elevation axis of the telescope is accurately measured by an encoder and transmitted to the focusing system. The temperature sensor installed in the focusing system measures the external working temperature. The object distance of the target position is calculated through the target orbit information and the telescope installation position information.

[0119] The following takes a specific embodiment to describe the telescope main optical path automatic high-precision focusing system of the present invention in detail:

[0120] The present invention analyzes the reasons for the change of the focal length of the telescope main optical path, uses multiple measurement tests to test the influence of different reasons on the imaging focal length of the main optical path, and then uses the statistical analysis method to obtain the relationship between the focusing amount and different factors by using the multiple nonlinear regression method, pre-calculates the focusing amount, and directly controls the focusing mechanism to operate according to the required focusing amount through a control instruction by the controller, thereby realizing the function of automatic focusing. To achieve high-precision and accurate focusing, a high-precision position feedback element (position sensor) and a temperature sensor are installed in the focusing system, and at the same time, the angle information of the elevation axis of the telescope is transmitted to the controller of the focusing mechanism for statistical focusing calculation.

[0121] The distribution and composition of the focusing system in the present invention are as Figure 2 shown. Among them, the telescope includes an azimuth axis and an elevation axis. The azimuth axis rotates parallel to the ground plane, and the elevation axis rotates perpendicular to the ground plane. The specific movement directions are as Figure 2 shown. The focusing system of the telescope main optical path is located at the main focus position of the telescope. The focusing mechanism of the main optical path drives the focusing camera or lens group to change its position to achieve the focusing of the main optical path. It can be found from the figure shown that when the observation target position changes, in order to obtain a clear image, the focal length will change and focusing is required. Among them, the change of the target position includes observing a target, and the movement position of this target changes. Or when the telescope changes the observation target, the positions of different targets are different. When observing a target, the azimuth axis and elevation axis of the telescope will change. At this time, due to the influence of gravity, the focal length of the focusing system will change and focusing is required. In different seasons, the working temperature will change greatly, and focusing is also required at this time.

[0122] When the telescope is working, data on various factors affecting the telescope's focal length are collected multiple times under different working conditions. The object distance, temperature value, and the position value of the telescope's pitch axis at the target position are collected. Using the method of data statistics and the multivariate non - linear regression analysis method, the focusing control amount required for different factors is fitted and calculated. Then, a focusing instruction is sent to the controller at the automatic focusing position to drive the focusing mechanism in the main optical path to drive the focusing camera or lens group to move. Among them, a position sensor installed in the focusing mechanism in the focusing system accurately measures the real - time position of the focusing mechanism. The position value of the telescope's pitch axis is accurately measured by an encoder and transmitted to the focusing system. A temperature sensor is installed in the focusing system to measure the external working temperature. The object distance at the target position is calculated through the target track information and the telescope installation position information.

[0123] In the present invention, the focusing amount is obtained through the data - statistical multivariate non - linear regression fitting calculation method. The influencing factors of the focusing amount are specifically the object distance at the target position, the working environment temperature, and the position of the telescope's pitch axis. The influence of changes in these data factors on the focusing amount is measured multiple times. The optimal focusing position is obtained by observing the image, and at the same time, the absolute focusing position amount obtained from the feedback of the focusing mechanism is recorded. At the same time, the other two influencing factors are changed in turn to obtain the influence of the two factors on the focusing amount. Then, the multivariate non - linear regression equation is obtained by fitting through the multivariate non - linear regression least - squares fitting method. Among them, the recorded focusing adjustment amount is P c , the recorded object distance at the target position is D, the position of the telescope's pitch axis is recorded as EL, the working temperature is recorded as T, and the focusing position feedback is recorded as P f , the multivariate variable X=(D, T, EL). Therefore, it can be known that the multivariate function P c =f(D, T, EL).

[0124] Measure D by changing the object distance at the target position. The target positions changed multiple times are recorded as D1, D2....D N , change the temperature value T multiple times, and record the temperature values T1, T2...T N , change the position of the pitch axis EL multiple times, and record the position of the pitch axis as EL1, EL2...EL N , when the object distance, temperature, and pitch axis at the target position change each time, the focusing mechanism is driven to drive the focusing camera or lens group through manual open - loop control, and at the same time, it is observed through the image. When the image is in focus, record the displacement feedback value P f0 、P f1 ...P fN . Then it can be recorded:

[0125] {P f0 、P f1 ...P fN}=f(X i )=f(D i,T i ,EL i (i = 1, 2,... N)

[0126] where N is the actual number of sampling points.

[0127] A multi - element function relationship can be established between multiple influencing factors and the focusing amount as follows, where n is the number of influencing elements:

[0128]

[0129] Therefore, a function can be solved

[0130] such that the function satisfies:

[0131]

[0132] where W i is the weight of the fitting function.

[0133] And it can take the form of trigonometric functions or polynomial forms.

[0134] Through experimental tests, the feedback amount of the focusing position has a linear relationship with temperature, a linear relationship with the distance of the observed target, and a non - linear relationship with the position value of the pitch axis. From the test data, when the pitch axis runs from the horizontal to the zenith direction (0° - 85°), the focusing position of the main optical path and the pitch axis position show a non - linear relationship. However, when the pitch axis runs from the zenith direction (85° - 0°), the focusing position of the main optical path and the pitch axis position show another non - linear relationship. Specifically, as Figure 3 shown, so the present invention performs segmented processing on this.

[0135] Specifically, it is to determine the running speed of the telescope pitch axis. The running speed of the pitch axis is calculated through the position transmitted back by the pitch axis. The pitch axis controller sends it to the focusing controller at a certain frequency T k at the current moment t k the position value of the pitch axis is θ k , and at the previous moment t k-1 the position value of the pitch axis θ k-1 , at this time the pitch axis speed:

[0136]

[0137] 1. When v k > 0, that is, when the telescope moves from the horizontal to the zenith, the sine fitting method is adopted. As mentioned above, the function form:

[0138]

[0139] Among them, α0, α1...α n include weight coefficients and fitting coefficients.

[0140] After fitting, take

[0141] Record

[0142]

[0143] α3 = α3'b;

[0144] After obtaining b, the following can be obtained:

[0145]

[0146] Substitute a set of actual measurement data X0, EL0;

[0147] Then the following can be obtained

[0148] Then, after parameterizing the non-linear parameters into linear parameters, it can be calculated.

[0149] 2. When v k < 0, that is, when the telescope moves from the zenith to the horizontal, the method of polynomial fitting is adopted.

[0150] After fitting, take

[0151] To obtain the fitting coefficient:

[0152] Define From the necessary condition for taking the extreme value, it is known that the solution that satisfies the condition

[0153] The solution of constitutes the fitting coefficient. Therefore, the normal equations can be obtained:

[0154] Among them:

[0155]

[0156]

[0157] After linearizing the fitting function from non-linear to linear, according to the measured data, a multiple linear function can be obtained:

[0158]

[0159] Make the function satisfy:

[0160]

[0161] The corresponding normal equations can be written as:

[0162]

[0163] where (x 11 , x 12 .... x 1N ) = (D1, D2.... D N );

[0164] (x 21 , x 22 .... x 2N ) = (T1, T2.... T N );

[0165] (x 31 , x 32 .... x 3N ) = (EL1, EL2.... EL N );

[0166] (y1, y2.... y N ) = (P f0 , P f1 ... P fN );

[0167] Finally

[0168] By this method, each fitting coefficient can be obtained, and finally the fitting formula can be obtained through the fitting coefficients:

[0169]

[0170] From the fitted curve, the focusing command value at any different object distance, temperature, and telescope pitch axis condition within the controller sampling interval can be obtained, and then the command value is fed forward to the focusing controller for focusing control. The specific focusing control architecture is as Figure 4 shown.

[0171] As Figure 4 can be seen, through multiple experiments under different temperatures, different object distances of the observed target, and different telescope pitch axis positions, by comparing the in-focus image and the current image, it is determined whether the current image is in focus. When the image is in focus, the focusing position feedback value is recorded, and then the focusing control quantity is obtained by using the above-mentioned multivariate nonlinear least squares fitting method according to the measured values. At the same time, it is compared with the focusing position feedback, and the position deviation P err = P c - P f, where the focus feedback is filtered for noise through a low-pass filter and then calculated, and the filtering is performed through the following calculation:

[0172] P ff (n) = (1 - β)P ff (n - 1) + βP f (n)

[0173] where is the filtering coefficient, T s is the sampling time of the controller, generally the closed-loop calculation time interval, f c is the cut-off frequency of the low-pass filter, and the noise of the focus feedback position higher than this cut-off frequency is filtered out.

[0174] The focus control amount P calculated from the above cc achieves the purpose of focusing by controlling the movement of the focusing mechanism.

[0175] Among them, the focus closed-loop controller can adopt an anti-integral saturation integral separation digital PID controller or other closed-loop controllers. If an anti-saturation digital incremental PID controller is adopted, the incremental algorithm can reduce the cumulative calculation amount of the position type. The control increment ΔP cc (k) and the control amount P cc (k):

[0176]

[0177] P cc (k) = P cc (k - 1) + ΔP cc (k);

[0178] where K p is the proportional coefficient of PID, T i is the integral coefficient, T d is the differential coefficient. χ is the integral separation parameter.

[0179] Set an error threshold ε > 0. When the error P cc (k) > ε, cancel the integral term. When P cc (k) < ε, add the integral term.

[0180]

[0181] From this, the position output can be calculated to drive the focusing mechanism to move.

[0182] Through the present invention, it is possible to determine the focusing position from different influencing factors and then automatically adjust the focal length of the main optical path to achieve the purpose of automatic focusing when external factors change.

[0183] Example 3

[0184] A storage medium stores a program file capable of implementing the automatic high-precision focusing method for the main optical path of the telescope described in any one of the above.

[0185] Embodiment 4

[0186] A processor is used to run a program. When the program runs, it executes the automatic high-precision focusing method for the main optical path of the telescope described in any one of the above.

[0187] The serial numbers of the embodiments of the present invention above are only for description and do not represent the advantages or disadvantages of the embodiments.

[0188] In the above embodiments of the present invention, the descriptions of the respective embodiments have their own emphases. For parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0189] In several embodiments provided by the present application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the system embodiments described above are only illustrative. For example, the division of units can be a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of units or modules can be in electrical or other forms.

[0190] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0191] In addition, the functional units in each embodiment of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0192] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present invention. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, read-only memories (ROMs), random access memories (RAMs), mobile hard disks, magnetic disks, or optical discs.

[0193] The foregoing are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An automatic high-precision focusing method for the main optical path of a telescope, characterized in that Including the following steps: Collecting data values of several factors affecting the telescope focal length multiple times; Adopting the method of statistical analysis and using the multiple nonlinear regression method to obtain the relationship between the focusing amount and different factors, and pre-calculating the focusing amount; The adopting the method of statistical analysis and using the multiple nonlinear regression method to obtain the relationship between the focusing amount and different factors, and pre-calculating the focusing amount includes: Measuring multiple times the influence of the change of a factor data on the focusing amount, obtaining the optimal focusing position through observing the image, simultaneously recording the absolute focusing position amount obtained by feedback, and then sequentially changing the other two influencing factors to obtain the influence of the two factors on the focusing amount, and then fitting through the multiple nonlinear regression least squares fitting method to obtain the multiple nonlinear regression equation; Alternatively, by comparing the in-focus image and the current image, determining whether the current image is in focus, when the image is in focus, recording the focusing position feedback value, and then obtaining the preliminary focusing control amount by using the multiple nonlinear least squares fitting method according to the focusing position feedback value; Comparing the preliminary focusing control amount with the focusing position feedback value, and obtaining the position deviation by using the focusing closed-loop control amount.

2. The automatic high-precision focusing method for the main optical path of the telescope according to claim 1, characterized in that Several factors affecting the telescope focal length include: the object distance of the target position, the temperature value, and the telescope pitch axis position value.

3. The automatic high-precision focusing method for the main optical path of the telescope according to claim 2, wherein The change of the target position includes observing a target, the moving position of the target changes, or when the telescope changes the observed target, the positions of different targets are different.

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