Horizontal measurement method for flexible aircraft with high aspect ratio

Abstract

The invention discloses a horizontal measurement method for a high-aspect-ratio flexible aircraft. The method comprises the following steps: sequentially measuring the positions of all point positions of a fuselage, wings and an empennage under a gravity coordinate system (OXYZ1); and then, based on a least square fitting method, isolating differences among a point 1L, a point 1R, a point A and a point B in the gravity direction caused by high aspect ratio flexible deformation, and fitting a scale parameter lambda, a rotation parameter matrix R and a translation parameter T obtained by calculation to construct an optimal fitting coordinate system (OXYZ2). All point position coordinates (X1, Y1 and Z1) of the airplane under the gravity coordinate system (OXYZ1) are sequentially converted to the fitting coordinate system (OXYZ2), point coordinates (X2, Y2 and Z2) after fitting are obtained, and the result after fitting is made to better conform to the actual situation so as to recognize global deformation. Starting from isolation of inherent deformation, a weight fitting method is provided in the aircraft horizontal measurement process, the overall fitting deviation is reduced, the fitted result better conforms to the actual situation, and horizontal measurement can be more accurately carried out.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft level measurement, and in particular relates to a method for level measurement of a flexible aircraft with a large aspect ratio. Background Art

[0002] Aircraft horizontal measurement is to check the relative position of each aircraft component, the quality of component installation and its deformation during use. With the rapid development of the country's advanced manufacturing industry, the size and shape measurement of large equipment faces problems such as large measurement space, high relative accuracy requirements, and complex measured features. Laser tracker is one of the most effective means of large-scale measurement. For large rigid equipment, multi-station measurement or a combination of multiple measurement systems is often used. Through the joint observation of common points by measuring instruments at different stations, the respective measurement data are converted to the same coordinate system, and then full-size fitting is performed according to the selection of key feature points, so as to achieve the purpose of effectively identifying global deformation.

[0003] However, for flexible aircraft with small wing loads such as solar and hydrogen energy, the relative deformation of the whole aircraft is large and the amount of change is unknown. There are local deformations near key feature points that have not been accurately identified in advance. When measuring and analyzing the entire aircraft, the traditional rigid body data processing method cannot achieve the purpose of effectively isolating inherent deviations in global analysis, and will pass the fitting error to the final analysis result, which is prone to erroneous analysis directions and conclusions that are obviously inconsistent with the actual situation. Summary of the invention

[0004] The purpose of the present invention is to provide a method for horizontal measurement of a flexible aircraft with a large aspect ratio, aiming to solve the above-mentioned problems, reduce the deviation of the flexible aircraft horizontal measurement data analysis, and lay the foundation for analyzing the conclusions that conform to the actual situation.

[0005] The present invention is mainly achieved through the following technical solutions:

[0006] A method for measuring the level of a flexible aircraft with a large aspect ratio, comprising the following steps:

[0007] Step S1: In the theoretical coordinate system (O XYZ0 ), symmetrical key fitting points are selected in the lateral and longitudinal directions of the aircraft respectively as the lateral reference leveling points and the longitudinal reference leveling points of the aircraft; the key fitting points are the rigid points of the connection area between the wing and the landing gear;

[0008] Step S2: Use the laser tracker to build the station and establish the original gravity coordinate system (O XYZ1 ), and its Z-axis direction coincides with the gravity direction; then, horizontal leveling and vertical leveling are performed based on the horizontal reference leveling point and the vertical reference leveling point respectively;

[0009] Step S3: measure the gravity coordinate system (OXYZ1 ) The positions of the fuselage, wing and tail points are calculated; then, based on the least squares fitting method, the differences in the gravity direction between point 1L, point 1R, point A and point B caused by the flexible deformation of the large aspect ratio are isolated, and the scale parameter λ, rotation parameter matrix R and translation parameter T calculated are fitted to construct the best fitting coordinate system (O XYZ2 ):

[0010]

[0011] Where: (X 1 , Y 1 , Z 1 ) is the gravity coordinate system (O XYZ1 ) below;

[0012] (X 2 , Y 2 , Z 2 ) is the best fitting coordinate system (O XYZ2 ) below;

[0013] Step S31: first solve the scale parameter λ;

[0014] According to the set weight (P X , P Y , P Z ), using formula (2) to calculate the theoretical coordinate system (O XYZ0 ) are processed by gravity centering. Similarly, the gravity coordinate system (O XYZ1 ) are subjected to barycentric processing and converted into barycentric coordinates with their respective barycenters as the origins. Then, the scale parameter λ is calculated according to formula (3):

[0015]

[0016] Where: (X 0 , Y 0 , Z 0 ) is the theoretical coordinate system (O XYZ0 ) below;

[0017] is the theoretical coordinate system (O XYZ0 ) is the average value of the coordinates of each key fitting point;

[0018] is the gravity coordinate system (O XYZ1 ) is the average value of the coordinates of each key fitting point;

[0019] Step S32: solving the rotation parameter matrix R;

[0020] The rotation parameter matrix R is a third-order orthogonal matrix, and |R| = 1, then R is expressed as formula (4) through parameters containing a, b, and c, and is respectively brought into the theoretical coordinate system (O XYZ0 ) and the gravity coordinate system (O XYZ1 ) to obtain the centroidal coordinates of the key fitting points, and then obtain the equations (5) and (6) after the centroidal coordinates of the key fitting points. According to the equation (7), a, b, and c can be calculated, and then R can be obtained from the equation (4):

[0021]

[0022] Step S33: solving the translation parameter T;

[0023]

[0024] Where: (X T , Y T , Z T ) is the solved translation vector;

[0025] Step S4: Construct the best fitting coordinate system ( XYZ2 ), and then transform the gravity coordinate system (O XYZ1 ) Coordinates of all points where the aircraft landed (X 1 , Y 1 , Z 1 ) to the fitting coordinate system (O XYZ2 ) to obtain the fitted point coordinates (X 2 , Y 2 , Z 2 ), so that the fitting results are more in line with the actual situation and can identify the global deformation;

[0026]

[0027] In order to better implement the present invention, further, in step S31, in order to reduce process iterations, when performing horizontal measurement on the aircraft, λ=1.

[0028] In order to better implement the present invention, further, in step S1, in the theoretical coordinate system ( XYZ0 ), select two lateral reference leveling points 1L and 1R on the rigid position surface close to the landing gear and symmetrically on the left / right wings; in the theoretical coordinate system (O XYZ0 ), select two longitudinal reference leveling points A and B on the fuselage, at the frame beam near the leading edge of the wing.

[0029] In order to better implement the present invention, further, two transverse reference leveling points are selected within 0.5m around the frame and beam; two longitudinal reference leveling points are selected within 0.5m around the frame beam on the fuselage close to the leading edge of the wing.

[0030] In order to better implement the present invention, further, in the step S2, when lateral leveling, the height of the left / right landing gear is adjusted, and the gravity direction coordinates of point 1L and point 1R are repeatedly observed, and the lateral level adjustment target is: the height difference between point 1L and point 1R is ±Emm, and E is the design allowable error. Specifically, the height difference between point 1L and point 1R is Hmm±Emm, because point 1L and point 1R are symmetrical, where H is 0, and E is the error allowed by the designer, which can generally be 0.5.

[0031] In order to better implement the present invention, further, in step S2, when adjusting the front landing gear in the longitudinal leveling, the gravity direction coordinates of point A and point B are repeatedly observed, and the longitudinal level adjustment target is: the height difference between point A and point B is Jmm±Emm, J represents the theoretical height difference between point A and point B, which is given by digital analog measurement; E is the design allowable error. Specifically, E is the error allowed by the designer, which can generally be 0.5.

[0032] In order to better implement the present invention, further, in the step S2, before the horizontal measurement, a status check is carried out in comparison with the theoretical digital analog status to ensure that there are no factors affecting the horizontal measurement and to keep no significant air flow near the aircraft.

[0033] In order to better implement the present invention, further, in step S4, by comparing the best fitting coordinate system ( XYZ2 ) points (X 2 , Y 2 , Z 2 ) and the theoretical coordinate system (O XYZ0 ) points (X 0 , Y 0 , Z 0 ) to obtain the absolute deformation.

[0034] The beneficial effects of the present invention are as follows:

[0035] (1) The present invention combines engineering practice to establish and systematically refine a set of methods for horizontal measurement of flexible large aspect ratio aircraft. The traditional fitting method does not consider the influence of large flexible deformation, resulting in a large deviation from the actual effect after calculation and fitting. In order to make up for the shortcomings of the prior art and reduce the deviation of flexible aircraft measurement data analysis, the present invention starts from isolating inherent deformation and proposes a weighted fitting method in the process of aircraft horizontal measurement, with the goal of reducing the overall fitting deviation, making the fitting result more in line with the actual situation, and enabling more accurate horizontal measurement.

[0036] (2) The present invention has been used to conduct a large number of tests on solar drones, hydrogen-powered drones, unmanned gliders, etc. Through comparative analysis, the processed results are consistent with the actual situation, providing an important basis for the precise control of large aspect ratio flexible drones. The present invention takes into account the impact caused by deformation, and its ideas can be extended to the measurement of other large flexible objects and wide-area geographical landforms, which is conducive to precise mapping. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a flow chart of a method for horizontal measurement of a large aspect ratio flexible aircraft.

[0038] Figure 2 It is a schematic diagram of the locations of key fitting feature points;

[0039] Figure 3 for Figure 2 Bottom view of the key fitting feature points;

[0040] Figure 4 The schematic diagram is for adjusting the height of the front and main landing gears respectively by using a lifting tray;

[0041] Figure 5 It is the position information of the key fitting feature points measured in the gravity coordinate system;

[0042] Figure 6 It is a fitting schematic diagram of each point in Example 1. DETAILED DESCRIPTION

[0043] Embodiment 1:

[0044] A method for measuring the level of a flexible aircraft with a large aspect ratio, such as Figure 1 As shown, the specific steps are as follows:

[0045] a) Clarify the purpose of horizontal measurement of large aspect ratio aircraft: focus on checking the symmetry of the aircraft. For flexible large aspect ratio aircraft, it is necessary to focus on measuring and checking the symmetry of the wing under symmetrical loading. In order to eliminate the influence of deformation near the landing gear or fulcrum position during the wing support process, the key fitting points are set at relatively rigid points near the connection area between the wing and the landing gear (such as near the frame or beam). The height difference of the key fitting points of the wing symmetry needs to be kept the same during measurement;

[0046] b) Selection and marking of key fitting feature points for lateral leveling of aircraft: Since the main purpose of the measurement is to predict the symmetry of the aircraft in the air, the key observation target is the wing. During the static inspection at the stop, in order to eliminate the influence of tire displacement on wing symmetry as much as possible during the leveling stage, two lateral reference leveling points are set on the surface of the rigid position symmetrical to the left / right wings (selected within 0.5m of the frame and beam), close to the landing gear, such as Figure 2 and Figure 3 As shown, the theoretical coordinate system (O XYZ0 )Next, click point 1L and point 1R.

[0047] c) Selection and marking of key fitting feature points for longitudinal leveling of aircraft: To ensure safety during parking, the longitudinal position of the center of gravity of the entire aircraft should be adjusted as horizontally as possible. Therefore, for longitudinal leveling of flexible aircraft, the solution is to set two longitudinal reference leveling points on the fuselage within 0.5m near the frame beam near the leading edge of the wing, such as Figure 2 and Figure 3 As shown, the theoretical coordinate system (O XYZ0 )Click point A and point B.

[0048] d) Confirmation of physical state: Before horizontal measurement, conduct a state check against the theoretical digital model state to ensure that there are no factors that affect the horizontal measurement. Take measures such as closing doors and windows, air conditioners, and fans to ensure that there is no significant air flow near the aircraft. Figure 4 As shown, the heights of the front and main landing gears are adjusted respectively by using tools such as a lifting tray.

[0049] e) Use laser tracker to build the station and establish the original gravity coordinate system (O XYZ1 ) so that the direction of gravity coincides with the Z direction;

[0050] f) Horizontal and longitudinal leveling: Use the lifting tray to adjust the height of the left / right landing gear, repeatedly observe the gravity direction coordinates of point 1L and point 1R, and adjust the horizontal level target: the difference between point 1L'(Z) and point 1R'(Z) is 0mm±XXmm; use the lifting tray to adjust the height of the front landing gear, such as Figure 5 As shown, repeatedly observe the gravity direction coordinates of point A and point B, and adjust the longitudinal level to the target: the difference between point A'(Z) and point B'(Z) is XXmm±XXmm.

[0051] g) measure the gravity coordinate system (O) XYZ1 ) The positions of various points on the lower fuselage, wings and tail.

[0052] h) Based on the least squares fitting method, the difference in gravity direction between point 1L (or point 1R) and point A (or point B) caused by the flexible deformation with large aspect ratio is isolated, and the weights (P X P Y P Z ), see Table 1; prepare to use formula (1) to construct the best fit (O XYZ2 ), where λ is the scale parameter, R is the rotation parameter matrix and T is the translation parameter.

[0053]

[0054] i) When using the least squares iteration method for coordinate transformation, the scale parameter λ is first solved. According to the set weight, the theoretical coordinate system (O XYZ0 ) are processed by gravity centering. Similarly, the gravity coordinate system (O XYZ1 ) are subjected to barycentric processing and converted into barycentric coordinates with their respective barycenters as the origins. The scale parameter λ is calculated according to formula (3). To reduce process iterations, when performing horizontal measurement of the aircraft, λ can be approximately considered to be 1.

[0055]

[0056] j) The rotation parameter matrix R is a third-order orthogonal matrix, and |R| = 1, then R can be expressed as formula (4) through the parameters containing a, b, and c, and substituted into the theoretical coordinate system (O XYZ0 ) and the gravity coordinate system (O XYZ1 ) to obtain the centroidal coordinates of the key fitting points, and then obtain the equations (5) and (6) after the centroidal coordinates of the key fitting points. According to the equation (7), a, b, c can be calculated, and then R can be obtained by the equation (4).

[0057]

[0058]

[0059] k) The translation parameter T can be obtained from formula (8).

[0060]

[0061] l) According to the scale parameter λ, the rotation parameter matrix R and the translation parameter T, the gravity coordinate system (O XYZ1 ) to the coordinates of all points of the aircraft under the fitting coordinate system, and obtain the coordinates of all points after fitting (X 2 Y 2 Z 2 ).

[0062]

[0063] m) More, by comparing the points (X 2 Y 2 Z 2 ) and (X 0 Y 0 Z 0 ) difference, and the absolute deformation is obtained.

[0064] As shown in Table 2, more can provide real point information for determining the center of gravity of the aircraft.

[0065] As shown in Tables 1 and 2, horizontal measurement and weight fitting are performed on a hydrogen-powered UAV to obtain the coordinate information of all points; Figure 6 As shown, based on the present invention, more than 130 horizontal measurement points on a UAV are measured. Compared with the traditional method for deviation analysis, the mean square error after statistical activities can be effectively reduced, which reduces the deviation of flexible aircraft measurement data analysis and is more in line with the actual situation. After practical verification, the method mentioned in the present invention is reliable and has practical value.

[0066] Table 1 Setting weights when fitting key feature points

[0067]

[0068] Table 2 Comparison of data records after point fitting

[0069]

[0070]

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for measuring the level of a flexible aircraft with a large aspect ratio, characterized in that: The following steps are involved: Step S1: In the theoretical coordinate system (O XYZ0 ), symmetrical key fitting points are selected in the lateral and longitudinal directions of the aircraft respectively as the lateral reference leveling points and the longitudinal reference leveling points of the aircraft; the key fitting points are the rigid points of the connection area between the wing and the landing gear; Step S2: Use the laser tracker to build the station and establish the original gravity coordinate system (O XYZ1 ), and its Z-axis direction coincides with the gravity direction; then, horizontal leveling and vertical leveling are performed based on the horizontal reference leveling point and the vertical reference leveling point respectively; Step S3: measure the gravity coordinate system (O XYZ1 ) The positions of the fuselage, wing and tail points are calculated; then, based on the least squares fitting method, the differences in the gravity direction between point 1L, point 1R, point A and point B caused by the flexible deformation of the large aspect ratio are isolated, and the scale parameter λ, rotation parameter matrix R and translation parameter T calculated are fitted to construct the best fitting coordinate system (O XYZ2 ): Where: (X1, Y1, Z1) is the gravity coordinate system (O XYZ1 ) below; (X2, Y2, Z2) is the best fitting coordinate system ( XYZ2 ) below; Step S31: first solve the scale parameter λ; According to the set weight (P X , P Y , P Z ), using formula (2) to calculate the theoretical coordinate system (O XYZ0 ) are processed by gravity centering. Similarly, the gravity coordinate system (O XYZ1 ) are subjected to barycentric processing and converted into barycentric coordinates with their respective barycenters as the origins. Then, the scale parameter λ is calculated according to formula (3): Among them: (X0, Y0, Z0) is the theoretical coordinate system ( XYZ0 ) below; is the theoretical coordinate system (O XYZ0 ) is the average value of the coordinates of each key fitting point; is the gravity coordinate system (O XYZ1 ) is the average value of the coordinates of each key fitting point; Step S32: solving the rotation parameter matrix R; The rotation parameter matrix R is a third-order orthogonal matrix, and |R| = 1, then R is expressed as formula (4) through parameters containing a, b, and c, and is respectively brought into the theoretical coordinate system (O XYZ0 ) and the gravity coordinate system (O XYZ1 ) to obtain the barycentric coordinates of the key fitting points, and then obtain the equations (5) and (6) after the barycentricity of the key fitting points. According to the equation (7), a, b, and c can be calculated, and then R can be obtained from the equation (4): Step S33: solving the translation parameter T; Where: (X T , Y T , Z T ) is the solved translation vector; Step S4: Construct the best fitting coordinate system ( XYZ2 ), and then transform the gravity coordinate system (O XYZ1 ) All the coordinates of the aircraft points (X1, Y1, Z1) are transferred to the fitting coordinate system (O XYZ2 ) to obtain the fitted point coordinates (X2, Y2, Z2) so that the fitted result is more consistent with the actual situation to identify the global deformation; 2. The method for measuring the level of a flexible aircraft with a large aspect ratio according to claim 1, characterized in that: In step S31, in order to reduce process iterations, when performing horizontal measurement on the aircraft, λ=1.

3. The method for measuring the level of a flexible aircraft with a large aspect ratio according to claim 1, characterized in that: In the step S1, in the theoretical coordinate system ( XYZ0 ), select two lateral reference leveling points 1L and 1R on the rigid position surface close to the landing gear and symmetrically on the left / right wings; in the theoretical coordinate system (O XYZ0 ), select two longitudinal reference leveling points A and B on the fuselage, at the frame beam near the leading edge of the wing.

4. The method for measuring the level of a flexible aircraft with a large aspect ratio according to claim 3 is characterized in that: Select two transverse reference leveling points within 0.5m around the frame and beam; select two longitudinal reference leveling points within 0.5m around the frame beam on the fuselage close to the leading edge of the wing.

5. The method for measuring the level of a flexible aircraft with a large aspect ratio according to claim 3 is characterized in that: In step S2, during lateral leveling, the height of the left / right landing gear is adjusted, and the gravity direction coordinates of point 1L and point 1R are repeatedly observed. The lateral level adjustment target is: the height difference between point 1L and point 1R is ±E mm, and E is the design allowable error.

6. The method for measuring the level of a flexible aircraft with a large aspect ratio according to claim 5, characterized in that: In step S2, during longitudinal leveling, the height of the front landing gear is adjusted, and the gravity direction coordinates of point A and point B are repeatedly observed. The longitudinal horizontal adjustment target is: the height difference between point A and point B is Jmm±Emm, where J represents the theoretical height difference between point A and point B, which is given by digital analog measurement; and E is the design allowable error.

7. A method for measuring the level of a flexible aircraft with a large aspect ratio according to any one of claims 1 to 6, characterized in that: In step S2, before the horizontal measurement, a status check is performed in comparison with the theoretical digital model status to ensure that there are no factors affecting the horizontal measurement and to ensure that there is no significant air flow near the aircraft.

8. The method for measuring the level of a flexible aircraft with a large aspect ratio according to claim 1, characterized in that: In step S4, by comparing the best fitting coordinate system ( XYZ2 ) and the theoretical coordinate system ( XYZ0 ) under each point (X0, Y0, Z0) to obtain the absolute deformation.

Images