Method and device for measuring mass center of large non-cylindrical winged carrier

Abstract

The invention provides a method and equipment for measuring the mass center of a large non-cylindrical winged carrier. The method comprises the following steps that a front vehicle and a rear vehicle are used for supporting the front end and the rear end of a product respectively; weighing sensors are arranged on the front vehicle and the rear vehicle; obtaining center-of-mass coordinates of a front / rear vehicle of the product; the mass center coordinates of the front / rear vehicle of the product are synthesized by the mass center coordinates of the front / rear vehicle under the horizontal state of the product and the mass center coordinates of the front / rear vehicle under the inclined state of the product; according to the static moment balance principle, the mass center coordinate of the product is synthesized by the mass center coordinate of the front vehicle of the product, the mass of the front vehicle of the product measured by the weighing sensor, the mass center coordinate of the rear vehicle of the product and the mass of the rear vehicle of the product measured by the weighing sensor. The method is provided aiming at the characteristics that a large non-cylindrical winged vehicle is long in fuselage, large in wingspan, far in distance between the belly and the center line of the fuselage and incapable of carrying out mass center measurement in a rolling mode, the safety degree and the measurement precision can be improved, and the measurement cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of centroid measurement, and in particular relates to a method and device for measuring the centroid of a large non-cylindrical winged vehicle. Background Art

[0002] The relevant technologies of large launch vehicles are currently a research hotspot in various countries, and mass and center of mass are important parameters of large launch vehicles. Accurately measuring the coordinates of mass and center of mass can help improve the accuracy of the carrier's attitude control, thereby ensuring the carrier's precise entry into orbit; it can help optimize the payload layout and reduce launch costs.

[0003] First, according to the principle category, the current center of mass measurement methods are divided into three categories, namely computer simulation experiment method, time domain measurement method, and frequency domain measurement method. Among them, the time domain measurement method is divided into static measurement and dynamic measurement. Static measurement includes mechanical repositioning method, multi-point weighing method, and unbalanced torque method. Dynamic measurement includes compound pendulum method, rotation balance method, and moment of inertia method. Frequency domain measurement methods include mass line method and modal analysis method.

[0004] However, many existing methods of measuring the center of mass have the following disadvantages when measuring large-scale aircraft:

[0005] (1) Safety issues. Dynamic measurement methods are widely used in the inspection of small and medium-sized test pieces, such as the multi-wire pendulum method, unbalanced torque method, and compound pendulum method. However, since large-sized test pieces are usually large in size, some problems will be introduced during the dynamic measurement process. For example, the multi-wire pendulum method requires the test piece to be suspended and twisted, and the strength of the suspension wire will affect the movement.

[0006] (2) Low measurement accuracy. Dynamic methods such as the multi-line pendulum method and the compound pendulum method have low measurement accuracy when measuring large-sized test pieces, while the multi-point weighing method mainly uses mechanical positioning and requires the test piece to be measured in a specific posture. Due to the large mass of large-sized aircraft, it is difficult to ensure the positioning accuracy of a specific posture.

[0007] (3) The measurement equipment has poor versatility. Large-sized aircraft are usually assembled from different parts. The shapes and sizes of different aircraft models are different, and the existing measurement equipment is mostly model-specific, resulting in poor versatility of the equipment. The current measurement method with a certain degree of versatility adopts a fixed sensor solution, specifically setting several weighing sensors at specific locations on the ground. Multiple sensor positions need to be leveled before testing. Practice shows that this method has low accuracy.

[0008] (4) It is difficult to measure large-volume and irregular-shaped test pieces. Because large non-cylindrical winged vehicles are tens of meters long and have a wingspan of more than ten meters, they are irregular in shape, so it is impossible to use traditional equipment and methods to measure the center of mass. Summary of the invention

[0009] In view of this, the present invention aims to propose a method and equipment for measuring the center of mass of a large non-cylindrical winged vehicle based on fuselage lifting and tilting, so as to measure the center of mass of a large non-cylindrical winged vehicle with a long fuselage, a large wingspan, and a belly far from the center line of the fuselage.

[0010] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0011] A method for measuring the center of mass of a large non-cylindrical winged vehicle comprises the following steps:

[0012] Use the front and rear carts to support the front and rear ends of the product respectively; both the front and rear carts are equipped with weighing sensors;

[0013] Obtain the center of mass coordinates of the vehicle in front of the product and the vehicle behind the product; the center of mass coordinates of the vehicle in front of the product are synthesized by the center of mass coordinates of the vehicle in front of the product when the product is horizontal and the center of mass coordinates of the vehicle in front of the product when the product is tilted; the center of mass coordinates of the vehicle behind the product are synthesized by the center of mass coordinates of the vehicle in front of the product when the product is horizontal and the center of mass coordinates of the vehicle in back of the product when the product is tilted;

[0014] According to the principle of static moment balance, the center of mass coordinates of the front vehicle of the product and the mass of the front vehicle of the product measured by the weighing sensor, the center of mass coordinates of the rear vehicle of the product and the mass of the rear vehicle of the product measured by the weighing sensor are synthesized to obtain the center of mass coordinates of the product.

[0015] Furthermore, the synthesis method of the center of mass coordinates of the front / rear vehicle of the product includes:

[0016] In a horizontal state, the analytical expression of the first gravity line of the vehicle in front of / behind the product in the product coordinate system is calculated from the coordinates of the intersection of the first gravity line of the vehicle in front of / behind the product and the XOY plane of the product coordinate system, as well as the direction vector of the first gravity line in the product coordinate system;

[0017] In the tilted state, the analytical expression of the second gravity line of the vehicle in front of / behind the product in the product coordinate system is calculated from the coordinates of the intersection of the second gravity line of the vehicle in front of / behind the product and the XOY plane of the product coordinate system, as well as the direction vector of the second gravity line in the product coordinate system;

[0018] In the product coordinate system, the estimated value of the intersection coordinates of the analytical expressions of the first gravity line of the front / rear vehicle and the second gravity line of the front / rear vehicle is calculated to obtain the center of mass coordinates of the front / rear vehicle of the product.

[0019] Furthermore, the calculation method of the analytical expression of the gravity action line of the front / rear vehicle of the product is:

[0020] The coordinates of the load cell bearing point in the reference coordinate system are converted into the coordinates of the load cell bearing point in the sensor coordinate system, and the static moment balance equation is established to obtain the projection point of the product center of mass in the sensor coordinate system XOY plane, that is, the intersection of the gravity line of the front / rear vehicle of the product and the XOY plane of the sensor coordinate system;

[0021] It is known that the line of gravity passes through the intersection of the line of gravity of the vehicle in front of / behind the product and the XOY plane of the sensor coordinate system, and the direction vector of the line of gravity in the sensor coordinate system is known. The coordinate conversion matrix is ​​used to obtain the coordinates of the intersection of the line of gravity of the vehicle in front of / behind the product and the XOY plane of the sensor coordinate system, as well as the direction vector of the line of gravity in the product coordinate system;

[0022] The analytical expression of the gravity line of the vehicle in front of / behind the product is obtained from the coordinates of the intersection of the gravity line of the vehicle in front of / behind the product in the product coordinate system and the XOY plane of the sensor coordinate system, as well as the direction vector of the gravity line in the product coordinate system.

[0023] Furthermore, the calculation method of the center of mass coordinates of the front / rear vehicle of the product is:

[0024] If the first gravity line intersects with the second gravity line, the intersection of the first gravity line and the second gravity line is the center of mass coordinate of the front / rear vehicle of the product;

[0025] If the first gravity action line and the second gravity action line are skew lines, the midpoint of the common perpendicular line between the first gravity action line and the second gravity action line in the product coordinate system is calculated as the center of mass coordinate of the front / rear vehicle of the product;

[0026] If the first gravity line and the second gravity line are skew lines, the process of solving the coordinates of the center of mass of the front / rear vehicle of the product is:

[0027] Assume product coordinate system O P -X P Y P Z P The intersection point of the first gravity line L1 and the common vertical line is N1(x N1 ,y N1 , z N1 ), the intersection point of the second gravity line and the common vertical line is N2(x N2 ,y N2 , z N2 ), since the common perpendicular line is perpendicular to the first gravity line L1 and the second gravity line L2 respectively, the coordinates of the two intersection points N1 and N2 satisfy the following formula:

[0028]

[0029] Among them, m1， n 1， p1 represents the direction vector of the first gravity line L1; m 2， n 2， p2 represents the direction vector of the second gravity line L2, (x N1 ,y N1 , z N1 ) is the coordinate of the intersection of the first gravity line L1 and the common perpendicular line, (x N2 ,y N2 , z N2 ) is the coordinate of the intersection of the first gravity line L2 and the common perpendicular line;

[0030] Since the two intersection points N1 and N2 are on the first gravity line L1 and the second gravity line L2 respectively, let

[0031]

[0032] in, Represents the coordinates of the projection point of the first gravity line of the product's center of mass in the product coordinate system. Represents the coordinates of the projection point of the second gravity line of the product's center of mass in the product coordinate system, k1 and k2 are the slopes of the two lines to be solved;

[0033] By combining the two variables k1 and k2, we can get a quadratic equation. By solving the equation, we can get the values ​​of k1 and k2, and find the foot coordinate N1 (x N1 ,y N1 , z N1 )、N2(x N2 ,y N2 , z N2 ), then the coordinates of the midpoints of the N1 and N2 segments are the centroid coordinates; the product coordinate system O P -X P Y P Z P The coordinates of the center of mass of the front / rear vehicle of the next product are:

[0034]

[0035] Among them, (xP cg ,yP cg , zP cg ) is the product coordinate system O P -X P Y P Z P Further, according to the principle of static moment balance, the method of synthesizing the center of mass coordinates of the front vehicle of the product and the mass of the front vehicle of the product measured by the weighing sensor, the center of mass coordinates of the rear vehicle of the product and the mass of the rear vehicle of the product measured by the weighing sensor to obtain the center of mass coordinates of the product is:

[0036] The center of mass of the front vehicle of the product is CG 前 , the product mass measured by the front vehicle is M 前 , the center of mass of the rear vehicle is CG 后 , the product mass measured by the rear vehicle is M 后 , according to the principle of static moment balance, the center of mass coordinates of the product are synthesized:

[0037] Among them, M 前 is the mass measured by the preceding vehicle, M 后 is the mass measured by the rear vehicle, and the center of mass coordinates of the front vehicle in the product coordinate system are The coordinates of the center of mass of the rear vehicle in the product coordinate system are: Combined to obtain the coordinates of the center of mass of the arrow (x P ,y P , z P ).

[0038] Furthermore, the coordinate system conversion method is:

[0039] The coordinate system of the laser tracker is defined as a reference coordinate system; the laser tracker is used to determine the relative position of the product to be tested and the front / rear vehicle;

[0040] Select the three target seats on the periphery of the front / rear vehicle base as reference points to establish a reference coordinate system;

[0041] Using the reference coordinate system as an intermediate bridge, calculate the conversion matrix between the sensor coordinate system of the front / rear vehicle and the reference coordinate system, and the conversion matrix between the reference coordinate system of the front / rear vehicle and the product coordinate system, and then obtain the conversion matrix between the sensor coordinate system of the front / rear vehicle and the product coordinate system;

[0042] The sensor coordinate system is established as follows: weighing sensors are set at the four corners of the front and rear vehicles; the geometric center of the bearing points of the four weighing sensors is taken as the origin O S , X S The axis is from the origin O S Point to the midpoint of the line connecting the bearing points of two adjacent load cells, Z S The axis is perpendicular to the plane where the bearing points of the four load cells are located and points upward. S Determine by the right-hand rule, that is, X S The axis passes through the palm of the right hand, with the thumb pointing to Z S axis, the four fingers point to the Y S axis;

[0043] The method for establishing the product coordinate system is as follows: the origin O p : Located at the theoretical apex of the nose; X p Axis: Located in the carrier's symmetry plane, passing through the coordinate origin Op The normal of the vertical reference plane is positive when it points to the rear of the aircraft; p Axis: Located in the carrier's symmetry plane, perpendicular to the X p Axis, pointing to the back of the body is positive; Z p Axis: Determined by the right-hand rule, i.e. X p The axis passes through the palm of the right hand, with the thumb pointing to the Y p axis, then the four fingers point to Z p Axis; the rear end face of the vehicle is defined as the vertical reference plane.

[0044] A large non-cylindrical winged carrier mass center measuring device includes a front vehicle for supporting the front end of the product and a rear vehicle for supporting the rear end of the product. Both the front vehicle and the rear vehicle include a measuring vehicle and a supporting tooling carried on the measuring vehicle. A weighing sensor is arranged in the measuring vehicle, and the supporting tooling is carried on the weighing sensor.

[0045] There are four weighing sensors, which are respectively set at the four corners of the measuring carriage; the front carriage and the rear carriage are both set on the guide rails, and can move closer or farther away from each other along the guide rails; the top of the supporting tooling is U-shaped to facilitate the positioning of the measured piece; there are also anti-bias lifting devices on the four corners of the measuring carriage to adjust the height of the supporting tooling;

[0046] The measuring equipment also includes an anti-overturning support and protection platform, which is arranged in a fence-like manner around the outer periphery of the measuring vehicle, and four jacks are installed on its four columns; when the product is installed, the jacks are pressed against the bottom of the supporting tooling; when the product is measured, the top surface of the jacks descends and separates from the supporting tooling.

[0047] An electronic device comprises a processor and a memory which is in communication with the processor and is used to store instructions executable by the processor. The processor is used to execute the above-mentioned method for measuring the center of mass of a large non-cylindrical winged vehicle.

[0048] A server includes at least one processor and a memory in communication with the processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor to enable the at least one processor to perform the above-mentioned method for measuring the center of mass of a large non-cylindrical winged vehicle.

[0049] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned method for measuring the center of mass of a large non-cylindrical winged vehicle.

[0050] Compared with the prior art, the method and device for measuring the center of mass of a large non-cylindrical winged vehicle created by the present invention have the following advantages:

[0051] The invention creates a method and device for measuring the center of mass of a large non-cylindrical winged vehicle. The method is proposed for measuring the center of mass of a large non-cylindrical winged vehicle, which has a long fuselage, a large wingspan, and a belly far from the center line of the fuselage, and cannot be measured by rolling. The method is a method for measuring the center of mass based on the lifting and tilting of the fuselage, and solves the following problems:

[0052] (1) Improve safety. The center of mass detection is a multi-point weighing method in static detection. In actual operation, measures such as jacks are used to prevent risks.

[0053] (2) Improve measurement accuracy. The dynamic detection method has low accuracy. The multi-point weighing method helps the sensor obtain accurate values. The data is processed by the centroid detection algorithm to obtain more accurate three-dimensional coordinates of the center of mass.

[0054] (3) Reduce detection costs and provide important parameter support for the attitude control and payload configuration of subsequent launch vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0056] Figure 1 A schematic diagram of a physical model of a mass center of mass flexible measurement system of a method for measuring the center of mass of a large non-cylindrical winged vehicle according to an embodiment of the present invention is shown;

[0057] Figure 2 The actual installation of the equipment sensor of the method for measuring the center of mass of a large non-cylindrical winged vehicle according to the embodiment of the invention is shown;

[0058] Figure 3 A schematic diagram of the coordinate system of the entire aircraft is shown for a method for measuring the center of mass of a large non-cylindrical winged vehicle according to an embodiment of the present invention;

[0059] Figure 4 A schematic diagram showing the quadrant definition of the tank area from the rear to the front of the method for measuring the center of mass of a large non-cylindrical winged vehicle according to an embodiment of the invention is shown;

[0060] Figure 5 The schematic diagram of the coordinate conversion algorithm of the method for measuring the center of mass of a large non-cylindrical winged vehicle according to the embodiment of the invention is shown;

[0061] Figure 6 The overall structural schematic diagram of the large non-cylindrical winged vehicle center of mass measurement device according to the embodiment of the invention is shown;

[0062] Figure 7A schematic diagram of the internal structure of the front and rear vehicles of a large non-cylindrical winged vehicle mass center measuring device according to an embodiment of the present invention is shown;

[0063] Figure 8 A schematic diagram showing a product level measurement state of a large non-cylindrical winged vehicle mass center measurement device according to an embodiment of the present invention is shown;

[0064] Fig. 9 A schematic diagram of a product tilt measurement state of a large non-cylindrical winged vehicle mass center measurement device according to an embodiment of the present invention is shown;

[0065] Fig.10 A schematic diagram of the structure of the front end anti-overturning support protection platform of the large non-cylindrical winged vehicle center of mass measurement device according to the embodiment of the invention is shown;

[0066] Fig.11 A schematic diagram of the structure of the rear end anti-overturning support protection platform of the large non-cylindrical winged vehicle center of mass measurement device according to the embodiment of the invention is shown;

[0067] Fig.12 A schematic structural diagram of the preparation stage of the large non-cylindrical winged vehicle mass center measurement device according to an embodiment of the present invention is shown;

[0068] Fig.13 It shows a schematic structural diagram of a product level measurement stage of a large non-cylindrical winged vehicle mass center measurement device according to an embodiment of the present invention;

[0069] Fig.14 A schematic structural diagram of the product tilt measurement phase of the large non-cylindrical winged vehicle mass center measurement device described in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0070] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0071] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0072] 1. Measurement principle

[0073] The physical model of the center of mass flexible measurement system is as follows Figure 1As shown, the so-called flexible measurement method means that the measurement system consists of two relatively independent measurement subsystems, the front car and the rear car. The measuring frame is placed on the linear guide rail on site. Each subsystem uses 4 high-precision weighing sensors to support the upper measurement platform, that is, the supporting tooling. The tooling, appearance of the subsystem and the relative distance between the two subsystems can be changed according to the different sizes of the measured parts. The measurement system has strong compatibility and can ensure the safety and stability of the measurement process. The laser tracker is used to measure the positional relationship between the two subsystems and the positional relationship between the subsystem and the measured part. Combined with the measurement value of the weighing sensor, the mass and three-dimensional center of mass of the measured part can be obtained. The actual installation of the weighing sensor of this system is shown in the figure. Figure 2 .

[0074] The measurement process is described using the previous car as an example.

[0075] In the first measurement state, the product to be measured is in a horizontal position. The product is measured to obtain the intersection coordinates of the first gravity line of the front vehicle and the XOY plane of the sensor coordinate system in the sensor coordinate system and the direction vector of the first gravity line.

[0076] By using the conversion relationship between the sensor coordinate system and the reference coordinate system, and the conversion relationship between the reference coordinate system and the product coordinate system, the coordinates of the intersection of the first gravity line of the front vehicle and the XOY plane of the sensor coordinate system and the direction vector of the first gravity line in the product coordinate system are obtained, and then the analytical expression of the first gravity line in the product coordinate system is obtained.

[0077] Tilt the product 12° to place it in the second measurement state, measure the product, and obtain the coordinates of the intersection of the second gravity line of the front vehicle and the XOY plane of the sensor coordinate system and the direction vector of the second gravity line in the sensor coordinate system.

[0078] By using the conversion relationship between the sensor coordinate system and the reference coordinate system, and the conversion relationship between the reference coordinate system and the product coordinate system, the intersection coordinates of the second gravity line of the front vehicle in the product coordinate system and the XOY plane of the sensor coordinate system and the direction vector of the second gravity line are obtained, and then the analytical expression of the second gravity line in the product coordinate system is obtained.

[0079] Finally, the estimated coordinates of the intersection of the two gravity lines of the front vehicle in the product coordinate system are obtained, that is, the coordinates of the center of mass of the front vehicle of the product.

[0080] In the process of measuring the center of mass coordinates of the front vehicle, the rear vehicle synchronously completes all the steps of measuring the front vehicle, and obtains the center of mass coordinates of the rear vehicle of the product.

[0081] The center of mass coordinates measured by the front and rear vehicles are synthesized to obtain the final center of mass coordinates of the product.

[0082] The centroid calculation process involves multiple coordinate systems, which are defined as follows:

[0083] O S -X S Y S Z S The sensor coordinate system is composed of the four load cells on the base of the measuring vehicle. i (i=1,2,3,4) to determine, take the geometric center of the bearing points of the four weighing sensors as the origin O S , X S The axis is from the origin O S Point to the midpoint of the line connecting the third load cell bearing point S3 and the fourth load cell bearing point S4, Z S The axis is perpendicular to the plane where the four points are located and points upward, S Determine by the right-hand rule, that is, X S The axis passes through the palm of the right hand, with the thumb pointing to Z S axis, the four fingers point to the Y S The measurement system consists of two measurement subsystems on the front and rear vehicles. The coordinate system determined by the coordinates of the four load cells on the front vehicle is called the front vehicle sensor coordinate system. S1 -X S1 Y S1 Z S1 The coordinate system determined by the coordinates of the four load cells on the rear vehicle is called the rear vehicle sensor coordinate system O S2 -X S2 Y S2 Z S2 .

[0084] O P -X P Y P Z P It is the product coordinate system, that is, the full-machine coordinate system of the large non-cylindrical winged carrier in this implementation, which is specified by the product designer, and the final measurement results of the three-dimensional center of mass are all expressed in the product coordinate system.

[0085] The whole machine coordinate system described in this embodiment is defined as follows:

[0086] Origin O: located at the theoretical vertex of the nose. The actual vertex of the nose refers to the farthest point of the intersection of the carrier's symmetry plane and the fuselage's outer surface from the vertical reference plane. The actual vertex of the nose is consistent with the theoretical vertex, and its coordinates in the full aircraft coordinates are (0, 0, 0);

[0087] X-axis: located in the carrier's symmetry plane, it is the normal of the vertical reference plane passing through the coordinate origin O, and is positive when it points to the rear of the vehicle;

[0088] Y axis: located in the carrier's symmetry plane, perpendicular to the X axis, and pointing to the back of the vehicle;

[0089] Z axis: Determined by the right-hand rule, that is, the X axis passes through the palm of the right hand, the thumb points to the Y axis, and the four fingers point to the Z axis;

[0090] The tail end face of the carrier is defined as the vertical reference plane, and the whole aircraft coordinate system OXYZ is as follows Figure 3 shown.

[0091] The definition of the large non-cylindrical winged launch vehicle tank area quadrant is as follows: Figure 4 (Read from back to front).

[0092] In order to determine the relative position between the product to be tested and the measuring device, a laser tracker is introduced to measure the coordinates of key points. For the convenience of description, the coordinate system of the laser tracker is defined as the reference coordinate system O L -X L Y L Z L .

[0093] In order to determine the position of the weighing sensor in product measurement, three target seats on the periphery of the measuring vehicle base are selected as reference points C i (i=1,2,3), used to establish the reference coordinate system O C -X C Y C Z C . Take the geometric center of the three reference points as the origin O C , X C The axis is from the origin O C Point to the first reference point C1, Z C The axis is perpendicular to the plane where the three points are located and points upward, C Determine by the right-hand rule, that is, X C The axis passes through the palm of the right hand, with the thumb pointing to Z C axis, the four fingers point to the Y C axis.

[0094] The conversion between coordinate systems is usually achieved through rotation and translation, and its conversion algorithm is usually implemented with the help of matrix operations. Suppose the coordinates of a point A in the space in the N coordinate system are (x N ,y N ,z N ), the coordinates in the M coordinate system are (x M ,y M ,z M ), the transformation matrix between the N coordinate system and the M coordinate system is T NM , then the following relationship exists between the two coordinate systems:

[0095]

[0096] Transformation Matrix T NMIt can be expressed as:

[0097]

[0098] Where R NM ——Rotation matrix from N coordinate system to M coordinate system;

[0099] C NM ——Translation vector from N coordinate system to M coordinate system.

[0100] The key to the coordinate transformation algorithm is to calculate the rotation matrix and translation vector between the two coordinate systems. Figure 5 As shown in FIG. 1 , since the positioning points used to establish the coordinate system are initially described in the reference coordinate system, the front vehicle sensor coordinate system O can be calculated using the reference coordinate system as the intermediate bridge. S1 -X S1 Y S1 Z S1 With the front vehicle reference coordinate system O R1 -X R1 Y R1 Z R1 , the front vehicle reference coordinate system O R1 -X R1 Y R1 Z R1 With product coordinate system O P -X P Y P Z P The conversion matrix between them is then used to obtain the front vehicle sensor coordinate system O S1 -X S1 Y S1 Z S1 With product coordinate system O P -X P Y P Z P The transformation matrix.

[0101] Similarly, the sensor coordinate system of the rear vehicle can be calculated using the reference coordinate system as the middle bridge. S2 -X S2 Y S2 Z S2 With the following vehicle reference coordinate system O R2 -X R2 Y R2 Z R2 , the following vehicle reference coordinate system O R2 -X R2 Y R2 Z R2 With product coordinate system O P -X P Y P Z PThe transformation matrix between them is then used to obtain the rear vehicle sensor coordinate system O S2 -X S2 Y S2 Z S2 With product coordinate system O P -X P Y P Z P The transformation matrix.

[0102] 2. Calculation process:

[0103] First, carry out no-load measurement, at which time the mass of the supporting tooling is measured:

[0104]

[0105] Where M0 is the mass of the supporting tooling;

[0106] m 0i (i=1,2,...,8)——Measurement values ​​of 8 weighing sensors during no-load measurement.

[0107] Load the test piece, record the current measurement values ​​of the 8 weighing sensors and the measurement posture of the test piece, and obtain the total mass of the support fixture and the test piece:

[0108]

[0109] Where M1 is the total mass of the supporting fixture and the tested object;

[0110] m 1i (i=1,2,...,8)——Measurement values ​​of 8 weighing sensors after loading the test piece.

[0111] The mass of the measured object can be obtained by subtracting the two equations:

[0112]

[0113] Where M is the mass of the tested piece;

[0114] Δm i ——Measurement values ​​of 8 weighing sensors before and after loading the test piece.

[0115] The calculation of the center of mass is still explained using the front car as an example, and then the center of mass calculated by the front car and the rear car are combined. The parameters required to establish the three-dimensional center of mass calculation model of the front car are as follows:

[0116] Table 1. Relevant parameters for establishing the three-dimensional centroid calculation model

[0117]

[0118] Describe the first gravity line L1 of the product in the product coordinate system, and determine the center of mass of the product in the X and Z directions when the product is in a horizontal position.

[0119] The coordinates of the load cell bearing point in the instrument coordinate system (i=1,2,3,4) After coordinate transformation, the coordinates of the load cell bearing point in the sensor coordinate system are obtained. (i=1,2,3,4), establish the static moment balance equation, and obtain the first gravity line L1 and the sensor coordinate system X in the measurement coordinate system. S O S Y S The intersection of the two surfaces, that is, the centroid of the product, is at X S O S Y S The projection point of the plane is denoted as CG1:

[0120] Projection point CG1 is at X S , Y S The coordinates of the axis directions are as follows.

[0121]

[0122] Since the first gravity line L1 passes through point CG1, and the direction vector of L1 in the sensor coordinate system is (0,0,1), the coordinate transformation matrix can be used to obtain the coordinates of the projection point CG1 in the product coordinate system.

[0123] The direction vector (m1, n1, p1) of L1 in the product coordinate system.

[0124]

[0125] Therefore, the analytical expression of product L1 in the product coordinate system is:

[0126]

[0127] Describe the second gravity line L2 of the product in the product coordinate system, and determine the center of mass of the product in the Y direction when the product is in an inclined state.

[0128] Known coordinates of the load cell bearing point in the sensor coordinate system (i=1,2,3,4), establish the static moment balance equation, and find the center of mass of the product at X S O S Y S The coordinates of the projection point of the surface in the measurement coordinate system are denoted as CG2:

[0129] The projection point is at XS , Y S The coordinates of the axis directions are as follows.

[0130]

[0131] Since the second gravity line L2 passes through point CG2, and the direction vector of L2 in the sensor coordinate system is (0,0,1), the coordinate transformation matrix can be used to obtain the coordinates of the projection point CG2 in the product coordinate system.

[0132] The direction vector of L2 in the product coordinate system (m2, n2, p2).

[0133]

[0134] Therefore, the analytical expression of L2 in the product coordinate system is:

[0135]

[0136] Calculate the center of mass CG of the vehicle in front of the product: When L1 and L2 intersect, the intersection between L1 and L2 is the center of mass, and the solution is relatively simple; when L1 and L2 are skew lines, it is necessary to calculate the midpoint of the common perpendicular line between L1 and L2 in the product coordinate system to obtain the best estimate of the center of mass. The solution process is as follows:

[0137] Assume that the intersection point of L1 and the common vertical line in the product coordinate system is N1(x N1 ,y N1 , z N1 ), the intersection point of L2 and the common perpendicular line is N2(x N2 ,y N2 , z N2 ), since the common perpendicular is perpendicular to L1 and L2 respectively, the coordinates of the two intersection points satisfy the following formula:

[0138]

[0139] Since the two intersection points are on L1 and L2 respectively, let

[0140]

[0141] By combining the two variables k1 and k2, we can get a quadratic equation. By solving the equation, we can get the values ​​of k1 and k2, and find the foot coordinate N1 (x N1 ,y N1 , z N1 )、N2(x N2 ,y N2 , z N2 ). The coordinates of the midpoint of the N1N2 line segment are the estimated coordinates of the centroid. P -X P Y P ZP The CG coordinates of the center of mass of the front vehicle in the next product are:

[0142]

[0143] The center of mass of the front vehicle of the product is CG 前 , the product mass measured by the front vehicle is M 前 , the center of mass of the rear vehicle is CG 后 , the product mass measured by the rear vehicle is M 后 , according to the principle of static moment balance, the center of mass coordinates of the product are synthesized:

[0144] Among them, M 前 is the mass measured by the preceding vehicle, M 后 is the mass measured by the rear vehicle, and the center of mass coordinates of the front vehicle in the product coordinate system are The coordinates of the center of mass of the rear vehicle in the product coordinate system are: Combined to obtain the coordinates of the center of mass of the arrow (x P ,y P , z P ).

[0145] 3. Measuring equipment

[0146] Mass center measurement equipment, see Figure 6 , including the front car and the rear car, used for the mass and transverse and longitudinal center of mass measurement of large non-cylindrical winged vehicles, including two sets of flexible and independent high-precision combined measurement cars (internal structure see Figure 7 ), front support tooling, rear support tooling, tilt measurement tooling, anti-overturning support protection platform, etc., among which, the support tooling is carried on the measuring car and supported by the weighing sensor in the measuring car; the top of the support tooling is U-shaped to facilitate the positioning of the measured part; anti-bias lifting devices are also provided on the four corners of the measuring car to adjust the height of the support tooling; a sensor position measurement point is set on the outer wall of the measuring car at a position opposite to the weighing sensor, which is used to measure the position of the weighing sensor.

[0147] The measuring equipment can be used with high-precision spatial coordinate measuring instruments (such as laser trackers) to accurately obtain the positional relationship between the two measuring trolleys and the positional relationship between the measuring trolley and the product, and accurately measure the mass and horizontal and vertical center of mass of the measured product. The system is also an integrated assembly and measurement platform. When the mass center of mass measurement is not being performed, it can be used to support the product and perform assembly work.

[0148] Measurement requirements:

[0149] It is required to be able to measure the landing gear in both retracted and extended states, with a mass measurement accuracy of 5kg (product weight is about 30t); the X, Y, and Z axis center of mass measurement accuracy is 5mm.

[0150] Measurement solution:

[0151] This section describes the measurement solution for large non-cylindrical winged carrier products, taking the landing gear down and the door open as an example:

[0152] (1) When the product is placed horizontally, the front / rear vehicle measures the mass of the carrier and the center of mass in the X and Z directions. Figure 8 shown.

[0153] (2) Place the product at a certain angle and measure the center of mass in the Y direction.

[0154] In order to measure the state of the vehicle after it tilts to a certain angle, the rear vehicle was replaced with a special rear support tooling for tilt measurement, and the front vehicle added a support tooling several meters high to the original horizontal measurement support tooling. At the same time, the front and rear vehicles were designed with anti-overturning support protection platforms to prevent danger caused by tooling tilt during product installation and measurement. The product status at this stage is as follows: Fig. 9 shown.

[0155] (3) Product and tooling support interface

[0156] Since the product needs to be tilted at a certain angle for measurement when measuring the Y-axis center of mass, it is necessary to use the lifting shaft at the front end of the product and the two fulcrums and supporting tooling at the front and rear ends of the product for positioning and connection.

[0157] (4) Anti-overturning support protection platform

[0158] The anti-overturning support protection platform is fenced around the measuring vehicle, and four hydraulic jacks are installed on its four columns. When the product is installed, the jack is pressed against the circular hole at the bottom of the support tooling to protect the support tooling and prevent the product from tilting during installation. When the product is measured, the support tooling and the product are in contact with the weighing sensor through the steel ball. At this time, to prevent the support tooling from accidentally tilting, the top surfaces of the four hydraulic jacks are lowered to a position about 2mm below the support tooling, which protects the product without affecting the product measurement. During the measurement process, the safety of the product is ensured by limit devices. At the same time, the measuring vehicle can move on the track by relying on wheels, which can ensure that the equipment itself is not damaged during the change of measurement location in the factory. See the front and rear anti-overturning support protection platforms. Fig.10 and Fig.11 .

[0159] Equipment installation tutorial

[0160] (1) Preparation

[0161] Prepare high-precision combined measuring vehicles, front support tooling, rear support tooling, tilt measuring tooling, anti-overturning support protection platform, etc., and place the two measuring vehicles on the guide rails to the appropriate position. Fig.12 , connect the control cabinet for preliminary debugging.

[0162] (2) Install the level measuring tool

[0163] Product level measuring tooling Fig.13 As shown in the figure, when measuring the level of the product, the front support tooling, anti-rollover protection platform, hydraulic jack, etc. on the front vehicle can be installed together on the measuring vehicle. If the bottom area of ​​the support tooling on the rear vehicle is smaller, the cross beams on both sides can be installed separately to support it between the jack and the rear support tooling. The anti-rollover protection platform on the rear vehicle can be installed after adjusting the distance between the two measuring vehicles before measuring the product tilt.

[0164] (3) Install the tilt measurement tool

[0165] After adjusting the distance between the front and rear vehicles, first install the rear vehicle anti-overturning support protection platform and hydraulic jack, and then install the rear support tooling. When installing the front support tooling, first remove the upper part that contacts the suspension shaft, install it on the top of the newly added front support tooling in the middle, and then connect the two sections of the support tooling to the bottom. The status of the tooling after installation is as follows: Fig.14 shown.

[0166] The embodiments of the present invention provide a method and device for measuring the center of mass of a large non-cylindrical winged vehicle. Because the center of mass position of a non-cylindrical winged test piece cannot be detected by the traditional rotation method, the existing mechanical structure, algorithm, and supporting software are optimized. Specifically, a supporting tool is added on the basis of the existing tooling, and the center of mass detection of the test piece in a fixed state is completed through the optimized algorithm. The present invention meets the needs of mass center of mass detection of large-volume irregular test pieces, improves the accuracy of mass center of mass detection of large-volume irregular test pieces, provides a solution for the detection of large-scale test instruments, and this achievement is currently at the forefront. And by upgrading the existing tooling, the center of mass measurement cost is reduced.

[0167] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0168] In the several embodiments provided in the present application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of the units described above is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. The above-mentioned units may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

[0170] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the center of mass of a large non-cylindrical winged vehicle, characterized in that: The steps include: Use the front and rear carts to support the front and rear ends of the product respectively; both the front and rear carts are equipped with weighing sensors; Obtain the center of mass coordinates of the vehicle in front of the product and the vehicle behind the product; the center of mass coordinates of the vehicle in front of the product are synthesized by the center of mass coordinates of the vehicle in front of the product when the product is horizontal and the center of mass coordinates of the vehicle in front of the product when the product is tilted; the center of mass coordinates of the vehicle behind the product are synthesized by the center of mass coordinates of the vehicle in front of the product when the product is horizontal and the center of mass coordinates of the vehicle in back of the product when the product is tilted; According to the principle of static moment balance, the center of mass coordinates of the front vehicle of the product and the mass of the front vehicle of the product measured by the weighing sensor, the center of mass coordinates of the rear vehicle of the product and the mass of the rear vehicle of the product measured by the weighing sensor are synthesized to obtain the center of mass coordinates of the product.

2. The method for measuring the center of mass of a large non-cylindrical winged vehicle according to claim 1, characterized in that: The synthesis method of the center of mass coordinates of the front / rear vehicle of the product includes: In a horizontal state, the analytical expression of the first gravity line of the vehicle in front of / behind the product in the product coordinate system is calculated from the coordinates of the intersection of the first gravity line of the vehicle in front of / behind the product and the XOY plane of the product coordinate system, as well as the direction vector of the first gravity line in the product coordinate system; In the tilted state, the analytical expression of the second gravity line of the vehicle in front of / behind the product in the product coordinate system is calculated from the coordinates of the intersection of the second gravity line of the vehicle in front of / behind the product and the XOY plane of the product coordinate system, as well as the direction vector of the second gravity line in the product coordinate system; In the product coordinate system, the estimated value of the intersection coordinates of the analytical expressions of the first gravity line of the front / rear vehicle and the second gravity line of the front / rear vehicle is calculated to obtain the center of mass coordinates of the front / rear vehicle of the product.

3. The method for measuring the center of mass of a large non-cylindrical winged vehicle according to claim 2, characterized in that: The calculation method of the analytical expression of the gravity line of the front / rear vehicle of the product is: The coordinates of the load cell bearing point in the reference coordinate system are converted into the coordinates of the load cell bearing point in the sensor coordinate system, and the static moment balance equation is established to obtain the projection point of the product center of mass in the sensor coordinate system XOY plane, that is, the intersection of the gravity line of the front / rear vehicle of the product and the XOY plane of the sensor coordinate system; It is known that the line of gravity passes through the intersection of the line of gravity of the vehicle in front of / behind the product and the XOY plane of the sensor coordinate system, and the direction vector of the line of gravity in the sensor coordinate system is known. The coordinate conversion matrix is ​​used to obtain the coordinates of the intersection of the line of gravity of the vehicle in front of / behind the product and the XOY plane of the sensor coordinate system, as well as the direction vector of the line of gravity in the product coordinate system; The analytical expression of the gravity line of the vehicle in front of / behind the product is obtained from the coordinates of the intersection of the gravity line of the vehicle in front of / behind the product in the product coordinate system and the XOY plane of the sensor coordinate system, as well as the direction vector of the gravity line in the product coordinate system.

4. The method for measuring the center of mass of a large non-cylindrical winged vehicle according to claim 2, characterized in that: The calculation method of the center of mass coordinates of the front / rear vehicle of the product is: If the first gravity line intersects with the second gravity line, the intersection of the first gravity line and the second gravity line is the center of mass coordinate of the front / rear vehicle of the product; If the first gravity action line and the second gravity action line are skew lines, the midpoint of the common perpendicular line between the first gravity action line and the second gravity action line in the product coordinate system is calculated as the center of mass coordinate of the front / rear vehicle of the product; If the first gravity line and the second gravity line are skew lines, the process of solving the coordinates of the center of mass of the front / rear vehicle of the product is: Assume product coordinate system O P -X P Y P Z P The intersection point of the first gravity line L1 and the common vertical line is N1(x N1 ,y N1 , z N1 ), the intersection point of the second gravity line and the common vertical line is N2(x N2 ,y N2 , z N2 ), since the common perpendicular line is perpendicular to the first gravity line L1 and the second gravity line L2 respectively, the coordinates of the two intersection points N1 and N2 satisfy the following formula: Among them, m 1， n 1， p1 represents the direction vector of the first gravity line L1; m 2， n 2， p2 represents the direction vector of the second gravity line L2, (x N1 ,y N1 , z N1 ) is the coordinate of the intersection of the first gravity line L1 and the common perpendicular line, (x N2 ,y N2 , z N2 ) is the coordinate of the intersection of the first gravity line L2 and the common perpendicular line; Since the two intersection points N1 and N2 are on the first gravity line L1 and the second gravity line L2 respectively, let in, Represents the coordinates of the projection point of the first gravity line of the product's center of mass in the product coordinate system. Represents the coordinates of the projection point of the second gravity line of the product's center of mass in the product coordinate system, k1 and k2 are the slopes of the two lines to be solved; By combining the two variables k1 and k2, we can get a linear equation. By solving the equation, we can get the values ​​of k1 and k2, and find the foot coordinate N1(x N1 ,y N1 , z N1 )、N2(x N2 ,y N2 , z N2 ), then the coordinates of the midpoints of the N1 and N2 segments are the centroid coordinates; the product coordinate system O P -X P Y P Z P The center of mass coordinates of the front / rear vehicle of the next product are: in, is the product coordinate system O P -X P Y P Z P The center of mass coordinates of the front / rear vehicle of the product.

5. The method for measuring the center of mass of a large non-cylindrical winged vehicle according to claim 1, characterized in that: According to the principle of static moment balance, the method of synthesizing the coordinates of the center of mass of the front vehicle of the product and the mass of the front vehicle of the product measured by the weighing sensor, the coordinates of the center of mass of the rear vehicle of the product and the mass of the rear vehicle of the product measured by the weighing sensor to obtain the coordinates of the center of mass of the product is: The center of mass of the front vehicle of the product is CG 前 , the product mass measured by the front vehicle is M 前 , the center of mass of the rear vehicle is CG 后 , the product mass measured by the rear vehicle is M 后 , according to the principle of static moment balance, the center of mass coordinates of the product are synthesized: Among them, M 前 is the mass measured by the preceding vehicle, M 后 is the mass measured by the rear vehicle, and the center of mass coordinates of the front vehicle in the product coordinate system are The coordinates of the center of mass of the rear vehicle in the product coordinate system are: Combined to obtain the coordinates of the center of mass of the arrow (x P ,y P , z P ).

6. The method for measuring the center of mass of a large non-cylindrical winged vehicle according to claim 2, characterized in that: The coordinate system conversion method is: The coordinate system of the laser tracker is defined as a reference coordinate system; the laser tracker is used to determine the relative position of the product to be tested and the front / rear vehicle; Select the three target seats on the periphery of the front / rear vehicle base as reference points to establish a reference coordinate system; Using the reference coordinate system as an intermediate bridge, calculate the conversion matrix between the sensor coordinate system of the front / rear vehicle and the reference coordinate system, and the conversion matrix between the reference coordinate system of the front / rear vehicle and the product coordinate system, and then obtain the conversion matrix between the sensor coordinate system of the front / rear vehicle and the product coordinate system; The sensor coordinate system is established as follows: weighing sensors are set at the four corners of the front and rear vehicles; the geometric center of the bearing points of the four weighing sensors is taken as the origin O S , X S The axis is from the origin O S Point to the midpoint of the line connecting the bearing points of two adjacent load cells, Z S The axis is perpendicular to the plane where the bearing points of the four load cells are located and points upward. S Determine by the right-hand rule, that is, X S The axis passes through the palm of the right hand, with the thumb pointing to Z S axis, then the four fingers point to the Y S axis; The method for establishing the product coordinate system is as follows: the origin O p : Located at the theoretical apex of the nose; X p Axis: Located in the carrier's symmetry plane, passing through the coordinate origin O p The normal of the vertical reference plane is positive when it points to the rear of the aircraft; p Axis: Located in the carrier's symmetry plane, perpendicular to the X p Axis, pointing to the back of the body is positive; Z p Axis: Determined by the right-hand rule, i.e. X p The axis passes through the palm of the right hand, with the thumb pointing to the Y p axis, then the four fingers point to Z p Axis; the rear end face of the vehicle is defined as the vertical reference plane.

7. A large non-cylindrical winged vehicle mass center measurement device, characterized in that: It includes a front car for supporting the front end of the product and a rear car for supporting the rear end of the product. Both the front car and the rear car include a measuring car and a supporting tooling carried on the measuring car. A weighing sensor is arranged in the measuring car, and the supporting tooling is carried on the weighing sensor. There are four weighing sensors, which are respectively set at the four corners of the measuring carriage; the front carriage and the rear carriage are both set on the guide rails, and can move closer or farther away from each other along the guide rails; the top of the supporting tooling is U-shaped to facilitate the positioning of the measured piece; there are also anti-bias lifting devices on the four corners of the measuring carriage to adjust the height of the supporting tooling; The measuring equipment also includes an anti-overturning support and protection platform, which is arranged in a fence-like manner around the outer periphery of the measuring vehicle, and four jacks are installed on its four columns; when the product is installed, the jacks are pressed against the bottom of the supporting tooling; when the product is measured, the top surface of the jacks descends and separates from the supporting tooling.

8. An electronic device, comprising a processor and a memory connected to the processor for storing instructions executable by the processor, characterized in that: The processor is used to execute the method for measuring the center of mass of a large non-cylindrical winged vehicle as described in any one of claims 1-6.

9. A server, characterized in that: It includes at least one processor and a memory communicatively connected to the processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor so that the at least one processor executes the method for measuring the center of mass of a large non-cylindrical winged vehicle as described in any one of claims 1-6.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for measuring the center of mass of a large non-cylindrical winged vehicle as described in any one of claims 1-6 is implemented.

Images