Mass center measuring system and method for winged aircraft

Abstract

The invention discloses a centroid measurement system and method for a winged aircraft, and belongs to the technical field of aircraft centroid measurement. The problems that an existing method is tedious in operation and low in efficiency and precision, and the measurement safety is prone to being affected are solved. Three-dimensional adjustable electric combined measurement is achieved through the front vehicle mechanism capable of adjusting the width distance and the lifting height and the ground steel rail enabling the horizontal distance between the front vehicle mechanism and the rear vehicle mechanism to be adjustable, and the electric combined measurement tool is adopted to replace a traditional fixed or manual tool replacement mode. Rapid and accurate adaptation of multi-model aircraft head supports is achieved, and the measurement method is easy and convenient to operate. The precision and repeatability of the two measurement postures are ensured, so that a reliable physical basis is provided for mass center calculation by adopting a flexible measurement method subsequently, and the problems of difficulty in multi-model compatibility, low measurement efficiency, poor safety and difficulty in ensuring the Z-direction mass center measurement precision of a fixed measurement table are effectively solved. The method can be applied to measurement of the mass center of the aircraft.

Description

Technical Field

[0001] This invention belongs to the field of aircraft center of mass measurement technology, specifically relating to a center of mass measurement system and method for winged aircraft. Background Technology

[0002] The center of mass (CMC) is a crucial parameter in the overall design, trajectory control, and attitude control of an aircraft. The accuracy of CMC measurement directly impacts attitude control, as it provides design input for the aircraft's attitude control system. Inaccurate CMC positioning leads to increased environmental disturbance torques and inaccurate measurements of the aircraft's inertial tensor. Both of these factors cause errors in control torque calculations, ultimately resulting in uncorrectable attitude deviations. Therefore, researching three-dimensional CMC measurement technology for aircraft is of great significance.

[0003] Large winged spacecraft have a non-rotating structure and can only be positioned in specific locations. When measuring the three-dimensional center of mass of such products, due to safety and positioning issues, the product cannot be tilted 90 degrees to measure the center of mass position parameters in the height direction. Therefore, a tilted center of mass testing method is often used to measure the center of mass position parameters in the height direction. However, most common three-dimensional center of mass measurement equipment uses a fixed measuring table, which cannot adapt to the measurement needs of spacecraft with different diameters and support widths, meaning poor tooling versatility. Furthermore, switching between measurement objects is cumbersome and inefficient. In center of mass measurement, it is often impossible to complete the entire three-dimensional center of mass measurement in a single setup. Using tilting instead of a 90° tilt to measure the center of mass position parameters in the height direction usually requires a second manual setup. During the tilting attitude adjustment, product movement is prone to occur, which can affect measurement safety and accuracy. Moreover, existing tilted center of mass testing methods are only suitable for measuring the center of mass of small spacecraft with dimensions within 3 meters. Summary of the Invention

[0004] The purpose of this invention is to address the problems of existing measurement methods being applicable only to aircraft of limited size, cumbersome operation, low efficiency and accuracy, and easily compromised measurement safety. Therefore, this invention proposes a support-adjustable center of mass measurement system and method for winged aircraft.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] According to one aspect of the present invention, a center of mass measurement system for a winged aircraft is provided, the system specifically comprising a front mechanism and a rear mechanism, wherein:

[0007] The front carriage mechanism includes a tooling base, a first column, a second column, a first lead screw and nut pair, a second lead screw and nut pair, a linear guide, a first electric push rod and a second electric push rod, a front measuring carriage, a first support block and a second support block;

[0008] The upper surface of the tooling base is provided with multiple linear guide rails. The first column and the second column are slidably mounted on the upper surface of the tooling base through the linear guide rails, and the first column and the second column are symmetrically arranged about the central axis of the tooling base.

[0009] A first electric push rod and a second electric push rod are provided between the first column and the second column. The telescopic rod of the first electric push rod is connected to the first column, and the telescopic rod of the second electric push rod is connected to the second column.

[0010] The first electric push rod and the second electric push rod are used to change the distance between the first column and the second column.

[0011] The second column and the second column are both provided with slide rails. The first support block is fixedly connected to the nut of the first lead screw nut pair and is slidably connected to the slide rail on the second column. The second support block is fixedly connected to the nut of the second lead screw nut pair and is slidably connected to the slide rail on the second column.

[0012] The first support block is provided with a first support frame, and the second support block is provided with a second support frame;

[0013] The nose of the aircraft is fixed between the first and second columns by the first support frame and the second support frame;

[0014] The front measuring carriage is located below the tooling base;

[0015] The rear vehicle mechanism includes a rear measuring vehicle and a third support frame;

[0016] The support frame is used to hold the tail of the aircraft, and the rear measuring vehicle is located below the third support frame.

[0017] Furthermore, weighing sensors are installed at the four bottom corners of the upper surface of both the front and rear measuring vehicles.

[0018] According to another aspect of the present invention, a method for measuring the center of mass of a winged aircraft is provided, the method specifically comprising the following steps:

[0019] Step 1: Record the measured values ​​of the four weighing sensors on the front measuring vehicle and the four weighing sensors on the rear measuring vehicle when unloaded.

[0020] The coordinates of the geometric center of the tooling base in the reference coordinate system, the coordinates of the three reference points on the front measuring vehicle and the three reference points on the rear measuring vehicle in the reference coordinate system are measured using a laser tracker when the tooling base is unloaded.

[0021] Then, based on the coordinate transformation relationship between the four load cells on the front measuring vehicle and the three reference points on the front measuring vehicle, the coordinates of the four load cells on the front measuring vehicle in the reference coordinate system are obtained; based on the coordinate transformation relationship between the four load cells on the rear measuring vehicle and the three reference points on the rear measuring vehicle, the coordinates of the four load cells on the rear measuring vehicle in the reference coordinate system are obtained.

[0022] Step 2: Based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, the coordinates of the geometric center of the tooling base in the reference coordinate system, and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, calculate the transformation matrix from the sensor coordinate system to the reference coordinate system of the front measuring vehicle.

[0023] Similarly, the transformation matrix from the sensor coordinate system of the rear measuring vehicle to the reference coordinate system is obtained;

[0024] Step 3: Based on the transformation matrix from the front measuring vehicle's sensor coordinate system to the reference coordinate system and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, obtain the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the front measuring vehicle's sensor coordinate system. Mark the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the front measuring vehicle's sensor coordinate system as follows: ;

[0025] Based on the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the sensor coordinate system of the front measuring vehicle and the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, calculate the transformation matrix from the reference coordinate system of the front measuring vehicle to the reference coordinate system.

[0026] Similarly, based on the transformation matrix from the sensor coordinate system of the rear measuring vehicle to the reference coordinate system and the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the reference coordinate system, the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the sensor coordinate system of the rear measuring vehicle can be obtained.

[0027] Based on the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the sensor coordinate system of the rear measuring vehicle and the coordinates of the three reference points on the rear measuring vehicle in the reference coordinate system, calculate the transformation matrix from the reference coordinate system of the rear measuring vehicle to the reference coordinate system.

[0028] Step 4: Based on the transformation matrix from the front measuring vehicle reference coordinate system to the datum coordinate system and the transformation matrix from the front measuring vehicle sensor coordinate system to the datum coordinate system, calculate the transformation matrix from the front measuring vehicle sensor coordinate system to the front measuring vehicle reference coordinate system.

[0029] Based on the transformation matrix from the rear measurement vehicle reference coordinate system to the datum coordinate system and the transformation matrix from the rear measurement vehicle sensor coordinate system to the datum coordinate system, calculate the transformation matrix from the rear measurement vehicle sensor coordinate system to the rear measurement vehicle reference coordinate system.

[0030] Step 5: Load the aircraft under test onto the front and rear measurement vehicles, and initialize the aircraft on the front and rear measurement vehicles to a horizontal state;

[0031] Step 6: Record the measured values ​​of the four weighing sensors on the front measuring vehicle and the four weighing sensors on the rear measuring vehicle in a horizontal state; and use a laser tracker to obtain the coordinates of the four positioning points on the tested aircraft in a horizontal state in the reference coordinate system, as well as the coordinates of the three reference points on the front measuring vehicle and the three reference points on the rear measuring vehicle in the reference coordinate system.

[0032] Based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system and the coordinates of the four positioning points on the aircraft under test in the reference coordinate system, calculate the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the front measuring vehicle reference coordinate system to the reference coordinate system in the horizontal state.

[0033] Based on the coordinates of the three reference points on the rear measurement vehicle in the reference coordinate system and the coordinates of the four positioning points on the tested aircraft in the reference coordinate system, calculate the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the rear measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state.

[0034] Step 7: Based on the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the front measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state, obtain the transformation matrix from the aircraft coordinate system to the front measurement vehicle reference coordinate system.

[0035] Based on the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the rear measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state, the transformation matrix from the aircraft coordinate system to the rear measurement vehicle reference coordinate system is obtained.

[0036] Step 8: Based on the transformation matrix from the front measurement vehicle sensor coordinate system to the front measurement vehicle reference coordinate system and the transformation matrix from the aircraft coordinate system to the front measurement vehicle reference coordinate system, obtain the transformation matrix between the aircraft coordinate system and the front measurement vehicle sensor coordinate system under horizontal attitude.

[0037] Based on the transformation matrix from the rear measurement vehicle sensor coordinate system to the rear measurement vehicle reference coordinate system and the transformation matrix from the aircraft coordinate system to the rear measurement vehicle reference coordinate system, the transformation matrix between the aircraft coordinate system and the rear measurement vehicle sensor coordinate system under horizontal attitude is obtained.

[0038] Step 9: Subtract the measured values ​​of the weighing sensors at the corresponding positions in Step 6 and Step 1 to obtain the difference value corresponding to the weighing sensor at each position.

[0039] Establish a set of static moment equilibrium equations in the coordinate systems of the front and rear measuring vehicles respectively, and calculate the coordinates of the projection points of the resultant force points of the front and rear measuring vehicles in the horizontal state.

[0040] Step 10: Based on the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the front measuring vehicle, transform the coordinates of the projection point of the resultant force point of the front measuring vehicle to the aircraft coordinate system. Based on the transformation result, establish the equation of the first line of action of gravity of the front measuring vehicle in the aircraft coordinate system.

[0041] Similarly, based on the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the rear measuring vehicle, the coordinates of the projection point of the resultant force point of the rear measuring vehicle are transformed to the aircraft coordinate system, and the equation of the first line of action of gravity of the rear measuring vehicle is established.

[0042] Step 11: Increase the height of the aircraft's front end to tilt the aircraft. While the aircraft is tilted, repeat steps 6 to 10 to obtain the second gravity line equation for the front measuring vehicle and the second gravity line equation for the rear measuring vehicle.

[0043] Step 12: Determine the coordinates of the resultant force point of the front measuring vehicle based on the equations of the first and second lines of action of gravity. ;

[0044] The coordinates of the resultant force point of the rear measuring vehicle are determined based on the equations of the first and second lines of action of gravity of the rear measuring vehicle. ;

[0045] Step 13: Combine the coordinates of the resultant force point of the front measuring vehicle and the resultant force point of the rear measuring vehicle to obtain the three-dimensional centroid coordinates of the tested aircraft.

[0046] Furthermore, based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, the coordinates of the geometric center of the tooling base in the reference coordinate system, and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, the transformation matrix from the sensor coordinate system to the reference coordinate system is calculated; specifically:

[0047] The coordinates of the geometric center of the tooling base in the reference coordinate system are: The first measurement vehicle The coordinates of the bearing point of each weighing sensor in the reference coordinate system are as follows: The coordinates of the three reference points on the front measuring vehicle in the reference coordinate system are marked as follows: ;

[0048] Plane fitting is performed on the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle to obtain the plane. With the geometric center of the tooling base as the origin of the sensor coordinate system of the front measuring vehicle, the first reference point on the front measuring vehicle is... Projected onto a plane , obtain the projection point Connect the projection points and points , obtained from the projection point Point of view The vector, for the plane For each normal direction, draw a line connecting the normal direction to the projection point. Point of view The dot product of the vectors is used, and the normal direction corresponding to the dot product with a value of 1 is taken as the Z-axis direction of the front measuring vehicle sensor coordinate system. In the reference coordinate system, the unit vector of the Z-axis of the front measuring vehicle sensor coordinate system is... ;

[0049] The vector pointing from the geometric center of the fixture base to the weighing point of the first sensor on the front measuring vehicle is defined. This vector is then normalized; the resulting unit vector is the X-axis unit vector of the front measuring vehicle's sensor coordinate system. Denoteed in the reference coordinate system, the X-axis unit vector of the front measuring vehicle's sensor coordinate system is... ;

[0050] Draw the unit vector along the Z-axis and the X-axis unit vector The vector product of these vectors yields the unit Y-axis vector of the front measuring vehicle's sensor coordinate system in the reference coordinate system. ;

[0051] The transformation matrix from the sensor coordinate system of the front measuring vehicle to the reference coordinate system. for:

[0052]

[0053] in, This represents the transformation matrix from the sensor coordinate system of the front measuring vehicle to the reference coordinate system.

[0054] Furthermore, a set of static moment equilibrium equations is established in the coordinate system of the front measuring vehicle sensor to calculate the coordinates of the projection point of the resultant force point of the front measuring vehicle in a horizontal state; specifically:

[0055] The static moment equilibrium equations are as follows:

[0056]

[0057] in, This indicates that the bearing point of the first weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the bearing point of the first weighing sensor on the front measuring vehicle is located in the sensor coordinate system Y of the front measuring vehicle. S Coordinates along the axis; This indicates that the bearing point of the second weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the bearing point of the second weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates that the load-bearing point of the third weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the bearing point of the third weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates that the bearing point of the fourth weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the load-bearing point of the fourth weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis;

[0058] This indicates the difference corresponding to the first weighing sensor on the front measuring vehicle. This indicates the difference between the second weighing sensor on the front measuring vehicle. This indicates the difference corresponding to the third weighing sensor on the front measuring vehicle. This indicates the difference value corresponding to the fourth weighing sensor on the front measuring vehicle;

[0059] The first line of action of gravity of the front measuring vehicle passes through the point in the coordinate system of the front measuring vehicle's sensor. Since the direction of the line of action of gravity is vertically downward, the first line of action of gravity of the front measuring vehicle must pass through the point in the coordinate system of the front measuring vehicle's sensor. .

[0060] Furthermore, the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the front measuring vehicle is used to transform the coordinates of the projection point of the resultant force point of the front measuring vehicle to the aircraft coordinate system; specifically:

[0061]

[0062]

[0063] in, Point The corresponding coordinates in the spacecraft coordinate system point The corresponding coordinates in the spacecraft coordinate system.

[0064] Furthermore, in step ten, the equation of the first line of action of gravity of the forward measuring vehicle is established in the aircraft coordinate system based on the transformation result, specifically as follows:

[0065] According to the point and points At the corresponding point in the spacecraft coordinate system, establish the equation of the first line of action of gravity for the forward measuring vehicle in the spacecraft coordinate system:

[0066]

[0067] in, , and Indicates the directions of the three coordinate axes of the aircraft's coordinate system;

[0068] The equation of the second line of action of gravity of the front measuring vehicle is:

[0069]

[0070] in, and This indicates the coordinates of the two points along the second line of gravity of the forward measuring vehicle in the spacecraft coordinate system.

[0071] Furthermore, the specific process of step twelve is as follows:

[0072] Determine whether the equations of the first and second lines of action of gravity on the front measuring vehicle intersect;

[0073] If the equations of the first and second lines of action of gravity on the front measuring vehicle intersect, then the coordinates of the intersection point are the coordinates of the resultant force point of the front measuring vehicle. Simultaneously satisfying the linear equations of the two lines of action of gravity on the front measuring vehicle:

[0074]

[0075] If the equations of the first and second lines of action of gravity on the front measuring vehicle do not intersect, meaning the two lines of action of gravity on the front measuring vehicle are skew in space, then the midpoint of the common perpendicular of the first and second lines of action of gravity on the front measuring vehicle is taken as the point of resultant force on the front measuring vehicle. .

[0076] Furthermore, the specific process of step thirteen is as follows:

[0077]

[0078] in, Indicates the coordinates of the center of mass of the tested aircraft. This represents the average load measured twice by the four sensors of the front measuring vehicle in both horizontal and tilted states. This represents the average load of the four sensors on the rear measuring vehicle in two measurements, one in a horizontal state and the other in an inclined state.

[0079] in, , ;

[0080] , , , and This represents the measurement values ​​from four sensors on the front measurement vehicle when the aircraft is in a horizontal position. , , , and This indicates the readings from four sensors on the front measurement vehicle when the aircraft is tilted. Represents gravitational acceleration;

[0081] , , , and This indicates the measurement values ​​from four sensors on the vehicle when the aircraft is in a horizontal position. , , , and This indicates the measurement values ​​of the four sensors on the vehicle when the aircraft is tilted.

[0082] The beneficial effects of this invention are:

[0083] This invention achieves three-dimensional adjustable electrically powered combined measurement through an adjustable front mechanism with adjustable width and lifting height, and a ground rail that allows for adjustable horizontal distance between the front and rear mechanisms. It replaces traditional fixed or manually changeable tooling with a three-dimensional adjustable electrically powered combined measurement fixture, enabling rapid and accurate adaptation to the nose support of multiple aircraft models and sizes, while also simplifying the measurement method. The structural design of this invention ensures the accuracy and repeatability of two measurement attitudes, thus providing a reliable physical basis for subsequent centroid calculation using flexible measurement methods. It effectively solves the problems of difficult multi-model compatibility, low measurement efficiency, poor safety, and difficulty in guaranteeing Z-axis centroid measurement accuracy associated with fixed measurement stands. The measurement method of this invention can effectively reduce human intervention and automatically adjust the connection between the measurement system and the aircraft under test, greatly improving the measurement range and capability of the centroid measurement system. Attached Figure Description

[0084] Figure 1 This is a side view of the front vehicle mechanism of the present invention. Figure 1 ;

[0085] Figure 2 This is a side view of the front vehicle mechanism of the present invention. Figure 2 ;

[0086] Figure 3 This is a schematic diagram of the column assembly;

[0087] Figure 4 This is a schematic diagram of the front end of the aircraft when it is operating in a horizontal position;

[0088] Figure 5 This is a schematic diagram of the front end of the aircraft when it is operating in an inclined state;

[0089] Figure 6 This is an overall schematic diagram of the aircraft operating in a horizontal position;

[0090] Figure 7 This is a schematic diagram of the front and rear measuring vehicles;

[0091] Figure 8 This is a schematic diagram for measuring the car base;

[0092] Figure 9 This is a schematic diagram of the second support block;

[0093] Figure 10 It is a diagram showing the transformation relationships between different coordinate systems;

[0094] In the diagram, 1 represents the tooling base, 2 represents the first column, 3 represents the second column, 4 represents the first lead screw and nut pair, 5 represents the second lead screw and nut pair, 6 represents the linear guide rail, 7 represents the first electric push rod, 8 represents the front measuring carriage, 9 represents the rear measuring carriage, 10 represents the third support frame, 11 represents the first support block, 12 represents the second support block, 13 represents the first support frame, 14 represents the second support frame, 15 represents the weighing sensor, 16 represents the second electric push rod, and 17 represents the retractable anti-fall pin. Detailed Implementation

[0095] This invention utilizes a combined measuring mechanism including a front mechanism and a rear mechanism to achieve center of mass measurement. Through a highly compatible electric tooling, it achieves electric adjustment of the support span and electric control of the aircraft's tilt angle. Combined with the four-point weighing method and the flexible measurement principle, that is, by using a high-precision spatial coordinate measuring instrument (in this invention, a laser tracker is used, and the position of the laser tracker remains unchanged throughout the process), it accurately obtains the geometric center of the tooling base 1, the bearing points of the four weighing sensors on the front vehicle, the bearing points of the four weighing sensors on the rear vehicle, and the three-dimensional spatial positional relationship between the aircraft under test. Combining the four-point weighing method and the lifting and tilting measurement method, the measurement state of the aircraft in two attitudes, horizontal and tilted, is achieved through the lifting and lowering function of the support block on the front mechanism. Combined with the laser tracker, multi-coordinate system transformation is completed to accurately calculate the aircraft's mass and three-dimensional center of mass coordinates.

[0096] Specific Implementation Method 1: Combination Figure 1 This embodiment describes a center of mass measurement system for a winged aircraft. The system specifically includes a front mechanism and a rear mechanism, wherein:

[0097] The front carriage mechanism includes a tooling base 1, a first column 2, a second column 3, a first lead screw and nut pair 4, a second lead screw and nut pair 5, a linear guide rail 6, a first electric push rod 7, a second electric push rod 16, a front measuring carriage 8, a first support block 11, and a second support block 12.

[0098] The upper surface of the tooling base 1 is provided with multiple linear guide rails 6. The first column 2 and the second column 3 are slidably mounted on the upper surface of the tooling base 1 through the linear guide rails 6, and the first column 2 and the second column 3 are symmetrically arranged about the central axis of the tooling base 1.

[0099] A first electric push rod 7 and a second electric push rod 16 are provided between the first column 2 and the second column 3. The telescopic rod of the first electric push rod 7 is connected to the first column 2, and the telescopic rod of the second electric push rod 16 is connected to the second column 3.

[0100] The first electric push rod 7 and the second electric push rod 16 are used to change the distance between the first column 2 and the second column 3, so that the two columns move synchronously towards or in opposite directions, so that the system of the present invention can be applied to the measurement of aircraft with different diameters.

[0101] The second column 2 and the second column 3 are both provided with slide rails. The first support block 11 is fixedly connected to the nut of the first lead screw nut pair 4 and is slidably connected to the slide rail on the second column 2. The second support block 12 is fixedly connected to the nut of the second lead screw nut pair 5 and is slidably connected to the slide rail on the second column 3. By synchronously adjusting the height of the first support block 11 and the second support block 12, the attitude of the aircraft can be changed, so that the aircraft can be in a horizontal state or in an inclined state.

[0102] The first support block 11 is provided with a first support frame 13, and the second support block 12 is provided with a second support frame 14;

[0103] The nose of the aircraft is fixed between the first column 2 and the second column 3 by the first support frame 13 and the second support frame 14;

[0104] The front measuring vehicle 8 is located below the tooling base 1;

[0105] The rear vehicle mechanism includes a rear measuring vehicle 9 and a third support frame 10;

[0106] The support frame 10 is used to hold the tail of the aircraft, and the rear measuring vehicle 9 is located below the third support frame 10.

[0107] Specific Implementation Method Two: This implementation method is a further limitation of Specific Implementation Method One. Weighing sensors 15 are provided at the four bottom corners of the upper surface of the front measuring vehicle 8 and the rear measuring vehicle 9.

[0108] The weighing sensor 15 in this embodiment is used to measure the mass of the aircraft.

[0109] The working principle of the centroid measurement system of the present invention is as follows:

[0110] The entire measurement process of this invention requires the aircraft to be in both a horizontal and a tilted state. First, in the horizontal state, the aircraft's head is fixed by a first support block 11 and symmetrically arranged second support blocks 12, suspending the head of the aircraft on a first support frame 13 and a second support frame 14. At this point, it is not necessary to use a first screw-nut pair 4 and a second screw-nut pair 5 to raise the height of the first support block 11 and the symmetrically arranged second support block 12. In the horizontal state, the mass measurement value of the weighing sensor and the coordinate measurement value of the laser tracker are obtained. A drive motor drives the screw to rotate, and the nut moves up and down along the axis of the screw under the limit of the support block, thereby raising and lowering the support block. The first and second support blocks are controlled to slide upwards along the slide rail by the first and second screw-nut pairs, raising the height of the first support block 11 and the symmetrically arranged second support block 12, thus raising the aircraft's head until it is higher than the tail, achieving a tilted state. The entire operation is electrically controlled. In the tilted state, the mass measurement value of the weighing sensor and the coordinate measurement value of the laser tracker are obtained. Furthermore, both the first support block 11 and the second support block housing 12 of this invention are equipped with retractable anti-fall pins, such as... Figure 9 As shown, the second support block 12 is equipped with a retractable anti-fall pin 17. When the aircraft is tilted, the anti-fall pin 17 can stably fix the second support block 12 to the third column 3 to prevent it from falling off.

[0111] Furthermore, it should be noted that the front measuring vehicle 8 and the rear measuring vehicle 9 can slide on ground rails. This allows for easy adjustment of the distance between the two vehicles when the aircraft's status changes. Additionally, adjusting the horizontal distance between the two vehicles allows for the inspection of aircraft of different lengths, enhancing the versatility of the measurement system. The ground rails also define the movement direction of the front and rear measuring vehicles, ensuring that their measurement reference points are always maintained. This facilitates personnel adjustments while guaranteeing measurement accuracy.

[0112] Since the load-bearing points of the weighing sensors are obscured by the tooling and the aircraft after being loaded, they cannot be directly measured by the laser tracker. Therefore, it is necessary to introduce a reference coordinate system established by three visible reference points. By using the fixed transformation relationship between the sensor system and the reference system calibrated when unloaded, the spatial orientation of the sensor system after being loaded can be indirectly obtained.

[0113] Specific Implementation Method Three: Combination Figure 10 This embodiment describes a method for measuring the center of mass of a winged aircraft. Before introducing the measurement method of this invention, the following coordinate system is first defined:

[0114] Spacecraft coordinate system O P -XP Y P Z P The aircraft coordinate system is related to the aircraft under test and is usually established on a certain end face of the aircraft under test. The results of the centroid measurement ultimately need to be described in the aircraft coordinate system.

[0115] Sensor coordinate system O S -X S Y S Z S The sensor coordinate system is determined based on the load-bearing points of the weighing sensors on the measuring platform. The front and rear vehicles each correspond to a separate sensor coordinate system. The sensor coordinate system of the front vehicle is denoted as O. S1 -X S1 Y S1 Z S1 Let the coordinate system of the rear vehicle sensor be denoted as O. S2 -X S2 Y S2 Z S2 ;

[0116] Reference coordinate system O R -X R Y R Z R During measurement, the coordinates of the load-bearing points of the weighing sensor cannot be directly measured due to the obstruction of the upper auxiliary tooling and the aircraft under test. Therefore, the transformation relationship between the sensor coordinate system and the aircraft coordinate system cannot be directly calculated. Introducing a reference coordinate system can indirectly calculate the transformation relationship.

[0117] Reference coordinate system O B -X B Y B Z B To determine the relative positional relationship between the tested aircraft and the sensor's load-bearing points, it is necessary to use a laser tracker to measure the coordinates of the aircraft's four positioning points and determine the transformation relationship between the various coordinate systems.

[0118] The coordinates of each sensor, reference point, and positioning point were initially described in the reference coordinate system provided by the laser tracker.

[0119] The method specifically includes the following steps:

[0120] Step 1: Record the measured values ​​of the four weighing sensors on the front measuring vehicle and the four weighing sensors on the rear measuring vehicle when unloaded.

[0121] The coordinates of the geometric center of the tooling base 1 under no-load conditions, the coordinates of the three reference points on the front measuring vehicle (i.e., the three target seats set on the front measuring vehicle before the start of measurement), and the coordinates of the three reference points on the rear measuring vehicle (i.e., the three target seats set on the rear measuring vehicle before the start of measurement) under the reference coordinate system are measured using a laser tracker.

[0122] Then, based on the coordinate transformation relationship between the four load cells on the front measuring vehicle and the three reference points on the front measuring vehicle, the coordinates of the four load cells on the front measuring vehicle in the reference coordinate system are obtained; based on the coordinate transformation relationship between the four load cells on the rear measuring vehicle and the three reference points on the rear measuring vehicle, the coordinates of the four load cells on the rear measuring vehicle in the reference coordinate system are obtained.

[0123] The coordinate transformation relationship between the load-bearing point of the weighing sensor on the front measuring vehicle and the coordinate transformation relationship between the load-bearing point of the weighing sensor on the rear ...

[0124] It should be noted that the reference coordinate system is a three-dimensional rectangular coordinate system. In this invention, three laser trackers are used to measure the coordinates. Each laser tracker is used to measure the coordinates of one coordinate axis of the reference coordinate system. The intersection of the three measured coordinate axes is the origin of the reference coordinate system.

[0125] Step 2: Based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, the coordinates of the geometric center of the tooling base 1 in the reference coordinate system, and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, calculate the transformation matrix from the sensor coordinate system to the reference coordinate system of the front measuring vehicle.

[0126] Taking the previous measuring vehicle as an example, specifically:

[0127] The coordinates of the geometric center of the tooling base 1 in the reference coordinate system are: The first measurement vehicle The coordinates of the bearing point of each weighing sensor in the reference coordinate system are as follows: The coordinates of the three reference points on the front measuring vehicle in the reference coordinate system are marked as follows: ;

[0128] Plane fitting is performed on the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle to obtain the plane. Project the geometric center of the tooling base 1 onto the plane. The projection coordinates are as follows ;

[0129] Taking the geometric center of the tooling base 1 as the origin of the front measuring vehicle sensor coordinate system, it should be noted that: the plane The unit normal vector has two possible directions. To ensure the plane... The unit normal vector is the Z-axis unit vector of the front measuring vehicle sensor coordinate system that we need. We also need to determine the direction of the Z-axis unit vector:

[0130] The first reference point on the front measuring vehicle Projected onto a plane , obtain the projection point Connect the projection points and points , obtained from the projection point Point of view The vector, for the plane For each normal direction, draw a line connecting the normal direction to the projection point. Point of view The dot product of the vectors is used, and the normal direction corresponding to the dot product with a value of 1 is taken as the Z-axis direction of the front measuring vehicle sensor coordinate system. In the reference coordinate system, the unit vector of the Z-axis of the front measuring vehicle sensor coordinate system is... ;

[0131] Construct a vector pointing from the geometric center of fixture base 1 to the weighing point of the first sensor on the front measuring vehicle. Normalize this vector; the resulting unit vector is the X-axis unit vector of the sensor coordinate system of the front measuring vehicle. In the reference coordinate system, the X-axis unit vector of the sensor coordinate system of the front measuring vehicle is: ;

[0132] Draw the unit vector along the Z-axis and the X-axis unit vector The vector product of these vectors yields the unit Y-axis vector of the front measuring vehicle's sensor coordinate system in the reference coordinate system. ;

[0133] Thus, the transformation matrix from the sensor coordinate system of the front measuring vehicle to the reference coordinate system can be obtained. for:

[0134]

[0135] Assume any point in space is in the current reference coordinate system O B -X B Y B Z B The coordinates below are ( This point is in the sensor coordinate system O of the front measuring vehicle. S -X S Y S ZS The coordinates below are ( The relationship between the two sets of coordinates is shown in the following equation:

[0136] or

[0137] Similarly, the transformation matrix from the sensor coordinate system of the rear measuring vehicle to the reference coordinate system is obtained;

[0138] Step 3: Based on the transformation matrix from the front measuring vehicle's sensor coordinate system to the reference coordinate system and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, obtain the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the front measuring vehicle's sensor coordinate system. Mark the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the front measuring vehicle's sensor coordinate system as follows: ;

[0139] Based on the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the sensor coordinate system of the front measuring vehicle and the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, calculate the transformation matrix from the reference coordinate system of the front measuring vehicle to the reference coordinate system.

[0140] Taking the previous measuring vehicle as an example, specifically:

[0141] by The origin of the front measuring vehicle's reference coordinate system, i.e., the coordinates of the origin of the front measuring vehicle's reference coordinate system in the reference coordinate system, are: ;

[0142] The plane is obtained by performing plane fitting on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system. ,flat The unit normal vector has two possible directions. To ensure the plane... The unit normal vector is the Z-axis unit vector of the reference coordinate system of the front measuring vehicle that we need. We also need to consider the plane. Determine the direction using the unit normal vector:

[0143] Point Projected onto a plane Obtain the projection point Connection point and points , obtained from point Point of view The vector, for the plane For each normal direction, draw a line connecting the normal direction to the point... Point of view The dot product of the vectors is taken as the normal direction corresponding to the dot product with a value of 1, and denoted as the Z-axis direction of the front measuring vehicle reference coordinate system in the reference coordinate system. The Z-axis unit vector of the front measuring vehicle reference coordinate system is denoted as . ;

[0144] Connection point and points , obtained from the origin Pointing to the second reference point on the forward measuring vehicle The vector, and will be from the origin Pointing to the second reference point on the forward measuring vehicle Normalize the vector to obtain the unit vector, which is the Y-axis unit vector of the front measuring vehicle reference coordinate system. Let the Y-axis unit vector of the front measuring vehicle reference coordinate system in the reference coordinate system be denoted as... ;

[0145] Construct a unit vector and The vector product of these vectors yields the unit X-axis vector of the front measuring vehicle's reference coordinate system in the base coordinate system. ;

[0146] The transformation matrix from the reference coordinate system of the forward measuring vehicle to the datum coordinate system. for:

[0147]

[0148] Assume any point in space is in the current reference coordinate system O B -X B Y B Z B The coordinates below are ( This point is in reference coordinate system O. R -X R Y R Z R The coordinates are ( The relationship between the two sets of coordinates is shown in the following equation:

[0149] or

[0150] Similarly, based on the transformation matrix from the sensor coordinate system of the rear measuring vehicle to the reference coordinate system and the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the reference coordinate system, the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the sensor coordinate system of the rear measuring vehicle can be obtained.

[0151] Based on the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the sensor coordinate system of the rear measuring vehicle and the coordinates of the three reference points on the rear measuring vehicle in the reference coordinate system, calculate the transformation matrix from the reference coordinate system of the rear measuring vehicle to the reference coordinate system.

[0152] Step 4: Based on the transformation matrix from the front measuring vehicle reference coordinate system to the datum coordinate system and the transformation matrix from the front measuring vehicle sensor coordinate system to the datum coordinate system, calculate the transformation matrix from the front measuring vehicle sensor coordinate system to the front measuring vehicle reference coordinate system.

[0153] Based on the transformation matrix from the rear measurement vehicle reference coordinate system to the datum coordinate system and the transformation matrix from the rear measurement vehicle sensor coordinate system to the datum coordinate system, calculate the transformation matrix from the rear measurement vehicle sensor coordinate system to the rear measurement vehicle reference coordinate system.

[0154] Specifically: Taking the previous measuring vehicle as an example, the sensor coordinate system O of the previous measuring vehicle... S -X S Y S Z S To the reference coordinate system O of the front measuring vehicle R -X R Y R Z R Transformation matrix for:

[0155]

[0156] Assuming any point in space lies in the current sensor coordinate system O S -X S Y S Z S The coordinates below are ( This point is in reference coordinate system O. R -X R Y R Z R The coordinates below are ( The relationship between the two sets of coordinates is shown in the following equation:

[0157]

[0158] Step 5: Load the aircraft under test onto the front and rear measurement vehicles, and initialize the aircraft on the front and rear measurement vehicles to a horizontal state;

[0159] Step 6: Record the measured values ​​of the four weighing sensors on the front measuring vehicle and the four weighing sensors on the rear measuring vehicle in a horizontal state; and use a laser tracker to obtain the coordinates of the four positioning points on the tested aircraft in a horizontal state in the reference coordinate system, as well as the coordinates of the three reference points on the front measuring vehicle and the three reference points on the rear measuring vehicle in the reference coordinate system.

[0160] It should be noted that the four positioning points are the two contact points between the two support blocks of the front measuring vehicle and the two contact points between the aircraft and the support blocks of the rear measuring vehicle. The first positioning point is defined as the point on the +Y axis of the aircraft coordinate system.

[0161] Based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system and the coordinates of the four positioning points on the aircraft under test in the reference coordinate system, calculate the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the front measuring vehicle reference coordinate system to the reference coordinate system in the horizontal state.

[0162] Based on the coordinates of the three reference points on the rear measurement vehicle in the reference coordinate system and the coordinates of the four positioning points on the tested aircraft in the reference coordinate system, calculate the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the rear measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state.

[0163] Taking the previous measuring vehicle as an example, specifically:

[0164] The coordinates of the four positioning points on the tested aircraft in the reference coordinate system are as follows: The coordinates of the three reference points on the front measuring vehicle in the reference coordinate system are as follows: ;

[0165] The coordinates of the four positioning points on the tested aircraft in the reference coordinate system are fitted to obtain the aircraft reference plane. The four positioning points on the tested aircraft are projected onto a plane. , mark the projection coordinates as ;

[0166] Point Projected onto a plane Obtain the projection point , obtained from point Point of view The vector, for the plane For each normal vector direction, the normal vector is perpendicular to the point... Point of view Take the dot product of the vectors, and denote the normal direction corresponding to the dot product with a value of 1 as the X-axis direction of the flight coordinate system. In the reference coordinate system, the unit X-axis vector of the aircraft coordinate system is... ;

[0167] In plane Top of 4 projection points Perform planar circle fitting, and use the center of the fitted circle as the origin of the spacecraft coordinate system. And the coordinates of the center of the fitted circle in the current reference coordinate system are denoted as ;

[0168] Connect the center of the fitted circle to the projection point corresponding to the first positioning point on the tested aircraft. This yields a vector pointing from the center of the fitted circle to the projection point corresponding to the first positioning point. Normalizing this vector, we obtain the unit vector of the Y-axis of the aircraft coordinate system. Let the unit vector of the Y-axis of the aircraft coordinate system in the reference coordinate system be denoted as... ;

[0169] Construct a unit vector and The vector product of these vectors yields the unit vector of the Z-axis of the aircraft coordinate system in the reference coordinate system. ;

[0170] Thus, the transformation matrix from the aircraft coordinate system to the reference coordinate system can be obtained. :

[0171]

[0172] A plane is obtained by performing plane fitting on the coordinates of the three reference points. , will point Projected onto a plane Obtain the projection point Then obtain the point Point of view Vectors; for a plane For each normal vector, calculate the normal vector and the vector from the point. Point of view The dot product of the vectors is taken as the direction of the normal vector corresponding to the dot product with a value of 1, and the Z-axis direction of the front measuring vehicle reference coordinate system is denoted as . ;

[0173] Will As the origin of the reference coordinate system of the front measuring vehicle, the coordinates from the origin... Pointing to the second reference point Normalize the vector to obtain the unit vector, which is the Y-axis unit vector of the front measuring vehicle reference coordinate system. Let the Y-axis unit vector of the front measuring vehicle reference coordinate system in the reference coordinate system be denoted as... ;

[0174] Construct a unit vector and The vector product of these vectors yields the unit vector of the X-axis in the reference coordinate system of the front measuring vehicle, within the base coordinate system. ;

[0175] Thus, the transformation matrix from the previous measuring vehicle's reference coordinate system to the current reference coordinate system can be obtained. :

[0176]

[0177] according to and Obtain the transformation matrix from the aircraft coordinate system to the reference coordinate system of the front measurement vehicle.

[0178] Step 7: Based on the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the front measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state, obtain the transformation matrix from the aircraft coordinate system to the front measurement vehicle reference coordinate system.

[0179] Based on the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the rear measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state, the transformation matrix from the aircraft coordinate system to the rear measurement vehicle reference coordinate system is obtained.

[0180] Step 8: Based on the transformation matrix from the front measurement vehicle sensor coordinate system to the front measurement vehicle reference coordinate system and the transformation matrix from the aircraft coordinate system to the front measurement vehicle reference coordinate system, obtain the transformation matrix between the aircraft coordinate system and the front measurement vehicle sensor coordinate system under horizontal attitude.

[0181] Based on the transformation matrix from the rear measurement vehicle sensor coordinate system to the rear measurement vehicle reference coordinate system and the transformation matrix from the aircraft coordinate system to the rear measurement vehicle reference coordinate system, the transformation matrix between the aircraft coordinate system and the rear measurement vehicle sensor coordinate system under horizontal attitude is obtained.

[0182] Step 9: Subtract the measured values ​​of the weighing sensors at the corresponding positions in Step 6 and Step 1, that is, take the difference between the measured values ​​of the weighing sensors at the same position to obtain the difference value corresponding to the weighing sensor at each position.

[0183] Establish a set of static moment equilibrium equations in the coordinate systems of the front and rear measuring vehicles respectively, and calculate the coordinates of the projection points of the resultant force points of the front and rear measuring vehicles in the horizontal state.

[0184] Taking the previous measuring vehicle as an example, the static moment equilibrium equations are as follows:

[0185]

[0186] in, This indicates that the bearing point of the first weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the bearing point of the first weighing sensor on the front measuring vehicle is located in the sensor coordinate system Y of the front measuring vehicle. S Coordinates along the axis; This indicates that the bearing point of the second weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the bearing point of the second weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates that the load-bearing point of the third weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the bearing point of the third weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates that the bearing point of the fourth weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis, This indicates that the load-bearing point of the fourth weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis;

[0187] This indicates the difference corresponding to the first weighing sensor on the front measuring vehicle. This indicates the difference between the second weighing sensor on the front measuring vehicle. This indicates the difference corresponding to the third weighing sensor on the front measuring vehicle. This indicates the difference value corresponding to the fourth weighing sensor on the front measuring vehicle;

[0188] The first line of action of gravity of the front measuring vehicle passes through the point in the coordinate system of the front measuring vehicle's sensor. Since the direction of the line of action of gravity is vertically downward, the first line of action of gravity of the front measuring vehicle must pass through the point in the coordinate system of the front measuring vehicle's sensor. ;

[0189] Similarly, the coordinates of the projection point of the resultant force point of the rear measuring vehicle are obtained;

[0190] Step 10: Based on the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the front measuring vehicle, project the coordinates of the resultant force point of the front measuring vehicle (i.e., the point...). and points Transform to the aircraft coordinate system;

[0191] Specifically,

[0192]

[0193]

[0194] in, Point The corresponding coordinates in the spacecraft coordinate system point The corresponding coordinates in the spacecraft coordinate system;

[0195] According to the point and points The corresponding point in the spacecraft coordinate system, in spacecraft coordinate system O P -X P Y P Z P The equation for the first line of action of gravity of the measuring vehicle is established in the middle:

[0196]

[0197] Similarly, based on the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the rear measuring vehicle, the coordinates of the projection point of the resultant force point of the rear measuring vehicle are transformed to the aircraft coordinate system, and the equation of the first line of action of gravity of the rear measuring vehicle is established.

[0198] Step 11: Increase the height of the aircraft's front end to tilt the aircraft. While the aircraft is tilted, repeat steps 6 to 10 to obtain the second gravity line equation for the front measuring vehicle and the second gravity line equation for the rear measuring vehicle.

[0199] Taking the previous measuring vehicle as an example, the equation of the second line of action of gravity for the previous measuring vehicle is:

[0200]

[0201] in, and This indicates the coordinates of the two points passed through by the second line of gravity action of the front measuring vehicle in the spacecraft coordinate system;

[0202] Step 12: Determine the coordinates of the resultant force point of the front measuring vehicle based on the equations of the first and second lines of action of gravity. ;

[0203] Considering the possibility of errors in actual measurements, the two lines of action of gravity may not intersect perfectly. In this case, taking the midpoint of the common perpendicular of the two skew lines as the best estimate of the coordinates of the resultant force point can effectively suppress the influence of measurement errors.

[0204] Specifically, determine whether the equations of the first and second lines of action of gravity of the front measuring vehicle intersect;

[0205] If the equations of the first and second lines of action of gravity on the front measuring vehicle intersect, then the coordinates of the intersection point are the coordinates of the resultant force point of the front measuring vehicle. Simultaneously satisfying the linear equations of the two lines of action of gravity on the front measuring vehicle:

[0206] .

[0207] If the equations of the first and second lines of action of gravity on the front measuring vehicle do not intersect, meaning the two lines of action of gravity on the front measuring vehicle are skew in space, then the midpoint of the common perpendicular of the first and second lines of action of gravity on the front measuring vehicle is taken as the point of resultant force on the front measuring vehicle. ;

[0208] Similarly, the coordinates of the resultant force point of the rear measuring vehicle are determined based on the equations of the first and second lines of action of gravity of the rear measuring vehicle. ;

[0209] Step 13: Using the principle of static moment balance, synthesize the coordinates of the resultant force point of the front measuring vehicle and the resultant force point of the rear measuring vehicle to obtain the aircraft coordinate system O. P -X P Y P Z P The three-dimensional centroid coordinates of the tested aircraft are as follows:

[0210] Specifically:

[0211]

[0212] in, Indicates the coordinates of the center of mass of the tested aircraft. This represents the average load measured twice by the four sensors of the front measuring vehicle in both horizontal and tilted states. This represents the average load of the four sensors on the rear measuring vehicle in two measurements, one in a horizontal state and the other in an inclined state.

[0213] in, , ;

[0214] , , , and This represents the measurement values ​​from four sensors on the front measurement vehicle when the aircraft is in a horizontal position. , , , and This indicates the readings from four sensors on the front measurement vehicle when the aircraft is tilted. Represents gravitational acceleration;

[0215] , , , and This indicates the measurement values ​​from four sensors on the vehicle when the aircraft is in a horizontal position. , , , and This indicates the measurement values ​​of the four sensors on the vehicle when the aircraft is tilted.

[0216] At this point, the position of the center of mass in the spacecraft coordinate system has been determined.

[0217] The above examples of the present invention are merely illustrative of the computational model and process of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A centroid measurement system for winged aircraft, characterized in that, The system specifically includes a front vehicle mechanism and a rear vehicle mechanism, wherein: The front carriage mechanism includes a tooling base (1), a first column (2), a second column (3), a first lead screw and nut pair (4), a second lead screw and nut pair (5), a linear guide rail (6), a first electric push rod (7), a second electric push rod (16), a front measuring carriage (8), a first support block (11), and a second support block (12); The upper surface of the tooling base (1) is provided with multiple linear guide rails (6). The first column (2) and the second column (3) are slidably installed on the upper surface of the tooling base (1) through the linear guide rails (6), and the first column (2) and the second column (3) are symmetrically arranged about the central axis of the tooling base (1). A first electric push rod (7) and a second electric push rod (16) are provided between the first column (2) and the second column (3). The telescopic rod of the first electric push rod (7) is connected to the first column (2), and the telescopic rod of the second electric push rod (16) is connected to the second column (3). The first electric push rod (7) and the second electric push rod (16) are used to change the distance between the first column (2) and the second column (3); The second column (2) and the second column (3) are both provided with slide rails. The first support block (11) is fixedly connected to the nut of the first lead screw nut pair (4), and the first support block (11) is slidably connected to the slide rail on the second column (2). The second support block (12) is fixedly connected to the nut of the second lead screw nut pair (5), and the second support block (12) is slidably connected to the slide rail on the second column (3). The first support block (11) is provided with a first support frame (13), and the second support block (12) is provided with a second support frame (14). The nose of the aircraft is fixed between the first column (2) and the second column (3) by the first support frame (13) and the second support frame (14); The front measuring vehicle (8) is located below the tooling base (1); The rear vehicle mechanism includes a rear measuring vehicle (9) and a third support frame (10). The support frame (10) is used to hold the tail of the aircraft, and the rear measuring vehicle (9) is located below the third support frame (10).

2. The centroid measurement system for a winged aircraft according to claim 1, characterized in that, Weighing sensors (15) are installed at the four bottom corners of the upper surface of the front measuring vehicle (8) and the rear measuring vehicle (9).

3. A method for measuring the center of mass of a winged aircraft based on the center of mass measurement system of claim 1, characterized in that, The method specifically includes the following steps: Step 1: Record the measured values ​​of the four weighing sensors on the front measuring vehicle and the four weighing sensors on the rear measuring vehicle when unloaded. The coordinates of the geometric center of the tooling base (1) under no-load conditions, the coordinates of the three reference points on the front measuring vehicle and the three reference points on the rear measuring vehicle under the reference coordinate system were measured using a laser tracker. Then, based on the coordinate transformation relationship between the four load cells on the front measuring vehicle and the three reference points on the front measuring vehicle, the coordinates of the four load cells on the front measuring vehicle in the reference coordinate system are obtained; based on the coordinate transformation relationship between the four load cells on the rear measuring vehicle and the three reference points on the rear measuring vehicle, the coordinates of the four load cells on the rear measuring vehicle in the reference coordinate system are obtained. Step 2: Based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, the coordinates of the geometric center of the tooling base (1) in the reference coordinate system, and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, calculate the transformation matrix from the sensor coordinate system to the reference coordinate system of the front measuring vehicle. Similarly, the transformation matrix from the rear measuring vehicle sensor coordinate system to the reference coordinate system is obtained; Step 3: Based on the transformation matrix from the front measuring vehicle's sensor coordinate system to the reference coordinate system and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system, obtain the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the front measuring vehicle's sensor coordinate system. Mark the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the front measuring vehicle's sensor coordinate system as follows: ; Based on the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the sensor coordinate system of the front measuring vehicle and the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, calculate the transformation matrix from the reference coordinate system of the front measuring vehicle to the reference coordinate system. Similarly, based on the transformation matrix from the sensor coordinate system of the rear measuring vehicle to the reference coordinate system and the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the reference coordinate system, the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the sensor coordinate system of the rear measuring vehicle can be obtained. Based on the coordinates of the bearing points of the four weighing sensors on the rear measuring vehicle in the sensor coordinate system of the rear measuring vehicle and the coordinates of the three reference points on the rear measuring vehicle in the reference coordinate system, calculate the transformation matrix from the reference coordinate system of the rear measuring vehicle to the reference coordinate system. Step 4: Based on the transformation matrix from the front measuring vehicle reference coordinate system to the datum coordinate system and the transformation matrix from the front measuring vehicle sensor coordinate system to the datum coordinate system, calculate the transformation matrix from the front measuring vehicle sensor coordinate system to the front measuring vehicle reference coordinate system. Based on the transformation matrix from the rear measurement vehicle reference coordinate system to the datum coordinate system and the transformation matrix from the rear measurement vehicle sensor coordinate system to the datum coordinate system, calculate the transformation matrix from the rear measurement vehicle sensor coordinate system to the rear measurement vehicle reference coordinate system. Step 5: Load the aircraft under test onto the front and rear measurement vehicles, and initialize the aircraft on the front and rear measurement vehicles to a horizontal state; Step 6: Record the measured values ​​of the four weighing sensors on the front measuring vehicle and the four weighing sensors on the rear measuring vehicle in a horizontal state; and use a laser tracker to obtain the coordinates of the four positioning points on the tested aircraft in a horizontal state in the reference coordinate system, as well as the coordinates of the three reference points on the front measuring vehicle and the three reference points on the rear measuring vehicle in the reference coordinate system. Based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system and the coordinates of the four positioning points on the aircraft under test in the reference coordinate system, calculate the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the front measuring vehicle reference coordinate system to the reference coordinate system in the horizontal state. Based on the coordinates of the three reference points on the rear measurement vehicle in the reference coordinate system and the coordinates of the four positioning points on the tested aircraft in the reference coordinate system, calculate the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the rear measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state. Step 7: Based on the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the front measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state, obtain the transformation matrix from the aircraft coordinate system to the front measurement vehicle reference coordinate system. Based on the transformation matrix from the aircraft coordinate system to the reference coordinate system and the transformation matrix from the rear measurement vehicle reference coordinate system to the reference coordinate system in the horizontal state, the transformation matrix from the aircraft coordinate system to the rear measurement vehicle reference coordinate system is obtained. Step 8: Based on the transformation matrix from the front measurement vehicle sensor coordinate system to the front measurement vehicle reference coordinate system and the transformation matrix from the aircraft coordinate system to the front measurement vehicle reference coordinate system, obtain the transformation matrix between the aircraft coordinate system and the front measurement vehicle sensor coordinate system under horizontal attitude. Based on the transformation matrix from the rear measurement vehicle sensor coordinate system to the rear measurement vehicle reference coordinate system and the transformation matrix from the aircraft coordinate system to the rear measurement vehicle reference coordinate system, the transformation matrix between the aircraft coordinate system and the rear measurement vehicle sensor coordinate system under horizontal attitude is obtained. Step 9: Subtract the measured values ​​of the weighing sensors at the corresponding positions in Step 6 and Step 1 to obtain the difference value corresponding to the weighing sensor at each position. Establish a set of static moment equilibrium equations in the coordinate systems of the front and rear measuring vehicles respectively, and calculate the coordinates of the projection points of the resultant force points of the front and rear measuring vehicles in the horizontal state. Step 10: Based on the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the front measuring vehicle, transform the coordinates of the projection point of the resultant force point of the front measuring vehicle to the aircraft coordinate system. Based on the transformation result, establish the equation of the first line of action of gravity of the front measuring vehicle in the aircraft coordinate system. Similarly, based on the transformation matrix between the aircraft coordinate system and the sensor coordinate system of the rear measuring vehicle, the coordinates of the projection point of the resultant force point of the rear measuring vehicle are transformed to the aircraft coordinate system, and the equation of the first line of action of gravity of the rear measuring vehicle is established. Step 11: Increase the height of the aircraft's front end to tilt the aircraft. While the aircraft is tilted, repeat steps 6 to 10 to obtain the second gravity line equation for the front measuring vehicle and the second gravity line equation for the rear measuring vehicle. Step 12: Determine the coordinates of the resultant force point of the front measuring vehicle based on the equations of the first and second lines of action of gravity. ; The coordinates of the resultant force point of the rear measuring vehicle are determined based on the equations of the first and second lines of action of gravity of the rear measuring vehicle. ; Step 13: Combine the coordinates of the resultant force point of the front measuring vehicle and the resultant force point of the rear measuring vehicle to obtain the three-dimensional centroid coordinates of the tested aircraft.

4. The method for measuring the center of mass of a winged aircraft according to claim 3, characterized in that, The transformation matrix from the sensor coordinate system to the reference coordinate system is calculated based on the coordinates of the three reference points on the front measuring vehicle in the reference coordinate system, the coordinates of the geometric center of the tooling base (1) in the reference coordinate system, and the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle in the reference coordinate system; specifically: The geometric center of the tooling base (1) is marked as the coordinates of the reference coordinate system. The first measurement vehicle The coordinates of the bearing point of each weighing sensor in the reference coordinate system are as follows: The coordinates of the three reference points on the front measuring vehicle in the reference coordinate system are marked as follows: ; Plane fitting is performed on the coordinates of the bearing points of the four weighing sensors on the front measuring vehicle to obtain the plane. With the geometric center of the tooling base (1) as the origin of the sensor coordinate system of the front measuring vehicle, the first reference point on the front measuring vehicle is... Projected onto a plane , obtain the projection point Connect the projection points and points , obtained from the projection point Point of view The vector, for the plane For each normal direction, draw a line connecting the normal direction to the projection point. Point of view The dot product of the vectors is used, and the normal direction corresponding to the dot product with a value of 1 is taken as the Z-axis direction of the front measuring vehicle sensor coordinate system. In the reference coordinate system, the unit vector of the Z-axis of the front measuring vehicle sensor coordinate system is... ; The vector pointing from the geometric center of the tooling base (1) to the weighing point of the first sensor on the front measuring vehicle is normalized. The resulting unit vector is the X-axis unit vector of the sensor coordinate system of the front measuring vehicle. In the reference coordinate system, the X-axis unit vector of the sensor coordinate system of the front measuring vehicle is: ; Draw the unit vector along the Z-axis and the X-axis unit vector The vector product of these vectors yields the unit Y-axis vector of the front measuring vehicle's sensor coordinate system in the reference coordinate system. ; The transformation matrix from the sensor coordinate system of the front measuring vehicle to the reference coordinate system. for: in, This represents the transformation matrix from the sensor coordinate system of the front measuring vehicle to the reference coordinate system.

5. The method for measuring the center of mass of a winged aircraft according to claim 4, characterized in that, Establish a set of static moment equilibrium equations in the coordinate system of the front measuring vehicle's sensor, and calculate the coordinates of the projection point of the resultant force point of the front measuring vehicle in a horizontal state; specifically: The static moment equilibrium equations are as follows: in: This indicates that the bearing point of the first weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis; This indicates that the bearing point of the first weighing sensor on the front measuring vehicle is located in the sensor coordinate system Y of the front measuring vehicle. S Coordinates along the axis; This indicates that the bearing point of the second weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis; This indicates that the bearing point of the second weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates that the load-bearing point of the third weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis; This indicates that the bearing point of the third weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates that the bearing point of the fourth weighing sensor on the front measuring vehicle is located in the X coordinate system of the front measuring vehicle. S Coordinates along the axis; This indicates that the load-bearing point of the fourth weighing sensor on the front measuring vehicle is located in the Y-coordinate system of the front measuring vehicle sensor. S Coordinates along the axis; This indicates the difference corresponding to the first weighing sensor on the front measuring vehicle. This indicates the difference between the second weighing sensor on the front measuring vehicle. This indicates the difference corresponding to the third weighing sensor on the front measuring vehicle. This indicates the difference value corresponding to the fourth weighing sensor on the front measuring vehicle; The first line of action of gravity of the front measuring vehicle passes through the point in the coordinate system of the front measuring vehicle's sensor. Since the direction of the line of action of gravity is vertically downward, the first line of action of gravity of the front measuring vehicle must pass through the point in the coordinate system of the front measuring vehicle's sensor. .

6. The method for measuring the center of mass of a winged aircraft according to claim 5, characterized in that, The transformation matrix between the aircraft coordinate system and the sensor coordinate system of the front measuring vehicle is used to transform the coordinates of the projection point of the resultant force point of the front measuring vehicle to the aircraft coordinate system; specifically: in, Point The corresponding coordinates in the spacecraft coordinate system point The corresponding coordinates in the spacecraft coordinate system.

7. The method for measuring the center of mass of a winged aircraft according to claim 6, characterized in that, In step ten, the equation of the first gravity line of action of the forward measuring vehicle is established in the aircraft coordinate system based on the transformation result, specifically as follows: According to the point and points At the corresponding point in the spacecraft coordinate system, establish the equation of the first line of action of gravity for the forward measuring vehicle in the spacecraft coordinate system: in, , and Indicates the directions of the three coordinate axes of the aircraft's coordinate system; The equation of the second line of action of gravity of the front measuring vehicle is: in, and This indicates the coordinates of the two points along the second line of gravity of the forward measuring vehicle in the spacecraft coordinate system.

8. The method for measuring the center of mass of a winged aircraft according to claim 7, characterized in that, The specific process of step twelve is as follows: Determine whether the equations of the first and second lines of action of gravity on the front measuring vehicle intersect; If the equations of the first and second lines of action of gravity on the front measuring vehicle intersect, then the coordinates of the intersection point are the coordinates of the resultant force point of the front measuring vehicle. Simultaneously satisfying the linear equations of the two lines of action of gravity on the front measuring vehicle: If the equations of the first and second lines of action of gravity on the front measuring vehicle do not intersect, meaning the two lines of action of gravity on the front measuring vehicle are skew in space, then the midpoint of the common perpendicular of the first and second lines of action of gravity on the front measuring vehicle is taken as the point of resultant force on the front measuring vehicle. .

9. A method for measuring the center of mass of a winged aircraft according to claim 8, characterized in that, The specific process of step thirteen is as follows: in, Indicates the coordinates of the center of mass of the tested aircraft. This represents the average load measured twice by the four sensors of the front measuring vehicle in both horizontal and tilted states. This represents the average load of the four sensors on the rear measuring vehicle in two measurements, one in a horizontal state and the other in an inclined state. in, , ; , , , and This represents the measurement values ​​from four sensors on the front measurement vehicle when the aircraft is in a horizontal position. , , , and This indicates the readings from four sensors on the front measurement vehicle when the aircraft is tilted. Represents gravitational acceleration; , , , and This indicates the measurement values ​​from four sensors on the vehicle when the aircraft is in a horizontal position. , , , and This indicates the measurement values ​​of the four sensors on the vehicle when the aircraft is tilted.

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