A Pitch Angle Adjustment System and Method Based on a Twin Model of a Helicopter Main Rotor System

Abstract

This invention discloses a pitch angle adjustment system and method based on a twin model of a helicopter main rotor system. The pitch angle adjustment system based on the twin model of a helicopter main rotor system includes: a main rotor structure; a twin model establishment module, the twin model including a model main rotor hub, a model swashplate, a model main reducer, and multiple model rotor arms corresponding to the main rotor structure; a robot simulation module; multiple measuring fixtures, which are respectively installed on multiple rotor arms of the main rotor structure; and a laser tracker, which is suitable for detecting the multiple measuring fixtures to determine the position and attitude of the multiple rotor arms. The pitch angle adjustment system based on the twin model of a helicopter main rotor system according to the embodiments of this invention has the advantages of high automation, high adjustment efficiency, and strong applicability.

Description

Technical Field

[0001] This invention relates to the field of aircraft manufacturing technology, and more specifically, to a pitch angle adjustment system and a pitch angle adjustment method based on a twin model of a helicopter main rotor system. Background Technology

[0002] The helicopter main rotor hub system mainly consists of a control system, actuators, swashplate, pitch control stick, boom, and rotor, which are interconnected mechanically, hydraulically, or electrically to enable helicopter flight operations. With the pitch control stick and swashplate attitudes fixed, different rotor flapping angles will correspond to different blade pitch angles; the nominal blade pitch angle is the blade pitch angle when the boom reaches its upper flapping limit.

[0003] The method for measuring the pitch angle of the helicopter main rotor system in related technologies involves manually raising the rotor arm to the pitch angle measurement position multiple times and using an optical quadrant for measurement and processing. Although this method can meet the accuracy requirements, it is based on traditional instrument readings, requires manual elimination of flapping angle gap, and requires manual calculation to generate the target angle. This method is labor-intensive and cannot achieve full automation.

[0004] Therefore, some pitch angle measurement methods use inertial measurement sensors to automate angle measurement. However, inertial measurement sensors use microelectromechanical devices, which are susceptible to environmental interference and have poor reliability. In addition, manual lifting of the outrigger is still required, resulting in a large workload and high labor intensity. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a pitch angle adjustment system based on a twin model of a helicopter main rotor system. This pitch angle adjustment system based on a twin model of a helicopter main rotor system has the advantages of high automation, high adjustment efficiency, and strong applicability.

[0006] This invention also proposes a method for adjusting the pitch angle based on a twin model of a helicopter main rotor system.

[0007] To achieve the above objectives, according to an embodiment of the first aspect of the present invention, a pitch angle adjustment system based on a twin model of a helicopter main rotor system is proposed. The pitch angle adjustment system includes: a main rotor structure, comprising a main rotor hub, a swashplate, a main reducer, multiple rotor arms, and multiple pitch control rods; the multiple rotor arms are mounted on the main rotor hub; the swashplate includes a fixed swashplate and a rotating swashplate; the main reducer is connected to both the main rotor hub and the fixed swashplate; the lower ends of the multiple pitch control rods are connected to the rotating swashplate, and the upper ends are connected to the multiple rotor arms; and a twin model creation module, used to create a twin model of the main rotor structure. The twin model includes a model main rotor hub, a model swashplate, a model main reducer, and multiple model rotor arms corresponding to the main rotor structure; the model swashplate includes a model fixed swashplate and a model rotating swashplate; and the model main reducer... A rotating joint is provided between the model's main rotor hub and the model's rotor arm. Two rotating joints are provided between each model rotor arm and the model's main rotor hub. A rotating joint is provided between the model's rotating swashplate and the model's fixed swashplate. A translational joint and two rotating joints are provided between the model's fixed swashplate and the model's main reducer. An upper connection point is provided on each model rotor arm corresponding to the position where the rotor arm connects to the pitch control rod. A lower connection point is provided on each model rotating swashplate corresponding to the position where the rotating swashplate connects to the pitch control rod. A robot simulation module is used to import the twin model for simulation and is suitable for controlling the rotating and translational joints of the twin model to simulate the pitch angle adjustment of the twin model. Multiple measuring fixtures are respectively installed on multiple rotor arms of the main rotor structure. A laser tracker is used to detect the multiple measuring fixtures to determine the position and attitude of the multiple rotor arms.

[0008] The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to an embodiment of the present invention can improve the automation level and efficiency of measurement by setting up a laser tracker and measuring fixtures. By setting up a twin model establishment module and a robot simulation module, a twin model of the main rotor structure can be established using the twin model establishment module. During the pitch angle adjustment process, the twin model can be used to replace the main rotor structure for movement, reducing the step of manually lifting the rotor arm to the measurement position, reducing the manual workload of the adjustment process, and improving the adjustment efficiency. By not setting the model pitch-changing tie rod when establishing the twin model, the original parallel mechanism of the main rotor structure is transformed into two serial mechanisms, which facilitates the establishment of a unified robot description and the import of the twin model into the robot simulation module for simulation, thereby improving the applicability of the pitch angle adjustment system based on the twin model of the helicopter main rotor system. It has the advantages of high automation, high adjustment efficiency, and strong applicability.

[0009] In addition, the pitch angle adjustment system based on the twin model of the helicopter main rotor system according to the above embodiments of the present invention may also have the following additional technical features:

[0010] According to one embodiment of the present invention, a plurality of measuring fixtures are respectively disposed on a plurality of rotor arms.

[0011] According to one embodiment of the present invention, a plurality of measuring fixtures are respectively disposed at the outer ends of a plurality of rotor arms.

[0012] According to one embodiment of the present invention, each of the measuring fixtures includes two connecting rods and four target balls. The two connecting rods are parallel to each other and spaced apart and arranged perpendicular to the length direction of the rotor arm. The target balls are provided at both ends of each connecting rod. The laser tracker is adapted to detect the position of the target balls.

[0013] According to one embodiment of the present invention, the connecting rod is fitted into the blade mounting hole of the rotor arm.

[0014] According to one embodiment of the present invention, there are two laser trackers arranged opposite each other on both sides of the main rotor structure.

[0015] According to a second aspect of the present invention, a method for adjusting the pitch angle based on a twin model of a helicopter main rotor system is proposed, employing the pitch angle adjustment system based on a twin model of a helicopter main rotor system as described in a first aspect of the present invention, comprising the following steps:

[0016] S1. Use the laser tracker to establish the measurement field of the main rotor structure, establish the fuselage coordinate system, use the laser tracker to detect the detection fixture and establish the measurement coordinate system of the measurement fixture, obtain the pose state of the measurement coordinate system under the fuselage coordinate system to determine the pose state of the rotor arm of the main rotor structure, and fit the rotor rotation plane of the main rotor structure.

[0017] S2. Based on the detection results of the laser tracker, the pitch angle, flapping angle and rotation angle of the main rotor structure are calculated, and the corresponding translational joints and rotational joints of the twin model are driven to make the twin model and the main rotor structure have the same pose state. The current length of the variable pitch rod of the main rotor structure is calculated by the position of the upper connection point and the lower connection point of the twin model.

[0018] S3. Set the pitch angle in the twin model according to the theoretical pitch angle range, obtain the target length of the variable pitch rod under the corresponding pitch angle, calculate the adjustment amount from the current length to the target length, and obtain the target adjustment range of the adjustment amount;

[0019] S4. If the endpoint values ​​of the target adjustment range have opposite signs, the expected pitch angle value is reached, and proceed to the next step.

[0020] If the endpoint values ​​of the target adjustment range have the same sign, adjust the length of the pitch control rod of the main rotor structure according to the adjustment amount, use the laser tracker to measure the adjusted measuring fixture, map the actual state of the rotor arm of the main rotor structure back to the twin model, update the current length of the pitch control rod of the main rotor structure, and return to step S3.

[0021] S5. Rotate the rotor arm of the main rotor structure to multiple different positions, use the laser tracker to detect the measuring fixture, and verify whether the pitch angle of the main rotor structure and the pitch angle of the twin model meet the tolerance requirements. If they meet the requirements, the adjustment ends; if they do not meet the requirements, return to step S2.

[0022] The pitch angle adjustment method based on a twin model of a helicopter main rotor system according to embodiments of the present invention, by utilizing the pitch angle adjustment system based on a twin model of a helicopter main rotor system as described in the first aspect of the present invention, has the advantages of high automation, high adjustment efficiency, and strong applicability.

[0023] According to an embodiment of the present invention, in step S1, fitting the rotor rotation plane of the main rotor structure includes: sequentially rotating one of the rotor arms to multiple predetermined measurement positions, raising the rotor arm to the upper limit position, using the laser tracker to measure the position and orientation state of the rotating arm using the measuring fixture, and then fitting a circular motion trajectory centered on the main rotor hub axis, establishing a main reducer coordinate system, so that in subsequent steps, the position and orientation data of the main reducer relative to the fuselage can be used to eliminate the deviation of the main reducer relative to the fuselage by calculating the position and orientation data of the fuselage coordinate system relative to the main reducer coordinate system.

[0024] According to one embodiment of the present invention, there are four predetermined measurement positions, and adjacent predetermined measurement positions are rotated 90 degrees.

[0025] According to one embodiment of the present invention, there are two laser trackers. In step S1, after establishing the measurement field of the main rotor structure using the laser trackers, the method further includes: unifying the coordinate systems of the two laser trackers.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0028] Figure 1 This is a schematic diagram of the pitch angle adjustment system based on a twin model of a helicopter main rotor system according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the kinematic relationship of a pitch angle adjustment system based on a twin model of a helicopter main rotor system according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the inverse kinematic relationship of the pitch angle adjustment system based on a twin model of the helicopter main rotor system according to an embodiment of the present invention.

[0031] Figure 4 This is a flowchart of a pitch angle adjustment method based on a twin model of a helicopter main rotor system according to an embodiment of the present invention.

[0032] Figure reference numerals: Pitch angle adjustment system based on twin model of helicopter main rotor system 1, main rotor structure 10, main rotor hub 11, swashplate 12, fixed swashplate 121, rotating swashplate 122, main reducer 13, rotor arm 14, pitch control rod 15, measuring fixture 20, connecting rod 21, target ball 22, laser tracker 30. Detailed Implementation

[0033] This application is based on the inventor's discoveries and understanding of the following facts and problems:

[0034] The method for measuring the pitch angle of the helicopter main rotor system in related technologies involves manually raising the rotor arm to the pitch angle measurement position multiple times and using an optical quadrant for measurement and processing. Although this method can meet the accuracy requirements, it is based on traditional instrument readings, requires manual elimination of flapping angle gap, and requires manual calculation to generate the target angle, making it impossible to achieve full automation.

[0035] Therefore, some pitch angle measurement methods use inertial measurement sensors to automate angle measurement. However, inertial measurement sensors use microelectromechanical devices, which are susceptible to environmental interference and have poor reliability. In addition, manual lifting of the boom is still required, which is a lot of work.

[0036] Some methods for measuring the pitch angle of helicopter main rotor systems in related technologies use twin models to simulate the main rotor structure. However, due to the complexity of the helicopter main rotor system and the high precision requirements, especially the parallel mechanism consisting of the main reducer, main rotor hub, rotating support arm and swashplate, it is difficult to establish a unified robot description and directly apply it to robot simulation software, which affects the feasibility of using twin models for simulation measurement.

[0037] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] The following description, with reference to the accompanying drawings, describes a pitch angle adjustment system 1 based on a twin model of a helicopter main rotor system according to an embodiment of the present invention.

[0041] like Figures 1-4 As shown, the pitch angle adjustment system 1 based on the twin model of the helicopter main rotor system according to an embodiment of the present invention includes a main rotor structure 10, a twin model establishment module, a robot simulation module, multiple measuring fixtures 20 and a laser tracker 30.

[0042] The main rotor structure 10 includes a main rotor hub 11, a swashplate 12, a main reducer 13, multiple rotor arms 14, and multiple pitch control rods 15. The multiple rotor arms 14 are mounted on the main rotor hub 11. The swashplate 12 includes a fixed swashplate 121 and a rotating swashplate 122. The main reducer 13 is connected to the main rotor hub 11 and the fixed swashplate 122 respectively. The lower ends of the multiple pitch control rods 15 are all connected to the rotating swashplate, and the upper ends are respectively connected to the multiple rotor arms 14.

[0043] The twin model creation module is used to create a twin model of the main rotor structure 10. The twin model includes a model main rotor hub, a model swashplate, a model main reducer, and multiple model rotor arms corresponding to the main rotor structure. The model swashplate includes a model fixed swashplate and a model rotating swashplate. A rotational joint is provided between the model main reducer and the model main rotor hub. Two rotational joints are provided between each model rotor arm and the model main rotor hub. A rotational joint is provided between the model rotating swashplate and the model fixed swashplate. A translational joint and two rotational joints are provided between the model fixed swashplate and the model main reducer. An upper connection point is provided on each model rotor arm corresponding to the position where the rotor arm connects to the pitch control rod. A lower connection point is provided on each model rotating swashplate corresponding to the position where the rotating swashplate connects to the pitch control rod.

[0044] The robot simulation module is used to import the twin model for simulation and is suitable for controlling the rotational joints and translational joints of the twin model to simulate the pitch angle adjustment of the twin model.

[0045] Multiple measuring fixtures 20 are respectively installed on multiple rotor arms 14 of the main rotor structure 10.

[0046] The laser tracker 30 is suitable for detecting multiple measuring fixtures 20 to determine the position and orientation of multiple rotor arms 14.

[0047] Those skilled in the art will understand that the connection relationships and transmission methods of the various structures of the main rotor structure 10 can be set according to actual needs.

[0048] Specifically, the main rotor hub 11 and the rotating swashplate 122 are driven by the rotor main shaft (not shown) to provide the power source.

[0049] The main rotor structure 10 has a parallel mechanism consisting of a main reducer 13, a main rotor hub 11, a rotor arm 14, and a swashplate 12. By not setting a model pitch-variable tie rod when establishing the twin model, and transforming the original parallel mechanism into two serial mechanisms, "from the model main reducer to the model main rotor hub and then to the model rotor arm" and "from the model main reducer to the model main rotor hub and then to the model swashplate", and designing the length constraint of the imaginary connection line between the upper connection point and the lower connection point, an imaginary pitch-variable tie rod is formed to establish a unified robot description.

[0050] The rotational joint between the model's main reducer and the model's main rotor hub is shared by two cascaded mechanisms to simulate the rotation of the rotor arms 14 and swashplate 12 on the main rotor hub 11 around the axis of the main reducer 13. Two rotational joints between each model rotor arm and the model's main rotor hub are used to simulate the flapping motion and pitch adjustment motion of the rotor arms 14. The translational joint and two rotational joints between the model's rotating swashplate and the model's fixed swashplate are used to simulate the vertical rise, roll, and pitch motions of the rotating swashplate 122, respectively.

[0051] For example, the robot simulation module can be a device running robot simulation software. This machine simulation software can be Mujoco, Pybullet, Gazebo, etc.

[0052] The laser tracker 30 can detect and measure the pose of the tooling 20, thereby obtaining the pose state of the corresponding rotor arm 14.

[0053] The following is for reference. Figures 1-4 The adjustment process of a pitch angle adjustment system 1 based on a twin model of a helicopter main rotor system according to some examples of the present invention is described.

[0054] Establishment of the measurement system and fitting of the rotation plane: The laser tracker is used to establish the measurement field of the main rotor structure, the laser tracker is used to detect the position and orientation of the rotor arm of the main rotor structure by detecting the detection fixture, and the rotor rotation plane of the main rotor structure is fitted.

[0055] Virtual-real mapping: Based on the detection results of the laser tracker, the pitch angle, flapping angle and rotation angle of the main rotor structure are calculated, and the corresponding translational joints and rotational joints of the twin model are driven to make the twin model and the main rotor structure have the same pose state. The current length of the pitch control rod of the main rotor structure is calculated by the position of the upper connection point and the lower connection point of the twin model.

[0056] Pitch rod adjustment amount generation: Set the pitch angle in the twin model according to the theoretical pitch angle range, obtain the target length of the variable pitch tie rod under the corresponding pitch angle, calculate the adjustment amount from the current length to the target length, and obtain the target adjustment range of the adjustment amount;

[0057] Rod adjustment and measurement: If the endpoint values ​​of the target adjustment range have opposite signs, the desired pitch angle is reached, and the next step is performed; if the endpoint values ​​of the target adjustment range have the same sign, the length of the variable pitch rod of the main rotor structure is adjusted according to the adjustment amount, the laser tracker is used to measure the adjusted measuring fixture, the actual state of the rotor arm of the main rotor structure is mapped back to the twin model, the current length of the variable pitch rod of the main rotor structure is updated, and the process returns to the previous step.

[0058] Pitch angle verification: Rotate the rotor arm of the main rotor structure to multiple different positions, use the laser tracker to detect the measuring fixture, and verify whether the pitch angle of the main rotor structure and the pitch angle of the twin model meet the tolerance requirements. If they meet the requirements, the adjustment ends; if they do not meet the requirements, return to the "virtual-real mapping" step.

[0059] According to an embodiment of the present invention, the pitch angle adjustment system 1 based on a twin model of a helicopter main rotor system can obtain the position and attitude state of the corresponding rotor arm 14 by setting up a laser tracker 30 and a measuring fixture 20, and using the laser tracker 30 to detect the pose of the measuring fixture 20. Compared with the manual measurement method in related technologies, this can improve the automation level of measurement and improve measurement efficiency.

[0060] Furthermore, by setting up a twin model creation module and a robot simulation module, a twin model of the main rotor structure 10 can be created using the twin model creation module. This twin model is then imported into the robot simulation module, which controls the joints of the twin model, simulating the pitch angle adjustment process of the main rotor structure 10 through the movement of the corresponding joints. In this way, during the pitch angle adjustment process, the twin model can replace the main rotor structure 10 in movement, reducing the need for manual assistance in raising the rotor arm 14 to the measurement position, thus reducing the manual workload of the adjustment process and improving adjustment efficiency.

[0061] Furthermore, by not setting a model pitch control rod when establishing the twin model, the original parallel mechanism of the main rotor structure 10 is transformed into two serial mechanisms: "from the model main reducer to the model main rotor hub and then to the model rotor arm" and "from the model main reducer to the model main rotor hub and then to the model swashplate". The length constraint of the imaginary connection line between the upper connection point and the lower connection point is designed to form an imaginary pitch control rod. This facilitates the establishment of a unified robot description. Compared with the twin model measurement method in related technologies, it is easier to import the twin model into the robot simulation module for simulation, thereby improving the applicability of the blade pitch angle adjustment system 1 based on the twin model of the helicopter main rotor system.

[0062] Therefore, the pitch angle adjustment system 1 based on the twin model of the helicopter main rotor system according to the present invention has the advantages of high automation, high adjustment efficiency and strong applicability.

[0063] The following description, with reference to the accompanying drawings, describes a pitch angle adjustment system 1 based on a twin model of a helicopter main rotor system according to a specific embodiment of the present invention.

[0064] In some specific embodiments of the present invention, such as Figures 1-4 As shown, the pitch angle adjustment system 1 based on the twin model of the helicopter main rotor system according to an embodiment of the present invention includes a main rotor structure 10, a twin model establishment module, a robot simulation module, multiple measuring fixtures 20 and a laser tracker 30.

[0065] Advantageously, such as Figure 1 and Figure 2 As shown, multiple measuring fixtures 20 are correspondingly mounted on multiple rotor arms 14. This facilitates the laser tracker 30 in measuring the position and orientation of each rotor arm 14.

[0066] More advantageously, such as Figure 1 and Figure 2 As shown, multiple measuring fixtures 20 are respectively disposed at the outer ends of multiple rotor arms 14. This can improve the degree of positional change of the measuring fixtures 20 when the rotor arms 14 move, and further facilitate the acquisition of the positional state of the rotor arms 14 by detecting the measuring fixtures 20.

[0067] Specifically, such as Figure 1 and Figure 2 As shown, each measuring fixture 20 includes two connecting rods 21 and four target balls 22. The two connecting rods 21 are parallel to each other and spaced apart, and are arranged perpendicular to the length direction of the rotor arm 14. Target balls 22 are provided at both ends of each connecting rod 21. The laser tracker 30 is adapted to detect the position of the target balls 22. In this way, the relative position of the four target balls 22 can be used to reflect the pose state of the measuring fixture 20, thereby reflecting the pose state of the rotor arm 14.

[0068] More specifically, such as Figure 1 and Figure 2 As shown, the connecting rod 21 fits into the blade mounting hole of the rotor arm 14. This facilitates the installation of the measuring fixture 20.

[0069] Optionally, such as Figure 1 As shown, there are two laser trackers 30, which are arranged opposite each other on both sides of the main rotor structure 10. This improves the accuracy and reliability of the measurement fixture 20 and avoids measurement blind spots.

[0070] Specifically, the pitch angle adjustment system 1 based on the twin model of the helicopter main rotor system can also use computing devices such as computers for data interaction and processing.

[0071] The following describes a pitch angle adjustment method based on a twin model of a helicopter main rotor system according to an embodiment of the present invention. The pitch angle adjustment method based on a twin model of a helicopter main rotor system according to an embodiment of the present invention employs a pitch angle adjustment system 1 based on a twin model of a helicopter main rotor system according to the above embodiment of the present invention, and includes the following steps:

[0072] S1. Use the laser tracker to establish the measurement field of the main rotor structure, establish the fuselage coordinate system, use the laser tracker to detect the detection fixture and establish the measurement coordinate system of the measurement fixture, obtain the pose state of the measurement coordinate system under the fuselage coordinate system to determine the pose state of the rotor arm of the main rotor structure, and fit the rotor rotation plane of the main rotor structure.

[0073] S2. Based on the detection results of the laser tracker, the pitch angle, flapping angle and rotation angle of the main rotor structure are calculated, and the corresponding translational joints and rotational joints of the twin model are driven to make the twin model and the main rotor structure have the same pose state. The current length of the variable pitch rod of the main rotor structure is calculated by the position of the upper connection point and the lower connection point of the twin model.

[0074] S3. Set the pitch angle in the twin model according to the theoretical pitch angle range, obtain the target length of the variable pitch rod under the corresponding pitch angle, calculate the adjustment amount from the current length to the target length, and obtain the target adjustment range of the adjustment amount;

[0075] S4. If the endpoint values ​​of the target adjustment range have opposite signs, the expected pitch angle value is reached, and proceed to the next step.

[0076] If the endpoint values ​​of the target adjustment range have the same sign, adjust the length of the pitch control rod of the main rotor structure according to the adjustment amount, use the laser tracker to measure the adjusted measuring fixture, map the actual state of the rotor arm of the main rotor structure back to the twin model, update the current length of the pitch control rod of the main rotor structure, and return to step S3.

[0077] S5. Rotate the rotor arm of the main rotor structure to multiple different positions, use the laser tracker to detect the measuring fixture, and verify whether the pitch angle of the main rotor structure and the pitch angle of the twin model meet the tolerance requirements. If they meet the requirements, the adjustment ends; if they do not meet the requirements, return to step S2.

[0078] Specifically, Figure 2 In the process, the fuselage coordinate system p and the main reducer coordinate system t do not coincide due to the influence of the installation angle. The main reducer coordinate system t and the rotor hub coordinate system r are only affected by the rotation angle φ around the rotor main shaft. The rotor hub coordinate system r and the measuring coordinate system m of the support arm are only affected by the pitch angle α and the flapping angle β. Figure 3 In the diagram, when the rotation angle φ is set, the O, R, W, and M systems will all rotate around the z-axis of the T system; when the flapping angle β is set, the R and W systems will all rotate around the y-axis of the O system; when the pitch angle α is set, the R system will rotate around its own x-axis, while the W system will remain stationary. This means the W system only reflects the effect of the flapping angle, while the R system reflects the combined effect of the flapping and pitch angles, and the x-axis of the R and W systems will always coincide. The M system will always be rigidly connected to the R system, meaning that the representation of M in the R system does not change with the attitude of the R system.

[0079] The basic rotation matrix is ​​defined as follows: Let the rotation angle be φ, then the matrix for rotating about its own x-axis is R. X (φ), the matrix of rotation about its own y-axis is R. y (φ), the matrix of rotation about its own z-axis is R. z (φ), defined here:

[0080]

[0081] Step S1 involves establishing the measurement system and fitting the rotation plane. After properly arranging two laser trackers, the measurement field of the main rotor system is established. The measurement coordinate system of the two trackers is unified using the joint space precision measurement network control technology function built into the laser tracker software system. Four target balls symmetrically mounted are installed using the blade mounting holes at the end of the rotating arm. Positioning pins are used to ensure positioning accuracy. After calibration, the spatial pose of the target balls of the measurement fixture in the fuselage coordinate system p can be obtained through the laser tracker.

[0082] Because the main reducer has a certain pose deviation relative to the fuselage, directly calculating the pitch angle by measuring the angle on the main rotor hub using a laser tracker cannot yield the actual value. Therefore, it is necessary to fit the rotor rotation plane to eliminate the influence of the angular deviation on the measurement results. After calibrating the measurement fixture, with the swashplate reference position, a designated support arm is rotated sequentially to four designated measurement positions, such as 0 degrees, 90 degrees, 180 degrees, and 270 degrees. It is then raised to its upper limit position, and the pose of the rotating support arm is obtained using a laser tracker, thereby fitting the motion trajectory. This trajectory is circular, with its axis pointing towards the main rotor hub, and a main reducer coordinate system t is established based on this. During subsequent measurements, the pose data T relative to the main reducer coordinate system t is calculated. mt =T mp T pt This will eliminate the deviation and yield the actual value.

[0083] Step S2 involves virtual-real mapping. Based on the measurement results, the calculation methods for each angle are as follows:

[0084] Let the attitude rotation matrix of the measurement coordinate system m relative to the main reducer coordinate system t be: The following derivation only considers attitude information, not position information. The measurement coordinate system M can be considered as obtained from the T system through a series of coordinate transformations: the T system is rotated about the z-axis by an angle φ to obtain the O system; the O system is rotated about the y-axis by a flapping angle β to obtain the W system; and the W system is rotated about the x-axis by a pitch angle α to obtain the R system. The M system and the R system are fixed together and have the same attitude. Since all rotations are relative to the motion coordinate system, we can obtain:

[0085]

[0086] After multiplying the matrices, we get:

[0087]

[0088] Considering its inverse solution problem, equation (1.2) can be simplified to:

[0089]

[0090] Combining equations (1.2) and (1.3), we can derive:

[0091]

[0092] If cosβ≠0, then the arctangent expressions for each angle can be obtained:

[0093]

[0094] The radical operation in equation (1.4) has two solutions, and one of them is always chosen from (-90°, 90°). If β = ±90° and cosβ = 0, then the inverse solution of equation (1.5) degenerates, meaning that only α and β can be solved. The sum or difference is usually chosen. The value is 0, so the solution is as follows:

[0095] If β = 90°, then:

[0096]

[0097] If β = -90°, then:

[0098]

[0099] Based on the above derivation, the pitch angle α, flapping angle β, and rotation angle can be obtained.

[0100] After obtaining the actual values ​​of the pitch angle and flapping angle, the corresponding joints in the virtual environment are driven to the same position. The current pitch lever length Lm can then be calculated from the positions of the upper and lower connection points in the twin model in the simulator. The other five swivel arms only need to be raised once to their upper limit position to obtain the current swivel arm's pitch angle, flapping angle, and pitch lever length. Compared to existing measurement methods, during subsequent measurement and adjustment, workers do not need to raise the swivel arms again. The pitch lever adjustment amount can be obtained through virtual-real mapping and calculation for measurement and adjustment. This digital twin measurement method only requires workers to assist in raising the swivel arms during calibration, greatly reducing the worker's workload.

[0101] Step S3 generates the lever adjustment amount. Assuming the tilting plate is in its reference state, the theoretically permissible pitch angle range for different rotating arms is [α]. min ,α max In the virtual environment, the corresponding boom pitch angle is set to α. min α max Read the corresponding rod length l min , l max Therefore, the adjustment amount of the lever length under the current state can be obtained as follows:

[0102] △l min ,Δl max =l min -lm , l max -l m ,

[0103] The rod length adjustment range is [Δl] min , Δl max If the endpoint values ​​of the interval have different signs, the desired pitch angle is reached, the adjustment process is completed, and the process proceeds to S5 for verification; if the endpoint values ​​of the interval have the same sign, further adjustment is performed.

[0104] S4 involves adjusting and measuring the tie rod. The midpoint of the adjustment range generated in the previous step is used as the target adjustment value. Workers use vernier calipers to measure, mark, and adjust the change in tie rod length. After adjustment, a laser tracker is used to measure the corresponding rotating arm's measuring fixture in the non-lifted state, and the actual state is mapped back to the virtual model in the simulator to obtain the new rod length l. m =l m Then return to S3 to generate the adjustment amount and determine the adjustment state.

[0105] S5 is for pitch angle verification. After adjusting the pitch angle at one position, the outrigger is rotated to the other three calibration positions. A laser tracker is used to measure the corresponding measuring fixture of the rotating outrigger in the non-lifted state, and the actual state is mapped back to the virtual model in the simulator to obtain the new rod length l. m =l m Set the virtual model corresponding to the rotating arm in the simulator to the upper limit, read the pitch angle, and verify whether it is within the tolerance range. If it meets the requirements, the adjustment ends; otherwise, return to S2.

[0106] After adjusting the swashplate's reference position, the verification is performed under the conditions of swashplate collective pitch change and periodic pitch change. The verification method is similar to the above steps, except that the swashplate attitude needs to be obtained.

[0107] The pitch angle adjustment method based on a twin model of a helicopter main rotor system according to embodiments of the present invention, by utilizing the pitch angle adjustment system 1 based on a twin model of a helicopter main rotor system according to the above embodiments of the present invention, has the advantages of high automation, high adjustment efficiency, and strong applicability.

[0108] Specifically, in step S1, fitting the rotor rotation plane of the main rotor structure includes: sequentially rotating one of the rotor arms to multiple predetermined measurement positions, raising the rotor arm to its upper limit, using the laser tracker to measure the position and orientation of the rotating arm using the measuring fixture, and then fitting a circular motion trajectory centered on the main rotor hub axis to establish a main reducer coordinate system. This allows for the elimination of the main reducer's deviation relative to the fuselage during subsequent measurements by calculating the position and orientation data of the fuselage coordinate system relative to the main reducer coordinate system. This facilitates fitting the rotor rotation plane of the main rotor structure.

[0109] Optionally, there are four predetermined measurement positions, with each adjacent predetermined measurement position rotated 90 degrees. For example, these can be four positions: 0 degrees, 90 degrees, 180 degrees, and 270 degrees. This further facilitates fitting the rotor's rotation plane and improves the reliability of the fitting.

[0110] Advantageously, two laser trackers are used. In step S1, after establishing the measurement field of the main rotor structure using the laser trackers, the method further includes unifying the coordinate systems of the two laser trackers. This improves the accuracy and reliability of the measurement and avoids measurement blind spots.

[0111] Other configurations and operations of the pitch angle adjustment method based on a twin model of a helicopter main rotor system according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0112] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0113] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A pitch angle adjustment system based on a twin model of a helicopter main rotor system, characterized in that, include: The main rotor structure includes a main rotor hub, a swashplate, a main reducer, multiple rotor arms, and multiple pitch control rods. The multiple rotor arms are mounted on the main rotor hub. The swashplate includes a fixed swashplate and a rotating swashplate. The main reducer is connected to the main rotor hub and the fixed swashplate respectively. The lower ends of the multiple pitch control rods are all connected to the rotating swashplate, and the upper ends are all connected to the multiple rotor arms respectively. A twin model creation module is used to create a twin model of the main rotor structure. The twin model includes a model main rotor hub, a model swashplate, a model main reducer, and multiple model rotor arms corresponding to the main rotor structure. The model swashplate includes a fixed model swashplate and a rotating model swashplate. A rotational joint is provided between the model main reducer and the model main rotor hub. Each model rotor arm is provided with two rotational joints to the model main rotor hub. A rotational joint is provided between the rotating model swashplate and the fixed model swashplate. A translational joint and two rotational joints are provided between the fixed model swashplate and the model main reducer. An upper connection point is provided on each model rotor arm corresponding to the position where the rotor arm connects to the pitch control rod. A lower connection point is provided on the rotating model swashplate corresponding to the position where the rotating model swashplate connects to the pitch control rod. A robot simulation module is used to import the twin model for simulation and is suitable for controlling the rotational joints and translational joints of the twin model to simulate the pitch angle adjustment of the twin model. Multiple measuring fixtures are respectively mounted on multiple rotor arms of the main rotor structure; A laser tracker adapted to detect multiple of the measuring fixtures to determine the pose state of multiple rotor arms.

2. The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to claim 1, characterized in that, The various measuring fixtures are respectively installed on the various rotor arms.

3. The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to claim 1, characterized in that, The multiple measuring fixtures are respectively located at the outer ends of the multiple rotor arms.

4. The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to claim 1, characterized in that, Each of the measuring fixtures includes two connecting rods and four target balls. The two connecting rods are parallel to each other and spaced apart, and are arranged perpendicular to the length direction of the rotor arm. The target balls are provided at both ends of each connecting rod. The laser tracker is adapted to detect the position of the target balls.

5. The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to claim 4, characterized in that, The connecting rod fits into the blade mounting hole of the rotor arm.

6. The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to claim 1, characterized in that, Two laser trackers are arranged opposite each other on both sides of the main rotor structure.

7. A method for adjusting the rotor pitch angle based on a twin model of a helicopter main rotor system, characterized in that, The pitch angle adjustment system based on a twin model of a helicopter main rotor system according to any one of claims 1-6 includes the following steps: S1. Use the laser tracker to establish the measurement field of the main rotor structure, establish the fuselage coordinate system, use the laser tracker to detect the detection fixture and establish the measurement coordinate system of the measurement fixture, obtain the pose state of the measurement coordinate system under the fuselage coordinate system to determine the pose state of the rotor arm of the main rotor structure, and fit the rotor rotation plane of the main rotor structure. S2. Based on the detection results of the laser tracker, the pitch angle, flapping angle and rotation angle of the main rotor structure are calculated, and the corresponding translational joints and rotational joints of the twin model are driven to make the twin model and the main rotor structure have the same pose state. The current length of the variable pitch rod of the main rotor structure is calculated by the position of the upper connection point and the lower connection point of the twin model. S3. Set the pitch angle in the twin model according to the theoretical pitch angle range, obtain the target length of the variable pitch rod under the corresponding pitch angle, calculate the adjustment amount from the current length to the target length, and obtain the target adjustment range of the adjustment amount; S4. If the endpoint values ​​of the target adjustment range have opposite signs, the expected pitch angle value is reached, and proceed to the next step. If the endpoint values ​​of the target adjustment range have the same sign, adjust the length of the pitch control rod of the main rotor structure according to the adjustment amount, use the laser tracker to measure the adjusted measuring fixture, map the actual state of the rotor arm of the main rotor structure back to the twin model, update the current length of the pitch control rod of the main rotor structure, and return to step S3. S5. Rotate the rotor arm of the main rotor structure to multiple different positions, use the laser tracker to detect the measuring fixture, and verify whether the pitch angle of the main rotor structure and the pitch angle of the twin model meet the tolerance requirements. If they meet the requirements, the adjustment ends; if they do not meet the requirements, return to step S2.

8. The method for adjusting the blade pitch angle based on a twin model of a helicopter main rotor system according to claim 7, characterized in that, In step S1, fitting the rotor rotation plane of the main rotor structure includes: One of the rotor arms is rotated sequentially to multiple predetermined measurement positions, and the rotor arm is raised to its upper limit. The laser tracker is used to measure the position and orientation of the rotating arm using the measuring fixture. Then, a circular motion trajectory centered on the main rotor hub axis is fitted, and a main reducer coordinate system is established. In subsequent steps, the position and orientation data of the main reducer relative to the fuselage are used to eliminate the deviation of the main reducer relative to the fuselage by calculating the position and orientation data of the fuselage coordinate system relative to the main reducer coordinate system.

9. The method for adjusting the blade pitch angle based on a twin model of a helicopter main rotor system according to claim 8, characterized in that, The predetermined measurement positions are four in number, and each pair of adjacent predetermined measurement positions is rotated 90 degrees.

10. The method for adjusting the rotor pitch angle based on a twin model of a helicopter main rotor system according to claim 7, characterized in that, There are two laser trackers. In step S1, after establishing the measurement field of the main rotor structure using the laser trackers, the method further includes unifying the coordinate systems of the two laser trackers.

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