CN113358337A - Loading method and loading device for aircraft wing static strength experiment - Google Patents

Abstract

The invention provides a loading method and a loading device for an aircraft wing static strength experiment, which comprise a two-rotation two-movement four-freedom-degree parallel loading device and a two-level lever system. The parallel loading device comprises a fixed platform, a loading platform, a force sensor, a first motion branch, a second motion branch, a third motion branch and a fourth motion branch, wherein the loading platform is connected with the fixed platform through the four motion branches, two secondary lever systems are positioned on the loading platform and symmetrically distributed on two sides above the loading platform, each secondary lever system is provided with four loading point positions, and the whole device is totally provided with eight loading point positions. Force sensors are arranged on the four movement branches. The driving of the four movement branches selects to drive the moving pair and adopts a hydraulic cylinder to drive. The invention can simultaneously adjust the direction and the magnitude of the loading force in the loading process of the wing static force experiment, thereby effectively reducing the experimental error.

Description

Loading method and loading device for aircraft wing static strength experiment

Technical Field

The invention relates to the field of aviation experiment tests, in particular to a loading method and a loading device for an aircraft wing static strength experiment based on a parallel mechanism and a lever system.

Background

The full-static force test in the ground strength test of the airplane structure is an important test project for checking the characteristics of the airplane structure, such as bearing capacity, rigidity and the like. In order to simulate the loading force applied to the wing in flight in the full-static experiment, the loading direction needs to be adjusted to ensure that the loading force is vertical to the surface of the wing.

At present, a loading device for carrying out static force experiments on airplane wings is mainly a rubberized fabric tape-lever loading system, and other common wing static force loading modes comprise a clamping board loading mode and an air bag loading mode. The adhesive tape-lever system requires that the adhesive tape is adhered on the surface of the wing, and then the lever system is used for carrying out multi-stage loading on the wing. The adhesive tape-lever system can better simulate the aerodynamic load borne by the wing, the defect is that the strength of the wing surface layer made of composite materials is possibly low, unnecessary damage to the wing surface is caused, and in addition, the loading direction cannot be kept perpendicular to the wing due to large wing deformation near the wing end, so that errors occur in the experiment. Plate loading is primarily the clamping of the wing by the clip, which can be simulated by pulling the clip upwards, but the clip is generally heavy and complex to install. The airbag loading is a novel loading technology, the pneumatic load of the wing in actual flight can be more accurately simulated, but the airbag loading cost is high; the types of wings are diversified, the air bags are not standardized, and the universality is poor; sharp objects or over-rated inflation of the wing structure surface can cause sudden bursts on loading; the measurement of the strain is also a problem when the bladder is fully in contact with the wing surface when loaded. The existing loading technology can not meet static test conditions of the wings of the airplane with large aspect ratio or generate errors. The experimental results are greatly influenced.

Disclosure of Invention

The invention provides a four-degree-of-freedom wing experiment loading device, and aims to solve the problems that the loading direction cannot be guaranteed to be always perpendicular to the surface of a wing and the loading force is uniformly distributed when other loading modes are used for carrying out a wing static test.

The invention provides a loading method for an aircraft wing static strength experiment, which comprises the following steps: s1, theoretically analyzing the wings, determining required loading point positions, calculating the theoretical loading force of each loading point position in the loading experiment process, and calculating the resultant force of the theoretical loading forces of each group of loading point positions in the experiment process, wherein each group of loading point positions has eight loading points, and the resultant force of the loading forces of each eight loading point positions is the loading force required to be applied by the loading platform; predicting the deformation condition of the wing through theoretical calculation, determining the displacement required by a loading device, and planning the motion path of the movable platform in an actual loading experiment; s2, starting loading, driving the movable platform to move according to the path in the step S1, detecting the magnitude and direction of the reaction force of the airplane wings on the loading platform in real time through the force sensor in the movement branch, and detecting the deformation condition of the wings in real time in the experimental process; s3, judging the loading force of the wing after detecting the wing deformation condition, calculating the angle difference between the loading force and the wing surface, and calculating the angle to be adjusted according to the measured wing deformation condition and the posture of the wing experiment loading device when the loading force is not vertical to the wing surface in the experiment; s4, after the angle required to be adjusted is calculated, the displacement required by each actuator cylinder can be calculated through inverse kinematics solution, and the adjustment of the direction of the loading force is completed; s5, after the operation of the step S4 is completed, if the loading force of the wing loading device and the surface normal direction of the wing still have errors, the step S3 and the step S4 are repeated until the accuracy requirement is met.

The invention provides a loading device based on the loading method of the aircraft wing static strength experiment, which comprises a parallel loading device and a secondary lever system, wherein the parallel loading device is a four-degree-of-freedom mechanism with two-rotation and two-shift functions, and comprises a fixed platform, a loading platform, a force sensor, a first motion branch, a second motion branch, a third motion branch and a fourth motion branch; the fixed platform is connected with the movable platform through four movement branches; a first end of the first motion branch is connected with a first end of the fixed platform, a first end of the second motion branch is connected with a second end of the fixed platform, a first end of the third motion branch is connected with a third end of the fixed platform, a first end of the fourth motion branch is connected with a fourth end of the fixed platform, a second end of the first motion branch is connected with a first end of the loading platform, a second end of the second motion branch is connected with a second end of the loading platform, a second end of the third motion branch is connected with a third end of the loading platform, a second end of the fourth motion branch is connected with a fourth end of the loading platform, and the force sensors are respectively positioned on the first motion branch, the second motion branch, the third motion branch and the fourth motion branch; the two secondary lever systems are positioned above the loading platform and symmetrically distributed at two ends of the loading platform, the rotation axes of the first-stage lever systems are parallel and collinear, the rotation axes of the first-stage lever systems are parallel and coplanar with the ball pair connecting lines of the first movement branch and the third movement branch, the second-stage lever paths are symmetrically distributed, and the rotation axes are perpendicular to the rotation axes of the first-stage levers.

Preferably, the first motion branch and the third motion branch have the same structure, the second motion branch and the fourth motion branch have the same structure and each include a revolute pair, a revolute pair and a ball pair, a first end of the revolute pair is connected with the fixed platform, a second end of the revolute pair is connected with a first end of the revolute pair, a second end of the revolute pair is connected with a first end of the ball pair, and a second end of the ball pair is connected with the loading platform; the force sensor is positioned between the moving pair and the ball pair.

Preferably, the second motion branch and the fourth motion branch have the same structure, and the second motion branch and the fourth motion branch have the same structure and each include a U pair, a moving pair and a ball pair, a first end of the U pair is connected with the fixed platform, a second end of the U pair is connected with a first end of the moving pair, a second end of the moving pair is connected with a first end of the ball pair, and a second end of the ball pair is connected with the loading platform; the force sensor is positioned between the moving pair and the ball pair.

Preferably, the revolute pair of the first kinematic branch, the U pair of the second kinematic branch, the revolute pair of the first kinematic branch and the U pair of the second kinematic branch are coplanar and parallel to the fixed platform, the revolute pair of the first kinematic branch, the U pair of the second kinematic branch, the revolute pair of the first kinematic branch and the U pair of the second kinematic branch are distributed in a diamond shape, and the rotation axes of the revolute pairs of the first kinematic branch and the third kinematic branch are parallel to each other and perpendicular to the connecting line between the revolute pair of the first kinematic branch and the U pair of the second kinematic branch; the ball pairs in the four movement branches are coplanar, the plane formed by the four ball pairs is parallel to the loading platform, and the four ball pairs are distributed in a diamond shape.

Compared with the prior art, the invention has the following beneficial effects:

(1) the four-degree-of-freedom parallel mechanism can realize that the movable platform completes two-rotation two-shift movement, and can automatically adjust the direction of a loading force during loading so as to meet the requirement of static force experiments of airplane wings, reduce experiment errors and effectively improve experiment precision;

(2) the parallel device is adopted for loading, and compared with a loading device for a wing static strength experiment, the loading device has higher stability and rigidity, and the loading device cannot lose stability when the wing breaks.

Drawings

FIG. 1 is a schematic view of a loading device for a wing static strength experiment based on a parallel mechanism and a lever system;

FIG. 2 is a schematic structural diagram of a first motion branch and a third motion branch;

FIG. 3 is a schematic structural diagram of a second motion branch and a fourth motion branch;

FIG. 4 is a schematic view of a ball set;

FIG. 5 is a schematic view of a lever system;

FIG. 6 is a schematic view of a primary beam of the lever system;

FIG. 7 is a schematic view of a secondary beam of the lever system;

FIG. 8 is a schematic view of an installation of a loading device for a wing static strength experiment based on a parallel mechanism and a lever system;

FIG. 9 is a loading diagram.

Reference numerals:

1. fixing a platform; 2. a first motion branch; 3. a second motion branch; 4. a third motion branch; 5. a fourth motion branch; 6. loading a platform; 7. a lever system; 8. a revolute pair; 9. a sliding pair; 10. a first force sensor; 11. a first ball pair; 12. a U pair; 13. a sliding pair; 14. a second force sensor; 15. a second ball pair; 16. a first rotating pair in the ball pair; 17. a second revolute pair in the ball pair; 18. a third revolute pair in the ball pair; 19. a primary lever beam; 20. a secondary lever beam; 21. loading a panel; 22. an airfoil; 23. an experiment loading device; 191. a connecting hole of the first-level lever beam and the loading platform; 192. a first connection hole; 201. a second connection hole; 202. a second shaft bore.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments that can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

A loading device for an aircraft wing static strength experiment based on a parallel mechanism and a lever system is shown in figures 1-9, wherein anexperiment loading device 23 comprises a two-rotation two-movement four-freedom-degree parallel loading device and a two-level lever system 7, and the two-level lever system is arranged above the two-rotation two-movement four-freedom-degree parallel loading device. The parallel loading device comprises a fixed platform 1, aloading platform 6, afirst motion branch 2, a second motion branch 3, a third motion branch 4 and a fourth motion branch 5.

The fixed platform and the movable platform in the two-rotation two-movement four-freedom-degree parallel loading device are connected through four movement branches. The first end of the first movingbranch 2 is connected with the first end of the fixed platform 1, the first end of the second moving branch 3 is connected with the second end of the fixed platform 1, the first end of the third moving branch 4 is connected with the third end of the fixed platform 1, the first end of the fourth moving branch 5 is connected with the fourth end of the fixed platform 1, the second end of the first movingbranch 2 is connected with the first end of theloading platform 6, the second end of the second moving branch 3 is connected with the second end of theloading platform 6, the second end of the third moving branch 4 is connected with the third end of theloading platform 6, the second end of the fourth moving branch 5 is connected with the fourth end of theloading platform 6, and thefirst force sensors 10 are respectively positioned on the first movingbranch 2, the second moving branch 3, the third moving branch 4 and the fourth moving branch 5.

Thefirst motion branch 2 and the third motion branch 4 have the same structure, and as shown in fig. 2, include arevolute pair 8, arevolute pair 9 and afirst ball pair 11, a first end of therevolute pair 8 is connected to the fixed platform 1, a second end of therevolute pair 8 is connected to a first end of therevolute pair 9, a second end of therevolute pair 9 is connected to a first end of thefirst ball pair 11, and a second end of thefirst ball pair 11 is connected to theloading platform 6. Thefirst force sensor 10 is located between the slidingpair 9 and thefirst ball pair 11.

The second motion branch 3 and the fourth motion branch 5 have the same structure and respectively comprise aU pair 12, a movingpair 13 and asecond ball pair 15, the first end of theU pair 12 is connected with the fixed platform 1, the second end of theU pair 12 is connected with the first end of the movingpair 13, the second end of the movingpair 13 is connected with the first end of thesecond ball pair 15, and the second end of thesecond ball pair 15 is connected with theloading platform 6. Thesecond force sensor 14 is located between the movingpair 13 and the secondspherical pair 15, thefirst force sensor 10 and thesecond force sensor 14 are three-dimensional force sensors, can simultaneously measure forces in three vertical axial directions in a Cartesian coordinate system, and then feed back the forces to an upper computer, so that the magnitude and the direction of wing loading force in the experimental process can be measured.

As shown in fig. 4, each of thefirst ball pair 11 and thesecond ball pair 15 is composed of three revolute pairs with their rotational axes intersecting at a point and perpendicular to each other, namely a firstrevolute pair 16 in the ball pair, a secondrevolute pair 17 in the ball pair, and a thirdrevolute pair 18 in the ball pair.

Therevolute pair 8 of the firstkinematic branch 2, theU pair 12 of the second kinematic branch 3, therevolute pair 8 of the third kinematic branch 4 and theU pair 12 of the fourth kinematic branch 5 are coplanar and parallel to the fixed platform 1, therevolute pair 8 of the firstkinematic branch 2, theU pair 12 of the second kinematic branch 3, therevolute pair 8 of the third kinematic branch 4 and theU pair 12 of the fourth kinematic branch 5 are distributed in a diamond shape, and the rotation axes of therevolute pairs 8 of the firstkinematic branch 2 and the thirdkinematic branch 2 are parallel to each other and perpendicular to the connecting line between the two. The first ball pairs 11 and 15 in the four movement branches are coplanar, the plane formed by the four ball pairs is parallel to theloading platform 6, and the four ball pairs are distributed in a diamond shape. The four ball pairs are distributed in a diamond shape and are coplanar, so that the bearing capacity of the parallel device can be increased, and the calculation is convenient.

The two secondary lever systems 7 are positioned above theloading platform 6 and symmetrically distributed at two ends of the loading platform. The two secondary lever systems are symmetrically distributed, and theprimary lever beam 19 is structurally shown in fig. 6, and the rotation axis thereof is parallel to theloading platform 6. The primary lever beam is parallel and collinear with theattachment hole 191 of the loading platform. The connectinghole 191 of the first-level lever beam and the loading platform is parallel and coplanar with the connecting line of thefirst ball pair 11 of the first movingbranch 2 and the third moving branch 3. The second-level lever beams 20 are symmetrically distributed, the rotation axes of the second connectingholes 201 are perpendicular to the connectingholes 191 of the first-level lever beams and the loading platform, and the first connectingholes 192 are coaxially connected with the second connectingholes 201. Thesecond shaft hole 202 is a shaft hole of theloading panel 21 connected with the secondary lever, and is parallel to the axis of the second connectinghole 201.

The parallel mechanism in the wing static strength experiment loading device based on the parallel mechanism and the lever system has two degrees of freedom of rotation and two movements, and can apply loading force in any direction to thewing 22. The loading device is fixedly connected with the lower surface of thewing 22 through a loading panel in a lever system, as shown in fig. 8. During loading, the direction of the required loading force changes due to large deformations of thewing 22, which requires adjustment of the orientation of theloading platform 6.

The use method of the loading device comprises the following steps:

s1, theoretically analyzing thewings 22, determining required loading point positions, calculating the theoretical loading force of each loading point position in the loading experiment process, and calculating the resultant force of the theoretical loading forces of each group of loading point positions in the experiment process, wherein each group of loading point positions has eight loading points, and the resultant force of the loading forces of each eight loading point positions is the loading force required to be applied by the loading platform. Predicting the deformation condition of thewing 22 through theoretical calculation, determining the displacement required by a loading device, and planning the motion path of the movable platform in an actual loading experiment;

s2, starting loading, keeping the path in the first step, driving theloading platform 6 to move, detecting the magnitude and direction of the reaction force of theairplane wing 22 on theloading platform 6 in real time through theforce sensors 10 and 14 in the moving branch, and detecting the deformation condition of thewing 22 in real time in the experimental process;

s3, judging the loading force of thewing 22 after detecting the deformation condition of thewing 22, calculating the angle difference between the loading force and the surface of thewing 22, and calculating the angle to be adjusted according to the detected deformation condition of thewing 22 and the pose of the wingexperiment loading device 23 when the loading force is not vertical to the surface of thewing 22 in the experiment;

s4, after the angle required to be adjusted is calculated, the displacement required by the sliding pair in each moving branch can be calculated through inverse kinematics solution, and the adjustment of the direction of the loading force is completed;

and S5, after the operation of the fourth step is completed, if the loading force of the wing loading device still has an error with the surface normal direction of thewing 22, repeating the steps 3 and 4 until the precision requirement is met.

The loading device and the adjusting method for the wing static strength experiment based on the parallel mechanism and the lever system are further described by combining the embodiment as follows:

the first embodiment is as follows:

a plurality of wing static strengthexperiment loading devices 23 based on a parallel mechanism and a lever system are selected to carry out related static experiment loading on theairplane wing 22, and theloading platform 6 has four degrees of freedom which are two translation degrees of freedom and two rotation degrees of freedom respectively.

S1, theoretically analyzing theairplane wing 22, presetting the force theoretically needed to be loaded and the pose needed to be reached by the static forceexperiment loading device 23 of the wing, measuring the stress state on the corresponding branch through thefirst force sensor 10 arranged on the branch, and after detecting the stress state on the branch, performing force conversion equation

Calculating the magnitude and direction of the counterforce of theloading platform 6 on theairplane wing 22, wherein F is the counterforce of the wing on the loading device,

in order to load the weight of theplatform 6 and the secondary lever system 7,

measuring a force vector for the force sensor in the ith branch;

s2, applying a load on the wing static forceexperiment loading device 23 to enable the deflection of a contact point between theaircraft wing 22 and the wing static strengthexperiment loading device 23 based on the parallel mechanism and the lever system to reach 3m, wherein the contact point simultaneously generates displacement along the wingspan direction of theaircraft wing 22 because theaircraft wing 22 is in a large deformation state at the moment, the displacement is set to 1m, namely the point generates movement in two directions in a plane, and the normal vector of the surface of theaircraft wing 22 at the point is simultaneously changed, so that the actual deformation of theaircraft wing 22 can be determined through the position and posture of theloading platform 6 of the wing static forceexperiment loading device 23;

s3, when the loading force is not perpendicular to the surface of theairplane wing 22 in the test, calculating the angle difference between the loading force applied by the static forceexperiment loading device 23 of the wing and the perpendicular direction of the surface of the airplane wing to be 2 degrees according to the deformation condition of theairplane wing 22 obtained in the step S3, and calculating the rotation of theloading platform 6 by 2 degrees according to the angle difference;

s4, after the motion trail of theloading platform 6 is planned, determining a second motion branch 3 and a fourth motion branch 5 in a plurality of motion branches forming theloading device 23 of the wing static force experiment through inverse kinematics solution of theloading device 23 of the wing static force experiment, and enabling theloading platform 6 to rotate in two directions to adjust the angle of theloading platform 6 by the simultaneous action of two identical branches under the driving action, so as to finish the adjustment of the direction of the loading force;

s5, after the adjustment of the step S4 is completed, if the loading direction of theloading platform 6 in the static forceexperiment loading device 23 has an error, the steps S2 to S4 are repeated until the loading direction of theloading platform 6 in the static forceexperiment loading device 23 reaches the error allowable range.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. As a result of the observation: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

Claims (5)

Translated fromChinese

1.一种飞机机翼静强度实验的加载方法，其特征在于，其包括以下步骤：1. the loading method of an aircraft wing static strength experiment, is characterized in that, it comprises the following steps:S1、对机翼进行理论分析，确定好需要的加载点位，计算出每个加载点位在加载实验过程中的理论加载力，计算出每组加载点位在实验过程中的理论加载力的合力，每组加载点位共有八个加载点，每八个加载点位的加载力的合力为加载平台需要施加的加载力；通过理论计算预估机翼的变形情况，确定加载装置需要的位移，规划好实际加载实验中动平台的运动路径；S1. Perform theoretical analysis on the wing, determine the required loading points, calculate the theoretical loading force of each loading point during the loading experiment, and calculate the theoretical loading force of each group of loading points during the experiment. The resultant force, there are eight loading points in each group of loading points, and the resultant force of the loading forces of each eight loading points is the loading force that needs to be applied by the loading platform; the deformation of the wing is estimated by theoretical calculation, and the displacement required by the loading device is determined. , and plan the motion path of the moving platform in the actual loading experiment;S2、开始加载，安照步骤S1中的路径，驱动动平台运动，通过运动分支中的力传感器，实时检测飞机机翼对加载平台的反作用力的大小与方向，实验过程中实时检测机翼变形情况；S2. Start loading, follow the path in step S1, drive the moving platform to move, and detect the magnitude and direction of the reaction force of the aircraft wing on the loading platform in real time through the force sensor in the motion branch, and detect the deformation of the wing in real time during the experiment. Happening;S3、检测出机翼变形情况后便能对机翼的加载力进行判断，计算出加载力与机翼表面的角度差，当实验中加载力与机翼表面不垂直时，根据所测得机翼的变形情况以及机翼实验加载装置的位姿便能计算出需要调整的角度；S3. After the deformation of the wing is detected, the loading force of the wing can be judged, and the angle difference between the loading force and the surface of the wing can be calculated. When the loading force is not perpendicular to the surface of the wing in the experiment, according to the measured The deformation of the wing and the pose of the wing experimental loading device can calculate the angle that needs to be adjusted;S4、计算出需要调整的角度，通过运动学反解计算每个作动筒需要的位移，完成加载力方向的调整；S4. Calculate the angle that needs to be adjusted, calculate the required displacement of each actuator through the inverse kinematics solution, and complete the adjustment of the loading force direction;S5、完成步骤S4的操作后，若机翼加载装置的加载力与机翼的表面法向仍有误差，则重复步骤S3与步骤S4、直到满足精度要求。S5. After the operation of step S4 is completed, if there is still an error between the loading force of the wing loading device and the surface normal of the wing, step S3 and step S4 are repeated until the accuracy requirements are met.2.一种根据权利要求1所述的飞机机翼静强度实验的加载方法的加载装置，其包括并联加载装置与二级杠杆系统，其特征在于，2. A loading device for the loading method of the aircraft wing static strength experiment according to claim 1, comprising a parallel loading device and a secondary lever system, characterized in that,所述并联加载装置为两转两移的四自由度机构，并联加载装置包括包括定平台、加载平台、力传感器、第一运动分支、第二运动分支、第三运动分支和第四运动分支；The parallel loading device is a four-degree-of-freedom mechanism with two rotations and two shifts, and the parallel loading device includes a fixed platform, a loading platform, a force sensor, a first movement branch, a second movement branch, a third movement branch and a fourth movement branch;所述定平台与动平台通过四个运动分支连接；所述第一运动分支的第一端和所述定平台的第一端连接，所述第二运动分支的第一端和所述定平台的第二端连接，所述第三运动分支的第一端和所述定平台的第三端连接，所述第四运动分支的第一端和所述定平台的第四端连接，所述第一运动分支的第二端和所述加载平台的第一端连接，所述第二运动分支的第二端和所述加载平台的第二端连接，所述第三运动分支的第二端和所述加载平台的第三端连接，所述第四运动分支的第二端和所述加载平台的第四端连接，所述力传感器分别位于所述第一运动分支、所述第二运动分支、所述第三运动分支与所述第四运动分支上；The fixed platform and the moving platform are connected through four moving branches; the first end of the first moving branch is connected with the first end of the fixed platform, and the first end of the second moving branch is connected with the fixed platform The second end of the third movement branch is connected with the third end of the fixed platform, the first end of the fourth movement branch is connected with the fourth end of the fixed platform, and the The second end of the first movement branch is connected to the first end of the loading platform, the second end of the second movement branch is connected to the second end of the loading platform, and the second end of the third movement branch is connected is connected with the third end of the loading platform, the second end of the fourth motion branch is connected with the fourth end of the loading platform, and the force sensor is located at the first motion branch and the second motion branch, respectively. on the branch, the third movement branch and the fourth movement branch;两个二级杠杆系统位于加载平台上方且对称分布在加载平台两端，第一级杠杆系统的旋转轴线平行共线，第一级杠杆系统的旋转轴线与第一运动分支、第三运动分支的球副连接线平行共面，第二级杠杆程对称分布，旋转轴线垂直于一级杠杆的旋转轴线。The two secondary lever systems are located above the loading platform and are symmetrically distributed at both ends of the loading platform. The connecting line of the ball pair is parallel and coplanar, the second-level lever is symmetrically distributed, and the rotation axis is perpendicular to the rotation axis of the first-level lever.3.根据权利要求2所述的加载装置，其特征在于，所述第一运动分支与所述第三运动分支结构相同，所述第二运动分支与所述第四运动分支结构相同且均包括转动副、移动副和球副，所述转动副的第一端与所述定平台连接，所述转动副的第二端与所述移动副的第一端连接，所述移动副的第二端与所述球副的第一端连接，所述球副的第二端与加载平台连接；所述力传感器位于所述移动副与球副之间。3 . The loading device according to claim 2 , wherein the structure of the first movement branch is the same as that of the third movement branch, and the structure of the second movement branch and the fourth movement branch is the same and both include A rotating pair, a moving pair and a ball pair, the first end of the rotating pair is connected with the fixed platform, the second end of the rotating pair is connected with the first end of the moving pair, the second end of the moving pair is connected The end is connected with the first end of the ball pair, and the second end of the ball pair is connected with the loading platform; the force sensor is located between the moving pair and the ball pair.4.根据权利要求2所述的加载装置，其特征在于，所述第二运动分支与所述第四运动分支结构相同，所述第二运动分支与所述第四运动分支结构相同且均包括U副、移动副和球副，所述U副的第一端与所述定平台连接，所述U副的第二端与所述移动副的第一端连接，所述移动副的第二端与所述球副的第一端连接，所述球副的第二端与加载平台连接；所述力传感器位于所述移动副与球副之间。4 . The loading device according to claim 2 , wherein the second movement branch has the same structure as the fourth movement branch, and the second movement branch and the fourth movement branch have the same structure and both include U pair, moving pair and ball pair, the first end of the U pair is connected to the fixed platform, the second end of the U pair is connected to the first end of the moving pair, the second end of the moving pair is connected The end is connected with the first end of the ball pair, and the second end of the ball pair is connected with the loading platform; the force sensor is located between the moving pair and the ball pair.5.根据权利要求4所述的加载装置，其特征在于，所述第一运动分支的转动副、所述第二运动分支的U副、所述第一运动分支的转动副和所述第二运动分支的U副共面，且平行于定平台，所述第一运动分支的转动副、所述第二运动分支的U副、所述第一运动分支的转动副、所述第二运动分支的U副呈菱形分布，所述第一运动分支与所述第三运动分支的转动副的旋转轴线相互平行，且垂直于两者之间的连线；所述四个运动分支中的球副共面，四个球副组成的平面平行于加载平台，所述四个球副呈菱形分布。5. The loading device according to claim 4, wherein the rotation pair of the first movement branch, the U pair of the second movement branch, the rotation pair of the first movement branch and the second movement branch The U pair of the motion branch is coplanar and parallel to the fixed platform, the rotation pair of the first motion branch, the U pair of the second motion branch, the rotation pair of the first motion branch, and the second motion branch The U pairs are distributed in a rhombus shape, and the rotation axes of the rotating pairs of the first motion branch and the third motion branch are parallel to each other and perpendicular to the line between the two; the ball pairs in the four motion branches Coplanar, the plane composed of four ball pairs is parallel to the loading platform, and the four ball pairs are distributed in a diamond shape.

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