Helicopter propeller hub six-component measuring method, system and device

Abstract

The invention provides a helicopter propeller hub six-component measuring device, and the device comprises a ground combined test bench, the lower end surface of which is fixed on a ground rail through a foundation bolt; the frame-type balance is installed on the upper end face of the ground combined test bench, the frame-type balance is a measuring component of six-component force of the helicopter propeller hub, mechanical decomposition of the measured force and torque is thorough, and the interference variable is small; one end of the transition connecting piece is fixedly connected with the frame type balance, and the other end of the transition connecting piece is connected with a helicopter interface; meanwhile, the invention further provides a helicopter propeller hub six-component measuring method and system.

Description

Technical Field

[0001] This application belongs to the technical field of ground joint test in ground comprehensive test, and specifically relates to a method, system and device for measuring six-component forces of a helicopter hub. Background Art

[0002] Before the first flight of a helicopter model or scientific research flight test, it is necessary to first complete a ground joint test. The purpose is to combine the three major moving components (rotor system, transmission system, power system) of the helicopter system together for coordination, functionality, matching and durability test verification. To ensure the safety of the test, it is necessary to comprehensively test and analyze data of different parameters of multiple parts of the helicopter such as fuselage vibration, hub load, and power cabin temperature during the test process, so as to provide complete and effective test data for the analysis of test verification results. Among them, the magnitude of the hub load test parameters is closely related to the flight state and attitude adjustment of the helicopter, and directly affects the flight safety of the helicopter. Therefore, an efficient and accurate method, system and device for measuring hub load are powerful guarantees for carrying out the ground joint test of the helicopter.

[0003] There are mainly two existing methods and devices for measuring hub load. One is to transmit the rotor load signal through a slip ring acquisition device and then measure it through a sensor; however, this method has problems such as the influence of the number and life of slip ring channels, long-distance signal transmission and poor anti-interference ability. The other is to connect the main rotor telemetry device with strain gauges to complete the acquisition of the rotor blade load signal and send it to the signal receiver for measurement in a wireless transmission manner, but the main rotor telemetry device used in this method cannot be used universally on the hubs of different civilian helicopter models and needs to be customized according to the size and structure of each model's hub. Moreover, the telemetry device is usually installed at the top of the helicopter hub, and the regular charging and maintenance of the device are inconvenient.

[0004] Therefore, a hub load measurement method, system and device that are universal for measuring hub loads of multiple helicopter models, convenient for maintenance, and efficient and accurate can effectively guarantee the safety of the ground joint test. Summary of the Invention

[0005] Object of the Invention: The main technical problem to be solved by the present invention is to provide an efficient and accurate method, system and device for measuring hub load, which can realize on-line real-time monitoring and data analysis of rotor hub load.

[0006] In a first aspect, the present application provides a device for measuring six-component forces of a helicopter hub, and the measuring device includes:

[0007] A ground joint test bench, the lower end surface of the ground joint test bench is fixed on the ground rail through anchor bolts;

[0008] A frame balance, installed on the upper end face of the ground combined test bench, the frame balance is a measuring component for the six-component forces of the helicopter hub, and the mechanical decomposition of the measured forces and moments is relatively thorough with small interference quantities;

[0009] A transition connecting piece, one end of the transition connecting piece is fixedly connected to the frame balance, and the other end of the transition connecting piece is connected to the helicopter interface.

[0010] Preferably, the ground combined test bench is designed as a split-type ground combined test bench according to the structural dimensions of the helicopter.

[0011] Preferably, the ground combined test bench includes:

[0012] The nose landing gear bench;

[0013] The left and right main landing gear benches, and the distribution areas of the nose landing gear bench and the left and right main landing gear benches can ensure that the main load-bearing frames of the fuselage are within this range.

[0014] Preferably, the frame balance includes:

[0015] A fixed frame, connected to the upper end face of the ground combined test bench;

[0016] A floating frame, connected to the transition connecting piece;

[0017] An elastic connecting rod, one end of the elastic connecting rod is connected to the fixed frame, and the other end of the elastic connecting rod is connected to the floating frame.

[0018] In a second aspect, the present application also provides a helicopter hub six-component force measurement system, the measurement system includes a signal acquisition and processing system, and the signal acquisition and processing system includes:

[0019] A strain gauge, arranged on the elastic connecting rod;

[0020] A measurement circuit, namely a Wheatstone bridge, the measurement circuit is arranged on the elastic connecting rod;

[0021] Wherein, the strain gauge will generate deformation under the action of the load, causing its resistance value to change, and this resistance value change amount is proportional to the applied load value, and the resistance change is manifested as a change in voltage after passing through the Wheatstone bridge.

[0022] Preferably, the signal acquisition and processing system further includes an amplifier, a filter, an analog-to-digital converter and a computer;

[0023] Wherein, the amplifier amplifies the voltage signal, and after passing through the filter and the analog-to-digital converter, it is input to the computer for processing to obtain the load received by the frame balance.

[0024] Preferably, the signal acquisition and processing system further includes a regulated power supply and a data recording and display device.

[0025] In a third aspect, the present application also provides a method for measuring six-component forces of a helicopter hub. The measurement method includes:

[0026] Take the helicopter coordinate system O(x, y, z); where x represents the heading direction, y represents the longitudinal direction, and z represents the vertical lift direction.

[0027] Take the central force application points of the frame balance as F1(x1, y1, z1), F2(x2, y2, z2), and F3(x3, y3, z3) respectively.

[0028] Take the central force application point of the helicopter hub as F J (x J , y J , z J ), and take the projection point of the central force application point F J on the plane where F1, F2, and F3 are located as F J ’(x J ’, y J ’, z J ’). F J ’ and F1, F2, F3 satisfy the following relationships:

[0029] F J ’x = F1x + F2x + F3x (1)

[0030] F J ’y = F1y + F2y + F3y (2)

[0031] F J ’z = F1z + F2z + F3z (3)

[0032] M J ’x = (F2 - F3) × l3 (4)

[0033] M J ’y = (F2 + F3) × l1 - F1 × l2 (5)

[0034] M J ’z = (F2 + F3) × l1 - F1 × l2 (6)

[0035] F J ’ and F J in the spatial coordinate system, to obtain that F J ’ and F J satisfy the following relationships:

[0036] F J x = F J ’x (7)

[0037] F J y = F J ’y (8)

[0038] F J z = F J ’z (9)

[0039] M J x = -F J ’y × l4 (10)

[0040] M J y = F J ’x × l4 (11)

[0041] M J z = M J ’z (12)

[0042] Substituting formulas (1)-(6) into formulas (7)-(12) gives:

[0043] F J x = F1x + F2x + F3x (13)

[0044] F J y = F1y + F2y + F3y (14)

[0045] F J z = F1z + F2z + F3z (15)

[0046] M J x = -(F1y + F2y + F3y)×l4 (16)

[0047] M J y = (F1x + F2x + F3x) × l4 (17)

[0048] M J z = (F2 + F3)×l1 - F1×l2 (18)

[0049] Therefore, after converting the six-component force signals measured by the frame balance, the six-component force at the hub center is obtained.

[0050] The present application has the following technical effects:

[0051] The present invention adopts a modular test bench design. The test bench can be flexibly designed according to the configuration and structure of the helicopter, which is simple and practical and has universality in the hub load tests of various types of civil helicopters. A frame balance is used as the measuring element, which has high stiffness and little interference and can effectively and accurately measure load data. The present invention is applied to ground joint tests to meet the requirements of on-line real-time monitoring, is convenient to use and maintain, and ensures the normal operation of the helicopter. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a composition diagram of the signal acquisition and processing system provided by an embodiment of the present application;

[0053] Figure 2 is the schematic diagram of the positional relationship of F J ’ and F1, F2, F3 in the same plane provided by an embodiment of the present application;

[0054] Figure 3 is the schematic diagram of the positional relationship of F J ’ and F J in the same plane provided by an embodiment of the present application;

[0055] Figure 4 is the schematic diagram of the main test bench structure provided by an embodiment of the present application;

[0056] Figure 5 is the schematic diagram of the frame balance structure provided by an embodiment of the present application;

[0057] Figure 6 is the schematic diagram of the ground joint test bench structure provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0058] Please refer to Figures 1 - 6 , the present invention designs a method, system and device for measuring six-component forces of a helicopter hub. The implementation of this measurement method relies on corresponding measurement devices. The measurement devices designed in the present invention mainly include three parts: a ground joint test bench, a frame balance and a transition connector.

[0059] Among them, the ground joint test bench is designed into a split structure according to the structural size characteristics of the helicopter, including a front landing gear test bench and left and right rear landing gear test benches, which play a supporting role for the test machine and at the same time provide a platform for the installation of various sensors, test equipment and circuits; the frame balance is a measuring component for the six-component forces of the helicopter hub, and the mechanical decomposition of the measured forces and torques is relatively thorough with little interference; the transition connector plays a role in connecting the test machine and the test bench. The present invention has universality in the hub load tests of various types of helicopters, is convenient for maintenance, and the measured test data has little interference and small error, which can effectively ensure the safety of ground joint tests.

[0060] The technical solution adopted by the present invention to solve its technical problems mainly includes the following steps:

[0061] 4.1. Design of the measuring device

[0062] The measuring device adopted by the present invention mainly includes a split-type ground combined test bench, a frame balance, and a transition connector. The schematic diagram is as Figure 4 shown.

[0063] 1. Ground combined test bench

[0064] The ground combined test bench is designed as a split-type ground combined test bench according to the structural dimensions of the helicopter, including a front landing gear bench 1 and left and right main landing gear benches 2, which are made of steel and meet the maximum load requirements during ground combined tests; the distribution areas of the front landing gear bench 1 and the left and right main landing gear benches 2 ensure that the main load-bearing frames of the fuselage are within this range. The lower end surface of the split-type ground combined test bench is fixed to the ground rail through anchor bolts, and the frame balance 3 is installed on the upper end surface.

[0065] 2. Frame balance

[0066] The frame balance 3 is composed of a floating frame 31, a fixed frame 32, and elastic connecting rods 33 (as Figure 5 shown), the fixed frame 32 is connected to the split-type ground combined test bench frame, the floating frame 31 is connected to the transition connector 4, and the fixed frame 32 and the floating frame 31 are connected by elastic connecting rods 33. The frame balance 3 is made of steel, has a large stiffness, and with the lateral degrees of freedom of the additional elastic connecting rods 33, a more thorough mechanical decomposition of forces and moments can be achieved, and the interference amount is small.

[0067] 3. Transition connector

[0068] The transition connector 4 needs to be designed separately according to the structure and dimensions of the helicopter connection interface, and the material selection needs to be determined in combination with the relevant requirements of the helicopter connection interface. One end is fixed to the floating frame 31 of the frame balance 3, and the other end is connected to the helicopter interface to fix the helicopter on the test bench for ground combined tests.

[0069] The schematic diagram of the overall ground combined test bench is as Figure 6 shown.

[0070] 4.2. Design of the measuring system and method

[0071] 1. Measuring system

[0072] During the ground joint test, the rotor blades will adjust their corresponding postures according to the input control instructions. Due to factors such as air resistance, self-gravity, and mechanical operation, forces and torques will be generated on the rotor blades in the flapping direction, lead-lag direction, and torsional direction. These forces and torques are conducted to the hub through the blades, that is, hub loads are formed. The hub loads can be directly transmitted to the floating frame 31 of the frame balance 3 through the fuselage. After the floating frame 31 is subjected to the load, it will generate corresponding movements in a certain direction (such as stretching and torsion). One end of the elastic link 33 is connected to the movable floating frame 31, and the other end is connected to the immovable fixed frame 32. Therefore, the elastic link 33 will be deformed under the action of the load (such as stretching and torsion). By arranging strain gauges and measurement circuits (Wheatstone bridge) on the elastic link 33, the strain gauges will be deformed under the action of the load, causing a change in their resistance values. This change in resistance value is proportional to the applied load value. The change in resistance is manifested as a change in voltage after passing through the Wheatstone bridge. After amplifying the voltage signal and performing A / D conversion, it is input to a computer for processing, and the load received by the balance can be obtained. Therefore, during the test, by monitoring the load received by the balance, the hub load value can be obtained through coordinate conversion.

[0073] The signal acquisition and processing system consists of a regulated power supply, a frame balance, an amplifier, a filter, an analog-to-digital converter (A / D), a data recording and display device, and a computer, etc. The flow schematic diagram is as Figure 1 shown.

[0074] 2. Measurement method

[0075] As Figure 6 shown, take the helicopter coordinate system O(x, y, z), where x represents the heading direction, y represents the longitudinal direction, and z represents the vertical lift direction. Take the central force points of the frame balance [3] on the ground joint test bench as F1(x1, y1, z1), F2(x2, y2, z2), F3(x3, y3, z3) respectively, and take the central force point of the helicopter hub as F J (x J , y J , z J ). Take the projection point of the central force point F J of the hub on the plane where F1, F2, and F3 are located as F J ’(x J ’, y J ’, z J ’). Then the positional relationship between F J ’ and F1, F2, F3 in the same plane is as Figure 2 shown. From this, it can be obtained that the relationship between F J ’ and F1, F2, F3 is as follows:

[0076] F J’x = F1x + F2x + F3x (1)

[0077] F J ’y = F1y + F2y + F3y (2)

[0078] F J ’z = F1z + F2z + F3z (3)

[0079] M J ’x = (F2 - F3)×l3 (4)

[0080] M J ’y = (F2 + F3)×l1 - F1×l2 (5)

[0081] M J ’z = (F2 + F3)×l1 - F1×l2 (6)

[0082] F J ’ and F J in the spatial coordinate system is as Figure 3 shown, from which we can obtain F J ’ and F J satisfy the following relationship (the positive and negative signs are determined by the right - hand screw rule):

[0083] F J x = F J ’x (7)

[0084] F J y = F J ’y (8)

[0085] F J z = F J ’z (9)

[0086] M J x = -F J ’y ×l4 (10)

[0087] M J y = F J ’x ×l4 (11)

[0088] M J z = M J ’z (12)

[0089] Substituting formulas (1) - (6) into formulas (7) - (12) gives:

[0090] F Jx = F1x + F2x + F3x (13)

[0091] F J y = F1y + F2y + F3y (14)

[0092] F J z = F1z + F2z + F3z (15)

[0093] M J x = -(F1y + F2y + F3y)×l4 (16)

[0094] M J y = (F1x + F2x + F3x) ×l4 (17)

[0095] M J z = (F2 + F3)×l1 - F1×l2 (18)

[0096] Therefore, after converting the six - component force signals measured by the frame balance [3], the magnitudes of the six - component forces at the hub center can be directly obtained.

[0097] The key points of the present invention are as follows:

[0098] 1) The design method of the ground combined test bench of the present invention can be flexibly designed according to the tonnage and structural dimensions of the helicopter, and can be designed into a split - type ground combined test bench or an integral ground combined test bench as needed.

[0099] 2) The present invention uses the frame balance as a part of the ground combined test bench, which can serve as a support and a connecting part, and at the same time, as a force - measuring element, it can realize the decomposition of forces and torques, with high measurement accuracy, meet the on - line real - time monitoring, and is convenient to use and maintain.

[0100] The present invention adopts a modular test bench design. The test bench can be flexibly designed according to the configuration and structure of the helicopter, is simple and practical, and has universality in the hub load tests of various types of civil helicopters; it uses the frame balance as a measuring element, which has a large stiffness, little interference, and can effectively and accurately measure load data; the present invention is applied to the ground combined test to meet the on - line real - time monitoring requirements, is convenient to use and maintain, and ensures the normal operation of the helicopter.

Claims

1. A six-component force measuring device for a helicopter hub, characterized in that The measurement device includes: A ground combined test bench, the lower end face of which is fixed on the ground rail by anchor bolts; A frame balance, installed on the upper end face of the ground combined test bench. The frame balance is a measuring component for the six-component forces of the helicopter hub. The mechanical decomposition of the measured forces and torques is relatively thorough, and the interference is small; A transition connecting piece, one end of which is fixedly connected to the frame balance, and the other end of which is connected to the helicopter interface.

2. The measuring device according to claim 1, characterized in that, The ground combined test bench is designed as a split ground combined test bench according to the structural dimensions of the helicopter.

3. The measuring device according to claim 1, characterized in that, The ground combined test bench includes: The nose landing gear bench; The left and right main landing gear benches. The distribution areas of the nose landing gear bench and the left and right main landing gear benches can ensure that the main load-bearing frames of the fuselage are within this range.

4. The measuring device according to claim 1, characterized in that, The frame balance includes: A fixed frame, connected to the upper end face of the ground combined test bench; A floating frame, connected to the transition connecting piece; Elastic connecting rods, one end of each elastic connecting rod is connected to the fixed frame, and the other end is connected to the floating frame.

5. A six-component force measurement system for a helicopter hub, characterized in that, The measurement system includes a signal acquisition and processing system, and the signal acquisition and processing system includes: Strain gauges, arranged on the elastic connecting rods; A measurement circuit, namely a Wheatstone bridge, arranged on the elastic connecting rods; Among them, the strain gauges will deform under the action of the load, causing their resistance values to change. This change in resistance value is proportional to the applied load value. After passing through the Wheatstone bridge, the resistance change is manifested as a change in voltage.

6. The measurement system according to claim 5, characterized in that, The signal acquisition and processing system also includes an amplifier, a filter, an analog-to-digital converter, and a computer; Among them, the amplifier amplifies the voltage signal. After passing through the filter and the analog-to-digital converter, it is input into the computer for processing to obtain the load received by the frame balance.

7. The measurement system according to claim 6, characterized in that, The signal acquisition and processing system also includes a regulated power supply, a data recording and display device.

8. A method for measuring six-component forces of a helicopter hub, characterized in that, The measurement method includes: Taking the helicopter coordinate system O(x, y, z); where x represents the heading direction, y represents the longitudinal direction, and z represents the vertical lift direction; Taking the central force application points of the frame balance as F1(x1, y1, z1), F2(x2, y2, z2), F3(x3, y3, z3) respectively; Take the center force point of the helicopter hub as F J (x J 、y J 、z J ), take the force point F at the hub center J The projection point on the plane where F1, F2, and F3 are located is F J '(x J '、y J '、z J '),F J 'The relationship with F1, F2, and F3 is as follows: F J ’x = F1x + F2x + F3x (1) F J ’y = F1y + F2y + F3y (2) F J ’z = F1z + F2z + F3z (3) M J ’x = (F2 - F3)×l3 (4) M J ’y = (F2 + F3)×l1 - F1×l2 (5) M J ’z = (F2 + F3)×l1 - F1×l2 (6) F J ’s positional relationship with F J in the spatial coordinate system gives F J ’s relationship with F J satisfies the following relationship: F J x = F J ’x (7) F J y = F J ’y(8) F J z = F J ’z(9) M J x = -F J ’y × l4 (10) M J y = F J ’x × l4 (11) M J z = M J ’z (12) Substituting formulas (1)-(6) into formulas (7)-(12) gives: F J x = F1x + F2x + F3x (13) F J y = F1y + F2y + F3y (14) F J z = F1z + F2z + F3z (15) M J x = -(F1y + F2y + F3y) × l4 (16) M J y = (F1x + F2x + F3x) × l4 (17) M J z = (F2 + F3)×l1 - F1×l2 (18) Therefore, after converting the six-component force signals measured by the frame balance, the six-component forces at the hub center are obtained.

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