A multi-dimensional force decoupling method based on overall and local displacement of the test system

Abstract

A multi-dimensional force decoupling method based on the overall and local displacement of the test system belongs to the technical field of multi-dimensional force testing of engines. In view of the influence of force displacement on the test process in the engine thrust test system, a certain multi-dimensional composite force is first generated by a combined force generating device. The force measuring components at different positions will produce different displacements under the action of the force. The displacement of the position of the sensor in each component is obtained by measuring, and the deflection coordinate system of the sensor axis is obtained. At the same time, the three-dimensional displacement components of the movable frame and the engine as a whole are measured, and the overall coordinate system of the movable frame is established. The angular deflection between the movable frame coordinate system and the sensor coordinate system in the force measuring assembly is calculated, and the three-directional force components in the movable frame coordinate system are obtained in combination with the actual output force value of the sensor. Then, the data is decoupled and restored through the partial relationship between the movable frame coordinate system and the global coordinate system. The present invention traces the cause of the coupling, can simplify the calculation process, and improve the decoupling accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine multi-dimensional force testing, and relates to a multi-dimensional force decoupling method based on the overall and local displacements of a testing system, which can achieve the decoupling of the output of the testing system when the engine and the dynamic frame generate spatial displacements when multi-dimensional forces act simultaneously, and effectively improve the accuracy of multi-dimensional force testing. Background Art

[0002] As the size and thrust of aircraft engines continue to increase, most of the multi-dimensional thrust measurements of engines are carried out using a spatially distributed test bench. The engine is fixedly connected to the dynamic frame, and 6 measuring points are arranged around the dynamic frame of the engine. Each measuring point is arranged with a force measuring component, and a force sensor is connected in series in the component. The main stiffness of the force measuring component is much greater than the lateral stiffness to reduce the load on the sensor. The six force measuring components restrict the six degrees of freedom of the dynamic frame. By calculating the output values ​​of the six sensors, the multi-dimensional thrust parameters generated by the engine can be obtained.

[0003] During the thrust measurement process, due to the weak lateral stiffness of the force measuring assembly and the asymmetric position of the force measuring assembly, during the test, especially when multi-dimensional forces act simultaneously, the force measuring assembly will be displaced, and the positions of the engine and the dynamic frame will change. This will cause the engine force transmission line to change, the sensor output direction to deviate from the ideal direction, and cause coupling between multi-dimensional forces.

[0004] The current decoupling methods include linear decoupling and nonlinear decoupling. Linear decoupling decouples multi-directional loading by establishing a unidirectional interference matrix, integrating the matrix, and nonlinear decoupling can also achieve the decoupling effect by training the experimental data through methods such as deep learning. The existing decoupling methods all start from the data and do not trace the cause of the coupling. This method may be effective for the overall data, but it lacks data restoration for the output of each single force measuring component and the monitoring of the local state of the test system. For this reason, there is an urgent need for a decoupling method under the synergistic action of multi-dimensional forces that can simultaneously consider the position changes of the engine and the frame and the displacement of the force measuring component, and decouple in principle. Summary of the invention

[0005] In order to overcome the defects of the prior art, the present invention provides a multi-dimensional force decoupling method based on the overall and local displacements of the test system. First, a multi-dimensional composite force is applied to the tail of the test system, and a local coordinate system is established by measuring the displacement of the tail end of the component and the sensor part, and the relationship between the local coordinate systems and the local coordinate system and the global coordinate system is calculated. The input force is decoupled by combining the force balance equation and the output of the sensors at each point.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A multi-dimensional force decoupling method based on the overall and local displacement of a test system is implemented based on the test system. The test system includes five parts: an engine model, a dynamic frame, a force measuring assembly, a fixed frame, and a resultant force generating device. First, a resultant force is applied to the test system, and a displacement measuring device is arranged around the force measuring assembly and the dynamic frame. The three-dimensional displacement of the connecting parts on both sides of the unidirectional force sensor under the force of the six force measuring assemblies is measured respectively, and the local coordinate system of each sensor is established at the center of each unidirectional force sensor; at the same time, the overall three-dimensional displacement components of the dynamic frame and the engine under test are measured to establish the overall coordinate system of the dynamic frame; secondly, the angular deflection between the local coordinate system of the dynamic frame and the overall coordinate system of the dynamic frame in the force measuring assembly is calculated, and the three-directional force components of the sensor position in the overall coordinate system of the dynamic frame are calculated in combination with the sensor force measuring direction, and then the input multi-dimensional force can be decoupled through the deflection between the overall coordinate system of the dynamic frame and the global coordinate system.

[0008] The specific steps are as follows:

[0009] Step 1: Displacement measurement of the test system under the combined force

[0010] The test system mainly includes five parts: an engine model, a dynamic frame, a plurality of force measuring components, a fixed frame, and a resultant force generating device. The fixed frame is fixed. The engine model is the object to be tested and is fixedly connected to the dynamic frame without displacement. The dynamic frame is an engine support structure, the inner side of which is fixed to the engine and the outer side is connected to the force measuring components. The force measuring components are arranged between the dynamic frame and the fixed frame according to a certain rule. Each force measuring component contains a unidirectional force sensor in the middle to measure the external force applied to the engine. A resultant force generating device is arranged at one end of the test system to generate a standard resultant force, which can be decomposed into three directional components. Furthermore, there are six force measuring components, which are respectively arranged in the X, Y, and Z directions of the test system. The engine axial direction is defined as the X direction, the vertical direction as the Z direction, and the horizontal direction as the Y direction as the global coordinate system.

[0011] Displacement measuring devices in two directions are arranged at the connection parts on both sides of the unidirectional force sensor in each force measuring component, and displacement measuring devices are arranged on the three adjacent sides of the dynamic frame. The resultant force is applied to one end of the engine through the resultant force generating device. The step loading method is adopted, and the loading is repeated multiple times. The output data of the unidirectional force sensor in each force measuring component is recorded, and the average value of the multiple experimental data is recorded as F i(i=1,2,3···). Measure the output values ​​of the displacement measuring device at the upper and lower positions of the unidirectional force sensor in each force measuring component and the displacement measuring device on the dynamic frame after each step loading is stabilized. Also take the average value of multiple experimental measurement results, and finally obtain the local three-dimensional displacement of the dynamic frame at the connection parts on both sides of the unidirectional force sensor in the force measuring component. Establish the local coordinate system of the dynamic frame at the center of the unidirectional force sensor. At the same time, measure the overall three-dimensional displacement components of the dynamic frame and the engine under test, and establish the overall coordinate system of the dynamic frame.

[0012] Step 2: Establish a local coordinate system and calculate the offset angle

[0013] According to the measured three-dimensional displacement of the connection structure on both sides of the unidirectional force sensor in the force measuring assembly, the axial coordinate axis deflection vector Zi0 (i=1,2,3···) in the local coordinate system of the sensor is determined, and the axial coordinate axis direction angle after the sensor is deflected is obtained. The displacement measurement data of two endpoints in three directions of the entire movable frame are processed to obtain the vector of each coordinate axis of the overall coordinate system of the movable frame in the global coordinate system. The angle between the coordinate axis of the axial direction of the unidirectional force sensor in the local coordinate system of each force measuring assembly and the overall coordinate system of the movable frame is calculated, and a relationship model between the sensor measurement direction and the three directions of the movable frame is established to provide an angle reference for multi-dimensional force decoupling calculation.

[0014] Step 3: Decoupling of test system output data

[0015] According to the angular relationship between the overall coordinate system of the moving frame and the local coordinate system of the sensors of each force measuring component, the output force value of the unidirectional force sensor in each force measuring component is decomposed according to the overall coordinate system of the moving frame, and the three-directional force components in the overall coordinate system of the moving frame can be obtained. The three-directional output force values ​​in the overall coordinate system of the moving frame can be obtained by adding the three-directional force components of the unidirectional force sensors in each force measuring component in the moving frame coordinate system. Then, the output data can be decoupled through the rotation angle of the three coordinate axes of the moving frame coordinate system in the global coordinate system.

[0016] Beneficial effects of the present invention:

[0017] (1) The present invention aims at the coupling problem caused by the displacement of the engine thrust test system under multi-dimensional forces. By measuring the sensor deflection vector in each force measuring component of the test system under the action of the combined force, the local coordinate system of each sensor after displacement and the overall coordinate system of the movable frame are reestablished, the angular relationship between the axial coordinate axis in each sensor coordinate system and the movable frame coordinate system is obtained, and the three-directional force components in the overall coordinate system of the movable frame are calculated according to the main measurement direction of the sensor. Then, the three-directional force components in the global coordinate system are calculated to achieve high-precision decoupling of the input force.

[0018] (2) This method traces the cause of inter-dimensional coupling and establishes the angular relationship between the local coordinate system of the displacement sensor, the overall coordinate system of the movable frame, and the global coordinate system. It solves the problems of low accuracy, cumbersome and difficult to understand data fitting and solution process in other methods, and improves the test accuracy of the test system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the decoupling method.

[0020] Figure 2 This is a schematic diagram of the thrust test system and the installation location of the force measurement component.

[0021] Figure 3 This is a schematic diagram of the structure of force measuring component No. ① and the local coordinate system.

[0022] In the figure: ①, ②, ③ are the Z-direction force measuring components of the test system; ④, ⑤ are the X-direction components of the test system; ⑥ is the Y-direction force measuring component of the test system; A is the simulated engine model; B is the dynamic frame structure; C is the force generating device; D is the standard force sensor; a is the unidirectional force strain sensor in the force measuring component; l is the displacement length of the front section of the sensor; u ijk are the two lateral displacements at the connection positions on both sides of the sensor in the force measuring assembly; u i is the overall displacement of the movable frame in three directions; OXYZ is the global coordinate system; O'X'Y'Z' is the local coordinate system of the movable frame after displacement due to force; O10X10Y10Z10 is the local coordinate system of the sensor in the force measuring component No. ① after displacement due to force. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings and technical solutions.

[0024] The process of multi-dimensional force decoupling method based on the overall and local displacement of the test system is as follows: Figure 1 As shown, the multi-dimensional force decoupling method is implemented based on a test system and includes the following steps:

[0025] Step 1: Measure the displacement of the local force measuring component and the entire movable frame

[0026] The test system structure is as follows Figure 2As shown, it includes five parts: engine model A, dynamic frame structure B, force measuring assembly (①-⑥), fixed frame, and resultant force generating device C, wherein the fixed frame is fixed, and the engine axial direction is defined as X direction, the vertical direction is defined as Z direction, and the horizontal direction is defined as Y direction. The engine model is the object to be tested, which is fixedly connected to the dynamic frame, and no displacement is generated between the two. The dynamic frame is the engine support structure, the inner side of which is fixed to the engine, and the outer side is connected to the force measuring assembly. There are six force measuring assemblies, which are arranged between the dynamic frame and the fixed frame. Specifically, 2, 1, and 3 force measuring assemblies are placed in the X, Y, and Z directions of the test system, respectively. Each force measuring assembly contains a standard force sensor D in the middle, which is used to measure the external force applied to the engine. A resultant force generating device C is set at one end of the test system to generate a standard resultant force, which can be decomposed into three directional components. Displacement measuring devices in two directions are arranged at the connecting parts on both sides of the unidirectional force sensor in each force measuring assembly, and displacement measuring devices are arranged on the three adjacent sides of the dynamic frame.

[0027] First, a resultant force is applied through the resultant force generating device C, and the force value is controlled by the standard force sensor D in series. The force application point is at the center point of the engine model. When an external force is applied to one end of the engine, the six force measuring components will be subjected to three-dimensional forces of different magnitudes and directions, and produce displacements in three directions. At the same time, due to the local displacement of the force measuring components, the entire dynamic frame also undergoes three-dimensional displacement. Displacement measuring devices are arranged at the connection positions on both sides of the sensor in the force measuring component to obtain the displacement of the unidirectional force sensor. The structure of the force measuring component (taking the force measuring component at position ① as an example) is as follows: Figure 3 As shown in the figure, the middle a is a unidirectional force sensor, and the displacement measurement values ​​on both sides are u 1xa ,u 1ya ,u 1xb ,u 1yb The measurement method of the force measuring components at positions ② and ③ is the same as that of the force measuring components at position ①. To avoid coordinate rotation, the local coordinate axis direction of the force measuring components at other positions is the direction of the global coordinate system. Therefore, for the force measuring components at positions ④ and ⑤, the displacement in the Y and Z directions is measured, and the displacement output is u 4ya ,u 4za ,u 4yb ,u 4zb ,u 5ya ,u 5za ,u 5yb ,u 5zb ; For the ⑥ position force measurement component, the displacement in the X and Z directions needs to be measured, and the displacement output is u 6xa ,u 6za ,u 6xb ,u 6zb .

[0028] Take two endpoints on any three mutually perpendicular sides of the movable frame to measure the displacement of the movable frame, and the measurement result is recorded as u i,v i ,w i (i=1,2).

[0029] Step 2: Establish the local coordinate system of the force measuring component and the overall coordinate system of the movable frame

[0030] According to the measured displacement of each force measuring component, the axial coordinate vector of the force measuring component can be calculated by formula (1).

[0031]

[0032] Similarly, the vectors of the three coordinate axes after the movable frame is displaced can be expressed as:

[0033]

[0034] Then, the angle between the axial coordinate axis of the force measuring component and the three coordinate axes of the movable frame coordinate system can be obtained, and the components of the axial force of the force measuring component on the three coordinate axes of the movable frame can be obtained. The calculation formula is as follows:

[0035]

[0036] The three-axis forces in the movable frame coordinate system are:

[0037]

[0038] Step 3: Decoupling of test system output data

[0039] Formula (4) can be used to decompose the force measured by the sensors of each force measuring component into the movable frame coordinate system. The decoupled output force value can be obtained according to the angle relationship between the movable frame coordinate system and the global coordinate system. The calculation formula is as follows:

[0040]

[0041] The final decoupling force value can be obtained by calculating the above formula, completing the multi-dimensional force decoupling of the test system.

[0042] This method measures the displacement of each force measuring component during the force-bearing process of the test system, establishes the local coordinate system of the sensor position and the overall coordinate system of the movable frame, maps the output force value of the unidirectional force sensor at each measuring point to the movable frame coordinate system through the relationship between the two coordinate systems, and then calculates the output force value by calculating the relationship between the movable frame coordinate system and the global coordinate system to achieve the decoupling function. The cause of the coupling is traced, and the problems of cumbersome calculation, large amount of calculation, and low precision in the current decoupling method are solved, thereby improving the test accuracy.

[0043] Although the present invention is described in detail, it is not limited to the above-mentioned situations. With the understanding of the present invention, those skilled in the art can make changes without departing from the scope of the present invention. The present method can also be used for decoupling in situations such as seven force measuring components, eight force measuring components, or different force measuring component layouts, by simply increasing the number of coordinate systems and their relationships. Therefore, the additions made to the technology and the replacement of some of the same contents in the field should all fall within the scope of the present invention.

Claims

1. A multi-dimensional force decoupling method based on the overall and local displacement of a test system, characterized in that: The multi-dimensional force decoupling method is implemented based on a test system, which includes five parts: an engine model, a dynamic frame, a force measuring assembly, a fixed frame, and a resultant force generating device. First, a resultant force is applied to the test system, and a displacement measuring device is arranged around the force measuring assembly and the dynamic frame to respectively measure the three-dimensional displacement of the connecting parts on both sides of the unidirectional force sensor of the six force measuring assemblies under force, and a local coordinate system of each sensor is established at the center of each unidirectional force sensor. At the same time, the overall three-dimensional displacement components of the dynamic frame and the engine under test are measured to establish the overall coordinate system of the dynamic frame. Secondly, the angular deflection between the local coordinate system of the dynamic frame and the overall coordinate system of the dynamic frame in the force measuring assembly is calculated, and the three-directional force components of the sensor position in the overall coordinate system of the dynamic frame are calculated in combination with the force measuring direction of the sensor. Finally, the input multi-dimensional force can be decoupled through the deflection between the overall coordinate system of the dynamic frame and the global coordinate system.

2. A multi-dimensional force decoupling method based on overall and local displacement of a test system according to claim 1, characterized in that: The following steps are involved: Step 1: Displacement measurement of the test system under the combined force The test system mainly includes five parts: an engine model, a dynamic frame, a plurality of force measuring components, a fixed frame, and a resultant force generating device, wherein the fixed frame is fixed; the engine model is the object to be tested, which is fixedly connected to the dynamic frame, and no displacement occurs between the two; the dynamic frame is an engine supporting structure, the inner side of which is fixed to the engine, and the outer side is connected to the force measuring components; the force measuring components are arranged between the dynamic frame and the fixed frame, and each force measuring component contains a unidirectional force sensor in the middle, which is used to measure the external force on the engine; a resultant force generating device is arranged at one end of the test system, which is used to generate a standard resultant force, and the resultant force can be decomposed into three directional components in the X, Y, and Z directions; the engine axial direction is defined as the X direction, the vertical direction as the Z direction, and the horizontal direction as the Y direction, as the global coordinate system; Displacement measuring devices in two directions are arranged at the connection parts on both sides of the unidirectional force sensor in each force measuring assembly, and displacement measuring devices are arranged on the three adjacent sides of the dynamic frame; a resultant force is applied to one end of the engine through a resultant force generating device; a step loading method is adopted, and the loading is repeated multiple times, and the output data of the unidirectional force sensor in each force measuring assembly is recorded, and the average value of multiple experimental data is taken as F i (i=1,2,3···); measure the output values ​​of the displacement measuring device at the upper and lower positions of the unidirectional force sensor in each force measuring assembly and the displacement measuring device on the dynamic frame after each step loading is stabilized, and also take the average value of multiple experimental measurement results, and finally obtain the local three-dimensional displacement of the dynamic frame at the connecting parts on both sides under the force of the unidirectional force sensor in the force measuring assembly, and establish the local coordinate system of the dynamic frame at the center of the unidirectional force sensor; at the same time, measure the overall three-dimensional displacement components of the dynamic frame and the engine under test, and establish the overall coordinate system of the dynamic frame; Step 2: Establish a local coordinate system and calculate the offset angle According to the measured three-dimensional displacement of the connecting structure on both sides of the unidirectional force sensor in the force measuring assembly, the axial coordinate axis deflection vector Zi0 (i=1, 2, 3···) in the local coordinate system of the sensor is determined, and the axial coordinate axis direction angle after the sensor is deflected is obtained; the displacement measurement data of two end points in three directions of the entire movable frame are processed to obtain the vector of each coordinate axis of the overall coordinate system of the movable frame in the global coordinate system; the angle between the coordinate axis of the axial direction of the unidirectional force sensor in the local coordinate system of each force measuring assembly and the overall coordinate system of the movable frame is calculated, and a relationship model between the sensor measurement direction and the three directions of the movable frame is established to provide an angle reference for multi-dimensional force decoupling calculation; Step 3: Decoupling of test system output data According to the angular relationship between the overall coordinate system of the moving frame and the local coordinate system of the sensors of each force measuring component, the output force value of the unidirectional force sensor in each force measuring component is decomposed according to the overall coordinate system of the moving frame to obtain the three-directional force components in the overall coordinate system of the moving frame. The three-directional force components of the unidirectional force sensors in each force measuring component in the moving frame coordinate system are added to obtain the output force values ​​in the three directions in the overall coordinate system of the moving frame. The output data can then be decoupled through the rotation angle of the three coordinate axes of the moving frame coordinate system in the global coordinate system.

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