Two-degree-of-freedom micro-aerodynamic measurement device

Abstract

This invention discloses a two-degree-of-freedom micro-aerodynamic force measurement device. The device includes vertically arranged X-axis and Y-axis Roberval balancing structures. The Y-axis Roberval balancing structure is embedded within and orthogonally installed to the X-axis Roberval balancing structure. The X-axis Roberval balancing structure has an X-axis linkage bridge support composed of two X-axis linkages (front and rear), which serves as the support frame for the entire Y-axis Roberval balancing structure and drives its movement along the X-axis. The Y-axis Roberval balancing structure also includes a model support structure composed of two Y-axis linkages (left and right), which accurately transmits the aerodynamic forces acting on the model to the X and Y axes. This invention, through its two-degree-of-freedom design, micro-Newton-level sensitivity, and high load compatibility, successfully unifies the three key performance indicators of "multi-dimensionality, high precision, and large load," providing a powerful tool for fundamental research in aerospace aerodynamics.

Description

Technical Field

[0001] This invention belongs to the field of aerodynamic experimental technology, specifically relating to a two-degree-of-freedom micro-aerodynamic force measurement device for gas dynamics research in hypersonic rarefied gas wind tunnels. Background Technology

[0002] To meet the research needs of aerodynamic characteristics for cutting-edge aerospace missions such as near-space hypersonic vehicles and extremely low-Earth orbit satellites, rarefied wind tunnel testing has become a core means to reveal the interaction mechanism between rarefied flow fields and vehicles. One of its key technologies is to achieve accurate measurement of multi-degree-of-freedom aerodynamic forces under small force ranges from microNewtons to millinewtons.

[0003] Existing micro-aerodynamic force measurement schemes are mainly divided into two categories: one is a balance based on a single-degree-of-freedom oscillating structure. Its structure is simple, but it can only provide force or torque information in a single direction, and the measurable force range is usually small (for example, it can only cover about 100 grams). The reason for the small force range is that the single-degree-of-freedom oscillating structure has a small load-bearing capacity because its oscillation structure is in the horizontal direction, and the pivot load of the horizontal oscillation structure is relatively weak.

[0004] Another type is the traditional six-degree-of-freedom strain balance, which uses a strain gauge structure. Although it can achieve simultaneous measurement of multiple components, its sensitivity is severely insufficient in measuring small forces at the micro-Newton level: a force in the X direction will also affect the Y direction, and vice versa. At the same time, limited by structural stiffness and strain gauge sensitivity, its load capacity is usually limited to tens to hundreds of grams, making it difficult to support test models weighing more than one kilogram, which greatly limits its application in larger models or under higher load conditions.

[0005] Therefore, existing technologies suffer from the following prominent contradictions: single-degree-of-freedom balances cannot acquire complete aerodynamic coupling information and can only cover a weight range of approximately 100 grams; while traditional six-degree-of-freedom strain balances, when extending to high sensitivity at the micro-Newton level, often sacrifice load capacity and measurement accuracy, making them unsuitable for advanced aircraft model testing that requires extremely high force measurement accuracy despite their large weight. This technological bottleneck severely restricts the research and verification of high-precision aerodynamic characteristics for extremely rarefied flow environments. Summary of the Invention

[0006] This invention addresses the problems of existing technologies by proposing a two-degree-of-freedom micro-aerodynamic force measurement device. The purpose is to solve the problems that existing single-degree-of-freedom balances cannot obtain complete aerodynamic coupling information and can only cover the scale of about 100 grams; while traditional six-degree-of-freedom strain balances, when extending to high sensitivity at the micro-Newton level, often sacrifice load capacity and measurement accuracy, making them unsuitable for advanced aircraft model tests that require extremely high force measurement accuracy despite their large weight.

[0007] To solve its technical problems, the present invention proposes the following technical solutions. A dual-degree-of-freedom micro-aerodynamic force measuring device, characterized in that: the measuring device is provided with a vertically arranged X-axis Roberval balancing structure and a vertically arranged Y-axis Roberval balancing structure; the vertically arranged Y-axis Roberval balancing structure is embedded in the vertically arranged X-axis Roberval balancing structure and is orthogonally installed to the vertically arranged X-axis Roberval balancing structure; the vertically arranged X-axis Roberval balancing structure is provided with an X-axis linkage bridge bracket composed of two X-axis linkage rods, the X-axis linkage... The rod bridge support serves as the support frame for the entire Y-axis Roberval balance structure, driving the Y-axis Roberval balance structure to move together along the X-axis. The Y-axis Roberval balance structure is equipped with a model support structure consisting of two Y-axis linkage rods on the left and right. A model support rod (2-10) is installed on the model support structure. The model support rod (2-10) is shared by the X-axis Roberval balance structure and the Y-axis Roberval balance structure. The aerodynamic force on the model is accurately transmitted to the X-axis and Y-axis through the model support rod (2-10).

[0008] Furthermore, the model support rod (2-10) is composed of a horizontal support rod and a vertical support rod; an M6 threaded hole is provided on the windward end face of the horizontal straight rod for fixing the model; a horizontal protective sleeve (2-13-1) with a circular cross-section is provided around the horizontal straight rod; a gap is provided between the model support rod (2-10) and the horizontal protective sleeve (2-13-1), which allows the model support rod (2-10) to perform small multi-degree-of-freedom movements when subjected to force in any direction; a blade-shaped vertical protective sleeve (2-13-2) is provided around the vertical support rod, which is made of aluminum alloy.

[0009] Further, the vertically arranged X-axis Roberval balancing structure includes: two parallel X-axis parallelogram balancing structures, an X-axis linkage bridge support between them, an X-axis calibrator (1-10), an X-axis damper (1-9), an X-axis displacement sensor probe (1-11), an X-axis counterweight rod (1-6), and an X-axis counterweight (1-7); the two parallel X-axis parallelogram balancing structures include a front X-axis parallelogram balancing structure and a rear X-axis parallelogram balancing structure; the front X-axis parallelogram balancing structure consists of a horizontally arranged front X-axis linkage rod (1-3-1), front X-axis A swing arms (1-5-1) and front X-axis B swing arms (1-5-2) on both sides of the front X-axis linkage rod (1-3-1), and a front X-axis horizontal base (1-4-1) connecting the lower ends of the front X-axis A swing arms (1-5-1) and the front X-axis B swing arms (1-5-2); the rear X-axis parallelogram balancing structure consists of... The system consists of a horizontally arranged rear X-axis linkage rod (1-3-2), rear X-axis C-arms (1-5-3) and rear X-axis D-arms (1-5-4) on both sides of the rear X-axis linkage rod (1-3-2), and a rear X-axis horizontal base (1-4-2) connecting the lower ends of the rear X-axis C-arms and rear X-axis D-arms; a front X-axis linkage rod (1-3-1) and its two sides, front X-axis A-arms (1-5-1) and front X-axis B-arms (1-5-2), and a rear X-axis linkage rod (1- 3-2) and its two sides, the rear X-axis C-arm (1-5-3) and the rear X-axis D-arm (1-5-4), are connected by the X-axis motion pivot (1-1); the front X-axis A-arm (1-5-1), the front X-axis B-arm (1-5-2) and the front X-axis horizontal base (1-4-1), as well as the rear X-axis C-arm (1-5-3), the rear X-axis D-arm (1-5-4) and the rear X-axis horizontal base (1-4-2), are connected by the X-axis fixed pivot (1-2); The X-axis motion pivot (1-1) and the X-axis fixed pivot (1-2) are arranged in a flat position.

[0010] Furthermore, the X-axis linkage bridge bracket serves as the support frame for the entire Y-axis Roberval balance structure. Specifically, the X-axis linkage bridge bracket is composed of a front X-axis linkage rod (1-3-1) and a rear X-axis linkage rod (1-3-2) that are parallel to each other, and a first U-shaped connecting rod (1-8-1) and a second U-shaped connecting rod (1-8-2) that are parallel to each other. The first U-shaped connecting rod (1-8-1) and the second U-shaped connecting rod (1-8-2) have their openings facing upwards, and the two ends of their respective openings are connected to the front X-axis linkage rod (1-3-1) one in front and one behind. -1) and the rear X-axis linkage (1-3-2), and the first U-shaped link (1-8-1) and the second U-shaped link (1-8-2) are each provided with two U-shaped link fixing pivots (2-2) spaced at a certain distance, and the two U-shaped link fixing pivots of the first U-shaped link and the two U-shaped link fixing pivots of the second U-shaped link are symmetrically arranged. The entire Y-axis Roberval balance structure is orthogonally fixed on the X-axis linkage bridge bracket by the two U-shaped link fixing pivots (2-2) of the first U-shaped link and the two U-shaped link fixing pivots (2-2) of the second U-shaped link.

[0011] Furthermore, the vertically arranged Y-axis Roberval balancing structure includes: two downward-facing Y-axis U-shaped balancing structures orthogonally installed to the two X-axis parallelogram balancing structures; a model support rod (2-10) and a support structure (2-11); a Y-axis calibrator (2-7); a Y-axis damper (2-6); a Y-axis displacement sensor probe (2-12); a Y-axis counterweight rod (2-9); and a Y-axis counterweight (2-8). The two downward-facing and parallel Y-axis U-shaped balancing structures include a left Y-axis U-shaped balancing structure and a right Y-axis U-shaped balancing structure. The left Y-axis U-shaped balancing structure consists of a left Y-axis linkage rod (2-3-1) horizontally arranged in the front-rear direction and a left front Y-axis A swing arm (2-5-1) and a left rear Y-axis B swing arm (2-5-2) perpendicular to it and arranged at its front and rear ends. The right Y-axis U-shaped balancing structure consists of a right Y-axis linkage rod (2-3-2) horizontally arranged in the front-rear direction. It consists of the right front Y-axis C-arm (2-5-3) and the right rear Y-axis D-arm (2-5-4) which are perpendicular to it and arranged at its front and rear ends; The left front Y-axis A swing arm (2-5-1) and the left rear Y-axis B swing arm (2-5-2) are each connected to the left Y-axis linkage rod (2-3-1) via the Y-axis motion pivot (2-1) at the ends away from the U-shaped opening; the right front Y-axis C swing arm (2-5-3) and the right rear Y-axis D swing arm (2-5-4) are each connected to the right Y-axis linkage rod (2-3-2) via the Y-axis motion pivot (2-1) at the ends away from the U-shaped opening; the left front Y-axis A swing arm (2-5-1), the left rear Y-axis B swing arm (2-5-2), the right front Y-axis C swing arm (2-5-3), and the right rear Y-axis D swing arm (2-5-4) are each connected to the X-axis linkage rod bridge bracket via the U-shaped connecting rod pivot (2-2); the Y-axis motion pivot (2-1) and the U-shaped connecting rod pivot (2-2) are laid flat.

[0012] Furthermore, the two Y-axis linkage rods of the Y-axis Roberval balance structure serve as the support structure (2-11) for the model support rod (2-10). Specifically, a horizontal support structure (2-11) perpendicular to the left Y-axis linkage rod (2-3-1) and the right Y-axis linkage rod (2-3-2) is built between them. Vertical support rods and vertical protective sleeves (2-13-2) perpendicular to the model support rod (2-10) are arranged on the horizontal support structure (2-11).

[0013] Furthermore, the precise transmission of aerodynamic force to the X and Y axes via the model support rod (2-10) is specifically as follows: the model is installed at the windward end of the model support rod (2-10). When the airflow blows towards the model, the component force in the X direction acts on the front X-axis linkage rod (1-3-1) and the rear X-axis linkage rod (1-3-2). At this time, the front X-axis linkage rod (1-3-1) and the rear X-axis linkage rod (1-3-2) will undergo displacement in the X direction. The minute aerodynamic force in the X direction is measured by the X-axis displacement sensor probe (1-11). The component force in the Y direction acts on the left Y-axis linkage rod (2-3-1) and the right Y-axis linkage rod (2-3-2). At this time, the left Y-axis linkage rod (2-3-1) and the right Y-axis linkage rod (2-3-2) will undergo displacement in the Y direction. The minute aerodynamic force in the Y direction is measured by the Y-axis displacement sensor probe (2-12).

[0014] Furthermore, the X-axis Roberval balancing structure and the Y-axis Roberval balancing structure are also provided with a platform protective cover (3). The platform protective cover (3) is provided with an upper cover plate (3-1) and a lower cover plate (3-2). The upper cover plate (3-1) and the lower cover plate (3-2) are connected by four fixed support rods (3-3). The lower cover plate (3-2) is used to install the vertically arranged X-axis Roberval balancing structure and the vertically arranged Y-axis Roberval balancing structure. The upper cover plate (3-1) is used to fix the vertical protective sleeve (2-13-2) of the model support rod (2-10). Four support legs (4) are also installed under the lower cover plate (3-2). The height of the four support legs (4) is adjustable.

[0015] Advantages and effects of the present invention

[0016] 1. Enhanced Measurement Dimensions and Completeness: Simultaneous Dual-Degree-of-Freedom Measurement: Aerodynamic data in both the X and Y axes can be acquired simultaneously. This overcomes the limitations of single-degree-of-freedom balances, revealing more comprehensive aerodynamic coupling characteristics and providing a complete data foundation for the analysis of complex aerodynamic phenomena.

[0017] 2. Achieving micro-Newton (μN) level measurements: Through structural optimization and high-precision sensors, it possesses the capability to measure extremely small aerodynamic forces in environments such as extremely rarefied flow fields. This solves the problem of insufficient sensitivity of traditional six-degree-of-freedom strain balances at the micro-Newton level, meeting the demands of cutting-edge fields for extremely high measurement accuracy.

[0018] 3. Optimized load capacity and measurement accuracy: While maintaining micro-Newton-level sensitivity, it can support test models weighing over one kilogram. This breaks the traditional dilemma that "increasing sensitivity inevitably sacrifices load capacity," making it possible to perform high-precision force measurement on large-size, heavy models.

[0019] 4. Engineering Applicability for Cutting-Edge Applications: Meeting Key Requirements for Advanced Aircraft Testing: It precisely meets the testing conditions of novel models that are heavy yet require extremely high force measurement accuracy. It provides previously unavailable key technical means for the aerodynamic characteristics research of cutting-edge missions such as near-space hypersonic vehicles and extremely low-Earth orbit satellites.

[0020] This device, through its dual-degree-of-freedom design, micro-Newton-level sensitivity, and high load compatibility, successfully unifies the three key performance indicators of "multi-dimensionality, high precision, and large load," providing a powerful and advanced measurement tool for fundamental aerospace aerodynamic research and the development of advanced aircraft. Attached Figure Description

[0021] Figure 1 This is a diagram showing the internal structure of the dual-degree-of-freedom micro-aerodynamic force measuring device of the present invention. Figure 2 This is a top view of the dual-degree-of-freedom micro-aerodynamic force measurement device of the present invention; Figure 3 This is a schematic diagram of the X-axis linkage rod bridge support of the present invention; Figure 4 This is a three-dimensional view of the Roberval balance structure on the X-axis of the present invention; Figure 5 This is a three-dimensional view of the Y-axis Roberval balance structure of the present invention; Figure 6 This is a side view of the Roberval balance structure along the X-axis of the present invention; Figure 7 This is a side view of the Y-axis Roberval balance structure of the present invention; Figure 8 This is an external view of the dual-degree-of-freedom micro-aerodynamic force measuring device of the present invention; Figure 9 A schematic diagram showing a gap between the support rod and the transverse protective sleeve in the model of this invention; 1-1: X-axis motion pivot; 1-2: X-axis fixed pivot; 1-3-1: Front X-axis connecting rod; 1-3-2: Rear X-axis connecting rod; 1-4-1: Front X-axis horizontal base; 1-4-2: Rear X-axis horizontal base; 1-5-1: Front X-axis A swing arm; 1-5-2: Front X-axis B swing arm; 1-5-3: Rear X-axis C swing arm; 1-5-4: Rear X-axis D swing arm; 1-6: Counterweight rod; 1-7: X-axis counterweight; 1-8-1: First U-shaped connecting rod; 1-8-2: Second U-shaped connecting rod; 1-9: X-axis damper; 1-10: X-axis calibrator; 1-11: X-axis displacement sensor probe 2-1: Y-axis motion pivot; 2-2: U-shaped connecting rod pivot; 2-3-1: Left Y-axis connecting rod; 2-3-2: Right Y-axis connecting rod; 2-4: Model mounting hole; 2-5-1: Left Y-axis A swing arm; 2-5-2: Left Y-axis B swing arm; 2-5-3: Right Y-axis C swing arm; 2-5-4: Right Y-axis D swing arm; 2-6: Y-axis damper; 2-7: Y-axis calibrator; 2-8: Y-axis counterweight; 2-9: Y-axis counterweight rod; 2-10: Model support rod; 2-11: Support structure; 2-12: Y-axis displacement sensor probe; 2-13: Pneumatic protective cover; 2-13-1: Horizontal protective sleeve; 2-13-2: Vertical protective sleeve; 3: Platform protective cover; 3-1: Upper cover plate; 3-2: Lower cover plate; 3-3: Fixed support rod; 4: Adjustable support leg; Detailed Implementation

[0022] Innovation of this invention

[0023] One of the innovations is the orthogonally embedded two-DOF Roberval balancing mechanism. It employs a vertically arranged X-axis and Y-axis Roberval balancing structure, with the Y-axis structure embedded within the X-axis structure to achieve orthogonal installation. Advantages: The vertically arranged X and Y-axis Roberval balancing structure allows key pivots (including the X-axis motion pivot, X-axis fixed pivot, Y-axis motion pivot, and U-shaped linkage pivot) to be arranged horizontally. Compared to vertical pivot arrangement, this horizontal pivot arrangement allows for a load capacity more than 10 times greater.

[0024] Second innovation: X-axis bearing supports the Y-axis. The innovative design utilizes the X-axis linkage bridge bracket as the supporting base for the entire Y-axis Roberval balance structure, allowing the Y-axis system to move with the X-axis as a whole. Advantages: Compact and simplified structure, while ensuring mechanical decoupling and independence of X and Y direction measurements.

[0025] The third innovation: Model support and force transmission design. A model support frame consisting of two Y-axis linkage rods is adopted, on which a model support rod shared by the X and Y axes is installed. This achieves efficient and accurate transmission of aerodynamic forces to the two measurement axes, reducing force loss and interference in intermediate links, thereby improving the overall measurement accuracy.

[0026] Fourth innovation: Model support rod and protective design. The model support rod adopts a combination of horizontal and vertical structures. The windward side of the horizontal support rod has threaded holes for easy model installation and fixation. Specially designed horizontal and vertical protective sleeves are provided. This ensures both ease of model installation and effective isolation of airflow interference to the support rod during measurement, guaranteeing data accuracy.

[0027] Through the above comprehensive design, this device effectively solves the problems of incomplete information in single-degree-of-freedom balances and the difficulty in balancing sensitivity and load capacity in traditional six-degree-of-freedom balances. It is particularly suitable for wind tunnel testing of advanced aircraft models with large weight and extremely high force measurement accuracy, and has good prospects for engineering applications.

[0028] Design principle of the invention

[0029] 1. Design principle for achieving high-sensitivity measurement under heavy load 1) Balanced Structure (Based on Roberval Balanced Structure): A. Vertical Layout: A vertical Roberval structure is adopted for the X and Y axes, replacing the traditional horizontal swing structure. Utilizing the compressive strength of the materials, the load is not directly applied to the pivot, but is distributed by the connecting rods, resulting in a significantly higher load-bearing capacity than the horizontal swing structure. Changes in the position of the force application point have little impact on the measurement, improving accuracy and stability. B. Nested Design: The Y-axis structure is embedded in the X-axis structure, supported by the X-axis linkage bridge bracket. Dual-degree-of-freedom measurement is achieved within a limited space, optimizing the force transmission path: aerodynamic force is transmitted directly and efficiently via the model support rod → Y-axis → X-axis bracket. C. Counterweight System: Counterweights are provided on both the X and Y axes. This balances most of the static load (such as self-weight), allowing the sensor to measure only minor changes in aerodynamic force, reducing the requirements for the sensor's range. It also reduces structural deformation caused by gravity.

[0030] 2.) Pivot Layout: A. Pivot Type and Arrangement: The motion and fixed pivots of the X and Y axes are arranged horizontally, which is crucial to ensuring the balance's accuracy, stability, and load-bearing capacity. B. Multi-Pivot Linkage: The Roberval structure is essentially a multi-pivot linkage mechanism, which can distribute the load and improve the overall load-bearing capacity. C. U-Shaped Linkage: The Y-axis structure is orthogonally fixed to the X-axis support by symmetrically arranged U-shaped links to fix the pivots. This enhances the connection stiffness between the X and Y axes, making the overall structure more stable.

[0031] In summary, this invention significantly improves the load-bearing capacity of the device at the mechanical design level by employing a vertical Roberval balancing structure and an optimized pivot layout. Simultaneously, the counterweight design adjusts the operating point of the measurement system to its optimal range, allowing it to detect only minute changes caused by aerodynamic forces, thus achieving micro-Newton level high-sensitivity measurements under large model loads. This design effectively resolves the contradiction between load-bearing capacity and measurement sensitivity in traditional technologies, making it suitable for advanced aircraft wind tunnel testing where both weight and force measurement accuracy are extremely demanding.

[0032] 2. Decoupling Design Principle of Two-Degree-of-Freedom Balanced Structure 1) Geometric Structure Basis: The orthogonally arranged Roberval balancing structure geometrically eliminates direct motion coupling between the two measurement directions. The Roberval balancing structures for the X and Y axes are embedded perpendicularly to each other like a "cross." The Y-axis structure is mounted entirely on top of the X-axis structure, and its direction of motion (Y-direction) is perpendicular to the direction of motion (X-direction) of the X-axis structure. This orthogonal arrangement ensures that translation or deformation in one direction will theoretically not directly cause changes in sensor readings in the other direction, laying the physical foundation for decoupling.

[0033] 2) Core of mechanical transmission: Precisely controlled independent force paths are the key to achieving decoupling functionality.

[0034] A. Layered Support: The X-axis structure acts as a "moving platform," supporting the entire Y-axis structure and its appendages as they move along the X-direction. This means that the weight and inertia of the Y-axis system are already included in the X-axis system and will not appear as interfering forces in the Y-axis measurement. B. Force Flow Separation: X-direction force flow: The aerodynamic force acting on the model in the X direction → is transmitted through the shared model support rod → mainly to the front and rear X-axis linkage rods → driving the X-axis balance structure to generate measurement signals. C. Y-direction force flow: The aerodynamic force acting on the model in the Y direction → is transmitted through the same shared model support rod → mainly to the left and right Y-axis linkage rods → driving the Y-axis balance structure to generate measurement signals. D. Key Role of the Shared Support Rod: The model support rod is the sole force input point. It ensures that the X and Y directions measure the two orthogonal components of the aerodynamic force at the same point of application and at the same moment, fundamentally avoiding torque coupling errors introduced by different force application points.

[0035] 3) Auxiliary Protection Measures: Protection and Detailed Design: A. Horizontal Protective Sleeve (Circular Cross-section + Gap): Allows the model support rods to perform small, multi-degree-of-freedom movements under forces in any direction, avoiding "jamming" or additional forces caused by contact friction, and ensuring smooth transmission of minute force signals. B. Vertical Protective Sleeve (Blade-shaped): Presumably, its purpose is to minimize the contact area and reduce frictional interference while allowing necessary movement. The aluminum alloy material ensures rigidity and lightweight design.

[0036] In summary, this invention solves the coupling problem of traditional strain gauges at the microNewton level through a combination of technologies: Utilizing the mechanical properties of the Roberval equilibrium structure, force measurement is transformed into the measurement of equilibrium torque, which is independent of the specific point of application of the force, simplifying the force transmission relationship. Through an orthogonal embedded rigid mechanical structure, the X and Y degrees of freedom in the motion directions are physically separated. The design of "layered support" and "independent force paths" mechanically guides the X and Y components of the force into their respective measurement chains, preventing interference. The "shared model support" unifies the force application points, avoiding parasitic torques. A carefully designed protective sleeve minimizes mechanical constraints and friction in non-measurement directions. Ultimately, these designs work together to ensure that the X-axis and Y-axis sensors are sensitive almost exclusively to the aerodynamic components in their respective directions, thus achieving highly sensitive, low-coupling, and precise independent measurement of microNewton-level aerodynamic forces.

[0037] Based on the above principles, this invention designs a two-degree-of-freedom micro-aerodynamic force measurement device, such as... Figure 1-9 As shown, its features are as follows: the measuring device is equipped with a vertically arranged X-axis Roberval balancing structure and a vertically arranged Y-axis Roberval balancing structure; the vertically arranged Y-axis Roberval balancing structure is embedded in the vertically arranged X-axis Roberval balancing structure and is installed orthogonally to the vertically arranged X-axis Roberval balancing structure; the vertically arranged X-axis Roberval balancing structure is equipped with an X-axis linkage rod bridge bracket composed of two X-axis linkage rods, which serves as the support frame for the entire Y-axis Roberval balancing structure and drives the Y-axis Roberval balancing structure to move together along the X-axis; the Y-axis Roberval balancing structure is equipped with a model support structure composed of two Y-axis linkage rods, and a model support rod (2-10) is installed on the model support structure. The model support rod (2-10) is shared by the X-axis Roberval balancing structure and the Y-axis Roberval, and the aerodynamic force on the model is accurately transmitted to the X-axis and Y-axis through the model support rod (2-10).

[0038] like Figure 9 As shown, the model support rod 2-10 is composed of a horizontal support rod and a vertical support rod; an M6 threaded hole is provided on the windward end face of the horizontal straight rod for fixing the model; a horizontal protective sleeve 2-13-1 with a circular cross-section is provided around the horizontal straight rod; a gap is provided between the model support rod 2-10 and the horizontal protective sleeve 2-13-1, which allows the model support rod 2-10 to perform small multi-degree-of-freedom movements when subjected to force in any direction; a blade-shaped vertical protective sleeve 2-13-2 is provided around the vertical support rod, which is made of aluminum alloy.

[0039] like Figure 4 , Figure 6 As shown, the vertically arranged X-axis Roberval balancing structure includes: two parallel X-axis parallelogram balancing structures, an X-axis linkage bridge support between them, an X-axis calibrator 1-10, an X-axis damper 1-9, an X-axis displacement sensor probe 1-11, an X-axis counterweight rod 1-6, and an X-axis counterweight 1-7. The two parallel X-axis parallelogram balancing structures include a front X-axis parallelogram balancing structure and a rear X-axis parallelogram balancing structure. The front X-axis parallelogram balancing structure consists of a horizontally arranged front X-axis linkage rod 1-3-1, front X-axis A swing arms 1-5-1 and front X-axis B swing arms 1-5-2 on both sides of the front X-axis linkage rod 1-3-1, and a front X-axis horizontal base 1-4-1 connecting the lower ends of the front X-axis A swing arms (1-5-1) and the front X-axis B swing arms 1-5-2. The rear X-axis parallelogram balancing structure consists of a horizontally arranged rear... The system consists of X-axis linkage 1-3-2, rear X-axis C-arms 1-5-3 and rear X-axis D-arms 1-5-4 on both sides of the rear X-axis linkage 1-3-2, and a rear X-axis horizontal base 1-4-2 connecting the lower ends of the rear X-axis C-arms and rear X-axis D-arms; and the system also includes front X-axis linkage 1-3-1 and its two sides, front X-axis A-arms 1-5-1 and front X-axis B-arms 1-5-2, as well as rear X-axis linkage 1-3-2 and its two sides, rear X-axis C-arms. 1-5-3 and the rear X-axis D swing arm 1-5-4 are connected by X-axis motion pivot 1-1; the front X-axis A swing arm 1-5-1, the front X-axis B swing arm 1-5-2 and the front X-axis horizontal base 1-4-1, as well as the rear X-axis C swing arm 1-5-3, the rear X-axis D swing arm 1-5-4 and the rear X-axis horizontal base 1-4-2 are connected by X-axis fixed pivot 1-2; the X-axis motion pivot 1-1 and the X-axis fixed pivot 1-2 are laid flat.

[0040] like Figure 3As shown, the X-axis linkage bridge bracket serves as the support frame for the entire Y-axis Roberval balance structure. Specifically, the X-axis linkage bridge bracket is composed of a front X-axis linkage 1-3-1 and a rear X-axis linkage 1-3-2 that are parallel to each other, and a first U-shaped connecting rod 1-8-1 and a second U-shaped connecting rod 1-8-2 that are parallel to each other. The first U-shaped connecting rod 1-8-1 and the second U-shaped connecting rod 1-8-2 have their openings facing upwards, and the two ends of their respective openings are connected to the front X-axis linkage 1-3-1 and the rear X-axis linkage 1-3-2 respectively. 1 and the rear X-axis linkage 1-3-2, and the first U-shaped link 1-8-1 and the second U-shaped link 1-8-2 are each provided with two U-shaped link fixing pivots 2-2 spaced at a certain distance, and the two U-shaped link fixing pivots of the first U-shaped link and the two U-shaped link fixing pivots of the second U-shaped link are symmetrically arranged. The entire Y-axis Roberval balance structure is orthogonally fixed on the X-axis linkage bridge bracket through the two U-shaped link fixing pivots 2-2 of the first U-shaped link and the two U-shaped link fixing pivots 2-2 of the second U-shaped link.

[0041] like Figure 5 , Figure 6 , Figure 7 As shown, the vertically arranged Y-axis Roberval balancing structure includes: two downward-facing Y-axis U-shaped balancing structures orthogonally installed to the two X-axis parallelogram balancing structures; model support rods 2-10 and support structures 2-11; a Y-axis calibrator 2-7; a Y-axis damper 2-6; a Y-axis displacement sensor probe 2-12; a Y-axis counterweight rod 2-9; and a Y-axis counterweight 2-8. The two downward-facing, parallel Y-axis U-shaped balancing structures include a left Y-axis U-shaped balancing structure and a right Y-axis U-shaped balancing structure. Figure 5As shown, the left Y-axis U-shaped balancing structure consists of a left Y-axis linkage rod 2-3-1 arranged horizontally in the front-to-back direction, and a left front Y-axis swing arm 2-5-1 and a left rear Y-axis swing arm 2-5-2 arranged perpendicularly to it and at its front and rear ends; the right Y-axis U-shaped balancing structure consists of a right Y-axis linkage rod 2-3-2 arranged horizontally in the front-to-back direction, and a right front Y-axis swing arm 2-5-3 and a right rear Y-axis swing arm 2-5-4 arranged perpendicularly to it and at its front and rear ends. The left front Y-axis A swing arm 2-5-1 and the left rear Y-axis B swing arm 2-5-2, each with their ends away from the U-shaped opening, are connected to the left Y-axis linkage rod (2-3-1) via the Y-axis motion pivot 2-1; the right front Y-axis C swing arm 2-5-3 and the right rear Y-axis D swing arm 2-5-4, each with their ends away from the U-shaped opening, are connected to the right Y-axis linkage rod 2-3-2 via the Y-axis motion pivot 2-1; the left front Y-axis A swing arm 2-5-1, the left rear Y-axis B swing arm 2-5-2, the right front Y-axis C swing arm 2-5-3, and the right rear Y-axis D swing arm 2-5-4, each with their ends near the U-shaped opening, are connected to the X-axis linkage rod bridge bracket via the U-shaped connecting rod pivot 2-2; the Y-axis motion pivot 2-1 and the U-shaped connecting rod pivot 2-2 are arranged horizontally.

[0042] like Figure 5 , Figure 6 As shown, the two Y-axis linkage rods of the Y-axis Roberval balance structure serve as the support structure 2-11 for the model support rod 2-10. Specifically, a horizontal support structure 2-11 perpendicular to the left Y-axis linkage rod 2-3-1 and the right Y-axis linkage rod 2-3-2 is built between them. Vertical support rods and vertical protective sleeves 2-13-2 perpendicular to the model support rod 2-10 are arranged on the horizontal support structure 2-11.

[0043] like Figure 9 As shown, the aerodynamic force on the model is accurately transmitted to the X and Y axes via the model support rod 2-10. Specifically, the model is installed at the windward end of the model support rod 2-10. When the airflow blows towards the model, the component force in the X direction acts on the front X-axis linkage rod 1-3-1 and the rear X-axis linkage rod 1-3-2. At this time, the front X-axis linkage rod 1-3-1 and the rear X-axis linkage rod 1-3-2 will undergo displacement in the X direction. The minute aerodynamic force in the X direction is measured by the X-axis displacement sensor probe 1-11. The component force in the Y direction acts on the left Y-axis linkage rod 2-3-1 and the right Y-axis linkage rod 2-3-2. At this time, the left Y-axis linkage rod 2-3-1 and the right Y-axis linkage rod 2-3-2 will undergo displacement in the Y direction. The minute aerodynamic force in the Y direction is measured by the Y-axis displacement sensor probe 2-12.

[0044] like Figure 8As shown, the X-axis Roberval balancing structure and the Y-axis Roberval balancing structure are also equipped with a platform protective cover 3. The platform protective cover 3 is equipped with an upper cover plate 3-1 and a lower cover plate 3-2. The upper cover plate 3-1 and the lower cover plate 3-2 are connected by four fixed support rods 3-3. The lower cover plate 3-2 is used to install the vertically arranged X-axis Roberval balancing structure and the vertically arranged Y-axis Roberval balancing structure. The upper cover plate 3-1 is used to fix the vertical protective sleeve 2-13-2 of the model support rod 2-10. Four support legs 4 are also installed under the lower cover plate 3-2. The height of the four support legs 4 is adjustable. Example 1

[0045] 1. Device Structure Design: This scheme adopts the Roberval equilibrium principle to design a two-degree-of-freedom micro-aerodynamic force measurement device, realizing aerodynamic force measurement. It integrates the advantages of the torsional pendulum model, such as low requirements for center of mass adjustment and vibration isolation, and good stability, as well as the advantages of the Roberval equilibrium structure, such as linear motion, high precision, anti-interference, and high load capacity. This scheme will not cause the model to deflect the force and has no requirements for the center of thrust action. The displacement sensing is also not a traditional rotational angular displacement measurement, thus improving the linearity of the measurement system; it effectively eliminates the error of lever arm measurement, standard lever arm measurement error, and sensor position measurement error, significantly improving the thrust measurement accuracy. Figure 1 This is a three-dimensional assembly diagram of the measurement platform (drawn using SolidWorks). The platform mainly includes adjustable legs, platform base plate, platform protective sleeve, fixed support rod, platform cover plate, vertical support rod protective sleeve, horizontal support rod protective sleeve and model mounting support rod, as well as the two-degree-of-freedom Roberval balance structure inside the platform protective sleeve.

[0046] Among them, the model mounting support rod is used to mount various aircraft models, and its end is designed with M6 threaded holes; the platform protective sleeve, vertical support rod protective sleeve and horizontal support rod protective sleeve are used to block the high-speed rarefied gas flow and prevent the rarefied gas flow from interfering with the force measuring device; the adjustable support leg is mainly used to adjust the level of the device.

[0047] The overall dimensions of the device are 300mm × 300mm × 600mm, with a total mass ≤ 20kg. This measuring device consists of two decoupled single-degree-of-freedom Roberval equilibrium structures. This multi-degree-of-freedom decoupling design ensures that aerodynamic forces in one direction do not interfere with measurement results in other directions during the measurement process, thus achieving precise separation and independent measurement of the aerodynamic forces acting on the model in three-dimensional space. For example, when the model is subjected to an aerodynamic force along the X-axis, only the Roberval equilibrium structure in the X-axis direction undergoes corresponding displacement, while the structure in the Y-axis direction remains stable, avoiding cross-coupling errors and providing a reliable raw data foundation for subsequent data processing and analysis.

[0048] 2. Roberval balance structure design: The Roberval balance structure for each degree of freedom of the two-degree-of-freedom micro-aerodynamic force is as follows: Figure 2 As shown, the main components include a linkage rod, calibrator, damper, swing arm, displacement sensor probe, pivot, counterweight rod, and counterweight. The X-axis linkage rod serves as the support rod for the entire Y-axis Roberval balance structure, driving the Y-axis to move along the X-axis. The Y-axis linkage rod acts as a fixed support structure for the model, accurately transmitting the aerodynamic forces acting on the model to the X and Y axes. The calibrator consists of a permanent magnet and a coil. The permanent magnet is mounted on the linkage rod, and the coil is fixed to the base plate of the platform via structural components, coaxially and intersecting with the permanent magnet. The damper shares the same structure and installation method as the calibrator; short-circuiting its coil achieves magnetic damping, enabling rapid stabilization of the device. The displacement sensor probe detects the motion state of the swing arm and linkage rod. The pivot, as the core elastic element, bears weight and provides restoring force. The counterweight rod is used to install the counterweight, ensuring controllable center of gravity and further suppressing external environmental noise.

[0049] The red box represents the X-axis Roberval balance structure. The upper swing arm is 150mm long and the lower swing arm is 75mm long. It uses eight H10 and two HD20 type cross-shaped pivots to form an over-constrained parallelogram structure. The design sensitivity of this structure is 5μm / mN. Different design sensitivities can also be achieved by changing the pivot combination.

[0050] It should be emphasized that the above specific embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A dual degree-of-freedom micro-pneumatic force measurement device, characterized by: The measuring device is equipped with a vertically arranged X-axis Roberval balancing structure and a vertically arranged Y-axis Roberval balancing structure. The vertically arranged Y-axis Roberval balancing structure is embedded in the vertically arranged X-axis Roberval balancing structure and is installed orthogonally to the vertically arranged X-axis Roberval balancing structure. The vertically arranged X-axis Roberval balancing structure is equipped with an X-axis linkage bridge bracket composed of two X-axis linkage rods, which serves as the support frame for the entire Y-axis Roberval balancing structure and drives the Y-axis Roberval balancing structure to move together along the X-axis. The Y-axis Roberval balancing structure is equipped with a model support structure composed of two Y-axis linkage rods, and a model support rod (2-10) is installed on the model support structure. The model support rod (2-10) is shared by the X-axis Roberval balancing structure and the Y-axis Roberval balancing structure, and the aerodynamic force on the model is accurately transmitted to the X-axis and Y-axis through the model support rod (2-10).

2. The dual degree-of-freedom micro-pneumatic force measurement device of claim 1, wherein: The model support rod (2-10) is composed of a horizontal support rod and a vertical support rod; an M6 threaded hole is provided on the windward end face of the horizontal straight rod for fixing the model; a horizontal protective sleeve (2-13-1) with a circular cross-section is provided around the horizontal straight rod; a gap is provided between the model support rod (2-10) and the horizontal protective sleeve (2-13-1), which allows the model support rod (2-10) to perform small multi-degree-of-freedom movements when subjected to force in any direction; a blade-shaped vertical protective sleeve (2-13-2) is provided around the vertical support rod, which is made of aluminum alloy.

3. The dual degree-of-freedom micro-pneumatic force measurement device of claim 1, wherein: The vertically arranged X-axis Roberval balancing structure includes: two parallel X-axis parallelogram balancing structures, an X-axis linkage bridge support between them, an X-axis calibrator (1-10), an X-axis damper (1-9), an X-axis displacement sensor probe (1-11), an X-axis counterweight rod (1-6), and an X-axis counterweight (1-7). The two parallel X-axis parallelogram balancing structures include a front X-axis parallelogram balancing structure and a rear X-axis parallelogram balancing structure. The front X-axis parallelogram balancing structure consists of a horizontally arranged front X-axis linkage rod (1-3-1), front X-axis A swing arms (1-5-1) and front X-axis B swing arms (1-5-2) on both sides of the front X-axis linkage rod (1-3-1), and a front X-axis horizontal base (1-4-1) connecting the lower ends of the front X-axis A swing arms (1-5-1) and the front X-axis B swing arms (1-5-2). The rear X-axis parallelogram balancing structure consists of a horizontally arranged front X-axis parallelogram balancing structure. The system consists of a rear X-axis linkage rod (1-3-2), rear X-axis C-arms (1-5-3) and rear X-axis D-arms (1-5-4) on both sides of the rear X-axis linkage rod (1-3-2), and a rear X-axis horizontal base (1-4-2) connecting the lower ends of the rear X-axis C-arms and rear X-axis D-arms; a front X-axis linkage rod (1-3-1) and front X-axis A-arms (1-5-1) and front X-axis B-arms (1-5-2) on both sides of it, and a rear X-axis linkage rod (1-3-4). -2) and its two sides, the rear X-axis C-arm (1-5-3) and the rear X-axis D-arm (1-5-4), are connected by the X-axis motion pivot (1-1); the front X-axis A-arm (1-5-1), the front X-axis B-arm (1-5-2) and the front X-axis horizontal base (1-4-1), as well as the rear X-axis C-arm (1-5-3), the rear X-axis D-arm (1-5-4) and the rear X-axis horizontal base (1-4-2), are connected by the X-axis fixed pivot (1-2); The X-axis motion pivot (1-1) and the X-axis fixed pivot (1-2) are arranged in a flat position.

4. The dual degree-of-freedom micro-pneumatic force measurement device of claim 3, wherein: The X-axis linkage bridge bracket serves as the support frame for the entire Y-axis Roberval balance structure. Specifically, the X-axis linkage bridge bracket is composed of a front X-axis linkage (1-3-1) and a rear X-axis linkage (1-3-2) that are parallel to each other, and a first U-shaped connecting rod (1-8-1) and a second U-shaped connecting rod (1-8-2) that are parallel to each other. The first U-shaped connecting rod (1-8-1) and the second U-shaped connecting rod (1-8-2) have their openings facing upwards, and the two ends of their respective openings are connected to the front X-axis linkage (1-3-1) one in front and one behind. The X-axis linkage (1-3-2) and the first U-shaped link (1-8-1) and the second U-shaped link (1-8-2) are each provided with two U-shaped link fixing pivots (2-2) spaced at a certain distance. The two U-shaped link fixing pivots of the first U-shaped link and the two U-shaped link fixing pivots of the second U-shaped link are symmetrically arranged. The entire Y-axis Roberval balance structure is orthogonally fixed on the X-axis linkage bridge bracket through the two U-shaped link fixing pivots (2-2) of the first U-shaped link and the two U-shaped link fixing pivots (2-2) of the second U-shaped link.

5. The dual degree-of-freedom micro-pneumatic force measurement device of claim 1, wherein: The vertically arranged Y-axis Roberval balancing structure includes: two downward-facing Y-axis U-shaped balancing structures orthogonally installed to the two X-axis parallelogram balancing structures; model support rods (2-10) and support structures (2-11); a Y-axis calibrator (2-7); a Y-axis damper (2-6); a Y-axis displacement sensor probe (2-12); a Y-axis counterweight rod (2-9); and a Y-axis counterweight (2-8). The two downward-facing and parallel Y-axis U-shaped balancing structures include a left Y-axis U-shaped balancing structure and a right Y-axis U-shaped balancing structure. The left Y-axis U-shaped balancing structure consists of a left Y-axis linkage rod (2-3-1) horizontally arranged in the front-rear direction and a left front Y-axis A swing arm (2-5-1) and a left rear Y-axis B swing arm (2-5-2) perpendicular to it and arranged at its front and rear ends. The right Y-axis U-shaped balancing structure consists of a right Y-axis linkage rod (2-3-2) horizontally arranged in the front-rear direction. It consists of the right front Y-axis C-arm (2-5-3) and the right rear Y-axis D-arm (2-5-4) which are perpendicular to it and arranged at its front and rear ends; The left front Y-axis A swing arm (2-5-1) and the left rear Y-axis B swing arm (2-5-2) are each connected to the left Y-axis linkage rod (2-3-1) via the Y-axis motion pivot (2-1) at the ends away from the U-shaped opening; the right front Y-axis C swing arm (2-5-3) and the right rear Y-axis D swing arm (2-5-4) are each connected to the right Y-axis linkage rod (2-3-2) via the Y-axis motion pivot (2-1) at the ends away from the U-shaped opening; the left front Y-axis A swing arm (2-5-1), the left rear Y-axis B swing arm (2-5-2), the right front Y-axis C swing arm (2-5-3), and the right rear Y-axis D swing arm (2-5-4) are each connected to the X-axis linkage rod bridge bracket via the U-shaped connecting rod pivot (2-2); the Y-axis motion pivot (2-1) and the U-shaped connecting rod pivot (2-2) are laid flat.

6. The dual degree-of-freedom micro-pneumatic force measurement device of claim 5, wherein: The two Y-axis linkage rods of the Y-axis Roberval balance structure serve as the support structure (2-11) for the model support rod (2-10). Specifically, a horizontal support structure (2-11) perpendicular to the left Y-axis linkage rod (2-3-1) and the right Y-axis linkage rod (2-3-2) is built between them. Vertical support rods and vertical protective sleeves (2-13-2) perpendicular to the model support rod (2-10) are arranged on the horizontal support structure (2-11).

7. The dual degree-of-freedom micro-pneumatic force measurement device of claim 6, wherein: The aerodynamic force on the model is accurately transmitted to the X and Y axes via the model support rod (2-10). Specifically, the model is installed at the windward end of the model support rod (2-10). When the airflow blows towards the model, the component force in the X direction acts on the front X-axis linkage rod (1-3-1) and the rear X-axis linkage rod (1-3-2). At this time, the front X-axis linkage rod (1-3-1) and the rear X-axis linkage rod (1-3-2) will undergo displacement in the X direction. The minute aerodynamic force in the X direction is measured by the X-axis displacement sensor probe (1-11). The component force in the Y direction acts on the left Y-axis linkage rod (2-3-1) and the right Y-axis linkage rod (2-3-2). At this time, the left Y-axis linkage rod (2-3-1) and the right Y-axis linkage rod (2-3-2) will undergo displacement in the Y direction. The minute aerodynamic force in the Y direction is measured by the Y-axis displacement sensor probe (2-12).

8. The dual degree-of-freedom micro-pneumatic force measurement device of claim 1, wherein: The X-axis Roberval balancing structure and the Y-axis Roberval balancing structure are also equipped with a platform protective cover (3). The platform protective cover (3) is equipped with an upper cover plate (3-1) and a lower cover plate (3-2). The upper cover plate (3-1) and the lower cover plate (3-2) are connected by four fixed support rods (3-3). The lower cover plate (3-2) is used to install the vertically arranged X-axis Roberval balancing structure and the vertically arranged Y-axis Roberval balancing structure. The upper cover plate (3-1) is used to fix the vertical protective sleeve (2-13-2) of the model support rod (2-10). Four support legs (4) are also installed under the lower cover plate (3-2). The height of the four support legs (4) is adjustable.

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