Aerodynamic load simulation applying system and method for undercarriage folding and unfolding test
By using a closed-loop control system and rigid connection, combined with a load-angle relationship model and real-time feedback signals, high-precision dynamic simulation of the load during landing gear retraction and extension was achieved, solving the problem of inaccurate load simulation in existing technologies and improving the realism and safety of the test.
Patent Information
- Application Number
- CN202610110466.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-03-06
AI Technical Summary
Existing technologies struggle to achieve real-time, high-precision simulation of load magnitude and direction during landing gear retraction and extension, and in particular, they cannot effectively simulate the effects of dynamic changes in aerodynamic forces and alternating loads, thus affecting the authenticity and validity of the test.
A closed-loop control system is adopted, including a control and processing unit, a measurement and sensing unit, and a loading and execution unit. Through the load-angle relationship model and real-time feedback signal, the loading motor is used to simulate aerodynamic loads. Torque is transmitted by a rigid connection method. Dynamic and nonlinear load simulation is achieved by combining open-loop and closed-loop control strategies.
It achieves high-precision and dynamic simulation of aerodynamic loads, improving the realism, safety and efficiency of the test. The system has a compact structure and a high degree of automation, which significantly improves the reliability and repeatability of landing gear retraction and extension tests.
Smart Images
Figure CN121608893A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft ground testing technology, and in particular to an aerodynamic load simulation application system and method for landing gear retraction and extension tests. Background Technology
[0002] In ground-based tests of aircraft landing gear retraction and reliability, it is necessary to simulate the aerodynamic loads experienced by the landing gear during flight retraction and deployment to accurately reproduce its in-flight load conditions. This simulation is crucial for verifying the kinematic performance, structural strength, and coordination with the airborne systems of the landing gear mechanism.
[0003] Currently, common simulation loading methods mainly include the following two categories:
[0004] One method is the equivalent weight loading method, which applies load by directly suspending a counterweight on the landing gear or using levers. While this method is simple and easy to implement, it can only provide a constant or finitely graded static load and cannot achieve continuous and dynamic changes in load as the landing gear retraction angle changes. In addition, the inertia of the counterweight itself will affect the real-time performance of the loading, making it difficult to accurately reflect the dynamic characteristics of the aerodynamic load.
[0005] The second method is the motor-driven rope loading method, which applies varying tension to the landing gear via a motor and rope. While this method can achieve a certain degree of load variation, the loading direction is usually fixed and cannot simulate the alternating load direction with angle during actual landing gear movement. Furthermore, this type of system is typically loosely structured, occupies a large area, and has limited loading accuracy and control response speed.
[0006] In summary, existing technologies struggle to simulate the real-time, high-precision matching of load magnitude and direction with angle across the entire landing gear retraction and extension trajectory. In particular, they cannot effectively simulate the effects of dynamic aerodynamic changes and alternating loads, thus limiting the realism and effectiveness of the experiments. Therefore, there is an urgent need to develop an aerodynamic load application system and method capable of precise, dynamic, closed-loop control and the simulation of alternating load characteristics. Summary of the Invention
[0007] The purpose of this invention is to provide a pneumatic load simulation application system and method for landing gear retraction and extension tests, in order to solve the technical problems that traditional counterweight loading methods cannot dynamically and accurately simulate nonlinear changes with the retraction and extension angles and that motor-driven rope methods cannot simulate alternating loads.
[0008] As a first aspect of the present invention, the present invention provides an aerodynamic load simulation application system for landing gear retraction and extension tests, comprising: a control and processing unit for storing a load-angle relationship model characterizing the aerodynamic load as the landing gear retraction and extension angle changes, and generating control commands based on received feedback signals; a measurement and sensing unit including a torque sensor for real-time measurement of the actual torque applied to the landing gear and an angle sensor for real-time measurement of the landing gear retraction and extension angle, the measurement and sensing unit being signal-connected to the control and processing unit to provide feedback measurement signals; and a loading execution unit including a loading motor operating in torque mode, the drive end of the loading motor being rigidly connected to the rotating part of the landing gear strut to be tested, for outputting torque according to the control commands issued by the control and processing unit to simulate aerodynamic loads; wherein the control and processing unit, the measurement and sensing unit, and the loading execution unit constitute a closed-loop control system.
[0009] Optionally, the control and processing unit includes a PLC controller, which pre-stores the load-angle relationship model and integrates a PID control module.
[0010] Optionally, the control and processing unit further includes an analog input module and a digital input module for receiving feedback signals from the measurement sensing unit, and an analog output module and a digital output module for sending control commands to the loading execution unit.
[0011] Optionally, the angle sensor is mounted on the rotational hinge point of the landing gear strut or on a rotating shaft linked thereto.
[0012] Optionally, the loading execution unit further includes a reducer, and the output shaft of the loading motor is rigidly connected to the input end of the torque sensor through the reducer.
[0013] Optionally, the loading execution unit further includes a strut clamp, the output end of the torque sensor is connected to the strut clamp via the landing gear strut shaft, and the strut clamp is used to clamp and fix the rotating part of the landing gear strut.
[0014] As a second aspect of the present invention, the present invention provides an aerodynamic load simulation application method for landing gear retraction and extension tests, based on the aerodynamic load simulation application system for landing gear retraction and extension tests described in any of the preceding claims, the aerodynamic load simulation application method comprising the following steps:
[0015] The system initializes and loads the predetermined load-angle relationship model;
[0016] The current retraction angle of the landing gear is acquired in real time, and the corresponding target torque value is calculated based on the load-angle relationship model.
[0017] The loading execution unit is controlled to start in open-loop control mode, so that its output torque gradually increases from zero to near the target torque value;
[0018] Once the output torque stabilizes, the system switches to closed-loop control mode. Based on the deviation between the actual torque value measured in real time and the target torque value, the output torque of the loading motor is dynamically adjusted to track the target torque curve that changes with the angle with high precision.
[0019] Throughout the entire landing gear retraction and extension process, the system cyclically executes steps for angle acquisition, target value calculation, and torque closed-loop tracking, while continuously monitoring for safety.
[0020] Optionally, in the system initialization step, the upper and lower limits of torque safety operation, PID control parameters, and the gradual rise time of open-loop loading are also set.
[0021] Optionally, after acquiring the angle in real time and calculating the target torque value, the method further includes a step of performing a limit check on the target torque value; if it exceeds the safety boundary, it is limited to a safe value range.
[0022] Optionally, the open-loop control mode startup step specifically involves the control and processing unit outputting an analog voltage signal to the load motor driver, which starts from zero and linearly increases to the target torque value within a preset time.
[0023] Compared with the prior art, the present invention discloses at least the following beneficial effects:
[0024] The aerodynamic load simulation application system and method for landing gear retraction and extension tests disclosed in this invention, through a closed-loop control system composed of a control and processing unit, a measurement and sensing unit, and a loading execution unit, can achieve high-precision and dynamic simulation of aerodynamic loads as the landing gear retraction and extension angle changes. Based on a pre-stored load-angle relationship model, combined with real-time acquired angle and torque feedback signals, the system dynamically adjusts the output torque of the loading motor using a closed-loop control strategy, thereby accurately reproducing the nonlinear changes and alternating characteristics of the aerodynamic load throughout the retraction and extension process. The use of a rigid connection to directly transmit torque not only improves the response speed and transmission efficiency of load application but also avoids problems such as structural looseness and directional limitations caused by traditional rope or counterweight methods. Furthermore, the system smoothly transitions from a progressive open-loop start-up to closed-loop tracking, effectively suppressing the impact of sudden torque changes on the test specimen. The integrated torque limiting, fault monitoring, and safe shutdown mechanisms further enhance the reliability and safety of the test process. The overall system has a compact structure and a high degree of automation, significantly improving the realism, repeatability, and efficiency of landing gear ground retraction and extension tests, and possesses good engineering applicability and promotional value. Attached Figure Description
[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a schematic diagram of the overall structure of the aerodynamic load simulation application system of the present invention;
[0027] Figure 2 This is a schematic diagram of the loading execution unit in the pneumatic load simulation application system of the present invention;
[0028] Figure 3 This is a schematic diagram showing the connection relationship of the loading execution unit in the pneumatic load simulation application system of the present invention;
[0029] Figure 4 This is a control flowchart of the pneumatic load simulation application method of the present invention;
[0030] In the diagram: 1. Control and processing unit; 2. Signal line; 3. Control cable; 4. Measurement and sensing unit; 5. Loading execution unit; 6. Loading motor; 7. Reducer; 8. Torque sensor; 9. Angle sensor; 10. Strut clamp; 11. Landing gear strut; 12. Landing gear strut shaft; 13. Support base. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0033] Example 1
[0034] Reference Figures 1 to 3 As shown, this embodiment provides an aerodynamic load simulation application system for landing gear retraction and extension tests, including a control and processing unit 1, a measurement and sensing unit 4, and a loading execution unit 5. Each unit is electrically connected to the control cable 3 via a signal line 2, forming a highly integrated and compact closed-loop loading system.
[0035] In one specific embodiment, the control and processing unit 1 mainly includes a PLC control cabinet. This control cabinet integrates a PLC controller, analog input / output modules, and digital input / output modules. The PLC controller, as the core of the system, pre-stores a load-angle relationship model characterizing the nonlinear change of aerodynamic load with the landing gear retraction angle. This model can be in the form of a mathematical function or a lookup table. The input interface of the PLC control cabinet receives feedback signals from the measurement sensing unit 4 via signal line 2; its output interface sends control commands to the loading execution unit 5 via control cable 3.
[0036] In one specific embodiment, the measurement sensing unit 4 includes a high-precision torque sensor 8 and an angle sensor 9. The torque sensor 8 is connected in series in the power output path of the loading execution unit 5, and is used to measure the actual torque value applied to the landing gear in real time and directly, and convert it into an analog voltage signal to be fed back to the control and processing unit 1. The angle sensor 9 is preferably installed on the landing gear rotation hinge point or a shaft linked to it, and is used to measure the landing gear retraction angle in real time and accurately, and feed the angle signal back to the control and processing unit 1.
[0037] In one specific embodiment, the loading execution unit 5 is the load application end of the system, and its core consists of a loading motor 6 operating in torque mode and its associated driver. The output shaft of the loading motor 6 is rigidly connected to the input end of the torque sensor 8 via a reducer 7 (e.g., via a key connection) to provide a smooth and sufficiently large output torque. The output end of the torque sensor 8 is connected to a set of strut clamps 10 via the landing gear strut shaft 12. The strut clamps 10 are securely clamped and fixed to the rotating part of the landing gear strut 11 to be tested using bolts or other fasteners. The support base 13 is used to stably support and fix the entire loading execution unit 5 within the test space. Through this rigid connection, the torque output by the loading motor 6 can be directly transmitted to the landing gear strut 11 without intermediaries and with low loss, thereby simulating aerodynamic loads.
[0038] As can be seen from the above structure, the system calculates the target torque based on the real-time angle and adopts a progressive open-loop start-up to avoid impact. It then automatically switches to closed-loop PID control, enabling the motor output torque to track the target load curve with high precision. This invention's system can achieve dynamic, high-precision, and automated simulation of aerodynamic loads, possessing multiple safety mechanisms such as torque limit control and immediate shutdown in case of faults. It significantly improves the realism, safety, and efficiency of the experiment, and the system has a compact structure and strong versatility.
[0039] Example 2
[0040] like Figure 4As shown, this embodiment two provides an aerodynamic load simulation application method for landing gear retraction and extension tests. This method is based on the aerodynamic load simulation application system for landing gear retraction and extension tests described in embodiment one above. This method achieves a fully automatic control process from open-loop smooth start-up to closed-loop precise tracking, specifically including the following steps:
[0041] S1: System initialization and model loading.
[0042] After the system is powered on, the PLC controller in control and processing unit 1 completes initialization. The operator inputs and stores the aerodynamic load spectrum (i.e., the target torque-angle relationship curve or lookup table) with the extension / retraction angle as the variable, which has been determined in advance through theoretical calculations or wind tunnel tests, into the PLC controller. At the same time, key control parameters such as the safe operating upper and lower limits of torque, the proportional, integral, and derivative parameters of the PID control module, and the smooth rise time of open-loop loading (e.g., 5 seconds) are set.
[0043] S2: Safety self-test and standby.
[0044] Upon initiating the test program, the PLC controller first performs a system self-test, monitoring the fault status signals of the loaded motor 6 and its driver via digital input channels. After confirming that all units are fault-free, the system enters standby mode, awaiting the start command.
[0045] S3: Signal synchronization and target value calculation.
[0046] After the test begins, angle sensor 9 continuously collects the real-time retraction and extension angle values of the landing gear and sends them to the PLC controller via signal line 2. Based on the received real-time angle, the PLC controller immediately queries or calculates the pre-stored load-angle model to obtain the target torque value corresponding to the current angle. Subsequently, the PLC controller performs a limit check on the calculated target torque value. If it exceeds the preset safety boundary, it forcibly limits it to the upper or lower safety limit to protect the test piece.
[0047] S4: Progressive open-loop loading startup.
[0048] After confirming that the motor is fault-free and obtaining the verified target torque value, the PLC controller sends an enable signal to the driver of the loading motor 6 via the digital output channel. Simultaneously, the system initially operates in open-loop control mode: the PLC sends an analog voltage signal, starting from zero and linearly and smoothly increasing to the target torque value within a preset time (e.g., 5 seconds), to the driver via the analog output channel. The driver then controls the output torque of the loading motor 6 to gradually increase from zero, avoiding the impact on the landing gear mechanism caused by sudden torque jumps.
[0049] S5: Switch to closed-loop PID precise tracking.
[0050] When the open-loop loading stabilizes, meaning the torque output by the loading motor 6 approaches the target value and changes gradually, the system automatically and seamlessly switches to closed-loop control mode. In this mode, the PID control module built into the PLC controller begins to operate: it continuously reads the actual torque value fed back by the torque sensor 8 and compares it with the target torque value calculated in real time in step S3 to obtain the torque deviation. The PID control module calculates according to a preset algorithm based on this deviation value to generate a real-time torque adjustment command. After the adjustment command undergoes "rate of change limiting" processing (i.e., limiting the amount of torque change in a single adjustment to prevent overshoot or excessively fast response), it is sent to the driver through the analog output channel, thereby finely and dynamically adjusting the output torque of the loading motor 6 to accurately track the target torque curve that changes with angle.
[0051] S6: Full-process dynamic tracking and safety monitoring.
[0052] Throughout the entire landing gear retraction and extension process, the system cyclically executes steps S3 to S5 to achieve full-range dynamic and high-precision simulation of the load. Simultaneously, the PLC controller continuously monitors safety: on one hand, it monitors all fault signals in real time; once any fault is detected (such as overcurrent, overtemperature, or communication interruption), it immediately interrupts the control program, cancels the motor enable signal, instantly reduces the output torque to zero, and the system enters a safe shutdown state; on the other hand, it consistently performs torque limiting protection during closed-loop regulation to ensure that the actual output torque at any time does not exceed the safe range.
[0053] S7: End of test and smooth unloading.
[0054] After the landing gear completes its retraction and extension, the system controls the output torque of the loading motor 6 to gradually decrease from its current value (e.g., linearly decreasing over several seconds) to zero. Subsequently, the PLC controller deactivates the motor enable signal, the loading execution unit 5 disengages from the landing gear, and a complete test process ends.
[0055] Through the above system and method, this invention achieves dynamic, closed-loop, and high-precision simulation of nonlinear and alternating aerodynamic loads during landing gear retraction and extension, significantly improving the realism, safety, and automation level of the test.
[0056] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.
[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A system for simulating application of aerodynamic loads for landing gear retraction and extension tests, characterized in that, The utility model relates to a kind of test system of landing gear aerodynamic load, including: Control and processing unit (1) for storing the load-angle relationship model representing aerodynamic load changes with landing gear retraction angle, and generating control instruction based on received feedback signal; Measurement sensing unit (4) including torque sensor (8) for measuring actual torque applied to landing gear in real time and angle sensor (9) for measuring landing gear retraction angle in real time, the measurement sensing unit (4) is signal connected with the control and processing unit (1) to feedback measurement signal; Load execution unit (5) including load motor (6) working in torque mode, the driving end of the load motor (6) is connected with the rotating part of landing gear strut (11) to be tested by rigid connection, for outputting torque according to the control instruction issued by the control and processing unit (1) to simulate aerodynamic load; Wherein, the control and processing unit (1), measurement sensing unit (4) and load execution unit (5) constitute closed loop control system.
2. The system for simulating aerodynamic load application for landing gear retraction test according to claim 1, wherein, The control and processing unit (1) includes PLC controller, the load-angle relationship model is pre-stored in the PLC controller, and PID control module is integrated.
3. The system for simulating aerodynamic load application for landing gear retraction test according to claim 2, characterized in that, The control and processing unit (1) further includes analog input module and digital input module for receiving feedback signal of the measurement sensing unit (4), and analog output module and digital output module for sending control instruction to the load execution unit (5).
4. The system for simulating aerodynamic load application for landing gear retraction test according to claim 1, wherein, The angle sensor (9) is installed on the rotating hinge point of the landing gear strut (11) or the rotating shaft linked therewith.
5. The system for simulating aerodynamic load application for landing gear retraction test according to claim 1, wherein, The load execution unit (5) further includes reducer (7), and the output shaft of the load motor (6) is rigidly connected with the input end of the torque sensor (8) through the reducer (7).
6. The system for simulating aerodynamic load application for landing gear retraction test according to claim 5, wherein, The load execution unit (5) further includes column clamp (10), and the output end of the torque sensor (8) is connected with the column clamp (10) through landing gear strut rotating shaft (12), and the column clamp (10) is used for clamping and fixing the rotating part of the landing gear strut (11).
7. A method for applying a simulated aerodynamic load for a landing gear retraction test, based on the system for applying a simulated aerodynamic load for a landing gear retraction test according to any one of claims 1 to 6, characterized in that, The utility model relates to a kind of test system of landing gear aerodynamic load, including: System initialization and load predetermined load-angle relationship model; Real-time current retraction angle of landing gear is obtained, and corresponding target torque value is calculated according to the load-angle relationship model; The load execution unit (5) is controlled to start in open loop control mode, so that its output torque gradually increases from zero to the target torque value; When output torque tends to be stable, switch to closed loop control mode, dynamically adjust the output torque of the load motor (6) according to the deviation between actual torque value measured in real time and the target torque value, to track the target torque curve changing with angle with high precision; During the whole process of landing gear retraction movement, the angle acquisition, target value calculation and torque closed loop tracking steps are executed cyclically, and safety monitoring is continuously carried out.
8. The method for aerodynamic load simulation application for landing gear retraction test according to claim 7, characterized in that, In the system initialization step, torque safety working upper and lower limits, PID control parameters and the gentle rising time of open loop loading are also set.
9. The method for simulating application of aerodynamic load for landing gear retraction test according to claim 7, characterized in that, After the angle is acquired in real time and the target torque value is calculated, a step of limiting the target torque value is further included, and if the target torque value exceeds a safety boundary, it is limited within a safety value range.
10. The method for aerodynamic load simulation application for landing gear retraction test according to claim 7, characterized in that, The open-loop control mode starting step specifically includes: the control and processing unit (1) outputs an analog voltage signal starting from zero and linearly increasing to the target torque value within a preset time to the loading motor (6) driver.