Moving body stall self-driven warning unit, warning method and auxiliary design method

Abstract

The present invention provides a self-driven early warning unit and method for stalling a moving body. The early warning unit comprises: a triboelectric sensing unit comprising a triboelectric layer and a triboelectric layer attached to the surface of the moving body to be sensed. One end of the triboelectric layer is fixed to the triboelectric layer. When the moving body is not stalled, the other end engages the triboelectric layer in a contact-separation manner to generate a continuous triboelectric signal. When the moving body stalls, the frequency or voltage of the triboelectric signal decreases or disappears. The triboelectric signal is used to determine whether the moving body has stalled. And / or a piezoelectric sensing unit having a sheet-like structure attached to the triboelectric layer. When the moving body stalls, different piezoelectric signals are generated depending on the bending angle of the triboelectric layer. The piezoelectric signals are used to determine the degree of stall of the moving body. Accordingly, an auxiliary design method for moving body components and turbulence generators is also provided. The early warning unit has a simple structure, low cost, and excellent reproducibility.

Description

Technical Field

[0001] The present invention relates to the field of motion body stall sensing, and in particular to a motion body stall self-driven early warning unit, an early warning system, an early warning method and an auxiliary design method. Background Art

[0002] The stall warning system of an existing aircraft specifically refers to a device that warns the pilot or ground operator when the aircraft is approaching a stall due to changes in the angle of attack. It consists of an angle of attack sensor, a Mach sensor, a flap position sensor, a stall warning controller, and an alarm device. The angle of attack sensor measures the instantaneous angle of attack of the aircraft, and the signal is input into the stall warning controller for comparison with the preset value of the stall warning angle of attack. This preset value is related to the Mach number and the flap position. When the instantaneous angle of attack of the aircraft is greater than the stall warning angle of attack, the alarm device is connected to send a warning signal to the pilot or ground operator. Although the device has excellent accuracy, it has the disadvantage of being expensive and complex. In addition, it is difficult to install an expensive stall warning system during the experimental design phase of the aircraft to reduce the high cost of the design phase.

[0003] At the same time, in addition to manned aircraft, the unmanned aircraft market is expanding. However, due to cost factors, drones cannot be equipped with the stall warning system of manned aircraft, which has a great impact on the flight safety of drones. Summary of the Invention

[0004] To overcome the problems of existing stall warning technology, the present invention adopts a technology that combines the triboelectric signal of a triboelectric nanogenerator (TENG) with the piezoelectric signal. The triboelectric signal or triboelectric-piezoelectric signal is used to self-drive the early warning of the stall process of a moving body such as an aircraft (manned or unmanned) and self-drive the warning after the stall is corrected.

[0005] The present invention provides a self-driving warning unit for stalling a moving object, comprising:

[0006] A triboelectric sensing unit comprises a triboelectric layer and a triboelectric layer, wherein the triboelectric layer is a flexible layer attached to the surface of the moving body to be sensed; the triboelectric layer is an elastic structure, one end of the triboelectric layer is fixed to the triboelectric layer, and when the moving body is not stalled, the other end of the triboelectric layer is in contact and separation with the triboelectric layer to generate a continuous triboelectric signal; when the moving body stalls, the frequency or voltage of the triboelectric signal decreases or disappears; the triboelectric signal is used to determine whether the moving body is stalled; and / or,

[0007] The piezoelectric sensing unit is a sheet-like structure attached to the triboelectric layer. When the moving object stalls, different piezoelectric signals are generated according to the bending angle of the triboelectric layer. These piezoelectric signals are used to determine the degree of stall of the moving object. The aforementioned early warning system is formed by an array of multiple early warning units.

[0008] Correspondingly, the present invention also provides a self-driven stall warning method, which adopts the above-mentioned warning unit or stall warning system, and the friction electric sensing unit generates a continuous friction electric signal to judge that the moving body is not in a stalled state; the frequency of the friction electric signal decreases or disappears, warning the moving body of stall; and / or, the piezoelectric sensing unit generates a piezoelectric signal at different bending angles of the friction electrifying layer to judge the degree of stall of the moving body.

[0009] Compared with the prior art, the technology of the present invention has the following advantages:

[0010] The warning unit and warning method of the present invention utilize the reverse airflow generated by gas separation at the rear end of the wing when a moving object such as an aircraft (manned fixed-wing and unmanned aerial vehicle) stalls to accurately perform stall warning and cancel the warning after the stall.

[0011] The triboelectric signal is used to accurately measure the gas separation during stall, and the piezoelectric signal is used to accurately measure the stall degree after the gas separation stall.

[0012] The triboelectric-piezoelectric signal in the early warning method is used in conjunction with CFD simulation analysis to assist in optimizing the design of moving body components, such as fixed-wing designs during the flight design phase.

[0013] The triboelectric-piezoelectric signal in the early warning method is used together with CFD simulation analysis to assist in optimizing the vortex generator in the design stage.

[0014] The friction electrode layer of the friction sensing unit uses ultra-thin metal foil materials such as stickers to solve the problem of complex conformation with moving bodies such as aircraft surfaces, and uses flexible and lightweight triboelectric and piezoelectric signal test patches to solve the weight problem of the equipment.

[0015] At the same time, the present invention can utilize CFD wing model finite element simulation to add a digital stall warning system and warning method for replicable aircraft, and repeatedly modify and improve moving body components such as the airfoil, vortex generators and other devices of the aircraft wing during the design stage, eliminating the need to use the existing complex stall sensing system and greatly reducing flight research and development costs.

[0016] Compared with existing sensing devices, the early warning unit and system of the present invention have a simple structure, low cost, excellent reproducibility, and can more accurately fit a variety of complex wing surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 This is a structural diagram of the self-driving warning unit for stalling a moving object according to the present invention;

[0019] Figure 2 This is a working principle diagram of the moving body stall self-driving warning unit of the present invention;

[0020] Figure 3 These are the piezoelectric signal test results of the self-driving warning unit for stalling a moving object. DETAILED DESCRIPTION

[0021] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0022] Aircraft (or moving body) stall refers to the situation where the aircraft or wing is working at an angle of attack greater than the maximum lift angle of attack, which is characterized by airflow separation and control failure. When the lift generated by the aircraft when moving forward is less than the gravity on the aircraft, the aircraft will fall or crash, and a high angle of attack stall will occur. The reason for the stall of the aircraft is that the wing has airflow separation at a high angle of attack, such as Figure 2 As shown, when an aircraft exceeds a certain angle of attack (AOA), the airflow at the rear end of the aircraft no longer flows along the wing surface due to the separation effect, causing the aircraft's lift to suddenly and significantly drop. Simultaneously, a reverse reaction turbulence is generated at the rear end of the aircraft's wing. These reverse forces also reduce the aircraft's lift, causing a stall. The emergence of AOA monitoring, AOA limiting, and anti-spin (spiral) control technologies has brought flight control technology to an advanced level with improved controllability. However, the development of flight control technology cannot permanently resolve the stall problem. After all, flight is not an independent activity of the aircraft. Environmental and human factors remain the most critical factors affecting flight safety. The present invention combines triboelectric nano-generated signals with piezoelectric sensing signals. Utilizing triboelectric-piezoelectric signals, the invention provides a self-actuated early warning system for aircraft (manned or unmanned) stalling, and a self-actuated release of the warning system after the stall is corrected. The present invention is described in detail below using specific embodiments.

[0023] The moving body stall self-driving warning unit provided in this embodiment includes a triboelectric sensor unit and a piezoelectric sensor unit. The typical structure is shown in FIG. Figure 1The triboelectric sensing unit includes a triboelectric layer 3 and a triboelectric layer 2, wherein the triboelectric layer 3 is a flexible layer attached to the surface of the moving body 4 to be sensed; the triboelectric layer 3 is an elastic structure, and one end of the triboelectric layer 3 is fixed to the triboelectric layer 3. When the moving body 4 is not stalled, the other end of the triboelectric layer 3 is in contact and separation with the triboelectric layer 3 to generate a continuous triboelectric signal; when the moving body 4 stalls, the frequency or voltage of the triboelectric signal decreases or disappears; the triboelectric signal is related to whether the moving body is stalled and can be used to determine whether the moving body is stalled and the degree of stall. The piezoelectric sensing unit 1 is a sheet structure attached to the triboelectric layer 2. When the moving body 4 stalls, different piezoelectric signals are generated according to the different bending angles of the triboelectric layer 2. The piezoelectric signal is used to determine the degree of stall of the moving body 4.

[0024] The triboelectric sensing unit and the piezoelectric sensing unit together construct a flexible triboelectric-piezoelectric composite sensing unit.

[0025] The moving body stall self-driven warning unit of this embodiment may also include an alarm unit (not shown in the figure) for receiving the above-mentioned triboelectric signal and piezoelectric signal and judging the stall state, wherein when the triboelectric signal is a continuous signal, no stall occurs; when the voltage value or frequency of the triboelectric signal is lower than the set value, the alarm unit issues a stall warning; or, when the triboelectric signal disappears, the alarm unit issues a serious stall signal; or, when the piezoelectric signal appears, the alarm unit issues a complete stall signal.

[0026] The moving object to be sensed in this embodiment may be an aircraft, such as a fixed-wing aircraft or a drone, or may be a car, a ship, or a vessel.

[0027] Specifically, in this embodiment, the moving object 4 to be sensed is an aircraft. The triboelectric electrode layer 3 is a metal foil electrode, such as copper foil or gold foil, attached to the rear end of the aircraft (e.g., an airplane wing). The size of the triboelectric electrode layer 3 has no effect on the performance of the triboelectric sensing unit. To ensure a close fit with the surface of the moving object 4 to be sensed, such as an aircraft wing, the thickness can range from 0.01 mm to 0.5 mm. The metal copper foil electrode can be 1.5 cm wide by 10 cm long, ensuring close conformity to the aircraft surface.

[0028] The friction electrode layer 3 serves as both a contact layer with the friction electrification layer and a conductive layer in the friction electric sensing unit. The copper foil is 100 microns thick, 10 cm long and 1 cm wide, and is connected to the aircraft wing with 3M high-viscosity glue.

[0029] The triboelectric layer 2 has an elastic structure and can contact and separate with the triboelectrode layer 3 under the turbulence of the aircraft tail to generate triboelectric signals. The triboelectric layer 2 can be made of a polymer film, such as a FEP (Fluorinated ethylene propylene) polymer film with a length and width of 10 cm and 1 cm. One end of the triboelectric layer 2 ( Figure 1 The left side of the middle part) is connected to the left side head of the friction electrode layer 3 through 3M double-sided tape (1mm thickness), and the other end ( Figure 1 The left side of the center section is a free end, free to strike the triboelectrode layer 3. The driving force is the surface turbulence during flight. The triboelectric layer 2 and triboelectrode layer 3 engage in a contact-and-separate beating motion, generating a continuous triboelectric signal while the aircraft is not stalled.

[0030] The triboelectric layer of this embodiment can also be a triboelectric dielectric layer of a flexible triboelectric nanogenerator TENG with excellent performance, such as polymers such as PDMS (polydimethylsiloxane), PU (polyurethane), PET (polyethylene terephthalate), PI (polyimide) film, cellulose film and other materials.

[0031] The electrodes connected to the friction electrode layer 3 may include metal electrodes, carbon-based electrodes, polymer conductive electrodes, nanowire electrodes, and the like.

[0032] It can be seen from the working principle of the warning unit in the above embodiment that the triboelectric signal generated by the triboelectric sensing unit and the piezoelectric signal of the piezoelectric sensing unit can independently reflect the stall state of the moving body. Therefore, in other embodiments, the stall self-driven warning unit may only include the above-mentioned triboelectric sensing unit, or only include the above-mentioned piezoelectric sensing unit.

[0033] The piezoelectric sensing unit 1 is a sheet structure, which can be a stacked structure of a piezoelectric material patch and a conductive electrode. For example, the piezoelectric material patch uses a commercial PVDF piezoelectric film with a thickness of 100 microns, and the conductive electrode is a silver electrode deposited by magnetron sputtering with a thickness of 28 microns and a length and width of 5 cm and 1 cm. In order to better sense the bending degree of the triboelectric layer 2, the piezoelectric patch is attached to the triboelectric electrode layer 2 near the fixed end ( Figure 1 At 5 cm from the center left side of the aircraft, the severity of the aircraft stall can be judged by the piezoelectric signals at different bending angles after the aircraft stalls.

[0034] Combine Figures 1 to 3By constructing a complete and reproducible stall warning unit, the triboelectric signal sensing data of stage A can be obtained. Through the analysis of the triboelectric signal sensing data, after the reverse gas separation force is generated at the rear end of the moving body such as the aircraft wing, the flapping frequency of the triboelectric layer will gradually decrease. When it decreases to a certain level (such as after the AC voltage amplitude of the triboelectric signal drops to the ±1V range), it begins to bend in the opposite direction. At this time, the triboelectric signal disappears. When the flapping frequency of the triboelectric layer 2 gradually decreases, a stall warning can be issued. When the triboelectric signal disappears, a serious stall signal can be issued. When the triboelectric layer begins to bend in the opposite direction and the piezoelectric unit starts to work and generate piezoelectric signals, a complete stall signal can be issued. If the stall cannot be corrected at this time, it will have a great impact on the safety of the aircraft.

[0035] The present invention adopts a technology that combines friction nano-power generation signals with piezoelectric sensing signals. The triboelectric-piezoelectric signal is used to perform self-driven early warning of the stall process of the aircraft (manned or unmanned). It can help the pilot or controller correct the stall and self-drive to cancel the warning after the stall is corrected. At this time, the triboelectric signal is restored, allowing the aircraft to fly normally again.

[0036] The triboelectric sensor unit, the piezoelectric sensor unit and the alarm unit form a replicable digital stall warning system for aircraft.

[0037] In another embodiment of the present invention, a method for early warning of stall of a moving object is provided. Figure 2 , using the digital stall warning system provided in the above embodiment, the moving body 4 to be sensed is an aircraft, and the triboelectrode layer 3 is a metal foil electrode, which performs contact and separation tapping with the triboelectric layer 2 to generate a continuous triboelectric signal, and judges that the aircraft is not in a stalled state. The piezoelectric material patch of the piezoelectric sensing unit 1 can judge the severity of the aircraft stall through the piezoelectric signals at different bending angles after the stall. The triboelectric-piezoelectric composite sensing signal can be used to accurately sense and warn the aircraft stall. The process can be divided into two stages. In stage A ( Figure 2 Indicated by the arrow in the middle): The triboelectric layer 2 generates triboelectric signals due to the weak turbulence beating the triboelectrode layer 3 up and down in the non-stall state. Figure 2 (As shown by the middle arrow): The elastic triboelectric layer 2 bends upward in the stall state, and the triboelectric signal decreases in frequency to disappear, which can warn of the stall. In this embodiment, when the triboelectric signal drops to within the range of ±1V, a stall warning begins. After the stall, the degree of bending is sensed by the piezoelectric material patch, and the piezoelectricity indicates the severity of the stall. In this embodiment, when the piezoelectric signal is generated, the stall occurs, and when the piezoelectric signal is greater than the set value, such as 4V, it is determined to be a severe stall.

[0038] At the same time, in other embodiments, the above-mentioned warning units can be arrayed, and multiple warning units can be arranged in an array on the surface of the aircraft (moving body), such as spreading triboelectric-piezoelectric composite self-driven warning units horizontally and vertically on the wing surface to build a complete digital stall warning system for replicable aircraft.

[0039] The present invention also provides an auxiliary design method for moving body parts (such as aircraft wings). In an aircraft testing environment, such as a wind tunnel, a continuous triboelectric signal is generated when the aircraft is not stalled. The severity of the aircraft stall can be judged through the piezoelectric signal after the stall; the design of the moving body parts is repeatedly modified based on the test results.

[0040] The present invention also provides an auxiliary design method for a vortex generator. Under a test environment, the vortex generator adopts the above-mentioned stall self-driven warning method to generate a continuous triboelectric signal when the vortex generator is not stalled. After the stall, the severity of the stall of the vortex generator is judged by the piezoelectric signal; the design of the vortex generator is repeatedly modified according to the test results.

[0041] The above-mentioned test environment may include atmospheric testing, wind tunnel testing, and the gas may include air, oxygen, nitrogen, argon and the like.

[0042] The auxiliary design method of this embodiment can use triboelectric-piezoelectric composite sensing signals to accurately sense and warn aircraft stall, and perform auxiliary design of moving parts.

[0043] At the same time, the auxiliary design method of this embodiment can use arrayed multiple warning units to perform multi-channel warning, spread the triboelectric-piezoelectric composite warning units horizontally and vertically on the aircraft wing surface, and build a complete digital stall warning system for replicable aircraft.

[0044] At the same time, CFD wing model finite element simulation can be combined with the aforementioned auxiliary design method for reproducible moving body components, such as aircraft, and the aforementioned self-driven stall warning method to assist in the design of aircraft airfoils, vortex generators, and other devices during the design phase. This allows for repeated modification and improvement, eliminating the need for existing complex stall sensing systems and significantly reducing flight R&D costs. In this embodiment, the CFD simulation software is Ansys Fluent 2012.

[0045] In a specific example of this embodiment, a wing section of a model Cessna 182 aircraft is used as a test carrier, and the wing selected for CFD simulation and finite element simulation is also a Cessna 182 model. The wind tunnel is a professional-grade wind tunnel with a backflow neck that can generate a maximum wind speed of 80 m / s. The wind tunnel test section is 1 m long and 50 cm wide and high.

[0046] In this invention, the composite sensor signal of piezoelectric and triboelectric signals is measured using a Keithley 6514 meter. The open-circuit voltage signal is connected to the stall warning unit in the wind tunnel via ultra-fine wires. A specific test result is shown in the figure.

[0047] The auxiliary design method of this embodiment can be used for, but not limited to, aircraft stall warning, as well as automobile streamline design, and design optimization of various moving parts such as drones, aircraft, hulls, and ship bodies.

[0048] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner unless there is any contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. In addition, the various different embodiments of the present invention can also be combined in any manner, as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A self-driving warning unit for stalling a moving object, characterized in that: include: A triboelectric sensing unit comprises a triboelectric layer and a triboelectric layer, wherein the triboelectric layer is a flexible layer attached to the surface of the moving body to be sensed; The triboelectric layer is an elastic structure, one end of which is fixed to the triboelectrode layer. When the moving body is not stalled, the other end of the triboelectric layer is in contact and separation with the triboelectrode layer to generate a continuous triboelectric signal. When the moving body stalls, the frequency or voltage of the triboelectric signal decreases or disappears. The triboelectric signal is related to whether the moving body has stalled. and / or, The piezoelectric sensing unit is a sheet-like structure attached to the triboelectric layer. When the moving body stalls, different piezoelectric signals are generated according to the different bending angles of the triboelectric layer. The piezoelectric signals are used to judge the degree of stall of the moving body.

2. The early warning unit according to claim 1, characterized in that: It also includes an alarm unit for receiving the triboelectric signal and the piezoelectric signal and judging the stall state, wherein when the triboelectric signal is a continuous signal, no stall occurs; when the voltage value or frequency of the triboelectric signal is lower than a set value, a stall warning is issued; or when the triboelectric signal disappears, the alarm unit issues a serious stall signal; or when the piezoelectric signal appears, the alarm unit issues a complete stall signal.

3. The early warning unit according to claim 1, characterized in that: The friction electrode layer is a metal foil.

4. The early warning unit according to claim 3, characterized in that: The thickness of the friction electrode layer ranges from 0.01 mm to 0.5 mm.

5. The early warning unit according to any one of claims 1 to 4, characterized in that: The triboelectric layer is a polymer film.

6. The early warning unit according to claim 5, characterized in that: The polymer film is an FEP film, a PDMS film, a PU film, a PET film, a PI film or a cellulose film.

7. The early warning unit according to any one of claims 1 to 4, characterized in that: The moving object to be sensed is a car, an aircraft or a ship.

8. The early warning unit according to claim 7, characterized in that: The friction electrode layer is arranged on the surface of the rear end of the moving body.

9. A stall warning system, comprising the moving body stall self-driven warning unit according to any one of claims 1 to 8, wherein a plurality of the warning units are arranged in an array on the surface of the moving body.

10. A stall self-driving warning method, characterized in that: Using the warning unit described in any one of claims 1 to 8 or the stall warning system described in claim 9, the triboelectric sensing unit generates a continuous triboelectric signal to determine that the moving body is in a non-stalled state; the frequency of the triboelectric signal decreases or disappears, warning the moving body of stall; and / or the piezoelectric sensing unit generates piezoelectric signals at different bending angles of the triboelectric layer to determine the degree of stall of the moving body.

11. The early warning method according to claim 10, characterized in that: When the piezoelectric signal is generated, a warning stall occurs; Alternatively, when the piezoelectric signal exceeds a set voltage value, it is determined to be a severe stall.

12. The early warning method according to claim 11, characterized in that: The set voltage value is 4V.

13. The early warning method according to any one of claims 10 to 12, characterized in that: When the voltage of the friction electric signal is lower than the set voltage value, a warning stall occurs.

14. The early warning method according to claim 13, characterized in that: The set voltage value is 1V.

15. The early warning method according to claim 10, characterized in that: The method further includes the following steps: after the moving body corrects the stall, the moving body self-drives and releases the warning.

16. An auxiliary design method for moving body parts, characterized in that: The moving body component, under a test environment, uses the stall self-driving warning method according to any one of claims 10 to 15 to generate a continuous triboelectric signal when the moving body component is not stalled, and determines the severity of the aircraft stall through the piezoelectric signal after the stall; The design of the moving body components is repeatedly modified based on the test results.

17. The auxiliary design method according to claim 16, characterized in that: The moving object is a car, an aircraft or a ship.

18. An auxiliary design method for a vortex generator, characterized in that: The vortex generator, under a test environment, uses the stall self-driving warning method according to any one of claims 10 to 15 to generate a continuous triboelectric signal when the vortex generator is not stalled, and judges the severity of the stall of the vortex generator by the piezoelectric signal after the stall; The design of the vortex generator was repeatedly modified based on the test results.

19. The auxiliary design method according to claim 16 or 18, characterized in that: It comprises a plurality of early warning units as described in claims 1-8, and the plurality of early warning units are arranged in an array.

20. The auxiliary design method according to claim 16 or 18, characterized in that: The test environment is an atmospheric test or a wind tunnel test, and the gases used include air, oxygen, nitrogen or argon.

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