Multi-dimensional deformation self-sensing framework based on flexible sensor and method thereof

Abstract

The application discloses a multi-dimensional deformation self-sensing framework based on a flexible sensor and a method thereof. The multi-dimensional deformation framework mainly comprises a connecting beam, an extensible beam, a sensor connecting piece, a flexible sensor and a rotary driving mechanism. The connecting beam and the extensible beam are connected through a thrust bearing, an electric push rod in the middle of the extensible beam can be elongated, and an output shaft of the rotary driving mechanism can drive the extensible beam to rotate relative to the connecting beam, so that the framework can realize multi-dimensional deformation of elongation and deflection simultaneously. The application further provides a deformation sensing method of the framework: the change of the length of the flexible sensor can change the received electric signal, and the length of the flexible sensor can be identified according to the change of the electric signal. The application connects two flexible sensors at diagonal positions on the upper and lower surfaces of the multi-dimensional deformation framework, changes the electric signal of the flexible sensor through deformation of the framework, identifies the deformation state of the framework, and forms a self-sensing system for the multi-dimensional deformation framework.

Description

Technical Field

[0001] This invention relates to the field of wing deployment and sweep-back sensing and recognition, and specifically to a multidimensional deformation self-sensing framework and method based on flexible sensors. Background Technology

[0002] Variant aircraft represent a significant development direction for next-generation aircraft. By altering their wing shape, variator aircraft can adapt to various flight conditions, thereby enhancing overall aerodynamic performance. Large sweep angles and low aspect ratios reduce drag, delay shock waves, and optimize high-speed flight performance; conversely, small sweep angles and high aspect ratios increase lift, improve maneuverability, and optimize low-speed flight performance. Among the many variability forms, variable sweep angle and variable aspect ratio are crucial. Currently, the detection of aircraft deformation states primarily relies on encoders, cable-stayed sensors, and optical encoders. While these methods offer high measurement accuracy, they are relatively heavy and bulky, difficult to integrate with other structures, and susceptible to electromagnetic interference. Flexible sensors, on the other hand, possess advantages such as lightweight structure, ease of integration with other structures, resistance to electromagnetic interference, and distributed sensing capabilities. They can provide a lightweight and compact solution for sensing next-generation supersonic variator mechanisms. Summary of the Invention

[0003] To enable morphing aircraft to simultaneously change sweep angle and span, and to address the issues of bulkiness and susceptibility to interference associated with traditional sensors such as encoders, drawstring sensors, and grating rulers, this invention provides a design and recognition method for a multidimensional deformable self-sensing frame based on a flexible sensor. This invention designs a multidimensional deformable frame and obtains the real-time length data of the flexible sensor by analyzing changes in the output electrical signal of the flexible sensor using an LSSVM model. The real-time deformation state of the multidimensional deformable frame is then derived through formula derivation.

[0004] The specific technical solution adopted in this invention is as follows:

[0005] In a first aspect, the present invention provides a multidimensional deformable self-sensing frame based on a flexible sensor, which includes a four-bar frame, a flexible sensor and a rotation drive mechanism.

[0006] The four-bar linkage is formed by connecting two connecting beams and two telescopic beams end to end, and each telescopic beam is connected to the two telescopic beams at both ends by a rotating connector. Sensor connectors are provided at the four corners of the four-bar linkage, and two flexible sensors are arranged in a staggered manner along the diagonal direction based on the four sensor connectors. The two flexible sensors are spatially staggered so as not to interfere with each other.

[0007] The rotary drive mechanism is installed at one of the corner points of the four-bar linkage, and its output shaft and the rotary connector at the corner point form a transmission engagement to change the relative angle between the connecting beam and the telescopic beam connected by the rotary connector.

[0008] The telescopic beam has controlled telescopic capability, and the four-bar linkage is driven to deform by the synchronous telescopic extension and contraction of the two telescopic beams.

[0009] The flexible sensor includes a sensor body and spring connectors coaxially arranged at both ends of the sensor body. The sensor body can output an electrical signal that is positively correlated with the tension it receives. One end of the spring connector is fixedly connected to the sensor body, and the other end is rotatably connected to the assembled rotary connector.

[0010] As a preferred embodiment of the first aspect above, the rotary connector includes a first connector assembled at the end of the connecting beam and a second connector assembled at the end of the telescopic beam;

[0011] The first connector includes a pair of thrust bearings detachably mounted at the ends of the connecting beam;

[0012] The second connector has symmetrical bearing countersunk holes on its top and bottom surfaces, and a central shaft is installed through the bearing countersunk holes on both sides. The central shaft is fixedly connected to the second connector and cannot rotate relative to it.

[0013] The two thrust bearings of the first connector are respectively assembled in the bearing countersunk holes on both sides of the second connector, the central shaft is assembled in the shaft holes of the two thrust bearings, and one end of one of the central shafts is rigidly connected to the output shaft of the rotary drive mechanism.

[0014] The torque output by the rotary drive mechanism is transmitted to the telescopic beam through the connected central shaft. The connecting beam remains stationary, while the telescopic beam rotates relative to the load under the action of the torque.

[0015] As a preferred embodiment of the first aspect, the telescopic beam is provided with an electric push rod, and the two ends of the electric push rod are respectively equipped with the second connecting member, so that the controlled telescopic beam can be extended and retracted by the electric push rod.

[0016] As a preferred embodiment of the first aspect, the first connector is detachably assembled on the connecting beam, and the second connector is detachably assembled on the telescopic beam.

[0017] As a preferred embodiment of the first aspect above, the flexible sensor includes a threaded ring, a spring, a washer, a silicone sleeve, a polymer spiral-wound sensor, and a fixing nut; the polymer spiral-wound sensor is embedded in the silicone sleeve, and the two sides of the silicone sleeve are connected to one end of the spring through the washer, while the other end of the spring is connected to the threaded ring.

[0018] As a preferred embodiment of the first aspect, the polymer spiral-wound sensor is made by first twisting carbon black nylon conductive fibers to form a fiber orientation angle inside the fibers, then winding them around an axis, and finally heat-treating and annealing them at a constant temperature of 170~190 ℃.

[0019] As a preferred embodiment of the first aspect above, the material of the silicone sleeve is liquid silicone with a Shore A hardness of 14 to 16 after curing.

[0020] As a preferred embodiment of the first aspect above, the rotary drive mechanism employs a servo motor.

[0021] In a second aspect, the present invention provides a method for identifying the deflection angle and elongation rate of a multidimensional deformable self-sensing frame, which is implemented using a multidimensional deformable self-sensing frame based on a flexible sensor as described in any of the first aspects above. The identification method includes:

[0022] During the operation of the multidimensional deformable self-sensing framework, the electrical signals output by each flexible sensor are sampled and recorded in real time. Then, the electrical signal data within the latest time window is extracted as the input electrical signal. The rate of change of the signal at adjacent sampling times in the input electrical signals is calculated pairwise. The input electrical signal and the calculated rate of change of the signal are combined and then input into a pre-fitted least squares support vector machine (LSSVM) model to obtain the current length of each flexible sensor.

[0023] Based on the current lengths of the two flexible sensors and the original dimensional parameters of the four-bar linkage before deformation, the deflection angle and elongation of the four-bar linkage are calculated through geometric relationships.

[0024] As a preferred embodiment of the second aspect above, the time window includes 2 to 4 consecutive sampling times, and the kernel function in the least squares support vector machine model adopts a radial basis function.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] This invention connects two flexible sensors diagonally to the upper and lower surfaces of a multidimensional deformable frame. The deformation of the frame alters the electrical signals of the flexible sensors, allowing the frame's deformation state to be identified, thus forming a self-sensing system. The proposed multidimensional deformable frame can achieve a 50% elongation while simultaneously deflecting 45°, meaning that for an airfoil, it can simultaneously change sweep angle and span, adapting to various flight conditions and improving the overall aerodynamic efficiency of the aircraft. The frame beams are connected using thrust bearings, requiring only the bearing friction to overcome for multidimensional deformation, reducing power consumption and saving energy. The flexible sensors are made of polymer helical winding, which is lower in cost, smaller in size, and lighter than other sensors. Furthermore, it employs an LSSVM model for sensing and identification, resulting in high efficiency and stability. This compact design allows the flexible sensors to monitor the deformation state of the multidimensional deformable frame in real time, contributing to the improved compactness of the aircraft's deformable structure. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the multidimensional deformation self-sensing framework based on flexible sensors of the present invention.

[0028] Figure 2 This is an exploded view of the connecting beam of the multidimensional deformable self-sensing frame based on a flexible sensor according to the present invention.

[0029] Figure 3 This is an exploded view of the telescopic beam of the multidimensional deformable self-sensing frame based on a flexible sensor according to the present invention.

[0030] Figure 4 This is a part drawing of the first and second beam connectors of the multidimensional deformable self-sensing frame based on a flexible sensor according to the present invention.

[0031] Figure 5 This is a schematic diagram of the flexible sensor structure of the multidimensional deformable self-sensing frame based on the flexible sensor of the present invention.

[0032] Figure 6 This is a flowchart of the sensor fabrication process of the multidimensional deformable self-sensing frame based on a flexible sensor according to the present invention.

[0033] Figure 7 This is a flowchart of the identification method of the multidimensional deformation self-sensing frame based on flexible sensors according to the present invention.

[0034] Figure 8 This is a schematic diagram of the deflection state of the multidimensional deformable self-sensing frame based on a flexible sensor according to the present invention.

[0035] Figure 9 This is a schematic diagram of the elongation state of the multidimensional deformation self-sensing frame based on a flexible sensor according to the present invention.

[0036] Figure 10 This is a schematic diagram of the synchronous elongation and deflection state of the multidimensional deformation self-sensing frame based on a flexible sensor according to the present invention.

[0037] Figure 11 This is a prediction result diagram of the multidimensional deformation self-sensing framework and its recognition method based on flexible sensors according to the present invention.

[0038] In the diagram, the components are: connecting beam 1, main beam 1-1, beam block fixing screw 1-2, thrust bearing 1-3, cover block 1-4, beam block fixing nut 1-5, telescopic beam 2, first beam connector 2-1, member rod fixing screw 2-2, electric push rod 2-3, second beam connector 2-4, member rod fixing nut 2-5, sensor connector 3, flexible sensor 4, threaded ring 4-1, spring 4-2, washer 4-3, silicone sleeve 4-4, polymer spiral wound sensor 4-5, fixing nut 4-6, and servo motor 5. Detailed Implementation

[0039] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the present invention can be combined accordingly without mutual conflict.

[0040] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0041] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0042] like Figure 1As shown, in a preferred embodiment of the present invention, a multidimensional deformable self-sensing frame based on flexible sensors is provided. The frame comprises a four-bar linkage, flexible sensors 4, and a rotary drive mechanism 5. The four-bar linkage is formed by two connecting beams 1 and two telescopic beams 2 connected end-to-end. The two connecting beams 1 are arranged at one set of opposite sides of the four-bar linkage, and the two telescopic beams 2 are arranged at the other set of opposite sides. Each telescopic beam 2 has two ends connected to the other two telescopic beams 2 via rotary connectors. Sensor connectors 3 are provided at the four corners of the four-bar linkage, and two staggered flexible sensors 4 are arranged diagonally based on the four sensor connectors 3. To ensure that the two flexible sensors 4 do not interfere with each other, they need to be spatially offset along the height direction, i.e., perpendicular to the plane of the four-bar linkage.

[0043] In the aforementioned four-bar linkage, the length of connecting beam 1 remains fixed, while the telescopic beam 2 should have controlled telescopic capability, so that the four-bar linkage is deformed by the synchronous telescopic movement of the two telescopic beams 2. It should be noted that although the two telescopic beams 2 in the four-bar linkage can be driven independently, in order to ensure the smoothness of the overall deformation, the telescopic amplitude of the two should be consistent.

[0044] Furthermore, the aforementioned rotary drive mechanism 5 is installed at one corner of the four-bar linkage frame. Its output shaft and the rotary connector at that corner form a transmission connection, used to change the relative angle between the connecting beam 1 and the telescopic beam 2 connected by the rotary connector. The form of the rotary drive mechanism 5 is not limited, as long as it can output rotational torque with high precision. In the embodiments of the present invention, the rotary drive mechanism 5 can be implemented using a servo motor.

[0045] Therefore, the structural forms of the connecting beam 1, the telescopic beam 2, and the rotating connectors at the ends of the four-bar linkage can be designed according to actual needs, as long as the two beams can cooperate with the specific rotating connectors at their ends to achieve the corresponding rotational drive function. In the embodiment of the present invention, the rotating connector includes a first connector mounted on the end of the connecting beam 1 and a second connector mounted on the end of the telescopic beam 2; the first connector includes a pair of detachable thrust bearings 1-3 mounted on the end of the connecting beam 1; the second connector has symmetrically provided bearing countersunk holes on its top and bottom surfaces, and a central shaft is installed through the bearing countersunk holes on both sides, the central shaft being fixedly connected to the second connector and unable to rotate relative to it. The two thrust bearings 1-3 of the first connector are respectively mounted in the bearing countersunk holes on both sides of the second connector, while the central shaft is mounted in the shaft holes of the two thrust bearings 1-3, and one end of a central shaft at one corner of the frame is rigidly connected to the output shaft of the rotating drive mechanism 5. The torque output by the rotary drive mechanism 5 is transmitted to the telescopic beam 2 through the connected central shaft. In the driving state, the connecting beam 1 remains stationary, while the telescopic beam 2 rotates relative to the torque, thereby causing the entire four-bar linkage to deform.

[0046] It should be noted that the above description of the structure and assembly form of the first and second connecting parts only reflects their key mechanisms. However, in the actual design of the corresponding mechanical structure, the assembly and detachable connection of all key mechanisms can be achieved through a series of auxiliary components.

[0047] To facilitate disassembly and maintenance, in this embodiment of the invention, the first connecting member is detachably assembled on the connecting beam 1, and the second connecting member is also detachably assembled on the telescopic beam 2. Specifically, as follows... Figure 2 As shown, in an embodiment of the present invention, the connecting beam 1 consists of a main beam 1-1, beam block fixing screws 1-2, a thrust bearing 1-3, a cover block 1-4, and beam block fixing nuts 1-5. Figure 3 As shown, the telescopic beam 2 is equipped with an electric push rod 2-3. The two ends of the electric push rod 2-3 are respectively equipped with the aforementioned second connecting parts. The controlled telescopic beam 2 is realized by the electric push rod 2-3. Thus, the telescopic beam 2 is composed of a first beam connecting part 2-1, a rod fixing screw 2-2, an electric push rod 2-3, a second beam connecting part 2-4, and a rod fixing nut 2-5.

[0048] The main beam 1-1 of the connecting beam 1 has a two-stage stepped platform structure on both its left and right sides. The cover blocks 1-4 on both sides are connected to the upper platform of the stepped platform structure on both sides of the main beam 1-1 via paired beam block fixing screws 1-2 and beam block fixing nuts 1-5. The lower platform of the stepped platform structure and the bottom surface of the cover blocks 1-4 are respectively provided with bearing countersunk holes that mate with thrust bearings 1-3. At each end of the main beam 1-1, two thrust bearings 1-3 can be assembled into two bearing countersunk holes, forming a rotary support structure for connecting the first beam connector 2-1 and the second beam connector 2-4. Furthermore, since the joint shapes of the motor end and displacement output end of the electric push rod 2-3 are different, the two second connectors assembled at both ends of the electric push rod 2-3 need to use first beam connectors 2-1 and second beam connectors 2-4 with different mounting groove shapes, such as... Figure 4 As shown. The first beam connector 2-1 can be assembled and connected to the motor end of the electric push rod 2-3 using a pair of rod fixing screws 2-2 and rod fixing nuts 2-5, while the second beam connector 2-4 can be assembled and connected to the displacement output end of the electric push rod 2-3 using a pair of rod fixing screws 2-2 and rod fixing nuts 2-5. Both the first beam connector 2-1 and the second beam connector 2-4 are rectangular assembly blocks. The top and bottom surfaces of the assembly blocks are respectively provided with bearing countersunk holes that match the thrust bearing 1-3. A central shaft is installed through the bearing countersunk holes on both sides. The mounting side of the assembly block has mounting holes that match the shape and size of the motor end and the displacement output end of the electric push rod 2-3. After the end of the electric push rod 2-3 is inserted into the corresponding mounting holes, it is then connected and fixed using rod fixing screws 2-2 and rod fixing nuts 2-5, which serves to change the length. The output shaft of the servo motor 5 is rigidly connected to the central shaft of the first beam connector 2-1, thereby transmitting the output torque to the central shaft. The central shaft then drives the assembly block and the electric push rod 2-3 to twist. Since there are thrust bearings 1-3 on both the top and bottom of the assembly block, its torsional force is not transmitted to the main beam 1-1. Therefore, when the servo motor 5 outputs torque, the connecting beam 1 remains stationary, while the telescopic beam 2 rotates, thus controlling the deflection angle of the four-bar linkage.

[0049] In the embodiments of the present invention, the connecting beam 1 and the telescopic beam 2 are connected by a thrust bearing 1-3. The electric push rod 2-3 in the middle of the telescopic beam can be extended by 50%. Therefore, the frame can achieve multi-dimensional deformation of 50% extension and 45° deflection.

[0050] To detect the rotational attitude parameters of the aforementioned four-bar linkage, two flexible sensors 4 are provided in this invention. Each flexible sensor 4 includes a sensor body and spring connectors coaxially arranged at both ends of the sensor body. The sensor body can output an electrical signal positively correlated with the tension it receives. One end of the spring connector is fixedly connected to the sensor body, and the other end is rotatably connected to the assembled sensor connector 3. For the four corner positions of the four-bar linkage, one set of diagonally opposite sensor connectors 3 can be installed on the top surface of the cover block 1-4, and the other set of diagonally opposite sensor connectors 3 can be installed on the bottom surface of the stepped platform structure of the main beam 1-1, thereby ensuring that the two flexible sensors 4 are staggered in the height direction and will not interfere. The sensor connector 3 consists of a connecting plate and a fixed shaft vertically mounted on the connecting plate. The connecting plate can be fixed to the top surface of the cover block 1-4 or the bottom surface of the stepped platform structure by means of adhesive or screws. The fixed shaft is used to connect the spring connectors of the flexible sensors 4.

[0051] In embodiments of the present invention, such as Figure 5 As shown, the flexible sensor 4 comprises a threaded ring 4-1, a spring 4-2, a washer 4-3, a silicone sleeve 4-4, a polymer spiral-wound sensor 4-5, and a fixing nut 4-6. The silicone sleeve 4-4 and the polymer spiral-wound sensor 4-5 constitute the aforementioned sensor body, while the remaining components constitute the aforementioned spring connector. The polymer spiral-wound sensor 4-5 is embedded within the silicone sleeve 4-4. Both ends of the silicone sleeve 4-4 are connected to one end of the spring 4-2 on their respective sides via the washer 4-3. The other end of the spring 4-2 is connected to the threaded ring 4-1. The spring 4-2 and the threaded ring 4-1 can be rigidly connected by welding or other auxiliary connectors. In this embodiment, the other end of the spring 4-2 can be fixedly connected to a washer. A hole is then drilled in the washer. The threaded ring 4-1 is composed of a ring body and an externally threaded rod. The externally threaded rod passes through the hole in the washer and is tightened onto the washer by a fixing nut 4-6, thus achieving the connection and assembly of the spring 4-2 and the threaded ring 4-1. Silicone sealant can be used to connect the silicone sleeve 4-4 and the washer 4-3, as well as the spring 4-2 and the washer 4-3.

[0052] Furthermore, to facilitate the rotational connection between the threaded rings 4-1 at both ends of the flexible sensor 4 and the assembled sensor connector 3, the outer diameter of the fixed shaft of the sensor connector 3 must be smaller than the inner diameter of the threaded rings 4-1. This allows the threaded rings 4-1 at both ends of the flexible sensor 4 to fit onto the fixed shaft of the sensor connector 3 at the two connected corner points. This ensures that the flexible sensor 4 will not rotate with the fixed shaft, allowing it to only undergo axial expansion and contraction without bending. Additionally, to ensure the linearity of the sensor, the polymer spiral-wound sensor 4-5 and the springs 4-2 connected on both sides must remain coaxially arranged under tension.

[0053] In an embodiment of the present invention, a method for manufacturing the above-described flexible sensor 4 is also provided. For example... Figure 6 As shown, the polymer spiral-wound sensor 4-5 is made by twisting 0.65 mm diameter carbon black nylon conductive fibers to form a fiber orientation angle inside the fibers, then winding them around a shaft, and finally heat-treating them in a muffle furnace at a constant temperature of 180 ℃ for half an hour. After annealing and shaping, the polymer spiral-wound sensor 4-5 is completed. In this embodiment, the silicone sleeve 4-4 is made of liquid silicone with a cured Shore A hardness of 15. Therefore, based on the prepared polymer spiral-wound sensor 4-5, the process of further embedding it into the silicone sleeve 4-4 is as follows: First, fix the polymer spiral-wound sensor 4-5 around the mandrel, and insert the mandrel into a silicone mold with a cuboid inner cavity; take an appropriate amount of liquid silicone, add a curing agent and stir evenly, then place it in a vacuum defoaming machine to eliminate air bubbles. After defoaming, fill the inner cavity of the mold with silicone solution and cure for 4 hours; after complete curing, pull out the mandrel, and the polymer spiral-wound sensor 4-5 is embedded in the silicone sleeve 4-4, forming the finished product. Finally, spring connectors are further processed at both ends of the silicone sleeve 4-4 to form a complete flexible sensor 4.

[0054] The sensing method of the above-mentioned flexible sensor 4 is as follows: during the deformation of the four-bar frame, the change in the length of the flexible sensor 4 will cause the spring 4-2 to drive the silicone sleeve 4-4 and the polymer spiral wound sensor 4-5 to change their lengths; since the change in the length of the polymer spiral wound sensor 4-5 will cause the resistance of the carbon black nylon conductive fiber to change, the received electrical signal will change, and the length of the flexible sensor 4 can be derived from the change in the electrical signal.

[0055] Based on the above Figure 1 The aforementioned multidimensional deformable self-sensing frame based on flexible sensors, due to the connection of the beams using thrust bearings 1-3, allows the frame to achieve both elongation and large-angle deflection. For example... Figure 7The diagram shown is a flow chart of the sensing process of the flexible sensor 4. If, in the initial state, the lengths of the two connecting beams 1 and the two telescopic beams 2 in this frame are all... If the frame initially has a square orientation, then during the deformation process, the length of the first flexible sensor 4 on the upper surface of the frame changes by a range of 1.41. ~2.32 The length variation range of the second flexible sensor 4 on the lower surface of the frame is 0.77 mm. ~1.8 mm. In an embodiment of the present invention, assuming that the lengths of the two connecting beams 1 and the two telescopic beams 2 are all 200 mm, and the maximum telescopic stroke of the telescopic beam 2 is 100 mm, then the frame can achieve an elongation of 50% while deflecting 45°. The length variation range of the first flexible sensor 4 on the upper surface of the frame is 282.84~463.52 mm, and the length variation range of the second flexible sensor 4 on the lower surface of the frame is 153.07~360.56 mm.

[0056] The change in the length of the flexible sensor 4 will cause a change in the resistance of the polymer spiral-wound sensor 4-5. Therefore, the Least Squares Support Vector Machine (LSSVM) model is used to obtain the relationship between the output electrical signal of the polymer spiral-wound sensor 4-5 and the length of the flexible sensor 4. The LSSVM model formula is as follows:

[0057]

[0058] In the formula, N is the total number of training data samples in the training dataset used to fit the LSSVM model. Let be the weight coefficient of the i-th training sample. The support vector of the i-th training sample For deviation; For the kernel function, the radial basis function (RBF) is used in this embodiment, and its expression is:

[0059]

[0060] In the formula This refers to kernel bandwidth parameters.

[0061] The current model input is represented by the electrical signal data within the latest time window. The rate of change of the input electrical signal is calculated pairwise between adjacent sampling times. The combination of the input electrical signal and the calculated rate of change is then used as the current model input. The size of the time window can be optimized according to actual needs, generally containing 2 to 4 consecutive sampling times. Taking a time window containing 4 consecutive sampling times as an example, the model input... The expression is:

[0062]

[0063] In the formula For the current moment The output electrical signal of the polymer spiral-wound sensor 4-5 obtained by sampling. Each represents the current time. The output electrical signals of the polymer spiral-wound sensor 4-5 were sampled at the first, second, and third sampling times. The period is the signal sampling period.

[0064] The present invention can obtain an LSSVM model by training and fitting the sampled data in advance, and then obtain the length of the flexible sensor 4 in real time by identifying the electrical signal output by the polymer spiral wound sensor 4-5. The deflection angle and elongation of the frame can be derived from the length of the flexible sensor 4.

[0065] In this invention, the deflection angle of the frame is defined as the complementary angle between the connecting beam 1 and the telescopic beam 2 directly driven by the rotary drive mechanism 5. Simultaneously, the elongation rate of the frame is defined as the ratio obtained by dividing the elongation of the telescopic beam 2 relative to its original length by its original length.

[0066] Assume that in the initial state, the lengths of the two connecting beams 1 and the two expansion beams 2 of the frame are all... The length of the first flexible sensor 4 in the deformed current frame, obtained through the LSSVM model, is... The length of the second flexible sensor 4 is Then the deflection angle of the frame and elongation It can be obtained through geometric conversion, and the conversion formula is:

[0067]

[0068]

[0069] Therefore, based on the aforementioned multidimensional deformation self-sensing framework, a method for identifying deflection angle and elongation can be designed in this invention, as follows:

[0070] During the operation of the multidimensional deformable self-sensing frame, the electrical signals output by each flexible sensor 4 are sampled and recorded in real time. Then, the electrical signal data within the latest time window is extracted as the input electrical signal. The rate of change of the signal at adjacent sampling times in the input electrical signals is calculated pairwise. The input electrical signals and the calculated rate of change of the signal are combined and input into a pre-fitted LSSVM model to obtain the current length of each flexible sensor 4. Then, based on the current length of the two flexible sensors 4 and the original size parameters of the four-bar frame before deformation, the deflection angle and elongation of the four-bar frame are calculated through geometric relationships.

[0071] Specifically, in an actual implementation process, the specific sensing process is as follows:

[0072] First, the flexible sensor 4 undergoes multiple stretching and shortening cycles, collecting its length and output electrical signal data to construct a training dataset. Each training data sample in the training dataset contains the model input... As shown in Equation 3, the measured length of the flexible sensor 4 is used as the output label value. The LSSVM model shown in Equation 1 is written in MATLAB, and its model parameters and kernel function (RBF is used here) are selected. The training dataset with a total sample size of N is imported into the LSSVM model for training, and the parameters are obtained. , , and Then, the LSSVM model is written into LabVIEW and the parameters determined during training are entered. , , and This serves as the LSSVM model used for actual state perception. After deployment, frame self-sensing testing can be performed. The flexible sensor 4 is assembled onto the four-bar frame connection. When the frame deforms, the output electrical signal data of the flexible sensor 4 is collected in real time and used as the model input. The length data of the two flexible sensors 4 are calculated by writing the data into the LSSVM model in LabVIEW. Substituting the obtained length data into formulas (4) and (5) yields the deflection angle of the frame. and elongation This enables the perception of the frame's deformation state.

[0073] like Figure 8 , Figure 9 and Figure 10 The diagram shown illustrates different states of a multidimensional deformable self-sensing framework design based on a flexible sensor and its recognition method. Figure 8 This diagram illustrates the state in which the multidimensional deformable self-sensing frame only deflects. Figure 9This diagram illustrates the state in which the multidimensional deformable self-sensing frame only elongates; and Figure 10 The diagram illustrates the simultaneous elongation and deflection of the multidimensional deformable self-sensing frame. Under different states, the resistance of the polymer spiral-wound sensor 4-5 corresponding to the flexible sensor 4 varies, resulting in different output electrical signals. This principle can be used for sensing and perception.

[0074] like Figure 11 As shown, to further verify the actual performance of the multidimensional deformable self-sensing framework and its recognition method based on flexible sensors of the present invention, an actual verification experiment was conducted on the framework. The final results of the actual deflection angle and the predicted deflection angle are as follows: Figure 11 As shown. By Figure 11 As can be seen, the experimental results are in good agreement with the predicted results, which verifies the reliability of the present invention in sensing the deformation state of the frame.

[0075] The multidimensional deformable self-sensing frame based on flexible sensors of the present invention can be used on aircraft wings to enable simultaneous changes in sweep angle and span, adapting to various flight conditions and improving the overall aerodynamic performance of the aircraft.

[0076] The embodiments described above are merely some preferred implementations of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A multi-dimensional deformation self-sensing frame based on a flexible sensor, characterized in that, The four-bar linkage frame, the flexible sensor (4) and the rotary drive mechanism (5); The four-bar linkage frame is formed by connecting two connecting beams (1) and two telescopic beams (2) at their ends, and the two ends of each telescopic beam (2) are respectively connected with the two telescopic beams (2) through rotary connectors; sensor connectors (3) are arranged at four corner positions of the four-bar linkage frame, and two flexible sensors (4) are arranged in a staggered manner along the diagonal direction based on the four sensor connectors (3), and the two flexible sensors (4) are staggered in space so as not to interfere with each other; The rotary drive mechanism (5) is installed at one of the corner positions of the four-bar linkage frame, and the output shaft of the rotary drive mechanism (5) is in transmission cooperation with the rotary connector at the corner position, which is used to change the relative angle between the connecting beam (1) and the telescopic beam (2) connected by the rotary connector; The telescopic beam (2) has a controlled telescopic ability, and the four-bar linkage frame is deformed by synchronous telescopic driving of the two telescopic beams (2); The flexible sensor (4) includes a sensor body and spring connectors coaxially arranged at both ends of the sensor body, the sensor body can output an electric signal positively correlated with the tension it receives, one end of the spring connector is fixedly connected with the sensor body, and the other end is in rotary connection with the assembled sensor connector (3).

2. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 1, wherein, The rotary connector includes a first connector assembled at the end of the connecting beam (1) and a second connector assembled at the end of the telescopic beam (2); The first connector includes a pair of thrust bearings (1-3) detachably mounted at the end of the connecting beam (1); The top surface and the bottom surface of the second connector are symmetrically provided with bearing counterbores, and a center shaft is installed through the bearing counterbores on both sides, and the center shaft is fixedly connected with the second connector and cannot rotate relative to the second connector; The two thrust bearings (1-3) of the first connector are respectively assembled in the bearing counterbores on both sides of the second connector, the center shaft is assembled in the shaft hole of the two thrust bearings (1-3), and one end of one of the center shafts is rigidly connected with the output shaft of the rotary drive mechanism (5); The torque output by the rotary drive mechanism (5) is transmitted to the telescopic beam (2) through the connected center shaft, the connecting beam (1) remains stationary, and the telescopic beam (2) rotates relative to the connecting beam (1) under the action of the torque.

3. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 2, wherein, The telescopic beam (2) is provided with an electric push rod (2-3), and the two ends of the electric push rod (2-3) are respectively assembled with the second connector, and the controlled telescopic ability of the telescopic beam (2) is realized by the electric push rod (2-3).

4. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 2, wherein, The first connector is detachably assembled on the connecting beam (1), and the second connector is detachably assembled on the telescopic beam (2).

5. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 1, wherein, The flexible sensor (4) comprises a threaded ring (4-1), a spring (4-2), a gasket (4-3), a silica gel sleeve (4-4), a polymer spiral winding type sensor (4-5) and a fixing nut (4-6); the polymer spiral winding type sensor (4-5) is embedded in the silica gel sleeve (4-4), the silica gel sleeve (4-4) is connected with one end of the spring (4-2) through the gasket (4-3) on both sides, and the other end of the spring (4-2) is connected with the threaded ring (4-1).

6. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 5, wherein, The polymer spiral winding type sensor (4-5) is made of carbon black nylon conductive fiber, which is twisted and twisted to form a fiber orientation angle in the fiber, then wound around the axis, and finally annealed and shaped at 170-190 ℃ constant temperature environment.

7. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 5, wherein, The material of the silica gel sleeve (4-4) is liquid silicone with a Shore A hardness of 14-16 degrees after curing.

8. The flexible sensor-based multi-dimensional morphing self-sensing frame of claim 1, wherein, The rotating drive mechanism (5) adopts a servo motor.

9. A multi-dimensional deformation self-sensing frame deflection angle and elongation rate identification method, characterized in that, The recognition method comprises: During the operation of the multi-dimensional deformation self-sensing frame, the electrical signals output by each flexible sensor (4) are sampled and recorded in real time, then the electrical signal data in the latest time window are extracted as input electrical signals, the signal change rates of adjacent sampling time points in the input electrical signals are calculated two by two, the input electrical signals and the calculated signal change rates are combined and input into a pre-fitted least squares support vector machine model to obtain the current length of each flexible sensor (4); According to the current lengths of the two flexible sensors (4) and the original size parameters of the four-bar linkage frame before deformation, the deflection angle and the elongation rate of the four-bar linkage frame are calculated through geometric relationship.

10. The multi-dimensional anisotropic self-sensing frame deflection angle and elongation ratio identification method of claim 9, wherein, The time window contains 2-4 continuous sampling time points, and the kernel function in the least squares support vector machine model adopts a radial basis function.

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