Space non-cooperative target variable stiffness racemization device based on dielectric elastomer and application of space non-cooperative target variable stiffness racemization device

Abstract

The invention relates to the technical field of space non-cooperative target capturing and racemization, in particular to a space non-cooperative target variable-stiffness racemization device based on a dielectric elastomer and application of the space non-cooperative target variable-stiffness racemization device, and the space non-cooperative target variable-stiffness racemization device is suitable for attitude control and racemization operation of space tumbling satellites, space debris and other non-cooperative targets. The supporting assembly comprises a middle shaft, a middle shaft servo motor and a fixing base, the middle shaft vertically penetrates through the fixing base, and the middle shaft servo motor is in transmission connection with the middle shaft and used for driving the middle shaft to rotate around the axis of the middle shaft or driving the middle shaft to pitch in the vertical direction so as to adjust the space posture of the arm rotation eliminating body. Compared with the prior art, the racemization device is high in racemization precision, good in operation flexibility, free of fuel consumption and suitable for long-term space tasks.

Description

Technical Field

[0001] This invention relates to the field of space non-cooperative target acquisition and despinning technology, specifically to a space non-cooperative target variable stiffness despinning device based on a dielectric elastomer and its application, applicable to attitude control and despinning operations of non-cooperative targets such as space tumbling satellites and space debris. Background Technology

[0002] With the development of the space industry, the number of non-cooperative targets in space (such as faulty tumbling satellites, abandoned rocket debris, and space debris) is constantly increasing. The unstable attitude of these targets (such as high-speed tumbling) poses a huge challenge to capture, repair, or removal missions. Despinning, as a key step in handling non-cooperative targets in space, aims to suppress the rotational motion of the target through external torque, thereby stabilizing the target's attitude.

[0003] Existing space despinning technologies are mainly divided into two categories: one is non-contact despinning, such as plume despinning technology, which uses a thruster to generate force to achieve despinning. However, this technology has problems such as high fuel consumption, low force control precision, and easy secondary pollution to the target, and is not suitable for long-term missions. The other is contact despinning, such as multi-stage deceleration rod despinning technology, which generates braking torque by contacting the target with a rigid or flexible rod. However, the stiffness of traditional contact despinning rods is fixed and cannot be dynamically adjusted according to the real-time rotation speed of the target. For high-speed tumbling targets, fixing low stiffness can easily lead to excessively long despinning time, while fixing high stiffness can easily generate excessive impact loads, damaging the target or despinning device. At the same time, the existing despinning rods generally have low degrees of freedom (mostly single-degree-of-freedom rotation), making it difficult to adapt to the complex attitude of space targets and resulting in poor operational flexibility.

[0004] Dielectric elastomers, as a type of intelligent flexible material, possess electric field-induced stiffness variation characteristics (after applying voltage, the internal polarization effect of the material changes, and the elastic modulus can be dynamically adjusted within the range of 1MPa to 100MPa). They also offer advantages such as light weight, fast response speed (millisecond level), noiselessness, and wear-free operation, making them highly promising for applications in space flexible actuators. Currently, there is no technical solution that combines the variable stiffness characteristics of dielectric elastomers with multi-degree-of-freedom arms for derotation of non-cooperative targets in space. Summary of the Invention

[0005] This invention addresses the shortcomings and deficiencies of existing technologies by proposing a variable stiffness despinning device for non-cooperative targets in space, based on a dielectric elastomer, and its application, which is suitable for attitude control and despinning operations of non-cooperative targets such as space-tumbling satellites and space debris.

[0006] This invention achieves its purpose through the following measures: A spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer, characterized in that it includes a support assembly comprising an intermediate shaft, an intermediate shaft servo motor, and a fixed base. The intermediate shaft vertically penetrates the fixed base, and the intermediate shaft servo motor is drively connected to the intermediate shaft for driving the intermediate shaft to rotate around its own axis or to tilt the intermediate shaft in the vertical direction to adjust the spatial attitude of the arm despinning body. Two symmetrically arranged despinning rod assemblies are respectively mounted on the intermediate shaft, wherein each despinning rod assembly includes an arm despinning body, an arm rotation motor, and a despinning contact body. The body has a strip-shaped anti-rotation rod shell. Inside the anti-rotation rod shell, there is a linear slide rail arranged along the length of the anti-rotation rod shell, and a slider that cooperates with the slide rail. The anti-rotation contact body is fixedly connected to the slider. The anti-rotation contact body includes a long strip-shaped shell connected to the slider. Inside the shell, there are two or more dielectric elastomers. The dielectric elastomers are connected to a battery and a control mechanism located at the rear end of the anti-rotation rod shell via wires. Inside the anti-rotation rod shell, there is also an arm-end drive motor and a gear connected to the output shaft of the arm-end drive motor. The outside of the anti-rotation contact body is provided with a rack that meshes with the gear. The rack extends along the length of the anti-rotation contact body. The dielectric elastomer is a multilayer composite structure, and its two electrical terminals are electrically connected to the control module through wires so that its stiffness can be adjusted by changing the applied voltage. The control mechanism is also electrically connected to the arm rotation motor, the arm end drive motor, and the dielectric elastomer, respectively, to receive the real-time rotation speed signal of the non-cooperative target in space, and output control commands to the shaft drive motor to adjust the posture of the derotating arm, to the arm end drive motor to control the rotation speed of the dielectric elastomer unit, and to the dielectric elastomer unit to adjust the applied voltage and thus change its stiffness.

[0007] The elongated shell of the anti-rotation contact body described in this invention is made of an elastic material, such as foam plastic, to improve the stiffness adjustment sensitivity of the anti-rotation contact body while supporting and fixing the rack. The anti-rotation rod shell is also equipped with a limit switch for detecting the extension length of the anti-rotation contact body 15. The anti-rotation contact body is equipped with a pressure sensor to collect pressure data when in contact with the target. A vision sensor connected to the control mechanism is also provided to collect data such as the target rotation speed.

[0008] The dielectric elastomer unit of the present invention includes an upper electrode layer, a dielectric elastomer base layer, and a lower electrode layer stacked sequentially; the dielectric elastomer base layer is made of silicon-based dielectric elastomer material; both the upper electrode layer and the lower electrode layer are flexible conductive films made of carbon nanotube / polyimide composite conductive material; in the multilayer composite structure of the dielectric elastomer, a flexible insulating isolation layer is provided between adjacent dielectric elastomer base layers, the isolation layer is made of polytetrafluoroethylene material with a thickness of 2μm~5μm, and is used to prevent interlayer breakdown.

[0009] Both sides of the anti-rotation contact body can be provided with racks that mesh with gears connected to the output end of the arm-end drive motor. The racks extend along the length direction of the anti-rotation contact body, and correspondingly, two sets of arm-end drive motors and gears are provided.

[0010] The intermediate shaft drive motor in this invention is a dual-degree-of-freedom servo motor, possessing rotational freedom (rotation angle range 0°~270°) around the intermediate shaft axis and pitch freedom (pitch angle range -30°~30°) along the vertical plane, and is equipped with a reduction mechanism with a reduction ratio of 1:50~1:100; the arm-end drive motor is a brushless DC servo motor with an output speed range of 0~1000rpm, equipped with a torque sensor, which can provide real-time feedback of the torque signal when the dielectric elastomer unit contacts a non-cooperative target in space to the control module.

[0011] In this invention, the control mechanism is located inside the satellite and includes a signal acquisition unit, a processor, and a drive unit. The signal acquisition unit is used to receive rotational speed detection signals (such as visual sensor or lidar signals) and feedback signals from torque sensors of non-cooperative targets in space. The processor adopts an FPGA+ARM architecture and is used to calculate the optimal stiffness adjustment voltage and motor speed based on the acquired signals. The drive unit includes a motor driver and a high-voltage power supply module. The motor driver is used to drive the shaft drive motor and the arm-end drive motor, and the high-voltage power supply module is used to provide an adjustable DC voltage of 0~5kV to the dielectric elastomer.

[0012] The arm despinning body 2 described in this invention is made of carbon fiber composite material, with a length of 0.5m to 1.5m, a hollow rectangular cross-section, and a wall thickness of 5mm to 10mm, in order to reduce weight and ensure structural strength.

[0013] The present invention also includes a buffer component, which is disposed at the connection between the arm despinning body 2 and the intermediate shaft, and is made of polyurethane elastic material to absorb the vibration generated by the target impact during the despinning process.

[0014] This invention also proposes an application of the spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer as described above, characterized by comprising the following steps: Step 1: Initialization and Attitude Alignment Phase: When the service satellite approaches the target satellite to a distance of 50m, the visual sensor is activated, acquires the three-dimensional attitude of the target satellite, and transmits it to the anti-rotation rod control mechanism via RS485 bus. The control mechanism then performs initialization. Step 2: Arm extension and retraction phase: The control mechanism calculates the optimal extension amount of the dual-arm de-rotation body based on the diameter of the target satellite, ensuring that the contact heads at the ends of the de-rotation contact bodies symmetrically contact the target surface. The control mechanism outputs commands to the arm-end drive motor, which rotates forward, driving the gear and rack transmission mechanism to extend the arms. The linear guide rail ensures smooth sliding. When the rack extension amount reaches the optimal extension amount, the extension limit switch is triggered, the motor stops rotating, and the extension and retraction phase is completed. Step 3: Flexible Contact Stage The external output module of the de-rotating rod battery includes a control module, a voltage regulator, and a voltage amplifier. It outputs 1kV voltage to the dielectric elastomer 11 via wires, maintaining the initial stiffness of the arm at 10kN / m, i.e., a flexible contact state. Simultaneously, it outputs commands to drive the intermediate shaft and the de-rotating rod's rotation axis to slowly approach the target. The contact head of the de-rotating contact gradually approaches the target surface. A pressure sensor monitors the contact pressure in real time. When the pressure reaches a preset contact threshold, a feedback signal is sent to the control mechanism. The control mechanism outputs commands to stop the attitude motor and maintain the current position of the telescopic motor. The dielectric elastomer voltage and contact pressure are recorded at this time, completing the contact phase. Step 4: Variable stiffness derotation stage: Based on the initial rotational speed of the target, the control mechanism activates the "high-speed despinning" parameter. The despinning rod battery outputs 3.5kV voltage to the dielectric elastomer, increasing the elastic modulus, raising the arm stiffness, and increasing the frictional torque between the contact head and the target surface. This frictional torque is opposite to the target's rotational direction, gradually reducing the target's rotational speed. Simultaneously, the vision sensor updates the rotational speed data every 100ms: ① When the rotational speed drops to 40° / s, the voltage drops to 2kV, the stiffness is adjusted to 18kN / m, and the frictional torque drops to 1N·m; ② When the rotational speed drops to 15° / s, the voltage drops to 0.5kV, the stiffness is adjusted to 5kN / m, and the frictional torque drops to 0.5N·m. During the despinning process, the dielectric elastomer strain gauge provides real-time feedback on the DE strain. The control mechanism calculates the stiffness based on the strain. If the stiffness deviation is >5%, the voltage is immediately increased by 0.1kV to correct the stiffness to 42kN / m. The pressure sensor continuously monitors the contact pressure; if the pressure rises to 55N, the voltage is immediately reduced by 0.5kV. And control the attitude motor to make a reverse fine adjustment of 1° until the pressure is restored to 30N; Step 4: Stabilization and Completion Phase When the visual sensor detects that the target satellite's rotation speed has dropped to the despinning stabilization threshold, the control mechanism outputs a "despinning complete" signal: ① The high-voltage power supply outputs 0V, DE returns to its expanded state, and the stiffness drops to 1.2kN / m; ② The contact pressure is maintained at 25N, and the target's attitude is stabilized by the flexible support of the low-stiffness arm; The stabilization phase lasts for 10 seconds, during which the rotation speed fluctuation is monitored in real time. If the parameters are abnormal, fine-tuning is immediately initiated. After the stabilization period ends, the control module sends a "despinning complete" signal to the service satellite via the RS485 bus, and the service satellite can then carry out subsequent acquisition, maintenance, and other tasks; If no further operation is required, the control module drives the telescopic motor to reverse, retracting the arm to the retraction limit, the attitude motor returns to the mechanical zero point, and the device enters standby mode.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Dynamically adjustable stiffness: By utilizing the electric field-induced stiffness change characteristics of dielectric elastomer, the despin stiffness can be continuously adjusted within the range of 1MPa~100MPa, adapting to a wide range of target rotation speeds of 115° / s~150° / s, avoiding the problems of high-speed impact and low despin efficiency at low speeds; (2) High arm freedom: The shaft drive motor has dual degrees of freedom of rotation and pitch. Combined with the coordinated action of two symmetrical despin arms, it can adapt to the complex attitude of space targets, significantly improving operational flexibility; (3) Strong space adaptability: Using lightweight materials (carbon fiber, titanium alloy, dielectric elastomer), the overall weight is less than 5kg, meeting the weight constraints of space missions; and there is no fuel consumption or mechanical wear, making it suitable for long-term on-orbit missions; (4) High despin accuracy: Through torque feedback and voltage closed-loop control, the contact torque control accuracy during despin can reach ±0.1N・m, and the final target rotation speed can be stabilized within ±0.5° / s, meeting the attitude requirements of subsequent capture operations. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the operation of the present invention.

[0017] Figure 2 This is a schematic diagram illustrating the operation of the present invention.

[0018] Figure 3 This is a schematic diagram of the variable stiffness anti-rotation rod of the present invention.

[0019] Figure 4 This is a schematic diagram of the variable stiffness anti-rotation rod of the present invention.

[0020] Figure 5 This is a schematic diagram of the variable stiffness anti-rotation rod of the present invention.

[0021] Figure 6 This is a schematic diagram of the variable stiffness anti-rotation rod of the present invention.

[0022] Reference numerals: 1. Satellite body; 2. Arm anti-rotation rod body; 3. Anti-rotation rod fixing base; 4. Arm rotation motor; 5. Anti-rotation rod housing; 6. Anti-rotation rod battery; 7. Output element; 8. Fixing component; 9. Arm end drive motor; 10. Wire; 11. Dielectric elastomer; 12. Gear; 13. Reducer; 14. Solar panel; 15. Anti-rotation contact body; 16. Rack; 17. Slide rail; 18. Intermediate shaft servo motor. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] This invention discloses a variable stiffness despinning arm based on a dielectric elastomer for non-cooperative space targets, relating to the field of space non-cooperative target acquisition and despinning technology. It aims to solve the problems of existing space despinning devices, such as non-adjustable stiffness, weak adaptability to targets with different rotational speeds, and poor operational flexibility due to insufficient arm degrees of freedom. The despinning device includes a support assembly, two symmetrically arranged despinning arm assemblies, and a control module. The support assembly achieves multi-degree-of-freedom adjustment of the despinning arms via a central shaft drive motor. The despinning arm assemblies drive the dielectric elastomer to rotate via an arm-end drive motor to generate braking torque. Simultaneously, utilizing the electric field-induced stiffness variation characteristic of the dielectric elastomer, the control module adjusts the applied voltage to achieve dynamic stiffness adaptation. This invention can flexibly adjust the despinning stiffness and arm attitude according to the real-time rotational speed of the non-cooperative space target (such as a tumbling satellite), adapting to a wide range of rotational speeds from 15° / s to 150° / s. It offers high despinning accuracy, good operational compliance, and no fuel consumption, making it suitable for long-term space missions.

[0025] The support assembly of this invention includes an intermediate shaft, an intermediate shaft servo motor, and a fixed base. The intermediate shaft vertically penetrates the fixed base, and the intermediate shaft drive motor is connected to the intermediate shaft for driving the intermediate shaft to rotate around its own axis or to tilt the intermediate shaft vertically to adjust the spatial attitude of the anti-rotation arm. Two symmetrically distributed anti-rotation rod assemblies are included, each comprising an arm body, an arm rotation motor, and a dielectric elastomer unit. One end of the arm body is fixedly connected to the intermediate shaft, and the other end extends to the target action area. The arm rotation motor is fixed to the free end of the arm body, and its output shaft is connected to the dielectric elastomer unit. A transmission connection is used to drive the dielectric elastomer unit to rotate around the axis of the arm body; the dielectric elastomer unit is a multi-layer composite structure, and its two electrical terminals are electrically connected to the control module through wires, and its stiffness can be adjusted by changing the applied voltage; the control module is electrically connected to the arm rotation motor, the arm end drive motor and the dielectric elastomer unit respectively, and is used to receive the real-time rotation speed signal of the non-cooperative target in space, output control commands to the axis drive motor to adjust the posture of the derotating arm, to the arm end drive motor to control the rotation speed of the dielectric elastomer unit, and to the dielectric elastomer unit to adjust the applied voltage and thus change its stiffness.

[0026] The dielectric elastomer unit of the present invention comprises an upper electrode layer, a dielectric elastomer base layer and a lower electrode layer stacked sequentially; the dielectric elastomer base layer is made of silicon-based dielectric elastomer material; the upper electrode layer and the lower electrode layer are both flexible conductive films, which are made of carbon nanotube / polyimide composite conductive materials.

[0027] The intermediate shaft drive motor of this invention is a dual-degree-of-freedom servo motor, possessing rotational freedom (rotation angle range 0°~270°) around the intermediate shaft axis and pitch freedom (pitch angle range -30°~30°) along the vertical plane, and is equipped with a reduction mechanism with a reduction ratio of 1:50~1:100; the arm-end drive motor is a brushless DC servo motor with an output speed range of 0~1000rpm, equipped with a torque sensor, which can provide real-time feedback of the torque signal when the dielectric elastomer unit contacts a non-cooperative target in space to the control module; The control module includes a signal acquisition unit, a processor, and a drive unit. The signal acquisition unit receives rotational speed detection signals (such as visual sensor or lidar signals) from non-cooperative targets in space and feedback signals from torque sensors. The processor adopts an FPGA+ARM architecture and is used to calculate the optimal stiffness adjustment voltage and motor speed based on the acquired signals. The drive unit includes a motor driver and a high-voltage power supply module. The motor driver drives the shaft drive motor and the arm-end drive motor, and the high-voltage power supply module provides an adjustable DC voltage of 0~5kV to the dielectric elastomer unit. The arm body is made of carbon fiber composite material, with a length of 0.5m~1.5m, a hollow rectangular cross-section, and a wall thickness of 5mm~10mm to reduce weight and ensure structural strength. In the multilayer composite structure of the dielectric elastomer unit, a flexible insulating isolation layer is provided between adjacent dielectric elastomer base layers. The isolation layer is made of polytetrafluoroethylene material with a thickness of 2μm~5μm and is used to prevent interlayer breakdown. It also includes a buffer assembly, which is located at the connection between the arm body and the intermediate shaft and is made of polyurethane elastic material to absorb the vibration generated by the target impact during the despinning process. Example

[0028] This example presents a spatial non-cooperative target variable stiffness derotation device based on a dielectric elastomer, and its actual working state structural schematic diagram is shown below. Figure 1 As shown.

[0029] In this example, the component selection and assembly are as follows: (1) Assembly of support components: The anti-rotation rod fixing base 3 is made of aluminum alloy and is connected to the satellite body 1 by 4 M8 bolts; the intermediate shaft of the anti-rotation rod fixing base 3 is a Φ30mm hollow titanium alloy tube with a length of 300mm, which is connected to the fixing base by a deep groove ball bearing; the intermediate shaft servo motor 18 is a servo motor of model DS-200D (rated power 80W, angle accuracy ±0.1°), and the motor output gear meshes with the intermediate shaft gear (transmission ratio 1:20) to ensure smooth attitude adjustment. The arm rotation motor 4 is a Demeter motor DM40013A2-60 (rated speed 3000rpm, rated torque 1.2N・m), and the reducer 13 is a SIAMG reducer SAB62-1-60-46M4 series; (2) Assembly of the anti-rotation arm assembly: The main body 2 of the anti-rotation arm is made of 6061 aluminum alloy I-shaped cross section (length 1200mm, cross section size 40mm×20mm), and is connected to the intermediate shaft by flange bolts; the arm end drive motor 9 is a BLDC-150 brushless DC motor (rated speed 1200rpm, rated torque 0.8N・m), which is fixed to the end of the arm by screws; the dielectric elastomer 11 unit has a diameter of 150mm, and the multilayer structure parameters are: flexible substrate layer (polyimide, 30μm), dielectric elastomer functional layer (silicon-based, 200μm), conductive connection layer (silver nanowire, 10μm), and surface micro-bump height 5μm. (3) Control module assembly: The control module is integrated inside the satellite body 1. The signal acquisition unit adopts the ADS1256 16-bit ADC chip (sampling frequency 1kHz), the core processing unit adopts the STM32H743 ARM processor, and the drive unit includes a motor driver (supporting PWM control) and a high-voltage power supply module (output 0~3kV, ripple <0.5%). The pressure sensor is a flexible pressure sensor of model FSR402, which is attached between the dielectric elastomer and the coupling.

[0030] (1) Initialization and attitude alignment phase: When the service satellite approaches the target satellite to a distance of 50m, the visual sensor activates, acquiring the target satellite's three-dimensional attitude and transmitting it to the de-rotation rod control module via RS485 bus. The control module performs initialization: ① The intermediate axis servo motor 18 drives the intermediate axis back to its mechanical zero point; ② The arm-end drive motor 9 drives the arm to retract to its retraction limit; ③ The pressure sensor and strain gauge zero points are calibrated; ④ The "high-speed de-rotation" parameter package is loaded. Attitude alignment: Based on the target attitude data, the processor calculates the required horizontal rotation angle and vertical swing angle of the intermediate axis, outputting PWM commands to the attitude motor driver. The intermediate axis servo motor 18 drives the intermediate axis to move, and the variable stiffness de-rotation rod arm-end drive motor 9 drives the de-rotation rod to move. The vertical laser tracker provides real-time attitude feedback, and the PID algorithm corrects errors. After alignment is completed, the extension / retraction phase begins.

[0031] (2) Arm extension and retraction phase: The control module calculates the optimal extension of the double-rotation arm (700mm, ensuring symmetrical contact of the end contact head with the target surface) based on the target satellite diameter (2m) and outputs a command to the arm-end drive motor 9. The arm-end drive motor 9 rotates forward (3000rpm, and the rack moves at a speed of 50mm / s after deceleration), driving the gear 12 and rack 16 transmission mechanism to extend the arm. The linear guide rail ensures smooth sliding, and the encoder provides real-time feedback on the rack position (accuracy ±0.1mm) during the process. When the rack 16 extends to 700mm, the extension limit switch is triggered, the motor stops rotating, and the extension phase is completed. At this time, the total length of the arm is 850mm, and the contact head is about 10mm away from the target surface.

[0032] (3) Flexible contact stage: The external output module 7 (control module, voltage regulator, voltage amplifier, etc.) of the de-rotating rod battery 6 outputs a 1kV voltage to the dielectric elastomer unit 11 through the wire 10, maintaining the initial stiffness of the arm at 10kN / m (flexible contact state). At the same time, it outputs commands to the attitude motor, driving the intermediate shaft and the de-rotating rod rotation axis to slowly approach the target. The contact head gradually approaches the target surface, and the pressure sensor monitors the contact pressure in real time (sampling frequency 1kHz). When the pressure reaches 25N (preset contact threshold), it feeds back a signal to the control module. The control module immediately outputs commands: ① The attitude motor stops moving; ② The telescopic motor maintains its current position; ③ The dielectric elastomer voltage and contact pressure are recorded at this time, and the contact phase is completed.

[0033] (4) Variable stiffness derotation stage: Based on the initial target rotation speed of 80° / s, the control module invokes the "high-speed despinning" parameter. The despinning rod battery 6 outputs 3.5kV to the dielectric elastomer unit 11, resulting in a DE contraction of 4mm, an elastic modulus increase to 35MPa, an arm stiffness of 42kN / m, and an increased frictional torque between the contact head and the target surface to 2N・m (opposite to the target's rotation direction). The frictional torque gradually reduces the target rotation speed, and the vision sensor updates the rotation speed data every 100ms: ① When the rotation speed drops to 40° / s, the voltage drops to 2kV, the stiffness is adjusted to 18kN / m, and the frictional torque drops to 1N・m; ② When the rotation speed drops to 15° / s, the voltage drops to 0.5kV, the stiffness is adjusted to 5kN / m, and the frictional torque drops to 0.5N・m. During the despinning process, the strain gauge provides real-time feedback on the DE. Strain (sampling frequency 1kHz), the control module calculates stiffness based on strain. If the stiffness deviation is >5% (e.g., the stiffness drops to 38kN / m due to target disturbance), the voltage is immediately increased by 0.1kV to correct the stiffness to 42kN / m. The pressure sensor continuously monitors the contact pressure. If the pressure rises to 55N, the voltage is immediately reduced by 0.5kV and the attitude motor is controlled to make a reverse fine adjustment of 1° until the pressure recovers to 30N.

[0034] (4) Stability and Completion Stage: When the visual sensor detects that the target satellite's rotation speed drops to ±0.3° / s (derotation stabilization threshold), the control module outputs a "derotation complete" signal: ① The high-voltage power supply outputs 0V, DE returns to its expanded state, and the stiffness drops to 1.2kN / m; ② The contact pressure is maintained at 25N, and the target's attitude is stabilized through the flexible support of the low-stiffness arm; The stabilization phase lasts for 10s, during which the rotation speed fluctuation (required to be ≤±0.1° / s) and contact pressure (required to be 20~30N) are monitored in real time. If the parameters are abnormal, fine-tuning is initiated immediately (e.g., when the rotation speed rises to 0.5° / s, a 0.2kV voltage is briefly output to increase stiffness); After the stabilization period ends, the control module sends a "derotation complete" signal to the service satellite via the RS485 bus, and the service satellite can carry out subsequent acquisition, maintenance, and other tasks; If no further operation is required, the control module drives the telescopic motor to reverse, retracting the arm to the retraction limit, the attitude motor returns to the mechanical zero point, and the device enters standby mode.

Claims

1. A spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer, characterized in that, The system includes a support assembly comprising an intermediate shaft, an intermediate shaft servo motor, and a fixed base. The intermediate shaft vertically penetrates the fixed base. The intermediate shaft servo motor is connected to the intermediate shaft for driving the intermediate shaft to rotate around its own axis or to tilt the intermediate shaft vertically, thereby adjusting the spatial posture of the arm anti-rotation body. Two symmetrically arranged anti-rotation rod assemblies are respectively mounted on the intermediate shaft. Each anti-rotation rod assembly includes an arm anti-rotation body, an arm rotation motor, and an anti-rotation contact body. The arm anti-rotation body has a strip-shaped anti-rotation rod shell. The outer shell is provided with a linear slide rail along the length of the anti-rotation rod outer shell, and a slider that cooperates with the slide rail. The anti-rotation contact body is fixedly connected to the slider. The anti-rotation contact body includes a long strip shell connected to the slider. The shell contains two or more dielectric elastomers. The dielectric elastomers are connected to a battery and a control mechanism located at the rear end of the anti-rotation rod outer shell via wires. The anti-rotation rod outer shell is also provided with an arm-end drive motor and a gear connected to the output shaft of the arm-end drive motor. The outer side of the anti-rotation contact body is provided with a rack that meshes with the gear. The rack extends along the length of the anti-rotation contact body. The dielectric elastomer is a multilayer composite structure, and its two electrical terminals are electrically connected to the control module through wires so that its stiffness can be adjusted by changing the applied voltage. The control mechanism is also electrically connected to the arm rotation motor, the arm end drive motor, and the dielectric elastomer, respectively, to receive the real-time rotation speed signal of the non-cooperative target in space, and output control commands to the shaft drive motor to adjust the posture of the derotating arm, to the arm end drive motor to control the rotation speed of the dielectric elastomer unit, and to the dielectric elastomer unit to adjust the applied voltage and thus change its stiffness.

2. The spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer according to claim 1, characterized in that, The elongated shell of the despinning contactor is made of an elastic material, which is used to improve the stiffness adjustment sensitivity of the despinning contactor while supporting and fixing the rack.

3. The spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer according to claim 1, characterized in that, The anti-rotation rod housing is also equipped with a limit switch for detecting the extension length of the anti-rotation contact body. The anti-rotation contact body is equipped with a pressure sensor to collect pressure data when it contacts the target. It is also equipped with a vision sensor connected to the control mechanism to collect data such as the target rotation speed.

4. The spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer according to claim 1, characterized in that, The dielectric elastomer unit includes an upper electrode layer, a dielectric elastomer base layer, and a lower electrode layer stacked sequentially. The dielectric elastomer base layer is made of silicon-based dielectric elastomer material. Both the upper electrode layer and the lower electrode layer are flexible conductive films made of carbon nanotube / polyimide composite conductive material. In the multilayer composite structure of the dielectric elastomer, a flexible insulating isolation layer is provided between adjacent dielectric elastomer base layers. The isolation layer is made of polytetrafluoroethylene material with a thickness of 2μm to 5μm to prevent interlayer breakdown.

5. The spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer according to claim 1, characterized in that, The intermediate shaft drive motor is a dual-degree-of-freedom servo motor, possessing rotational freedom around the intermediate shaft axis and pitch freedom along the vertical plane, and is equipped with a reduction mechanism with a reduction ratio of 1:50 to 1:100; the arm-end drive motor is a brushless DC servo motor with an output speed range of 0 to 1000 rpm, and is equipped with a torque sensor to provide real-time feedback of the torque signal when the dielectric elastomer unit contacts the non-cooperative target in space to the control module.

6. The spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer according to claim 1, characterized in that, The control mechanism is located inside the satellite and includes a signal acquisition unit, a processor, and a drive unit. The signal acquisition unit is used to receive rotational speed detection signals from non-cooperative targets in space and feedback signals from torque sensors. The processor adopts an FPGA+ARM architecture and is used to calculate the optimal stiffness adjustment voltage and motor speed based on the acquired signals. The drive unit includes a motor driver and a high-voltage power supply module. The motor driver is used to drive the shaft drive motor and the arm-end drive motor, and the high-voltage power supply module is used to provide an adjustable DC voltage of 0~5kV to the dielectric elastomer.

7. The spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer according to claim 1, characterized in that, The arm's despinning body is made of carbon fiber composite material, with a length of 0.5m to 1.5m, a hollow rectangular cross-section, and a wall thickness of 5mm to 10mm, in order to reduce weight and ensure structural strength.

8. An application of the spatial non-cooperative target variable stiffness despinning device based on a dielectric elastomer as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Initialization and Attitude Alignment Phase: When the service satellite approaches the target satellite to a distance of 50m, the visual sensor is activated, acquires the three-dimensional attitude of the target satellite, and transmits it to the anti-rotation rod control mechanism via RS485 bus. The control mechanism then performs initialization. Step 2: Arm extension and retraction phase: The control mechanism calculates the optimal extension amount of the dual-arm de-rotation body based on the diameter of the target satellite, ensuring that the contact heads at the ends of the de-rotation contact bodies symmetrically contact the target surface. The control mechanism outputs commands to the arm-end drive motor, which rotates forward, driving the gear and rack transmission mechanism to extend the arms. The linear guide rail ensures smooth sliding. When the rack extension amount reaches the optimal extension amount, the extension limit switch is triggered, the motor stops rotating, and the extension and retraction phase is completed. Step 3: Flexible Contact Stage The external output module of the de-rotating rod battery includes a control module, a voltage regulator, and a voltage amplifier. It outputs 1kV voltage to the dielectric elastomer 11 via wires, maintaining the initial stiffness of the arm at 10kN / m, i.e., a flexible contact state. Simultaneously, it outputs commands to drive the intermediate shaft and the de-rotating rod's rotation axis to slowly approach the target. The contact head of the de-rotating contact gradually approaches the target surface. A pressure sensor monitors the contact pressure in real time. When the pressure reaches a preset contact threshold, a feedback signal is sent to the control mechanism. The control mechanism outputs commands to stop the attitude motor and maintain the current position of the telescopic motor. The dielectric elastomer voltage and contact pressure are recorded at this time, completing the contact phase. Step 4: Variable stiffness derotation stage: Based on the initial rotational speed of the target, the control mechanism activates the "high-speed despinning" parameter. The despinning rod battery outputs 3.5kV voltage to the dielectric elastomer, increasing the elastic modulus, raising the arm stiffness, and increasing the frictional torque between the contact head and the target surface. This frictional torque is opposite to the target's rotational direction, gradually reducing the target's rotational speed. Simultaneously, the vision sensor updates the rotational speed data every 100ms: ① When the rotational speed drops to 40° / s, the voltage drops to 2kV, the stiffness is adjusted to 18kN / m, and the frictional torque drops to 1N·m; ② When the rotational speed drops to 15° / s, the voltage drops to 0.5kV, the stiffness is adjusted to 5kN / m, and the frictional torque drops to 0.5N·m. During the despinning process, the dielectric elastomer strain gauge provides real-time feedback on the DE strain. The control mechanism calculates the stiffness based on the strain. If the stiffness deviation is >5%, the voltage is immediately increased by 0.1kV to correct the stiffness to 42kN / m. The pressure sensor continuously monitors the contact pressure; if the pressure rises to 55N, the voltage is immediately decreased by 0.5kV. And control the attitude motor to make a reverse fine adjustment of 1° until the pressure is restored to 30N; Step 4: Stabilization and Completion Phase When the visual sensor detects that the target satellite's rotation speed has dropped to the despin stabilization threshold, the control mechanism outputs a "despin complete" signal: ① The high-voltage power supply outputs 0V, DE returns to its expanded state, and the stiffness drops to 1.2kN / m; ② The contact pressure is maintained at 25N, and the target's attitude is stabilized by the flexible support of the low-stiffness arm; The stabilization phase lasts for 10 seconds, during which the rotation speed fluctuation is monitored in real time. If the parameters are abnormal, fine-tuning is immediately initiated. After the stabilization period ends, the control module sends a "despin complete" signal to the service satellite via the RS485 bus, and the service satellite can then carry out subsequent acquisition, maintenance, and other tasks. If no further operation is required, the control module drives the telescopic motor to reverse, retracting the arm to the retraction limit. The posture motor returns to the mechanical zero point, and the device enters standby mode.

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