Piezoelectric focusing locking and automatic unlocking device

Abstract

The application discloses a piezoelectric focusing locking and automatic unlocking device, which comprises a main force support, a circuit box mounting rack, a focusing support, a piezoelectric motor, a guide rail, a focal plane circuit box assembly, a heat dissipation assembly, a memory metal separation nut and an unlocking control system. In the launching stage, the separation nut rigidly locks the main force support and the circuit box mounting rack, the output end of the piezoelectric motor is connected with the focusing support through a limiting structure to form an unloading gap, and the device is in a no-load protection state and is isolated from the launching impact load. After entering the orbit, the unlocking control system drives the separation nut to be unlocked with low impact, releases the displacement freedom degree of the circuit box mounting rack, and the piezoelectric motor drives the focal plane circuit box to realize sub-micron high-precision in-orbit focusing. The unlocking control system integrates temperature compensation, current monitoring, state feedback and ground test modules, supports full-process closed-loop management and control and ground repeated verification. The piezoelectric focusing locking and automatic unlocking device has the characteristics of impact resistance, high reliability and light weight.

Description

Technical Field

[0001] This invention relates to the field of space optical payload technology for aerospace remote sensing cameras, specifically a piezoelectric focusing locking and automatic unlocking device. Background Technology

[0002] High-precision remote sensing cameras are core payloads for satellite Earth observation and space exploration. To ensure on-orbit imaging clarity, they need to be equipped with high-precision micro-displacement focusing mechanisms to achieve lens focus compensation. Currently, the mainstream focusing drive component is the piezoelectric motor, which has outstanding advantages such as high stepping accuracy, fast response speed, no electromagnetic interference, compact structure, and light weight, making it well-suited for the precision focusing requirements of micro-displacement in space.

[0003] However, piezoelectric motors have inherent defects. Their structural rigidity is low, and their impact and vibration resistance is extremely poor. They cannot withstand the strong vibration, high overload, and large impact mechanical environment during rocket launch. During the launch phase, structural deformation, internal chip damage, and accuracy deviation are very likely to occur, leading to the failure of on-orbit focusing function and directly affecting the on-orbit imaging performance of remote sensing cameras.

[0004] Currently, traditional focusing and locking mechanisms in the industry mostly adopt structures such as gear racks, motor screws, and mechanical latches. These mechanisms have many drawbacks: First, they are complex in structure, have many parts, and are heavy overall, which does not meet the lightweight design requirements of aerospace payloads; second, they have large transmission gaps and low focusing accuracy, which cannot meet the needs of sub-micron level precision focusing; third, they have large locking and unlocking impacts and poor on-orbit reliability, and are prone to jamming and failure in the complex high and low temperature and vacuum environment of space; fourth, they cannot meet the adaptation requirements of fully rigid locking during the launch phase and low-impact automatic unlocking in orbit.

[0005] In summary, the current technology lacks an integrated piezoelectric focusing locking and unlocking device that combines lightweight design, high rigidity locking, low impact unlocking, high-precision focusing, and can be fully verified on the ground. This has become a key technical bottleneck restricting the stable on-orbit operation of high-precision remote sensing cameras. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as weak impact resistance of piezoelectric motors, large weight of traditional locking mechanisms, high unlocking impact, poor reliability, and inability to simultaneously achieve launch protection and on-orbit precision focusing. This invention provides a piezoelectric focusing locking and automatic unlocking device suitable for the focal plane circuit box of a remote sensing camera. It achieves full rigid locking protection during rocket launch, low-impact automatic unlocking on-orbit, and high-precision submicron-level focusing. It also features lightweight design, high reliability, strong environmental adaptability, and the ability to be repeatedly tested on the ground.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a piezoelectric focusing locking automatic unlocking device suitable for the focal plane circuit box of a remote sensing camera, comprising a main load-bearing bracket, a circuit box mounting bracket, a focusing bracket, a piezoelectric motor, a guide rail, a focal plane circuit box assembly, and a heat dissipation assembly. The circuit box mounting bracket is slidably mounted on the main load-bearing bracket via the guide rail. The piezoelectric motor is fixed to the circuit box mounting bracket, and its output end is connected to the focusing bracket via a transmission assembly. The focal plane circuit box assembly and the heat dissipation assembly are respectively mounted on the main load-bearing bracket and the circuit box mounting bracket. The device also includes a shape memory metal release nut and an unlocking control system. The memory metal release nut is rigidly locked between the main load-bearing bracket and the circuit box mounting bracket, and is used to achieve a rigid connection between the main load-bearing bracket and the circuit box mounting bracket during the launch phase, thus isolating the launch impact load. The unlocking control system includes an on-board power supply module, an unlocking control unit, a current detection module, a temperature compensation module, a status feedback module, and a ground testing module. The unlocking control unit is electrically connected to the on-board power supply module, the current detection module, the temperature compensation module, and the status feedback module, and is used for on-orbit automatic control of unlocking the shape memory metal release nut, calibration of operating parameters, closed-loop monitoring of operating status, and supports repeated performance testing on the ground. The temperature compensation module is used to collect the real-time ambient temperature of the memory metal release nut and, in combination with the real-time unlocking drive current collected by the current detection module, generate a temperature-compensated drive current control signal to counteract the influence of ambient temperature on the phase change efficiency of the memory metal release nut. The ground test module is used to simulate a ground test environment to verify the drive control logic of the unlocking control system. The unlocking test is repeated by replacing the new memory metal release nut to verify the consistency of the drive control logic of the unlocking control system under different working conditions. During the launch phase, the shape memory metal release nut remains locked, and the piezoelectric motor is in an unloaded protective state. After the satellite enters orbit and stabilizes, the unlocking control system drives the shape memory metal release nut to unlock, releasing the displacement degree of freedom of the circuit box mounting bracket. The piezoelectric motor drives the focusing bracket and the focal plane circuit box to perform micro-displacement movement, achieving high-precision on-orbit focusing.

[0008] Preferably, the no-load protection state of the piezoelectric motor is as follows: when the shape memory metal release nut is tightened, the load on the circuit box mounting bracket is entirely borne by the release nut and the main load-bearing bracket. The output end of the piezoelectric motor forms an unloading gap with the focusing bracket through the limiting structure, so that the static load on the output end of the piezoelectric motor is released or transferred to the main load-bearing bracket, thereby being in a no-load protection state.

[0009] Preferably, the limiting structure is a U-shaped groove fixed on the focusing bracket, and the output end of the piezoelectric motor is placed in the U-shaped groove. The groove width is greater than the diameter of the output end. In the locked state, the output end does not contact the groove wall, realizing non-contact unloading. After unlocking, the output end moves with the piezoelectric motor, contacts the groove wall and pushes the focusing bracket to move.

[0010] Preferably, the focal plane circuit box assembly includes a primary focal plane circuit box and a secondary focal plane circuit box. The primary focal plane circuit box is fixedly installed on the circuit box mounting frame and can move synchronously with the circuit box mounting frame. The primary focal plane circuit box has a built-in detector and PCB board, and is equipped with a primary upper cover plate, a primary lower cover plate, and a primary plate frame. The secondary focal plane circuit box is fixedly installed on the main load-bearing bracket and is a fixed-end circuit assembly, and is equipped with a secondary upper cover plate, a secondary lower cover plate, and a secondary plate frame.

[0011] Preferably, the heat dissipation assembly includes a small heat pipe, a large heat pipe, a single-split heat sink, a double-split heat sink, a heat sink bracket, and a double-split heat sink support column; the heat sink bracket is fixed to the surface of the single-split coke surface circuit box, the single-split heat sink is mounted on the heat sink bracket, and the heat sink bracket maintains thermal contact with the single-split coke surface circuit box through a flexible thermally conductive pad; the small heat pipe connects the single-split coke surface circuit box and the single-split heat sink; the double-split heat sink support column is fixed to the main load-bearing bracket, the double-split heat sink is mounted on the double-split heat sink support column, and the large heat pipe connects the double-split coke surface circuit box and the double-split heat sink, forming an independent heat dissipation structure for both dynamic and static ends.

[0012] Preferably, a flexible cable bundle is provided between the focal surface circuit box and the main support bracket. The flexible cable bundle is S-shaped or U-shaped, with one end connected to the PCB board inside the focal surface circuit box and the other end fixed to the connector on the main support bracket to accommodate the micro-displacement movement of the focal surface circuit box during focusing. Mechanical limit blocks are provided at both ends of the guide rail to limit the extreme displacement stroke of the circuit box mounting bracket.

[0013] Preferably, the shape memory metal release nut is a non-flammable release mechanism made of shape memory alloy, with a rated load capacity of 1kN, an unlocking impact of ≤200g, and an operating temperature range of -70℃ to +70℃.

[0014] Preferably, the temperature compensation module includes a thermistor and a comparator circuit. The thermistor is attached to the surface of the shape memory alloy release nut and is used to collect the real-time ambient temperature of the shape memory alloy release nut and output a temperature detection signal. The comparator circuit receives the temperature detection signal and compares it with a preset temperature threshold, and outputs the temperature deviation to the unlocking control unit. The unlocking control unit generates a temperature-compensated target current signal based on the temperature deviation. The current detection module includes a sampling resistor and a differential amplifier. The sampling resistor is connected in series in the unlocking drive current loop. The differential amplifier is used to collect the differential voltage across the sampling resistor and output an actual current detection signal. The unlocking control unit compares the actual current detection signal with the temperature-compensated target current signal, and adaptively adjusts the actual duty cycle of the unlocking drive current using PWM based on the comparison result to offset the influence of the real-time ambient temperature on the shape memory alloy phase transformation efficiency of the shape memory alloy release nut, while simultaneously suppressing the interference of bus voltage fluctuations on the drive current, ensuring that the actual drive current applied to the heating element of the shape memory alloy release nut is stable within the rated operating range.

[0015] Preferably, the status feedback module collects the locking and unlocking status signals of the piezoelectric focusing locking automatic unlocking device through a miniature displacement sensor and a pressure sensor, and transmits the locking and unlocking status signals to the on-board control system to obtain the feedback working status and fault alarm signals of the piezoelectric focusing locking automatic unlocking device, thereby realizing closed-loop control of the entire unlocking and focusing process. The ground testing module includes a dedicated testing fixture, which is used to simulate the high and low temperature, vacuum and voltage fluctuation conditions in space to construct a ground simulation testing environment. In the ground simulation testing environment, the activated shape memory metal release nut is removed and replaced with a new shape memory metal release nut. The preload and position accuracy during locking are accurately reproduced through the precision thread pair on the dedicated testing fixture. Subsequently, multiple simulated unlocking actions are performed to verify the consistency of the drive control logic of the unlocking control system under different simulated conditions.

[0016] Preferably, the piezoelectric motor has submicron-level stepping drive precision, and after unlocking, it can precisely drive the focal plane circuit box to perform a micro-displacement, thereby achieving high-precision focusing and adjustment of the detector.

[0017] Beneficial effects This invention provides a piezoelectric focusing locking automatic unlocking device, which has the following beneficial effects: 1. This piezoelectric focusing locking automatic unlocking device achieves full rigid locking during the launch phase through a memory metal separation nut, effectively isolating the rocket from strong impacts and high vibration loads during launch. It fundamentally solves the industry problems of weak impact resistance, easy damage during launch, and accuracy failure of piezoelectric motors, and greatly improves the launch reliability of the equipment.

[0018] 2. This piezoelectric focusing locking automatic unlocking device, through a dedicated unlocking control system, achieves fully automatic closed-loop unlocking in orbit with an unlocking impact of ≤200g, without pyrotechnic impact or structural damage. The system is equipped with temperature compensation, current monitoring, and status feedback functions, and can be adapted to the extreme temperature environment of space from -70℃ to +70℃, greatly improving unlocking accuracy and stability.

[0019] 3. This piezoelectric focusing and locking automatic unlocking device eliminates the complex transmission and locking structures of traditional gears and lead screws, resulting in a simple and lightweight overall structure that meets the lightweight design requirements of aerospace payloads. It achieves sub-micron level step focusing by relying on a piezoelectric motor, with focusing accuracy far exceeding that of traditional mechanisms, ensuring the high-definition imaging requirements of remote sensing cameras.

[0020] 4. This piezoelectric focusing locking automatic unlocking device is equipped with a ground testing module for the unlocking control system. The memory metal separation nut can be locked and unlocked repeatedly, supporting reliability testing and performance calibration under all ground conditions. This significantly reduces product development and testing costs and improves batch stability.

[0021] 5. This piezoelectric focus locking automatic unlocking device, through the integration of an integrated heat pipe heat dissipation component, can quickly dissipate the working heat of the focus surface circuit box, avoid circuit failure and mechanical deformation caused by high temperature heat accumulation, ensure long-term stable operation of the equipment on the track, and extend the service life of the equipment.

[0022] 6. This piezoelectric focusing locking automatic unlocking device features fully automated closed-loop control of unlocking, status monitoring, and focusing permission switching, requiring no manual intervention. It can automatically alarm for on-orbit faults, is well-suited for long-term unattended operation of satellites, and has extremely high operational reliability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of a piezoelectric focusing locking and automatic unlocking device proposed in this invention; Figure 2 This is a three-dimensional structural diagram of the focal surface circuit box assembly of a piezoelectric focusing locking and automatic unlocking device proposed in this invention; Figure 3 This is a block diagram of the unlocking control system of an automatic unlocking device for piezoelectric focusing and locking proposed in this invention.

[0024] In the diagram: 1. Main load-bearing bracket; 2. Shape memory metal release nut; 3. Focusing bracket; 4. Piezoelectric motor; 5. Circuit box mounting bracket; 6. One-way circuit box for the focal surface; 7. Heat sink bracket; 8. Small heat pipe; 9. One-way heat sink; 10. Guide rail; 11. Two-way heat sink support column; 12. Two-way heat sink; 13. Large heat pipe; 14. Two-way circuit box for the focal surface; 15. Detector; 16. One-way upper cover plate; 17. One-way plate frame; 18. One-way lower cover plate; 19. PCB board; 20. Two-way upper cover plate; 21. Two-way plate frame; 22. Two-way lower cover plate. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] Example 1, please refer to Figures 1 to 3 The present invention provides a technical solution: a piezoelectric focusing locking automatic unlocking device suitable for the focal plane circuit box of a remote sensing camera, the core structure of which includes a main load-bearing bracket 1, a circuit box mounting bracket 5, a focusing bracket 3, a piezoelectric motor 4, a guide rail 10, a focal plane circuit box assembly, a heat dissipation assembly, a memory metal separation nut 2, and an unlocking control system.

[0029] (a) Overall assembly structure The main load-bearing bracket 1 is an integral load-bearing base made of high-strength aerospace-grade aluminum alloy, balancing lightweight design and structural rigidity. The guide rail 10 is a precision linear guide rail, fixed to the inside of the main load-bearing bracket 1. The circuit box mounting bracket 5 is slidably mounted on the guide rail 10 via a slider, allowing for slight horizontal linear displacement along the guide rail. Mechanical limit blocks (not shown in the figure) are provided at both ends of the guide rail 10 to limit the extreme displacement of the circuit box mounting bracket 5, preventing it from colliding with surrounding structures or detaching from the guide rail 10.

[0030] The tail of the piezoelectric motor 4 is fixed to the side wall of the circuit box mounting bracket 5 by bolts, and its front output end is connected to the focusing bracket 3 by a transmission assembly. In this embodiment, the transmission assembly is specifically: a U-shaped groove is fixedly provided on the focusing bracket 3, and the output end of the piezoelectric motor 4 is placed in the U-shaped groove. The groove width is slightly larger than the diameter of the output end, forming a limiting structure.

[0031] (ii) Launch protection structure During the launch phase, the shape memory metal release nut 2 is in a locked state, rigidly fixing the circuit box mounting bracket 5 to the main load-bearing bracket 1. At this time, all the loads on the circuit box mounting bracket 5 (including the piezoelectric motor 4) are transmitted through the release nut 2 and borne by the main load-bearing bracket 1. Simultaneously, a gap of approximately 0.5mm to 1mm is maintained between the output end of the piezoelectric motor 4 and the U-shaped groove wall of the focusing bracket 3. In the locked state, the output end does not contact the groove wall, allowing the static load from the focusing bracket 3 on the output end of the piezoelectric motor 4 to be released or transferred to the main load-bearing bracket 1, thereby achieving a non-contact, no-load protection state and fundamentally isolating the piezoelectric motor from the impact of the launch mechanical load.

[0032] After unlocking, the output of piezoelectric motor 4 steps forward with the motor, contacts the U-shaped groove wall, and pushes the focusing bracket 3 to move. The first step after unlocking is used to eliminate the gap mentioned above. The stroke for eliminating the gap accounts for a very small proportion of the overall focusing stroke and does not affect the final focusing accuracy. Specifically, after unlocking, the control system first drives the piezoelectric motor to step forward until it contacts the U-shaped groove wall, and confirms the contact state through current detection feedback. This position is recorded as the focusing zero reference, and then precise focusing is performed from this starting point.

[0033] (III) Focal surface circuit box assembly The first-stage circuit box 6 is fastened to the circuit box mounting bracket 5 with screws and can move synchronously with the circuit box mounting bracket 5. It integrates a detector 15 and a PCB board 19. The upper and lower sides are respectively equipped with a first-stage upper cover plate 16, a first-stage lower cover plate 18, and a first-stage plate frame 17 to achieve sealing protection. The second-stage circuit box 14 is fixed to the main load-bearing bracket 1. It is a fixed-end circuit assembly and does not need to move with the focusing mechanism. It is also equipped with a second-stage upper cover plate 20, a second-stage lower cover plate 22, and a second-stage plate frame 21.

[0034] A flexible cable bundle (not shown in the figure) is provided between the focal surface circuit box 6 and the main support bracket 1. The flexible cable bundle is S-shaped or U-shaped, with one end connected to the PCB board 19 inside the focal surface circuit box 6 and the other end fixed to the connector on the main support bracket 1 to accommodate the micro-displacement movement of the focal surface circuit box 6 during focusing.

[0035] (iv) Heat dissipation components The heat dissipation assembly is as follows: the heat sink bracket 7 is fixed to the surface of the one-to-6 junction box of the focal surface circuit box. The one-to-6 heat sink 9 is attached to the heat sink bracket 7, and the heat sink bracket 7 maintains thermal contact with the one-to-6 junction box of the focal surface circuit box through a flexible thermal pad, allowing the one-to-6 junction box of the focal surface circuit box to slide slightly relative to the heat sink bracket 7 to ensure a continuous heat dissipation path. The two ends of the small heat pipe 8 are respectively attached to the side wall of the one-to-6 junction box of the focal surface circuit box and the one-to-6 heat sink 9 to achieve rapid heat conduction. The two-to-6 heat sink support column 11 is vertically fixed to the side of the main load-bearing bracket 1, and the two-to-6 heat sink 12 is horizontally mounted on the two-to-6 heat sink support column 11. The two ends of the large heat pipe 13 are respectively connected to the two-to-6 junction box of the focal surface circuit box 14 and the two-to-6 heat sink 12, forming a dual-path independent heat dissipation system to ensure balanced heat dissipation of the dynamic and static circuits.

[0036] (v) Shape memory metal split nuts The shape memory metal release nut 2 employs a non-pyrotechnic release mechanism made of Ti-Ni shape memory alloy. It achieves rigid locking by bolting into the mating holes of the main load-bearing bracket 1 and the circuit box mounting bracket 5. This release nut is a one-time actuation product, bearing all mechanical loads during launch; after orbit insertion, it is unlocked by heating driven by the unlocking control system, exhibiting fast unlocking response and minimal impact. In this embodiment, the shape memory metal release nut 2 has a rated load of 1kN, an unlocking impact ≤200g, and an operating temperature range of -70℃ to +70℃.

[0037] (vi) Unlocking the control system The specific implementation of the unlocking control system is as follows: the unlocking control unit adopts an aerospace-grade embedded control chip (such as FPGA or MCU) and integrates temperature acquisition, current regulation, signal feedback and fault diagnosis functions.

[0038] Temperature compensation module: Includes a high-precision thermistor and comparator circuit. The thermistor is attached to the surface of the shape memory alloy release nut 2 to collect the real-time ambient temperature of the shape memory alloy release nut 2 and output a temperature detection signal; the comparator circuit receives the temperature detection signal and compares it with a preset temperature threshold. Based on the comparison result, it adaptively adjusts the unlocking drive current through PWM (pulse width modulation) to counteract the influence of the real-time ambient temperature on the shape memory alloy phase transformation efficiency of the shape memory alloy release nut 2.

[0039] Current detection module: includes a precision sampling resistor and a differential amplifier. The sampling resistor is connected in series in the unlocking drive current loop. The differential amplifier is used to acquire the differential voltage across the sampling resistor and output a current detection signal to monitor the unlocking drive current value in real time and ensure that the current is stable within the rated operating range.

[0040] The temperature compensation module and the current detection module are not independent open-loop monitoring components, but rather together with the unlocking control unit form a dual closed-loop regulation architecture: Outer ring (temperature compensation ring): Thermistor collects the real-time ambient temperature of the memory metal separating nut 2. The comparator circuit will With preset temperature threshold (In this embodiment, the temperature is set to 20°C) The comparison is performed to generate the temperature deviation. Unlock control unit according to The correction amount of the PWM duty cycle is calculated by the PID algorithm, thereby enabling operation in low-temperature environments ( Increase heating power, in high-temperature environments ( Reduce heating power to offset the effect of ambient temperature on the phase transformation efficiency of shape memory alloy, and ensure that the release nut can obtain consistent thermal power input under different track temperature conditions.

[0041] Inner loop (current closed loop): The sampling resistor is connected in series in the unlocking drive current loop. The differential amplifier acquires the differential voltage across the sampling resistor and outputs a current detection signal. Unlocking the control unit will With rated target current Comparison, when detected Deviation At the same time, instantaneous compensation is performed by adjusting the actual duty cycle of the PWM output of the drive circuit to ensure that the current actually applied to the heating element of the separating nut remains stable within the rated operating range. ±3%) to prevent overcurrent burnout or undercurrent failure caused by bus voltage fluctuations.

[0042] The aforementioned dual closed-loop architecture works in tandem, enabling the unlocking control system to output precise and stable heating energy across the entire temperature range of -70℃ to +70℃ and within a bus voltage fluctuation range of ±10%, thereby ensuring the unlocking reliability of the shape memory metal release nut in extreme space environments.

[0043] Status feedback module: Includes miniature displacement sensor and pressure sensor installed between the contact surface of the separating nut and the main load-bearing bracket. The miniature displacement sensor and pressure sensor collect the locking status signal and unlocking status signal of the piezoelectric focusing locking automatic unlocking device, and transmit the locking status signal and unlocking status signal to the on-board control system to obtain the feedback working status and fault alarm signal of the piezoelectric focusing locking automatic unlocking device, so as to realize the closed-loop control of the entire process of unlocking and focusing.

[0044] Ground testing module: Includes dedicated testing fixtures, which connect to the unlocking control system via a standard electrical interface. Its mechanical interface aligns with the mounting holes of the main load-bearing bracket. This dedicated testing fixture integrates a vacuum simulation chamber, a high- and low-temperature cycling temperature control platform, a programmable power supply, and a data acquisition unit, used to reproduce the space vacuum environment (vacuum level better than 1×10⁻⁶) in a ground environment. -3 The test environment was constructed by measuring the Pa value, high and low temperature alternating environment (-70℃ to +70℃), and bus voltage fluctuation conditions (rated voltage ±10%).

[0045] Since the shape memory alloy release nut 2 is a one-time actuated product, its internal shape memory alloy has undergone a phase change after actuation and cannot be reversed. Therefore, a new release nut must be replaced for each ground unlocking test. The specific operation is as follows: In the ground simulation test environment, firstly, the circuit box mounting bracket 5 assembly is removed from the main load-bearing bracket 1. Using a special disassembly tool, the actuated release nut 2 is removed from the mating mounting holes between the main load-bearing bracket 1 and the circuit box mounting bracket 5. Then, a new, unacted shape memory alloy release nut 2 is installed. The preload torque value and installation position accuracy when the release nut is locked are accurately reproduced using the precision thread pair on the special test fixture to ensure that the initial mechanical boundary conditions are consistent for each test.

[0046] After the replacement is completed, the unlocking control system is activated to perform the unlocking action. The unlocking control unit issues an unlocking command according to the preset timing logic. This command is converted into a heating current with specific pulse width modulation parameters by the drive control circuit (i.e., the power drive circuit integrated inside the unlocking control unit, including the MOSFET drive transistor and its peripheral circuits). This current is applied to the heating element of the shape memory alloy release nut 2, causing its temperature to rise to the phase transition point of the shape memory alloy (approximately 90℃~100℃) and then undergo phase transition unlocking. During the unlocking process, the temperature compensation module collects the ambient temperature in real time and feeds it back to the unlocking control unit. The unlocking control unit dynamically adjusts the PWM duty cycle according to the ambient temperature deviation to correct the heating current. The current detection module collects the drive current value in real time. When the current deviates from the preset threshold, the unlocking control unit automatically adjusts the drive parameters for closed-loop correction.

[0047] After one unlocking test is completed, the miniature displacement sensor in the status feedback module confirms whether the release nut is completely unlocked. The detection result of the status feedback module will be used as the basis for determining the test conclusion. If repeated testing is required to verify consistency, the above replacement, locking, unlocking, and testing process should be repeated multiple times (e.g., no less than 10 times) to simulate the unlocking action.

[0048] (vii) Ground test consistency verification The above-described ground testing process enables multi-dimensional consistency verification of the unlocking control system, specifically including: (1) Consistency verification of drive control circuit In each unlocking test, the drive current waveform recorded by the current detection module (including the peak value of the transient current at startup, the average value of the steady-state heating current, and the power-off decay time constant) is used to characterize the actual output characteristics of the drive control circuit. The current waveforms recorded from multiple tests are superimposed and compared. If the key parameters of each waveform (peak current deviation ≤ ±5%, steady-state current deviation ≤ ±3%, heating time deviation ≤ ±5%) are all within the preset tolerance range, then the electrical output characteristics of the drive control circuit are determined to have batch-to-batch consistency and operating condition stability.

[0049] (2) Software logic consistency verification The control software built into the unlock control unit (including temperature PID regulation algorithm, current closed-loop control algorithm, unlock timing state machine, and fault diagnosis logic) runs according to the same fixed program in each test. The unlock timing signals (including heating start time, phase change completion time, and unlock completion time) recorded by the state feedback module are compared with the command issuance time and current response time recorded by the ground test module's data acquisition unit. This verifies whether the control software's state machine transition logic, timing interrupt response, and fault protection trigger threshold remain consistent across different test rounds and environmental conditions. If the timing characteristic parameter deviation for each test is ≤±2%, the software logic execution is considered consistent.

[0050] (3) Unlock performance consistency verification Key performance indicators (unlocking response time, unlocking impact peak, separation nut stroke, and arrival signal trigger time) from each unlocking test were statistically compared. If the distribution of performance indicators from each test meets the Six Sigma quality control standard (i.e., no deviations within the mean ± 3σ range), then the overall unlocking performance of the unlocking device is determined to have batch stability and consistency under operating conditions.

[0051] Through cross-verification of the three dimensions of drive control circuit consistency, software logic consistency, and unlocking performance consistency, the reliability and repeatability of the unlocking control system throughout its entire life cycle can be comprehensively evaluated. This enables effective verification of the reliability of the device during the entire on-orbit operation process at ground level, thus addressing the industry pain point that disposable pyrotechnic separation products cannot undergo physical functional verification before launch.

[0052] (viii) Operating process of the device During the launch phase: the shape memory metal separation nut 2 is kept in a fully rigid lock, the output end of the piezoelectric motor 4 maintains a gap with the U-shaped groove wall of the focusing bracket 3, and is in a no-load protection state, so the overall equipment has strong resistance to mechanical environment.

[0053] Orbit insertion and unlocking phase: After the satellite has stabilized in orbit, the unlocking control system automatically completes self-checks and parameter calibrations. The unlocking control unit issues a command, and through the coordinated control of the temperature compensation module and the current detection module, outputs an optimized heating current to the shape memory metal release nut 2, causing it to undergo a phase change and unlock.

[0054] During the on-orbit focusing phase: After the status feedback module confirms successful unlocking, the piezoelectric motor 4 first eliminates the initial gap between the output end and the U-shaped groove wall through stepping. Then, according to the imaging command, it precisely drives the focal plane circuit box 6 to perform sub-micron level micro-displacement through the focusing bracket 3, completing high-precision on-orbit focusing. The piezoelectric motor 4 has sub-micron level stepping drive accuracy (the stepping accuracy can reach 0.1μm in this embodiment). After unlocking, it can precisely drive the focal plane circuit box 6 to perform micro-displacement, realizing high-precision focusing of the detector 15. Throughout the process, the heat dissipation components work continuously to ensure the thermal stability of the equipment.

[0055] Example 2

[0056] This embodiment is basically the same in structure as Embodiment 1, except for the fixing method of the piezoelectric motor 4. In this embodiment, the piezoelectric motor 4 is mounted on the circuit box mounting bracket 5 via a flange and shock-absorbing pads, further reducing the impact of minor vibrations on focusing accuracy. The remaining structure and operation are the same as in Embodiment 1, and will not be described again here.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Any person skilled in the art can make modifications or alterations to the disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications or equivalent substitutions made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should be included within the protection scope of the present invention.

Claims

1. A piezoelectric focusing locking automatic unlocking device for a focal plane circuit box of a remote sensing camera, comprising a main support bracket (1), a circuit box mounting bracket (5), a focusing bracket (3), a piezoelectric motor (4), a guide rail (10), a focal plane circuit box assembly, and a heat dissipation assembly, wherein the circuit box mounting bracket (5) is slidably mounted on the main support bracket (1) via the guide rail (10), the piezoelectric motor (4) is fixed to the circuit box mounting bracket (5) and its output end is connected to the focusing bracket (3) via a transmission assembly, and the focal plane circuit box assembly and the heat dissipation assembly are respectively mounted on the main support bracket (1) and the circuit box mounting bracket (5), characterized in that: It also includes a memory metal release nut (2) and an unlocking control system; The memory metal separation nut (2) is rigidly locked between the main load-bearing bracket (1) and the circuit box mounting bracket (5) to achieve rigid connection between the main load-bearing bracket (1) and the circuit box mounting bracket (5) during the launch phase, and to isolate the launch impact load; The unlocking control system includes an on-board power supply module, an unlocking control unit, a current detection module, a temperature compensation module, a status feedback module, and a ground testing module. The unlocking control unit is electrically connected to the on-board power supply module, the current detection module, the temperature compensation module, and the status feedback module, respectively, and is used for on-orbit automatic control of unlocking the memory metal separation nut (2), calibration of working parameters, closed-loop monitoring of working status, and supports repeated performance testing on the ground. The temperature compensation module is used to collect the real-time ambient temperature of the memory metal separation nut (2) and, in combination with the real-time unlocking drive current collected by the current detection module, generate a temperature-compensated drive current control signal to offset the influence of ambient temperature on the phase change efficiency of the memory metal separation nut (2). The ground test module is used to simulate the ground test environment, verify the drive control logic of the unlocking control system in the ground test environment, and repeat the unlocking test by replacing the new memory metal release nut (2) to verify the consistency of the drive control logic of the unlocking control system under different working conditions. During the launch phase, the memory metal separation nut (2) remains locked and the piezoelectric motor (4) is in an unloaded protection state. After the satellite enters orbit and stabilizes, the unlocking control system drives the memory metal separation nut (2) to be energized and unlocked, releasing the displacement degree of freedom of the circuit box mounting bracket (5). The piezoelectric motor (4) drives the focusing bracket (3) and the focal surface circuit box to move slightly, achieving high-precision on-orbit focusing.

2. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The no-load protection state of the piezoelectric motor (4) is as follows: when the memory metal release nut (2) is locked, the load on the circuit box mounting bracket (5) is entirely borne by the release nut (2) and the main load-bearing bracket (1). The output end of the piezoelectric motor (4) forms an unloading gap with the focusing bracket (3) through the limiting structure, so that the static load on the output end of the piezoelectric motor (4) is released or transferred to the main load-bearing bracket (1), thus being in a no-load protection state.

3. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 2, characterized in that: The limiting structure is a U-shaped groove fixed on the focusing bracket (3). The output end of the piezoelectric motor (4) is placed in the U-shaped groove. The groove width is greater than the diameter of the output end. In the locked state, the output end does not contact the groove wall, realizing non-contact unloading. After unlocking, the output end moves with the piezoelectric motor (4), contacts the groove wall and pushes the focusing bracket (3) to move.

4. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The focal surface circuit box assembly includes a focal surface circuit box first trailer (6) and a focal surface circuit box second trailer (14). The focal surface circuit box first trailer (6) is fixedly installed on the circuit box mounting frame (5) and can move synchronously with the circuit box mounting frame (5). The focal surface circuit box first trailer (6) has a built-in detector (15) and PCB board (19), and is equipped with a first trailer upper cover plate (16), a first trailer lower cover plate (18) and a first trailer frame (17). The focal surface circuit box second trailer (14) is fixedly installed on the main load-bearing bracket (1) and is a fixed end circuit assembly, and is equipped with a second trailer upper cover plate (20), a second trailer lower cover plate (22) and a second trailer frame (21).

5. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The heat dissipation assembly includes a small heat pipe (8), a large heat pipe (13), a single-spindle heat sink (9), a double-spindle heat sink (12), a heat sink bracket (7), and a double-spindle heat sink support column (11). The heat sink bracket (7) is fixed to the surface of the single-spindle (6) of the coke surface circuit box, the single-spindle heat sink (9) is mounted on the heat sink bracket (7), and the heat sink bracket (7) maintains thermal contact with the single-spindle (6) of the coke surface circuit box through a flexible thermal pad. The small heat pipe (8) connects the single-spindle (6) of the coke surface circuit box with the single-spindle heat sink (9). The double-spindle heat sink support column (11) is fixed to the main load-bearing bracket (1), the double-spindle heat sink (12) is mounted on the double-spindle heat sink support column (11), and the large heat pipe (13) connects the double-spindle (14) of the coke surface circuit box with the double-spindle heat sink (12), forming an independent heat dissipation structure for the dynamic and static ends.

6. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: A flexible cable bundle is provided between the focal surface circuit box (6) and the main support bracket (1). The flexible cable bundle is S-shaped or U-shaped, with one end connected to the PCB board (19) inside the focal surface circuit box (6) and the other end fixed to the connector on the main support bracket (1) to accommodate the micro-displacement movement of the focal surface circuit box (6) during the focusing process. Mechanical limit blocks are provided at both ends of the guide rail (10) to limit the extreme displacement stroke of the circuit box mounting bracket (5).

7. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The memory metal release nut (2) is a shape memory alloy non-fired release mechanism with a rated load of 1kN, an unlocking impact of ≤200g, and a working temperature range of -70℃ to +70℃.

8. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The temperature compensation module includes a thermistor and a comparator circuit. The thermistor is attached to the surface of the memory metal release nut (2) and is used to collect the real-time ambient temperature of the memory metal release nut (2) and output a temperature detection signal. The comparator circuit receives the temperature detection signal and compares it with a preset temperature threshold, and outputs the temperature deviation to the unlocking control unit. The unlocking control unit generates a temperature-compensated target current signal based on the temperature deviation. The current detection module includes a sampling resistor and a differential amplifier. The sampling resistor is connected in series in the unlocking drive current loop, and the differential amplifier is used to acquire the differential voltage across the sampling resistor and output the actual current detection signal. The unlocking control unit compares the actual current detection signal with the temperature-compensated target current signal. Based on the comparison result, it adaptively adjusts the actual duty cycle of the unlocking drive current using PWM to counteract the influence of the real-time ambient temperature on the shape memory alloy phase transformation efficiency of the shape memory metal separation nut (2), and simultaneously suppresses the interference of bus voltage fluctuations on the drive current, ensuring that the actual drive current loaded on the heating element of the shape memory metal separation nut (2) is stable within the rated operating range.

9. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The status feedback module collects the locking and unlocking status signals of the piezoelectric focusing locking automatic unlocking device through a micro displacement sensor and a pressure sensor, and transmits the locking and unlocking status signals to the on-board control system to obtain the feedback working status and fault alarm signals of the piezoelectric focusing locking automatic unlocking device, thereby realizing closed-loop control of the entire unlocking and focusing process. The ground test module includes a special test fixture, which is used to simulate the high and low temperature, vacuum and voltage fluctuation conditions in space to construct a ground simulation test environment. In the ground simulation test environment, the activated memory metal separation nut (2) is removed and replaced with a new memory metal separation nut (2). The preload and position accuracy during locking are accurately reproduced through the precision thread pair on the special test fixture. Then, multiple simulated unlocking actions are performed to verify the consistency of the drive control logic of the unlocking control system under different simulated conditions.

10. The piezoelectric focusing locking automatic unlocking device for a remote sensing camera focal plane circuit box according to claim 1, characterized in that: The piezoelectric motor (4) has submicron-level stepping drive precision. After unlocking, it can accurately drive the focal plane circuit box to move (6) micro-displacement, so as to realize high-precision focusing of the detector (15).

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