Film microfragment detection device based on photoelectric combination signal identification

Abstract

Aiming at the difficulty in monitoring space debris below centimeter level, the invention provides a thin film microfragment detection technology based on optical signal identification, high-precision positioning and speed measurement of subcentimeter level microfragments are realized through a photoelectric combination mode, and the blank of sustainable microfragment detection in China is filled. The system is composed of a resistance wire detector, an unfolding mechanism, an impact point optical monitor and an on-satellite data processing unit. According to the resistance wire detector, a copper wire resistance net is arranged by adopting a chessboard method, a detection area is divided into smaller detection subareas by transverse and longitudinal blocks which are perpendicular to each other, and when a copper wire is broken due to fragment impact, the resistance value change of the corresponding block triggers level jump, so that fragment impact positioning is realized. The design of an illumination light source and a high-reflection coating is innovatively introduced between the two layers of films, so that impact points on the films can be clearly imaged, then the characteristics of impact holes are extracted through an intelligent image algorithm, and the positioning precision of the impact points of fragments can be improved to be within 1 mm.

Description

Technical Field

[0001] This invention relates to a device for detecting small space debris, which utilizes a combination of photoelectric methods to achieve in-situ space-based detection of space debris and obtain high-precision position and velocity information of the debris. It belongs to the field of aerospace technology. Background Technology

[0002] With the increasing number of satellites in orbit around the Earth, the amount of space debris generated after satellite launches, damage, or disintegration is constantly rising, becoming one of the important factors threatening the safety of spacecraft in orbit. The detection of space debris, especially the detection of tiny debris, has become a major issue in the aerospace industry today.

[0003] Currently, space debris detection methods mainly include non-in-situ detection and space-based in-situ detection. Non-in-situ detection systems are divided into ground-based and space-based systems. Ground-based non-in-situ detection systems are further divided into ground-based photoelectric telescope systems and ground-based radar systems, depending on the type of sensor used. Ground-based photoelectric telescopes are mainly used to detect small targets in low Earth orbit and faint targets in high Earth orbit, while ground-based radars are mainly used to detect large objects in low Earth orbit. Space-based non-in-situ detection systems can be divided into space-based optical sensors and space-based radar. Compared with ground-based non-in-situ detection systems, space-based non-in-situ detection systems are characterized by being unrestricted by deployment location, unaffected by atmospheric attenuation characteristics, and having high detection timeliness. However, currently, both ground-based and space-based non-in-situ detection systems have difficulty detecting space debris smaller than 1 cm.

[0004] For in-situ detection methods, various detectors based on semiconductor, ionization, and piezoelectric principles have been developed and on-orbit tests have been carried out both domestically and internationally.

[0005] Semiconductor detectors function as capacitors in a circuit. By monitoring the voltage pulses triggered when tiny debris strikes a MOS capacitor, the flux of the debris can be measured. Semiconductors are simple in structure, stable in performance, and easy to manufacture and install. Furthermore, they can effectively detect debris at the centimeter or even micrometer scale. However, their simple structure also results in a lack of multi-parameter detection capabilities. Additionally, because these detectors use a traditional material structure of metal gate-silicon dioxide insulating layer-silicon substrate, the inherent rigidity of this structure prevents flexible folding, making them unsuitable for mechanisms requiring flexible deployment and expansion.

[0006] The most common type of ionization detector is the plasma detector. Its detection principle is based on the fact that when debris carrying enormous energy impacts the detector's pure gold target, a plasma cloud is generated on the target. By analyzing the parameters of this plasma cloud, the detector can obtain physical information related to the debris. Ionization detectors can accurately identify tiny space debris within a certain velocity and mass range. The electron cloud generated by the collision can be analyzed not only for the mass and velocity of the space debris but also for its chemical properties. However, ionization detectors have a small detection area and limited detection angle, restricting their detection range and efficiency. Their relatively complex structure increases the difficulty of maintenance and operation. Furthermore, the small detection area results in less debris data, and the complex structure makes installation and commissioning on spacecraft difficult, leading to high maintenance costs.

[0007] Piezoelectric detectors utilize the piezoelectric effect to detect debris. When a tiny piece of debris impacts the detector surface, corresponding charge signals are generated at the electrodes. By processing these charge signals, information such as the velocity, mass, and impact location of the tiny debris can be obtained. Piezoelectric PVDF detectors have advantages such as simple manufacturing, narrow output pulse, short response time, stable temperature performance, and strong radiation resistance. In contrast, piezoelectric ceramic detectors have a large dynamic measurement range, simple structure, and low cost, but they cannot be folded and are easily damaged, making the launch of large-area detection payloads more expensive.

[0008] The existing in-situ detection methods mentioned above generally suffer from drawbacks such as large required volume, high launch cost, and small detectable area because they do not adopt a combined deployable design.

[0009] In response to the huge demand and research and application value in the field of space debris detection, this invention proposes a space-based deployable in-situ debris detection device based on photoelectric combination. It has a large detection area, can detect sub-centimeter-sized debris, and accurately measures the location, velocity and size information of debris. Summary of the Invention

[0010] (I) Purpose of the Invention

[0011] The cumulative impact effects of space debris smaller than centimeters pose a serious threat to my country's space station. After operating in orbit for some time, the space station has already shown early signs of damage from micro-debris impacts, necessitating strengthened research into countermeasures. However, long-term monitoring data on micro-debris in the orbit of my country's space station is still lacking, and traditional detection methods are ineffective in detecting these tiny fragments. There is an urgent need to develop new detection methods to fill this data gap. To address the challenge of effectively monitoring and collecting data on micro-debris smaller than centimeters, this invention develops a thin-film micro-debris detection device based on photoelectric combined signal recognition. Using a cooperative satellite as a platform, it collects data on micro-sized space debris, filling the gap in my country's data on space debris smaller than 1 cm.

[0012] (II) Technical Solution

[0013] The thin-film micro-fragmentation detection device consists of a resistance wire detector, a double-layer thin-film deployment mechanism, an on-board data processing unit, and an impact point optical monitor.

[0014] A resistance wire detector can be broken down into a polyimide film, a copper wire resistor mesh, and a reinforcing plate. The components of a resistance wire detector are as follows: Figure 1 As shown. The copper wire resistance mesh adopts a checkerboard-style block layout design. By arranging block areas horizontally and vertically on both sides of the film, precise detection of the impact position is achieved. The resistance wire detector has a 5-layer structure. The middle and outermost layers are polyimide films. The front and back of the middle layer film are distributed with 16 horizontal and vertical blocks in a checkerboard pattern, dividing the area into 36 small sections. Before a debris impact, the resistance wire in each block is connected in parallel with a fixed resistor, which is short-circuited by the resistance wire. When an external debris impacts a point on the film, the resistance wire in the horizontal and vertical block containing that point will break, the corresponding fixed resistor will be unshort-circuited, and the potential difference between the two ends will increase. After signal processing, the circuit outputs a standard level transition. By monitoring this signal, the specific location of the debris impact can be accurately located, and the impact time and the time difference between the debris passing through the double-layer film can be obtained. The resistance wire detector has an interface including an electrical interface and a mechanical interface. The electrical interface is connected to the PCB via gold fingers, and the mechanical interface is connected to the unfolding mechanism via reinforcing PI and screws and nuts.

[0015] The unfolding mechanism consists of an unfolding plate, hinges, a locking-releasing device (i.e., a hot knife), etc. Figure 2As shown. The deployment plate is designed as a rectangle: before deployment, the two plates are closed, and after deployment, they form an isosceles right-angled triangle, allowing for a larger area to detect debris; weight-reducing holes are provided on the plate to maintain its lightweight nature. The deployment plate is connected to the satellite bulkhead via side mounting lugs; the two deployment plates are connected by a pair of hinges. The round and square holes in the middle and lower center of the deployment plate are for mounting the hot knife. The elongated hole at the bottom of the base plate is for the gold fingers to pass through the thin film, connecting it to the circuitry. Hinges with torsion springs are used to connect the two deployment plates. During deployment, the deployment plate relies on a locking-release device for rapid deployment, which consists of a hot knife and a pressure block.

[0016] The impact point optical monitor consists of an illumination source and a monitoring camera, capable of imaging the unfolded thin film and identifying the coordinates and size of impact points. The illumination source illuminates the impact holes during camera exposure, ensuring clear imaging of impact points on the thin film. The camera images the unfolded thin film in real time during operation and transmits the images to an image processing unit to monitor the film's state and identify impact points. By appropriately modulating the illumination source to flash at specific power and frequency, the optical characteristics of minute impact points are significantly enhanced, resulting in clear imaging. Figure 2 As shown, the deployable thin-film micro-fragment impact sensing payload utilizes illumination-assisted optical imaging to simultaneously determine the size and location of impacting fragments. An illumination source is installed between two thin films; the outer film is covered with a black coating, and the inner film with a high-reflectivity coating. When a fragment impacts, the film is damaged, causing localized damage. Based on the images transmitted from the camera, an intelligent target recognition algorithm effectively improves the payload's ability to monitor the impact location of small fragments, achieving a positioning accuracy better than 1 mm.

[0017] The onboard data processing unit acquires valid debris information from the resistance wire detector, then sends imaging commands to the impact point optical monitor to obtain images of the thin film after the debris impact. All information is written into a data packet and transmitted to the satellite, which then relays it to the ground. The onboard data processing unit consists of a power module, a microcontroller unit, a position determination module, a time determination module, an image recognition module, and an interface storage module, comprising six types of hardware modules across two printed circuit boards. The power module provides power to the other modules. The position determination and time determination modules process the signals received by the resistance wire detector. The microcontroller unit, powered by the power module, acquires debris information from the position and time determination modules and sends imaging commands to the camera module, interacting with the space station through the interface storage module. The image processing module acquires images captured by the camera, accurately identifies the impact point location using intelligent algorithms, and further obtains its coordinates and size, thus obtaining the debris's velocity and position vectors. The results are then packaged and transmitted to the higher-level unit, while simultaneously determining the specific state of the unfolded thin film.

[0018] (III) Advantages

[0019] The advantages of the thin-film micro-fragment detection device based on photoelectric combined signal recognition of the present invention are as follows:

[0020] ①The thin-film micro-fragment detection device proposed in this invention is lightweight, small in size, and has a large unfolding-to-fold ratio, enabling one-time orbit determination of small space fragments at low cost.

[0021] ② The checkerboard layout proposed in this invention greatly improves space utilization and data acquisition flexibility. The checkerboard layout not only optimizes the detector structure, allowing for a more compact arrangement of detection units on the thin-film surface, but also enhances the detection capability for minute debris. Through reasonable channel allocation and area division, the system exhibits high accuracy and stability in the capture and localization of space debris.

[0022] ③ The thin-film micro-fragmentation detection device utilizes autonomous illumination-assisted optical imaging to post-impact extract the accurate size and location of the impact hole. This method significantly reduces the dependence of positioning accuracy on camera resolution and effectively improves the detection accuracy of fragment impact location and velocity. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a resistance wire detector.

[0024] Figure 2 This is a hardware schematic diagram of the thin-film micro-fragment detection device of the present invention: 1-expansion plate, 2-support, 3-resistance wire detector, 4-hot knife, 5-hinge, 6-light source board, 7-light source driver board, 8-core board, 9-camera. Detailed Implementation

[0025] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings to enable those skilled in the art to better understand and implement the present invention. The following examples are merely illustrative and should not be construed as limiting the present invention to the exemplary instances described herein.

[0026] The unfolding plate 1 is connected to the bracket 2 via eight mounting lugs on its side. Initially, the resistance wire detector 3 is folded and fixed between the unfolding plates. One end of the polyethylene (PE) wire is connected to a spring via the resistance block of the hot knife 4, and the other end passes through a pressure block and connects to the other side of the unfolding plate. When the hot knife device receives the unfolding command, the resistor is energized, generating heat sufficient to burn through the PE wire within 2 seconds. After the PE wire breaks, the unfolding mechanism releases its locking state, releasing the tension stored in the torsion spring of the hinge 5. Under the action of the torsion spring, the unfolding plate rapidly unfolds the resistance wire detector, maintaining a fully unfolded state throughout subsequent debris detection tasks. The hinge has a limiting device that allows the unfolding plate to remain at a right angle after unfolding, effectively maintaining the posture stability of the unfolding mechanism.

[0027] Figure 1 The image shows channels 1-8 of the copper wire layer on the front, and similarly, channels 9-16 on the back. Two connected areas form a partition, ensuring each partition contains 4 or 5 smaller partitions, effectively stabilizing the number of fragments the mechanism can detect. Within each partition, high-density copper wires with a line width and spacing of 0.2mm are arranged. When an external fragment impacts a point on the film, the copper wires within the corresponding horizontal and vertical partitions break, causing an increase in resistance in these two partitions. This results in a standard level transition in the circuit output. By monitoring this signal, the specific location of the fragment impact and the impact time can be accurately determined.

[0028] The thin-film micro-fragmentation detection device also utilizes autonomous illumination-assisted optical imaging to further extract the accurate size and location of impact holes post-incidentally. The light source driver board and the core board integrating the main control chip and image processing unit are designed as a single unit in terms of structure and thermal control, and are all mounted in a single circuit control box. For example... Figure 2 As shown, the illumination source consists of an external light source board 6 and a light source driver board 7 inside the circuit control box. Power is supplied by the overall load system, and controlled lighting and extinguishing are achieved through internal constant current and driver modules. The illumination source uses a 120° divergence angle infrared laser light board, controlled by pulse signals to illuminate the unfolded film during camera imaging. Images captured by the camera are transmitted back to the image processing unit via an image bus. The image processing unit is integrated with the main control chip on the core board 8. The image processing module acquires images captured by the camera 9, accurately identifies the impact point location using intelligent algorithms, and further obtains its coordinates and size, thereby obtaining the velocity and position vectors of the fragments. The results are then packaged and transmitted to the upper-level unit, while simultaneously determining the specific state of the unfolded film.

Claims

1. A thin-film micro-fragment detection technology based on optical signal recognition, characterized in that: The detection method mainly includes a resistance wire detector, an impact point optical monitor, and an on-board data processing unit. The impact point optical monitor includes a light source board, a light source driver board, and a camera. The resistance wire detector generates an electrical signal after being penetrated by debris, which is used to identify the location and time of the debris penetration. The impact point optical monitor uses autonomous illumination-assisted optical imaging to extract the accurate size and location of the impact hole after the event, and at the same time determine the specific condition of the thin film; the on-board data processing unit obtains data and image information of effective debris from the resistance wire detector and the impact point optical monitor, writes all the information into a data packet and transmits it to the satellite, and then the satellite transmits it down to the ground.

2. The resistance wire detector according to claim 1, characterized in that: The device has a five-layer structure, consisting of three layers of polyimide film and two layers of copper wire resistive mesh. The middle and outermost layers are polyimide film, with mutually perpendicular horizontal and vertical blocks arranged in a checkerboard pattern on both sides of the middle layer. Before a debris impact, the resistive wires in each block are connected in parallel with a fixed resistor, which is short-circuited by the wires. When an external debris impacts a point on the film, the resistive wires in the corresponding horizontal and vertical blocks break, the corresponding fixed resistors are unshort-circuited, and the potential difference between the two ends increases. After signal processing, the circuit outputs a standard level transition. By monitoring this signal, the specific location of the debris impact can be accurately located, and the impact time and the time difference between the impact and the debris passing through the two layers of film can be obtained. Once the onboard data processing unit receives a valid debris signal from the resistive wire detector, it sends an imaging command to the optical monitor at the impact point, thereby effectively reducing energy consumption and the amount of data transmitted.

3. The impact point optical monitor according to claim 1, characterized in that: An illumination source is used to illuminate the impact holes during camera exposure to ensure that the impact points on the film are clearly imaged. The camera images the film in real time during operation and transmits the images to an image processing unit to monitor the film's condition and identify the impact points. The outer side of the thin film is covered with a black coating, while the inner side is covered with a high-reflectivity coating. By rationally modulating the illumination source to flash at a specific power and frequency, the optical characteristics of the tiny impact points are significantly enhanced, resulting in clear imaging. Based on the images transmitted from the camera, an intelligent target recognition algorithm can effectively improve the load's ability to monitor the impact location of tiny fragments, achieving a positioning accuracy better than 1 mm.

Images