A coiled and extended extraterrestrial landing mechanism and its design method

Abstract

This invention relates to a coiled, extendable landing mechanism for extraterrestrial bodies and its design method, belonging to the field of mechanical technology. Compared with traditional landing mechanisms, this invention not only allows for storage in a smaller space before spacecraft launch but also enables deployment along a one-dimensional direction during the deployment process, effectively reducing the envelope of the mechanism's extension motion and improving space utilization. This allows the invention to save space for a single launch mission and install additional payload equipment, improving mission efficiency. Furthermore, this invention improves the design of both the component cross-sectional dimensions and configuration of the coiled extendable arm, effectively reducing weight while ensuring the landing mechanism's load-bearing capacity. The optimization results are obtained through sequential programming rather than manual iterative design modifications, ensuring the validity of the results. Compared to traditional coiled extendable arms, this invention improves bending resistance and ensures the landing mechanism can withstand landing impacts during the landing phase, achieving a safe landing of the probe.

Description

Technical Field

[0001] This invention relates to a coiled, extended extraterrestrial landing mechanism and its design method, belonging to the field of mechanical technology. Background Technology

[0002] Extraterrestrial exploration is of great significance for revealing the origin and evolution of the universe and expanding human understanding of science, technology and life. Landing exploration can achieve in-situ exploration on the surface of extraterrestrial bodies and obtain richer exploration data. It is a common exploration method in deep space exploration missions. Currently, landing exploration can be carried out on celestial bodies such as Mercury, Mars and the Moon in the solar system.

[0003] Soft landing is a crucial step in ensuring the successful completion of extraterrestrial exploration missions. Soft landing typically involves using retro-rockets to decelerate the probe as it approaches the celestial surface. Simultaneously, the probe's guidance, navigation, and control system (GNC) adjusts its attitude and controls its descent speed, allowing it to land on the surface at a sufficiently low velocity. A landing buffer absorbs the energy released upon impact. Currently, commonly used landing buffers are mainly classified into three categories: airbag landing mechanisms, damped landing mechanisms, and deformable landing mechanisms. Each of these buffers has its own drawbacks. For example, airbags are easily punctured by debris on the celestial surface, rendering the buffer ineffective; damped and deformable landing mechanisms are heavy and difficult to compactly store during launch, resulting in low space utilization and a large mechanical response during launch.

[0004] The coiled extendable arm is a lightweight, high-ratio one-dimensional space deployment mechanism. It can be stored in a small space during spacecraft launch using a longitudinal beam-coil mechanism, resulting in high space utilization. Currently, it is commonly used as a support mechanism for equipment such as solar panels and as a gravity gradient rod for satellites. However, conventional coiled extendable arms have poor bending resistance and may be crushed under landing impact loads; therefore, they have not yet been used in the design of landing mechanisms for deep space probes. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a coiled extension extraterrestrial landing mechanism and its design method, which solves the problems of the traditional landing mechanism being too heavy and difficult to compactly store during the launch phase, as well as the poor bending resistance of conventional coiled extension arms.

[0006] The technical solution of this invention is: a coiled, extended extraterrestrial landing mechanism, comprising:

[0007] Mounting bracket, fixedly installed on the detector structure platform;

[0008] The probe features a coiled, bend-resistant extension arm, with one end fixedly connected to a mounting support and the other end connected to a landing pad via a universal joint. Several coiled extension arms are evenly arranged, each comprising several variable-section longitudinal beams and several crossbars. The variable-section longitudinal beams are longitudinal load-bearing components, their cross-sectional dimensions varying axially according to design requirements. The combination of several variable-section longitudinal beams is evenly arranged. The crossbars are fixed at both ends to adjacent variable-section longitudinal beams via hinged joints, providing lateral support for the coiled extension arms. Before launch, the coiled extension arms are placed in a compressed, retracted state using a clamping rod and a pin puller. After launch and before landing on an extraterrestrial body, the pin puller is ignited to unlock the clamping rod, and the coiled extension arms unfold. During landing, the probe absorbs energy through the landing pad.

[0009] The reinforcing boss, with an overall frustum structure, provides root support for the coiled extension arm. Four threaded blind holes are evenly arranged on the bottom surface of the reinforcing boss and are fixedly installed on the mounting bracket. Through holes are provided at the center of the upper and lower bottom surfaces of the reinforcing boss for installing the coiled extension arm. Three threaded through holes are evenly arranged on the side of the reinforcing boss and are used to fix the root of the coiled extension arm. A groove is cut on the top surface of the reinforcing boss according to the shape of the lower end of the hinge joint, for embedding and installing the uppermost hinge joint of the coiled extension arm, thereby strengthening the connection between the coiled extension arm and the mounting bracket, and thus improving the bending resistance of the coiled extension arm.

[0010] Furthermore, the root of the variable cross-section longitudinal beam is thicker than the bottom.

[0011] Furthermore, the number of variable cross-section longitudinal beams is three, arranged in an equilateral triangle pattern, and the spacing between each pair of variable cross-section longitudinal beams is determined according to design requirements.

[0012] Furthermore, every three crossbars form a triangular crossbeam, and there are several layers in total; the crossbar cross-sectional area of ​​each layer of triangular crossbeam is the same, and is determined according to design requirements.

[0013] Furthermore, the spacing between adjacent triangular crossbeams is determined according to design requirements, and all adjacent triangular crossbeams have the same spacing.

[0014] Furthermore, the crossbar becomes thicker closer to the root of the coiled extension arm.

[0015] Furthermore, the two crossbars closest to the bottom and middle of the coiled extension arm are thicker than the crossbars at other locations.

[0016] Furthermore, it also includes diagonal stiffening cables; the diagonal stiffening cables pass through the cable holes on the hinge joint to provide a certain preload for the unfolded coiled extension arm, thereby increasing the stiffness of the coiled extension arm.

[0017] Furthermore, the hinge joint is V-shaped, with a through hole at the lower end in the vertical direction and fixedly connected to the variable cross-section longitudinal beam; and blind holes at both upper ends in the horizontal direction, each fixedly connected to a crossbar.

[0018] A design method for the aforementioned coiled, extended extraterrestrial landing mechanism includes:

[0019] Step 1): Based on the landing conditions of the probe, calculate the force on a single landing mechanism, analyze the moment when the landing mechanism experiences the maximum load during this process, and record the corresponding static load.

[0020] Step 2), give the initial design of the coiled extension arm, establish the corresponding finite element model, and apply the static load recorded in Step 1) onto the finite element model, and record p = 1;

[0021] Step 3): Based on the stress state and the requirements of the landing mechanism for bending resistance and lightweight design, with the goal of minimizing structural weight, and using the fundamental frequency of the landing mechanism when the coiled extension arm is fully deployed, the maximum displacement of the landing foot pad under static load, and the maximum buckling factor as constraints, and with the cross-sectional dimensions of the variable cross-section longitudinal beams and crossbars, as well as the spacing between the variable cross-section longitudinal beams and crossbars, as continuous design variables, an optimization problem model is established:

[0022]

[0023] In the formula, X = {x1, x2, ..., x} m} T And Y = {y1, y2, ..., y n} T Let f(X,Y) and g represent the cross-sectional dimensions of the variable cross-section longitudinal beams and crossbars, and the spacing of the variable cross-section longitudinal beams and crossbars, respectively. j (X,Y) represent the objective function and the j-th constraint function, respectively, where j = 1, ..., J0, and J0 is the number of constraints; and These are the upper and lower limits of the cross-sectional dimension variables, i = 1, ..., m, where m is the number of dimension variables; and These are the upper and lower limits of the spacing variable, k = 1, ..., n, where n is the number of spacing variables;

[0024] Step 4) Use the finite element method to perform structural and sensitivity analysis on the current coiled extension arm design;

[0025] Step 5): Using the structural analysis and sensitivity analysis information obtained above, construct a sequential quadratic approximation problem of the original optimization problem model; in the p-th stage, the approximation problem is:

[0026]

[0027] In the formula, (X p ,Y p f(X) represents the known point in stage p, which is the solution to the approximate problem in the previous stage; d represents the change in the known point in the current stage, and is also the design variable of the approximate problem; p ,Y p ) and g j (X p ,Y p Let be the objective and constraint functions at the known point. and H(X) represents the first-order derivative vectors of the objective and constraint functions at the known points, respectively. p ,Y p Let be the Hessian matrix of the objective function at the known points;

[0028] Step 6): Solve the above approximate problem using the interior point method to obtain the optimal solution d. opt and the currently known point (X) p ,Y p According to d opt Make changes to obtain a new design point (X). p+1 ,Y p+1 );

[0029] Step 7), if the new design point (X) p+1 ,Y p+1 ) and the current point (X) p ,Y p If the distance between the two points (X and X) satisfies the preset distance range and the constraints, then the approximate problem converges, and the new point is the optimal configuration and size design of the coiled extendable arm; otherwise, according to the new point (X... p+1 ,Y p+1 Modify the finite element model, record p = p + 1, and return to step 4) until the approximate problem converges.

[0030] The advantages of this invention compared to the prior art are:

[0031] 1) Compared with traditional landing mechanisms, this invention can be housed in a smaller space before spacecraft launch and can also deploy along a one-dimensional direction during deployment, effectively reducing the envelope of the mechanism's extension motion and improving space utilization. This allows the invention to save space for a single launch mission and install additional payload equipment, thereby improving mission efficiency;

[0032] 2) Compared to conventional coiled extendable arms, this invention improves both the component cross-sectional dimensions and configuration of the coiled extendable arm, effectively reducing weight while maintaining the landing mechanism's load-bearing capacity. The optimization results are obtained through sequential programming rather than manual iterative design modifications, ensuring the validity of the results. Compared to traditional coiled extendable arms, it improves bending resistance and ensures the landing mechanism can withstand landing impacts during the landing phase, achieving a safe landing of the probe. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 This is a diagram showing the state of the probe's spiral-shaped, extended landing mechanism for extraterrestrial objects during the launch phase.

[0035] Figure 2 This is a diagram showing the state of the probe's spiraling, extended landing mechanism for extraterrestrial objects during the landing phase.

[0036] Figure 3 Design flowchart of the core of the landing mechanism—a coiled extendable arm with bending resistance.

[0037] Figure 4 This is a schematic diagram of the overall and partial aspects of a coiled extendable arm with bending resistance.

[0038] Figure 5 To enhance the installation diagram of the boss on the mounting bracket, the coiled extension arm fixed by the reinforcing boss is hidden for ease of display.

[0039] Figure 6 To enhance the structural diagram of the boss.

[0040] In the diagram: 1. Detector structure platform; 2. Mounting support; 3. Reinforcing boss; 4. Coiled extension arm with bending resistance; 5. Universal joint; 6. Landing footpad; 7. Thrust reverser; 41. Variable cross-section longitudinal beam; 42. Crossbar; 43. Diagonal stiffening cable; 44. Hinge joint. Detailed Implementation

[0041] To better understand the above technical solutions, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0042] The following description, in conjunction with the accompanying drawings, provides a more detailed account of a coiled, extended exoplanet landing mechanism and its design method provided by embodiments of the present invention. A specific implementation may include: a coiled, extended exoplanet landing mechanism comprising six landing arms arranged obliquely to maintain the stability of the probe's landing; each landing arm is obtained through a lightweight and bending-resistant optimization design of a conventional coiled extension arm, ensuring that the landing mechanism effectively reduces weight while maintaining load-bearing capacity. The bending-resistant coiled extension arm design is the core of this invention, further improving the bending resistance based on the high deployment-to-retraction ratio of conventional coiled extension arms.

[0043] 1) Mounting support 2 is fixedly connected to the detector structure platform 1. Conventional pull pins and dampers are installed inside to control the locking, releasing and driving of the coiled extension arm.

[0044] 2) The reinforcing boss 3 is connected to the mounting support 2 and has a frustum structure. It is used to strengthen the bending resistance of the root of the coiled extension arm 4.

[0045] 3) A coiled extension arm 4 with bending resistance is fixedly installed on the mounting bracket 2 by a reinforcing boss 3; a conventional clamping rod is fixedly installed on the top of the coiled extension arm 4 and locked by a puller in the mounting bracket 2, so as to clamp and retract the coiled extension arm 4 during the detector launch phase; the clamping rod is also connected to a damper in the mounting bracket 2 by a nylon rope, so as to control the deployment speed of the coiled extension arm 4 by the damper and prevent the deployment speed of the coiled extension arm 4 from being too fast and unstable;

[0046] 4) The landing foot pad 6 is connected to the coiled extension arm 4 via a universal joint 4.

[0047] like Figure 4 The further bending-resistant coiled extension arm 4 mainly includes:

[0048] 1) Variable cross-section longitudinal beam 41

[0049] The variable cross-section longitudinal beam 41 is the longitudinal load-bearing component of the coiled extension arm 4. The cross-sectional shape of the variable cross-section longitudinal beam 41 is circular, and the cross-sectional dimensions vary along the axial direction and are optimized using a sequential programming method. The design trend is that the upper root is thicker and the lower bottom is thinner. The coiled extension arm 4 includes three variable cross-section longitudinal beams 41, arranged in an equilateral triangle. The spacing between each pair of variable cross-section longitudinal beams 41 is optimized using a sequential programming method.

[0050] 2) Crossbar 42

[0051] The crossbar 42 has a circular cross-section and is installed between two adjacent variable cross-section longitudinal beams 41. Three crossbars 42 form a triangular crossbeam, which is fixed to the variable cross-section longitudinal beam 41 via hinge joints 44, thus providing lateral support for the coiled extension arm 4. The crossbars 42 in each layer of the triangular crossbeam have the same cross-sectional dimensions, which are optimized using a sequential programming method. The design trend is that the crossbars 42 closer to the root of the coiled extension arm 4 are thicker, but the two layers of crossbars 42 near the bottom and middle are also thicker. The spacing between adjacent layers of crossbeams is optimized using a sequential programming method; for ease of design, the spacing between all adjacent crossbeams is the same.

[0052] 3) Diagonal stiffening cable 43

[0053] The cable passes through the cable hole on the hinge joint 44 to provide a certain preload for the unfolded coiled extension arm 4, thereby increasing the stiffness of the coiled extension arm 4.

[0054] 4) Hinged joint 44

[0055] The whole is V-shaped, with a vertical through hole at the lower end of the V-shape and fixedly connected to the variable cross-section longitudinal beam 41, and blind holes at the two upper ends of the V-shape and fixedly connected to a crossbar 42.

[0056] By optimizing the cross-sectional dimensions of the variable cross-section longitudinal beam 41 / crossbar 42 and the spacing between the variable cross-section longitudinal beam 41 / crossbar, the following objectives can be achieved: 1) reducing the weight of the coiled extension arm 4; 2) enhancing the bending resistance of the coiled extension arm 4, effectively resisting the bending load during landing, and avoiding the coiled extension arm 4 from being crushed or failing due to bending.

[0057] In the solutions provided in the embodiments of the present invention, such as Figure 1 As shown, the present invention discloses a coiled extensional extraterrestrial landing mechanism comprising: a mounting support 2, a reinforcing boss 3, a coiled extensional arm with bending resistance 4, a universal joint 5, and a landing foot pad 6. The landing mechanism is mounted on the deep space probe structural platform 1. The entire probe may contain several sets of landing mechanisms to maintain the stability of the probe during landing. The specific number can be designed according to the needs of the landing and exploration mission; the example in this paper is 6 sets.

[0058] Each landing mechanism consists of components 2 to 6. The specific installation process is as follows: First, the mounting bracket 2 is installed on the detector structure platform 1. The coiled extension arm 4 is installed on the mounting bracket 2 and its root is reinforced by the reinforcing boss 3. Then, it is pressed and fixed by the clamping rod and the puller. The landing foot pad 6 is installed at the bottom of the coiled extension arm 4 through the universal joint 5.

[0059] The main procedures after the landing mechanism enters orbit are as follows:

[0060] 1) Before the detector is launched, the coiled extension arm 4 is placed in a coiled, retracted state using a clamping rod and a puller, reducing the overall envelope size of the detector and improving the utilization rate of the mounting space, such as... Figure 1 As shown;

[0061] 2) After the probe is launched into orbit and before it lands and descends on an extraterrestrial body, the pin release mechanism is ignited to unlock and release the clamping rod, and the coiled extension arm 4 unfolds, as shown. Figure 2 As shown;

[0062] 3) During the landing phase, the retrorockets are ignited to decelerate the probe and, under the control of the GNC, the probe's attitude is adjusted and the descent speed is controlled. When the probe reaches a certain altitude in front of the moon, the retrorockets are shut off. The probe lands on the surface of the extraterrestrial body through the landing mechanism. During the landing process, the elastic deformation of the landing mechanism and the compression between the footpad and the soil on the surface of the celestial body are used to buffer and absorb energy.

[0063] In this invention, the coiled extendable boom 4 needs to withstand landing impact loads, thus placing new demands on its bending resistance. Therefore, this invention employs... Figure 3 The steps shown illustrate the design of a coiled extendable arm 4 with bending resistance. This design of the coiled extendable arm 4 with bending resistance is the core of this invention. It further enhances bending resistance on top of the high deployment-to-retraction ratio of conventional coiled extendable arms, which is the main feature distinguishing this invention from traditional landing mechanisms and conventional coiled extendable arms.

[0064] This invention employs a structural optimization technique that combines sequential programming and structural analysis in the design of the coiled extension arm 4. The specific design steps are as follows:

[0065] 1) Based on the landing conditions of the probe, calculate the force on a single landing mechanism, analyze the moment when the landing mechanism experiences the maximum load during this process, and record the corresponding static load;

[0066] 2) Give an initial design of the coiled extension arm 4, establish the corresponding finite element model, and apply the static load recorded in step 1) onto the finite element model, and record p = 1;

[0067] 3) Based on the stress state and the requirements of the landing mechanism for bending resistance and lightweight design, a corresponding optimization problem model is established. In this invention, the optimization problem aims at minimizing the structural weight, with constraints including the fundamental frequency of the landing mechanism when the coiled extension arm 4 is fully deployed, the maximum displacement of the landing foot pad 6 under static load, and the maximum buckling factor. The cross-sectional dimensions of the variable cross-section longitudinal beam 41 / crossbar 42 and the spacing between the variable cross-section longitudinal beam 41 / crossbar are used as continuous design variables. The mathematical model of the original optimization problem is shown in equation (1):

[0068]

[0069] In the formula, X = {x1, x2, ..., x} m} T And Y = {y1, y2, ..., y n} T Let f(X,Y) and g represent the cross-sectional dimension variables of the variable cross-section longitudinal beam 41 / crossbar 42 and the spacing variables of the variable cross-section longitudinal beam 41 / crossbar 42, respectively. j (X,Y) represent the objective function and the j-th constraint function (j=1,…,J0), respectively, where J0 is the number of constraints; and These are the upper and lower limits of the cross-sectional dimension variables (i = 1, ..., m), where m is the number of dimension variables; and These are the upper and lower limits of the spacing variables (k = 1, ..., n), where n is the number of spacing variables.

[0070] 4) The current design of the coiled extension arm 4 is subjected to structural and sensitivity analysis using the finite element method;

[0071] 5) Using the structural analysis and sensitivity analysis information obtained above, construct the sequential quadratic approximation problem of the original problem (1). In the p-th stage, the specific form of the approximation problem is shown in equation (2):

[0072]

[0073] In the formula, (X p ,Y p ) represents the known point in stage p, which is the solution to the approximate problem in the previous stage; d represents the change in the known point in the current stage, and is also the design variable of the approximate problem (2); f(X) p ,Y p ) and g j (X p ,Y p Let be the objective and constraint functions at the known point. and H(X) represents the first-order derivative vectors of the objective and constraint functions at known points, and can be obtained through mature structural analysis and sensitivity analysis. p ,Y p The Hessian matrix H(X) of the objective function at known points is usually very difficult to solve. However, in the original problem (1), the change in the spacing between the variable cross-section longitudinal beams 41 and the transverse frame does not actually cause a change in the structural mass (i.e., the objective function). Therefore, in solving the Hessian matrix H(X) of the objective function, the solution is relatively straightforward. p ,Y p When H(X) is obtained, it is only necessary to differentiate with respect to the cross-sectional dimension variable X; at this time, H(X) p ,Y pIt can be expressed in explicit form with respect to X and can be calculated directly;

[0074] 6) Solve the above approximate problem (2) using the interior point method to obtain the optimal solution d. opt and the currently known point (X) p ,Y p According to d opt Make changes to obtain a new design point (X). p+1 ,Y p+1 );

[0075] 7) If the new design point (X) p+1 ,Y p+1 ) and the current point (X) p ,Y p If the distance between the new point (X) and the target point (X) satisfies the preset distance range and the constraints, then the sequence approximation problem converges, and the new point represents the optimal configuration / size design of the coiled extension arm 4; otherwise, based on the new point (X)... p+1 ,Y p+1 Modify the finite element model, record p = p + 1, and return to step 4) until the sequence approximation problem converges.

[0076] The use of structural optimization technology enables the design process of the coiled extension arm 4 to be automated, reducing manual workload and ensuring the validity of the results.

[0077] Through the above optimization design steps, a coiled extendable arm 4 with bending resistance can be obtained. The design trend of the variable cross-section longitudinal beam 41 of this coiled extendable arm 4 is that it is thicker at the upper root and thinner at the lower bottom, so as to reduce weight while ensuring good bending stiffness; the design trend of the crossbar 42 is that the crossbar 42 is thicker closer to the root of the coiled extendable arm 4, but the two layers of crossbar 42 near the bottom and middle are also relatively thick, so as to provide better lateral stiffness for the thinner variable cross-section longitudinal beam 41 at the bottom of the coiled extendable arm 4, while providing good lateral support in the middle of the coiled extendable arm 4.

[0078] To further enhance the bending resistance of the coiled extension arm 4, the root of the coiled extension arm 4 is installed within the reinforcing boss 3 fixed to the mounting support 2, and the uppermost hinge joint 44 of the coiled extension arm 4 is embedded into the upper groove of the reinforcing boss 2, as shown. Figure 5 As shown.

[0079] Strengthen the 3-structure boss, such as Figure 6As shown, the overall shape is a frustum, which ensures that the landing mechanism has good bending resistance at its root under loads in any direction. Four threaded blind holes are evenly drilled on the bottom surface of the reinforcing boss 3, and it is fixed to the mounting support 2 with bolts. Through holes are drilled in the center of the upper and lower bottom surfaces of the reinforcing boss 3 for mounting the coiled extension arm 4. Three threaded through holes are evenly drilled on the side of the reinforcing boss 3, and the root of the coiled extension arm 4 is fixed with fastening bolts. The upper bottom surface of the reinforcing boss 3 is grooved according to the shape of the lower end of the hinge joint 44, which is used to embed and install the uppermost hinge joint 44 of the coiled extension arm 4, thereby strengthening the connection between the coiled extension arm 4 and the mounting support 2, and further improving the bending resistance of the coiled extension arm 4.

[0080] Finite element analysis of the above-mentioned coiled extension arm 4 shows that the newly designed coiled extension arm 4 has good bending resistance, and the overall weight of the landing mechanism can be reduced by more than 25% compared with the traditional landing mechanism, indicating that this design has good advantages.

[0081] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0082] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A coiled, extended extraterrestrial landing mechanism, characterized in that, include: Mounting bracket (2) is fixedly installed on the detector structure platform (1); A coiled extension arm (4) with bending resistance is fixedly connected to a mounting support (2) at one end and connected to a landing pad (6) at the other end via a universal joint (5). Several coiled extension arms (4) are provided and evenly arranged. Each coiled extension arm (4) includes several variable cross-section longitudinal beams (41) and several crossbars (42). The variable cross-section longitudinal beams (41) are longitudinal load-bearing members, and their cross-sectional dimensions change along the axial direction according to design requirements. The combination of several variable cross-section longitudinal beams (41) is uniform. Arrangement; the two ends of the crossbar (42) are fixed to the adjacent variable cross-section longitudinal beam (41) by hinge joints (44) to provide lateral support for the coiled extension arm (4); before the probe is launched, the coiled extension arm (4) is placed in the coiled and retracted state by clamping rod and pin puller; after the probe is launched into orbit and before landing and descending on the extraterrestrial body, the pin puller is ignited to unlock the clamping rod and the coiled extension arm (4) is deployed; during the landing phase of the probe, the probe absorbs energy by landing foot pad (6); The reinforcing boss (3) has a frustum-shaped structure and provides root support for the coiled extension arm (4). Four threaded blind holes are evenly arranged on the bottom surface of the reinforcing boss (3) and fixedly installed on the mounting bracket (2). The center of the upper and lower bottom surfaces of the reinforcing boss (3) is provided with through holes for installing the coiled extension arm (4). Three threaded through holes are evenly arranged on the side of the reinforcing boss (3) and fixed at the root of the coiled extension arm (4). The upper bottom surface of the reinforcing boss (3) is grooved according to the shape of the lower end of the hinge joint (44) for embedding and installing the uppermost hinge joint (44) of the coiled extension arm (4), thereby strengthening the connection between the coiled extension arm (4) and the mounting bracket (2) and improving the bending resistance of the coiled extension arm (4).

2. The coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, The root of the variable cross-section longitudinal beam (41) is thicker than the bottom.

3. The coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, The number of variable cross-section longitudinal beams (41) is three, arranged in an equilateral triangle. The spacing between each pair of variable cross-section longitudinal beams (41) is determined according to design requirements.

4. The coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, Every three crossbars (42) form a triangular crossbeam, and there are several layers in total; the crossbars (42) of each layer of triangular crossbeam have the same cross-sectional area, which is determined according to the design requirements.

5. A coiled, extended extraterrestrial landing mechanism according to claim 4, characterized in that, The spacing between adjacent triangular crossbeams is determined according to design requirements, and all adjacent triangular crossbeams have the same spacing.

6. A coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, The crossbar (42) is thicker the closer it is to the root of the coiled extension arm (4).

7. A coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, The two crossbars (42) closest to the bottom and middle of the coiled extension arm (4) are thicker than the crossbars (42) at other locations.

8. A coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, It also includes a diagonal stiffening cable (43); the diagonal stiffening cable (43) passes through the cable hole on the hinge joint (44) to provide a certain pre-tension force for the unfolded coiled extension arm (4) and increase the stiffness of the coiled extension arm (4).

9. A coiled, extended extraterrestrial landing mechanism according to claim 1, characterized in that, The hinge joint (44) is V-shaped, with a through hole at the lower end in the vertical direction and fixedly connected to the variable cross-section longitudinal beam (41); and blind holes at both upper ends in the horizontal direction, each fixedly connected to a crossbar (42).

10. A design method for a coiled, extended extraterrestrial landing mechanism as described in any one of claims 1 to 9, characterized in that, include: Step 1: Based on the landing conditions of the probe, calculate the force on a single landing mechanism, analyze the moment when the landing mechanism experiences the maximum load during this process, and record the corresponding static load. Step 2, give the initial design of the coiled extension arm (4), establish the corresponding finite element model, and apply the static load recorded in step 1 onto the finite element model, and record p = 1; Step 3: Based on the stress state and the requirements of the landing mechanism for bending resistance and lightweight design, with the goal of minimizing structural weight, and constrained by the fundamental frequency of the landing mechanism when the coiled extension arm (4) is fully deployed, the maximum displacement of the landing foot pad (6) under static load, and the maximum buckling factor, and with the cross-sectional dimensions of the variable cross-section longitudinal beam (41) and crossbar (42) and the spacing of the variable cross-section longitudinal beam (41) and crossbar as continuous design variables, an optimization problem model is established: In the formula, X = {x1, x2, ..., x} m } T And Y = {y1, y2, ..., y n } T The cross-sectional dimensions of the variable cross-section longitudinal beam (41) and crossbar (42) and the spacing of the variable cross-section longitudinal beam (41) and crossbar are respectively f(X,Y) and g. j (X,Y) represent the objective function and the j-th constraint function, respectively, where j = 1, ..., J0, and J0 is the number of constraints; and These are the upper and lower limits of the cross-sectional dimension variables, i = 1, ..., m, where m is the number of dimension variables; and These are the upper and lower limits of the spacing variable, k = 1, ..., n, where n is the number of spacing variables; Step 4: Use the finite element method to perform structural and sensitivity analysis on the current design of the coiled extension arm (4); Step 5: Using the structural analysis and sensitivity analysis information obtained above, construct the sequential quadratic approximation problem of the original optimization problem model; In the p-th stage, the approximate problem is: In the formula, (X p ,Y p f(X) represents the known point in stage p, which is the solution to the approximate problem in the previous stage; d represents the change in the known point in the current stage, and is also the design variable of the approximate problem; p ,Y p ) and g j (X p ,Y p Let be the objective and constraint functions at the known point. and H(X) represents the first-order derivative vectors of the objective and constraint functions at the known points, respectively. p ,Y p Let be the Hessian matrix of the objective function at the known points; Step 6: Solve the above approximate problem using the interior point method to obtain the optimal solution d. opt and the currently known point (X) p ,Y p According to d opt Make changes to obtain a new design point (X). p+1 ,Y p+1 ); Step 7, if the new design point (X) p+1 ,Y p+1 ) and the current point (X) p ,Y p If the distance between the two points satisfies the preset distance range and the constraints, then the approximate problem converges, and the new point is the optimal configuration and size design of the coiled extension arm (4); otherwise, according to the new point (X... p+1 ,Y p+1 Modify the finite element model, record p = p + 1, and return to step 4 until the approximate problem converges.

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