A self-leveling water outlet experimental device and method capable of realizing roll and pitch simulation

Abstract

This invention proposes a self-leveling water-launching experimental device and method capable of simulating roll and pitch, relating to the field of underwater launch technology for aircraft. It solves the problems of existing experimental devices easily causing structural failure or platform instability when subjected to sudden loads upon launch, and the inability to achieve autonomous leveling and simulate roll or pitch scenarios. It includes a water tank, a scissor-type hydraulic lift, a placement platform, and a roll / pitch simulation component. The scissor-type hydraulic lift includes a connected hydraulic telescopic rod and a scissor arm. The placement platform is mounted on the top of the scissor arm and has four telescopic pins. The roll / pitch simulation component includes multiple hydraulic telescopic rods, a ring frame, and a frame lifting mechanism. The ring frame has insertion holes that mate with the telescopic pins. The multiple hydraulic telescopic rods drive the placement platform to reciprocate around a pair of opposing telescopic pins, with the rotation range within the deformation range of the scissor arm and without interference. It is mainly used for underwater launch experiments.

Description

Technical Field

[0001] This invention relates to the field of underwater launch technology for aircraft, and in particular to a self-leveling water-emerging experimental device and method capable of simulating roll and pitch. Background Technology

[0002] With the increasing depletion of land resources, humanity is placing greater emphasis on the exploration and development of unique environments such as the ocean and polar regions. As a crucial platform for deep-sea exploration and resource discovery, the reliable deployment and recovery technology of underwater vehicles is paramount. Experimental research is an important method for studying the underwater launch of these vehicles.

[0003] However, in actual underwater launch processes, the platform experiences a massive instantaneous load upon exiting the launch tube, causing platform swaying and even damage to the launch structure. Furthermore, during actual underwater launches, the launch vehicle encounters unstable factors such as rolling and pitching in complex water conditions. Current experimental devices are not adequately designed to account for these factors, specifically manifested in the following ways: 1. The lifting mechanism of the existing experimental device launch platform mostly adopts a combination structure of steel wire rope and pulley, which relies on manual or motor drive. The launch platform lacks effective support or is rigidly connected to the moving module, which makes it impossible to maintain the stability of the platform during launch. Especially when subjected to sudden load at the moment of launch, it is easy to cause structural failure or platform instability. In addition, the steel wire rope material has insufficient corrosion resistance in seawater environment, which limits its long-term reliable use.

[0004] 2. The existing experimental device does not adequately consider the environmental impact of complex sea conditions. Faced with diverse marine working conditions and complex launch attitude requirements, the existing experimental device lacks a certain degree of accuracy in controlling and adjusting the launch platform when conducting underwater launch experiments, and cannot achieve autonomous leveling and simulate the roll or pitch scenarios in real launches. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a self-leveling water-launching experimental device and method capable of simulating roll and pitch. It employs a scissor-type hydraulic lift as the lifting mechanism, providing reliable support and absorbing the impact load during launch. By incorporating a telescopic pin on the placement platform that engages with a hole on the annular frame, a rotation axis is established to simulate roll or pitch. A hydraulic telescopic rod drives the placement platform to reciprocate around this axis, simulating the roll or pitch conditions experienced by the launch platform during actual launches due to sea conditions. This facilitates richer experimental research on underwater launch technology for vehicles.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a self-leveling water discharge experimental device capable of simulating lateral and longitudinal roll, comprising a water tank, a scissor-type hydraulic lift, a placement platform, and a lateral and longitudinal roll simulation component; The water tank is used to fill experimental seawater; The scissor lift is arranged in a water tank and includes a hydraulic telescopic rod and a scissor arm connected together. The bottom end of the scissor arm is connected to the bottom surface of the water tank. The placement platform is installed on the top of the scissor arm and is equipped with a level sensor. The placement platform has four telescopic pins arranged in a diamond shape at the four corners and facing outwards from the diamond. The lateral and longitudinal rocking simulation component includes multiple hydraulic telescopic rods, a ring frame, and a frame lifting mechanism. The bottom ends of the multiple hydraulic telescopic rods are vertically connected to the bottom surface of the water tank, and the top ends are movably connected to the placement platform. The multiple hydraulic telescopic rods drive the placement platform to reciprocate around a pair of opposing telescopic pins, and the rotation range is within the deformation range of the scissor arm, without interfering with each other. The ring frame is fitted around the outer periphery of the placement platform and has four insertion holes that cooperate with the telescopic pins. The frame lifting mechanism drives the ring frame to move in a direction perpendicular to the bottom surface of the water tank.

[0007] Furthermore, both the hydraulic telescopic rod one and the hydraulic telescopic rod two use a seawater hydraulic system, with experimental seawater as the medium.

[0008] Furthermore, the seawater hydraulic system is equipped with a density sensor and a viscosity sensor to monitor water conditions in real time and adjust the pressurization of hydraulic telescopic rod one and hydraulic telescopic rod two. The hydraulic telescopic rod two is equipped with a magnetostrictive sensor to detect the displacement of the hydraulic telescopic rod two.

[0009] Furthermore, the frame lifting mechanism includes a lead screw and a motor. The lead screws are a pair, symmetrically arranged on both sides of the placement platform. The annular frame is connected to the lead screws to form a planetary roller lead screw pair. The bottom end of the lead screw is perpendicularly connected to the bottom surface of the water tank. The motor drives the lead screw to rotate relative to the water tank, causing the annular frame to move along the axial direction of the lead screw.

[0010] Furthermore, there are four hydraulic telescopic rods arranged in a rectangular quadrant. The top of each hydraulic telescopic rod is connected to the placement platform via a ball joint. A rotating shaft lip seal is provided at the connection between the annular frame and the lead screw. The rotating shaft lip seal is made of fluororubber. Both ends of the lead screw are equipped with stroke limiters.

[0011] Furthermore, the side wall of the water tank is provided with a glass viewing window.

[0012] Furthermore, the inner walls of the telescopic sleeves of both the first and second hydraulic telescopic rods are coated with PTFE, and the valve cores are both ceramic valve cores.

[0013] Furthermore, the telescopic pin is an electrically operated telescopic pin.

[0014] Furthermore, the placement platform is square and equipped with protective corners made of neoprene rubber.

[0015] A method for simulating the roll and pitch of a water discharge experiment, using the aforementioned self-leveling water discharge experiment device capable of simulating roll and pitch, specifically includes the following steps: S1. Fill the water tank with experimental seawater; S2. Start the hydraulic telescopic rod to drive the scissor arm to move, lift the placement platform to the predetermined height, and then lock the hydraulic telescopic rod. S3. Based on the parameters of the level sensor, control the hydraulic telescopic rod two to adjust the placement platform to a level position; S4. Start the frame lifting mechanism to drive the ring frame to rise until the telescopic pin is at the same height as the insertion hole, then close the frame lifting mechanism. S5. Control the pair of telescopic pins to assemble with the insertion holes, and then control the hydraulic telescopic rod to drive the placement platform to reciprocate around the pair of telescopic pins assembled with the insertion holes, thereby simulating the lateral or longitudinal roll of the placement platform.

[0016] Compared with the prior art, the beneficial effects of the self-leveling water discharge experimental device and method for simulating horizontal and vertical rolling as described in this invention are: 1. This invention employs a scissor lift as the lifting mechanism for the placement platform. The scissor lift includes a connected hydraulic telescopic rod and a scissor arm. The hydraulic telescopic rod drives the scissor arm to raise the placement platform to a predetermined height, and then the hydraulic telescopic rod is locked. When a launch mission is performed on the placement platform, the impact load generated by the launch is rapidly dispersed to multiple connecting hinge points and support rods within the scissor arm, effectively absorbed and buffered, avoiding stress concentration, providing reliable support, and solving the problem of structural failure or platform instability caused by impact loads.

[0017] 2. The scissor lift is not a completely rigid structure and will deform under external forces. Therefore, in the experimental seawater environment, the scissor lift cannot guarantee that the placement platform is level when it is raised due to the influence of seawater. Therefore, this invention is equipped with a level sensor on the placement platform. Based on the parameters of the level sensor, the hydraulic telescopic rod II is adjusted to achieve autonomous leveling of the placement platform.

[0018] 3. This invention utilizes the deformation characteristics of the scissor arm structure to control the assembly of a pair of telescopic pins and sockets, which serve as a rotation axis to simulate roll or pitch. Then, the platform is driven by a hydraulic telescopic rod to reciprocate around the rotation axis within the deformation range of the scissor arm structure, thereby simulating the roll or pitch scenario in a real launch.

[0019] 4. This invention uses a seawater hydraulic system to extract seawater from the experimental environment as the medium. This not only reduces the impact of hydraulic oil leakage on experimental observations and the corrosion of experimental equipment by hydraulic oil, but also significantly reduces experimental costs. It has the advantages of safety, reliability, and low cost. Furthermore, the seawater hydraulic system described in this invention is equipped with density and viscosity sensors for real-time monitoring of water conditions. When using different experimental seawater to simulate different sea conditions, it can also precisely adjust the pressurization of hydraulic telescopic rod one and hydraulic telescopic rod two.

[0020] 5. The lead screw of the present invention is provided with stroke limiters at both ends to ensure that the displacement of the ring frame is within a reasonable range and to prevent it from overshooting or over-adjusting.

[0021] 6. The side wall of the water tank of the present invention is provided with a glass window, which can be used to photograph and illuminate the inside of the water tank. Observation and image recording are convenient and clear image information can be easily obtained. Moreover, there is no need to seal and waterproof the camera and lighting equipment. The operation is convenient and greatly improves the experimental efficiency.

[0022] 7. The placement platform described in this invention is equipped with protective corners made of neoprene rubber. When performing horizontal and vertical roll simulations or launching, the placement platform will shake to a certain extent, which may cause the placement platform and the inner wall of the water tank to collide directly. The protective corners play a protective role when the two collide. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of a self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking, as described in this invention. Figure 2 This is a schematic diagram of the internal structure of a self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking, as described in this invention. Figure 3 This is a schematic diagram of the scissor lift and placement platform described in this invention; Figure 4 This is a top view of the placement platform described in this invention; Figure 5 This is a bottom view of the placement platform described in this invention; Figure 6 This is a schematic diagram of the structure of the roll and pitch simulation component described in this invention; Figure 7 This is a front view of the water tank described in this invention; In the diagram: 1-Water tank; 2-Scissor lift; 3-Placement platform; 4-Horizontal and vertical rocking simulation component; 11-Glass window; 21-Hydraulic telescopic rod one; 22-Scissor arm; 31-Telescopic pin; 32-Protective corner; 41-Hydraulic telescopic rod two; 42-Ring frame; 43-Lead screw; 411-Spherical joint seat; 421-Socket; 431-Travel limiter. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0025] I. Detailed Implementation Method 1, see [link / reference] Figure 1-7 This embodiment describes a self-leveling water discharge experimental device capable of simulating lateral and longitudinal rolls, comprising a water tank 1, a scissor-type hydraulic lift 2, a placement platform 3, and a lateral and longitudinal roll simulation component 4. The water tank 1 is used to fill experimental seawater; The scissor-type hydraulic lift 2 is arranged in the water tank 1. It includes a hydraulic telescopic rod 21 and a scissor arm 22 connected to each other. There are two hydraulic telescopic rods 21. One side of the bottom end of the scissor arm 22 is fixedly connected to the bottom surface of the water tank 1, and the other side is slidably connected to the bottom surface of the water tank 1. The scissor arm 22 is composed of multiple X-shaped cross arms hinged together to form a telescopic truss. The placement platform 3 is installed at the top of the scissor arm 22 for vertical launch of the aircraft. The bottom of the placement platform 3 is provided with four telescopic pins 31 arranged in a diamond shape and facing outwards. The four telescopic pins 31 are located on the same horizontal plane. A horizontal sensor is provided at the center of the square at the bottom of the placement platform 3. The horizontal and vertical rocking simulation component 4 includes multiple hydraulic telescopic rods 41, an annular frame 42, and a frame lifting mechanism. The bottom ends of the multiple hydraulic telescopic rods 41 are vertically connected to the bottom surface of the water tank 1, and the top ends are movably connected to the placement platform 3. The multiple hydraulic telescopic rods 41 drive the placement platform 3 to reciprocate around a pair of opposing telescopic pins 31, and the rotation range is within the deformation range of the scissor arm 22, without interfering with each other. The annular frame 42 is sleeved on the outer periphery of the placement platform 3 and has four insertion holes 421 that cooperate with the telescopic pins 31. The frame lifting mechanism drives the annular frame 42 to move in a direction perpendicular to the bottom surface of the water tank 1.

[0026] Preferably, both the first hydraulic telescopic rod 21 and the second hydraulic telescopic rod 41 use a seawater hydraulic system, with experimental seawater as the medium. The seawater hydraulic system, with experimental seawater as the medium, includes multiple liquid medium delivery pipes and multiple liquid medium pumping devices. One end of each liquid medium delivery pipe is connected to either the first hydraulic telescopic rod 21 or the second hydraulic telescopic rod 41, and the other end is connected to the liquid medium delivery pipe. The multiple liquid medium pumping devices consist of six pumps of the same model.

[0027] Preferably, the seawater hydraulic system is equipped with a density sensor and a viscosity sensor for real-time monitoring of water conditions to adjust the pressurization of hydraulic telescopic rod 21 and hydraulic telescopic rod 41. The hydraulic telescopic rod 41 is a four-section hydraulic telescopic rod, and a high-precision magnetostrictive sensor is installed inside the hydraulic telescopic rod 41 to detect the displacement of the hydraulic telescopic rod 41 and ensure that the stroke of the four hydraulic telescopic rods 41 is consistent.

[0028] Preferably, the frame lifting mechanism includes a lead screw 43 and a motor. The lead screw 43 is a pair, symmetrically arranged on both sides of the placement platform 3. The annular frame 42 is connected to the lead screw 43 to form a planetary roller lead screw pair. The bottom end of the lead screw 43 is perpendicularly connected to the bottom surface of the water tank 1. Each lead screw 43 is driven by an asynchronous servo motor of the same model, which drives the lead screw 43 to rotate relative to the water tank 1, thereby causing the annular frame 42 to move along the axial direction of the lead screw 43.

[0029] Preferably, there are four hydraulic telescopic rods 41 arranged in a rectangular quadrant. The top of each hydraulic telescopic rod 41 is connected to the placement platform 3 via a ball joint 411. The projections of the two straight lines containing the diagonals of the rhombus onto the bottom surface of the water tank 1 coincide with the projections of the two straight lines containing the center lines of the rectangle onto the bottom surface of the water tank 1. A rotary shaft lip seal is provided at the connection between the annular frame 42 and the lead screw 43. The rotary shaft lip seal is made of fluororubber to ensure its waterproof sealing. Sealing boxes are provided at both ends of the lead screw 43, and a travel limiter 431 is provided inside the sealing box. The annular frame 42 is rectangular.

[0030] Preferably, the side wall of the water tank 1 is provided with a glass window 11, and the water tank 1 is a square water tank.

[0031] Preferably, the inner walls of the telescopic sleeves of both the hydraulic telescopic rod 21 and the hydraulic telescopic rod 41 are coated with PTFE (polytetrafluoroethylene), and the valve cores are both ceramic valve cores.

[0032] Preferably, the telescopic pin 31 is an electric telescopic pin driven by a separate drive motor. The telescopic pin 31 is made of 17-4PH (H1150 state) stainless steel, which has sufficient strength to withstand the impact load during launch.

[0033] Preferably, the placement platform 3 is square and equipped with protective corners 32 made of neoprene rubber. A slide rail can be installed on the placement platform, and a speed plate (a movable platform connected to the slide rail) is connected to the slide rail to simulate a launch scenario with lateral velocity.

[0034] Preferably, a pair of telescopic pins 31 perpendicular to a pair of lead screws 43 serve as the rotation axis for simulating pitch, with pitch simulation not exceeding 5°, and another pair of telescopic pins 31 serve as the rotation axis for simulating roll, with roll simulation not exceeding 10°.

[0035] Preferably, the self-leveling water discharge experimental device for simulating horizontal and vertical rocking according to the present invention is further equipped with a control cabinet. The liquid medium pumping device, the asynchronous servo motor of the same model belonging to the lead screw 43, and the electric telescopic pin are all connected to the control cabinet, and the entire experimental device is directly controlled by the control cabinet to complete the experiment.

[0036] The working principle of the self-leveling water discharge experimental device for simulating lateral and longitudinal rocking, as described in this invention, is as follows: After the water tank 1 is filled with sufficient experimental seawater, the hydraulic telescopic rod 21 drives the scissor arm 22 to lift the placement platform 3 to the target height. However, due to the influence of the experimental seawater environment, the scissor arm 22 will deform, causing the placement platform 3 at its top to not be completely horizontal. At this time, using the parameters of the level sensor, the four hydraulic telescopic rods 41 are controlled to adjust the placement platform 3 to be completely horizontal, and then the device is driven by a motor. The moving screw 43 rotates, causing the ring frame 42 to rise until the telescopic pin 31 is at the same height as the insertion hole 421. Then, it controls the opposite pair of telescopic pins 31 to assemble with the insertion hole 421. Taking the pair of telescopic pins 31 assembled with the insertion hole 421 as the boundary, the four hydraulic telescopic rods 41 are divided into two groups. The tops of the two groups of hydraulic telescopic rods 41 are controlled to reciprocate in opposite directions, and the rotation range is within the deformation range of the scissor arm 22. During the rotation, the placement platform 3 and the scissor arm 22 do not interfere with each other, realizing the simulation of the lateral or longitudinal sway of the placement platform 3.

[0037] A method for simulating the roll and pitch of a water discharge experiment, using the aforementioned self-leveling water discharge experiment device capable of simulating roll and pitch, specifically includes the following steps: S1. Fill the water tank 1 with sufficient experimental seawater to ensure that the platform 3 is always below the water surface during the experiment. At this time, both hydraulic telescopic rod 21 and hydraulic telescopic rod 41 are in the depressurization state, and both telescopic pins 31 are in the retracted state. S2. Start the hydraulic telescopic rod 21 to drive the scissor arm 22 to move, lift the placement platform 3 to the predetermined height, and then lock the hydraulic telescopic rod 21. S3. Based on the parameters of the horizontal sensor, control the hydraulic telescopic rod 41 to adjust the placement platform 3 to a horizontal position, in preparation for lateral and longitudinal sway simulation. S4. Start the frame lifting mechanism to drive the ring frame 42 to rise until the telescopic pin 31 is at the same height as the insertion hole 421, then close the frame lifting mechanism 43. S5. Control the assembly of a pair of telescopic pins 31 with the insertion hole 421, and then control the hydraulic telescopic rod 41 to drive the placement platform 3 to reciprocate around the pair of telescopic pins 31 assembled with the insertion hole 421, thereby simulating the lateral or longitudinal roll of the placement platform 3.

[0038] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking, characterized in that, It includes a water tank (1), a scissor lift (2), a placement platform (3), and a yaw simulation component (4); The water tank (1) is used to fill experimental seawater; The scissor lift (2) is arranged in the water tank (1). It includes a hydraulic telescopic rod (21) and a scissor arm (22) connected together. The bottom end of the scissor arm (22) is connected to the bottom surface of the water tank (1). The placement platform (3) is installed on the top of the scissor arm (22) and is equipped with a horizontal sensor. The placement platform (3) is provided with four telescopic pins (31) arranged in a rhombus shape and facing outwards from the rhombus. The horizontal and vertical rocking simulation component (4) includes multiple hydraulic telescopic rods (41), an annular frame (42), and a frame lifting mechanism. The bottom end of the multiple hydraulic telescopic rods (41) is vertically connected to the bottom surface of the water tank (1), and the top end is movably connected to the placement platform (3). The multiple hydraulic telescopic rods (41) drive the placement platform (3) to reciprocate around a pair of opposing telescopic pins (31), and the rotation range is within the deformation range of the scissor arm (22), without interfering with each other. The annular frame (42) is sleeved on the outer periphery of the placement platform (3) and is provided with four insertion holes (421) that cooperate with the telescopic pins (31). The frame lifting mechanism drives the annular frame (42) to move in a direction perpendicular to the bottom surface of the water tank (1).

2. The self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking as described in claim 1, characterized in that, Both the hydraulic telescopic rod one (21) and the hydraulic telescopic rod two (41) use a seawater hydraulic system, with experimental seawater as the medium.

3. The self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking according to claim 2, characterized in that, The seawater hydraulic system is equipped with a density sensor and a viscosity sensor to monitor the water conditions in real time and adjust the pressurization of the first hydraulic telescopic rod (21) and the second hydraulic telescopic rod (41). The second hydraulic telescopic rod (41) is equipped with a magnetostrictive sensor to detect the displacement of the second hydraulic telescopic rod (41).

4. The self-leveling water discharge experimental device capable of simulating horizontal and vertical rolling as described in claim 1, characterized in that, The frame lifting mechanism includes a lead screw (43) and a motor. The lead screw (43) is a pair, symmetrically arranged on both sides of the placement platform (3). The annular frame (42) is connected to the lead screw (43) to form a planetary roller lead screw pair. The bottom end of the lead screw (43) is vertically connected to the bottom surface of the water tank (1). The motor drives the lead screw (43) to rotate relative to the water tank (1), thereby driving the annular horizontal frame (42) to move along the axial direction of the lead screw (43).

5. The self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking according to claim 1, characterized in that, The hydraulic telescopic rods (41) consist of four rods arranged in a rectangular quadrant. The top of each hydraulic telescopic rod (41) is connected to the placement platform (3) via a ball joint (411). A rotating shaft lip seal is provided at the connection between the annular frame (42) and the lead screw (43). The rotating shaft lip seal is made of fluororubber. Both ends of the lead screw (43) are provided with stroke limiters (431).

6. The self-leveling water discharge experimental device capable of simulating horizontal and vertical rolling as described in claim 1, characterized in that, The side wall of the water tank (1) is provided with a glass viewing window (11).

7. The self-leveling water discharge experimental device capable of simulating horizontal and vertical rocking according to claim 1, characterized in that, The inner walls of the telescopic sleeves of both the first (21) and the second (41) hydraulic telescopic rods are coated with PTFE, and the valve cores are ceramic valve cores.

8. The self-leveling water discharge experimental device for simulating horizontal and vertical rolling as described in claim 1, characterized in that, The telescopic pin (31) is an electrically operated telescopic pin.

9. The self-leveling water discharge experimental device for simulating horizontal and vertical rocking as described in claim 1, characterized in that, The placement platform (3) is square and is equipped with protective corners (32), which are made of neoprene rubber.

10. A method for simulating the transverse and longitudinal rolling motion in a water discharge experiment, characterized in that, The self-leveling water discharge experimental device for simulating horizontal and vertical rolling, as described in any one of claims 1-9, specifically includes the following steps: S1. Fill the water tank (1) with experimental seawater; S2. Start the hydraulic telescopic rod (21) to drive the scissor arm (22) to move, lift the placement platform (3) to the predetermined height, and then lock the hydraulic telescopic rod (21). S3. Based on the parameters of the horizontal sensor, control the hydraulic telescopic rod (41) to adjust the placement platform (3) to the horizontal. S4. Start the frame lifting mechanism to drive the ring horizontal frame (42) to rise until the telescopic pin (31) is at the same height as the insertion hole (421), then close the frame lifting mechanism (43). S5. Control the assembly of a pair of telescopic pins (31) with the socket (421), and then control the hydraulic telescopic rod two (41) to drive the placement platform (3) to reciprocate around the pair of telescopic pins (31) assembled with the socket (421), thereby simulating the lateral or longitudinal sway of the placement platform (3).

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