Flexible three-degree-of-freedom platform with posture adjusting, impact resisting and vibration isolating functions

Abstract

The invention discloses a flexible three-degree-of-freedom platform with attitude adjustment, impact resistance and vibration isolation functions, and relates to the technical field of heavy-load precision assembly and attitude adjustment, the flexible three-degree-of-freedom platform comprises a fixed base, a movable platform and a plurality of branch chains connected between the fixed base and the movable platform, the branch chains are flexible branch chains, and each flexible branch chain comprises a composite flexible hinge, a plurality of flexible connecting rods and a plurality of flexible connecting rods, the two ends of the composite flexible hinge are connected with the fixed base and the movable platform respectively, and the composite flexible hinge comprises a metal core and a composite material jacket wrapping the metal core; the transmission rod is in transmission connection with the composite flexible hinge; the hydraulic buffers are integrated in the flexible branch chains and used for absorbing impact loads; the buffering assembly is installed on the fixed base and used for buffering the movable platform through the flexible branch chains; by arranging the composite flexible hinge, the strength of metal and the anti-fatigue characteristic of a composite material are combined, the fatigue problem of a metal hinge is avoided, the service life of the platform under the heavy-load working condition is prolonged, and the reliability of the platform under the heavy-load working condition is improved.

Description

Technical Field

[0001] This invention relates to the field of heavy-duty precision assembly and attitude adjustment technology, specifically to a flexible three-degree-of-freedom platform that combines attitude adjustment and shock and vibration isolation functions. Background Technology

[0002] A flexible three-degree-of-freedom platform is a motion platform capable of translation along the X, Y, and Z axes, widely used in aerospace, precision manufacturing, and medical devices. In existing technologies, flexible three-degree-of-freedom platforms based on parallel mechanisms are a common implementation. This platform typically includes a fixed base, a moving platform, three flexible branches, and a drive mechanism. Each flexible branch is connected to the base and the moving platform at both ends via flexible metal hinges. The drive mechanism uses a servo motor coupled with a ball screw drive, achieving the three-degree-of-freedom motion of the moving platform by controlling the extension and retraction of each branch. To achieve precise control, the platform is also equipped with an optical grating displacement sensor for closed-loop feedback.

[0003] However, this existing technology has significant drawbacks in actual heavy-duty precision assembly scenarios: under long-term heavy-duty conditions, metal flexible hinges are prone to stress concentration and metal fatigue, which leads to a decrease in hinge deformation capacity and a shortened service life, affecting the reliability and stability of the platform. Especially in the heavy-duty assembly process of aircraft engine casings, large pressure vessels, etc., the platform needs to frequently withstand 1 to 5 tons of load and instantaneous impact, and the fatigue problem of metal hinges is particularly prominent, making it difficult to meet the requirements of continuous operation. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible three-degree-of-freedom platform that combines attitude adjustment and shock absorption and vibration isolation functions, in order to solve the problems of low reliability and service life of the core flexible components of the existing flexible three-degree-of-freedom platform under heavy load and impact conditions, and the lack of effective integrated shock resistance means for the overall platform.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions, comprising a fixed base, a moving platform, and multiple branches connecting the fixed base and the moving platform.

[0006] The branch is a flexible branch, and the flexible branch includes:

[0007] A composite flexible hinge, with its two ends connected to the fixed base and the moving platform respectively, the composite flexible hinge comprising a metal core and a composite material outer sleeve covering the metal core;

[0008] The transmission rod is connected to the composite flexible hinge transmission;

[0009] A hydraulic damper, integrated into the flexible branch, is used to absorb impact loads;

[0010] A buffer assembly, mounted on the fixed base, is used to buffer the moving platform via the flexible branch;

[0011] A degree-of-freedom adjustment device is installed between two adjacent flexible branches for adjusting the moving platform.

[0012] Furthermore, the composite material jacket is a carbon fiber reinforced composite material jacket, the metal core is an alloy structural steel core, the metal core and the composite material jacket are interference fit, and the two ends of the metal core form a flexible universal joint structure, enabling the composite flexible hinge to rotate at multiple angles.

[0013] Furthermore, the transmission rod is a multi-stage transmission rod, including two optical shafts connected by a spline to achieve axial extension and circumferential torque transmission. The hydraulic damper is a single-rod double-acting hydraulic cylinder. The hydraulic damper has a built-in accumulator and a throttle valve. When the impact load exceeds a preset threshold, the throttle valve operates to generate damping force.

[0014] Furthermore, the buffer assembly includes a mounting block, a slide rail, a sliding block, a guide rod, and a buffer spring. The mounting blocks are symmetrically mounted in pairs at the bottom of the fixed base. The slide rail is mounted on the top of the fixed base and located between the two mounting blocks. The sliding blocks are symmetrically slidably mounted on the slide rail.

[0015] Furthermore, the guide rod is symmetrically installed between the two mounting blocks and above the slide rail. The sliding block is slidably installed on the guide rod. The bottom of the flexible branch is movably hinged to the top of the sliding block. The two flexible branches are inclined outward. The buffer spring is sleeved on the guide rod. Each guide rod is sleeved with three buffer springs, two of which are located on the outer sides of the two sliding blocks respectively, and the other is located between the two sliding blocks.

[0016] Furthermore, the degree-of-freedom adjustment device includes a ball joint bearing, a connecting rod, a positioning block, a bearing block, a displacement block, and a drive assembly. The ball joint bearing is installed at both ends of the connecting rod. One end of the ball joint bearing of the connecting rod is rotatably installed at the bottom of the moving platform, and the other end of the ball joint bearing of the connecting rod is installed at the top of the positioning block.

[0017] Furthermore, the top of the support block is provided with a support groove, and the support groove is provided with symmetrically spaced mating plates. The bottom of the positioning block is provided with a slot that mates with the mating plates. The mating plates are provided with symmetrical positioning grooves. The outside of the support block is provided with a positioning rod, and the positioning rod is provided with a return spring. The positioning rod passes through the side wall of the support block through the return spring and is inserted into the positioning groove.

[0018] Furthermore, the drive assembly includes a servo motor and a planetary ball screw connected to the output end of the servo motor. The two ends of the planetary ball screw are supported by placement plates. The bottom of the placement plates is fixed to the top of the fixed base. The displacement block is slidably mounted on the planetary ball screw by ball nuts. The top of the displacement block is fixedly connected to the bottom of the support block. A limiting rod is provided between the two placement plates and above the planetary ball screw, and the support block is slidably mounted on the limiting rod.

[0019] Furthermore, the bottom of the moving platform is provided with axially distributed leveling feet, the middle of the moving platform is provided with a three-dimensional force sensor for real-time detection of contact force, the edge of the moving platform is provided with circumferentially distributed polyurethane buffer blocks, and the edge of the moving platform is provided with a T-slot for fixing the engine casing.

[0020] Furthermore, it also includes a control unit, which is electrically connected to the buffer assembly, the three-dimensional force sensor, and the grating ruler for detecting the displacement of the transmission rod. The control unit is configured to perform coordinated control of the translational motion of the moving platform in the X, Y, and Z directions based on the feedback signals from the three-dimensional force sensor and the grating ruler using a fuzzy PID control algorithm.

[0021] Compared with existing technologies, the flexible three-degree-of-freedom platform provided by this invention combines attitude adjustment and impact isolation functions. This invention uses a composite flexible hinge composed of a metal core and a composite material jacket as the core connecting component, which ingeniously integrates the high load-bearing capacity of metal materials with the high fatigue resistance and damping characteristics of composite materials. Structurally, it reduces the persistent problem of stress concentration and easy fatigue of traditional pure metal flexible hinges under heavy loads and impacts, thereby improving the reliability and service life of the platform.

[0022] Meanwhile, the moving platform integrates hydraulic dampers, independent buffer components, and degree-of-freedom adjustment devices into a flexible support chain system. This enables the platform to not only have precise three-degree-of-freedom attitude adjustment capabilities, but also to achieve the integration of passive vibration isolation and active impact resistance. When the platform is subjected to instantaneous impact loads, the hydraulic dampers and buffer components can work together to efficiently dissipate impact energy and suppress the vibration and overshoot of the moving platform. Thus, under harsh working conditions such as heavy-duty precision assembly (such as the docking of aero-engine casings), it provides stable position and attitude references and reliable impact protection for the supported equipment, and the overall performance is fundamentally enhanced. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1 A schematic diagram of the overall structure of the flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption and vibration isolation functions provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the fixed base and multiple flexible branches provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of the buffer assembly and flexible branch chain provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the degree-of-freedom adjustment device provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the structure of components such as the bearing block and the limiting rod provided in an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the positioning block and ball bearing components provided in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Fixed base; 2. Moving platform; 3. Flexible support chain; 301. Composite flexible hinge; 302. Transmission rod; 303. Hydraulic buffer; 4. Mounting block; 5. Slide rail; 6. Sliding block; 7. Guide rod; 8. Buffer spring; 9. Ball joint bearing; 10. Connecting rod; 11. Positioning block; 12. Bearing block; 13. Displacement block; 14. Bearing groove; 15. Mating plate; 16. Slot; 17. Positioning groove; 18. Positioning rod; 19. Return spring; 20. Servo motor; 21. Planetary ball screw; 22. Placement plate; 23. Limiting rod; 24. Leveling support; 25. Three-dimensional force sensor; 26. Polyurethane buffer block; 27. T-slot. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] As attached Figure 1 To be continued Figure 3 As shown:

[0034] Example 1:

[0035] This invention provides a flexible three-degree-of-freedom platform that combines attitude adjustment and shock absorption / vibration isolation functions, including a fixed base 1, a moving platform 2, and multiple branches connecting the fixed base 1 and the moving platform 2.

[0036] The branch is a flexible branch 3, and the flexible branch 3 includes:

[0037] The composite flexible hinge 301 has its two ends connected to the fixed base 1 and the moving platform 2 respectively. The composite flexible hinge 301 includes a metal core and a composite material outer sleeve covering the metal core.

[0038] The transmission rod 302 is connected to the composite flexible hinge 301 in a transmission manner;

[0039] The hydraulic buffer 303 is integrated into the flexible branch 3 and is used to absorb impact loads;

[0040] A buffer assembly, installed on the fixed base 1, is used to buffer the moving platform 2 via the flexible branch 3;

[0041] A degree-of-freedom adjustment device is installed between two adjacent flexible branches 3 for adjusting the moving platform 2.

[0042] It should be noted that the present invention uses a composite flexible hinge 301, which is composed of a metal core and a composite material jacket, as the core connecting component. This ingeniously combines the high load-bearing capacity of metal materials with the high fatigue resistance and damping characteristics of composite materials. Structurally, this reduces the persistent problem of stress concentration and easy fatigue of traditional pure metal flexible hinges under heavy loads and impacts, thereby improving the reliability and service life of the platform.

[0043] Meanwhile, this invention integrates the hydraulic buffer 303, the independent buffer assembly, and the degree-of-freedom adjustment device into the flexible branch chain 3 system, enabling the platform to not only have precise three-degree-of-freedom attitude adjustment capabilities, but also to achieve the integration of passive vibration isolation and active impact resistance. When the platform is subjected to instantaneous impact loads, the hydraulic buffer 303 and the buffer assembly can work together to efficiently dissipate impact energy and suppress the vibration and overshoot of the moving platform 2. Thus, under harsh working conditions such as heavy-load precision assembly (such as the docking of aero-engine casings), it provides a stable position and attitude reference and reliable impact protection for the supported equipment, and the overall performance is fundamentally enhanced.

[0044] Additional notes: Fixed base 1: Made of Q345 high-strength steel, welded into a regular hexagonal frame structure (side length 1200mm, height 300mm). Six branch connectors are evenly distributed on the top of the frame (spacing 600mm). Each connector has a built-in high-precision positioning pin hole (tolerance H7) for positioning and connecting with the fixed end of the flexible branch 3. Six leveling feet 24 are set at the bottom of the base (adjustment range ±50mm) to ensure that the platform levelness error is ≤0.05mm / m.

[0045] Moving platform 2: It is made of 7075 aluminum alloy and is integrally milled (dimensions 800mm×800mm×100mm). The upper surface is provided with T-slots 27 (for tooling fixtures). The lower surface is provided with 6 branch movable end connecting seats (with built-in spherical bearings) corresponding to the position of the fixed base 1 connecting seat. A three-dimensional force sensor 25 (range 0-10 tons, accuracy 0.1%FS) is embedded in the center of the moving platform 2 to detect the contact force during the docking process in real time.

[0046] Flexible branch 3 module: This is the core innovative component. Each branch includes a structure of "composite flexible hinge 301 + multi-stage transmission rod 302 + hydraulic buffer 303", and the specific design is as follows:

[0047] Composite Flexible Hinge 301: It adopts a double-layer structure of "carbon fiber reinforced composite material (T800) outer jacket + 40CrNiMoA metal core". The outer jacket is drum-shaped (200mm in length and 80mm in maximum diameter), and the inner wall is interference-fitted with the metal core (0.02mm interference). The two ends of the metal core are processed into flexible universal joint structures, which can achieve multi-angle rotation of ±12°. The composite material outer jacket is improved with fiber winding process (winding angle ±45°) to enhance torsional strength, so that the rated load of a single branch can reach 1.2 tons.

[0048] Multi-stage transmission rod 302: It consists of two sections of 45# steel heat-treated optical shafts (50mm in diameter and 300mm in length). The two sections of optical shafts are connected by a spline (spline accuracy grade 6) to realize axial extension and circumferential torque transmission. The outer side of the transmission rod 302 is fitted with a polytetrafluoroethylene guide sleeve (friction coefficient ≤0.01) to reduce motion friction loss.

[0049] Hydraulic buffer 303: Integrated into the transmission rod 302 near the moving platform 2, it adopts a single-rod double-acting structure (cylinder diameter 40mm, stroke 50mm), with a built-in accumulator (volume 50mL) and throttle valve. When the impact load is detected to exceed 1.5 times the rated load, the throttle valve automatically opens and absorbs the impact energy through hydraulic oil damping (buffering time 0.05~0.1s), with a maximum energy absorption of 500J.

[0050] Drive control module: It adopts a drive method of "20 servo motors + 21 planetary ball screws", and the specific configuration is as follows:

[0051] Drive unit: Panasonic A6 series servo motor 20 (power 5.5kW, rated torque 35N・m) is selected, and German Rexroth planetary ball screw 21 (lead 10mm, accuracy C3 grade, transmission clearance ≤0.005mm) is used. The screw nut is connected to the fixed end of the flexible support chain 3 for transmission. The single-axis drive speed can reach 500mm / s, and the positioning accuracy is ±0.02mm.

[0052] Control Unit: The Siemens S7-1500 PLC is used as the main controller, in conjunction with a 6-axis motion control card (sampling frequency 1kHz). It connects to the three-dimensional force sensor 25 of the moving platform 2, the grating rulers of each axis (resolution 0.1μm), and the pressure sensor signal of the hydraulic buffer 303. Through a control algorithm based on fuzzy PID, it realizes the coordinated control of three-degree-of-freedom motion. It is equipped with a 10-inch touch screen, which supports motion parameter setting (such as translation distance, rotation angle, buffer threshold) and real-time status monitoring.

[0053] Impact buffer module: In addition to the hydraulic buffer 303 built into the flexible branch 3, four polyurethane buffer blocks 26 (Shore D60 hardness, 50mm thickness) are set on the edge of the upper surface of the moving platform 2. When the docking workpiece collides with the moving platform 2 by accident, the buffer blocks can absorb 20% of the impact energy. With the real-time feedback of the three-dimensional force sensor 25 (response time ≤1ms), the dual protection of "passive buffering + active shutdown" is achieved.

[0054] In this embodiment: the composite material jacket is a carbon fiber reinforced composite material jacket, the metal core is an alloy structural steel core, the metal core and the composite material jacket are interference fit, and the two ends of the metal core form a flexible universal joint structure, so that the composite flexible hinge 301 can rotate at multiple angles.

[0055] It should be noted that the pre-stress generated by the interference fit in this composite structure effectively improves the load transfer path between the metal core and the composite material outer jacket, reducing the stress peak at the interface. The inherent high specific strength, high specific modulus, and excellent fatigue resistance of carbon fiber composites, combined with the high rigidity of the alloy steel core, ensures that the hinge maintains sufficient structural stiffness under large bending moments and alternating loads, while also absorbing energy through the elastic deformation of the composite material layers, significantly delaying the initiation and propagation of fatigue cracks. The flexible universal joint structure formed at both ends of the metal core provides the necessary rotational freedom for this platform, forming the basis for multi-angle attitude adjustment.

[0056] In this embodiment: the transmission rod 302 is a multi-stage transmission rod 302, including two optical shafts connected by splines to realize axial extension and circumferential torque transmission; the hydraulic buffer 303 is a single-rod double-acting hydraulic cylinder; the hydraulic buffer 303 has a built-in accumulator and a throttle valve; when the impact load exceeds a preset threshold, the throttle valve works to generate damping force.

[0057] It should be noted that the design of the multi-stage transmission rod 302 not only meets the platform's large-stroke attitude adjustment requirements, but its spline connection ensures the continuity and accuracy of torque transmission during axial extension and retraction, preventing transmission slippage. The hydraulic buffer 303 integrated into the branch chain constitutes the core active shock-resistant unit. The single-rod double-acting hydraulic cylinder allows for damping force in both compression and rebound strokes. The built-in accumulator stores some hydraulic oil and utilizes the compressibility of the internal gas to buffer peak pressure, providing initial buffering. When the system detects a severe impact load (such as equipment docking collision) exceeding the preset safety threshold, the control system commands the throttle valve to open or increase its opening, causing the hydraulic oil to generate a strong damping force as it flows through the throttle orifice, thereby rapidly dissipating the impact kinetic energy and converting the severe impact into smooth deceleration motion, effectively protecting the precision equipment on the moving platform 2.

[0058] In this embodiment: the buffer assembly includes mounting block 4, slide rail 5, sliding block 6, guide rod 7 and buffer spring 8. The mounting blocks 4 are symmetrically installed in pairs at the bottom of the fixed base 1. The slide rail 5 is installed on the top of the fixed base 1 and located between the two mounting blocks 4. The sliding block 6 is symmetrically slidably installed on the slide rail 5.

[0059] It should be noted that this buffer assembly constitutes the platform's basic passive vibration isolation system. Mounting block 4 and slide rail 5 provide a stable mounting base for the entire assembly. Sliding block 6 can slide with low friction on slide rail 5, transferring the force from flexible support chain 3 to buffer spring 8. This symmetrical arrangement ensures balanced force distribution, avoiding jamming or additional wear caused by uneven loading, and providing stable and smooth mechanical guidance for subsequent buffering actions.

[0060] In this embodiment: the guide rod 7 is symmetrically installed between the two mounting blocks 4 and above the slide rail 5. The sliding block 6 is slidably installed on the guide rod 7. The bottom of the flexible branch 3 is movably hinged to the top of the sliding block 6. The two flexible branches 3 are inclined outward. The buffer spring 8 is sleeved on the guide rod 7. Each guide rod 7 is sleeved with three buffer springs 8, two of which are located on the outer sides of the two sliding blocks 6 respectively, and the other is located between the two sliding blocks 6.

[0061] It should be noted that: the guide rod 7 provides precise linear motion constraints for the sliding block 6, ensuring that its motion trajectory is consistent with the force direction of the platform. The hinged connection between the bottom of the flexible branch 3 and the sliding block 6, combined with the inclined arrangement of the branch, decomposes the complex spatial motion of the moving platform 2 into the linear motion of the sliding block 6 along the guide rod 7. The specific layout of the three buffer springs 8 forms an efficient buffering mechanism: the spring located on the outside of the two sliding blocks 6 mainly resists the tension that causes the branch to open, while the spring located between the two sliding blocks 6 mainly resists the pressure that causes the branch to close. This design allows the buffer assembly to absorb energy through the compression deformation of the corresponding springs, providing continuous and smooth buffering force, and significantly attenuating the vibration transmitted to the fixed base 1, regardless of whether the platform is subjected to tensile or compressive impact.

[0062] As attached Figure 1 Appendix Figure 4 To be continued Figure 6 As shown:

[0063] Example 2:

[0064] In this embodiment: the degree of freedom adjustment device includes a ball joint bearing 9, a connecting rod 10, a positioning block 11, a bearing block 12, a displacement block 13 and a drive assembly. The ball joint bearing 9 is installed at both ends of the connecting rod 10. One end of the ball joint bearing 9 of the connecting rod 10 is rotatably installed at the bottom of the moving platform 2, and the other end of the ball joint bearing 9 of the connecting rod 10 is installed at the top of the positioning block 11.

[0065] It should be noted that the degree-of-freedom adjustment device is the key actuator for achieving precise three-degree-of-freedom motion of the moving platform 2. The application of the ball joint bearing 9 ensures that the connecting rod 10 can adapt to the multi-directional angular displacements generated by the moving platform 2 during attitude adjustment while transmitting the driving force, avoiding motion interference and additional stress. The connecting rod 10 transmits the linear motion of the drive component to the positioning block 11, which then pushes or pulls the moving platform 2 through the ball joint, achieving precise changes in its spatial posture. This structure provides the platform with a stable and reliable force and motion input point.

[0066] In this embodiment: the top of the support block 12 is provided with a support groove 14, and the support groove 14 is provided with symmetrically spaced mating plates 15. The bottom of the positioning block 11 is provided with a slot 16 that mates with the mating plates 15. The mating plates 15 are provided with symmetrically arranged positioning grooves 17. The outside of the support block 12 is provided with a positioning rod 18. The positioning rod 18 is provided with a return spring 19. The positioning rod 18 passes through the side wall of the support block 12 through the return spring 19 and is inserted into the positioning groove 17.

[0067] It should be noted that this connecting mechanism enables a quick and reliable connection and positioning between the positioning block 11 and the bearing block 12. The mating design of the plate 15 and the slot 16 ensures precise circumferential and radial positioning during engagement, effectively resisting torsional torque and lateral forces during operation. The positioning rod 18 automatically springs into the positioning groove 17 under the action of the return spring 19, achieving mechanical self-locking of the connection and ensuring its robustness, preventing loosening under vibration and impact. This design facilitates assembly and maintenance while ensuring the rigidity of power transmission.

[0068] In this embodiment: the drive assembly includes a servo motor 20 and a planetary ball screw 21 connected to the output end of the servo motor 20. The two ends of the planetary ball screw 21 are supported by a placement plate 22. The bottom of the placement plate 22 is fixed to the top of the fixed base 1. The displacement block 13 is slidably mounted on the planetary ball screw 21 by a ball nut. The top of the displacement block 13 is fixedly connected to the bottom of the bearing block 12. A limiting rod 23 is provided between the two placement plates 22 and above the planetary ball screw 21, and the bearing block 12 is slidably mounted on the limiting rod 23.

[0069] It should be noted that the drive assembly provides high-precision, high-rigidity linear displacement output. The servo motor 20 ensures precise control and rapid response. Compared to ordinary ball screws, the planetary ball screw 21 has higher load-bearing capacity, rigidity, and longer service life, making it particularly suitable for the heavy-duty conditions of this invention. The displacement block 13 converts the rotational motion of the screw into linear motion, driving the bearing block 12 and the entire degree-of-freedom adjustment unit connected to it to move. The sliding engagement between the limit rod 23 and the bearing block 12 constitutes an effective anti-rotation mechanism, ensuring that the bearing block 12 and the structure above it only perform precise linear motion along the screw axis, eliminating unnecessary torsion, thereby ensuring the accuracy of the pose adjustment and repeatability of the moving platform 2.

[0070] In this embodiment: the bottom of the moving platform 2 is provided with axially distributed leveling feet 24, the middle of the moving platform 2 is provided with a three-dimensional force sensor 25 for real-time detection of contact force, the edge of the moving platform 2 is provided with circumferentially distributed polyurethane buffer blocks 26, and the edge of the moving platform 2 is provided with a T-slot 27 for fixing the engine casing.

[0071] It should be noted that: the leveling feet 24 are used for rough leveling and auxiliary support of the moving platform 2 during initial installation or in non-working states, increasing system stability. The three-dimensional force sensor 25 is the core sensing element in the precision assembly process, capable of real-time monitoring of the contact force and torque between the moving platform 2 and the workpiece to be assembled, providing closed-loop feedback signals to the control unit, achieving smooth and precise force-controlled assembly. The circumferentially distributed polyurethane buffer blocks 26 serve as the last physical line of defense. Under extreme overload conditions, they absorb the remaining impact energy through their high elastic deformation, preventing rigid collisions between the moving platform 2 and the fixed base 1 or other structures, thus protecting the platform structure. The T-slot 27 provides a universal and flexible clamping interface, facilitating quick and secure clamping of various manipulated objects such as aircraft engine casings.

[0072] In this embodiment, a control unit is also included. The control unit is electrically connected to the buffer assembly, the three-dimensional force sensor 25, and the grating ruler for detecting the displacement of the transmission rod 302. The control unit is configured to perform coordinated control of the three-degree-of-freedom motion of the moving platform 2 based on the feedback signals from the three-dimensional force sensor 25 and the grating ruler using a fuzzy PID control algorithm.

[0073] It should be noted that the control unit is the "brain" of the entire platform, realizing intelligent coordination between posture adjustment and shock absorption / vibration isolation functions. The grating ruler provides precise displacement feedback for each branch, forming a position closed loop. The three-dimensional force sensor 25 provides real-time force / torque feedback, forming a force closed loop. The fuzzy PID control algorithm combines the robustness of fuzzy logic with the precision of PID control, effectively handling the nonlinearity, time-varying nature, and uncertainties present in heavy-duty precision assembly. The control unit comprehensively processes position and force information, generating real-time control commands for the servo motors 20 in each degree-of-freedom adjustment device. This not only enables high-precision trajectory and attitude tracking of the moving platform 2, but also allows for rapid adjustment of the motion state of each branch when abnormal contact force or impact is detected. It coordinates with the hydraulic buffer 303 and buffer components to actively suppress vibration and impact, achieving intelligent control that combines rigidity and flexibility, ultimately ensuring the smoothness, precision, and safety of the entire assembly process.

[0074] Additionally, the specific implementation process of the fuzzy PID control algorithm includes: First, the force / torque error detected by the three-dimensional force sensor 25 and the position error detected by each grating ruler are used as input variables of the controller; second, the input variables are fuzzified, and the fuzzy subset used in the fuzzification process includes {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, and its membership function adopts a trigonometric function; then, the fuzzified variables are inferred according to a preset fuzzy rule library, which contains 49 rules such as "if the position error is negative large and the force error is positive large, then the output torque is positive large", covering various typical working conditions; finally, the inference results are defuzzified, and the correction amount of the real-time PID proportional, integral, and derivative parameters is calculated using the centroid method, thereby realizing the online adaptive adjustment of the control parameters of the servo motor 20, and finally completing the precise, compliant, and coordinated control of the three-degree-of-freedom motion of the moving platform 2.

[0075] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions, including: A fixed base (1), a moving platform (2), and a plurality of branches connecting the fixed base (1) and the moving platform (2), characterized in that, The branch is a flexible branch (3), and the flexible branch (3) includes: A composite flexible hinge (301) is connected at both ends to the fixed base (1) and the moving platform (2) respectively. The composite flexible hinge (301) includes a metal core and a composite material jacket covering the metal core. The transmission rod (302) is connected to the composite flexible hinge (301) in a transmission manner; A hydraulic buffer (303), integrated in the flexible branch (3), is used to absorb impact loads; A buffer assembly, mounted on the fixed base (1), is used to buffer the moving platform (2) via the flexible branch (3); A degree-of-freedom adjustment device is installed between two adjacent flexible branches (3) for adjusting the moving platform (2).

2. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions as described in claim 1, characterized in that, The composite material jacket is a carbon fiber reinforced composite material jacket, the metal core is an alloy structure steel core, the metal core and the composite material jacket are interference fit, and the two ends of the metal core form a flexible universal joint structure, so that the composite flexible hinge (301) can rotate at multiple angles.

3. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions as described in claim 2, characterized in that, The transmission rod (302) is a multi-stage transmission rod (302), including two optical shafts connected by splines to realize axial extension and circumferential torque transmission. The hydraulic damper (303) is a single-rod double-acting hydraulic cylinder. The hydraulic damper (303) has a built-in accumulator and a throttle valve. When the impact load exceeds the preset threshold, the throttle valve works to generate damping force.

4. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions as described in claim 1, characterized in that, The buffer assembly includes a mounting block (4), a slide rail (5), a sliding block (6), a guide rod (7), and a buffer spring (8). The mounting blocks (4) are symmetrically mounted in pairs at the bottom of the fixed base (1). The slide rail (5) is mounted on the top of the fixed base (1) and located between the two mounting blocks (4). The sliding blocks (6) are symmetrically slidably mounted on the slide rail (5).

5. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions as described in claim 4, characterized in that, The guide rod (7) is symmetrically installed between the two mounting blocks (4) and above the slide rail (5). The sliding block (6) is slidably installed on the guide rod (7). The bottom of the flexible branch (3) is movably hinged to the top of the sliding block (6). The two flexible branches (3) are inclined outward. The buffer spring (8) is sleeved on the guide rod (7). Each guide rod (7) is sleeved with three buffer springs (8), two of which are located on the opposite outer sides of the two sliding blocks (6), and the other is located between the two sliding blocks (6).

6. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption and vibration isolation functions as described in claim 1, characterized in that, The degree-of-freedom adjustment device includes a ball joint bearing (9), a connecting rod (10), a positioning block (11), a bearing block (12), a displacement block (13), and a drive assembly. The ball joint bearing (9) is installed at both ends of the connecting rod (10). At one end, the ball joint bearing (9) of the connecting rod (10) is rotatably installed at the bottom of the moving platform (2), and at the other end, the ball joint bearing (9) of the connecting rod (10) is installed at the top of the positioning block (11).

7. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions as described in claim 6, characterized in that, The top of the support block (12) is provided with a support groove (14), and the support groove (14) is provided with symmetrically spaced mating plates (15). The bottom of the positioning block (11) is provided with a slot (16) that mates with the mating plates (15). The mating plates (15) are provided with symmetrically arranged positioning grooves (17). The outside of the support block (12) is provided with a positioning rod (18), and the positioning rod (18) is provided with a return spring (19). The positioning rod (18) passes through the side wall of the support block (12) through the return spring (19) and is inserted into the positioning groove (17).

8. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption and vibration isolation functions as described in claim 7, characterized in that, The drive assembly includes a servo motor (20) and a planetary ball screw (21) connected to the output end of the servo motor (20). The two ends of the planetary ball screw (21) are supported by a placement plate (22). The bottom of the placement plate (22) is fixed to the top of the fixed base (1). The displacement block (13) is slidably mounted on the planetary ball screw (21) by a ball nut. The top of the displacement block (13) is fixedly connected to the bottom of the support block (12). A limit rod (23) is provided between the two placement plates (22) and above the planetary ball screw (21) parallel to it. The support block (12) is slidably mounted on the limit rod (23).

9. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions as described in claim 1, characterized in that, The bottom of the moving platform (2) is provided with axially distributed leveling feet (24), the middle part of the moving platform (2) is provided with a three-dimensional force sensor (25) for real-time detection of contact force, the edge of the moving platform (2) is provided with circumferentially distributed polyurethane buffer blocks (26), and the edge of the moving platform (2) is provided with a T-slot (27) for fixing the engine casing.

10. The flexible three-degree-of-freedom platform with both attitude adjustment and shock absorption / vibration isolation functions according to any one of claims 1 to 9, characterized in that, It also includes a control unit, which is electrically connected to the buffer assembly, the three-dimensional force sensor (25) and the grating ruler for detecting the displacement of the transmission rod (302). The control unit is configured to perform coordinated control of the three-degree-of-freedom motion of the moving platform (2) based on a fuzzy PID control algorithm and according to the feedback signals of the three-dimensional force sensor (25) and the grating ruler.

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