Flexible manipulator with gripping force self-adaptive capability and operation method thereof

Abstract

The invention relates to a flexible manipulator with gripping force adaptive capability and an operation method thereof, the flexible manipulator comprises a flexible finger, a transmission mechanism and a driving mechanism, the driving mechanism adopts a first screw rod and a second screw rod which are connected in series and is provided with a fixed-torque pre-tightening device, the driving mechanism limits the rotation of the first screw rod and the second screw rod in low load, and the driving mechanism drives the first screw rod and the second screw rod to rotate. The manipulator is quickly closed at a first large lead; and when the load is high, the first screw rod and the second screw rod overcome the pre-tightening torque to rotate, so that the flexible manipulator can perform low-speed and high-force grasping at a second small lead. According to the mechanical arm, the problem that an existing mechanical arm is difficult to give consideration to fast movement and large force output can be solved, automatic and passive switching of force-speed characteristics is achieved through a pure mechanical structure, the structure is compact, control is easy, reliability is high, and the adaptability of the mechanical arm to different grabbing tasks is remarkably improved.

Description

Technical Field

[0001] This invention relates to a flexible robotic hand with adaptive gripping force and its operation method, belonging to the field of robotic hand technology. Background Technology

[0002] In fields such as industrial automation, special-purpose robots, and service robots, robotic arms, as end effectors, are crucial for their grasping and manipulation capabilities. An ideal robotic arm should be able to adapt to objects of different sizes, shapes, and rigidities, and exhibit different performance characteristics at different stages of a task. For example, when rapidly approaching a target object, the robotic arm needs to close quickly to improve operational efficiency; while when stably grasping an object or applying manipulation forces, the robotic arm needs to provide sufficiently large and stable gripping force to ensure operational reliability.

[0003] Existing robotic arm designs often struggle to balance the conflicting demands of rapid movement and high-power output. Robotic arms driven by fixed gear ratios suffer from slow opening and closing speeds and reduced efficiency if a large reduction ratio is chosen to achieve high gripping force; conversely, a small reduction ratio chosen to increase speed results in insufficient output force. To address this issue, some designs employ complex electromechanical systems, such as adding extra motors, clutches, and gearboxes to switch between different gear ratios. However, this undoubtedly increases the size, weight, cost, and control system complexity of the robotic arm, reducing system reliability.

[0004] Furthermore, for flexible robotic hands, the fingers typically possess a certain degree of flexibility to adapt to irregular objects, such as biomimetic fish fin structures. However, their drive mechanisms are mostly still traditional rigid transmissions, failing to fundamentally solve the problem of adaptive adjustment of force and speed characteristics. Summary of the Invention

[0005] This invention provides a flexible robotic arm with adaptive gripping force and its operating method, aiming to solve at least one of the technical problems existing in the prior art. To this end, the flexible robotic arm with adaptive gripping force and its operating method proposed in this invention have a compact structure and simple control, and can automatically and passively adjust their output characteristics according to the actual gripping load.

[0006] The technical solution of this invention relates, in one aspect, to a flexible robotic arm, comprising: The robotic arm transmission mechanism comprises a flexible finger for grasping an object, a robotic arm transmission mechanism for driving the flexible finger to open and close to grasp the object, and a drive mechanism for providing a first lead and a second lead for grasping linear driving force and allowing adaptive variable transmission ratio, wherein the robotic arm transmission mechanism is connected to the flexible finger and the drive mechanism respectively. The drive mechanism includes a drive housing, a first lead screw, a second lead screw, a first nut, a second nut, and a constant torque preload device. The first lead screw and the second lead screw are fixedly connected, the first lead screw and the first nut are threadedly connected, the first nut is fixedly connected to an input flange, the input flange is fixedly connected to the output shaft of the driver, the second lead screw and the second nut are threadedly connected, and the second nut is fixedly connected to the robot arm transmission mechanism. The constant torque preload device is slidably connected to the drive housing to allow linear movement of the constant torque preload device while restricting its rotation. The constant torque preload device provides a preset constant preload torque for limiting the rotation of the first lead screw. The first nut is rotatably connected to the drive box to allow the first nut to rotate and limit its linear motion, thereby allowing the generation of a gripping driving force of the flexible finger based on the first lead. The second nut is slidably connected to the drive housing to allow linear movement of the second nut while restricting its rotation, thereby allowing the generation of a gripping driving force for the flexible finger based on the second lead.

[0007] Furthermore, the constant torque preload device includes a constant torque damping turntable, which is connected to the first lead screw via a shaft end fixing flange.

[0008] Furthermore, the drive mechanism also includes a first guide rail and a first slider that match the first lead, and a second guide rail and a second slider that match the second lead. The first guide rail and the second guide rail are fixedly disposed on the inner side wall of the drive box. The first slider is movably disposed on the first guide rail, and the second slider is movably disposed on the second guide rail. The first slider is fixedly connected to the second nut, and the second slider is fixedly connected to the constant torque preload device.

[0009] Furthermore, the drive mechanism also includes a nut connecting block and a pre-tightening device connecting block. The nut connecting block is fixedly connected to the second slider and the second nut, respectively. The pre-tightening device connecting block is fixedly connected to the second slider and the constant torque pre-tightening device, respectively.

[0010] Furthermore, the robotic arm transmission mechanism includes a finger base connecting rod, a slider, a rocker arm, and a frame. The finger base connecting rod is fixedly connected to the flexible finger. The inner side of the finger base connecting rod is rotatably connected to the slider. The outer side of the finger base connecting rod is rotatably connected to the upper side of the rocker arm. The lower side of the rocker arm is rotatably connected to the frame.

[0011] Furthermore, the robotic arm transmission mechanism also includes an optical axis and a rectangular connecting frame. The upper side of the optical axis is fixedly connected to the slider, and the two sides of the rectangular connecting frame are fixedly connected to the frame and the drive box, respectively.

[0012] Furthermore, the slider includes a connecting part and a limiting part, the connecting part is fixedly connected to the limiting part, the connecting part is rotatably connected to the finger base connecting rod, and the limiting part is fixedly connected to the optical axis; the frame is provided with a limiting rod that allows contact with the limiting part to restrict the closure of the flexible finger.

[0013] Furthermore, the drive mechanism also includes a bearing mounting base, a nut bearing, a nut retaining ring, and a nut limiting ring. The bearing mounting base is fixedly connected to the drive box. The nut bearing is disposed between the bearing mounting base and the first nut. The nut retaining ring and the nut limiting ring are respectively disposed on both sides of the nut bearing.

[0014] Furthermore, an output flange is fixedly connected to the end of the second lead screw away from the first lead screw, and the output flange is fixedly connected to the optical axis; an input flange is fixedly connected to the end of the first lead screw away from the second lead screw, and the input flange is fixedly connected to the output shaft of the driver.

[0015] Furthermore, the flexible finger includes a double-finger tip block and a single-finger tip block that allow partial crossing to form a closed grasping space.

[0016] Another aspect of the technical solution of the present invention relates to an operation method for a flexible robotic hand with adaptive gripping force, applied to the flexible robotic hand with adaptive gripping force in the above embodiments of the present invention. The method includes the following steps: When the reaction torque of the gripping load on the flexible manipulator is lower than a preset torque threshold, the first nut is rotated by the driver, and the first lead screw and the second lead screw move linearly with a first lead while the first lead screw is restricted from rotating by the fixed torque preload device. When the reaction torque of the gripping load on the flexible manipulator reaches or exceeds the preset torque threshold, the first nut is rotated and the first and second lead screws are rotated through thread engagement. In the state where the second nut is restricted from rotating, the second nut is made to move linearly with the second lead.

[0017] The beneficial effects of this invention are as follows.

[0018] This invention discloses a flexible robotic arm with adaptive gripping force and its operating method. The arm features a compact structure, reliable transmission, and the ability to automatically switch between a fast, low-force closing mode and a slow, high-force gripping mode based on the gripping force. Specifically, the drive mechanism automatically and passively switches between these modes based on the actual gripping load, achieving intrinsic mechanical intelligence and improving adaptability to different objects. This invention integrates two transmission ratios into a single series-connected lead screw system, switching via a torque preload device. Compared to solutions using multiple gear systems and clutches, this design is simpler, more compact, has fewer potential failure points, and is more reliable. Before contacting an object, the robotic arm can quickly close using a large lead mode, shortening the non-working stroke time and improving overall operational efficiency. When a larger gripping force is required, the system automatically switches to a small lead high-force mode, providing stable and reliable clamping force to prevent object slippage or operational failure. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the overall structure of the flexible robotic arm according to an embodiment of the present invention.

[0020] Figure 2 This is a cross-sectional view of the flexible manipulator according to an embodiment of the present invention.

[0021] Figure 3 for Figure 1 Enlarged diagram of point A.

[0022] Figure 4 This is a schematic diagram of the connection structure between the second lead screw and the second nut according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the connection structure of the constant torque preload device according to an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of the connection structure between the first lead screw and the first nut in an embodiment of the present invention.

[0025] Figure 7 This is a schematic diagram of the closed state of the flexible robotic arm according to an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the open state of the flexible robotic arm according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 100. Flexible fingers; 110. Finger blocks; 111. Double fingertip finger blocks; 112. Single fingertip finger blocks; 200. Robotic arm transmission mechanism; 210. Finger base connecting rod; 211. Base connecting plate; 212. Base protruding rod; 220. Slider; 221. Connecting part; 222. Limiting part; 230. Rocker arm; 240. Frame; 241. Intermediate connecting plate; 242. Protruding end; 243. Limiting rod; 250. Optical axis; 260. Rectangular connecting frame; 300. Drive mechanism; 310. First lead screw; 311. Input flange; 312. Bearing mounting base; 313. Nut bearing; 314. Nut retaining ring; 315. Nut limiting ring; 316. Coupling; 320. Second lead screw; 321. Output flange; 322. First guide rail; 323. First slider; 324. Nut connecting block; 330. First nut; 340. Second nut; 350. Constant torque preload device; 351. Constant torque damping turntable; 352. Shaft end fixing flange; 353. Second guide rail; 354. Second slider; 355. Preload device connecting block; 360. Drive box; 370. Driver; 371. Output shaft. Detailed Implementation

[0028] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0029] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," "right," "top," and "bottom" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0030] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and not for limiting the invention. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0031] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from one another. For example, without departing from the scope of this disclosure, a first element may also be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0032] See Figures 1 to 8 The flexible manipulator with adaptive gripping force of the present invention includes a flexible finger 100 for grasping an object and a manipulator transmission mechanism 200 for driving the flexible finger 100 to open and close to grasp the object, as well as a drive mechanism 300 for providing a gripping linear driving force with a first lead and a second lead and allowing adaptive variable transmission ratio. The manipulator transmission mechanism 200 is connected to the flexible finger 100 and the drive mechanism 300 respectively. The drive mechanism 300 includes a drive housing 360, a first lead screw 310, a second lead screw 320, a first nut 330, a second nut 340, and a constant torque preload device 350. The first lead screw 310 is fixedly connected to the second lead screw 320, and the first lead screw 310 is threadedly connected to the first nut 330. The first nut 330 is fixedly connected to the input end flange 311, which is fixedly connected to the output shaft 371 of the driver 370. The second lead screw 320 is threadedly connected to the second nut 340, and the second nut 340 is fixedly connected to the robot arm transmission mechanism 200. The constant torque preload device 350 is slidably connected to the drive housing 360 to allow linear movement of the constant torque preload device 350 while restricting its rotation. The constant torque preload device 350 provides a preset constant preload torque to limit the rotation of the first lead screw 310. The first nut 330 is rotatably connected to the drive housing 360 to allow the first nut 330 to rotate while limiting its linear motion, thereby allowing the generation of a gripping driving force for the flexible finger 100 based on the first lead. The second nut 340 is slidably connected to the drive housing 360 to allow the second nut 340 to move linearly while limiting its rotation, thereby allowing the generation of a gripping driving force for the flexible finger 100 based on the second lead.

[0033] See also Figure 1 and Figure 2 The flexible robotic hand of this invention includes a flexible finger 100, a robotic hand transmission mechanism 200, and a drive mechanism 300 that allows adaptive variable transmission ratio. The upper and lower sides of the robotic hand transmission mechanism 200 are respectively connected to the flexible finger 100 and the drive mechanism 300. A driver 370 is connected to the lower side of the drive mechanism 300, which drives the drive mechanism 300 to move so that the flexible finger 100 closes. It is understood that the driver 370 used in this invention to provide gripping for the flexible robotic hand can be a rotary motor or a servo motor, etc.

[0034] Specifically, the drive mechanism 300 includes a first lead screw 310, a first nut 330, a second lead screw 320, and a second nut 340. The first nut 330 is sleeved on the first lead screw 310, and the second nut 340 is sleeved on the second nut 340. The lower side of the second lead screw 320 is fixedly and interlocked with the upper side of the first lead screw 310 via a coupling 316. The upper side of the second lead screw 320 is threadedly connected to the second nut 340. The second nut 340 is fixedly connected to the lower side of the output flange 321, and the upper side of the output flange 321 is fixedly connected to the robot transmission mechanism 200. The lower side of the first lead screw 310 is threadedly connected to the first nut 330, and the first nut 330 is fixedly connected to the input flange 311. The input flange 311 is fixedly connected to the output shaft 371 of the driver 370. The first lead screw 310 is connected to a constant torque preload device 350. Furthermore, the first lead screw 310 and the second lead screw 320 are coaxially rigidly connected through a single diaphragm coupling 316, forming a functionally series "combined lead screw".

[0035] The operating method of the flexible robotic hand with adaptive gripping force according to the present invention includes at least the following steps: When the reaction torque of the gripping load on the flexible manipulator is lower than the preset torque threshold, the first nut 330 is rotated by the driver 370, and the first lead screw 310 is restricted from rotating by the fixed torque preload device 350, so that the first lead screw 310 and the second lead screw 320 perform rapid, low-force linear motion with the first lead. When the reaction torque of the gripping load on the flexible manipulator reaches or exceeds the preset torque threshold, the first nut 330 is rotated and the first lead screw 310 and the second lead screw 320 are rotated through thread engagement. In the state where the second nut 340 is restricted and does not rotate, the second nut 340 is made to perform slow and powerful linear motion with the second lead.

[0036] This invention provides gripping driving force through a first lead and a second lead, respectively, based on the size of the gripping load (i.e., the driving force required to grip the object) of the flexible finger 100, wherein the first lead is greater than the second lead. Specifically, the constant torque preload device 350 of this invention provides a preset constant preload torque to suppress the rotation of the first lead screw 310. When the axial load generated by the flexible manipulator during gripping generates a reaction torque on the first lead screw 310 that is less than the preload torque, the first lead screw 310 does not rotate, and the first nut 330 rotates but cannot move linearly. This drives the combined lead screw formed by the first lead screw 310 and the second lead screw 320 to generate a rapid, small-force linear movement based on the first lead, providing a rapid, small-force gripping driving force for the flexible finger 100. When the flexible robotic arm grasps, the reaction torque generated reaches or exceeds the preload torque, allowing the first lead screw 310 to overcome the constraint of the constant torque preload device 350 and rotate. The first lead screw 310 drives the second lead screw 320 to rotate. At the same time, since the second nut 340 can only move linearly and cannot rotate, it drives the second nut 340 to generate a slow and powerful linear motion based on the second lead, providing a slow and powerful gripping driving force for the flexible finger 100.

[0037] This invention relates to a flexible robotic hand with adaptive gripping force. Through a purely mechanical structure, it achieves automatic and passive switching of force-speed characteristics, offering advantages such as compact structure, fast response, high energy efficiency, and no need for complex switching control, significantly improving the robotic hand's adaptability to different gripping tasks. The drive mechanism 300 of this invention can automatically and passively switch between a fast, low-force mode and a slow, high-force mode based on the actual gripping load, achieving intrinsic intelligence at the mechanical level and improving adaptability to different objects. This invention integrates two transmission ratios into a series-connected lead screw system, achieving switching through a torque preload device. Compared to solutions using multiple gear systems and clutches, this design is simpler, more compact, has fewer potential failure points, and is more reliable. Before contacting an object, the robotic hand can utilize a large lead mode for rapid, low-force closure (first lead), shortening the non-working stroke time and thus improving overall operational efficiency. When a larger gripping force is required, the system automatically switches to a small lead, high-force mode (second lead), providing stable and reliable clamping force to prevent object slippage or operational failure.

[0038] In some embodiments of the present invention, the flexible finger 100 of the present invention adopts a biomimetic fish fin structure. Its rib structure enables it to generate an envelope surface when in contact with a target object, thus exhibiting good shape adaptability. Specifically, the flexible finger 100 of the present invention includes a double fingertip block 111 and a single fingertip block 112. When the flexible robotic hand is closed, the single fingertip block 112 can be inserted between the two tips of the double fingertip block 111, causing the double fingertip block 111 and the single fingertip block 112 to partially intersect, thereby forming a closed grasping space.

[0039] See also Figure 1 and Figure 3 The flexible finger 100 includes two fingertip blocks 110, each fingertip block 110 being conical in shape with its tip curved inward. The two fingertip blocks 110 can partially intersect to form a closed grasping space. Further, to enhance grasping ability, one fingertip block 110 is a double fingertip block 111, and the other fingertip block 110 is a single fingertip block 112. (See [reference]). Figure 7 and Figure 8 When the two fingertips 110 move in opposite directions, the flexible robotic hand opens its palm; when the two fingertips 110 move towards each other, the flexible robotic hand closes its palm, at which point it can grasp an object. (See also...) Figure 3 The two tips of the double fingertip block 111 are spaced apart. When the two fingertip blocks 110 move towards each other, the tip of the single fingertip block 112 can be inserted between the two tips of the double fingertip block 111. It can be understood that the flexible finger 100 is fixed to the robotic arm transmission mechanism 200 by finger screws.

[0040] In some embodiments of the present invention, the robotic arm transmission mechanism 200 is a planar rocker arm 230 and slider 220 mechanism. The robotic arm transmission mechanism 200 includes a finger base connecting rod 210, a slider 220, a rocker arm 230, and a frame 240. The finger base connecting rod 210 is fixedly connected to the flexible finger 100. The inner side of the finger base connecting rod 210 is rotatably connected to the slider 220, and the outer side of the finger base connecting rod 210 is rotatably connected to the upper side of the rocker arm 230. The lower side of the rocker arm 230 is rotatably connected to the frame 240. Further, the robotic arm transmission mechanism 200 also includes an optical axis 250 and a connecting frame. The upper side of the optical axis 250 is fixedly connected to the slider 220, and the optical axis 250 is fixedly connected to the second lead screw 320 through the output end flange 321 of the drive mechanism 300. The upper side of the connecting frame is fixedly connected to the frame 240, and the lower side of the connecting frame is fixedly connected to the drive box 360 of the drive mechanism 300. Furthermore, the slider 220 includes a connecting part 221 and a limiting part 222. The connecting part 221 is fixedly connected to the limiting part 222. The frame 240 is provided with a limiting rod 243 that allows contact with the limiting part 222 to limit the closure of the flexible finger 100.

[0041] Specifically, see Figure 3 and Figure 7 When the drive mechanism 300 moves the optical axis 250 downward, the optical axis 250 moves the slider 220 downward, causing the inner side of the finger base connecting rod 210 and the inner side of the flexible finger 100 to move downward, and also causing the upper end of the rocker arm 230 to rotate inward. Simultaneously, with the cooperation of the frame 240, the tips of the two finger blocks 110 of the flexible finger 100 move inward toward each other, allowing the flexible robotic hand to grasp objects. (See also...) Figure 3 and Figure 8 When the drive mechanism 300 drives the optical axis 250 to move upward, the optical axis 250 drives the slider 220 to move upward, causing the inner side of the finger base connecting rod 210 and the inner side of the flexible finger 100 to move upward, and causing the upper end of the rocker arm 230 to rotate outward. At the same time, with the cooperation of the frame 240, the tips of the two finger blocks 110 of the flexible finger 100 move outward and backward, and the flexible manipulator can release the object.

[0042] It should be noted that the top plate of the drive housing 360 of the drive mechanism 300 is provided with an output hole. The diameters of the output flange 321 and the optical shaft 250 are smaller than the diameter of the output hole, so that the output flange 321 and the optical shaft 250 are spaced apart from the drive housing 360, thereby allowing the output flange 321 and the optical shaft 250 to move through the output hole. Furthermore, the bottom plate of the drive housing 360 of the drive mechanism 300 is provided with an input hole. The diameters of the input flange 311 and the output shaft 371 of the driver 370 are smaller than the diameter of the input hole, so that the input flange 311 is spaced apart from the drive housing 360, thereby allowing the input flange 311 to rotatably pass through the input hole.

[0043] In some specific embodiments of the present invention, four finger base connecting rods 210 are provided, see [link]. Figure 3 Two finger blocks 110 are respectively disposed on the left and right sides of the flexible robotic hand. Two finger base connecting rods 210 are connected to the front and rear sides of the left-side finger block 110, respectively, and the other two finger base connecting rods 210 are connected to the front and rear sides of the right-side finger block 110, respectively. Specifically, the finger base connecting rod includes a base connecting plate 211 and two base protrusions 212. The upper side of the base connecting plate 211 is connected to the bottom surface of the flexible finger 100. The two base protrusions 212 are respectively disposed on the outer and inner sides of the lower end of the base connecting plate 211. The inner base protrusion 212 is rotatably connected to the connecting part 221 of the slider 220, and the outer base protrusion 212 is rotatably connected to one end of a rocker arm 230. The other end of the rocker arm 230 is rotatably connected to the outer end of the frame 240. It can be understood that there are four rocker arms 230, with each rocker arm 230 connected to one finger base connecting rod.

[0044] In some specific embodiments of the present invention, see Figure 2 and Figure 3The slider 220 includes a connecting part 221 and a limiting part 222. The connecting part 221 is a hollow, rectangular structure. The optical axis 250 passes through the through hole of the connecting part 221 and is fixedly connected to the lower center of the limiting part 222. The connecting part 221 is provided with four connecting protrusions, two of which are symmetrically arranged on the front side of the connecting part 221, and the other two are symmetrically arranged on the rear side of the connecting part 221. The inner side of the connecting protrusions is fixedly connected to the center of the limiting part 222, and the outer side of the connecting protrusions is rotatably connected to the finger base connecting rod 210. The limiting part 222 has a V-shaped structure. The left and right sides of the limiting part 222 are located between the two finger base connecting rods, and the left and right sides of the limiting part 222 extend outward to contact the limiting rod 243.

[0045] In some specific embodiments of the present invention, see Figure 2 and Figure 3 The frame 240 includes a central connecting plate 241, four protruding ends 242, and two limiting rods 243. The central connecting plate 241 has a roughly square structure. The four protruding ends 242 are respectively located at the four corners of the central connecting plate 241, and the outer sides of the four ends are rotatably connected to four rocker arms 230. The optical axis 250 movably passes through the central connecting plate 241 and is connected to the slider 220. It should be noted that a copper-graphite bearing is connected between the optical axis 250 and the central connecting plate 241, allowing the optical axis 250 to slide up and down relative to the frame 240, achieving precise linear guidance. Furthermore, the two limiting rods 243 are located on the side of the central connecting plate 241 facing away from the drive mechanism 300, i.e., see [reference needed]. Figure 3 The two limiting rods 243 shown are higher than the intermediate connecting plate 241. The front end and rear end of one limiting rod 243 are connected to the inner side of the two protruding ends 242 on the left side, respectively. The front end and rear end of the other limiting rod 243 are connected to the inner side of the two protruding ends 242 on the right side, respectively. When the driving mechanism 300 drives the optical axis 250 and the slider 220 to move downward to a certain position, the limiting part 222 contacts the limiting rod 243, which restricts the optical axis 250 and the slider 220 from moving further downward. At this time, the flexible manipulator closes, and the two fingertip blocks 110 just cross. At the same time, it prevents the flexible manipulator from closing too much, which would cause the two finger blocks 110 to collide and be damaged.

[0046] In some specific embodiments of the present invention, two rectangular connecting frames 260 are provided, and the two rectangular connecting frames 260 are symmetrically arranged on the left and right sides of the drive housing 360 of the drive mechanism 300, see [reference]. Figure 2 The rectangular connecting frame 260 is placed vertically. The upper side of the rectangular connecting frame 260 is fixedly connected to the middle connecting plate 241 of the frame 240, and the lower side of the rectangular connecting frame 260 is fixedly connected to the drive box 360. The optical axis 250 is set between the two rectangular connecting frames 260.

[0047] In some embodiments of the present invention, the drive mechanism 300 employs an adaptive variable transmission ratio drive method, providing an adaptively adjustable linear driving force to the flexible finger 100 via the optical axis 250 of the robotic arm transmission mechanism 200. See also Figure 2 The drive mechanism 300 includes a drive housing 360. A robotic arm transmission mechanism and a driver 370 are respectively connected to the upper and lower sides of the drive housing 360. A first lead screw 310, a second lead screw 320, a first nut 330, a second nut 340, and a constant torque preload device 350 are all disposed within the drive housing 360. Specifically, the drive mechanism 300 includes a first guide rail 322, a first slider 323, a second slider 354, and a second guide rail 353. The first guide rail 322 and the second guide rail 353 are fixedly disposed on the inner side wall of the drive housing 360. The first slider 323 is slidably disposed on the first guide rail 322, and the second slider 354 is slidably disposed on the second guide rail 353. The first slider 323 is fixedly connected to the second nut 340, and the second slider 354 is connected to the constant torque preload device 350. It should be noted that the first guide rail 322 is used to achieve the first lead, and the second guide rail 353 is used to achieve the second lead.

[0048] In some specific embodiments of the present invention, the drive mechanism 300 further includes a nut connecting block 324, which is fixedly connected to the second slider 354 and the second nut 340 respectively. See also Figure 2 and Figure 4 The nut connecting block 324 includes a vertical nut connecting plate and a horizontal nut connecting plate that are perpendicular to each other. The vertical nut connecting plate is fixedly connected to the second slider 354, and the lower side of the horizontal nut connecting plate is fixedly connected to the second nut 340. This invention restricts the rotation of the second nut 340, allowing it to move linearly along the axial direction of the second lead screw 320, and serves as the final output end of the entire drive mechanism 300. Furthermore, the upper side of the horizontal nut connecting plate is fixedly connected to the lower side of the output end flange 321, and the upper side of the output end flange 321 is fixedly connected to the optical axis 250.

[0049] In some specific embodiments of the present invention, the drive mechanism 300 further includes a pre-tightening device connecting block 355, which is fixedly connected to the second slider 354 and the constant torque pre-tightening device. See also Figure 2 and Figure 5The preload device connecting block 355 includes a vertical connecting plate and a horizontal connecting plate that are perpendicular to each other. The vertical connecting plate is fixedly connected to the second slider 354, and the horizontal connecting plate is fixedly connected to the lower side of the constant torque damping turntable 351. The upper side of the constant torque damping turntable 351 is fixedly connected to the shaft end fixing flange 352, which is sleeved on the first lead screw 310. This invention, through the cooperation of the preload device connecting block 355 and the second slider 354 for realizing the second lead, allows the constant torque preload device 350 to move axially linearly with the lead screw assembly (composed of the first lead screw 310 and the second lead screw 320), while simultaneously restricting the rotation of the constant torque preload device 350. This allows the constant torque preload device 350 to provide a preset, constant preload torque to the first lead screw 310 that resists its rotation.

[0050] Furthermore, there are two nut connecting vertical plates and two first sliders 323, two device connecting vertical plates, two second sliders 354, and two drive boxes 360 with a cuboid structure. The two first sliders 323 are located on two adjacent side walls of the drive box 360, and the two second sliders 354 are located on the other two adjacent side walls of the drive box 360.

[0051] In some specific embodiments of the present invention, see Figure 2 and Figure 6 The drive mechanism 300 also includes a bearing mounting base 312 and a nut bearing 313. The bearing mounting base 312 is fixedly disposed on the inner side wall of the drive housing 360. The nut bearing 313 is disposed between the bearing mounting base 312 and the first nut 330. The first nut 330 can move linearly relative to the drive housing 360 but cannot rotate. The first nut 330 is threadedly connected to the first lead screw 310, allowing the first lead screw 310 to move linearly relative to the first nut 330. Further, a nut retaining ring 314 and a nut limiting ring 315 are respectively provided on the upper and lower sides of the nut bearing 313. Both the nut retaining ring 314 and the nut limiting ring 315 are sleeved on the first lead screw 310. Through the cooperation of the bearing mounting base 312, the nut retaining ring 314, and the nut limiting ring 315, the present invention ensures that the first nut 330 can only rotate and cannot move axially. It is understood that the nut bearing 313 in this embodiment of the invention can be a deep groove ball bearing.

[0052] A specific embodiment is described here.

[0053] The working principle of the flexible manipulator in the rapid, low-force closing state is as follows: When the flexible manipulator begins to grasp an object, the driver 370 rotates, causing the input flange 311 to rotate, which in turn drives the first lead screw 310 and the first nut 330 to rotate. At this time, because the flexible manipulator is unloaded or experiences very little resistance, the reaction torque acting on the first lead screw 310 is less than the pre-tightening torque preset by the fixed torque pre-tightening device 350. The first lead screw 310 is locked by the fixed torque pre-tightening device 350, so that the rotation trend of the combined lead screw formed by the connection of the first lead screw 310 and the second lead screw 320 is suppressed by the fixed torque pre-tightening device 350, and the combined lead screw remains stationary. At the same time, the first nut 330 remains unsuppressed and rotates. Through the first lead (e.g., 18mm), the combined lead screw is driven to perform a rapid, low-force linear motion (non-rotation). This rapid, low-force motion is transmitted to the optical shaft 250 through the second nut 340 and the output flange 321, causing the flexible finger 100 to close rapidly.

[0054] It should be noted that the constant torque preload device 350 is used to restrict the rotation of the combined lead screw consisting of the first lead screw 310 and the second lead screw 320, but does not restrict the linear movement of the combined lead screw extending or retracting into the drive box 360. When the first lead screw 310 does not rotate but the first nut 330 rotates, because the first nut 330 is fixed in the drive box 360 by the bearing mounting seat and can only rotate and cannot move up and down, and because the first nut 330 and the second nut 340 are threadedly connected, the first lead screw 310 moves downward linearly under the rotation of the first nut 330. The first lead screw 310 drives the second lead screw 320 to move downward linearly through the coupling 316. At the same time, the constant torque preload device moves downward linearly along the second guide rail 353, and the second nut 340 and the output end flange 321 move downward linearly along the first guide rail 322, thereby causing the optical axis 250 to move downward linearly, driving the flexible finger 100 to close.

[0055] The working principle of the flexible robotic arm in a slow-strong-grip state is as follows: When the flexible finger 100 contacts an object and begins to apply gripping force, the external load of the flexible robotic arm increases. This increases, and through the transmission mechanism, it reacts on the combined lead screw, generating a reaction torque. When this reaction torque reaches or exceeds the pre-tightening torque threshold set by the constant torque pre-tightening device 350, the constant torque damping disc begins to slip, and the rotation constraint on the first lead screw 310 fails. At this time, the rotation of the first nut 330 drives the first lead screw 310 and the second lead screw 320 to rotate together through thread engagement. Since the rotation of the second nut 340 is restricted by the first guide rail 322 and the second guide rail 353, the rotation of the combined lead screw drives the second nut 340 to perform a slow but significantly amplified linear motion through the second lead (e.g., 1 mm). This slow, small-force motion is transmitted to the optical shaft 250 through the output flange 321, allowing the flexible finger 100 to perform a stable and strong grip.

[0056] Specifically, when the constant torque preload device 350 cannot suppress the rotation of the first lead screw 310, the first nut 330 is threadedly connected to the first lead screw 310, and the first nut 330 can drive the first lead screw 310 and the second lead screw 320 to rotate together. At the same time, the second nut 340, which is connected to the first guide rail 322, cannot rotate and can only move linearly. The second lead screw 320 is threadedly connected to the second nut 340, and the second nut 340 moves downward along the first guide rail 322 under the rotation of the second lead screw 320. This causes the constant torque preload module to move downward along the second guide rail 353, and also causes the output flange 321 and the optical axis 250 to move downward, thereby driving the flexible finger 100 to close.

[0057] This invention improves the mechanical design of the drive mechanism 300 and, in conjunction with a constant torque preload device, achieves adaptive adjustment of the gripping force of the flexible robotic arm, automatically optimizing its force-speed output characteristics under different working conditions.

[0058] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure, as long as they achieve the technical effects of the present invention by the same means, should be included within the scope of protection of this disclosure. Within the scope of protection of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A flexible robotic arm, characterized in that, include: A flexible finger (100) for grasping an object and a robotic arm transmission mechanism (200) for driving the flexible finger (100) to open and close to grasp the object, and a drive mechanism (300) for providing a first lead and a second lead for grasping linear driving force and allowing adaptive variable transmission ratio, wherein the robotic arm transmission mechanism (200) is connected to the flexible finger (100) and the drive mechanism (300) respectively. The drive mechanism (300) includes a drive housing (360), a first lead screw (310), a second lead screw (320), a first nut (330), a second nut (340), and a constant torque preload device (350). The first lead screw (310) is fixedly connected to the second lead screw (320), the first lead screw (310) is threadedly connected to the first nut (330), the first nut (330) is fixedly connected to the input flange (311), the input flange (311) is fixedly connected to the output shaft (371) of the driver (370), the second lead screw (320) is threadedly connected to the second nut (340), and the second nut (340) is fixedly connected to the manipulator transmission mechanism (200). The constant torque preload device (350) is slidably connected to the drive housing (360) to allow the constant torque preload device (350) to move linearly and restrict its rotation. The constant torque preload device (350) provides a preset constant preload torque for limiting the rotation of the first lead screw (310), and the first nut (330) is rotatably connected to the drive box (360) to allow the first nut (330) to rotate and limit its linear motion, thereby allowing the generation of a gripping driving force of the flexible finger (100) based on the first lead. The second nut (340) is slidably connected to the drive box (360) to allow the second nut (340) to move linearly and restrict its rotation, thereby allowing the generation of a gripping drive force of the flexible finger (100) based on the second lead.

2. The flexible robotic arm according to claim 1, characterized in that, The constant torque preload device (350) includes a constant torque damping turntable (351), which is connected to the first lead screw (310) via a shaft end fixing flange (352).

3. The flexible robotic arm according to claim 1, characterized in that, The drive mechanism (300) further includes a first guide rail (322) and a first slider (323) that match the first lead, and a second guide rail (353) and a second slider (354) that match the second lead. The first guide rail (322) and the second guide rail (353) are fixedly disposed on the inner side wall of the drive box (360). The first slider (323) is movably disposed on the first guide rail (322), and the second slider (354) is movably disposed on the second guide rail (353). The first slider (323) is fixedly connected to the second nut (340), and the second slider (354) is fixedly connected to the constant torque preload device (350).

4. The flexible robotic arm according to claim 3, characterized in that, The drive mechanism (300) further includes a nut connecting block (324) and a pre-tightening device connecting block (355). The nut connecting block (324) is fixedly connected to the second slider (354) and the second nut (340) respectively. The pre-tightening device connecting block (355) is fixedly connected to the second slider (354) and the constant torque pre-tightening device (350) respectively.

5. The flexible robotic arm according to claim 3, characterized in that, The robotic arm transmission mechanism (200) includes a finger base connecting rod (210), a slider (220), a rocker arm (230), and a frame (240). The finger base connecting rod (210) is fixedly connected to the flexible finger (100). The inner side of the finger base connecting rod (210) is rotatably connected to the slider (220). The outer side of the finger base connecting rod (210) is rotatably connected to the upper side of the rocker arm (230). The lower side of the rocker arm (230) is rotatably connected to the frame (240).

6. The flexible robotic arm according to claim 5, characterized in that, The robotic arm transmission mechanism (200) also includes an optical axis (250) and a rectangular connecting frame (260). The upper side of the optical axis (250) is fixedly connected to the slider (220), and the two sides of the rectangular connecting frame (260) are fixedly connected to the frame (240) and the drive box (360) respectively. The slider (220) includes a connecting part (221) and a limiting part (222). The connecting part (221) is fixedly connected to the limiting part (222), and the connecting part (221) is rotatably connected to the finger base connecting rod (210). The limiting part (222) is fixedly connected to the optical axis (250). The frame (240) is provided with a limiting rod (243) that allows contact with the limiting part (222) to limit the closure of the flexible finger (100).

7. The flexible robotic arm according to claim 3, characterized in that, The drive mechanism (300) further includes a bearing mounting base (312), a nut bearing (313), a nut retaining ring (314), and a nut limiting ring (315). The bearing mounting base (312) is fixedly connected to the drive box (360). The nut bearing (313) is disposed between the bearing mounting base (312) and the first nut (330). The nut retaining ring (314) and the nut limiting ring (315) are respectively disposed on both sides of the nut bearing (313).

8. The flexible robotic arm according to claim 6, characterized in that, The second lead screw (320) is fixedly connected to an output flange (321) at the end away from the first lead screw (310), and the output flange (321) is fixedly connected to the optical axis (250); the first lead screw (310) is fixedly connected to an input flange (311) at the end away from the second lead screw (320), and the input flange (311) is fixedly connected to the output shaft (371) of the driver (370).

9. The flexible robotic arm according to claim 1, characterized in that, The flexible finger (100) includes a double fingertip block (111) and a single fingertip block (112) that allow partial crossing to form a closed grasping space.

10. A method for operating a flexible robotic hand with adaptive gripping force, characterized in that, Applied to the flexible robotic hand with adaptive gripping force as described in any one of claims 1 to 9, the method comprises the following steps: When the reaction torque of the gripping load on the flexible manipulator is lower than the preset torque threshold, the first nut (330) is rotated by the driver (370), and the first lead screw (310) and the second lead screw (320) move linearly with the first lead in the state where the first lead screw (310) is restricted from rotating by the fixed torque preload device (350). When the reaction torque of the gripping load on the flexible manipulator reaches or exceeds the preset torque threshold, the first nut (330) is rotated and the first lead screw (310) and the second lead screw (320) are rotated through thread engagement. In the state where the second nut (340) is restricted and does not rotate, the second nut (340) moves linearly with the second lead.

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