Flexible manipulator with adaptive gripping force and operation method thereof

Abstract

The present application relates to a flexible manipulator with self-adaptive gripping force and its operation method, which comprises flexible fingers, a transmission mechanism and a driving mechanism. The driving mechanism adopts a first screw rod and a second screw rod in series and is provided with a fixed torque pre-tightening device. When the load is low, the driving mechanism limits the rotation of the first screw rod and the second screw rod, so that the manipulator is quickly closed with a first large lead. When the load is high, the first screw rod and the second screw rod rotate to overcome the pre-tightening torque, so that the flexible manipulator is slowly gripped with a second small lead. The present application can solve the problem that the existing manipulator is difficult to balance fast movement and large force output. The automatic and passive switching of force-speed characteristics is realized through a pure mechanical structure. The structure is compact, the control is simple, the reliability is high, and the adaptability of the manipulator to different gripping tasks is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a flexible manipulator with adaptive gripping force and an operating method thereof, and belongs to the technical field of manipulators. BACKGROUND

[0002] In the fields of industrial automation, special operation robots, and service robots, a manipulator as an execution end, its grasping and operating ability is crucial. An ideal manipulator should be able to adapt to objects of different sizes, shapes, and stiffness, and exhibit different performance in different task stages. For example, when quickly approaching a target object, the manipulator needs to be quickly closed to improve work efficiency; while when stably holding an object or applying an operating force, the manipulator needs to be able to provide a large and stable gripping force to ensure the reliability of the operation.

[0003] The existing manipulator design scheme usually cannot balance the two contradictory requirements of fast motion and large force output. If a manipulator driven by a fixed transmission ratio is selected to have a large reduction ratio in order to obtain a large gripping force, its opening and closing speed will be slow, affecting the efficiency; on the contrary, if a small reduction ratio is selected in order to improve the speed, the output force will be insufficient. In order to solve this problem, some designs use complex electromechanical systems, such as by adding additional motors, clutches, and gearboxes to switch different transmission ratios, but this undoubtedly increases the volume, weight, cost of the manipulator, and the complexity of the control system, reducing the reliability of the system.

[0004] In addition, for a flexible manipulator, its fingers usually have a certain flexibility to adapt to irregular objects, such as bionic fin structures. However, its driving mechanism is mostly still a traditional rigid transmission, which has not fundamentally solved the problem of adaptive adjustment of force-speed characteristics. SUMMARY

[0005] The present application provides a flexible manipulator with adaptive gripping force and an operating method thereof, aiming to at least solve one of the technical problems existing in the prior art. To this end, the flexible manipulator with adaptive gripping force and the operating method thereof proposed by the present application have a compact structure and simple control, and can automatically and passively adjust the output characteristics according to the actual grasping load.

[0006] The technical scheme of the present application is related to a flexible manipulator, comprising:

[0007] a flexible finger for grasping an object and a manipulator transmission mechanism for driving the flexible finger to open and close to grasp the object, and a driving mechanism 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 being connected with the flexible finger and the driving mechanism respectively;

[0008] The driving mechanism comprises a driving box, a first screw rod, a second screw rod, a first nut, a second nut and a constant torque pre-tightening device, the first screw rod is fixedly connected with the second screw rod, the first screw rod is threadedly connected with the first nut, the first nut is fixedly connected with an input flange, the input flange is fixedly connected with an output shaft of a driver, the second screw rod is threadedly connected with the second nut, and the second nut is fixedly connected with the mechanical hand transmission mechanism; the constant torque pre-tightening device is slidably connected with the driving box to allow linear movement of the constant torque pre-tightening device and limit rotation thereof;

[0009] The constant torque pre-tightening device provides a preset constant pre-tightening torque for limiting rotation of the first screw rod, the first nut is rotatably connected with the driving box to allow rotation of the first nut and limit linear movement thereof, thereby allowing generation of a gripping driving force of the flexible finger based on a first lead;

[0010] The second nut is slidably connected with the driving box to allow linear movement of the second nut and limit rotation thereof, thereby allowing generation of a gripping driving force of the flexible finger based on a second lead.

[0011] Further, the constant torque pre-tightening device comprises a constant torque damping turntable connected with the first screw rod through an axial end fixing flange.

[0012] Further, the driving mechanism further comprises a first guide rail and a first sliding block matched with the first lead, and a second guide rail and a second sliding block matched with the second lead, the first guide rail and the second guide rail are fixedly arranged on the inner side of the side wall of the driving box, the first sliding block is movably arranged on the first guide rail, the second sliding block is movably arranged on the second guide rail, the first sliding block is fixedly connected with the second nut, and the second sliding block is fixedly connected with the constant torque pre-tightening device.

[0013] Further, the driving mechanism further comprises a nut connecting block and a pre-tightening device connecting block, the nut connecting block is fixedly connected with the second sliding block and the second nut respectively, and the pre-tightening device connecting block is fixedly connected with the second sliding block and the constant torque pre-tightening device respectively.

[0014] Further, the mechanical hand transmission mechanism comprises a finger base connecting rod, a sliding block, a rocker and a rack, the finger base connecting rod is fixedly connected with the flexible finger, the inner side of the finger base connecting rod is rotatably connected with the sliding block, the outer side of the finger base connecting rod is rotatably connected with the upper side of the rocker, and the lower side of the rocker is rotatably connected with the rack.

[0015] Further, the mechanical hand transmission mechanism further comprises an optical shaft and a rectangular connecting frame, the upper side of the optical shaft is fixedly connected with the sliding block, and the two sides of the rectangular connecting frame are fixedly connected with the rack and the driving box respectively.

[0016] Further, the sliding block comprises a connecting part and a limiting part, the connecting part is fixedly connected with the limiting part, the connecting part is rotatably connected with the finger base connecting rod, and the limiting part is fixedly connected with the optical shaft; the rack is provided with a limiting rod allowing contact with the limiting part to limit the closing of the flexible finger.

[0017] Further, the driving mechanism further comprises a bearing mounting base, a nut bearing, a nut stop ring and a nut limiting ring, the bearing mounting base is fixedly connected with the driving box, the nut bearing is arranged between the bearing mounting base and the first nut, and the nut stop ring and the nut limiting ring are arranged on the two sides of the nut bearing respectively.

[0018] Further, the second screw rod is fixedly connected with an output end flange at the end away from the first screw rod, and the output end flange is fixedly connected with the optical shaft; the first screw rod is fixedly connected with an input end flange at the end away from the second screw rod, and the input end flange is fixedly connected with the output shaft of the driver.

[0019] Further, the flexible finger comprises double-finger tip blocks and single-finger tip blocks allowing partial intersection to form a closed gripping space.

[0020] The technical scheme of the present application further relates to an operation method of the flexible mechanical hand with adaptive gripping force, which is applied to the flexible mechanical hand with adaptive gripping force in the above-mentioned embodiments of the present application, and comprises the following steps.

[0021] When the reaction torque of the gripping load borne by the flexible mechanical hand is lower than the preset torque threshold, the first nut is rotated by the driver, and the first screw rod and the second screw rod are made to move linearly at a first lead in the state that the first screw rod is not rotated under the limitation of the torque pre-tightening device.

[0022] When the reaction torque of the gripping load borne by the flexible mechanical hand reaches or exceeds the preset torque threshold, the first nut is rotated and drives the first screw rod and the second screw rod to rotate through thread engagement, and the second nut is made to move linearly at a second lead in the state that the second nut is not rotated.

[0023] The present application has the following beneficial effects.

[0024] The flexible manipulator with adaptive gripping force and the operation method thereof have the advantages of compact structure, reliable transmission, automatic switching between fast small force closing mode and slow large force gripping mode according to the gripping force, and adaptive gripping force. The driving mechanism can automatically and passively switch between the fast small force mode and the slow large force mode according to the actual gripping load, realizes the intrinsic intelligence at the mechanical level, and improves the adaptability to different objects. The two transmission ratios are integrated in a series screw system, the switching is realized through a torque pre-tightening device, compared with the scheme using multiple gear trains and clutches, the structure is simpler, the volume is more compact, the failure points are fewer, and the reliability is higher. Before contacting the object, the manipulator can quickly close by using the large lead mode, the non-working stroke time is shortened, and the overall operation efficiency is improved. When a large gripping force is required, the system automatically switches to the small lead large force mode, can provide stable and reliable clamping force, and prevents the object from slipping or operation failure. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:

[0026] Figure 1 FIG. 1 is a schematic diagram of the overall structure of the flexible manipulator according to the present application.

[0027] Figure 2 FIG. 2 is a structural sectional view of the flexible manipulator according to the present application.

[0028] Figure 3 FIG. 3 is an enlarged schematic view of A of FIG. 1. Figure 1

[0029] Figure 4 FIG. 4 is a schematic diagram of the connection structure of the second screw rod and the second nut according to the present application.

[0030] Figure 5 FIG. 5 is a schematic diagram of the connection structure of the fixed torque pre-tightening device according to the present application.

[0031] Figure 6 FIG. 6 is a schematic diagram of the connection structure of the first screw rod and the first nut according to the present application.

[0032] Figure 7 FIG. 7 is a schematic diagram of the closed state of the flexible manipulator according to the present application.

[0033] Figure 8 FIG. 8 is a schematic diagram of the open state of the flexible manipulator according to the present application.

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] ​100, flexible finger; 110, finger block; 111, double finger tip block; 112, single finger tip block;

[0036] 200, mechanical hand transmission mechanism; 210, finger base connecting rod; 211, base connecting plate; 212, base protruding rod; 220, sliding block; 221, connecting part; 222, limiting part; 230, rocker; 240, frame; 241, intermediate connecting plate; 242, protruding end part; 243, limiting rod; 250, optical axis; 260, rectangular connecting frame;

[0037] 300, driving mechanism; 310, first screw rod; 311, input end flange; 312, bearing mounting base; 313, nut bearing; 314, nut stop ring; 315, nut limiting ring; 316, shaft coupling; 320, second screw rod; 321, output end flange; 322, first guide rail; 323, first sliding block; 324, nut connecting block; 330, first nut; 340, second nut; 350, constant torque pre-tightening device; 351, constant torque damping turntable; 352, shaft end fixing flange; 353, second guide rail; 354, second sliding block; 355, pre-tightening device connecting block; 360, driving box; 370, driver; 371, output shaft. DETAILED DESCRIPTION

[0038] The concept, specific structure and generated technical effects of the present application will be described clearly and completely in combination with embodiments and drawings, so as to fully understand the purpose, scheme and effects of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0039] It should be noted that, unless otherwise specified, when a certain feature is referred to as being "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. In addition, the up, down, left, right, top, bottom and the like used in the present application are only relative to the relative position of each component of the present application in the drawings.

[0040] In addition, 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 terms used in the specification herein are only for describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any combination of one or more related listed items.

[0041] It should be understood that, although the terms first, second, third, etc. can be employed in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish one type of element from another. For example, a first element could also be termed a second element, and, similarly, a second element could also be termed a first element without departing from the scope of this disclosure.

[0042] Referring to Figures 1 to 8 , the flexible manipulator with adaptive gripping force comprises flexible fingers 100 for gripping objects, a manipulator transmission mechanism 200 for driving the flexible fingers 100 to open and close to grip objects, and a driving mechanism 300 for providing a gripping linear driving force with a first lead and a second lead and allowing adaptive variable transmission ratio, and the manipulator transmission mechanism 200 is connected with the flexible fingers 100 and the driving mechanism 300 respectively. The driving mechanism 300 comprises a driving box 360, a first lead screw 310, a second lead screw 320, a first nut 330, a second nut 340 and a constant torque pre-tightening device 350, the first lead screw 310 is fixedly connected with the second lead screw 320, the first lead screw 310 is threadedly connected with the first nut 330, the first nut 330 is fixedly connected with an input flange 311, the input flange 311 is fixedly connected with an output shaft 371 of a driver 370, the second lead screw 320 is threadedly connected with the second nut 340, and the second nut 340 is fixedly connected with the manipulator transmission mechanism 200; the constant torque pre-tightening device 350 is slidably connected with the driving box 360 to allow linear movement of the constant torque pre-tightening device 350 and limit its rotation. Wherein, the constant torque pre-tightening device 350 provides a preset constant pre-tightening torque for limiting the rotation of the first lead screw 310, the first nut 330 is rotatably connected with the driving box 360 to allow the rotation of the first nut 330 and limit its linear movement, thereby allowing the gripping driving force of the flexible fingers 100 based on the first lead to be generated. Wherein, the second nut 340 is slidably connected with the driving box 360 to allow linear movement of the second nut 340 and limit its rotation, thereby allowing the gripping driving force of the flexible fingers 100 based on the second lead to be generated.

[0043] Referring to Figure 1 and Figure 2 , the flexible manipulator comprises flexible fingers 100, a manipulator transmission mechanism 200 and a driving mechanism 300 allowing adaptive variable transmission ratio, the upper side and the lower side of the manipulator transmission mechanism 200 are connected with the flexible fingers 100 and the driving mechanism 300 respectively, and the lower side of the driving mechanism 300 is connected with a driver 370, which drives the driving mechanism 300 to move to close the flexible fingers 100. It can be understood that the driver 370 used to provide gripping of the flexible manipulator in the embodiment of the present application can be a rotary motor, a servo motor and the like.

[0044] Specifically, the driving mechanism 300 comprises a first screw rod 310, a first nut 330, a second screw rod 320 and a second nut 340, the first nut 330 is sleeved on the first screw rod 310, the second nut 340 is sleeved on the second nut 340, the lower side of the second screw rod 320 is fixedly connected with the upper side of the first screw rod 310 through a shaft coupling 316, the upper side of the second screw rod 320 is threadedly connected with the second nut 340, the second nut 340 is fixedly connected with the lower side of an output flange 321, the upper side of the output flange 321 is fixedly connected with the mechanical arm transmission mechanism 200. The lower side of the first screw rod 310 is threadedly connected with the first nut 330, the first nut 330 is fixedly connected with an input flange 311, the input flange 311 is fixedly connected with an output shaft 371 of a driver 370, and the first screw rod 310 is connected with a constant torque pre-tightening device 350. Further, the first screw rod 310 and the second screw rod 320 are coaxially and rigidly connected through a single diaphragm shaft coupling 316, forming a functionally series-connected “combined screw rod”.

[0045] The operation method of the flexible manipulator with adaptive gripping force comprises at least the following steps:

[0046] When the reaction torque of the grasping load received by the flexible manipulator is lower than the preset torque threshold, the first nut 330 is rotated by the driver 370, and the first screw rod 310 and the second screw rod 320 are subjected to fast and small force linear motion with the first lead in the state that the first screw rod 310 is not rotated under the limitation of the constant torque pre-tightening device 350;

[0047] When the reaction torque of the grasping load received by the flexible manipulator reaches or exceeds the preset torque threshold, the first nut 330 is rotated and drives the first screw rod 310 and the second screw rod 320 to rotate through thread engagement, and the second nut 340 is subjected to slow and large force linear motion with the second lead in the state that the second nut 340 is not rotated.

[0048] According to the size of the load grasped by the flexible finger 100 (i.e. the size of the driving force required for grasping the object), the grasping driving force is provided by the first lead and the second lead respectively, wherein the first lead is greater than the second lead. Specifically, the torque pre-tightening device 350 of the present application provides a preset constant pre-tightening torque for inhibiting the rotation of the first screw rod 310. When the reaction torque formed on the first screw rod 310 by the axial load generated when the flexible manipulator is grasping is less than the pre-tightening torque, the first screw rod 310 does not rotate, the first nut 330 rotates and cannot move linearly, thereby driving the combined screw rod formed by the first screw rod 310 and the second screw rod 320 to produce fast and small force linear movement based on the first lead, providing fast and small force grasping driving force for the flexible finger 100. When the reaction torque reaches or exceeds the pre-tightening torque, the first screw rod 310 can rotate against the constraint of the torque pre-tightening device 350, the first screw rod 310 drives the second screw rod 320 to rotate, while the second nut 340 can only move linearly and cannot rotate, thereby driving the second nut 340 to produce slow and large force linear movement based on the second lead, providing slow and large force grasping driving force for the flexible finger 100.

[0049] The flexible manipulator with adaptive grasping force of the present application realizes automatic and passive switching of force-speed characteristics through a pure mechanical structure, has the advantages of compact structure, fast response, high energy efficiency, no need for complex switching control, etc., and significantly improves the adaptability of the manipulator to different grasping tasks. The driving mechanism 300 of the present application can automatically and passively switch between the fast and small force mode and the slow and large force mode according to the actual grasping load, realizes intrinsic intelligence at the mechanical level, and improves the adaptability to different objects. The present application integrates two transmission ratios in a series of screw rod systems, and realizes switching through a torque pre-tightening device. Compared with the scheme using multiple gear trains and clutches, the structure is simpler, the volume is more compact, the failure points are fewer, and the reliability is higher. Before contacting the object, the manipulator can use the large lead mode to close fast and small (first lead), which shortens the non-working stroke time and improves the overall work efficiency. When a larger grasping force is needed, the system automatically switches to the small lead and large force mode (second lead), which can provide stable and reliable clamping force to prevent the object from slipping or the operation from failing.

[0050] In some embodiments of the present application, the flexible finger 100 of the present application adopts a bionic fin structure, and the rib structure enables it to generate an envelope surface when contacting the target object, having good shape adaptability. Specifically, the flexible finger 100 of the embodiment of the present application includes a double-tip finger block 111 and a single-tip finger block 112. When the flexible manipulator is closed, the single-tip finger block 112 can be inserted between the two tips of the double-tip finger block 111, so that the double-tip finger block 111 and the single-tip finger block 112 partially intersect, thereby forming a closed grasping space.

[0051] Referring to Figure 1 and Figure 3 , the flexible finger 100 comprises two fingertip blocks 110, which are conical and have inwardly curved tips, and the two fingertip blocks 110 can partially cross to form a closed gripping space. Further, to enhance the gripping ability, one of the fingertip blocks 110 is a double fingertip block 111, and the other fingertip block 110 is a single fingertip block 112, referring to Figure 7 and Figure 8 , when the two fingertip blocks 110 move away from each other, the flexible mechanical hand opens the palm, and when the two fingertip blocks 110 move towards each other, the flexible mechanical hand closes the palm, at which time the flexible mechanical hand can hold an object. Referring to Figure 3 , the two tips of the double fingertip block 111 are spaced apart, and 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 on the mechanical hand transmission mechanism 200 by a finger screw.

[0052] In some embodiments of the present application, the mechanical hand transmission mechanism 200 of the embodiments of the present application is a planar rocker 230 slider 220 mechanism, which comprises a finger base connecting rod 210, a slider 220, a rocker 230, and a rack 240, the finger base connecting rod 210 is fixedly connected with the flexible finger 100, the inner side of the finger base connecting rod 210 is rotatably connected with the slider 220, the outer side of the finger base connecting rod 210 is rotatably connected with the upper side of the rocker 230, the lower side of the rocker 230 is rotatably connected with the rack 240, further, the mechanical hand transmission mechanism 200 further comprises an optical axis 250 and a connecting frame, the upper side of the optical axis 250 is fixedly connected with the slider 220, the optical axis 250 is fixedly connected with the second lead screw 320 through the output flange 321 of the driving mechanism 300, the upper side of the connecting frame is fixedly connected with the rack 240, and the lower side of the connecting frame is fixedly connected with the driving box 360 of the driving mechanism 300. Further, the slider 220 comprises a connecting portion 221 and a limiting portion 222, the connecting portion 221 is fixedly connected with the limiting portion 222, and the rack 240 is provided with a limiting rod 243 which allows contact with the limiting portion 222 to limit the closing of the flexible finger 100.

[0053] Specifically, referring to Figure 3 and Figure 7 , when the driving mechanism 300 drives the optical axis 250 to move downward, the optical axis 250 drives the slider 220 to move downward, so that the inner side of the finger base connecting rod 210 and the inner side of the flexible finger 100 move downward, and the upper end of the rocker 230 rotates inwardly, and at the same time, under the cooperation of the rack 240, the tips of the two fingertip blocks 110 of the flexible finger 100 move inwardly towards each other, so that the flexible mechanical hand can grip an object. Referring toFigure 3 and Figure 8 When the driving mechanism 300 drives the optical shaft 250 to move upward, the optical shaft 250 drives the slider 220 to move upward, so that the inner side of the finger base connecting rod 210 and the inner side of the flexible finger 100 move upward, and the upper end of the rocker 230 rotates outward, and under the cooperation of the frame 240, the tips of the two finger blocks 110 of the flexible finger 100 move outward and backward, so that the flexible robot hand can release the object.

[0054] It should be noted that the top plate of the driving box 360 of the driving mechanism 300 is provided with an output hole, and the diameter of the output flange 321 and the optical shaft 250 is smaller than the diameter of the output hole, so that the output flange 321 and the optical shaft 250 are spaced apart from the driving box 360, thereby allowing the output flange 321 and the optical shaft 250 to move through the output hole. Further, the bottom plate of the driving box 360 of the driving mechanism 300 is provided with an input hole, and the diameter of the input flange 311 and the output shaft 371 of the driver 370 is smaller than the diameter of the input hole, so that the input flange 311 is spaced apart from the driving box 360, thereby allowing the input flange 311 to rotate through the input hole.

[0055] In some embodiments of the present application, four finger base connecting rods 210 are provided, as shown in Figure 3 Two finger blocks 110 are respectively arranged on the left side and the right side of the flexible robot hand, wherein two finger base connecting rods 210 are respectively connected to the front side and the back side of the finger block 110 on the left side, and the other two finger base connecting rods 210 are respectively connected to the front side and the back side of the finger block 110 on the right side. Specifically, the finger base connecting rod includes a base connecting plate 211 and two base protruding rods 212, the upper side of the base connecting plate 211 is connected to the bottom surface of the flexible finger 100, and the two base protruding rods 212 are respectively arranged on the outer side and the inner side of the lower end of the base connecting plate 211. The base protruding rod 212 on the inner side is rotationally connected to the connecting part 221 of the slider 220, and the base protruding rod 212 on the outer side is rotationally connected to one end of the rocker 230, and the other end of the rocker 230 is rotationally connected to the outer end of the frame 240. It can be understood that four rockers 230 are provided, and one rocker 230 is connected to one finger base connecting rod.

[0056] In some embodiments of the present application, as shown in Figure 2 and Figure 3The slider 220 comprises a connecting portion 221 and a limiting portion 222. The connecting portion 221 is a hollow rectangular structure, and the optical axis 250 is fixedly connected to the lower middle portion of the limiting portion 222 through the through hole of the connecting portion 221. The connecting portion 221 is provided with four connecting tabs, two of which are symmetrically arranged on the front side of the connecting portion 221, and the other two are symmetrically arranged on the rear side of the connecting portion 221. The inner side of the connecting tab is fixedly connected to the middle portion of the limiting portion 222, and the outer side of the connecting tab is rotatably connected to the finger base connecting rod 210. The limiting portion 222 is a V-shaped structure, and the left and right sides of the limiting portion 222 are arranged between the two finger base connecting rods. The left and right sides of the limiting portion 222 extend outward to contact the limiting rod 243.

[0057] In some embodiments of the present application, referring to Figure 2 and Figure 3 The rack 240 comprises a middle connecting plate 241, four protruding end portions 242 and two limiting rods 243. The middle connecting plate 241 is a square structure, and the four protruding end portions 242 are arranged on the four corners of the middle connecting plate 241, respectively. The outer sides of the four end portions are rotatably connected to the four rocker arms 230, respectively. The optical axis 250 is movably connected to the slider 220 through the middle connecting plate 241. It should be noted that a copper graphite bearing is connected between the optical axis 250 and the middle connecting plate 241, so that the optical axis 250 can slide up and down relative to the rack 240, realizing accurate linear guidance. Further, the two limiting rods 243 are arranged on the side of the middle connecting plate 241 away from the driving mechanism 300, that is, the two limiting rods 243 are higher than the middle connecting plate 241 as shown in Figure 3 The front end and the rear end of one of the limiting rods 243 are connected to the inner sides of the two protruding end portions 242 on the left side, respectively, and the front end and the rear end of the other limiting rod 243 are connected to the inner sides of the two protruding end portions 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 portion 222 contacts the limiting rod 243, limiting the further downward movement of the optical axis 250 and the slider 220. At this time, the flexible manipulator is closed, and the two finger blocks 110 just cross, while preventing the flexible manipulator from being excessively closed, which may cause the two finger blocks 110 to collide and be damaged.

[0058] In some embodiments of the present application, two rectangular connecting frames 260 are arranged symmetrically on the left and right sides of the driving box 360 of the driving mechanism 300, as shown in Figure 2 The rectangular connecting frame 260 is vertically placed, and the upper side of the rectangular connecting frame 260 is fixedly connected to the middle connecting plate 241 of the rack 240, and the lower side of the rectangular connecting frame 260 is fixedly connected to the driving box 360. The optical axis 250 is arranged between the two rectangular connecting frames 260.

[0059] In some embodiments of the present application, the driving mechanism 300 is implemented in a self-adaptive variable transmission ratio driving mode, and the flexible finger 100 is provided with a self-adaptive adjustable linear driving force by the optical axis 250 of the manipulator transmission mechanism 200. Referring to Figure 2 The driving mechanism 300 includes a driving box 360, the upper side and the lower side of the driving box 360 are respectively connected with the manipulator transmission mechanism and the driver 370, the first lead screw 310, the second lead screw 320, the first nut 330, the second nut 340 and the constant torque pre-tightening device 350 are all arranged in the driving box 360. Specifically, the driving mechanism 300 includes a first guide rail 322, a first sliding block 323, a second sliding block 354 and a second guide rail 353, the first guide rail 322 and the second guide rail 353 are fixedly arranged in the inner side of the side wall of the driving box 360, the first sliding block 323 is slidably arranged on the first guide rail 322, the second sliding block 354 is slidably arranged on the second guide rail 353, the first sliding block 323 is fixedly connected with the second nut 340, and the second sliding block 354 is connected with the constant torque pre-tightening device 350. It should be noted that the first guide rail 322 is used to realize the first lead, and the second guide rail 353 is used to realize the second lead.

[0060] In some specific embodiments of the present application, the driving mechanism 300 further includes a nut connecting block 324, and the nut connecting block 324 is fixedly connected with the second sliding block 354 and the second nut 340 respectively. Referring to Figure 2 and Figure 4 The nut connecting block 324 includes a nut connecting vertical plate and a nut connecting horizontal plate which are perpendicular to each other, the nut connecting vertical plate is fixedly connected with the second sliding block 354, and the lower side of the nut connecting horizontal plate is fixedly connected with the second nut 340. The present application limits the rotation of the second nut 340, so that it can only move linearly along the axial direction of the second lead screw 320 and serve as the final output end of the entire driving mechanism 300. Further, the upper side of the nut connecting horizontal plate is fixedly connected with the lower side of the output end flange 321, and the upper side of the output end flange 321 is fixedly connected with the optical axis 250.

[0061] In some specific embodiments of the present application, the driving mechanism 300 further includes a pre-tightening device connecting block 355, and the pre-tightening device connecting block is fixedly connected with the second sliding block 354 and the constant torque pre-tightening device respectively. Referring to Figure 2 and Figure 5The pre-tightening device connecting block 355 comprises mutually perpendicular device connecting vertical plates and device connecting horizontal plates, the device connecting vertical plates are fixedly connected with the second sliding blocks 354, the device connecting horizontal plates are fixedly connected with the lower side of the constant moment damping turntable 351, the upper side of the constant moment damping turntable 351 is fixedly connected with the shaft end fixed flange 352, and the shaft end fixed flange 352 is sleeved on the first lead screw 310. The pre-tightening device connecting block 355 and the second sliding block 354 are matched to allow the constant torque pre-tightening device 350 to move axially and linearly along with the screw rod combination (consisting of the first lead screw 310 and the second lead screw 320), while the rotation of the constant torque pre-tightening device 350 is limited, so that the constant torque pre-tightening device 350 can provide a preset, constant and pre-tightening torque for the first lead screw 310 to resist the rotation of the first lead screw 310.

[0062] Further, the nut connecting vertical plates and the first sliding blocks 323 are both provided with two, the device connecting vertical plates, the second sliding blocks 354 and the second sliding blocks 354 are both provided with two, and the driving box 360 is a cuboid structure, the two first sliding blocks 323 are arranged on two adjacent side walls of the driving box 360, and the two second sliding blocks 354 are arranged on the other two adjacent side walls of the driving box 360.

[0063] In some specific embodiments of the present application, referring to Figure 2 and Figure 6 The driving mechanism 300 further comprises a bearing mounting base 312 and a nut bearing 313, the bearing mounting base 312 is fixedly arranged on the inner side of the side wall of the driving box 360, the nut bearing 313 is arranged between the bearing mounting base 312 and the first nut 330, the first nut 330 can move linearly relative to the driving box 360 but cannot rotate, the first nut 330 is threadedly connected with the first lead screw 310, so that the first lead screw 310 can move linearly relative to the first nut 330. Further, the upper side and the lower side of the nut bearing 313 are respectively provided with a nut stop ring 314 and a nut limiting ring 315, and the nut stop ring 314 and the nut limiting ring 315 are sleeved on the first lead screw 310. The bearing mounting base 312, the nut stop ring 314 and the nut limiting ring 315 are matched to make the first nut 330 only rotate but cannot move axially. It can be understood that the nut bearing 313 of the embodiment of the present application can adopt a deep groove ball bearing.

[0064] Herein, one specific embodiment is described.

[0065] The working principle of the flexible manipulator in the fast small force closing state is as follows: when the flexible manipulator starts to grab an object, the driver 370 rotates to make the input flange 311 rotate, so as to drive the first screw rod 310 and the first nut 330 to rotate. At this time, because the flexible manipulator is empty or is subjected to a small resistance, the reaction torque acting on the first screw rod 310 is smaller than the pre-tightening torque of the constant torque pre-tightening device 350, the first screw rod 310 is locked by the constant torque pre-tightening device 350, the rotation trend of the combined screw rod connected by the first screw rod 310 and the second screw rod 320 is inhibited by the constant torque pre-tightening device 350, the combined screw rod is kept from rotating, and the first nut 330 is kept from being inhibited from rotating. Through the first lead (such as 18 mm), the combined screw rod is driven to perform fast small force linear motion (non-rotation), and the fast small force motion is transmitted to the optical shaft 250 through the second nut 340 and the output flange 321, so that the flexible fingers 100 are quickly closed.

[0066] It should be noted that the constant torque pre-tightening device 350 is used to limit the rotation of the combined screw rod composed of the first screw rod 310 and the second screw rod 320, and does not limit the linear motion of the combined screw rod extending or retracting into the drive box 360. When the first screw rod 310 does not rotate and the first nut 330 rotates, because the first nut 330 is fixed in the drive box 360 by the bearing mounting seat and cannot move up and down but only rotates, and the first nut 330 is connected with the second nut 340 by threads, the first screw rod 310 moves linearly downward under the rotation of the first nut 330, the first screw rod 310 drives the second screw rod 320 to move linearly downward through the shaft coupling 316, the constant torque pre-tightening device moves linearly downward along the second guide rail 353, and the second nut 340 and the output flange 321 move linearly downward along the first guide rail 322, so that the optical shaft 250 moves linearly downward, driving the flexible fingers 100 to close.

[0067] The working principle of the flexible manipulator in the slow large force grabbing state is as follows: when the flexible fingers 100 contact an object and start to exert a gripping force, the external load of the flexible manipulator increases, which is reacted on the combined screw rod through the transmission mechanism, generating a reaction torque. When the reaction torque reaches or exceeds the pre-tightening torque threshold set by the constant torque pre-tightening device 350, the constant force torque damping disc starts to slip, and the rotation of the first screw rod 310 is invalid. At this time, the rotation of the first nut 330 drives the first screw rod 310 and the second screw rod 320 to rotate together through the thread engagement. Because the rotation of the second nut 340 is limited by the first guide rail 322 and the second guide rail 353, the rotation of the combined screw rod drives the second nut 340 to perform slow but significantly amplified linear motion through the second lead (such as 1 mm). The slow small force motion is transmitted to the optical shaft 250 through the output flange 321, so that the flexible fingers 100 can perform stable large force gripping.

[0068] Specifically, when the constant torque pre-tightening device 350 cannot inhibit the rotation of the first screw rod 310, the first nut 330 can drive the first screw rod 310 and the second screw rod 320 to rotate together due to the threaded connection between the first nut 330 and the first screw rod 310. Meanwhile, the second nut 340 connected to the first guide rail 322 cannot rotate but can only move linearly, and the second nut 340 moves along the first guide rail 322 downward under the rotation of the second screw rod 320 due to the threaded connection between the second screw rod 320 and the second nut 340, which makes the constant torque pre-tightening module move downward along the second guide rail 353 and makes the output flange 321 and the optical axis 250 move downward, thereby driving the flexible fingers 100 to close.

[0069] The present application realizes the self-adaptive adjustment of the gripping force of the flexible manipulator by improving the mechanical design of the driving mechanism 300 and cooperating with the constant torque pre-tightening device, and automatically optimizes the force-speed output characteristics under different working conditions.

[0070] The above description is only a preferred embodiment of the present application, and the present application is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure. The technical solutions and / or embodiments within the protection scope of the present application can have various modifications and changes.

Claims

1. A flexible manipulator, characterized by, The invention relates to a flexible finger (100) for grabbing objects and a mechanical hand transmission mechanism (200) for driving the flexible finger (100) to open and close to grab objects, and a driving mechanism (300) for providing a first lead and a second lead of a grabbing linear driving force and allowing adaptive variable transmission ratio, the mechanical hand transmission mechanism (200) being connected with the flexible finger (100) and the driving mechanism (300) respectively. The driving mechanism (300) comprises a driving box (360), a first screw rod (310), a second screw rod (320), a first nut (330), a second nut (340) and a constant torque pre-tightening device (350), the first screw rod (310) is fixedly connected with the second screw rod (320), the first screw rod (310) is threadedly connected with the first nut (330), the first nut (330) is fixedly connected with an input end flange (311), the input end flange (311) is fixedly connected with an output shaft (371) of a driver (370), the second screw rod (320) is threadedly connected with the second nut (340), the second nut (340) is fixedly connected with the mechanical hand transmission mechanism (200), the constant torque pre-tightening device (350) is slidably connected with the driving box (360) to allow linear movement of the constant torque pre-tightening device (350) and limit its rotation. The constant torque pre-tightening device (350) provides a preset constant pre-tightening torque for limiting the rotation of the first screw rod (310), the first nut (330) is rotatably connected with the driving box (360) to allow the rotation of the first nut (330) and limit its linear movement, thereby allowing the generation of the grabbing driving force of the flexible finger (100) based on the first lead. The second nut (340) is slidably connected with the driving box (360) to allow linear movement of the second nut (340) and limit its rotation, thereby allowing the generation of the grabbing driving force of the flexible finger (100) based on the second lead. The constant torque pre-tightening device (350) comprises a constant torque damping turntable (351) connected with the first screw rod (310) through an axle end fixed flange (352).

2. The flexible manipulator of claim 1, wherein, The driving mechanism (300) further comprises a first guide rail (322) and a first sliding block (323) matched with the first lead, and a second guide rail (353) and a second sliding block (354) matched with the second lead, the first guide rail (322) and the second guide rail (353) are fixedly arranged inside the side wall of the driving box (360), the first sliding block (323) is movably arranged in the first guide rail (322), the second sliding block (354) is movably arranged in the second guide rail (353), the first sliding block (323) is fixedly connected with the second nut (340), and the second sliding block (354) is fixedly connected with the constant torque pre-tightening device (350).

3. The flexible manipulator of claim 1, wherein, ​ 4. The flexible manipulator of claim 3, wherein, The driving mechanism (300) further comprises a nut connecting block (324) and a pre-tightening device connecting block (355), the nut connecting block (324) is fixedly connected with the second sliding block (354) and the second nut (340) respectively; the pre-tightening device connecting block (355) is fixedly connected with the second sliding block (354) and the fixed-torque pre-tightening device (350) respectively.

5. The flexible manipulator of claim 3, wherein, The mechanical hand transmission mechanism (200) comprises a finger base connecting rod (210), a sliding block (220), a rocker (230) and a rack (240), the finger base connecting rod (210) is fixedly connected with the flexible finger (100), the inner side of the finger base connecting rod (210) is rotatably connected with the sliding block (220), the outer side of the finger base connecting rod (210) is rotatably connected with the upper side of the rocker (230), and the lower side of the rocker (230) is rotatably connected with the rack (240).

6. The flexible manipulator of claim 5, wherein, The mechanical hand transmission mechanism (200) further comprises an optical axis (250) and a rectangular connecting frame (260), the upper side of the optical axis (250) is fixedly connected with the sliding block (220), and the two sides of the rectangular connecting frame (260) are fixedly connected with the rack (240) and the driving box (360) respectively. The sliding block (220) comprises a connecting part (221) and a limiting part (222), the connecting part (221) is fixedly connected with the limiting part (222), the connecting part (221) is rotatably connected with the finger base connecting rod (210), and the limiting part (222) is fixedly connected with the optical axis (250); the rack (240) is provided with a limiting rod (243) allowing contact with the limiting part (222) to limit the closing of the flexible finger (100).

7. The flexible manipulator of claim 3, wherein, The driving mechanism (300) further comprises a bearing mounting base (312), a nut bearing (313), a nut stop ring (314) and a nut limiting ring (315), the bearing mounting base (312) is fixedly connected with the driving box (360), the nut bearing (313) is arranged between the bearing mounting base (312) and the first nut (330), and the nut stop ring (314) and the nut limiting ring (315) are arranged on the two sides of the nut bearing (313) respectively.

8. The flexible manipulator of claim 6, wherein, The second lead screw (320) is fixedly connected with an output end flange (321) at one end away from the first lead screw (310), the output end flange (321) is fixedly connected with the optical axis (250); the first lead screw (310) is fixedly connected with an input end flange (311) at one end away from the second lead screw (320), and the input end flange (311) is fixedly connected with an output shaft (371) of a driver (370).

9. The flexible manipulator of claim 1, wherein, The flexible finger (100) comprises double-finger tip blocks (111) and single-finger tip blocks (112) allowing partial intersection to form a closed gripping space.

10. A method of operating a flexible manipulator having adaptive gripping capability, characterized by, The method applied to the flexible mechanical hand with adaptive gripping force according to any one of claims 1 to 9 comprises the following steps: When the reaction torque of the flexible manipulator under the grabbing load is lower than a preset torque threshold, the first nut (330) is rotated by the driver (370), and the first screw rod (310) and the second screw rod (320) are linearly moved with a first lead in a state that the first screw rod (310) is limited from rotating by the torque pre-tightening device (350); When the reaction torque of the flexible manipulator under the grabbing load reaches or exceeds the preset torque threshold, the first nut (330) is rotated and drives the first screw rod (310) and the second screw rod (320) to rotate through thread engagement, and the second nut (340) is linearly moved with a second lead in a state that the second nut (340) is limited from rotating.

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