A bionic grasping device for attachment to different wall surfaces

Abstract

The present invention discloses a bionic grasping device for attaching to different wall surfaces, which includes a mounting frame, and split-foot mechanisms are respectively arranged on the left and right sides of the mounting frame; each split-foot mechanism includes a split foot and a four-bar mechanism, and the split-foot frame of the split foot is connected to the mounting frame through the four-bar mechanism. A bionic grasping component and a bionic adhesion component are installed on the split-foot frame. The bionic adhesion component is fixedly arranged at the bottom of the split-foot frame and protrudes downward from the split-foot frame. The bionic grasping component includes a plurality of hook claw pieces that are arranged in sequence and overlapped in the front-back direction and are independent of each other. Hook spines are provided at the bottom of the hook claw pieces. A lifting component is arranged on the split-foot frame. In the natural state, the hook spines of the hook claw pieces protrude downward from the bottom of the bionic adhesion component; through the action of the lifting component, the hook spines on each hook claw piece are driven to lift upward above the bottom of the bionic adhesion component. The advantages of the present invention: It realizes effective attachment to rough wall surfaces and smooth wall surfaces and can be conveniently switched between the two.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and particularly to a bionic grasping device for attaching to different wall surfaces. Background Art

[0002] In recent years, the stable crawling of robots on various wall surfaces has become one of the key research points in the field of wall-climbing robots. At present, for a single type of wall surface (rough or smooth wall surface), researchers around the world have developed a variety of bionic wall-climbing robots. However, most of the existing wall-climbing robots can only climb on a single type of wall surface, cannot achieve the collaborative application of multiple attachment methods, and fail to well solve the problems of stability and adaptability when moving on different wall surfaces. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a bionic grasping device for attaching to different wall surfaces, so as to achieve effective attachment on both rough wall surfaces and smooth wall surfaces and convenient switching between the two.

[0004] The present invention is achieved by the following technical solutions:

[0005] A bionic grasping device for attaching to different wall surfaces includes a mounting frame, and split-foot mechanisms are respectively arranged on the left and right sides of the mounting frame;

[0006] Each split-foot mechanism includes a split foot and a four-bar mechanism. The split foot includes a split-foot frame, and the split-foot frame is connected to the mounting frame through the four-bar mechanism. A bionic grasping component and a bionic adhesion component are mounted on the split-foot frame. The bionic adhesion component is fixedly arranged at the bottom of the split-foot frame and protrudes downward from the split-foot frame. The bionic grasping component includes a plurality of hook claw pieces that are arranged in an overlapping manner in the front-rear direction and are independent of each other. A hook thorn with an inward inclination at the bottom is provided at a position near the outer end of the bottom of the hook claw piece. A lifting component is arranged on the split-foot frame. In the natural state, the hook thorn of the hook claw piece protrudes downward from the bottom of the bionic adhesion component; through the action of the lifting component, each hook claw piece can be driven to move upward, so as to drive the hook thorns on each hook claw piece to lift upward above the bottom of the bionic adhesion component.

[0007] Furthermore, there are two front and rear side plates respectively provided on the front and rear sides of the split footrest. Each side plate is provided with an installation hole and a kidney-shaped hole. A fixing hole and a limiting groove are provided on the hook claw piece. A fixing shaft passes through the fixing holes on multiple hook claw pieces from front to back in sequence, and the front and rear ends of the fixing shaft respectively pass through the installation holes on the two side plates, so as to realize the rotational installation of multiple hook claw pieces on the split footrest; A limiting shaft passes through the limiting grooves on multiple hook claw pieces from front to back in sequence, and the front and rear ends of the limiting shaft respectively pass through the kidney-shaped holes on the two side plates, so as to realize the limitation of multiple hook claw pieces; The lifting component is a shape memory spring. Shape memory springs are respectively provided on the outer sides of the two side plates. The upper end of the shape memory spring is fixed on the side plate, and the lower end of the shape memory spring is fixed to the limiting shaft. By energizing and contracting the shape memory spring, the limiting shaft is driven to move upward along the kidney-shaped hole, and then multiple hook claw pieces are driven to turn upward around the fixing shaft, so as to lift the barbs on the hook claw piece.

[0008] Furthermore, the bionic adhesion assembly includes an adhesion airbag and an airbag fixing plate fixed to the upper end of the adhesion airbag. The airbag fixing plate is fixed on the split footrest. A layer of adhesion material layer is provided on the surface of the adhesion airbag. Particulates are filled in the air cavity inside the adhesion airbag. An air nozzle communicated with the air cavity is provided on one side of the adhesion airbag.

[0009] Furthermore, the hook claw piece includes a rigid main body and a flexible component cast in the recessed part on the surface of the rigid main body. A cantilever extending outward is provided at the top end of the rigid main body. An auxiliary connection block is provided at the outer end of the cantilever. The cantilever is made of flexible material, and the auxiliary connection block is a rigid component. An auxiliary hole is provided on the auxiliary connection block. An auxiliary shaft passes through the auxiliary holes on multiple hook claw pieces from front to back in sequence, and the front and rear ends of the auxiliary shaft respectively pass through the auxiliary installation holes on the two side plates, so as to realize the auxiliary installation of the hook claw piece and the split footrest.

[0010] Furthermore, a driving mechanism is provided on the mounting rack. By driving the four-bar mechanisms of the two split foot mechanisms to move synchronously through the driving mechanism, the two split feet are driven to move synchronously, and then the grasping or releasing actions of the two split feet are realized.

[0011] Furthermore, the four-bar mechanism includes a fixed rod, a first connecting rod, a connecting rod, and a second connecting rod that are sequentially hinged end to end. The fixed rod is fixedly connected to the mounting rack or directly constitutes a part of the mounting rack. One end of the first connecting rod and one end of the second connecting rod are respectively hinged to both ends of the fixed rod. The other end of the first connecting rod and the other end of the second connecting rod are respectively hinged to both ends of the connecting rod. An extension part extending outward is provided at the end of the connecting rod far from the mounting rack. The split footrest of the split foot is mounted on the extension part.

[0012] Furthermore, the driving mechanism includes a driver, a driving gear, a driven gear, a first working gear, and a second working gear. The driving gear is fixedly connected to the output shaft of the driver. The driving gear and the driven gear are both bevel gears and are meshed with each other. The first working gear is coaxially fixedly connected to the driven gear. The first working gear is meshed with the second working gear. The gear shafts of the two working gears are respectively fixedly connected to the first connecting rods of the two sub-foot mechanisms.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The present invention provides a bionic grasping device for attachment to different wall surfaces, which integrates a bionic grasping component and a bionic adhesion component, and can achieve effective attachment on both rough and smooth wall surfaces, that is, effective attachment on both wall surfaces.

[0015] 2. The present invention provides a bionic grasping device for attachment to different wall surfaces. By adopting a shape memory spring as a pulling component, the expansion and contraction deformation of the shape memory spring when powered on and off is utilized to realize whether the bionic grasping component is lifted or not, thereby controlling whether the bionic adhesion component is exposed or not, thereby realizing automatic and rapid switching between rough wall attachment and smooth wall attachment.

[0016] 3. The present invention provides a bionic grasping device for attachment to different wall surfaces. Its bionic grasping component uses two left and right separate foot mechanisms to form a stable grasping with the rough wall in the form of a grasping action, which can achieve stable grasping and detaching on vertical walls, inclined walls, and even ceilings.

[0017] 4. The present invention provides a bionic grasping device for attachment to different wall surfaces. Its bionic adhesion component uses an adhesion airbag with a layer of adhesion material on the surface, which is combined with particulate matter filled in the air cavity inside the adhesion airbag. By controlling the air pressure in the air cavity inside the adhesion airbag, effective attachment or detachment on the smooth wall can be achieved.

[0018] 5. The present invention provides a bionic grasping device for attachment to different wall surfaces. It uses the same drive mechanism to drive the two separate leg mechanisms to move synchronously, which increases the consistency of the two separate leg movements. At the same time, only one drive mechanism is required, which saves energy and reduces weight. By controlling the intermittent forward and reverse rotation of the drive, the compact connection between the grasping and detaching actions can be achieved, thereby ensuring the continuity of the entire climbing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is an overall three-dimensional diagram of the present invention.

[0020] Figure 2 It is a three-dimensional diagram of a single split foot mechanism of the present invention.

[0021] Figure 3 It is the front view of the multi - foot mechanism when the bionic grasping component of the present invention functions.

[0022] Figure 4 It is the front view of the multi - foot mechanism when the bionic adhesion component of the present invention functions.

[0023] Figure 5 It is the front view of the hook claw piece of the present invention.

[0024] Figure 6 It is the perspective view of the bionic adhesion component of the present invention.

[0025] Figure 7 It is the perspective view of the driving mechanism of the present invention.

[0026] Reference numerals in the figure: 1 mounting bracket; 2 multi - foot mechanism; 3 multi - foot frame; 4 first connecting rod; 5 connecting rod; 6 second connecting rod; 7 extension part; 8 hook claw piece; 9 hook thorn; 10 fixing hole; 11 limiting groove; 12 fixing shaft; 13 kidney - shaped hole; 14 limiting shaft; 15 shape - memory spring; 16 rigid body; 17 flexible component; 18 cantilever; 19 auxiliary connecting block; 20 auxiliary hole; 21 driver; 22 driving gear; 23 driven gear; 24 first working gear; 25 second working gear; 26 adhesion airbag; 27 airbag fixing plate; 28 air nozzle. Detailed implementation manners

[0027] The embodiments of the present invention will be described in detail below. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0028] Refer to Figures 1 to 7 , this embodiment discloses a bionic grasping device for attaching to different wall surfaces, including a mounting bracket 1, and multi - foot mechanisms 2 are respectively arranged on the left and right sides of the mounting bracket 1.

[0029] Each sub-foot mechanism 2 includes a sub-foot and a four-bar mechanism. The sub-foot includes a sub-foot frame 3, and the sub-foot frame 3 is connected to the mounting frame 1 through the four-bar mechanism. The four-bar mechanism includes a fixed rod, a first connecting rod 4, a connecting rod 5, and a second connecting rod 6 that are sequentially hinged end to end. The fixed rod is fixedly connected to the mounting frame 1 or directly constitutes a part of the mounting frame 1. In this embodiment, the fixed rod constitutes a part of the mounting frame 1. One end of the first connecting rod 4 and one end of the second connecting rod 6 are respectively hinged to both ends of the fixed rod. The other end of the first connecting rod 4 and the other end of the second connecting rod 6 are respectively hinged to both ends of the connecting rod 5. An extension 7 extending outward is provided at the end of the connecting rod 5 far from the mounting frame 1, and the sub-foot frame 3 of the sub-foot is fixedly installed on the extension 7. A bionic grasping component and a bionic adhesion component are installed on the sub-foot frame 3. The bionic adhesion component is fixedly arranged at the bottom of the sub-foot frame 3 and protrudes downward from the sub-foot frame 3. The bionic grasping component includes a plurality of hook claw pieces 8 that are sequentially overlapped and arranged in the front-rear direction and are independent of each other. A hook thorn 9 with an inwardly inclined bottom is provided at a position near the outer end of the bottom of the hook claw piece 8. A lifting component is provided on the sub-foot frame 3. In the natural state, the hook thorn 9 of the hook claw piece 8 protrudes downward from the bottom of the bionic adhesion component; by the action of the lifting component, each hook claw piece 8 can be driven to move upward, so as to drive the hook thorn 9 on each hook claw piece 8 to lift above the bottom of the bionic adhesion component.

[0030] The sub-foot frame 3 is integrally in a U-shaped frame structure. The sub-foot frame 3 includes a back plate and side plates located on both the front and rear sides of the back plate. A plurality of hook claw pieces 8 are located in the space surrounded by the back plate and the two side plates. An installation hole and a kidney-shaped hole 13 are opened on each side plate. A fixing hole 10 and a limiting groove 11 are opened on the hook claw piece 8. By passing a fixing shaft 12 through the fixing holes 10 on a plurality of hook claw pieces 8 from front to back in sequence, and respectively passing the front and rear ends of the fixing shaft 12 through the installation holes on the two side plates, the rotational installation of a plurality of hook claw pieces 8 on the sub-foot frame 3 is realized; by passing a limiting shaft 14 through the limiting grooves 11 on a plurality of hook claw pieces 8 from front to back in sequence, and respectively passing the front and rear ends of the limiting shaft 14 through the kidney-shaped holes 13 on the two side plates, the limitation of a plurality of hook claw pieces 8 is realized; the lifting component is a shape memory spring 15. Shape memory springs 15 are respectively provided on the outer sides of the two side plates. The upper end of the shape memory spring 15 is fixed on the side plate, and the lower end of the shape memory spring 15 is fixed to the limiting shaft 14. By the energized contraction of the shape memory spring 15, the limiting shaft 14 is driven to move upward along the kidney-shaped hole 13, and then a plurality of hook claw pieces 8 are driven to turn upward around the fixing shaft 12, realizing the lifting of the hook thorn 9 on the hook claw piece 8.

[0031] The hook claw piece 8 includes a rigid body 16 and a flexible component 17 cast in a recessed portion on the surface of the rigid body 16. At the top of the rigid body 16, there is a cantilever 18 extending outward. At the outer end of the cantilever 18, there is an auxiliary connection block 19. The cantilever 18 is made of a flexible material, and the auxiliary connection block 19 is a rigid component. An auxiliary hole 20 is formed in the auxiliary connection block 19. An auxiliary shaft passes through the auxiliary holes 20 on multiple hook claw pieces 8 from front to back in sequence, and the front and rear ends of the auxiliary shaft respectively pass through the auxiliary mounting holes on two side plates, so as to realize the auxiliary installation of the hook claw piece 8 and the split foot frame 3. Here, the auxiliary connection block 19 is connected to the rigid body 16 through the flexible cantilever 18. The flexible cantilever 18 has a certain elasticity. When the hook claw piece 8 rotates around the fixed shaft 12, the flexible cantilever 18 can undergo elastic deformation, without hindering the rotation action of the hook claw piece 8, ensuring the normal rotation of the hook claw piece 8.

[0032] A driving mechanism is provided on the mounting frame 1. The four-bar mechanisms of the two split foot mechanisms 2 are driven to move synchronously through the driving mechanism, so as to drive the two split feet to move synchronously, and further realize the grasping or releasing actions of the two split feet. The driving mechanism includes a driver 21, a driving gear 22, a driven gear 23, a first working gear 24, and a second working gear 25. The driving gear 22 is fixedly connected to the output shaft of the driver 21. The driving gear 22 and the driven gear 23 are both bevel gears and mesh with each other. The first working gear 24 is fixedly connected to the driven gear 23 coaxially. The first working gear 24 meshes with the second working gear 25. The gear shafts of the two working gears are respectively fixedly connected to the first connecting rods 4 of the two split foot mechanisms 2. The driver 21 can be any one of a servo motor, a DC motor, or a stepping motor. The driver 21 drives the driving gear 22 to rotate. The driving gear 22 drives the driven gear 23 meshing with it to rotate. The driven gear 23 drives the first working gear 24 to rotate synchronously. The first working gear 24 then drives the second working gear 25 meshing with it to rotate. The two working gears respectively drive the two four-bar mechanisms to move synchronously, and further drive the left and right split feet to move synchronously, and further realize the grasping and releasing actions of the two split feet with the wall surface.

[0033] The bionic adhesion assembly includes an adhesion airbag 26 and an airbag fixing plate 27 fixed to the upper end of the adhesion airbag 26. The airbag fixing plate 27 is fixed on the two side plates of the split foot frame 3. A layer of adhesion material layer is provided on the surface of the adhesion airbag 26. The inner cavity of the adhesion airbag 26 is filled with particulate matter. A nozzle 28 communicating with the air cavity is provided on one side of the adhesion airbag 26. The adhesion airbag 26 is evacuated or inflated through the nozzle 28. Among them, the adhesion material layer can be made of polydimethylsiloxane material, and the particulate matter can be quartz sand particles. The adsorption and desorption principle of the bionic adhesion assembly is:

[0034] In the initial state, the pressure difference between the inside and outside of the adhesion airbag 26 is nearly zero. The particulate matter inside the adhesion airbag 26 is in a scattered arrangement and accumulation state. The overall stiffness of the adhesion airbag 26 is small, and it has good surface adaptability. At this time, an external pressing force is applied to make the surface of the adhesion airbag 26 fully contact the wall surface adaptively. Subsequently, the adhesion airbag 26 is evacuated to reduce the air pressure in the internal air chamber of the adhesion airbag 26, so that the particulate matter inside the adhesion airbag 26 shows a compact state in terms of volume while the number and physical properties remain unchanged. At this time, the overall elastic modulus and stiffness of the adhesion airbag 26 increase, that is, the particulate matter blocking effect occurs. The adhesion airbag 26 effectively adheres to the wall surface through the adhesion material layer on the surface. By maintaining a certain air pressure, the adhesion state can be maintained. When desorption is required, the adhesion airbag 26 is inflated until its air pressure is equal to the external atmospheric pressure. At this time, the particulate matter inside the adhesion airbag 26 returns to the initial state, and the adhesion airbag 26 desorbs from the wall surface through the adhesion material layer on the surface. That is, by controlling the air pressure in the internal air chamber of the adhesion airbag 26, effective attachment or desorption on a smooth wall surface can be achieved.

[0035] The working process of the bionic grasping device provided in this embodiment is as follows:

[0036] When the wall surface is a rough wall surface, the shape memory spring 15 is not energized. At this time, the shape memory spring 15 is in a stretched state, the limit shaft 14 is located at the bottom end of the kidney-shaped hole 13, and the barbs 9 of the hook claw piece 8 protrude downward from the bottom of the bionic adhesion component. At this time, the bionic grasping component plays a role. When grasping, the drive mechanism drives the two four-bar mechanisms to act, driving the two groups of sub-feet to act simultaneously. Driven by the lead screw mechanism, the movement trajectory of each group of sub-feet is in a D shape. The sub-feet slowly fall from the high point, and the hook claw piece 8 array contacts the rough wall surface at a certain angle and drags a certain distance on the wall surface. When the barbs 9 of each hook claw piece 8 are successfully locked with the protrusions on the wall surface, a grasping is completed. At this time, the two sub-feet form a stable grasp with the wall surface in a pair-grabbing form. When desorbing, the driver 21 rotates in the reverse direction by the same angle, and the sub-foot mechanism 2 desorbs from the wall surface at a certain angle and moves to the highest point, waiting for the next grasping action. In this way, a successful grasping and desorbing action is completed.

[0037] When the wall surface is a smooth wall surface, the shape memory spring 15 is energized and contracts, driving the limit shaft 14 to move upward along the kidney-shaped hole 13. The limit shaft 14 then drives the multiple hook claw pieces 8 to flip upward around the fixed shaft 12, thereby lifting the barbs 9 on the hook claw pieces 8, so that the barbs 9 on each hook claw piece 8 are lifted above the bottom of the bionic adhesion component, and then the bionic adhesion component can be switched to play a role. At this time, the adhesion airbag 26 contacts the wall surface. By controlling the air pressure in the internal air chamber of the adhesion airbag 26, effective attachment or desorption on a smooth wall surface can be achieved.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A bionic grasping device for attachment to different wall surfaces, comprising a mounting frame (1), characterized in that: On the left and right sides of the mounting bracket (1), there are respectively provided with split-foot mechanisms (2); Each split-foot mechanism (2) includes a split foot and a four-bar mechanism. The split foot includes a split-foot frame (3). The split-foot frame (3) is connected to the mounting bracket (1) through the four-bar mechanism. A bionic grasping component and a bionic adhesion component are installed on the split-foot frame (3). The bionic adhesion component is fixedly arranged at the bottom of the split-foot frame (3) and protrudes downward from the split-foot frame (3). The bionic grasping component includes a plurality of hook claw pieces (8) that are arranged in an overlapping manner in the front-back direction and are independent of each other. At the position near the outer end of the bottom of the hook claw piece (8), there is a hook thorn (9) with an inward inclination at the bottom. A lifting component is provided on the split-foot frame (3). In the natural state, the hook thorn (9) of the hook claw piece (8) protrudes downward from the bottom of the bionic adhesion component; through the action of the lifting component, each hook claw piece (8) can be driven to move upward, so as to drive the hook thorns (9) on each hook claw piece (8) to lift above the bottom of the bionic adhesion component; On the front and back sides of the split-foot frame (3), there are respectively provided with two front and back side plates. An installation hole and a kidney-shaped hole (13) are opened on each side plate. A fixing hole (10) and a limiting groove (11) are opened on the hook claw piece (8). Through a fixing shaft (12) passing through the fixing holes (10) on a plurality of hook claw pieces (8) from front to back in sequence, and respectively passing the front and rear ends of the fixing shaft (12) through the installation holes on the two side plates, the rotational installation of the plurality of hook claw pieces (8) on the split-foot frame (3) is realized; through a limiting shaft (14) passing through the limiting grooves (11) on a plurality of hook claw pieces (8) from front to back in sequence, and respectively passing the front and rear ends of the limiting shaft (14) through the kidney-shaped holes (13) on the two side plates, the limiting of the plurality of hook claw pieces (8) is realized; the lifting component is a shape memory spring (15). Shape memory springs (15) are respectively provided on the outer sides of the two side plates. The upper end of the shape memory spring (15) is fixed on the side plate, and the lower end of the shape memory spring (15) is fixed to the limiting shaft (14). Through the electrified contraction of the shape memory spring (15), the limiting shaft (14) is driven to move upward along the kidney-shaped hole (13), and further drive a plurality of hook claw pieces (8) to flip upward around the fixing shaft (12), so as to realize the lifting of the hook thorns (9) on the hook claw pieces (8); The bionic adhesion component includes an adhesion airbag (26) and an airbag fixing plate (27) fixed to the upper end of the adhesion airbag (26). The airbag fixing plate (27) is fixed on the split-foot frame (3). The surface of the adhesion airbag (26) is provided with an adhesion material layer. The internal air cavity of the adhesion airbag (26) is filled with particulate matter. One side of the adhesion airbag (26) is provided with a nozzle (28) communicated with the air cavity.

2. The bionic grasping device for attachment to different wall surfaces according to claim 1, wherein: The hook claw piece (8) includes a rigid body (16) and a flexible component (17) formed by casting in a recessed part on the surface of the rigid body (16). At the top of the rigid body (16), there is a cantilever (18) extending outward. At the outer end of the cantilever (18), there is an auxiliary connection block (19). The cantilever (18) is made of a flexible material, and the auxiliary connection block (19) is a rigid component. An auxiliary hole (20) is formed in the auxiliary connection block (19). An auxiliary shaft passes through the auxiliary holes (20) of multiple hook claw pieces (8) from front to back in sequence, and the front and rear ends of the auxiliary shaft respectively pass through the auxiliary mounting holes on two side plates, so as to realize the auxiliary installation of the hook claw piece (8) and the split foot frame (3).

3. The bionic grasping device for attachment to different wall surfaces according to claim 1, wherein: A driving mechanism is provided on the mounting frame (1). The four-bar mechanisms of the two split foot mechanisms (2) are driven by the driving mechanism to move synchronously, so as to drive the two split feet to move synchronously, and further realize the grasping or detaching actions of the two split feet.

4. The bionic grasping device for attaching to different wall surfaces according to claim 3, wherein: The four-bar mechanism includes a fixed rod, a first connecting rod (4), a connecting rod (5), and a second connecting rod (6) that are sequentially hinged end to end. The fixed rod is fixedly connected to the mounting frame (1) or directly constitutes a part of the mounting frame (1). One end of the first connecting rod (4) and one end of the second connecting rod (6) are respectively hinged to both ends of the fixed rod. The other end of the first connecting rod (4) and the other end of the second connecting rod (6) are respectively hinged to both ends of the connecting rod (5). An extension (7) extending outward is provided at the end of the connecting rod (5) far from the mounting frame (1). The split foot frame (3) of the split foot is mounted on the extension (7).

5. The bionic grasping device for attachment to different wall surfaces according to claim 4, wherein: The driving mechanism includes a driver (21), a driving gear (22), a driven gear (23), a first working gear (24), and a second working gear (25). The driving gear (22) is fixedly connected to the output shaft of the driver (21). The driving gear (22) and the driven gear (23) are both bevel gears and mesh with each other. The first working gear (24) is fixedly connected coaxially with the driven gear (23). The first working gear (24) meshes with the second working gear (25). The gear shafts of the two working gears are respectively fixedly connected to the first connecting rods (4) of the two split foot mechanisms (2).

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