A rope-driven pneumatic omni-directional variable stiffness gripper

Abstract

The application discloses a rope-driven pneumatic omnidirectional variable-rigidity clamping jaw, which comprises a rack, soft bionic fingers arranged on the rack, a rope driving mechanism and an air pump. The soft bionic fingers are provided with air cavities and particle air cavities. The air cavities and the particle air cavities are arranged along the axial direction of the soft bionic fingers. The particle air cavities are arranged on the outer side of the air cavities in the circumferential direction. In the axial direction of the soft bionic fingers, the particle air cavities are alternately provided with storage cavities and flexible joint cavities which are in air communication with each other, and at least one storage cavity is filled with particles. The rope driving mechanism is used for adjusting the swing direction of the soft bionic fingers. The air pump is used for inflating and exhausting the air cavities and the particle air cavities. At this time, the flexible joint cavities are equivalent to the bending positions of the human finger joints. Under the change of air pressure, the deformation of the flexible joint cavities is not affected by the particle blockage in the deformation process of the soft bionic fingers, and the flexible joint cavities can be more smoothly contracted and recovered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of clamping jaws, and particularly relates to a rope-driven pneumatic omnidirectional variable stiffness clamping jaw. BACKGROUND

[0002] Nowadays, soft actuators have made remarkable achievements in the development of technology and application, and the driving modes of the actuators are gradually diversified, such as rope driving, pneumatic driving, shape memory alloy driving and magnetic fluid driving. Among them, pneumatic driving has become one of the main directions of soft actuator research due to its excellent compliance and relatively simple and stable structure.

[0003] In recent years, with the continuous deepening of pneumatic driving research, it is found that the variable stiffness of the pneumatic driving soft actuator can be realized by the way of particle blocking, which greatly improves the shortcomings of the insufficient stiffness of the pneumatic driving soft actuator. However, the flexibility of the pneumatic driving soft actuator is not good because the bending direction needs to be controlled by the tensile strain limiting layer. In addition, the particle blocking sometimes also has an impact on the bending effect of the soft actuator. Combining bionic technology may solve such problems, for example, the concave structure of the skin at the joints of the human fingers can ensure that the skin does not hinder the bending of the fingers during joint movement.

[0004] Relatively speaking, the rope-driven soft actuator has high control precision, flexible bending, stable control and stronger carrying capacity. At present, the research on the combination of the two is still in the initial stage, and the development of the pneumatic driving compliant object surface characteristics and the combination of particles to realize variable stiffness are relatively less. The research and solutions for the problem of particle blocking affecting bending are also less.

[0005] Further, in the process of particle gas cavity air compression and inflation recovery, because the position of the particles in the chamber space cannot be determined, the effect of particle blocking may have a negative impact on the bending and recovery of the entire soft actuator, for example, it may cause insufficient bending, so that the entire clamping jaw cannot fully fit the object surface, or when recovering, all particles are compressed to a relatively dense part, due to the mutual friction of the particles, the particles cannot be fully recovered, and the particle filling is full in the entire particle gas cavity.

[0006] Therefore, how to solve the above-mentioned influence has become a problem to be solved by those skilled in the art. SUMMARY

[0007] The purpose of the present application is to provide a rope-driven pneumatic omnidirectional variable stiffness clamping jaw to solve the negative impact of the existing particle blocking effect on the bending and recovery of the entire soft actuator.

[0008] In order to solve the above technical problems, the application provides a rope-driven pneumatic omnidirectional variable stiffness gripper, which comprises a rack, soft bionic fingers arranged on the rack, a rope driving mechanism and an air pump; the soft bionic fingers are provided with an air cavity and a granular gas cavity; the air cavity and the granular gas cavity are arranged along the axial direction of the soft bionic fingers; the granular gas cavity is surrounded by the lateral side of the air cavity; in the axial direction of the soft bionic fingers, the granular gas cavity is alternately provided with storage cavities and flexible joint cavities which are in air communication with each other, and at least one of the storage cavities is filled with granular matter; the rope driving mechanism is used for adjusting the swing direction of the soft bionic fingers; and the air pump is used for inflating and deflating the air cavity and the granular gas cavity.

[0009] In one of the embodiments, a plurality of the soft bionic fingers are arranged on the rack in the form of a ring array.

[0010] In one of the embodiments, the granular matter is spherical.

[0011] In one of the embodiments, the soft bionic finger comprises a plurality of strip-shaped soft finger walls, the inside of each of the strip-shaped soft finger walls is provided with a plurality of the storage cavities and a plurality of the flexible joint cavities, the outer surface of each of the strip-shaped soft finger walls is provided with a concave arc outer cavity wall, and a plurality of the concave arc outer cavity walls are spliced to form the air cavity.

[0012] In one of the embodiments, at the positions corresponding to the flexible joint cavities, the outer surface of the strip-shaped soft finger wall is provided with an inner concave joint position, and adjacent inner concave joint positions are annularly surrounded.

[0013] In one of the embodiments, the surface of the strip-shaped soft finger wall where adjacent strip-shaped soft finger walls are attached is provided with a wire receiving groove, the wire receiving groove is arranged along the axial direction of the strip-shaped soft finger wall, the driving rope of the rope driving mechanism passes through the wire receiving groove, and the tip part of the soft bionic finger is connected and fixed.

[0014] In one of the embodiments, the flexible joint cavities are surrounded by the outer walls of the granular gas cavities through the air permeable membranes between the two sides of the flexible joint cavities and the adjacent storage cavities.

[0015] In one of the embodiments, the cross section of the flexible joint cavity is triangular.

[0016] In one of the embodiments, the inner concave joint position is arranged in the region where the two air permeable membranes are separated from each other.

[0017] In one of the embodiments, the first air inflation and deflation interface of the air cavity and the second air inflation and deflation interface of the granular gas cavity are arranged on the rack.

[0018] The beneficial effects of the present application are as follows:

[0019] Due to the fact that the particle gas cavities are alternately provided with storage cavities and flexible joint cavities which are connected with each other in gas paths, and at least one of the storage cavities is filled with particles, while the flexible joint cavities are not filled with particles but air can pass through normally, the flexible joint cavities are equivalent to the bending part of human finger joints, and the bending is realized through the cavity structure. Under the change of air pressure, the deformation of the flexible joint cavities is not affected by the particles during the deformation of the soft bionic finger, and the flexible joint cavities can be more smoothly contracted and recovered. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0021] Figure 1 is a structural schematic diagram provided by the embodiment of the present application;

[0022] Figure 2 is Figure 1 a structural schematic diagram of the soft bionic finger;

[0023] Figure 3 is Figure 2 a structural schematic diagram of the strip-shaped soft finger wall;

[0024] Figure 4 is Figure 3 a sectional view structural schematic diagram;

[0025] Figure 5 is Figure 1 a bending schematic diagram of the soft bionic finger Figure 1 ;

[0026] Figure 6 is Figure 1 a bending schematic diagram of the soft bionic finger Figure 2 ;

[0027] Figure 7 is Figure 1 a schematic diagram of the three soft bionic fingers in a clamping state Figure 1 ;

[0028] Figure 8 is Figure 1 a schematic diagram of the three soft bionic fingers in a clamping state Figure 2 .

[0029] The reference signs are as follows:

[0030] 10, frame; 11, first gas charging and discharging interface; 12, second gas charging and discharging interface;

[0031] 20, soft bionic finger; 21, air cavity; 22, granular gas cavity; 221, storage cavity; 222, flexible joint cavity; 223, air-permeable membrane; 23, granular material; 24, strip-shaped soft finger wall; 241, concave outer cavity wall; 242, concave joint position; 243, wire slot;

[0032] 30, rope driving mechanism; (31, 32, 33, 34), driving rope. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application.

[0034] The present application provides a rope-driven pneumatic omnidirectional variable stiffness gripper, which is implemented as shown in the accompanying drawings. Figures 1 to 8 The soft bionic finger 20 is provided with an air cavity 21 and a granular gas cavity 22; the air cavity 21 and the granular gas cavity 22 are arranged in the axial direction of the soft bionic finger 20; the granular gas cavity 22 is surrounded by the air cavity 21 on the outer side in the circumferential direction, and the granular gas cavity 22 is alternately provided with a storage cavity 221 and a flexible joint cavity 222 in the axial direction of the soft bionic finger 20, and the storage cavity 221 is filled with granular material 23; the rope driving mechanism 30 is used to adjust the swinging direction of the soft bionic finger 20; and the air pump is used to charge and discharge the air cavity 21 and the granular gas cavity 22.

[0035] In application, in order to flexibly change the bending direction of the soft bionic finger 20 in the process of driving the soft bionic finger 20 by air pressure, the strain limiting layer in the conventional pneumatic driving actuator is cancelled, and the function of the rope driving mechanism 30 is to control the length of the driving rope by tightening and loosening the driving rope, and since the driving rope is regarded as a non-stretchable inelastic rope, the length of the driving rope is fixed, and it can be regarded as a "strain limiting layer" in the conventional pneumatic driving actuator, so that when the soft bionic finger 20 is inflated and positive pressure is applied, the soft bionic finger 20 will bend to the side with shorter fixed length in the driving rope.

[0036] In addition, the pneumatic driving and the effect of particle blockage are embodied in the particle cavity 22. The positive pressure in the particle cavity 22 can make the outer membrane corresponding to the particle cavity 22 adhere to the surface of the object with a larger contact area. Then, the negative pressure can make the surface profile of the object be surrounded by the outer membrane and the particles 23 in the particle cavity 22. With the negative pressure, the stiffness of the soft bionic finger 20 is continuously increased, and a larger clamping force can be obtained. At the same time, the particle cavity 22 and the outer membrane conform to the surface of the object, which can increase the contact area and make the stress distribution more dispersed and uniform. In addition, the pneumatic driving also acts on the air cavity 21 of the soft bionic finger 20. The positive pressure in the air cavity 21, in cooperation with the driving of the rope driving mechanism 30, can make the soft bionic finger 20 fully bend and have a larger stiffness.

[0037] Further, in the process of air compression and inflation recovery of the particle cavity 22, the position of the particles 23 in the particle cavity 22 cannot be determined, and the effect of particle blockage may have a negative impact on the bending and recovery of the entire soft bionic finger 20. For example, it may cause insufficient bending, so that the entire clamping jaw cannot fully adhere to the surface of the object, or all the particles 23 are compressed into a relatively dense part during recovery, which cannot be fully recovered due to the mutual friction of the particles 23, so that the particles 23 fill the entire particle cavity 22.

[0038] In order to alleviate and eliminate these effects, the flexible joint cavity 222 of this embodiment is not filled with particles 23, but air can pass through normally, so the flexible joint cavity 222 is equivalent to the bending part of the human finger joint. Through the cavity structure, bending is achieved. In the process of deformation of the soft bionic finger 20 under the change of air pressure, the deformation of the flexible joint cavity 222 is not affected by the particle blockage, and the contraction and recovery can be more smooth.

[0039] As shown in Figure 1 , this embodiment arranges three soft bionic fingers 20 in a ring array on the rack 10 to ensure that the clamping force can be applied to the object from multiple directions when the object is clamped. Of course, the number of soft bionic fingers 20 is not limited to three. As long as the multiple soft bionic fingers 20 are arranged in a ring array on the rack 10, the number of soft bionic fingers 20 can be selected according to actual needs.

[0040] As shown in Figure 4 , this embodiment sets the particles 23 as spherical, and the shape of the particles 23 is not limited to this. According to actual application requirements, other shapes of particles 23 can also be used.

[0041] As shown in Figure 1 , Figure 2 , and Figure 4As shown, this embodiment provides that the soft bionic finger 20 includes four strip-shaped soft finger walls 24, each of which is internally provided with three storage cavities 221 and two flexible joint cavities 222, and each of which is externally provided with a concave-arc outer cavity wall 241, and the four concave-arc outer cavity walls 241 are spliced to form the air cavity 21.

[0042] After this arrangement, the soft bionic finger 20 is similar to a human finger, and has two knuckle positions, and the concave-arc outer cavity wall 241 is arranged to form the air cavity 21.

[0043] Of course, the number of the above technical features is not limited to the above arrangement, as long as the soft bionic finger 20 includes a plurality of strip-shaped soft finger walls 24, each of which is internally provided with a plurality of storage cavities 221 and a plurality of flexible joint cavities 222, and each of which is externally provided with a concave-arc outer cavity wall 241, and a plurality of concave-arc outer cavity walls 241 are spliced to form the air cavity 21.

[0044] As shown in FIG. 4, this embodiment provides that the soft bionic finger 20 is internally provided with a plurality of strip-shaped soft finger walls 24, each of which is internally provided with a plurality of storage cavities 221 and a plurality of flexible joint cavities 222, and each of which is externally provided with a concave-arc outer cavity wall 241, and a plurality of concave-arc outer cavity walls 241 are spliced to form the air cavity 21. Figures 2 to 4 As shown, this embodiment provides that the outer surface of the strip-shaped soft finger wall 24 is provided with an internally recessed joint position 242 at the position corresponding to the flexible joint cavity 222, and adjacent internally recessed joint positions 242 are annularly surrounded.

[0045] After this arrangement, the internally recessed joint position 242 is equivalent to the structure of the skin recess at the joint bending position of the human finger, that is, the soft bionic finger 20 has excellent grasping performance similar to the human finger through the bionic structure.

[0046] As shown in FIG. 5, this embodiment provides that the surface of the strip-shaped soft finger wall 24 is provided with a wire receiving groove 243 adjacent to the strip-shaped soft finger wall 24, and the wire receiving groove 243 is arranged along the axial direction of the strip-shaped soft finger wall 24; the driving rope of the rope driving mechanism 30 passes through the wire receiving groove 243 and is connected and fixed at the fingertip position of the soft bionic finger 20. Figures 1 to 3 After this arrangement, the rope driving connection between the rope driving mechanism 30 and the flexible bionic finger is realized; for example, as shown in FIG. 6, the rope driving mechanism 30 is provided with a driving rope 31, a driving rope 32, a driving rope 33, and a driving rope 34.

[0047] As shown, the length of the control driving rope 31 is the shortest, the lengths of the driving rope 32 and the driving rope 34 are consistent and slightly longer than that of the driving rope 31, and the length of the driving rope 33 is the longest, and the air cavity 21 is positively pressurized, the particle gas cavities of the driving rope 31 and the driving rope 32 and the driving rope 34 are negatively pressurized, and the other particle gas cavities are positively pressurized, so as to realize the bending posture 1 shown in the figure. Figure 5 And as shown in FIG. 7, the length of the control driving rope 31 is the longest, the lengths of the driving rope 32 and the driving rope 34 are consistent and slightly shorter than that of the driving rope 31, and the length of the driving rope 33 is the shortest, and the air cavity 21 is positively pressurized, the particle gas cavities of the driving rope 31 and the driving rope 32 and the driving rope 34 are negatively pressurized, and the other particle gas cavities are positively pressurized, so as to realize the bending posture 2 shown in the figure.

[0048] Figure 6 ​It can be seen that the lengths of the driving ropes 31 and 32 are consistent and the shortest, the lengths of the driving ropes 33 and 34 are consistent and the longest, and the particle gas cavities of the driving ropes 31 and 32 are subjected to negative pressure extraction, and all the remaining cavities are subjected to positive pressure charging, so that the bending posture 2 shown in the figure can be realized.

[0049] Since the soft bionic fingers 20 are fixed on the frame 10, the difference between the two bending postures is that the bending directions of the omnidirectional variable stiffness clamps formed by the soft bionic fingers 20 as the core are different, and since the four driving ropes can be elongated and shortened, that is, each posture can realize bending in four directions, so the bending directions of each soft bionic finger 20 are eight in total.

[0050] In addition, the positive pressure charging and negative pressure extraction of the air cavities 21 and the particle gas cavities 22 can be performed synchronously or sequentially, and the specific situation can be determined according to the appearance and size of the clamped object, as long as the particle gas cavities 22 on the bending side can continue to extract negative pressure to increase the stiffness after being attached to the object.

[0051] Since each soft bionic finger 20 has multiple bending directions and is independently controlled, the three-finger clamp formed by the soft bionic fingers 20 also has multiple clamping postures, Figure 7 and Figure 8 which shows two completely different postures of the soft bionic fingers 20 (both are viewed from the top). For objects of different shapes and sizes, the best clamping scheme can be found by mixed control of air pressure and driving rope length.

[0052] In the present application, the combination of pneumatic driving, particle blocking and rope driving can simultaneously increase the clamping force and stiffness, and compared with the way of using pneumatic driving and particle blocking to ensure clamping stiffness and using rope driving to increase clamping force, the present application has higher comprehensive clamping performance, while retaining the high compliance and variable stiffness of pneumatic driving and particle blocking. In addition, the combination of rope driving in the form of a three-finger clamp can fully utilize the control flexibility of rope driving to realize more rich clamping postures of the soft bionic fingers 20 in the clamp, and can also make the clamp not limited to clamping actions, so as to realize the operation state of two fixed fingers and one moving finger.

[0053] As shown in Figure 4 The embodiment is provided with air-permeable membranes 223 between the flexible joint cavities 222 and the adjacent storage cavities 221 on both sides, and the air-permeable membranes 223 on both sides and the outer wall of the particle gas cavities 22 form the flexible joint cavities 222, so that the air paths between the particle gas cavities 22 are connected.

[0054] As shown in Figure 4As shown in the figure, the cross section of the flexible joint cavity 222 is triangular, for example, the concave joint position 242 is arranged in the area between the two air permeable membranes 223, so that the flexible joint cavity 222 is more similar to the human finger joint structure.

[0055] As shown in the figure, Figure 1 and Figure 2 As shown in the figure, the first air charging and discharging interface 11 of the air cavity 21 and the second air charging and discharging interface 12 of the particle gas cavity 22 are arranged on the rack 10, so that the air charging and discharging treatment of the air cavity 21 and the particle gas cavity 22 is facilitated.

[0056] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements are also considered to be within the scope of the present application.

Claims

1.A rope-driven pneumatic omni-directional variable stiffness gripper, characterized in that, comprising a frame, and a plurality of soft bionic fingers, a rope-driven mechanism and a gas pump arranged on the frame; the soft bionic finger is provided with an air cavity and a granular gas cavity; the air cavity and the granular gas cavity are arranged along the axial direction of the soft bionic finger; the granular gas cavity is surrounded by the air cavity, and the granular gas cavity is alternately provided with a storage cavity and a flexible joint cavity in the axial direction of the soft bionic finger, and at least one of the storage cavities is filled with granular matter; the rope-driven mechanism is used for adjusting the swing direction of the soft bionic finger; and the gas pump is used for inflating and deflating the air cavity and the granular gas cavity. 2.The omni-directional variable stiffness gripper according to claim 1, characterized in that, a plurality of the soft bionic fingers are arranged in a ring array on the frame. 3.The omni-directional variable stiffness gripper according to claim 1, characterized in that, the granular matter is spherical. 4.The omni-directional variable stiffness gripper according to claim 1, characterized in that, the soft bionic finger comprises a plurality of strip-shaped soft finger walls, the interior of each of the strip-shaped soft finger walls is provided with a plurality of the storage cavities and a plurality of the flexible joint cavities, the outer surface of each of the strip-shaped soft finger walls is provided with a concave arc outer cavity wall, and a plurality of the concave arc outer cavity walls are spliced to form the air cavity. 5.The omni-directional variable stiffness gripper according to claim 4, characterized in that, at the position corresponding to the flexible joint cavity, the outer surface of the strip-shaped soft finger wall is provided with an inner concave joint position, and adjacent inner concave joint positions are annularly arranged. 6.The omni-directional variable stiffness gripper according to claim 4, characterized in that, the surface of adjacent strip-shaped soft finger walls is provided with a wire receiving groove, and the wire receiving groove is arranged along the axial direction of the strip-shaped soft finger wall; the driving rope of the rope-driven mechanism passes through the wire receiving groove, and the tip of the soft bionic finger is connected and fixed. 7.The omni-directional variable stiffness gripper according to claim 5, characterized in that, the flexible joint cavity is surrounded by the air-permeable membrane between the two sides of the flexible joint cavity and the adjacent storage cavities. 8.The omni-directional variable stiffness gripper according to claim 7, characterized in that, the cross section of the flexible joint cavity is triangular. 9.The omni-directional variable stiffness gripper according to claim 8, characterized in that, the inner concave joint position is arranged in the region where the two sides of the air-permeable membrane are separated from each other. 10.The omni-directional variable stiffness gripper according to claim 1, characterized in that, the first gas inflation and deflation interface of the air cavity and the second gas inflation and deflation interface of the granular gas cavity are arranged on the frame. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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